Preparation and characterization of two new forced degradation products of letrozole and development of a stability-indicating RP-LC method for its determination.

PubMed

Elkady, Ehab Farouk; Fouad, Marwa Ahmed

2015-11-01

Two new hydrolytic products of letrozole were identified and proved to be true degradation products obtained by alkaline and acidic degradation of the drug. The acid and amide forms of the nitrile groups of letrozole were prepared and identified by IR and mass spectroscopic techniques. Subsequently, a simple, precise and selective stability-indicating RPLC method was developed and validated for the determination of letrozole in the presence of its degradation products. Letrozole was subjected to alkali and acid hydrolysis, oxidation, thermal degradation and photo-degradation. The degradation products were well isolated from letrozole. The chromatographic method was achieved using gradient elution of the drug and its degradation products on a reversed phase Zorbax Eclipse C18 column (100mm x 4.6mm, 3.5 μm) using a mobile phase consisting of 0.01M KH₂PO₄and methanol at a flow rate of 1 mL min⁻¹. Quantitation was achieved with UV detection at 230 nm. Linearity, accuracy and precision were found to be acceptable over the concentration range of 0.01-80 μgmL⁻¹. The proposed method was successfully applied to the determination of letrozole in bulk, plasma and in its pharmaceutical preparation.

Degradation of Artemisinin-Based Combination Therapies Under Tropical Conditions.

PubMed

Hall, Zoe; Allan, Elizabeth Louise; van Schalkwyk, Donelly Andrew; van Wyk, Albert; Kaur, Harparkash

2016-05-04

Poor quality antimalarials, including falsified, substandard, and degraded drugs, are a serious health concern in malaria-endemic countries. Guidelines are lacking on how to distinguish between substandard and degraded drugs. "Forced degradation" in an oven was carried out on three common artemisinin-based combination therapy (ACT) brands to detect products of degradation using liquid chromatography mass spectrometry and help facilitate classification of degraded drugs. "Natural aging" of 2,880 tablets each of ACTs artemether/lumefantrine and artesunate/amodiaquine was undertaken to evaluate their long-term stability in tropical climates. Samples were aged in the presence and absence of light on-site in Ghana and in a stability chamber (London), removed at regular intervals, and analyzed to determine loss of the active pharmaceutical ingredients (APIs) over time and detect products of degradation. Loss of APIs in naturally aged tablets (both in Ghana and the pharmaceutical stability chamber) was 0-7% over 3 years (∼12 months beyond expiry) with low levels of degradation products detected. Using this developed methodology, it was found that a quarter of ACTs purchased in Enugu, Nigeria (concurrent study), that would have been classified as substandard, were in fact degraded. Presence of degradation products together with evidence of insufficient APIs can be used to classify drugs as degraded. © The American Society of Tropical Medicine and Hygiene.

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method

PubMed Central

Jahan, Md. Sarowar; Islam, Md. Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R2) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R2 > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0–103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5–20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition. PMID:25452691

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method.

PubMed

Jahan, Md Sarowar; Islam, Md Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R (2)) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R (2) > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0-103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5-20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition.

Drug stability analyzer for long duration spaceflights

NASA Astrophysics Data System (ADS)

Shende, Chetan; Smith, Wayne; Brouillette, Carl; Farquharson, Stuart

2014-06-01

Crewmembers of current and future long duration spaceflights require drugs to overcome the deleterious effects of weightlessness, sickness and injuries. Unfortunately, recent studies have shown that some of the drugs currently used may degrade more rapidly in space, losing their potency well before their expiration dates. To complicate matters, the degradation products of some drugs can be toxic. Consequently there is a need for an analyzer that can determine if a drug is safe at the time of use, as well as to monitor and understand space-induced degradation, so that drug types, formulations, and packaging can be improved. Towards this goal we have been investigating the ability of Raman spectroscopy to monitor and quantify drug degradation. Here we present preliminary data by measuring acetaminophen, and its degradation product, p-aminophenol, as pure samples, and during forced degradation reactions.

Electrochemical oxidation coupled with liquid chromatography and mass spectrometry to study the oxidative stability of active pharmaceutical ingredients in solution: A comparison of off-line and on-line approaches.

PubMed

Torres, Susana; Brown, Roland; Zelesky, Todd; Scrivens, Garry; Szucs, Roman; Hawkins, Joel M; Taylor, Mark R

2016-11-30

Stability studies of pharmaceutical drug products and pharmaceutical active substances are important to research and development in order to fully understand and maintain product quality and safety throughout its shelf-life. Oxidative forced degradation studies are among the different types of stability studies performed by the pharmaceutical industry in order to understand the intrinsic stability of drug molecules. We have been comparing the use of electrochemistry as an alternative oxidative forced degradation method to traditional forced degradation and accelerated stability studies. Using the electrochemical degradation approach the substrate oxidation takes place in a commercially available electrochemical cell and the effluent of the cell can be either a) directly infused into the mass spectrometer or b) injected in a chromatographic column for separation of the different products formed prior to the mass spectrometry analysis. To enable the study of large numbers of different experimental conditions and molecules we developed a new dual pump automated electrochemical screening platform. This system used a HPLC pump and autosampler to load and wash the electrochemical cell and deliver the oxidized sample plug to a second injection loop. This system enabled the automatic sequential analyses of large numbers of different solutions under varied experimental conditions without need for operator intervention during the run sequence. Here we describe the system and evaluate its performance using a test molecule with well characterized stability and compare results to those obtained using an off-line electrochemistry approach. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification of new impurities of enalapril maleate on oxidation in the presence of magnesium monoperoxyphthalate.

PubMed

Toporisic, Rebeka; Mlakar, Anita; Hvala, Jernej; Prislan, Iztok; Zupancic-Kralj, Lucija

2010-06-05

Stress stability testing and forced degradation were used to determine the stability of enalapril maleate (EM) and to find a degradation pathway for the drug. The degradation impurities, formed under different stressed conditions, were investigated by HPLC and UPLC-MS methods. HPLC analysis showed several degradation impurities of which several were already determined, but on oxidation in the presence of magnesium monoperoxyphthalate (MMPP) several impurities of EM were observed which were not yet characterized. The HPLC methods for determination of EM were validated. The linearity of HPLC method was established in the concentration range between 0.5 and 10 microg/mL with correlation coefficient greater than 0.99. The LOD of EM was 0.2 microg/mL and LOQ was 0.5 microg/mL. The validated HPLC method was used to determine the degradation impurities in samples after stress stability testing and forced degradation of EM. In order to identify new degradation impurities of EM after forced degradation UPLC-MS/MS(n), Orbitrap has been used. It was found that new impurities are oxidation products: (S)-1-((S)-2-((S)-1-ethoxy-4-(o,m,p-hydroxyphenyl)-1-oxobutan-2-ylamino)propanoyl)pyrrolidine-2-carboxylic acid, (2S)-1-((2S)-2-((2S)-1-ethoxy-4-hydroxy-1-oxo-4-phenylbutan-2-ylamino)propanoyl)pyrrolidine-2-carboxylic acid. (S)-2-(3-phenylpropylamino)-1-(pyrrolidin-1-yl)propan-1-one was identified as a new degradation impurity. Copyright (c) 2010. Published by Elsevier B.V.

Development and Validation of a Stability-Indicating Assay of Etofenamate by RP-HPLC and Characterization of Degradation Products

PubMed Central

Peraman, Ramalingam; Nayakanti, Devanna; Dugga, Hari Hara Theja; Kodikonda, Sudhakara

2013-01-01

A validated stability-indicating RP-HPLC method for etofenamate (ETF) was developed by separating its degradation products on a C18 (250 mm × 4.6 mm 5 μm) Qualisil BDS column using a phosphate buffer (pH-adjusted to 6.0 with orthophosphoric acid) and methanol in the ratio of 20:80 % v/v as the mobile phase at a flow rate of 1.0 mL/min. The column effluents were monitored by a photodiode array detector set at 286 nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit, and robustness. Forced degradation of etofenamate was carried out under acidic, basic, thermal, photo, and peroxide conditions and the major degradation products of acidic and basic degradation were isolated and characterized by 1H-NMR, 13C-NMR, and mass spectral studies. The mass balance of the method varied between 92–99%. PMID:24482770

Fate of products of degradation processes: consequences for climatic change.

PubMed

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

1999-03-01

The end products of atmospheric degradation are not only CO2 and H2O 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 m2 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.

In silico prediction of pharmaceutical degradation pathways: a benchmarking study.

PubMed

Kleinman, Mark H; Baertschi, Steven W; Alsante, Karen M; Reid, Darren L; Mowery, Mark D; Shimanovich, Roman; Foti, Chris; Smith, William K; Reynolds, Dan W; Nefliu, Marcela; Ott, Martin A

2014-11-03

Zeneth is a new software application capable of predicting degradation products derived from small molecule active pharmaceutical ingredients. This study was aimed at understanding the current status of Zeneth's predictive capabilities and assessing gaps in predictivity. Using data from 27 small molecule drug substances from five pharmaceutical companies, the evolution of Zeneth predictions through knowledge base development since 2009 was evaluated. The experimentally observed degradation products from forced degradation, accelerated, and long-term stability studies were compared to Zeneth predictions. Steady progress in predictive performance was observed as the knowledge bases grew and were refined. Over the course of the development covered within this evaluation, the ability of Zeneth to predict experimentally observed degradants increased from 31% to 54%. In particular, gaps in predictivity were noted in the areas of epimerizations, N-dealkylation of N-alkylheteroaromatic compounds, photochemical decarboxylations, and electrocyclic reactions. The results of this study show that knowledge base development efforts have increased the ability of Zeneth to predict relevant degradation products and aid pharmaceutical research. This study has also provided valuable information to help guide further improvements to Zeneth and its knowledge base.

Characterization of degradation products of silodosin under stress conditions by liquid chromatography/Fourier transform mass spectrometry.

PubMed

Pandeti, Sukanya; Narender, Tadigoppula; Prabhakar, Sripadi; Reddy, Thota Jagadeswar

2017-03-30

Silodosin (SDN) is a novel α 1 -adrenoceptor antagonist in the treatment of benign prostatic hyperplasia (BPH). The presence of degradation products in a drug affects not only the quality, but also the safety and efficacy of drug formulation. Thus, it is essential to develop an efficient analytical method which could be useful to selectively separate, identify and characterise of all possible degradation products of SDN which is mandatory in drug development processes. SDN was subjected to forced degradation under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions. Separation of the drug and degradation products was achieved by a liquid chromatography (LC) method using an Acquity UPLC® BEH C18 (2.1 × 100 mm, 1.7 μm; Waters) column with mobile phase consisting of 0.1% formic acid (FA) in water (A) and 0.1% FA in acetonitrile (ACN) and methanol (MeOH) (1:1) (B) as organic modifier at a flow rate of 0.15 mL min -1 in gradient elution mode. Identification and characterization of the degradation products was performed by mass spectrometry methods using an LTQ-Orbitrap mass spectrometer. A total of five degradation products (DP1 to DP5) were formed under various stress conditions and their structures were proposed with the help of tandem mass spectrometry (MS/MS) experiments and high-resolution mass spectral data. A common degradation product (DP1) was observed under acidic and basic degradation conditions. DP2 was observed under acidic, DP4 and DP5 were observed under basic hydrolytic conditions, whereas DP3 was observed under oxidative conditions. SDN was found to be labile under hydrolytic and oxidative conditions. The structures of all the degradation products were proposed. The most rational mechanisms for the formation of the degradation products under different stress conditions have been established. The proposed method can be effectively used to carry out the determination and detection of SDN and its degradation products. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Identification and Structure Elucidation of Forced Degradation Products of the Novel Propionic acid Derivative Loxoprofen: Development of Stability-Indicating Chromatographic Methods Validated as per ICH Guidelines.

PubMed

Eissa, Maya S; Abd El-Sattar, Osama I

2017-04-01

Loxoprofen sodium (LOX) is a recently developed novel propionic acid derivative. Owing to its instability under both hydrolytic and oxidative conditions, the development of simple, rapid and sensitive methods for its determination in the presence of its possible forced degradation products becomes essential. Two simple chromatographic methods, high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC), were developed associated with ultraviolet (UV) detection. In HPTLC-densitometric method, the separation of LOX from its degradation products was achieved using silica gel F254 plates and toluene:acetone:acetic acid (1.8:1.0:0.1, v/v/v) as the developing system followed by densitometric scanning at 220 nm. In the HPLC-UV method, the separation was performed using isocratic elution system with acetonitrile: 0.15% triethylamine (pH 2.2) (50:50, v/v) on C18 analytical column. The flow rate was optimized at 1.0 mL·min-1 and UV detection was achieved at 220 nm. Validation was performed in accordance with the International Conference on Harmonization guidelines and the method was perfectly applied for determination of LOX in its pharmaceutical preparation. The results obtained were statistically compared to those obtained after application of the official HPLC method, where no significant difference was found incompliance with precision and accuracy. Identification and characterization of the possible hydrolytic degradation product under alkaline conditions and that produced during oxidative degradation using hydrogen peroxide were structurally elucidated using infrared and mass spectrometry analyses. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

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.

Does partial titin degradation affect sarcomere length non-uniformities and force in active and passive myofibrils?

PubMed

Joumaa, Venus; Bertrand, Fanny; Liu, Shuyue; Poscente, Sophia; Herzog, Walter

2018-05-16

The aim of this study was to determine the role of titin in preventing the development of sarcomere length non-uniformities following activation and after active and passive stretch, by determining the effect of partial titin degradation on sarcomere length non-uniformities and force in passive and active myofibrils. Selective partial titin degradation was performed using a low dose of trypsin. Myofibrils were set at a sarcomere length of 2.4 µm and then passively stretched to sarcomere lengths of 3.4 µm and 4.4 µm. In the active condition, myofibrils were set at a sarcomere length of 2.8µm, activated and actively stretched by 1 µm/sarcomere. The extent of sarcomere length non-uniformities was calculated for each sarcomere as the absolute difference between sarcomere length and the mean sarcomere length of the myofibril. Our main finding is that partial titin degradation does not increase sarcomere length non-uniformities after passive stretch and activation compared to when titin is intact, but increases the extent of sarcomere length non-uniformities after active stretch. Furthermore, when titin was partially degraded, active and passive stresses were substantially reduced. These results suggest that titin plays a crucial role in actively stretched myofibrils and is likely involved in active and passive force production.

Stability-indicating RP-HPLC method for the simultaneous determination of escitalopram oxalate and clonazepam.

PubMed

Kakde, Rajendra B; Satone, Dinesh D; Gadapayale, Kamalesh K; Kakde, Megha G

2013-07-01

The objective of the current study was to develop a validated, specific stability-indicating reversed-phase liquid chromatographic (LC) method for the quantitative determination of escitalopram oxalate and clonazepam and their related substances in bulk drugs and pharmaceutical dosage forms in the presence of degradation products. Forced degradation studies were performed on the pure drugs of escitalopram oxalate and clonazepam, as per the stress conditions prescribed by the International Conference on Harmonization (ICH) using acid, base, oxidation, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during acid and alkaline hydrolysis and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies. Good resolution between the peaks corresponded to the active pharmaceutical ingredients, escitalopram oxalate and clonazepam, and degradation products from the analyte were achieved on an ODS Hypersil C18 column (250 × 4.6 mm) using a mobile phase consisting of a mixture of acetonitrile-50 mM phosphate buffer + 10 mM triethylamine (70:30, v/v). The detection was conducted at 268 nm. The limit of detection and the limit of quantitation for escitalopram oxalate and clonazepam were established. The stress test solutions were assayed against the qualified working standards of escitalopram oxalate and clonazepam, which indicated that the developed LC method was stability-indicating. Validation of the developed LC method was conducted as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of escitalopram oxalate and clonazepam.

Ultrasonic disintegration of biosolids for improved biodegradation.

PubMed

Nickel, Klaus; Neis, Uwe

2007-04-01

Biological cell lysis is known to be the rate-limiting step of anaerobic biosolids degradation. Shear forces generated by low frequency ultrasound can be used to disintegrate bacterial cells in sewage sludge. Thus, the quantity of dissolved organic substrate is increased. Consequently, the degradation rate and the biodegradability of organic biosolids mass are improved. Fundamental pilot-studies showed a significantly accelerated biosolids degradation with less digested sludge being produced and increased biogas production being attained. A full-scale ultrasound reactor system was developed for continuous operation under real life conditions on sewage treatment plants (STP).

Anthranilate deteriorates the structure of Pseudomonas aeruginosa biofilms and antagonizes the biofilm-enhancing indole effect.

PubMed

Kim, Soo-Kyoung; Park, Ha-Young; Lee, Joon-Hee

2015-04-01

Anthranilate and indole are alternative degradation products of tryptophan, depending on the bacterial species. While indole enhances the biofilm formation of Pseudomonas aeruginosa, we found that anthranilate, the tryptophan degradation product of P. aeruginosa, had an opposite effect on P. aeruginosa biofilm formation, in which anthranilate deteriorated the mushroom structure of biofilm. The anthranilate effect on biofilm formation was differentially exerted depending on the developmental stage and the presence of shear force. Anthranilate slightly accelerated the initial attachment of P. aeruginosa at the early stage of biofilm development and appeared to build more biofilm without shear force. But anthranilate weakened the biofilm structure in the late stage, deteriorating the mushroom structure of biofilms with shear force to make a flat biofilm. To investigate the interplay of anthranilate with indole in biofilm formation, biofilms were cotreated with anthranilate and indole, and the results showed that anthranilate antagonized the biofilm-enhancing effect of indole. Anthranilate was able to deteriorate the preformed biofilm. The effect of anthranilate and indole on biofilm formation was quorum sensing independent. AntR, a regulator of anthranilate-degrading metabolism was synergistically activated by cotreatment with anthranilate and indole, suggesting that indole might enhance biofilm formation by facilitating the degradation of anthranilate. Anthranilate slightly but significantly affected the cyclic diguaniylate (c-di-GMP) level and transcription of major extracellular polysaccharide (Psl, Pel, and alginate) operons. These results suggest that anthranilate may be a promising antibiofilm agent and antagonize the effect of indole on P. aeruginosa biofilm formation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Particulate matter formation from photochemical degradation of organophosphorus pesticides

NASA Astrophysics Data System (ADS)

Borrás, E.; Ródenas, M.; Vera, T.; Muñoz, A.

2015-12-01

Several experiments were performed in the European Photo-reactor - EUPHORE - for studying aerosol formation from organophosphorus pesticides such as diazinon, chlorpyrifos, chlorpyrifos-methyl and pirimiphos-methyl. The mass concentration yields obtained (Y) were in the range 5 - 44% for the photo-oxidation reactions in the presence and the absence of NOx. These results confirm the importance of studying pesticides as significant precursors of atmospheric particulate matter due to the serious risks associated to them. The studies based on the use of EUPHORE photoreactor provide useful data about atmospheric degradation processes of organophosphorus pesticides to the atmosphere. Knowledge of the specific degradation products, including the formation of secondary particulate matter, could complete the assessment of their potential impact, since the formation of those degradation products plays a significant role in the atmospheric chemistry, global climate change, radiative force, and are related to health effects.

Micro- and nano-scale characterization to study the thermal degradation of cement-based materials

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

Lim, Seungmin, E-mail: lim76@illinois.edu; Mondal, Paramita

2014-06-01

The degradation of hydration products of cement is known to cause changes in the micro- and nano-structure, which ultimately drive thermo-mechanical degradation of cement-based composite materials at elevated temperatures. However, a detailed characterization of these changes is still incomplete. This paper presents results of an extensive experimental study carried out to investigate micro- and nano-structural changes that occur due to exposure of cement paste to high temperatures. Following heat treatment of cement paste up to 1000 °C, damage states were studied by compressive strength test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) atomic force microscopy (AFM) and AFM image analysis.more » Using experimental results and research from existing literature, new degradation processes that drive the loss of mechanical properties of cement paste are proposed. The development of micro-cracks at the interface between unhydrated cement particles and paste matrix, a change in C–S–H nano-structure and shrinkage of C–S–H, are considered as important factors that cause the thermal degradation of cement paste. - Highlights: • The thermal degradation of hydration products of cement is characterized at micro- and nano-scale using scanning electron microscopy (SEM) and atomic force microscopy (AFM). • The interface between unhydrated cement particles and the paste matrix is considered the origin of micro-cracks. • When cement paste is exposed to temperatures above 300 ºC, the nano-structure of C-S-H becomes a more loosely packed globular structure, which could be indicative of C-S-H shrinkage.« less

Development of a validated liquid chromatographic method for quantification of sorafenib tosylate in the presence of stress-induced degradation products and in biological matrix employing analytical quality by design approach.

PubMed

Sharma, Teenu; Khurana, Rajneet Kaur; Jain, Atul; Katare, O P; Singh, Bhupinder

2018-05-01

The current research work envisages an analytical quality by design-enabled development of a simple, rapid, sensitive, specific, robust and cost-effective stability-indicating reversed-phase high-performance liquid chromatographic method for determining stress-induced forced-degradation products of sorafenib tosylate (SFN). An Ishikawa fishbone diagram was constructed to embark upon analytical target profile and critical analytical attributes, i.e. peak area, theoretical plates, retention time and peak tailing. Factor screening using Taguchi orthogonal arrays and quality risk assessment studies carried out using failure mode effect analysis aided the selection of critical method parameters, i.e. mobile phase ratio and flow rate potentially affecting the chosen critical analytical attributes. Systematic optimization using response surface methodology of the chosen critical method parameters was carried out employing a two-factor-three-level-13-run, face-centered cubic design. A method operable design region was earmarked providing optimum method performance using numerical and graphical optimization. The optimum method employed a mobile phase composition consisting of acetonitrile and water (containing orthophosphoric acid, pH 4.1) at 65:35 v/v at a flow rate of 0.8 mL/min with UV detection at 265 nm using a C 18 column. Response surface methodology validation studies confirmed good efficiency and sensitivity of the developed method for analysis of SFN in mobile phase as well as in human plasma matrix. The forced degradation studies were conducted under different recommended stress conditions as per ICH Q1A (R2). Mass spectroscopy studies showed that SFN degrades in strongly acidic, alkaline and oxidative hydrolytic conditions at elevated temperature, while the drug was per se found to be photostable. Oxidative hydrolysis using 30% H 2 O 2 showed maximum degradation with products at retention times of 3.35, 3.65, 4.20 and 5.67 min. The absence of any significant change in the retention time of SFN and degradation products, formed under different stress conditions, ratified selectivity and specificity of the systematically developed method. Copyright © 2017 John Wiley & Sons, Ltd.

The application of electrochemistry to pharmaceutical stability testing--comparison with in silico prediction and chemical forced degradation approaches.

PubMed

Torres, Susana; Brown, Roland; Szucs, Roman; Hawkins, Joel M; Zelesky, Todd; Scrivens, Garry; Pettman, Alan; Taylor, Mark R

2015-11-10

The aim of this study was to evaluate the use of electrochemistry to generate oxidative degradation products of a model pharmaceutical compound. The compound was oxidized at different potentials using an electrochemical flow-cell fitted with a glassy carbon working electrode, a Pd/H2 reference electrode and a titanium auxiliary electrode. The oxidative products formed were identified and structurally characterized by LC-ESI-MS/MS using a high resolution Q-TOF mass spectrometer. Results from electrochemical oxidation using electrolytes of different pH were compared to those from chemical oxidation and from accelerated stability studies. Additionally, oxidative degradation products predicted using an in silico commercially available software were compared to those obtained from the various experimental methods. The electrochemical approach proved to be useful as an oxidative stress test as all of the final oxidation products observed under accelerated stability studies could be generated; previously reported reactive intermediate species were not observed most likely because the electrochemical mechanism differs from the oxidative pathway followed under accelerated stability conditions. In comparison to chemical degradation tests electrochemical degradation has the advantage of being much faster and does not require the use of strong oxidizing agents. Moreover, it enables the study of different operating parameters in short periods of time and optimisation of the reaction conditions (pH and applied potential) to achieve different oxidative products mixtures. This technique may prove useful as a stress test condition for the generation of oxidative degradation products and may help accelerate structure elucidation and development of stability indicating analytical methods. Copyright © 2015 Elsevier B.V. All rights reserved.

A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms.

PubMed

Rao, Dantu Durga; Satyanarayana, N V; Malleswara Reddy, A; Sait, Shakil S; Chakole, Dinesh; Mukkanti, K

2010-02-05

A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280nm. The run time was 8min within which desloratadine and its five impurities were well separated. Desloratadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Desloratadine was found to degrade significantly in oxidative and thermal stress conditions and stable in acid, base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of desloratadine in pharmaceutical dosage forms.

Kinetics of degradation of enalapril maleate in dosage forms.

PubMed

Stanisz, Beata

2004-01-01

The effect of humidity and temperature on the stability of enalapril maleate (ENA) in tablets have been studied. Tablets with ENA were stored in final packs (blisters) and without final packs in the atmosphere of increased humidity (76.4 % RH) and in the temperature range from 313 K to 333 K (forced degradation test). Degradation of ENA in tablets stored in final packs and without final packs followed the first order reaction model. During this study, the product of hydrolysis of the ester group and intramolecular cyclization have been observed. Thermodynamic parameters (activation energies, enthalpy and entropy) for the decomposition of ENA in tablets were calculated.

Forced Degradation Studies of Aloe Emodin and Emodin by HPTLC.

PubMed

Narayanan, Sindhu; Jadhav, Aruna P; Kadam, V J

2015-01-01

Anthraquinones are natural phenolic compounds, which are reported to act as anti-aging, anti-inflammatory, antioxidant, anti-cancer, laxative and antitumor agents. They are abudant in plants like candle bush, aloes, cascara bark and rhubarb. The present work was to observe the effect of different forced degradation conditions by high-performance thin layer chromatography on potential markers i.e. aloe emodin and emodin. Both aloe emodin and emodin were subjected to various forced degradation studies such as oxidation, acid and alkaline hydrolysis, photolysis, hydrolytic and thermal degradation. Aloe emodin, was more susceptible to acid hydrolysis and degradation was found to a lesser extent under thermal degradation whereas significant degradation was observed under acid hydrolysis, lesser extent was observed under alkali hydrolysis for emodin. Forced degradation studies on aloe emodin and emodin gives information about its storage and intrinsic stability conditions considering the advanced pharmaceutical aspects of formulation.

Evaluation of Force Degradation Pattern of Elastomeric Ligatures and Elastomeric Separators in Active Tieback State.

PubMed

Mohammadi, Amir; Mahmoodi, Farhang

2015-01-01

Background and aims. The purpose of this study was to evaluate initial force and force decay of commercially available elastomeric ligatures and elastomeric separators in active tieback state in a simulated oral environment. Materials and methods. A total of 288 elastomeric ligatures and elastomeric separators from three manufacturers (Dentaurum, RMO, 3M Unitek) were stretched to 100% and 150% of their original inner diameter. Force levels were measured initially and at 3-minute, 24-hour, and 1-, 2-, 3- and 4-week intervals. Data were analyzed by univariate analysis of variance and a post hoc Tukey test. Results. The means of initial forces of elastomeric ligatures and separators from three above-mentioned companies, when stretched to 100% of their inner diameters, were 199, 305 and 284 g, and 330, 416, 330 g; when they were stretched to 150% of their inner diameters the values were 286, 422 and 375 g, and 433, 540 and 504 g, respectively. In active tieback state, 11-18% of the initial force of the specimens was lost within the first 3 minutes and 29-63% of the force decay occurred in the first 24 hours; then force decay rate decreased. 62-81% of the initial force was lost in 4 weeks. Although force decay pattern was identical in all the products, the initial force and force decay of Dentaurum elastomeric products were less than the similar products of other companies (P<0.05). Under the same conditions, the force of elastomeric separators was greater than elastomeric ligatures of the same company. Conclusion. Regarding the force pattern of elastomeric ligatures and separators and optimal force for tooth movement, many of these products can be selected for applying orthodontic forces in active tieback state.

A validated specific stability-indicating RP-HPLC assay method for Ambrisentan and its related substances.

PubMed

Narayana, M B V; Chandrasekhar, K B; Rao, B M

2014-09-01

A validated specific stability-indicating reverse-phase liquid chromatographic method was developed for the quantitative determination of Ambrisentan as well as its related substances in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its related impurities. Forced degradation studies were performed on bulk samples of Ambrisentan as per the ICH-prescribed stress conditions using acid, base, oxidative, thermal stress and photolytic degradation to show the stability-indicating power of the LC method. Significant degradation in acidic, basic stress conditions was observed and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from the forced degradation studies and the impurity-spiked solution. Good resolution between the peaks corresponds to Ambrisentan-related impurities and degradation products from the analyte were achieved on a SunFire C18 column using a mobile phase consisting of a mixture of potassium dihydrogen orthophosphate at a pH adjusted to 2.5 with ortho-phosphoric acid in water and a mixture of acetonitrile:methanol using a simple linear gradient. The detection was carried out at 225 nm. The limit of detection and the limit of quantification for the Ambrisentan and its related impurities were established. The stressed test solutions were assayed against the qualified working standard of Ambrisentan and the mass balance in each case was between 98.9 and 100.3%, indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per the ICH requirements. The developed method was found to be suitable to check the quality of bulk samples of Ambrisentan at the time of batch release and also during its storage (long-term and accelerated stability). © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Modeling Degradation Product Partitioning in Chlorinated-DNAPL Source Zones

NASA Astrophysics Data System (ADS)

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-saturation ganglia, while diffusion within the DNAPL should be considered for larger NAPL pools. These results offer important insights to the monitoring and interpretation of bioremediation strategies employed within DNAPL source zones.

Gradient RP-HPLC method for the determination of potential impurities in atazanavir sulfate.

PubMed

Chitturi, Sreenivasa Rao; Somannavar, Yallappa Somappa; Peruri, Badarinadh Gupta; Nallapati, Sreenivas; Sharma, Hemant Kumar; Budidet, Shankar Reddy; Handa, Vijay Kumar; Vurimindi, Hima Bindu

2011-04-28

This paper proposes a simple and selective RP-HPLC method for the determination of process impurities and degradation products (degradants) of atazanavir sulfate (ATV) drug substance. Chromatographic separation was achieved on Ascentis(®) Express C8, (150mm×4.6mm, 2.7μm) column thermostated at 30°C under gradient elution by a binary mixture of potassium dihydrogen phosphate (pH 3.5, 0.02M) and ACN at a flow rate of 1.0ml/min. A photodiode array (PDA) detector set at 250nm was used for detection. Stress testing (forced degradation) of ATV was carried out under acidic, alkaline, oxidative, photolytic, thermal and humidity conditions. In presence of alkali, ATV transformed into cyclized products and the order of degradation reaction is determined by the method of initial rates. The unknown process impurities and alkaline degradants are isolated by preparative LC and characterized by ESI-MS/MS, (1)H NMR, and FT-IR spectral data. The developed method is validated with respect to sensitivity (lod and loq), linearity, precision, accuracy and robustness and can be implemented for routine quality control analysis and stability testing of ATV. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and validation of a stability-indicating RP-HPLC method for determination of atomoxetine hydrochloride in tablets.

PubMed

Patel, Sejal K; Patel, Natvarlal J

2010-01-01

This paper describes the development of a stability-indicating RP-HPLC method for the determination of atomoxetine hydrochloride (ATX) in the presence of its degradation products generated from forced decomposition studies. The drug substance was subjected to stress conditions of acid, base, oxidation, wet heat, dry heat, and photodegradation. In stability tests, the drug was susceptible to acid, base, oxidation, and dry and wet heat degradation. It was found to be stable under the photolytic conditions tested. The drug was successfully separated from the degradation products formed under stress conditions on a Phenomenex C18 column (250 x 4.6 mm id, 5 microm particle size) by using acetonitrile-methanol-0.032 M ammonium acetate (55 + 05 + 40, v/v/v) as the mobile phase at 1.0 mL/min and 40 degrees C. Photodiode array detection at 275 nm was used for quantitation after RP-HPLC over the concentration range of 0.5-5 microg/mL with a mean recovery of 100.8 +/- 0.4% for ATX. Statistical analysis demonstrated that the method is repeatable, specific, and accurate for the estimation of ATX. Because the method effectively separates the drug from its degradation products, it can be used as a stability-indicating method.

Development and Validation of an RP-HPLC Method for the Determination of Vinpocetine and Folic Acid in the Presence of a Vinpocetine Alkaline Degradation Product in Bulk and in Capsule Form.

PubMed

Elkady, Ehab F; Tammam, Marwa H; Mohamed, Ayman A

2017-05-01

An alkaline-forced degradation hydrolytic product of vinpocetine was prepared and characterized by 1H-NMR, FTIR spectroscopy, and MS. Subsequently, a simple, selective, and validated reversed-phase HPLC method was developed for the simultaneous estimation of vinpocetine and folic acid in the presence of a vinpocetine alkaline degradation product. Chromatographic separation was achieved using an isocratic mobile phase consisting of acetonitrile-0.02 M KH2PO4 [containing 0.2% (v/v) triethylamine and adjusted to pH 6 with orthophosphoric acid; (80 + 20, v/v)] at a flow rate of 0.9 mL/min at ambient temperature on a Eurospher II C18 (250 × 4.6 mm, 5 μm) column, with UV detection at 280 nm for folic acid and 230 nm for vinpocetine and its alkaline hydrolytic product. Linearity, accuracy, and precision were found to be acceptable over a concentration range of 12.5-200 μg/mL for vinpocetine and 1-16 μg/mL for folic acid. The proposed method was successfully applied for the determination of both drugs and a vinpocetine hydrolysis product in a laboratory-prepared mixture and in a capsule containing both drugs.

Development of Impurity Profiling Methods Using Modern Analytical Techniques.

PubMed

Ramachandra, Bondigalla

2017-01-02

This review gives a brief introduction about the process- and product-related impurities and emphasizes on the development of novel analytical methods for their determination. It describes the application of modern analytical techniques, particularly the ultra-performance liquid chromatography (UPLC), liquid chromatography-mass spectrometry (LC-MS), high-resolution mass spectrometry (HRMS), gas chromatography-mass spectrometry (GC-MS) and high-performance thin layer chromatography (HPTLC). In addition to that, the application of nuclear magnetic resonance (NMR) spectroscopy was also discussed for the characterization of impurities and degradation products. The significance of the quality, efficacy and safety of drug substances/products, including the source of impurities, kinds of impurities, adverse effects by the presence of impurities, quality control of impurities, necessity for the development of impurity profiling methods, identification of impurities and regulatory aspects has been discussed. Other important aspects that have been discussed are forced degradation studies and the development of stability indicating assay methods.

High-performance liquid chromatographic analysis of dextromethorphan, guaifenesin and benzoate in a cough syrup for stability testing.

PubMed

Galli, V; Barbas, C

2004-09-10

A method has been developed for the analysis of a cough syrup containing dextromethorphan, guaifenesin, benzoic acid, saccharin and other components. Forced degradation was also studied to demonstrate that the method could be employed during a stability study of the syrup. Final conditions were phosphate buffer (25 mM, pH 2.8) with triethylamine (TEA)-acetonitrile (75:25, v/v). In such conditions, all the actives, excipients and degradation products were baseline resolved in less than 14 min, and different wavelengths were used for the different analytes and related compounds.

Homeostatic maintenance via degradation and repair of elastic fibers under tension

NASA Astrophysics Data System (ADS)

Alves, Calebe; Araújo, Ascanio D.; Oliveira, Cláudio L. N.; Imsirovic, Jasmin; Bartolák-Suki, Erzsébet; Andrade, José S.; Suki, Béla

2016-06-01

Cellular maintenance of the extracellular matrix requires an effective regulation that balances enzymatic degradation with the repair of collagen fibrils and fibers. Here, we investigate the long-term maintenance of elastic fibers under tension combined with diffusion of general degradative and regenerative particles associated with digestion and repair processes. Computational results show that homeostatic fiber stiffness can be achieved by assuming that cells periodically probe fiber stiffness to adjust the production and release of degradative and regenerative particles. However, this mechanism is unable to maintain a homogeneous fiber. To account for axial homogeneity, we introduce a robust control mechanism that is locally governed by how the binding affinity of particles is modulated by mechanical forces applied to the ends of the fiber. This model predicts diameter variations along the fiber that are in agreement with the axial distribution of collagen fibril diameters obtained from scanning electron microscopic images of normal rat thoracic aorta. The model predictions match the experiments only when the applied force on the fiber is in the range where the variance of local stiffness along the fiber takes a minimum value. Our model thus predicts that the biophysical properties of the fibers play an important role in the long-term regulatory maintenance of these fibers.

New approach for determination of the degradation products of fenspiride hydrochloride found in oral liquid formulations.

PubMed

Cioroiu, Bogdan I; Caba, Ioana C; Prisăcaru, Irina; Cioroiu, Mona E; Lazar, Mihai I; Niculaua, Marius

2018-05-01

Fenspiride hydrochloride (FNS) is used in treating chronic inflammatory diseases, most commonly as a liquid oral solution. FNS produces degradation products along with fenspiride N-oxide (FNO) and 1-phenylethyl-4-hydroxy-4-aminomethyl piperidine hydrochloride (PHAP). We aimed to develop and validate a chromatographic method in order to identify the main degradation products in the presence of other compounds from a liquid preparation. The method used a dual gradient using two buffer solutions: the first with pH 4.5 (buffer 1, pH 4.5-MeOH 90:10%, v/v) and the second with pH 2.9 (buffer 2, pH 2.9-acetronitrile-methanol, 65:15:10%, v/v/v). As mentioned, there was a modification of the organic mixture, starting with 10% methanol and ending with a mixture of acetonitrile-methanol (15:10%, v/v). The flow-rate was 1.5 mL/min. According to the elution program, experimental conditions started with 100% solution S1, which decreased to 0% and, simultaneously, solution S2 increased to 100% during the first 10 min and was maintained for a further 5 min. After 15 min, initial conditions were re-established. The linearity interval was 0.5-2 μg/mL and the minimum correlation coefficient was 0.999. The recovery factor was 100.47-103.17% and the limit of quantification was 0.19-0.332 μg/mL. Intra-day maximum precision was 4.08% for FNS and 2.65% for PHAP. This double-gradient mobile phase produced good specificity in relation to the degradation products of FNS and other constituents of the oral liquid formulation. Forced degradation studies revealed other related substances that were confirmed in mass balance analyses. Degradation products were confirmed in acidic, basic and oxidative media. Copyright © 2017 John Wiley & Sons, Ltd.

Influence of different beverages on the force degradation of intermaxillary elastics: an in vitro study.

PubMed

Leão Filho, Jorge César Borges; Gallo, Daphine Beatriz; Santana, Regis Meller; Guariza-Filho, Odilon; Camargo, Elisa Souza; Tanaka, Orlando Motohiro

2013-01-01

The aim of this study was to evaluate in vitro the effects of frequently ingested beverages on force degradation of intermaxillary elastics. One hundred and eighty 1/4-inch intermaxillary elastics (TP Orthodontics) were immersed into six different beverages: (1) Coca-Cola®; (2) Beer; (3) Orange juice; (4) Red wine; (5) Coffee and (6) artificial saliva (control). The period of immersion was 15 min for the first and second cycles and 30 min for the third to fifth cycles. Tensile forces were read in a tensile testing machine before and after the five immersion cycles. One-way repeated measures ANOVA was used to identify significant differences. Force degradation was seen in all evaluated groups and at all observation periods (p<0.05). A greater degree of degradation was present at the initial periods, decreasing gradually over time. However, no statistically significant differences were seen among groups at the same periods, showing that different groups behaved similarly. The chemical nature of the evaluated beverages was not able to influence the degree of force degradation at all observation periods.

Accurate prediction of vaccine stability under real storage conditions and during temperature excursions.

PubMed

Clénet, Didier

2018-04-01

Due to their thermosensitivity, most vaccines must be kept refrigerated from production to use. To successfully carry out global immunization programs, ensuring the stability of vaccines is crucial. In this context, two important issues are critical, namely: (i) predicting vaccine stability and (ii) preventing product damage due to excessive temperature excursions outside of the recommended storage conditions (cold chain break). We applied a combination of advanced kinetics and statistical analyses on vaccine forced degradation data to accurately describe the loss of antigenicity for a multivalent freeze-dried inactivated virus vaccine containing three variants. The screening of large amounts of kinetic models combined with a statistical model selection approach resulted in the identification of two-step kinetic models. Predictions based on kinetic analysis and experimental stability data were in agreement, with approximately five percentage points difference from real values for long-term stability storage conditions, after excursions of temperature and during experimental shipments of freeze-dried products. Results showed that modeling a few months of forced degradation can be used to predict various time and temperature profiles endured by vaccines, i.e. long-term stability, short time excursions outside the labeled storage conditions or shipments at ambient temperature, with high accuracy. Pharmaceutical applications of the presented kinetics-based approach are discussed. Copyright © 2018 The Author. Published by Elsevier B.V. All rights reserved.

Bacterial Degradation of DNT and TNT Mixtures

DTIC Science & Technology

2005-10-31

deletion derivatives and subclones that allowed isolated synthesis of the other gene products shown in Figure II- 1 , did not provide activity to transform...Research Laboratories, Tyndall AFB, Florida) Glenn R. Johnson Air Force Research Laboratories, Tyndall AFB, Florida October 31, 2005 Version 1 ...burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing

Utility of surface enhanced Raman spectroscopy (SERS) for elucidation and simultaneous determination of some penicillins and penicilloic acid using hydroxylamine silver nanoparticles.

PubMed

El-Zahry, Marwa R; Refaat, Ibrahim H; Mohamed, Horria A; Rosenberg, Erwin; Lendl, Bernhard

2015-11-01

Elucidation and quantitative determination of some of commonly used penicillins (ampicillin, penicillin G and carbenicillin) in the presence of their main degradation product (penicilloic acid) were developed. Forced acidic and basic degradation processes were applied at different time intervals. The formed degradation products were elucidated and quantified using surface enhanced Raman spectroscopy (SERS). Silver nanoparticles (AgNPs) prepared by reduction of silver nitrate using hydroxylamine-HCl in alkaline medium were used as SERS substrate. The results obtained in SERS were confirmed by the application of LC/MS method. The concentration range was 100-600 ng/ml in case of the studied penicillins and 100-700 ng/ml in case of penicilloic acid. An excellent correlation coefficient was found in case of ampicillin (r=0.9993) and in the case of penicilloic acid (r=0.9997). Validation procedures were carried out including precision, robustness and accuracy by comparing F- and t-values of both the proposed and reported methods. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of different beverages on the force degradation of intermaxillary elastics: an in vitro study

PubMed Central

LEÃO FILHO, Jorge César Borges; GALLO, Daphine Beatriz; SANTANA, Regis Meller; GUARIZA-FILHO, Odilon; CAMARGO, Elisa Souza; TANAKA, Orlando Motohiro

2013-01-01

Objective: The aim of this study was to evaluate in vitro the effects of frequently ingested beverages on force degradation of intermaxillary elastics. Material and Methods: One hundred and eighty 1/4-inch intermaxillary elastics (TP Orthodontics) were immersed into six different beverages: (1) Coca-Cola®; (2) Beer; (3) Orange juice; (4) Red wine; (5) Coffee and (6) artificial saliva (control). The period of immersion was 15 min for the first and second cycles and 30 min for the third to fifth cycles. Tensile forces were read in a tensile testing machine before and after the five immersion cycles. One-way repeated measures ANOVA was used to identify significant differences. Results: Force degradation was seen in all evaluated groups and at all observation periods (p<0.05). A greater degree of degradation was present at the initial periods, decreasing gradually over time. However, no statistically significant differences were seen among groups at the same periods, showing that different groups behaved similarly. Conclusion: The chemical nature of the evaluated beverages was not able to influence the degree of force degradation at all observation periods. PMID:23739862

General Urban Warfare Amphibious Logistics Applications. Volume 2. Operations Plan.

DTIC Science & Technology

1983-06-23

measures to degrade or eliminate enemy hostile intelligence or counterintelligence capabilities affecting the efficient conduct of amphibious...networks, and harbor port facilities. If controlled and exploited by enemy agencies, landing force progress and capabilities could be degraded . ECM...control for follow-on forces, and supplementing ATF communications where degraded by buildings within the metropolitan boundary. d. Transgortation S.(1

Evaluation of force degradation characteristics of orthodontic latex elastics in vitro and in vivo.

PubMed

Wang, Tong; Zhou, Gang; Tan, Xianfeng; Dong, Yaojun

2007-07-01

To evaluate the characteristics of force degradation of latex elastics in clinical applications and in vitro studies. Samples of 3/16-inch latex elastics were investigated, and 12 students between the ages of 12 and 15 years were selected for the intermaxillary and intramaxillary tractions. The elastics in the control groups were set in artificial saliva and dry room conditions and were stretched 20 mm. The repeated-measure two-way analysis of variance and nonlinear regression analysis were used to identify statistical significance. Overall, there were statistically significant differences between the different methods and observation intervals. At 24- and 48-hour time intervals, the force decreased during in vivo testing and in artificial saliva (P < .001), whereas there were no significant differences in dry room conditions (P > .05). In intermaxillary traction the percentage of initial force remaining after 48 hours was 61%. In intramaxillary traction and in artificial saliva the percentage of initial force remaining was 71%, and in room conditions 86% of initial force remained. Force degradation of latex elastics was different according to their environmental conditions. There was significantly more force degradation in intermaxillary traction than in intramaxillary traction. The dry room condition caused the least force loss. There were some differences among groups in the different times to start wearing elastics in intermaxillary traction but no significant differences in intramaxillary traction.

Shielded transient self-interaction of a bunch entering a circle from a straight path

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

Li, R.; Bohn, C.L.; Bisognano, J.J.

1997-08-01

Recent developments in electron-gun and injector technologies enable production of short (mm-length), high-charge (nC-regime) bunches. In this parameter regime, the curvature effect on the bunch self-interaction, by way of coherent synchrotron radiation (CSR) and space-charge forces as the beam traverses magnet bends, may cause serious emittance degradation. In this paper, the authors study an electron bunch orbiting between two infinite, parallel conducting plates. The bunch moves on a trajectory from a straight path to a circular orbit and begins radiating. Transient effects, arising from CSR and space-charge forces generated from source particles both on the bend and on the straightmore » path prior to the bend, are analyzed using Lienard-Wiechert fields, and their overall net effect is obtained. The influence of the plates on the transients is contrasted to their shielding of the steady-state radiated power. Results for emittance degradation induced by this self-interaction are also presented.« less

Development and Validation of a Stability-Indicating RP-HPLC Method for Duloxetine Hydrochloride in its Bulk and Tablet Dosage Form

PubMed Central

Chhalotiya, Usmangani K.; Bhatt, Kashyap K.; Shah, Dimal A.; Baldania, Sunil L.

2010-01-01

The objective of the present work was to develop a stability-indicating RP-HPLC method for duloxetine hydrochloride (DUL) in the presence of its degradation products generated from forced decomposition studies. The drug substance was found to be susceptible to stress conditions of acid hydrolysis. The drug was found to be stable to dry heat, photodegradation, oxidation and basic condition attempted. Successful separation of the drug from the degradation products formed under acidic stress conditions was achieved on a Hypersil C-18 column (250 mm × 4.6 mm id, 5μm particle size) using acetonitrile: 0.01 M potassium dihydrogen phosphate buffer (pH 5.4 adjusted with orthophosphoric acid) (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. Quantification was achieved with photodiode array detection at 229 nm over the concentration range 1–25 μg/ml with range of recovery 99.8–101.3 % for DUL by the RP-HPLC method. Statistical analysis proved the method to be repeatable, specific, and accurate for estimation of DUL. It can be used as a stability-indicating method due to its effective separation of the drug from its degradation products, PMID:21179321

Land Degradation Processes in the Humid Ethiopian highlands

NASA Astrophysics Data System (ADS)

Steenhuis, Tammo; Tebebu, Tigist; Belachew, Meseret; Langendoen, Eddy; Giri, Shree; Tilahun, Seifu

2017-04-01

Land degradation after forest clearing forces a distinct pattern on agricultural production starting with high yields just after clearing to poor productivity or even abandonment after 30-40 years. In the humid Ethiopian highlands forest soils have initial a high organic matter content that decreases with time after clearing. When the organic matter becomes less than 3%, aggregates break up, other cementing elements are being leached out and the texture becomes finer. Since settling velocity in water is related to particle size, the finer soil increases sediment concentration in the infiltration water and hardpan formation accelerates restricting deep percolation of water. This in turn affect the hydrology in which an excess water flows more rapidly as lateral flow to valley bottoms which become wetter with gully formation starting to transmit the additional water down slope approximately 10 years after the initial clearing. This degradation pattern occurs in all soils in the Ethiopian highlands, but the severity varies with climate and parent material. Although we do not yet understand to what degree these factors influence the degradation pattern, it is important to recognize the process because it directly affects the effectiveness of imposed management practices. In this presentation, we will highlight the degradation process for two watersheds in the semi humid Ethiopian highlands. We will document how soil properties changes and discuss hardpan formation and gully development. In addition, we will consider the effect of presently implemented governmental sponsored conservation practices and alternative management practices that might be more beneficial. We are looking forward to discussions on combating the effect of soil degradation in tropical monsoonal regions.

Stable Carbon Isotope Evidence and Quantification of Reductive Dechlorination of Chlorinated Ethenes at Kelly AFB, TX

NASA Astrophysics Data System (ADS)

Morrill, P.; Lacrampe-Couloume, G.; Slater, G.; Sleep, B.; Edwards, E.; McMaster, M.; Major, D.; Sherwood Lollar, B.

2002-12-01

Cis-1, 2-dichloroethene (cDCE) was the primary volatile organic compound (VOC) after biostimulation of a perchloroethene (PCE) plume in a pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. A stable natural microbial consortium, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene was added in a pilot test area (PTA). After the addition of KB-1 stable carbon isotope values were measured for each chlorinated ethene to verify the occurrence of reductive dechlorination and quantify the extent of cDCE degradation. After bioaugmentation with KB-1, PCE, TCE and cDCE concentrations declined, while VC concentrations increased and subsequently decreased, as ethene became the dominant transformation product measured. Shifts in carbon isotopic values up to 2.7 permil, 6.4 permil, 10.9 permil and 10.6 permil were observed for PCE, TCE, cDCE and VC respectively. These isotopic shifts are consistent with the effects of biodegradation observed during laboratory and field studies. Most notably, isotopic enrichment trends characteristic of reductive dechlorination were detectable in the parent compounds before measurable concentrations of daughter products VC and ethene were produced. These results illustrate the advantage of using the more sensitive compound specific isotope analysis to confirm degradation in addition to the traditional method of monitoring the appearance of degradation products. Fractionation factors obtained from laboratory studies were used in conjunction with isotope data measured in the field to estimate the extent of cDCE degraded. It is estimated that within a 44 day period, 37 to 48 percent of the cDCE was reductively dechlorinated. Independent biodegradation estimates using data from a bromide tracer test, a groundwater flow model, and concentration analyses were all in good agreement with the isotope degradation estimate.

Long-term stability of acyclovir in 0.9% NaCl infusion polyolefin bags at 5±3°C after freeze-thaw treatment: a generic product versus the brand name.

PubMed

Dewulf, J; Galanti, L; Godet, M; Gillet, P; Jamart, J; Hecq, J-D

2015-03-01

The aim of the study was to investigate the long-term stability of acyclovir 5 mg/mL (a generic product versus the brand name) in NaCl 0.9% after storage at 5±3°C and to evaluate the influence of initial freezing and microwave thawing on this stability. Five bags of Acyclovir® Hospira 5 mg/mL (A) and five bags of Zovirax® GSK 5 mg/mL (B) were prepared under aseptic conditions and stored 3 months at -20°C, then thawed and stored 30 days at 4°C. Five bags of Acyclovir® 5 mg/mL (C) and five bags of Zovirax® 5 mg/mL (D) were also prepared under aseptic conditions and stored 30 days at 5±3°C. Optic density measurement at different wavelengths, pH measurement and optic microscope observations were performed periodically during the storage. A forced degradation test with HCl 12 M and NaOH 5 M before and after heating at 100°C was also performed. The concentrations were measured by HPLC-PDA. The only one forced degradation test that yielded chromatograms with degradation products peak was the test with the acid solution heated at 100°C without interference with the native product. No significant change in pH values or optic densities were seen during the study for both products. No crystals were seen with the optic microscope during the study. Acyclovir® and Zovirax® solutions were stable for at least 21 days according to the FDA recommendations. Moreover, there was no statistical difference between regression lines of those two products and two storage conditions. Under the conditions of this study, Acyclovir® 5 mg/mL in 100 mL of NaCl 0.9% infusion remains stable at least for 21 days at 5±3°C with or without freezing at -20°C during the three previous months. There is no statistical difference between the brand name and a generic product. Acyclovir may be prepared in advanced by a centralized intravenous additive service, frozen in polyolefin bags and microwave thawed before storage under refrigeration until 21 days. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Bioremediation of contaminated groundwater

DOEpatents

Hazen, Terry C.; Fliermans, Carl B.

1995-01-01

An apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants; an oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth; withholding it periodicially forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene.

Bioremediation of contaminated groundwater

DOEpatents

Hazen, T.C.; Fliermans, C.B.

1995-01-24

An apparatus and method are described for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants. An oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth. Withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene. 3 figures.

Biofilm and Diatom Succession on Polyethylene (PE) and Biodegradable Plastic Bags in Two Marine Habitats: Early Signs of Degradation in the Pelagic and Benthic Zone?

PubMed Central

Laforsch, Christian; Weber, Miriam

2015-01-01

The production of biodegradable plastic is increasing. Given the augmented littering of these products an increasing input into the sea is expected. Previous laboratory experiments have shown that degradation of plastic starts within days to weeks. Little is known about the early composition and activity of biofilms found on biodegradable and conventional plastic debris and its correlation to degradation in the marine environment. In this study we investigated the early formation of biofilms on plastic shopper bags and its consequences for the degradation of plastic. Samples of polyethylene and biodegradable plastic were tested in the Mediterranean Sea for 15 and 33 days. The samples were distributed equally to a shallow benthic (sedimentary seafloor at 6 m water depth) and a pelagic habitat (3 m water depth) to compare the impact of these different environments on fouling and degradation. The amount of biofilm increased on both plastic types and in both habitats. The diatom abundance and diversity differed significantly between the habitats and the plastic types. Diatoms were more abundant on samples from the pelagic zone. We anticipate that specific surface properties of the polymer types induced different biofilm communities on both plastic types. Additionally, different environmental conditions between the benthic and pelagic experimental site such as light intensity and shear forces may have influenced unequal colonisation between these habitats. The oxygen production rate was negative for all samples, indicating that the initial biofilm on marine plastic litter consumes oxygen, regardless of the plastic type or if exposed in the pelagic or the benthic zone. Mechanical tests did not reveal degradation within one month of exposure. However, scanning electron microscopy (SEM) analysis displayed potential signs of degradation on the plastic surface, which differed between both plastic types. This study indicates that the early biofilm formation and composition are affected by the plastic type and habitat. Further, it reveals that already within two weeks biodegradable plastic shows signs of degradation in the benthic and pelagic habitat. PMID:26394047

Biofilm and Diatom Succession on Polyethylene (PE) and Biodegradable Plastic Bags in Two Marine Habitats: Early Signs of Degradation in the Pelagic and Benthic Zone?

PubMed

Eich, Andreas; Mildenberger, Tobias; Laforsch, Christian; Weber, Miriam

2015-01-01

The production of biodegradable plastic is increasing. Given the augmented littering of these products an increasing input into the sea is expected. Previous laboratory experiments have shown that degradation of plastic starts within days to weeks. Little is known about the early composition and activity of biofilms found on biodegradable and conventional plastic debris and its correlation to degradation in the marine environment. In this study we investigated the early formation of biofilms on plastic shopper bags and its consequences for the degradation of plastic. Samples of polyethylene and biodegradable plastic were tested in the Mediterranean Sea for 15 and 33 days. The samples were distributed equally to a shallow benthic (sedimentary seafloor at 6 m water depth) and a pelagic habitat (3 m water depth) to compare the impact of these different environments on fouling and degradation. The amount of biofilm increased on both plastic types and in both habitats. The diatom abundance and diversity differed significantly between the habitats and the plastic types. Diatoms were more abundant on samples from the pelagic zone. We anticipate that specific surface properties of the polymer types induced different biofilm communities on both plastic types. Additionally, different environmental conditions between the benthic and pelagic experimental site such as light intensity and shear forces may have influenced unequal colonisation between these habitats. The oxygen production rate was negative for all samples, indicating that the initial biofilm on marine plastic litter consumes oxygen, regardless of the plastic type or if exposed in the pelagic or the benthic zone. Mechanical tests did not reveal degradation within one month of exposure. However, scanning electron microscopy (SEM) analysis displayed potential signs of degradation on the plastic surface, which differed between both plastic types. This study indicates that the early biofilm formation and composition are affected by the plastic type and habitat. Further, it reveals that already within two weeks biodegradable plastic shows signs of degradation in the benthic and pelagic habitat.

Understanding the causes of changing grassland use and productivity in Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Zhang, Y.; Gao, L.; Qiao, G.; Chen, J.

2012-12-01

Some dramatic changes of grassland use and productivity have been taking place in Inner Mongolia in the past half century. While the changes are apparently driven by both socio-economic factors and climate, their contribution and interaction are largely unknown. We hypothesize that population growth is an important driving force behind the loss and degradation of the grassland, the market forces and institutional factors such as de-collectivization are become more important factors as the economy is moving from planned economy to market economy. This paper assesses the effects of socio-economic, demographic, institutional and climate factors on grassland use and productivity using a panel data set. The panel data compose the years from 1970s to 2000s and all prefectures in Inner Mongolia. A generalized least squares estimation method, allowing individual effects for prefecture level are applied to the examination. The effect of climate change is tested as well and the coupled socio-economic system and the natural system are investigated.

Improving rubber concrete by waste organic sulfur compounds.

PubMed

Chou, Liang-Hisng; Lin, Chun-Nan; Lu, Chun-Ku; Lee, Cheng-Haw; Lee, Maw-Tien

2010-01-01

In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly.

Bioremediation of contaminated groundwater

DOEpatents

Hazen, T.C.; Fliermans, C.B.

1994-01-01

Disclosed is an apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid (NF) is selected to simulated the growth and reproduction of indigenous subsurface microorganisms capable of degrading the contaminants; an oxygenated fluid (OF) is selected to create an aerobic environment with anaerobic pockets. NF is injected periodically while OF is injected continuously and both are extracted so that both are drawn across the plume. NF stimulates microbial colony growth; withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is acceptable. NF can be methane and OF be air, for stimulating production of methanotrophs to break down chlorohydrocarbons, especially TCE and tetrachloroethylene.

Stress Degradation Studies on Varenicline Tartrate and Development of a Validated Stability-Indicating HPLC Method

PubMed Central

Pujeri, Sudhakar S.; Khader, Addagadde M. A.; Seetharamappa, Jaldappagari

2012-01-01

A simple, rapid and stability-indicating reversed-phase liquid chromatographic method was developed for the assay of varenicline tartrate (VRT) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 μm) employing a mobile phase consisting of ammonium acetate buffer containing trifluoroacetic acid (0.02M; pH 4) and acetonitrile in gradient program mode with a flow rate of 1.0 mL min−1. The UV detector was operated at 237 nm while column temperature was maintained at 40 °C. The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness and limit of quantification. The method was found to be simple, specific, precise and accurate. Selectivity of the proposed method was validated by subjecting the stock solution of VRT to acidic, basic, photolysis, oxidative and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.1–192 μg mL−1 (R2 = 0.9994). The peaks of degradation products did not interfere with that of pure VRT. The utility of the developed method was examined by analyzing the tablets containing VRT. The results of analysis were subjected to statistical analysis. PMID:22396908

Birnessite-induced mechanochemical degradation of 2,4-dichlorophenol.

PubMed

Nasser, A; Mingelgrin, U

2014-07-01

DCP (2,4-dichlorophenol) is the key-intermediate in the synthesis of some widely used pesticides and is an EPA priority pollutant. The mechanochemical breakdown of DCP loaded on birnessite (δ-MnO2), montmorillonite saturated with Na(+) or Cu(2+) and hematite was investigated. Mechanical force was applied by grinding of mixtures of DCP and the minerals, using mortar and pestle. Grinding of DCP for 5 min with the montmorillonites or with hematite resulted in negligible degradation during grinding, while grinding with birnessite induced the immediate degradation of 90% of the loaded DCP. Incubation for 24h after grinding did result in up to 30% degradation of the DCP loaded on the other minerals tested. HPLC and LC-MS analysis revealed that the transformation of DCP yielded oligomerization products as well as partial dechlorination. DCP degradation on birnessite was accompanied with a substantial increase in the extractability of manganese from the mineral into an acidic aqueous solution, indicating that Mn(IV) in the mineral transformed into Mn(II) and that birnessite served as an electron acceptor in the transformation. The oligomerization and partial dechlorination brought about by grinding, suggest a reduction in bioavailability and toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Magnetic nanocomposites based on phosphorus-containing polymers—structural characterization and thermal analysis

NASA Astrophysics Data System (ADS)

Alosmanov, R. M.; Szuwarzyński, M.; Schnelle-Kreis, J.; Matuschek, G.; Magerramov, A. M.; Azizov, A. A.; Zimmermann, R.; Zapotoczny, S.

2018-04-01

Fabrication of magnetic nanocomposites containing iron oxide nanoparticles formed in situ within a phosphorus-containing polymer matrix as well as its structural characterization and its thermal degradation is reported here. Comparative structural studies of the parent polymer and nanocomposites were performed using FTIR spectroscopy, x-ray diffraction, and atomic force microscopy. The results confirmed the presence of dispersed iron oxide magnetic nanoparticles in the polymer matrix. The formed composite combines the properties of porous polymer carriers and magnetic particles enabling easy separation and reapplication of such polymeric carriers used in, for example, catalysis or environmental remediation. Studies on thermal degradation of the composites revealed that the process proceeds in three stages while a significant influence of the embedded magnetic particles on that process was observed in the first two stages. Magnetic force microscopy studies revealed that nanocomposites and its calcinated form have strong magnetic properties. The obtained results provide a comprehensive characterization of magnetic nanocomposites and the products of their calcination that are important for their possible applications as sorbents (regeneration conditions, processing temperature, disposal, etc).

Force degradation of orthodontic latex elastics: An in-vivo study.

PubMed

Qodcieh, Sadeq M Adel; Al-Khateeb, Susan N; Jaradat, Ziad W; Abu Alhaija, Elham S J

2017-03-01

Our objectives were to assess the force degradation of orthodontic latex elastics over 48 hours in vivo and to study the relationship between the amount of mouth opening and the degree of force decay. Fifty-two orthodontic patients wearing fixed appliances using Class II elastics were asked to wear premeasured-force 3/16-in heavy and medium intermaxillary elastics. The force amounts were measured and compared at different time intervals. Fifty percent of the force was lost after 3.9 hours for the medium elastics and after 4.9 hours for the heavy elastics. A continuous significant force drop in all elastics was seen at all time intervals (P <0.05, P <0.001). There was greater force loss in the heavy elastics compared with the medium elastics in vivo at all time intervals (P <0.001); the rates of force loss, however, were similar. Fifty percent of force degradation occurred in the first 4 to 5 hours. Because of breakage and for oral hygiene purposes, orthodontic elastics should be changed daily; otherwise, elastics can be used for 48 hours. Force decay of the elastics was correlated to the lateral distance between the maxillary canine and the mandibular first molar in occlusion. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

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

Canavan, G.H.

At low force levels stability indices depend primarily on the number of vulnerable missiles and the number of weapons on them. The index reduces to a product of the number of vulnerable missiles and the differences between normalized second and first strikes by vulnerable weapons. As the number of weapons per vulnerable missile decreases, the index rapidly approaches stability. Further reductions in vulnerable and survivable missiles and weapons do not affect stability, although they do reduce first and second strikes. Modest weapon reconstitution degrades stability significantly.

Characterization of product capture resin during microbial cultivations.

PubMed

Frykman, Scott; Tsuruta, Hiroko; Galazzo, Jorge; Licari, Peter

2006-06-01

Various bioactive small molecules produced by microbial cultivation are degraded in the culture broth or may repress the formation of additional product. The inclusion of hydrophobic adsorber resin beads to capture these products in situ and remove them from the culture broth can reduce or prevent this degradation and repression. These product capture beads are often subjected to a dynamic and stressful microenvironment for a long cultivation time, affecting their physical structure and performance. Impact and collision forces can result in the fracturing of these beads into smaller pieces, which are difficult to recover at the end of a cultivation run. Various contaminating compounds may also bind in a non-specific manner to these beads, reducing the binding capacity of the resin for the product of interest (fouling). This study characterizes resin bead binding capacity (to monitor bead fouling), and resin bead volume distributions (to monitor bead fracture) for an XAD-16 adsorber resin used to capture epothilone produced during myxobacterial cultivations. Resin fouling was found to reduce the product binding capacity of the adsorber resin by 25-50%. Additionally, the degree of resin bead fracture was found to be dependent on the cultivation length and the impeller rotation rate. Microbial cultivations and harvesting processes should be designed in such a way to minimize bead fragmentation and fouling during cultivation to maximize the amount of resin and associated product harvested at the end of a run.

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 4. Final report, October 1993-January 1995

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

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 3. Final report, October 1993-January 1995

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

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 1. Final report, October 1993-January 1995

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

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the and 13 specific high explosive test sites. The samples were screened for semi-volatile organic PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives or degradation products weremore » identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 2. Final report, October 1993-January 1995

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

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosivesmore » or degradation products were identified. Semi-volatile organic compounds were found in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 5. Final report, October 1993-January 1995

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

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

ReaxFF Study of the Oxidation of Softwood Lignin in View of Carbon Fiber Production

DOE PAGES

Beste, Ariana

2014-10-06

We investigate the oxidative, thermal conversion of softwood lignin by performing molecular dynamics simulations based on a reactive force field (ReaxFF). The lignin samples are constructed from coniferyl alcohol units, which are connected through linkages that are randomly selected from a natural distribution of linkages in softwood. The goal of this work is to simulate the oxidative stabilization step during carbon fiber production from lignin precursor. We find that at simulation conditions where stabilization reactions occur, the lignin fragments have already undergone extensive degradation. The 5-5 linkage shows the highest reactivity towards cyclization and dehydrogenation.

Hydrophobicity as a driver of MHC class I antigen processing

PubMed Central

Huang, Lan; Kuhls, Matthew C; Eisenlohr, Laurence C

2011-01-01

The forces that drive conversion of nascent protein to major histocompatibility complex (MHC) class I-restricted peptides remain unknown. We explored the fundamental property of overt hydrophobicity as such a driver. Relocation of a membrane glycoprotein to the cytosol via signal sequence ablation resulted in rapid processing of nascent protein not because of the misfolded luminal domain but because of the unembedded transmembrane (TM) domain, which serves as a dose-dependent degradation motif. Dislocation of the TM domain during the natural process of endoplasmic reticulum-associated degradation (ERAD) similarly accelerated peptide production, but in the context of markedly prolonged processing that included nonnascent species. These insights into intracellular proteolytic pathways and their selective contributions to MHC class I-restricted peptide supply, may point to new approaches in rational vaccine design. PMID:21378750

Hydrophobicity as a driver of MHC class I antigen processing.

PubMed

Huang, Lan; Kuhls, Matthew C; Eisenlohr, Laurence C

2011-04-20

The forces that drive conversion of nascent protein to major histocompatibility complex (MHC) class I-restricted peptides remain unknown. We explored the fundamental property of overt hydrophobicity as such a driver. Relocation of a membrane glycoprotein to the cytosol via signal sequence ablation resulted in rapid processing of nascent protein not because of the misfolded luminal domain but because of the unembedded transmembrane (TM) domain, which serves as a dose-dependent degradation motif. Dislocation of the TM domain during the natural process of endoplasmic reticulum-associated degradation (ERAD) similarly accelerated peptide production, but in the context of markedly prolonged processing that included nonnascent species. These insights into intracellular proteolytic pathways and their selective contributions to MHC class I-restricted peptide supply, may point to new approaches in rational vaccine design.

Effects of L-Alanine and Inosine Germinants on the Elasticity of Bacillus anthracis Spores

DTIC Science & Technology

2010-01-22

there was some scanner hysteresis and drift in the detection system, we often observed that the deflection of the free cantilever was not equal to zero...of waste products.5,35 The degradation of the spore coat resulted in a cell that could bemore easily indented by the AFMprobe, as was observed on...changes in the mechanical properties of the spore. In this work, we use atomic force microscopy (AFM) to characterize the mechanical properties of the

The degradation of the antitumor agent gemcitabine hydrochloride in an acidic aqueous solution at pH 3.2 and identification of degradation products.

PubMed

Jansen, P J; Akers, M J; Amos, R M; Baertschi, S W; Cooke, G G; Dorman, D E; Kemp, C A; Maple, S R; McCune, K A

2000-07-01

A study of the degradation kinetics of gemcitabine hydrochloride (2'-deoxy-2',2'-difluorocytidine) in aqueous solution at pH 3.2 was conducted. The degradation of gemcitabine followed pseudo first-order kinetics, and rate constants were determined at four different temperatures. These rates were used to construct an Arrhenius plot from which degradation rates at lower temperatures were extrapolated and activation energy calculated. Four major degradation products were identified. Only one of these degradation products, the uridine analogue of gemcitabine, was a known degradation product of gemcitabine and was identified by comparison with synthesized material. The other three degradation products were isolated and characterized by spectroscopic techniques. Two of these products were determined to be the diastereomeric 6-hydroxy-5, 6-dihydro-2'-deoxy-2',2'-difluorouridines, and the other product was determined to be O(6),5'-cyclo-5,6-dihydro-2'-deoxy-2', 2'-difluorouridine. The mechanisms of formation of these degradation products are discussed.

Determinants of farmers' tree planting investment decision as a degraded landscape management strategy in the central highlands of Ethiopia

NASA Astrophysics Data System (ADS)

Gessesse, B.; Bewket, W.; Bräuning, A.

2015-11-01

Land degradation due to lack of sustainable land management practices are one of the critical challenges in many developing countries including Ethiopia. This study explores the major determinants of farm level tree planting decision as a land management strategy in a typical framing and degraded landscape of the Modjo watershed, Ethiopia. The main data were generated from household surveys and analysed using descriptive statistics and binary logistic regression model. The model significantly predicted farmers' tree planting decision (Chi-square = 37.29, df = 15, P<0.001). Besides, the computed significant value of the model suggests that all the considered predictor variables jointly influenced the farmers' decision to plant trees as a land management strategy. In this regard, the finding of the study show that local land-users' willingness to adopt tree growing decision is a function of a wide range of biophysical, institutional, socioeconomic and household level factors, however, the likelihood of household size, productive labour force availability, the disparity of schooling age, level of perception of the process of deforestation and the current land tenure system have positively and significantly influence on tree growing investment decisions in the study watershed. Eventually, the processes of land use conversion and land degradation are serious which in turn have had adverse effects on agricultural productivity, local food security and poverty trap nexus. Hence, devising sustainable and integrated land management policy options and implementing them would enhance ecological restoration and livelihood sustainability in the study watershed.

Determinants of farmers' tree-planting investment decisions as a degraded landscape management strategy in the central highlands of Ethiopia

NASA Astrophysics Data System (ADS)

Gessesse, Berhan; Bewket, Woldeamlak; Bräuning, Achim

2016-04-01

Land degradation due to lack of sustainable land management practices is one of the critical challenges in many developing countries including Ethiopia. This study explored the major determinants of farm-level tree-planting decisions as a land management strategy in a typical farming and degraded landscape of the Modjo watershed, Ethiopia. The main data were generated from household surveys and analysed using descriptive statistics and a binary logistic regression model. The model significantly predicted farmers' tree-planting decisions (χ2 = 37.29, df = 15, P < 0.001). Besides, the computed significant value of the model revealed that all the considered predictor variables jointly influenced the farmers' decisions to plant trees as a land management strategy. The findings of the study demonstrated that the adoption of tree-growing decisions by local land users was a function of a wide range of biophysical, institutional, socioeconomic and household-level factors. In this regard, the likelihood of household size, productive labour force availability, the disparity of schooling age, level of perception of the process of deforestation and the current land tenure system had a critical influence on tree-growing investment decisions in the study watershed. Eventually, the processes of land-use conversion and land degradation were serious, which in turn have had adverse effects on agricultural productivity, local food security and poverty trap nexus. Hence, the study recommended that devising and implementing sustainable land management policy options would enhance ecological restoration and livelihood sustainability in the study watershed.

Laboratory evidence of MTBE biodegradation in Borden aquifer material

NASA Astrophysics Data System (ADS)

Schirmer, Mario; Butler, Barbara J.; Church, Clinton D.; Barker, James F.; Nadarajah, Nalina

2003-02-01

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.

Effects of Stable Degradation Products of Curcumin on Cancer Cell Proliferation and Inflammation.

PubMed

Sanidad, Katherine Z; Zhu, Julia; Wang, Weicang; Du, Zheyuan; Zhang, Guodong

2016-12-07

Curcumin is among the most promising dietary compounds for cancer prevention. However, curcumin rapidly degrades in aqueous buffer at physiological pH, making it difficult to understand whether the effects of curcumin are from curcumin itself or its degradation products. Here we studied the antiproliferative and anti-inflammatory effects of curcumin degradation products, including its total degradation products (a mixture containing all stable degradation products of curcumin) and bicyclopentadione (a dominant stable degradation compound of curcumin). Curcumin potently modulated cell proliferation, progression of cell cycle, and apoptosis in MC38 colon cancer cells and inhibited lipopolysaccharide (LPS)-induced inflammatory responses and NF-κB signaling in RAW 264.7 macrophage cells. In contrast, neither the total degradation products of curcumin nor bicyclopentadione had such effects. For example, after 24 h of treatment in MC38 colon cancer cells, 5 μg/mL curcumin inhibited 39.2 ± 1.8% of cell proliferation, whereas its degradation products were inactive. Together, these results suggest that the stable chemical degradation products of curcumin are not likely to play a major role in mediating the biological activities of curcumin.

Mineral induced mechanochemical degradation: the imazaquin case.

PubMed

Nasser, Ahmed; Buchanovsky, Nadia; Gerstl, Zev; Mingelgrin, Uri

2009-03-01

The potential role of mechanochemical processes in enhancing degradation of imazaquin by soil components is demonstrated. The investigated components include montmorillonite saturated with Na(+), Ca(2+), Cu(2+)and Al(3+), Agsorb (a commercial clay mix), birnessite and hematite. The mechanical force applied was manual grinding of mixtures of imazaquin and the minerals, using mortar and pestle. The degradation rates of imazaquin in these mixtures were examined as a function of the following parameters: time of grinding, herbicide load (3.9, 8.9, 16.7 and 26.6 mg imazaquin per g mineral), temperature (10, 25, 40 and 70 degrees C), acidic/basic conditions, and dry or wet grinding. Dry grinding of imazaquin for 5 min with Al-montmorillonite or with hematite resulted in 56% and 71% degradation of the imazaquin, respectively. Wet grinding slightly reduced the degradation rate with hematite and entirely cancelled the enhancing effect of grinding with Al-montmorillonite. Wet grinding in the presence of the transition metals: Ni(2+), Cu(2+), Fe(3+) added as chlorides was carried out. Addition of Cu(2+) to Na-montmorillonite loaded with imazaquin was the most effective treatment in degrading imazaquin (more than 90% of the imazaquin degraded after 5 min of grinding). In this treatment, Cu-montmorillonite formation during the grinding process was confirmed by XRD and accordingly, grinding with Cu-montmorillonite gave similar degradation values. LC-MS analysis revealed that the mechanochemical transformation of imazaquin resulted in the formation of a dimer and several breakdown products. The reported results demonstrate once again that mechanochemical procedures offer a remediation avenue applicable to soils polluted with organic contaminants.

Investigating the Affinities and Persistence of VX Nerve Agent in Environmental Matrices

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

Love, A H; Vance, A L; Reynolds, J G

2004-03-09

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity formore » an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when an inner-sphere complex was forced. No enhanced degradation occurred with goethite in small amounts water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.« less

PDL Progenitor-Mediated PDL Recovery Contributes to Orthodontic Relapse.

PubMed

Feng, L; Yang, R; Liu, D; Wang, X; Song, Y; Cao, H; He, D; Gan, Y; Kou, X; Zhou, Y

2016-08-01

Periodontal ligament (PDL) is subjected to mechanical force during physiologic activities. PDL stem /: progenitor cells are the main mesenchymal stem cells in PDL. However, how PDL progenitors participate in PDL homeostasis upon and after mechanical force is largely unknown. In this study, force-triggered orthodontic tooth movement and the following relapse were used as models to demonstrate the response of PDL progenitors and their role in PDL remodeling upon and after mechanical force. Upon orthodontic force, PDL collagen on the compression side significantly degraded, showing a broken and disorganized pattern. After force withdrawal, the degraded PDL collagen recovered during the early stage of relapse. Correspondingly, increased CD90(+) PDL progenitors with suppressed expression of type I collagen (Col-I) were observed upon orthodontic force, whereas these cells accumulated at the degradation regions and regained Col-I expression after force withdrawal during early relapse. Our results further showed that compressive force altered cell morphology and repressed collagen expression in cultured PDL progenitors, which both recovered after force withdrawal. Force withdrawal-induced recovery of collagen expression in cultured PDL progenitors could be regulated by transforming growth factor-β (TGF-β), a key molecule for tissue homeostasis and extracellular matrix remodeling. More interesting, inhibiting the regained Col-I expression in CD90(+) PDL progenitors by blocking TGF-β interrupted PDL collagen recovery and partially inhibited the early relapse. These data suggest that PDL progenitors can respond to mechanical force and may process intrinsic stability to recover to original status after force withdrawal. PDL progenitors with intrinsic stability are required for PDL recovery and consequently contribute to early orthodontic relapse, which can be regulated by TGF-β signaling. © International & American Associations for Dental Research 2016.

Electron acceptor-based regulation of microbial greenhouse gas production from thawing permafrost

NASA Astrophysics Data System (ADS)

Bak, Ebbe; Jones, Eleanor; Yde, Jacob; Hodson, Andy; Mallon, Gunnar; Fisnter, Kai

2017-04-01

Permafrost contains about 35% of the global soil organic carbon (0-3 m depth). As a consequence of global warming, the active layer thickness is steadily increasing and its organic carbon is becoming available for degradation, causing a concomitant release of CO2 and CH4. The climate forcing feedbacks of permafrost thaw are determined by the rate of organic carbon degradation and to which degree it is released as CO2 or CH4. Methane is produced under anoxic conditions, but the factors that regulate its production are poorly constrained. In this study, we investigate how CH4 production is influenced by the presence of competing anaerobic processes with focus on the role of iron and sulfate reduction. We have collected permafrost cores to 2.2 meters depth from three different lowland sites in Adventdalen on Svalbard. From these cores, we have prepared anoxic batch incubation for each 25 cm depth interval and followed the production of CO2 and CH4 as well as the iron and sulfate reduction. This approach allows us to monitor the rate of the CO2 and CH4 production as well as to investigate the correlation between CH4 production and competing anaerobic respiration processes in the active layer as well in the permafrost. These investigations are accompanied by characterization of the carbon, iron and sulfate content in the soil and will be followed by characterization of the microbial community structure. The aim of this study is to get a better understanding of how the availability of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms operating during permafrost thaw.

Validation and application of a stability-indicating HPLC method for the in vitro determination of gastric and intestinal stability of venlafaxine.

PubMed

Asafu-Adjaye, Ebenezer B; Faustino, Patrick J; Tawakkul, Mobin A; Anderson, Lawrence W; Yu, Lawrence X; Kwon, Hyojong; Volpe, Donna A

2007-04-11

Gastrointestinal stability of venlafaxine was evaluated in vitro in simulated gastric (SGF) and intestinal (SIF) fluids using a stability indicating HPLC method. The method was validated using a 5 microm Ascentis C18 column (150 mm x 4.6 mm) and mobile phase consisting of 30% acetonitrile in 20 mM potassium phosphate buffer (pH 6.5) delivered isocratically at a flow rate of 1 mL/min with UV detection at 228 nm. Venlafaxine in USP simulated gastric and intestinal fluids (0.4 mg/mL) was incubated at 37 degrees C in a shaking water bath. The gastric stability study samples were assayed at 0, 15, 30 and 60 min intervals while sampling for the intestinal stability study was at 0, 1, 2 and 3 h. System suitability determinations gave R.S.D.s of 0.68, 0.5 and 3.9% for retention factor (k'), peak area and tailing factor, respectively. The method was shown to be accurate, precise, specific, and linear over the analytical range. Intra- and inter-day precision was <5.3%. Forced degradation studies of drug substance in basic media at 70 degrees C as well as in H2O2 for 1 h and ultra-violet photostability studies at 255 and 365 nm for 24 h did not produce any detectable degradation products. Forced degradation studies of drug substance in acidic media at 70 degrees C for 1 h produced the dehydro-venlafaxine degradant. Venlafaxine was stable in SGF (pH approximately 1.2) for the 1-h incubation period and in SIF (pH 6.8) up to 3 h with <1.5% relative difference (RD) between the amount of drug added and that found for all time points. This stability experiment in simulated gastric and intestinal fluids suggests that drug loss in the gastrointestinal tract takes place by membrane permeation rather than a degradation process.

Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization.

PubMed

Tiehm, A; Nickel, K; Zellhorn, M; Neis, U

2001-06-01

The pretreatment of waste activated sludge by ultrasonic disintegration was studied in order to improve the anaerobic sludge stabilization. The ultrasound frequency was varied within a range from 41 to 3217 kHz. The impact of different ultrasound intensities and treatment times was examined. Sludge disintegration was most significant at low frequencies. Low-frequency ultrasound creates large cavitation bubbles which upon collapse initiate powerful jet streams exerting strong shear forces in the liquid. The decreasing sludge disintegration efficiency observed at higher frequencies was attributed to smaller cavitation bubbles which do not allow the initiation of such strong shear forces. Short sonication times resulted in sludge floc deagglomeration without the destruction of bacteria cells. Longer sonication brought about the break-up of cell walls, the sludge solids were distintegrated and dissolved organic compounds were released. The anaerobic digestion of waste activated sludge following ultrasonic pretreatment causing microbial cell lysis was significantly improved. There was an increase in the volatile solids degradation as well as an increase in the biogas production. The increase in digestion efficiency was proportional to the degree of sludge disintegration. To a lesser degree the deagglomeration of sludge flocs also augmented the anaerobic volatile solids degradation.

Decreased specific force and power production of muscle fibers from myostatin-deficient mice are associated with a suppression of protein degradation.

PubMed

Mendias, Christopher L; Kayupov, Erdan; Bradley, Joshua R; Brooks, Susan V; Claflin, Dennis R

2011-07-01

Myostatin (MSTN) is a member of the transforming growth factor-β superfamily of cytokines and is a negative regulator of skeletal muscle mass. Compared with MSTN(+/+) mice, the extensor digitorum longus muscles of MSTN(-/-) mice exhibit hypertrophy, hyperplasia, and greater maximum isometric force production (F(o)), but decreased specific maximum isometric force (sF(o); F(o) normalized by muscle cross-sectional area). The reason for the reduction in sF(o) was not known. Studies in myotubes indicate that inhibiting myostatin may increase muscle mass by decreasing the expression of the E3 ubiquitin ligase atrogin-1, which could impact the force-generating capacity and size of muscle fibers. To gain a greater understanding of the influence of myostatin on muscle contractility, we determined the impact of myostatin deficiency on the contractility of permeabilized muscle fibers and on the levels of atrogin-1 and ubiquitinated myosin heavy chain in whole muscle. We hypothesized that single fibers from MSTN(-/-) mice have a greater F(o), but no difference in sF(o), and a decrease in atrogin-1 and ubiquitin-tagged myosin heavy chain levels. The results indicated that fibers from MSTN(-/-) mice have a greater cross-sectional area, but do not have a greater F(o) and have a sF(o) that is significantly lower than fibers from MSTN(+/+) mice. The extensor digitorum longus muscles from MSTN(-/-) mice also have reduced levels of atrogin-1 and ubiquitinated myosin heavy chain. These findings suggest that myostatin inhibition in otherwise healthy muscle increases the size of muscle fibers and decreases atrogin-1 levels, but does not increase the force production of individual muscle fibers.

An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain.

PubMed

Wahab, Siti Waznah; Bister, Dirk; Sherriff, Martyn

2014-02-01

This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces force delivery and tensile strength of exposed chains.

Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole.

PubMed

Hengsawas Surasarang, Soraya; Keen, Justin M; Huang, Siyuan; Zhang, Feng; McGinity, James W; Williams, Robert O

2017-05-01

The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ-polymer binary mixtures generated from Flory-Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80 °C for 5 min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80 °C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon ® VA 64, degraded at 180 °C and 140 °C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon ® VA 64, Soluplus ® and Eudragit ® E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon ® VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon ® VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.

"Dark" Singlet Oxygen and Electron Paramagnetic Resonance Spin Trapping as Convenient Tools to Assess Photolytic Drug Degradation.

PubMed

Persich, Peter; Hostyn, Steven; Joie, Céline; Winderickx, Guy; Pikkemaat, Jeroen; Romijn, Edwin P; Maes, Bert U W

2017-05-01

Forced degradation studies are an important tool for a systematic assessment of decomposition pathways and identification of reactive sites in active pharmaceutical ingredients (APIs). Two methodologies have been combined in order to provide a deeper understanding of singlet oxygen-related degradation pathways of APIs under light irradiation. First, we report that a "dark" singlet oxygen test enables the investigation of drug reactivity toward singlet oxygen independently of photolytic irradiation processes. Second, the photosensitizing properties of the API producing the singlet oxygen was proven and quantified by spin trapping and electron paramagnetic resonance analysis. A combination of these techniques is an interesting addition to the forced degradation portfolio as it can be used for (1) revealing unexpected degradation pathways of APIs due to singlet oxygen, (2) clarifying photolytic drug-drug interactions in fixed-dose combinations, and (3) synthesizing larger quantities of hardly accessible oxidative drug degradants. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

A Stability-Indicating HPLC Method for the Determination of Fingolimod in Pharmaceutical Dosage Forms.

PubMed

Souri, Effat; Zargarpoor, Mohammad; Mottaghi, Siavash; Ahmadkhaniha, Reza; Kebriaeezadeh, Abbas

2015-01-01

Fingolimod is an immunosuppressive agent which is used for the prophylaxis of organ transplantation rejection or multiple sclerosis treatment. In this study, systematic forced degradation studies on fingolimod bulk powder were performed to develop a stability-indicating HPLC method. Separation of fingolimod and its degradation products was achieved on a Nova-Pak C8 column. The mobile phase was a mixture of potassium dihydrogenphosphate 50 mM (pH 3.0) and acetonitrile (45:55, v/v) at a flow rate of 1 ml/min. The proposed method was linear in the range of 0.125-20 μg mL(-1). The within-day and between-day coefficients of variation were in the range of 0.6-1.2%. The developed method was successfully applied for the determination of the fingolimod amount in pharmaceutical dosage forms.

Sarcomere length influences postmortem proteolysis of excised bovine semitendinosus muscle.

PubMed

Weaver, A D; Bowker, B C; Gerrard, D E

2008-08-01

The interaction between sarcomere length and postmortem proteolysis as related to meat tenderness is not clear. The extent of thick and thin filament overlap alters actomyosin binding and may alter substrate availability during aging-induced tenderization. The objective of this study was to determine the influence of sarcomere length on proteolytic degradation in beef. Strips from bovine semitendinosus were either stretched 40% and restrained or allowed to shorten unrestrained in an ice bath. After rigor completion, 0.6-cm cross sections were fabricated and were randomly assigned to 2, 4, 7, or 10 d of aging treatments. Myofibrils were isolated for sarcomere length determination. Samples were collected and frozen for shear force analysis, and muscle proteins were extracted for SDS-PAGE and Western blotting analyses to determine troponin T (TnT) proteolysis. Sarcomere length was greater (P < 0.01) in stretched muscle samples compared with shortened samples (2.57 vs. 1.43 microm, respectively). Correspondingly, shear force values were greater (P < 0.05) in shortened samples than stretched samples. Western blots revealed the presence of 3 major intact TnT bands that diminished with time postmortem and 4 bands (TnT degradation products) that accumulated during postmortem storage. Quantification of intact TnT showed increased (P < 0.05) proteolysis at 4 and 7 d postmortem in samples with long sarcomeres. By 10 d, only traces of the greatest molecular weight intact TnT band were evident in both shortened and stretched samples, suggesting this TnT band may be more susceptible to proteolysis than other intact TnT bands. Degradation products of TnT appeared earlier postmortem in samples with long sarcomeres. The 30-kDa TnT fragment appeared after 7 d of postmortem storage in samples with long sarcomeres but not until 10 d in muscle containing short sarcomeres. Collectively, these data show that postmortem TnT proteolysis is sarcomere length-dependent and suggest that thick and thin filament overlap may influence the postmortem aging process in beef.

Thermal degradation of aqueous 2-aminoethylethanolamine in CO2 capture; identification of degradation products, reaction mechanisms and computational studies.

PubMed

Saeed, Idris Mohamed; Lee, Vannajan Sanghiran; Mazari, Shaukat Ali; Si Ali, B; Basirun, Wan Jeffrey; Asghar, Anam; Ghalib, Lubna; Jan, Badrul Mohamed

2017-01-01

Amine degradation is the main significant problems in amine-based post-combustion CO 2 capture, causes foaming, increase in viscosity, corrosion, fouling as well as environmental issues. Therefore it is very important to develop the most efficient solvent with high thermal and chemical stability. This study investigated thermal degradation of aqueous 30% 2-aminoethylethanolamine (AEEA) using 316 stainless steel cylinders in the presence and absence of CO 2 for 4 weeks. The degradation products were identified by gas chromatography mass spectrometry (GC/MS) and liquid chromatography-time-of-flight-mass spectrometry (LC-QTOF/MS). The results showed AEEA is stable in the absence of CO 2 , while in the presence of CO 2 AEEA showed to be very unstable and numbers of degradation products were identified. 1-(2-Hydroxyethyl)-2-imidazolidinone (HEIA) was the most abundance degradation product. A possible mechanism for the thermal degradation of AEEA has been developed to explain the formation of degradation products. In addition, the reaction energy of formation of the most abundance degradation product HEIA was calculated using quantum mechanical calculation.

The effects of grassland degradation on plant diversity, primary productivity, and soil fertility in the alpine region of Asia's headwaters.

PubMed

Wang, Xuexia; Dong, Shikui; Yang, Bing; Li, Yuanyuan; Su, Xukun

2014-10-01

A 3-year survey was conducted to explore the relationships among plant composition, productivity, and soil fertility characterizing four different degradation stages of an alpine meadow in the source region of the Yangtze and Yellow Rivers, China. Results showed that plant species diversity, productivity, and soil fertility of the top 30-cm soil layer significantly declined with degradation stages of alpine meadow over the study period. The productivity of forbs significantly increased with degradation stages, and the soil potassium stock was not affected by grassland degradation. The vegetation composition gradually shifted from perennial graminoids (grasses and sedges) to annual forbs along the degradation gradient. The abrupt change of response in plant diversity, plant productivity, and soil nutrients was demonstrated after heavy grassland degradation. Moreover, degradation can indicate plant species diversity and productivity through changing soil fertility. However, the clear relationships are difficult to establish. In conclusion, degradation influenced ecosystem function and services, such as plant species diversity, productivity, and soil carbon and nitrogen stocks. Additionally, both plant species diversity and soil nutrients were important predictors in different degradation stages of alpine meadows. To this end, heavy degradation grade was shown to cause shift of plant community in alpine meadow, which provided an important basis for sustaining ecosystem function, manipulating the vegetation composition of the area and restoring the degraded alpine grassland.

N/Fe-TiO2 doped nanoparticles loaded on bentonite for increased photocatalytic activity for the degradation of organic pollutants

NASA Astrophysics Data System (ADS)

Espenilla, Mel Bryan L.; Magyaya, Ryan Carl S.; Conato, Marlon T.

2018-05-01

Photocatalyst materials based on Philippine bentonite-titanium oxide composites and their ability to degrade organic pollutants is reported. Nanosized-titanium dioxide (TiO2) was synthesized by sol-gel method from titanium tetraisopropoxide. This was then incorporated in the Philippine bentonite via hydrothermal methods. In order to shift the absorbance of the TiO2 to the visible region doping was done using iron and nitrogen ions. The hydrodynamic radius of the synthesized TiO2 was analyzed using a zeta-sizer and was found to be around 70 nm. The photocatalytic efficiency of the TiO2/bentonite, N-TiO2/bentonite, Fe-TiO2/bentonite and N-Fe-TiO2/bentonite was evaluated using a photocatalytic reactor. It was found out that the N-Fe-TiO2/bentonite to be the most efficient with 22% degradation of the model pollutant after 80 minutes. FT-IR analysis was done to determine the bonding of the different components. Scanning electron microscopy and atomic force microscopy analysis was also performed to characterize the products.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis

NASA Astrophysics Data System (ADS)

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. > 9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and δ13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched δ13C values compared to the upgradient mean. In addition, δ13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis.

PubMed

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. >9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and delta13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched delta13C values compared to the upgradient mean. In addition, delta13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Raman spectroscopy and capillary zone electrophoresis for the analysis of degradation processes in commercial effervescent tablets containing acetylsalicylic acid and ascorbic acid.

PubMed

Neuberger, Sabine; Jooß, Kevin; Flottmann, Dirk; Scriba, Gerhard; Neusüß, Christian

2017-02-05

In order to ensure the stability of pharmaceutical products appropriate manufacturing and storage conditions are required. In general, the degradation of active pharmaceutical ingredients (APIs) and subsequent formation of degradation products affect the pharmaceutical quality. Thus, a fast and effective detection and characterization of these substances is mandatory. Here, the applicability of Raman spectroscopy and CZE for the characterization of the degradation of effervescent tablets containing acetylsalicylic acid (ASA) and ascorbic acid (AA) was evaluated. Therefore, a degradation study was performed analyzing tablets from two different manufacturers at varying conditions (relative humidity (RH) 33%, 52% and 75% at 30°C). Raman spectroscopy combined with principal component analysis could be successfully applied for the fast and easy discrimination of non-degraded and degraded effervescent tablets after a storage period of approximately 24h (RH 52%). Nevertheless, a clear identification or quantification of APIs and degradation products within the analyzed tablets was not possible, i.a. due to missing reference materials. CZE-UV enabled the quantification of the APIs (ASA, AA) and related degradation products (salicylic acid (SA); semi-quantitative also mono- and diacetylated AA) within the complex tablet mixtures. The higher the RH, the faster the degradation of ASA and AA as well as the formation of the degradation products. Mono- and diacetylated AA are major primary degradation products of AA for the applied effervescent tablets. A significant degradation of the APIs was detected earlier by CZE (6-12h, RH 52%) than by Raman spectroscopy. Summarized, Raman spectroscopy is well-suited as quick test to detect degradation of these tablets and CZE can be utilized for further detailed characterization and quantification of specific APIs and related degradation products. Copyright © 2016 Elsevier B.V. All rights reserved.

Structures of Degradation Products and Degradation Pathways of Aflatoxin B1 by High-Voltage Atmospheric Cold Plasma (HVACP) Treatment.

PubMed

Shi, Hu; Cooper, Bruce; Stroshine, Richard L; Ileleji, Klein E; Keener, Kevin M

2017-08-02

High-voltage atmospheric cold plasma (HVACP) is a novel nonthermal decontamination technology that has potential for use in the food industry. In this study, HVACP was applied to treat pure aflatoxin B 1 (AFB 1 ) powder on a glass slide. AFB 1 was degraded by 76% using a 5 min HVACP treatment in air having 40% relative humidity. The degradation products of AFB 1 were separated, and their molecular formulas were elucidated using liquid-chromatography time-of-flight mass spectrometry (HPLC-TOF-MS). Six main degradation products were observed. The structures of the degradation products were further clarified via orbitrap mass spectrometry by means of fragmentation of the parental ions. Two degradation pathways were proposed on the basis of the structure of the degradation products. Among the six degradation products, two were ozonolysis products of AFB 1 . The appearance of the other four degradation products indicates that AFB 1 was degraded by other reactive species besides ozone that were generated during HVACP treatment. Reactive oxygen gas species are suggested as the major agents for aflatoxin degradation during HVACP treatment. Two degradation pathways of AFB 1 by HVACP treatment were proposed. One pathway involves reactions in which H • , OH • , CHO • radicals are added. The other involves epoxidation by HO 2 • radicals and oxidation of AFB 1 by the combined effects of the oxidative species OH • , H 2 O 2 , and O 3 . According to the structure-bioactivity relationship of AFB 1 , the bioactivity of the AFB 1 samples subjected to HVACP treatment is significantly reduced because of the disappearance of the C8═C9 double bond in the furofuran ring in all of the major degradation products as well as the modification of the lactone ring, cyclopentanone, and the methoxyl group.

Evaluation of the effects of aging in synthetic saliva solution of both commercial and silanized Nd-Fe-B magnets for dental application

NASA Astrophysics Data System (ADS)

Fabiano, F.; Puliafito, V.; Calabrese, L.; Borsellino, C.; Bonaccorsi, L. M.; Giordano, A.; Fabiano, V.; Cordasco, G.

2016-04-01

Neodymium-iron-boron magnets are able to ensure a magnetic flux with high maximum energy product also at miniaturized size. In the past, due to their marked corrosion in saliva they were unsuccessfully implemented in orthodontic systems. Thereby, we propose a multi-layered organic-inorganic coating able to supply anticorrosion resistance, wear resistance and durability to the whole assembly. We evaluated the influence on the magnetic force of commercial nickel plated and silanized Nd-Fe-B during aging time in synthetic Fusayama saliva. Two magnets based-micromagnetic simulations were performed in order to analyze the magnetic field generated which is linked to the magnetic force. Our key results underline that the proposed hybrid coating does not affect the magnetic force of Nd-Fe-B magnets, moreover, preventing corrosion degradation in aggressive solution. Thus the limiting aspects avoiding the use of Nd-Fe-B magnets for orthodontic and prosthodontic applications can be overcome by using silane agents as surface coating.

Mussel-inspired functionalization of electrochemically exfoliated graphene: Based on self-polymerization of dopamine and its suppression effect on the fire hazards and smoke toxicity of thermoplastic polyurethane.

PubMed

Cai, Wei; Wang, Junling; Pan, Ying; Guo, Wenwen; Mu, Xiaowei; Feng, Xiaming; Yuan, Bihe; Wang, Xin; Hu, Yuan

2018-06-15

The suppression effect of graphene in the fire hazards and smoke toxicity of polymer composites has been seriously limited by both mass production and weak interfacial interaction. Though the electrochemical preparation provides an available approach for mass production, exfoliated graphene could not strongly bond with polar polymer chains. Herein, mussel-inspired functionalization of electrochemically exfoliated graphene was successfully processed and added into polar thermoplastic polyurethane matrix (TPU). As confirmed by SEM patterns of fracture surface, functionalized graphene possessing abundant hydroxyl could constitute a forceful chains interaction with TPU. By the incorporation of 2.0 wt % f-GNS, peak heat release rate (pHRR), total heat release (THR), specific extinction area (SEA), as well as smoke produce rate (SPR) of TPU composites were approximately decreased by 59.4%, 27.1%, 31.9%, and 26.7%, respectively. A probable mechanism of fire retardant was hypothesized: well-dispersed f-GNS constituted tortuous path and hindered the exchange process of degradation product with barrier function. Large quantities of degradation product gathered round f-GNS and reacted with flame retardant to produce the cross-linked and high-degree graphited residual char. The simple functionalization for electrochemically exfoliated graphene impels the application of graphene in the fields of flame retardant composites. Copyright © 2018 Elsevier B.V. All rights reserved.

A study of the degradation of organophosphorus pesticides in river waters and the identification of their degradation products by chromatography coupled with mass spectrometry.

PubMed

Zhao, Xueheng; Hwang, Huey-Min

2009-05-01

The degradation of selected organophosphorus pesticides (OPs), i.e., malathion and parathion, in river water, has been studied with solar simulator irradiation. The degradation of OPs and formation of degradation products were determined by chromatography coupled with mass spectrometry analysis. The effect of a photosensitizer, i.e., riboflavin, on the photolysis of OPs in a river-water environment was examined. There was no significant increase in the degradation rate in the presence of the photosensitizer. Degradation products of the OPs were identified with gas chromatography coupled with mass spectrometry (GC-MS) after derivatization by pentafluorobenzyl bromide (PFBB) and with high-performance liquid chromatography-mass spectrometry (HPLC-MS) with electrospray (ESI) or atomospheric pressure chemical ionization (APCI). Malaoxon, paraoxon, 4-nitrophenol, aminoparathion, O,O-dimethylthiophosphoric acid, and O,O-dimethyldithiophosphoric acid, have been separated and identified as the degradation products of malathion and parathion after photolysis in river water. Based on the identified transformation products, a rational degradation pathway in river water for both OPs is proposed. The identities of these products can be used to evaluate the toxic effects of the OPs and their transformation products on natural environments.

A Stability-Indicating HPLC Method for the Determination of Fingolimod in Pharmaceutical Dosage Forms

PubMed Central

Souri, Effat; Zargarpoor, Mohammad; Mottaghi, Siavash; Ahmadkhaniha, Reza; Kebriaeezadeh, Abbas

2015-01-01

Fingolimod is an immunosuppressive agent which is used for the prophylaxis of organ transplantation rejection or multiple sclerosis treatment. In this study, systematic forced degradation studies on fingolimod bulk powder were performed to develop a stability-indicating HPLC method. Separation of fingolimod and its degradation products was achieved on a Nova-Pak C8 column. The mobile phase was a mixture of potassium dihydrogenphosphate 50 mM (pH 3.0) and acetonitrile (45:55, v/v) at a flow rate of 1 ml/min. The proposed method was linear in the range of 0.125–20 μg mL−1. The within-day and between-day coefficients of variation were in the range of 0.6–1.2%. The developed method was successfully applied for the determination of the fingolimod amount in pharmaceutical dosage forms. PMID:26839803

Estimation of tool wear during CNC milling using neural network-based sensor fusion

NASA Astrophysics Data System (ADS)

Ghosh, N.; Ravi, Y. B.; Patra, A.; Mukhopadhyay, S.; Paul, S.; Mohanty, A. R.; Chattopadhyay, A. B.

2007-01-01

Cutting tool wear degrades the product quality in manufacturing processes. Monitoring tool wear value online is therefore needed to prevent degradation in machining quality. Unfortunately there is no direct way of measuring the tool wear online. Therefore one has to adopt an indirect method wherein the tool wear is estimated from several sensors measuring related process variables. In this work, a neural network-based sensor fusion model has been developed for tool condition monitoring (TCM). Features extracted from a number of machining zone signals, namely cutting forces, spindle vibration, spindle current, and sound pressure level have been fused to estimate the average flank wear of the main cutting edge. Novel strategies such as, signal level segmentation for temporal registration, feature space filtering, outlier removal, and estimation space filtering have been proposed. The proposed approach has been validated by both laboratory and industrial implementations.

Electrical condition monitoring method for polymers

DOEpatents

Watkins, Jr. Kenneth S.; Morris, Shelby J.; Masakowski, Daniel D.; Wong, Ching Ping; Luo, Shijian

2010-02-16

An electrical condition monitoring method utilizes measurement of electrical resistivity of a conductive composite degradation sensor to monitor environmentally induced degradation of a polymeric product such as insulated wire and cable. The degradation sensor comprises a polymeric matrix and conductive filler. The polymeric matrix may be a polymer used in the product, or it may be a polymer with degradation properties similar to that of a polymer used in the product. The method comprises a means for communicating the resistivity to a measuring instrument and a means to correlate resistivity of the degradation sensor with environmentally induced degradation of the product.

21 CFR 864.7320 - Fibrinogen/fibrin degradation products assay.

Code of Federal Regulations, 2010 CFR

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...

Non-Colocated Kinesthetic Display Limits Compliance Discrimination in the Absence of Terminal Force Cues.

PubMed

Brown, Jeremy D; Shelley, Mackenzie K; Gardner, Duane; Gansallo, Emmanuel A; Gillespie, R Brent

2016-01-01

An important goal of haptic display is to make available the action/reaction relationships that define interactions between the body and the physical world. While in physical world interactions reaction cues invariably impinge on the same part of the body involved in action (reaction and action are colocated), a haptic interface is quite capable of rendering feedback to a separate body part than that used for producing exploratory actions (non-colocated action and reaction). This most commonly occurs with the use of vibrotactile display, in which a cutaneous cue has been substituted for a kinesthetic cue (a kind of sensory substitution). In this paper, we investigate whether non-colocated force and displacement cues degrade the perception of compliance. Using a custom non-colocated kinesthetic display in which one hand controls displacement and the other senses force, we ask participants to discriminate between two virtual springs with matched terminal force and adjustable non-linearity. An additional condition includes one hand controlling displacement while the other senses force encoded in a vibrotactile cue. Results show that when the terminal force cue is unavailable, and even when sensory substitution is not involved, non-colocated kinesthetic displays degrade compliance discrimination relative to colocated kinesthetic displays. Compliance discrimination is also degraded with vibrotactile display of force. These findings suggest that non-colocated kinesthetic displays and, likewise, cutaneous sensory substitution displays should be avoided when discrimination of compliance is necessary for task success.

The history of environmental change and adaptation in eastern Saloum-Senegal—Driving forces and perceptions

NASA Astrophysics Data System (ADS)

Mbow, Cheikh; Mertz, Ole; Diouf, Awa; Rasmussen, Kjeld; Reenberg, Anette

2008-12-01

Environmental change in the Sahel-Sudan zone of West Africa has been a major issue in development debates over the last decades. Using remote sensing based land cover change analysis, archival data, national and international statistical data, and household interviews, we analyze the drivers of environmental change in Eastern Saloum in Central East Senegal as well as the local perceptions of these changes and adaptation. Being part of the ground nut basin, Eastern Saloum has witnessed rapid environmental degradation caused by the conversion of forest and savanna areas to agricultural land during the last 20-30 years and by a combination of decline in precipitation, soil degradation, a diversity of policies with little concern for the environment, fluctuating markets and population pressure. Farmers perceive the environmental change mainly as land degradation and poor soil fertility, though recent extensification of agriculture counters this effect and has led to increased vegetation cover in marginal areas. They identified erratic climate, agricultural policies, insufficient food production and desire to increase income as the main drivers of change in the area. We conclude that while climate variability has influenced environmental change in the area, various types of State interventions in agriculture and global market fluctuations appear to have been the main underlying causes of environmental degradation.

Vitamin C degradation products and pathways in the human lens.

PubMed

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 < 0.05). In water-insoluble proteins, only 3-deoxythreosone and threosone were detected, whereby the level of 3-deoxythreosone was ∼20 times higher than the level of threosone. The identification of 3-deoxythreosone as the major 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.

Effects of rotor model degradation on the accuracy of rotorcraft real time simulation

NASA Technical Reports Server (NTRS)

Houck, J. A.; Bowles, R. L.

1976-01-01

The effects are studied of degrading a rotating blade element rotor mathematical model to meet various real-time simulation requirements of rotorcraft. Three methods of degradation were studied: reduction of number of blades, reduction of number of blade segments, and increasing the integration interval, which has the corresponding effect of increasing blade azimuthal advance angle. The three degradation methods were studied through static trim comparisons, total rotor force and moment comparisons, single blade force and moment comparisons over one complete revolution, and total vehicle dynamic response comparisons. Recommendations are made concerning model degradation which should serve as a guide for future users of this mathematical model, and in general, they are in order of minimum impact on model validity: (1) reduction of number of blade segments, (2) reduction of number of blades, and (3) increase of integration interval and azimuthal advance angle. Extreme limits are specified beyond which the rotating blade element rotor mathematical model should not be used.

Degradation of the performance of an epoxy-impregnated REBCO solenoid due to electromagnetic forces

NASA Astrophysics Data System (ADS)

Matsuda, T.; Okamura, T.; Hamada, M.; Matsumoto, S.; Ueno, T.; Piao, R.; Yanagisawa, Y.; Maeda, H.

2018-03-01

Recently, degradation of a high-field REBCO coil due to strong electromagnetic forces, has been identified. This issue is related to a conductor movement, forming a kink in the conductor body, and hence epoxy impregnation should be effective to prevent it. The purpose of this paper is to examine the effect of epoxy impregnation on the electromagnetic force-induced degradation of a REBCO coil. We made an epoxy impregnated solenoid coil and charged it at 4.2 K in an external field of 11 T. A notable characteristic behavior, which is different from that of a dry or paraffin impregnated coil, was observed in the coil's performance. The coil did not show any normal voltage below 408 A, at 65% on the coil load line, but it showed a sudden voltage jump at 408 A, resulted from a sudden fracture of the REBCO conductor. The outward bending, combined with a strong circumferential stress, caused the REBCO layer to fracture. Although epoxy impregnation is effective to suppress a conductor movement inside the winding, avoiding self-supported sites at a coil edge is required to eliminate degradation of the thin and flexible REBCO conductor.

Trapping charges at grain boundaries and degradation of CH3NH3Pb(I1-x Br x )3 perovskite solar cells.

PubMed

Nguyen, Bich Phuong; Kim, Gee Yeong; Jo, William; Kim, Byeong Jo; Jung, Hyun Suk

2017-08-04

The electrical properties of CH 3 NH 3 Pb(I 1-x Br x ) 3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

Trapping charges at grain boundaries and degradation of CH3NH3Pb(I1-x Br x )3 perovskite solar cells

NASA Astrophysics Data System (ADS)

Phuong Nguyen, Bich; Kim, Gee Yeong; Jo, William; Kim, Byeong Jo; Jung, Hyun Suk

2017-08-01

The electrical properties of CH3NH3Pb(I1-x Br x )3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

Reactive Minerals and Dechlorinating Communities: Mechanisms Governing the Degradation of Chlorinated Ethenes during Back Diffusion from Low Permeability Zones in Aerobic and Anaerobic Environments

NASA Astrophysics Data System (ADS)

Berns, E. C.; Zeng, R.; Singh, H.; Valocchi, A. J.; Sanford, R. A.; Strathmann, T. J.; Schaefer, C. E.; Werth, C. J.

2017-12-01

Low permeability zones (LPZs) comprised of silts and clays, and contaminated with chlorinated ethenes, can act as a long term source of contaminated groundwater by diffusion into adjacent high permeability zones (HPZs). Following initial remediation efforts, chlorinated ethenes that have diffused into LPZs will back diffuse and recontaminate HPZs. Because chlorinated ethenes are known to cause cancer and damage the liver, kidneys, and central nervous system, it is important to understand how they degrade in natural systems and how to model their fate and transport. Previous work has shown that anaerobic hydrogenolysis reactions are facilitated by both dechlorinating microorganisms and reactive minerals. Abiotic dichloro-elimination reactions with reactive minerals can also degrade chlorinated ethenes to acetylene, albeit at slower rates than biotic processes. More recently, studies have explored aerobic abiotic degradation of chlorinated ethenes to formate, glycolate, and carbon dioxide. This study focuses on these biotic and abiotic reactions and their contributions to chlorinated ethene degradation under aerobic and anaerobic conditions at the LPZ/HPZ interface. A two-dimensional flow cell was constructed to model this interface using clay and sand from Pease Air Force Base. The clay was inoculated with a dechlorinating enrichment culture. Tenax adsorbent beads equilibrated with trichloroethylene (TCE) were used as a chlorinated ethene source zone at the base of the clay. TCE and its degradation products diffused from the clay into the sand, where they were removed from the flow cell by groundwater at a rate of 50 mL/day. Volatile compounds were trapped in a sample loop and removed every 48 hours for analysis by GC-FID. Organic and inorganic ions in the effluent were analyzed on the HPLC and IC. The experiment was terminated by freezing the flow cell, and chemical profiles through the flow cell material were created to show the spatial distribution of degradation products. Chemical profiles through the clay were modeled using a 1D diffusion-reaction model, and the contributions of abiotic and biotic processes to TCE degradation were determined. The model and experimental data lend insights into transformation processes that control the fate and transport of chlorinated ethenes at contaminated sites.

75 FR 73108 - Guidance for Industry on Abbreviated New Drug Applications: Impurities in Drug Products...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-29

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2010-D-0584... Products.'' This guidance updates recommendations regarding degradation products and updates the draft... information on listing of degradation products, setting acceptance criteria, and qualifying degradation...

Identification and formation mechanism of individual degradation products in lithium-ion batteries studied by liquid chromatography/electrospray ionization mass spectrometry and atmospheric solid analysis probe mass spectrometry.

PubMed

Takeda, Sahori; Morimura, Wataru; Liu, Yi-Hung; Sakai, Tetsuo; Saito, Yuria

2016-08-15

Improvement of lithium ion batteries (LIBs) in terms of performance and robustness requires good understanding of the reaction processes. The analysis of the individual degradation products in LIB electrolytes and on the surface of the electrodes provides vital information in this regard. In this study, mass spectrometric analytical methods were utilized for the identification of the individual degradation products. The degradation products in the electrolytes recovered from cycle-tested cells were separated by liquid chromatography (LC) and their mass spectrometric analysis was conducted by electrospray ionization mass spectrometry (ESI-MS). For identification of degradation products on the surface of electrodes, atmospheric solid analysis probe (ASAP)-MS analysis was conducted by time-of-flight mass spectrometry with an ASAP probe and an atmospheric pressure chemical ionization source. The degradation products in the electrolytes, namely carbonate oligomers and organophosphates, were identified simultaneously by LC/ESI-MS. Their formation mechanisms were estimated, which explain their different compositions at different temperatures. One degradation product was found on the anode surface by ASAP-MS, and its formation mechanism was explained similarly to those in the electrolyte. The results suggest that the electrolyte degradation is correlated with the formation of a solid electrolyte interphase, which is an important factor in the performance of LIBs. We expect that further investigation of the degradation products by LC/ESI-MS and ASAP-MS will be helpful for studying their degradation processes in LIBs. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Effective passivation of exfoliated black phosphorus transistors against ambient degradation.

PubMed

Wood, Joshua D; Wells, Spencer A; Jariwala, Deep; Chen, Kan-Sheng; Cho, EunKyung; Sangwan, Vinod K; Liu, Xiaolong; Lauhon, Lincoln J; Marks, Tobin J; Hersam, Mark C

2014-12-10

Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation is further supported by the observation that BP degradation occurs more rapidly on hydrophobic octadecyltrichlorosilane self-assembled monolayers and on H-Si(111) versus hydrophilic SiO2. For unencapsulated BP field-effect transistors, the ambient degradation causes large increases in threshold voltage after 6 h in ambient, followed by a ∼ 10(3) decrease in FET current on/off ratio and mobility after 48 h. Atomic layer deposited AlOx overlayers effectively suppress ambient degradation, allowing encapsulated BP FETs to maintain high on/off ratios of ∼ 10(3) and mobilities of ∼ 100 cm(2) V(-1) s(-1) for over 2 weeks in ambient conditions. This work shows that the ambient degradation of BP can be managed effectively when the flakes are sufficiently passivated. In turn, our strategy for enhancing BP environmental stability will accelerate efforts to implement BP in electronic and optoelectronic applications.

Airway symptoms and lung function in pipelayers exposed to thermal degradation products from MDI-based polyurethane.

PubMed Central

Jakobsson, K; Kronholm-Diab, K; Rylander, L; Hagmar, L

1997-01-01

OBJECTIVES: To study the prevalence of symptoms from the eyes and the upper and lower respiratory tract, lung function, and immunological sensitisation towards isocyanates in pipelayers exposed to thermal degradation products from methylene diphenyl diisocyanate (MDI)-based polyurethane (PUR). MATERIAL AND METHODS: 50 presently active and 113 formerly active pipelayers were examined. Also, 65 unexposed workers were investigated for comparison. The one year prevalence of symptoms and smoking history (questionnaire data), lung function (vital capacity (VC) and forced expiratory volume in one second (FEV1), and atopy (positive skin prick tests towards standard allergens) were assessed among pipelayers and controls. For the pipelayers, the presence of work related symptoms and estimates of isocyanate and welding exposure were obtained from an interview. Skin prick tests towards specific isocyanate antigens and determinations of IgE-MDI and IgG-MDI in serum were also performed. RESULTS: The prevalence of episodes (more than once a month) of irritative eye symptoms, congestion of the nose, and soreness or dryness in the throat was much higher among the PUR pipelayers than among the controls. Most of the pipelayers with symptoms reported that these had started and occurred in relation to the PUR welding tasks. Presently active pipelayers with recent high PUR exposure showed a significant reduction of FEV1 compared with the controls. The estimated reduction, adjusted for smoking, was -0.3 l (P = 0.04). There was no confounding effect of ordinary welding. None of the pipelayers showed positive skin prick reactions against the specific isocyanate antigens used, or positive IgE-MDI, and only two had increased IgG-MDI. CONCLUSIONS: The findings indicate that exposure to thermal degradation products from MDI-based polyurethane has adverse effects on the mucous membranes and airways. PMID:9470895

Validated stability-indicating spectrophotometric methods for the determination of Silodosin in the presence of its degradation products.

PubMed

Boltia, Shereen A; Abdelkawy, Mohammed; Mohammed, Taghreed A; Mostafa, Nahla N

2018-09-05

Five simple, rapid, accurate, and precise spectrophotometric methods are developed for the determination of Silodosin (SLD) in the presence of its acid induced and oxidative induced degradation products. Method A is based on dual wavelength (DW) method; two wavelengths are selected at which the absorbance of the oxidative induced degradation product is the same, so wavelengths 352 and 377 nm are used to determine SLD in the presence of its oxidative induced degradation product. Method B depends on induced dual wavelength theory (IDW), which is based on selecting two wavelengths on the zero-order spectrum of SLD where the difference in absorbance between them for the spectrum of acid induced degradation products is not equal to zero so through multiplying by the equality factor, the absorption difference is made to be zero for the acid induced degradation product while it is still significant for SLD. Method C is first derivative ( 1 D) spectrophotometry of SLD and its degradation products. Peak amplitudes are measured at 317 and 357 nm. Method D is ratio difference spectrophotometry (RD) where the drug is determined by the difference in amplitude between two selected wavelengths, at 350 and 277 nm for the ratio spectrum of SLD and its acid induced degradation products while for the ratio spectrum of SLD and its oxidative induced degradation products the difference in amplitude is measured at 345 and 292 nm. Method E depends on measuring peak amplitudes of the first derivative of the ratio ( 1 DD) where peak amplitudes are measured at 330 nm in the presence of the acid induced degradation product and measured by peak to peak technique at 326 and 369 nm in the presence of the oxidative induced degradation product. The proposed methods are validated according to ICH recommendations. The calibration curves for all the proposed methods are linear over a concentration range of 5-70 μg/mL. The selectivity of the proposed methods was tested using different laboratory prepared mixtures of SLD with either its acid induced or oxidative induced degradation products showing specificity of SLD with accepted recovery values. The proposed methods have been successfully applied to the analysis of SLD in pharmaceutical dosage forms without interference from additives. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous production of laccase and degradation of bisphenol A with Trametes versicolor cultivated on agricultural wastes.

PubMed

Zeng, Shengquan; Zhao, Jie; Xia, Liming

2017-08-01

Solid state fermentation with Trametes versicolor was carried out on agricultural wastes containing bisphenol A (BPA). It was found that BPA degradation was along with the occurrence of laccase production, and wheat bran and corn straw were identified as suitable mixed substrates for laccase production. In the process of BPA degradation with T. versicolor, laccase activity increased rapidly at the 6th-10th day after inoculation. Moreover, BPA can enhance the production of laccase. After 10 days of fermentation, degradation rate of BPA exceeded 90% without the usage of mediators ABTS and acetosyringone at pH 4.0-8.0. In addition, metal ions did not affect the BPA degradation with T. versicolor. In vitro, the optimum pH range of BPA degradation with laccase was in the acidic region with the optimal performance of pH 5.0. Metal ions Cu 2+ , Zn 2+ , and Co 2+ showed little effect on BPA degradation. However, Fe 3+ and Fe 2+ substantially inhibited the BPA degradation. Natural mediator acetosyringone showed optimum enhancement on BPA degradation. Greater than 90% of the estrogenic activity of BPA was removed by T. versicolor and its laccase. Compared to in vitro degradation with laccase, this study shows that the process of simultaneous laccase production and BPA degradation with T. versicolor was more advantageous since BPA can enhance the laccase production, mediators were unnecessary, degradation rate was not affected by metal ions, and the applicable pH range was broader. This study concludes that T. versicolor and laccase have great potential to treat industrial wastewater containing BPA.

Simultaneous Force Regression and Movement Classification of Fingers via Surface EMG within a Unified Bayesian Framework.

PubMed

Baldacchino, Tara; Jacobs, William R; Anderson, Sean R; Worden, Keith; Rowson, Jennifer

2018-01-01

This contribution presents a novel methodology for myolectric-based control using surface electromyographic (sEMG) signals recorded during finger movements. A multivariate Bayesian mixture of experts (MoE) model is introduced which provides a powerful method for modeling force regression at the fingertips, while also performing finger movement classification as a by-product of the modeling algorithm. Bayesian inference of the model allows uncertainties to be naturally incorporated into the model structure. This method is tested using data from the publicly released NinaPro database which consists of sEMG recordings for 6 degree-of-freedom force activations for 40 intact subjects. The results demonstrate that the MoE model achieves similar performance compared to the benchmark set by the authors of NinaPro for finger force regression. Additionally, inherent to the Bayesian framework is the inclusion of uncertainty in the model parameters, naturally providing confidence bounds on the force regression predictions. Furthermore, the integrated clustering step allows a detailed investigation into classification of the finger movements, without incurring any extra computational effort. Subsequently, a systematic approach to assessing the importance of the number of electrodes needed for accurate control is performed via sensitivity analysis techniques. A slight degradation in regression performance is observed for a reduced number of electrodes, while classification performance is unaffected.

Development and validation of an HPLC method for tetracycline-related USP monographs.

PubMed

Hussien, Emad M

2014-09-01

A novel reversed-phase HPLC method was developed and validated for the assay of tetracycline hydrochloride and the limit of 4-epianhydrotetracycline hydrochloride impurity in tetracycline hydrochloride commercial bulk and pharmaceutical products. The method employed L1 (3 µm, 150 × 4.6 mm) columns, a mobile phase of 0.1% phosphoric acid and acetonitrile at a flow rate of 1.0 mL/min, and detection at 280 nm. The separation was performed in HPLC gradient mode. Forced degradation studies showed that tetracycline eluted as a spectrally pure peak and was well resolved from its degradation products. The fast degradation of tetracycline hydrochloride and 4-epianhydrotetracycline hydrochloride in solution was retarded by controlling the autosampler temperature at 4 °C and using 0.1% H3 PO4 as diluent. The robustness of the method was tested starting with the maximum variations allowed in the US Pharmacopeia (USP) general chapter Chromatography <621>. The method was linear over the range 80-120% of the assay concentration (0.1 mg/mL) for tetracycline hydrochloride and 50-150% of the acceptance criteria specified in the individual USP monographs for 4-epianhydrotetracycline hydrochloride. The limit of quantification for 4-epianhydrotetracycline hydrochloride was 0.1 µg/mL, 20 times lower than the acceptance criteria. The method was specific, precise, accurate and robust. Copyright © 2014 John Wiley & Sons, Ltd.

[Microbial degradation of 3-phenoxybenzoic acid--A review].

PubMed

Deng, Weiqin; Liu, Shuliang; Yao, Kai

2015-09-04

3-phenoxybenzoic acid (3-PBA) with estrogen toxicity is one of the intermediate products of most pyrethroid pesticides. 3-PBA is difficult to degrade in the natural environment, and threatens food safety and human health. Microbial degradation of pyrethroids and their intermediate product (3-PBA) has become a hot topic in recent years. Here, we reviewed microbial species, degrading enzymes and degradation genes, degradation pathways of 3-PBA degrading and the application of 3-PBA degradation strains. This article provides references for the study of 3-PBA degradation by microorganisms.

High Modulus Biodegradable Polyurethanes for Vascular Stents: Evaluation of Accelerated in vitro Degradation and Cell Viability of Degradation Products

PubMed Central

Sgarioto, Melissa; Adhikari, Raju; Gunatillake, Pathiraja A.; Moore, Tim; Patterson, John; Nagel, Marie-Danielle; Malherbe, François

2015-01-01

We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed viability of about 40% for HUVEC cells. However, the viability was over 80% when the solution was diluted to 50% and below. The growth of HUVEC cells is similar to but not identical to that observed with tissue culture polystyrene standard (TCPS). The results from this in vitro study suggested that the PUs in the series degraded primarily due to the SS degradation and the cell viability of the accumulated acidic degradation products showed poor viability to HUVEC cells when tested undiluted, however particles released to the degradation medium showed cell viability over 80%. PMID:26000274

Voice emotion perception and production in cochlear implant users.

PubMed

Jiam, N T; Caldwell, M; Deroche, M L; Chatterjee, M; Limb, C J

2017-09-01

Voice emotion is a fundamental component of human social interaction and social development. Unfortunately, cochlear implant users are often forced to interface with highly degraded prosodic cues as a result of device constraints in extraction, processing, and transmission. As such, individuals with cochlear implants frequently demonstrate significant difficulty in recognizing voice emotions in comparison to their normal hearing counterparts. Cochlear implant-mediated perception and production of voice emotion is an important but relatively understudied area of research. However, a rich understanding of the voice emotion auditory processing offers opportunities to improve upon CI biomedical design and to develop training programs benefiting CI performance. In this review, we will address the issues, current literature, and future directions for improved voice emotion processing in cochlear implant users. Copyright © 2017 Elsevier B.V. All rights reserved.

Bacterial production and their role in the removal of dissolved organic matter from tributaries of drinking water reservoirs.

PubMed

Kamjunke, Norbert; Oosterwoud, Marieke R; Herzsprung, Peter; Tittel, Jörg

2016-04-01

Enhanced concentrations of dissolved organic matter (DOM) in freshwaters are an increasing problem in drinking water reservoirs. In this study we investigated bacterial DOM degradation rates in the tributaries of the reservoirs and tested the hypotheses that (1) DOM degradation is high enough to decrease DOM loads to reservoirs considerably, (2) DOM degradation is affected by stream hydrology, and (3) phosphorus addition may stimulate bacterial DOM degradation. Bacterial biomass production, which was used as a measure of DOM degradation, was highest in summer, and was usually lower at upstream than at downstream sites. An important proportion of bacterial production was realized in epilithic biofilms. Production of planktonic and biofilm bacteria was related to water temperature. Planktonic production weakly correlated to DOM quality and to total phosphorus concentration. Addition of soluble reactive phosphorus did not stimulate bacterial DOM degradation. Overall, DOM was considerably degraded in summer at low discharge levels, whereas degradation was negligible during flood events (when DOM load in reservoirs was high). The ratio of DOM degradation to total DOM release was negatively related to discharge. On annual average, only 0.6-12% of total DOM released by the catchments was degraded within the tributaries. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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.

Quantifying pretreatment degradation compounds in solution and accumulated by cells during solids and yeast recycling in the Rapid Bioconversion with Integrated recycling Technology process using AFEX™ corn stover.

PubMed

Sarks, Cory; Higbee, Alan; Piotrowski, Jeff; Xue, Saisi; Coon, Joshua J; Sato, Trey K; Jin, Mingjie; Balan, Venkatesh; Dale, Bruce E

2016-04-01

Effects of degradation products (low molecular weight compounds produced during pretreatment) on the microbes used in the RaBIT (Rapid Bioconversion with Integrated recycling Technology) process that reduces enzyme usage up to 40% by efficient enzyme recycling were studied. Chemical genomic profiling was performed, showing no yeast response differences in hydrolysates produced during RaBIT enzymatic hydrolysis. Concentrations of degradation products in solution were quantified after different enzymatic hydrolysis cycles and fermentation cycles. Intracellular degradation product concentrations were also measured following fermentation. Degradation product concentrations in hydrolysate did not change between RaBIT enzymatic hydrolysis cycles; the cell population retained its ability to oxidize/reduce (detoxify) aldehydes over five RaBIT fermentation cycles; and degradation products accumulated within or on the cells as RaBIT fermentation cycles increased. Synthetic hydrolysate was used to confirm that pretreatment degradation products are the sole cause of decreased xylose consumption during RaBIT fermentations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lead Exposure in the Special Operations Shooter How to Prevent Cognitive Decline and Permanent Disability.

PubMed

Brandon, Jonathan W; Solarczyk, Justin K; Durrani, Timur S

Lead toxicity is an important environmental disease and its effects on the human body can be devastating. Unique exposures to Special Operations Forces personnel may include use of firing ranges, use of automotive fuels, production of ammunition, and bodily retention of bullets. Toxicity may degrade physical and psychological fitness, and cause long-term negative health outcomes. Specific effects on fine motor movements, reaction times, and global function could negatively affect shooting skills and decision-making. Biologic monitoring and chelation treatment are poor solutions for protecting this population. Through primary prevention, Special Operations Forces personnel can be protected, in any environment, from the devastating effects of lead exposure. This article offers tools to physicians, environmental service officers, and Special Operations Medics for primary prevention of lead poisoning in the conventional and the austere or forward deployed environments. 2018.

Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach

NASA Astrophysics Data System (ADS)

Draebing, D.; Krautblatter, M.; Dikau, R.

2014-12-01

Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

DETERMINATION OF INTERFERING TRIAZINE DEGRADATION PRODUCTS BY GAS CHROMATOGRAPHY-ION TRAP MASS SPECTROMETRY

EPA Science Inventory

Deethyl atrazine (DEA), along with other triazine degradation products, has been added to the US Environmental Protection Agency's Drinking Water Contaminant Candidate List (CCL). In its gas chromatographic (GC) analysis, deethyl atrazine, a degradation product of atrazine, can ...

Environmental technologies of woody crop production systems

USDA-ARS?s Scientific Manuscript database

Land degradation is a threat to global sustainability with an estimated 25% of the world’s land area already degraded. Soil erosion, loss of productivity potential, biodiversity loss, water shortage, and soil pollution are ongoing processes that decrease or degrade ecosystem services. Degradation ra...

Validated stability-indicating spectrophotometric methods for the determination of cefixime trihydrate in the presence of its acid and alkali degradation products.

PubMed

Mostafa, Nadia M; Abdel-Fattah, Laila; Weshahy, Soheir A; Hassan, Nagiba Y; Boltia, Shereen A

2015-01-01

Five simple, accurate, precise, and economical spectrophotometric methods have been developed for the determination of cefixime trihydrate (CFX) in the presence of its acid and alkali degradation products without prior separation. In the first method, second derivative (2D) and first derivative (1D) spectrophotometry was applied to the absorption spectra of CFX and its acid (2D) or alkali (1D) degradation products by measuring the amplitude at 289 and 308 nm, respectively. The second method was a first derivative (1DD) ratio spectrophotometric method where the peak amplitudes were measured at 311 nm in presence of the acid degradation product, and 273 and 306 nm in presence of its alkali degradation product. The third method was ratio subtraction spectrophotometry where the drug is determined at 286 nm in laboratory-prepared mixtures of CFX and its acid or alkali degradation product. The fourth method was based on dual wavelength analysis; two wavelengths were selected at which the absorbances of one component were the same, so wavelengths 209 and 252 nm were used to determine CFX in presence of its acid degradation product and 310 and 321 nm in presence of its alkali degradation product. The fifth method was bivariate spectrophotometric calibration based on four linear regression equations obtained at the wavelengths 231 and 290 nm, and 231 and 285 nm for the binary mixture of CFX with either its acid or alkali degradation product, respectively. The developed methods were successfully applied to the analysis of CFX in laboratory-prepared mixtures and pharmaceutical formulations with good recoveries, and their validation was carried out following the International Conference on Harmonization guidelines. The results obtained were statistically compared with each other and showed no significant difference with respect to accuracy and precision.

On-Line Ion Exchange Liquid Chromatography as a Process Analytical Technology for Monoclonal Antibody Characterization in Continuous Bioprocessing.

PubMed

Patel, Bhumit A; Pinto, Nuno D S; Gospodarek, Adrian; Kilgore, Bruce; Goswami, Kudrat; Napoli, William N; Desai, Jayesh; Heo, Jun H; Panzera, Dominick; Pollard, David; Richardson, Daisy; Brower, Mark; Richardson, Douglas D

2017-11-07

Combining process analytical technology (PAT) with continuous production provides a powerful tool to observe and control monoclonal antibody (mAb) fermentation and purification processes. This work demonstrates on-line liquid chromatography (on-line LC) as a PAT tool for monitoring a continuous biologics process and forced degradation studies. Specifically, this work focused on ion exchange chromatography (IEX), which is a critical separation technique to detect charge variants. Product-related impurities, including charge variants, that impact function are classified as critical quality attributes (CQAs). First, we confirmed no significant differences were observed in the charge heterogeneity profile of a mAb through both at-line and on-line sampling and that the on-line method has the ability to rapidly detect changes in protein quality over time. The robustness and versatility of the PAT methods were tested by sampling from two purification locations in a continuous mAb process. The PAT IEX methods used with on-line LC were a weak cation exchange (WCX) separation and a newly developed shorter strong cation exchange (SCX) assay. Both methods provided similar results with the distribution of percent acidic, main, and basic species remaining unchanged over a 2 week period. Second, a forced degradation study showed an increase in acidic species and a decrease in basic species when sampled on-line over 7 days. These applications further strengthen the use of on-line LC to monitor CQAs of a mAb continuously with various PAT IEX analytical methods. Implementation of on-line IEX will enable faster decision making during process development and could potentially be applied to control in biomanufacturing.

Tactics, Techniques, and Procedures (TTP) for Migrant Camp Operations

DTIC Science & Technology

1995-04-15

interchangeable and, therefore, usually do not degrade a combat unit if tasked to deploy independently. Also, the Air Force frequently tasks composite...Prime BEEF teams from multiple bases rather than degrade a combat unit’s capabilities. (2) Horizontal construction capabilities, usually airfield or...special understanding and sympathy. They should receive all necessary assistance, and they should not be subject to cruel , inhumane, or degrading

Effects of Oil-Contaminated Sediments on Submerged Vegetation: An Experimental Assessment of Ruppia maritima.

PubMed

Martin, Charles W; Hollis, Lauris O; Turner, R Eugene

2015-01-01

Oil spills threaten the productivity of ecosystems through the degradation of coastal flora and the ecosystem services these plants provide. While lab and field investigations have quantified the response of numerous species of emergent vegetation to oil, the effects on submerged vegetation remain uncertain. Here, we discuss the implications of oil exposure for Ruppia maritima, one of the most common species of submerged vegetation found in the region affected by the recent Deepwater Horizon oil spill. We grew R. maritima in a range of manipulated sediment oil concentrations: 0, 0.26, 0.53, and 1.05 mL oil /L tank volume, and tracked changes in growth (wet weight and shoot density/length), reproductive activity (inflorescence and seed production), root characteristics (mass, length, diameter, and area), and uprooting force of plants. While no statistical differences were detected in growth, plants exhibited significant changes to reproductive output, root morphology, and uprooting force. We found significant reductions in inflorescences and fruiting bodies at higher oil concentrations. In addition, the roots growing in the high oil were shorter and wider. Plants in medium and high oil required less force to uproot. A second experiment was performed to separate the effects of root morphology and oiled sediment properties and indicated that there were also changes to sediment cohesion that contributed to a reduction in uprooting forces in medium and high oil. Given the importance of sexual reproduction for these plants, oil contamination may have substantial population-level effects. Moreover, areas containing buried oil may be more susceptible to high energy storm events due to the reduction in uprooting force of foundation species such as R. maritima.

Effects of Oil-Contaminated Sediments on Submerged Vegetation: An Experimental Assessment of Ruppia maritima

PubMed Central

Martin, Charles W.; Hollis, Lauris O.; Turner, R. Eugene

2015-01-01

Oil spills threaten the productivity of ecosystems through the degradation of coastal flora and the ecosystem services these plants provide. While lab and field investigations have quantified the response of numerous species of emergent vegetation to oil, the effects on submerged vegetation remain uncertain. Here, we discuss the implications of oil exposure for Ruppia maritima, one of the most common species of submerged vegetation found in the region affected by the recent Deepwater Horizon oil spill. We grew R. maritima in a range of manipulated sediment oil concentrations: 0, 0.26, 0.53, and 1.05 mL oil /L tank volume, and tracked changes in growth (wet weight and shoot density/length), reproductive activity (inflorescence and seed production), root characteristics (mass, length, diameter, and area), and uprooting force of plants. While no statistical differences were detected in growth, plants exhibited significant changes to reproductive output, root morphology, and uprooting force. We found significant reductions in inflorescences and fruiting bodies at higher oil concentrations. In addition, the roots growing in the high oil were shorter and wider. Plants in medium and high oil required less force to uproot. A second experiment was performed to separate the effects of root morphology and oiled sediment properties and indicated that there were also changes to sediment cohesion that contributed to a reduction in uprooting forces in medium and high oil. Given the importance of sexual reproduction for these plants, oil contamination may have substantial population-level effects. Moreover, areas containing buried oil may be more susceptible to high energy storm events due to the reduction in uprooting force of foundation species such as R. maritima. PMID:26430971

Design of Ag/ and Pt/TiO2-SiO2 nanomaterials for the photocatalytic degradation of phenol under solar irradiation.

PubMed

Matos, Juan; Llano, Biviana; Montaña, Ricmary; Poon, Po S; Hidalgo, Maria C

2018-05-01

The design of hybrid mesoporous TiO 2 -SiO 2 (TS1) materials decorated with Ag and Pt nanoparticles was performed. The photocatalytic degradation of phenol under artificial solar irradiation was studied and the activity and selectivity of the intermediate products were verified. TiO 2 -SiO 2 was prepared by sol-gel method while Ag- and Pt-based photocatalysts (TS1-Ag and TS1-Pt) were prepared by photodeposition of the noble metals on TS1. Two series of photocatalysts were prepared varying Ag and Pt contents (0.5 and 1.0 wt%). An increase in the photocatalytic activity up to two and five times higher than TS1 was found on TS1-Ag-1.0 and TS1-Pt-1.0, respectively. Changes in the intermediate products were detected on Ag- and Pt-based photocatalysts with an increase in the catechol formation up to 3.3 and 6.6 times higher than that observed on TS1, respectively. A two-parallel reaction mechanism for the hydroquinone and catechol formation is proposed. A linear correlation between the photocatalytic activity and the surface concentration of noble metals was found indicating that the electron affinity of noble metals is the driven force for both the increase in the photoactivity and for the remarkable changes in the selectivity of products.

Solid state compatibility study and characterization of a novel degradation product of tacrolimus in formulation.

PubMed

Rozman Peterka, Tanja; Grahek, Rok; Hren, Jure; Bastarda, Andrej; Bergles, Jure; Urleb, Uroš

2015-06-10

Tacrolimus is macrolide drug that is widely used as a potent immunosuppressant. In the present work compatibility testing was conducted on physical mixtures of tacrolimus with excipients and on compatibility mixtures prepared by the simulation of manufacturing process used for the final drug product preparation. Increase in one major degradation product was detected in the presence of magnesium stearate based upon UHPLC analysis. The degradation product was isolated by preparative HPLC and its structure was elucidated by NMR and MS studies. Mechanism of the formation of this degradation product is proposed based on complementary degradation studies in a solution and structural elucidation data. The structure was proven to be alpha-hydroxy acid which is formed from the parent tacrolimus molecule through a benzilic acid type rearrangement reaction in the presence of divalent metallic cations. Degradation is facilitated at higher pH values. Copyright © 2015 Elsevier B.V. All rights reserved.

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

EPA Science Inventory

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...

WEATHERING DEGRADATION OF A POLYURETHANE COATING. (R828081E01)

EPA Science Inventory

The degradation of polyurethane topcoat over a chromate pigmented epoxy primer was examined by atomic force microscopy (AFM), scanning electronic microscopy (SEM), X-ray photo-electron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR) after the coated pane...

Anthracycline antibiotics derivate mitoxantrone-Destructive sorption and photocatalytic degradation.

PubMed

Štenglová-Netíková, Irena R; Petruželka, Luboš; Šťastný, Martin; Štengl, Václav

2018-01-01

Nanostructured titanium(IV) oxide was used for the destructive adsorption and photocatalytic degradation of mitoxantrone (MTX), a cytostatic drug from the group of anthracycline antibiotics. During adsorption on a titania dioxide surface, four degradation products of MTX, mitoxantrone dicarboxylic acid, 1,4-dihydroxy-5-((2-((2-hydroxyethyl)amino)ethyl)amino)-8-((2-(methylamino)ethyl)amino)anthracene-9,10-dione, 1,4-dihydroxy-5,8-diiminoanthracene-9,10(5H,8H)-dione and 1,4-dihydroxy-5-imino-8-(methyleneamino)anthracene-9,10(5H,8H)-dione, were identified. In the case of photocatalytic degradation, only one degradation product after 15 min at m/z 472 was identified. This degradation product corresponded to mitoxantrone dicarboxylic acid, and complete mineralization was attained in one hour. Destructive adsorbent manganese(IV) oxide, MnO2, was used only for the destructive adsorption of MTX. Destructive adsorption occurred only for one degradation product, mitoxantrone dicarboxylic acid, against anatase TiO2.

The Fungal Degradation of Wood and Wood Products Selected Bibliography

DTIC Science & Technology

1981-08-01

Pi 0-Alt^Jihi 1 TECHNICAL LIBRARY SPECIAL PUBLICATION ARLCD-SP-81006 THE FUNGAL DEGRADATION OF WOOD AND WOOD PRODUCTS SELECTED BIBLIOGRAPHY...GOVT ACCESSION NO. READ INSTRUCTIONS BEFORE COMPLETING FORM 3. RECIPIENT’S CATALOG NUMBER 4. TITLE fand SubJltJo; THE FUNGAL DEGRADATION OF...search con- centrated on the microbiological deterioration or degradation of wood (trees) or wood products which are found or used in tropical

Activity of meadowfoam (Limnanthes alba) seed meal glucolimnanthin degradation products against soilborne pathogens.

PubMed

Zasada, Inga A; Weiland, Jerry E; Reed, Ralph L; Stevens, Jan F

2012-01-11

Meadowfoam (Limnanthes alba L.) is a herbaceous winter-spring annual grown as a commercial oilseed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products, and therefore the meal may have potential in the management of soilborne pathogens. To maximize the pest-suppressive potential of meadowfoam seed meal, it would be beneficial to know the toxicity of individual glucolimnanthin degradation products against specific soilborne pathogens. Meloidogyne hapla second-stage juveniles (J2) and Pythium irregulare and Verticillium dahliae mycelial cultures were exposed to glucolimnanthin as well as its degradation products. Glucolimnanthin and its degradation product, 2-(3-methoxyphenyl)acetamide, were not toxic to any of the soilborne pathogens at concentrations up to 1.0 mg/mL. Two other degradation products, 2-(3-methoxymethyl)ethanethioamide and 3-methoxyphenylacetonitrile, were toxic to M. hapla and P. irregulare but not V. dahliae. The predominant enzyme degradation product, 3-methoxybenzyl isothiocyanate, was the most toxic compound against all of the soilborne pathogens, with M. hapla being the most sensitive with EC(50) values (0.0025 ± 0.0001 to 0.0027 ± 0.0001 mg/mL) 20-40 times lower than estimated EC(50) mortality values generated for P. irregulare and V. dahliae (0.05 and 0.1 mg/mL, respectively). The potential exists to manipulate meadowfoam seed meal to promote the production of specific degradation products. The conversion of glucolimnanthin into its corresponding isothiocyanate should optimize the biopesticidal properties of meadowfoam seed meal against M. hapla, P. irregulare, and V. dahliae.

Degradation of lindane by a novel embedded bio-nano hybrid system in aqueous environment.

PubMed

Salam, Jaseetha Abdul; Das, Nilanjana

2015-03-01

The objective of this study was to evaluate the effect of an embedded bio-nano hybrid system using nanoscale zinc oxide (n-ZnO) and lindane-degrading yeast Candida VITJzN04 for lindane degradation. Nano-embedding of the yeast was done with chemically synthesized n-ZnO particles (50 mg/mL) and was visualized by atomic force microscope (AFM) and scanning electron microscope (SEM). Nanoparticles were embedded substantially on the surfaces of the yeast cells and translocated into the cell cytoplasm without causing any lethal effect to the cell until 50 mg/mL. Lindane (600 mg/L) degradation was studied both in the individual and hybrid system. Rapid reductive-dechlorination of lindane was attained with n-ZnO under illuminated conditions, with the generation of chlorobenzene and benzene as dechlorination products. The bio-nano hybrid was found to be more effective compared to the native yeasts for lindane degradation and resulted in complete removal within 3 days. The kinetic data analysis implied that the half-life of lindane was 9 h for bio-nano hybrid and 28 h for Candida VITJzN04. The enhanced lindane degradation by bio-nano hybrid might be due to increased porosity and permeability of the yeast cell membrane, facilitating the easy entry of lindane into cell cytoplasm and n-ZnO-mediated dechlorination. To the best of our knowledge, this report, for the first time, suggests the use of n-ZnO-mediated dechlorination of lindane and the novel bio-nano hybrid system that reduces the half-life to one third of the time taken by the yeast alone. The embedded bio-nano hybrid system may be exploited as an effective remediation tool for the treatment of lindane-contaminated wastewaters.

The bioactivity of dietary anthocyanins is likely to be mediated by their degradation products.

PubMed

Kay, Colin D; Kroon, Paul A; Cassidy, Aedin

2009-05-01

To date the in vitro mechanistic bioactivity of anthocyanins has been exclusively explored using aglycones and glycoside conjugates, despite a lack of evidence establishing these as the biologically available forms. We conducted intestinal epithelial cell (Caco-2 cells) culture experiments, which indicated that after a 4 h incubation of anthocyanins in cell-free culture media (DMEM), 57% of the initial cyanidin-3-glucoside (C3G) and 96% of cyanidin had degraded. The level of degradation was not statistically different from that of cultured cell incubations, suggesting that degradation was spontaneous. Degradation products were identified as protocatechuic acid (PCA) and phloroglucinaldehyde (PGA), and were confirmed in two other buffer matrices (phosphate and Hank's buffers). In cultured cell media the degradation products PCA and PGA were metabolised to glucuronide and sulphate conjugates, as indicated by both enzyme hydrolysis (sulphatase and glucuronidase treatments) and MS (PCA and PGA m/z = 155; sulphate = 235; glucuronide = 331). These data suggest a significant proportion of intestinal metabolites of anthocyanins are likely to be conjugates of their degradation products. Future efforts to establish the biological activities of anthocyanins should therefore include the investigation of phenolic acid and aldehyde products of degradation, along with their respective metabolites.

Computational aspects of real-time simulation of rotary-wing aircraft. M.S. Thesis

NASA Technical Reports Server (NTRS)

Houck, J. A.

1976-01-01

A study was conducted to determine the effects of degrading a rotating blade element rotor mathematical model suitable for real-time simulation of rotorcraft. Three methods of degradation were studied, reduction of number of blades, reduction of number of blade segments, and increasing the integration interval, which has the corresponding effect of increasing blade azimuthal advance angle. The three degradation methods were studied through static trim comparisons, total rotor force and moment comparisons, single blade force and moment comparisons over one complete revolution, and total vehicle dynamic response comparisons. Recommendations are made concerning model degradation which should serve as a guide for future users of this mathematical model, and in general, they are in order of minimum impact on model validity: (1) reduction of number of blade segments; (2) reduction of number of blades; and (3) increase of integration interval and azimuthal advance angle. Extreme limits are specified beyond which a different rotor mathematical model should be used.

Wood products : thermal degradation and fire

Treesearch

R.H. White; M.A. Dietenberger

2001-01-01

Wood is a thermally degradable and combustible material. Applications range from a biomass providing useful energy to a building material with unique properties. Wood products can contribute to unwanted fires and be destroyed as well. Minor amounts of thermal degradation adversely affect structural properties. Therefore, knowledge of the thermal degradation and fire...

Methanogenesis acceleration of fresh landfilled waste by micro-aeration.

PubMed

Shao, Li-Ming; He, Pin-Jing; Zhang, Hua; Yu, Xiao-Hua; Li, Guo-Jian

2005-01-01

When municipal solid waste (MSW) with high content of food waste is landfilled, the rapid hydrolysis of food waste results in the imbalance of anaerobic metabolism in the landfill layer, indicated by accumulation of volatile fatty acids (VFA) and decrease of pH value. This occurrence could lead to long lag time before the initiation of methanogenesis and to the production of strong leachate. Simulated landfill columns with forced aeration, with natural ventilation, and with no aeration, were monitored regarding their organics degradation rate with leachate recirculation. Hydrolysis reactions produced strong leachate in the column with no aeration. With forced aeration, the produced VFA could be effectively degraded, leading to the reduction in COD of the leachate effluent since the week 3. The CH4 in the landfill gas from the column with aeration rate of 0.39 m3/(m3 x d) and frequency of twice/d, leachate recirculation rate of 12.2 mm/d and frequency of twice/d, could amount to 40% (v/v) after only 20 weeks. This amount had increased up to 50% afterward even with no aeration. Most of COD in the recirculated leachate was removed. Using natural ventilation, CH4 could also be produced and the COD of the leachate effluent be reduced after 10 weeks of operation. However, the persistent existence of oxygen in the landfill layer yielded instability in methanogenesis process.

Stability of peatland carbon to rising temperatures

DOE PAGES

Wilson, R. M.; Hopple, A. M.; Tfaily, M. M.; ...

2016-12-13

Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. Here, we show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH 4 emissions. But, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20–30 cm of peat from experimental plots have higher CH 4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH 4 and COmore » 2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. Furthermore, there are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. Our results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.« less

Stability of peatland carbon to rising temperatures

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

Wilson, R. M.; Hopple, A. M.; Tfaily, M. M.

Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. Here, we show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH 4 emissions. But, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20–30 cm of peat from experimental plots have higher CH 4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH 4 and COmore » 2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. Furthermore, there are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. Our results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.« less

Degradation of a lyophilized formulation of BMS-204352: identification of degradants and role of elastomeric closures.

PubMed

Nassar, Munir N; Nesarikar, Vishwas V; Lozano, Ruben; Huang, Yande; Palaniswamy, Venkatapuram

2005-01-01

The purpose of this study was to identify two degradation products formed in the parenteral lyophilized formulation of BMS-204352, investigate the possible role of elastomeric closures in their formation, and develop a strategy to minimize/control their formation. The first degradant was identified as the hydroxymethyl derivative (formaldehyde adduct, BMS-215842) of the drug substance formed by the reaction of BMS-204352 with formaldehyde. Structure confirmation was based on liquid chromatography/mass spectroscopy (LC/MS), nuclear magnetic resonance (NMR), and chromatographic comparison to an authentic sample of the hydroxymethyl degradation product, BMS-215842. To confirm the hypothesis that formaldehyde originated from the rubber closure, migrated into the product, and reacted with BMS-204352 drug substance to form the hydroxymethyl degradant, lyophilized drug product was manufactured, the vials were stoppered with two different rubber closure formulations, and its stability was monitored. The formaldehyde adduct degradant was observed only in the drug product vials stoppered with one of the rubber closures that was evaluated. Although formaldehyde has not been detected historically as leachable and is not an added ingredient in the rubber formulation, information obtained from the stopper manufacturer indicated that the reinforcing agent used in the stopper formulation may be a potential source of formaldehyde. The second degradant was identified as the desfluoro hydroxy analog (BMS-188929) based on LC/MS, NMR, and chromatographic comparison to an authentic sample of the desfluoro hydroxy degradation product.

Sensorimotor adaptation to inertial forces in a multi-force environment does not depend on the number of targets: indirect validation of the altered-proprioception hypothesis.

PubMed

Bourdin, C; Bock, O

2006-11-20

The ability of our sensorimotor system to adapt to changing and complex environmental demands has been under experimental scrutiny for more than a century. Previous works have shown that aimed arm movements adapt quickly and completely to Coriolis force, but incompletely to the combination of Coriolis and centrifugal forces without visual cues. Two hypotheses may be advanced to explain this discrepancy: the workspace-exploration hypothesis, and the degraded-proprioception hypothesis. The aim of this study was to distinguish between the above two alternatives by comparing adaptive improvement during off-axis rotation in subjects pointing at one, three or seven different targets in complete darkness. Two main results emerge: (a) off-axis rotation led initially to errors in the direction of Coriolis force and in the opposite direction of the centrifugal force; (b) the size of the visited workspace has no effect on the way the subjects adapt to a multi-force environment. The lack of a target-number effect and the persistence of lateral errors in the pointing movements performed during rotation of the platform, support the degraded-proprioception rather than the workspace-exploration hypothesis of adaptation to a multi-force environment.

Activity of Meadowfoam (Limnanthes alba) Seed Meal Glucolimnanthin Degradation Products against Soil-Borne Pathogens

PubMed Central

ZASADA, INGA A; WEILAND, JERRY E; REED, RALPH L; STEVENS, JAN F

2014-01-01

Meadowfoam (Limnanthes alba L.) is a herbaceous winter-spring annual grown as a commercial oil seed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate, glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products and therefore the meal may have potential in the management of soil-borne pathogens. To maximize the pest suppressive potential of meadowfoam seed meal, it would be beneficial to know the toxicity of individual glucolimnanthin degradation products against specific soil-borne pathogens. Meloidogyne hapla second-stage juveniles (J2) and Pythium irregulare and Verticillium dahliae mycelial cultures were exposed to glucolimnanthin as well as its degradation products. Glucolimnanthin and its degradation product, 2-(3-methoxyphenyl)acetamide, were not toxic to any of the soil-borne pathogens at concentrations up to 1.0 mg/mL. Two other degradation products, 2-(3-methoxymethyl)ethanethioamide and 3-methoxyphenylacetonitrile, were toxic to M. hapla and P. irregulare but not V. dahliae. The predominant enzyme degradation product, 3-methoxybenzyl isothiocyanate was the most toxic compound against all of the soil-borne pathogens with M. hapla being the most sensitive with EC50 values (0.0025 ± 0.0001 to 0.0027 ± 0.0001 mg/mL) 20 to 40 times lower than estimated EC50 mortality values generated for P. irregulare and V. dahliae (0.05 and 0.1 mg/mL, respectively). The potential exists to manipulate meadowfoam seed meal to promote the production of specific degradation products. The conversion of glucolimnanthin into its corresponding isothiocyanate should optimize the biopesticidal properties of meadowfoam seed meal against M. hapla, P. irregulare, and V. dahliae. PMID:22142246

Selective determination of ertapenem in the presence of its degradation product

NASA Astrophysics Data System (ADS)

Hassan, Nagiba Y.; Abdel-Moety, Ezzat M.; Elragehy, Nariman A.; Rezk, Mamdouh R.

2009-06-01

Stability-indicative determination of ertapenem (ERTM) in the presence of its β-lactam open-ring degradation product, which is also the metabolite, is investigated. The degradation product has been isolated, via acid-degradation, characterized and elucidated. Selective quantification of ERTM, singly in bulk form, pharmaceutical formulations and/or in the presence of its major degradant is demonstrated. The indication of stability has been undertaken under conditions likely to be expected at normal storage conditions. Among the spectrophotometric methods adopted for quantification are first derivative ( 1D), first derivative of ratio spectra ( 1DD) and bivariate analysis.

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

NASA Astrophysics Data System (ADS)

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).

Structure elucidation and degradation kinetic study of Ofloxacin using surface enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

El-Zahry, Marwa R.; Lendl, Bernhard

2018-03-01

A simple, fast and sensitive surface enhanced Raman spectroscopy (SERS) method for quantitative determination of fluoroquinolone antibiotic Ofloxacin (OFX) is presented. Also the stability behavior of OFX was investigated by monitoring the SERS spectra of OFX after various degradation processes. Acidic, basic and oxidative force degradation processes were applied at different time intervals. The forced degradation conditions were conducted and followed using SERS method utilizing silver nanoparticles (Ag NPs) as a SERS substrate. The Ag NPs colloids were prepared by reduction of silver nitrate using polyethyelene glycol (PEG) as a reducing and stabilizing agent. Validation tests were done in accordance with International Conference on Harmonization (ICH) guidelines. The calibration curve with a correlation coefficient (R = 0.9992) was constructed as a relationship between the concentration range of OFX (100-500 ng/ml) and SERS intensity at 1394 cm- 1 band. LOD and LOQ values were calculated and found to be 23.5 ng/ml and 72.6 ng/ml, respectively. The developed method was applied successfully for quantitation of OFX in different pharmaceutical dosage forms. Kinetic parameters were calculated including rate constant of the degradation of the studied antibiotic.

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

PubMed

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.

A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog.

PubMed

Dunphy, Michael J; Sysel, Annette M; Lupica, Joseph A; Griffith, Kristie; Sherrod, Taylor; Bauer, Joseph A

2014-04-01

Nitrosylcobalamin (NO-Cbl), a novel vitamin B 12 analog and anti-tumor agent, functions as a biologic 'Trojan horse', utilizing the vitamin B 12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis ® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min -1 ) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B 12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl.

A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog

PubMed Central

Dunphy, Michael J.; Sysel, Annette M.; Lupica, Joseph A.; Griffith, Kristie; Sherrod, Taylor

2014-01-01

Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min−1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

Degradation of Biofumigant Isothiocyanates and Allyl Glucosinolate in Soil and Their Effects on the Microbial Community Composition

PubMed Central

Hanschen, Franziska S.; Yim, Bunlong; Winkelmann, Traud; Smalla, Kornelia; Schreiner, Monika

2015-01-01

Brassicales species rich in glucosinolates are used for biofumigation, a process based on releasing enzymatically toxic isothiocyanates into the soil. These hydrolysis products are volatile and often reactive compounds. Moreover, glucosinolates can be degraded also without the presence of the hydrolytic enzyme myrosinase which might contribute to bioactive effects. Thus, in the present study the stability of Brassicaceae plant-derived and pure glucosinolates hydrolysis products was studied using three different soils (model biofumigation). In addition, the degradation of pure 2-propenyl glucosinolate was investigated with special regard to the formation of volatile breakdown products. Finally, the influence of pure glucosinolate degradation on the bacterial community composition was evaluated using denaturing gradient gel electrophoresis of 16S rRNA gene amplified from total community DNA. The model biofumigation study revealed that the structure of the hydrolysis products had a significant impact on their stability in the soil but not the soil type. Following the degradation of pure 2-propenyl glucosinolate in the soils, the nitrile as well as the isothiocyanate can be the main degradation products, depending on the soil type. Furthermore, the degradation was shown to be both chemically as well as biologically mediated as autoclaving reduced degradation. The nitrile was the major product of the chemical degradation and its formation increased with iron content of the soil. Additionally, the bacterial community composition was significantly affected by adding pure 2-propenyl glucosinolate, the effect being more pronounced than in treatments with myrosinase added to the glucosinolate. Therefore, glucosinolates can have a greater effect on soil bacterial community composition than their hydrolysis products. PMID:26186695

Degradation of caffeic acid in subcritical water and online HPLC-DPPH assay of degradation products.

PubMed

Khuwijitjaru, Pramote; Suaylam, Boonyanuch; Adachi, Shuji

2014-02-26

Caffeic acid was subjected to degradation under subcritical water conditions within 160-240 °C and at a constant pressure of 5 MPa in a continuous tubular reactor. Caffeic acid degraded quickly at these temperatures; the main products identified by liquid chromatography-diode array detection/mass spectrometry were hydroxytyrosol, protocatechuic aldehyde, and 4-vinylcatechol. The reaction rates for the degradation of caffeic acid and the formation of products were evaluated. Online high-performance liquid chromatography/2,2-diphenyl-1-picryhydrazyl assay was used to determine the antioxidant activity of each product in the solution. It was found that the overall antioxidant activity of the treated solution did not change during the degradation process. This study showed a potential of formation of antioxidants from natural phenolic compounds under these subcritical water conditions, and this may lead to a discovering of novel antioxidants compounds during the extraction by this technique.

Degradation of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking.

PubMed

Siegel, David; Feist, Michael; Proske, Matthias; Koch, Matthias; Nehls, Irene

2010-09-08

The stability of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking was investigated by model experiments using a spiked wholemeal wheat flour matrix. For alternariol and alternariol monomethyl ether, but not for altenuene, degradation products, formed through a sequence of hydrolysis and decarboxylation, could be identified in pilot studies. The simultaneous quantification of alternariol, alternariol monomethyl ether, altenuene, and the degradation products was achieved by a newly developed high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) multimethod. The obtained quantitative data indicate that the Alternaria mycotoxins are barely degraded during wet baking, while significant degradation occurs upon dry baking, with the stability decreasing in the order alternariol monomethyl ether>alternariol>altenuene. The novel degradation products could be detected after the wet baking of flour spiked with alternariol and in a sample survey of 24 commercial cereal based baking products.

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

PubMed

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.

Glycation products in infant formulas: chemical, analytical and physiological aspects.

PubMed

Pischetsrieder, Monika; Henle, Thomas

2012-04-01

Infant formulas are milk-based products, which are adapted to the composition of human milk. To ensure microbiological safety and long shelf life, infant formulas usually undergo rigid heat treatment. As a consequence of the special composition and the heat regimen, infant formulas are more prone to thermally induced degradation reactions than regular milk products. Degradation reactions observed during milk processing comprise lactosylation yielding the Amadori product lactulosyllysine, the formation of advanced glycation end products (AGEs), and protein-free sugar degradation products, as well as protein or lipid oxidation. Several methods have been developed to estimate the heat impact applied during the manufacturing of infant formulas, including indirect methods such as fluorescence analysis as well as the analysis of defined reaction products. Most studies confirm a higher degree of damage in infant formulas compared to regular milk products. Differences between various types of infant formulas, such as liquid, powdered or hypoallergenic formulas depend on the analyzed markers and brands. A considerable portion of protein degradation products in infant formulas can be avoided when process parameters and the quality of the ingredients are carefully controlled. The nutritional consequences of thermal degradation products in infant formulas are largely unknown.

Decreased SAP expression in T cells from patients with SLE contributes to early signaling abnormalities and reduced IL-2 production

PubMed Central

Karampetsou, Maria P.; Comte, Denis; Kis-Toth, Katalin; Terhorst, Cox; Kyttaris, Vasileios C.; Tsokos, George C.

2016-01-01

T cells from patients with systemic lupus erythematosus (SLE) display a number of functions including increased early signaling events following engagement of the T cell receptor (TCR). Signaling lymphocytic activation molecule family (SLAMF) cell surface receptors and the X-chromosome-defined signaling lymphocytic activation molecule-associated protein (SAP) adaptor are important in the development of several immunocyte lineages and modulating immune response. Here we present evidence that SAP protein levels are decreased in T cells and in their main subsets isolated from 32 women and 3 men with SLE independently of disease activity. In SLE T cells the SAP protein is also subject to increased degradation by a caspase-3. Forced expression of SAP in SLE T cells simultaneously heightened IL-2 production, calcium (Ca2+) responses and tyrosine phosphorylation of a number of proteins. Exposure of normal T cells to SLE serum IgG, known to contain anti-CD3/TCR antibodies, resulted in SAP downregulation. We conclude that SLE T cells display reduced levels of the adaptor protein SAP probably as a result of continuous T cell activation and degradation by caspase-3. Restoration of SAP levels in SLE T cells corrects the overexcitable lupus T cell phenotype. PMID:27183584

Degradation of anthracene by laccase of Trametes versicolor in the presence of different mediator compounds.

PubMed

Johannes, C; Majcherczyk, A; Hüttermann, A

1996-10-01

Laccase of Trametes versicolor was generally able to oxidize anthracene in vitro. After 72 h incubation about 35% of the anthracene was transformed stoichiometrically to 9,10-anthraquinone. Transformation of anthracene increased rapidly in the presence of different mediators that readily generate stable radicals: 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1-hydroxybenzotriazole. For the reaction, the presence of both the laccase and the mediator was necessary. In the presence of 0.005 mM 1-hydroxybenzotriazole this conversion had removed 47% of the anthracene after 72 h; 75% of the substrate was oxidized during this period when ABTS (1 mM) was used as mediator. In contrast to reactions without or with only low concentrations of a mediator, there was a discrepancy between the disappearance of anthracene and the formation of 9,10-anthraquinone in mediator-forced reactions. Coupling-products of mediators with anthracene degradation products were found. Anthracene disappeared nearly completely after incubation for 72 h with laccase in a 0.1 mM solution of 1-hydroxybenzotriazole and was transformed to 9,10-anthraquinone in about 80% yield; 90% of the substrate was transformed in the presence of ABTS (2.0 mM) resulting again in 80% quinone. Phenothiazine was not effective in this system.

Decreased SAP Expression in T Cells from Patients with Systemic Lupus Erythematosus Contributes to Early Signaling Abnormalities and Reduced IL-2 Production.

PubMed

Karampetsou, Maria P; Comte, Denis; Kis-Toth, Katalin; Terhorst, Cox; Kyttaris, Vasileios C; Tsokos, George C

2016-06-15

T cells from patients with systemic lupus erythematosus (SLE) display a number of abnormalities, including increased early signaling events following engagement of the TCR. Signaling lymphocytic activation molecule family cell surface receptors and the X-chromosome-defined signaling lymphocytic activation molecule-associated protein (SAP) adaptor are important in the development of several immunocyte lineages and modulating the immune response. We present evidence that SAP protein levels are decreased in T cells and in their main subsets isolated from 32 women and three men with SLE, independent of disease activity. In SLE T cells, SAP protein is also subject to increased degradation by caspase-3. Forced expression of SAP in SLE T cells normalized IL-2 production, calcium (Ca(2+)) responses, and tyrosine phosphorylation of a number of proteins. Exposure of normal T cells to SLE serum IgG, known to contain anti-CD3/TCR Abs, resulted in SAP downregulation. We conclude that SLE T cells display reduced levels of the adaptor protein SAP, probably as a result of continuous T cell activation and degradation by caspase-3. Restoration of SAP levels in SLE T cells corrects the overexcitable lupus T cell phenotype. Copyright © 2016 by The American Association of Immunologists, Inc.

Least-Squares Regression and Spectral Residual Augmented Classical Least-Squares Chemometric Models for Stability-Indicating Analysis of Agomelatine and Its Degradation Products: A Comparative Study.

PubMed

Naguib, Ibrahim A; Abdelrahman, Maha M; El Ghobashy, Mohamed R; Ali, Nesma A

2016-01-01

Two accurate, sensitive, and selective stability-indicating methods are developed and validated for simultaneous quantitative determination of agomelatine (AGM) and its forced degradation products (Deg I and Deg II), whether in pure forms or in pharmaceutical formulations. Partial least-squares regression (PLSR) and spectral residual augmented classical least-squares (SRACLS) are two chemometric models that are being subjected to a comparative study through handling UV spectral data in range (215-350 nm). For proper analysis, a three-factor, four-level experimental design was established, resulting in a training set consisting of 16 mixtures containing different ratios of interfering species. An independent test set consisting of eight mixtures was used to validate the prediction ability of the suggested models. The results presented indicate the ability of mentioned multivariate calibration models to analyze AGM, Deg I, and Deg II with high selectivity and accuracy. The analysis results of the pharmaceutical formulations were statistically compared to the reference HPLC method, with no significant differences observed regarding accuracy and precision. The SRACLS model gives comparable results to the PLSR model; however, it keeps the qualitative spectral information of the classical least-squares algorithm for analyzed components.

Enrofloxacin degradation in broiler chicken manure under various laboratory conditions.

PubMed

Slana, Marko; Sollner-Dolenc, Marija

2016-03-01

The rate of degradation of enrofloxacin in broiler chicken manure has been characterized in the laboratory according to the CVMP guideline on determining the fate of veterinary medicinal products in manure. Degradation was followed in a flow-through system under aerobic and anaerobic conditions, in the dark and in the presence of light. The rate of degradation of enrofloxacin and the formation of its degradation products are dependent on laboratory conditions. A rapid degradation of enrofloxacin in the dark was noticed, where a shorter degradation half-life under aerobic (DT50 = 59.1 days), comparing to anaerobic conditions (DT50 = 88.9 days), was determined. The presence of light slowed down the enrofloxacin degradation half-life, which was significantly shorter under aerobic (DT50 = 115.0 days), comparing to anaerobic conditions (DT50 = 190.8 days). Desethylene-enrofoxacin was the only degradation product formed, its concentrations ranged from 2.5 to 14.9 %. The concentration of the degradation product was approximately 2.5-fold higher under aerobic conditions. Enrofloxacin degradation in sterile manure incubated under sterile conditions was marginal comparing to non-sterile conditions; after 120 days of incubation, approximately 80 % of enrofloxacin was still present in manure and only 1 % of desethylene-enrofloxacin was formed. The present work demonstrates that enrofloxacin degradation in chicken manure is relatively fast when incubated in the dark under aerobic conditions which is the recommended incubation system for chicken manure according to CVMP guideline.

Enhanced Training by a Systemic Governance of Force Capabilities, Tasks, and Processes

DTIC Science & Technology

2013-06-01

18th ICCRTS “C2 in Underdeveloped, Degraded and Denied Operational Environments” Enhanced Training by a Systemic Governance of Force Capabilities...TITLE AND SUBTITLE Enhanced Training by a Systemic Governance of Force Capabilities, Tasks, and Processes 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...assess, evaluate and accredit the Swedish forces. This paper presents a Systemic Governance of Capabilities, Tasks, and Processes applied to the

Spectroscopic study of degradation products of ciprofloxacin, norfloxacin and lomefloxacin formed in ozonated wastewater.

PubMed

Liu, Chen; Nanaboina, Venkateswarlu; Korshin, Gregory V; Jiang, Wenju

2012-10-15

This study addressed the formation and properties of degradation products of ciprofloxacin, norfloxacin and lomefloxacin formed during ozonation of secondary wastewater effluent containing these fluoroquinolone antibiotics. The generation of the degradation products was interpreted in the context of transformations of effluent organic matter (EfOM) tracked via absorbance measurements. The structures of 20 degradation products were elucidated for ciprofloxacin and norfloxacin, respectively. 27 degradation products were identified for lomefloxacin. The prevalent oxidation pathways were suggested based on the structures of the identified products formed in the absence and presence of the hydroxyl radical scavenger t-butanol. These pathways were largely similar for all studied fluoroquinolones and involved attacks on the piperazine ring and the quinolone structure. The quinolone ring remained intact in the presence of t-butanol thus indicating that this functional group could only be oxidized by OH radicals while the piperazine ring was readily oxidized by molecular ozone. The cleavage of the quinolone moiety that resulted in several identified degradation products occurred via the attack by hydroxyl radicals on the carbon-carbon double bond adjacent to the carboxylic acid group. Lomefloxacin had more diverse oxidation products due to the presence of a methyl group on its piperazinyl ring. The concentrations of the identified degradation products behaved non-monotonically as a function of ozone dose or treatment time, yet exhibited interpretable correlations versus changes of EfOM absorbance. Examination of these correlations allowed developing a novel approach for elucidating the transformations of fluoroquinolone antibiotics during ozonation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Forces, energetics, and dynamics of conjugated-carbon ring tethers adhered to CNTs: a computational investigation.

PubMed

Filla, Nicholas; Ramasamy, Ramaraja; Wang, Xianqiao

2018-04-25

The strength and nature of the interactions between carbon nanotubes (CNTs) and molecular tethers plays a vital role in technology such as CNT-enzyme sensors. Tethers that attach noncovalently to CNTs are ideal for retaining the electrical properties of the CNTs since they do not degrade the CNT surface and effect its electrical conductivity. However, leaching due to weak CNT-tether attachment is very common when using noncovalent tethers, and this has limited their use in commercial products including biosensors. Thus, understanding the fundamental mechanics governing the strength of CNT-tether adhesion is crucial for the design of highly sensitive, viable sensors. Here, we computationally investigate the adhesion strength of CNT-tether complexes with 8 different tethering molecules designed to adhere noncovalently to the CNT surface. We study the effects of CNT diameter, CNT chirality, and the size/geometry of the tethering molecule on the adhesion energy and force. Our results show an asymptotic relationship between adhesion strength and CNT diameter. Calculations show that noncovalent tethers tested here can reach adhesion forces and energies that are up to 21% and 54% of the strength of the carbon-carbon single bond force and bond energy respectively. We anticipate our results will help guide CNT-enzyme sensor design to produce sensors with high sensitivity and minimal leaching.

Report: More Information Is Needed On Toxaphene Degradation Products

EPA Pesticide Factsheets

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.

Desertification of forest, range and desert in Tehran province, affected by climate change

NASA Astrophysics Data System (ADS)

Eskandari, Hadi; Borji, Moslem; Khosravi, Hassan; Mesbahzadeh, Tayebeh

2016-06-01

Climate change has been identified as a leading human and environmental crisis of the twenty-first century. Drylands throughout the world have always undergone periods of degradation due to naturally occurring fluctuation in climate. Persistence of widespread degradation in arid and semiarid regions of Iran necessitates monitoring and evaluation. This paper aims to monitor the desertification trend in three types of land use, including range, forest and desert, affected by climate change in Tehran province for the 2000s and 2030s. For assessing climate change at Mehrabad synoptic station, the data of two emission scenarios, including A2 and B2, were used, utilizing statistical downscaling techniques and data generated by the Statistical DownScaling Model (SDSM). The index of net primary production (NPP) resulting from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images was employed as an indicator of destruction from 2001 to 2010. The results showed that temperature is the most significant driving force which alters the net primary production in rangeland, forest and desert land use in Tehran province. On the basis of monitoring findings under real conditions, in the 2000s, over 60 % of rangelands and 80 % of the forest were below the average production in the province. On the other hand, the long-term average changes of NPP in the rangeland and forests indicated the presence of relatively large areas of these land uses with a production rate lower than the desert. The results also showed that, assuming the existence of circumstances of each emission scenarios, the desertification status will not improve significantly in the rangelands and forests of Tehran province.

Forced interaction of cell surface proteins with Derlin-1 in the endoplasmic reticulum is sufficient to induce their dislocation into the cytosol for degradation.

PubMed

Cho, Sunglim; Lee, Miriam; Jun, Youngsoo

2013-01-11

Aberrantly folded proteins in the endoplasmic reticulum (ER) are rapidly removed into the cytosol for degradation by the proteasome via an evolutionarily conserved process termed ER-associated protein degradation (ERAD). ERAD of a subset of proteins requires Derlin-1 for dislocation into the cytosol; however, the molecular function of Derlin-1 remains unclear. Human cytomegalovirus US11 exploits Derlin-1-dependent ERAD to degrade major histocompatibility complex class I (MHC-I) molecules for immune evasion. Because US11 binds to both MHC-I molecules and Derlin-1 via its luminal and transmembrane domains (TMDs), respectively, the major role of US11 has been proposed to simply be delivery of MHC-I molecules to Derlin-1. Here, we directly tested this proposal by generating a hybrid MHC-I molecule, which contains the US11 TMD, and thus can associate with Derlin-1 in the absence of US11. Intriguingly, this MHC-I hybrid was rapidly degraded in a Derlin-1- and proteasome-dependent manner. Similarly, the vesicular stomatitis virus G protein, otherwise expressed at the cell surface, was degraded via Derlin-1-dependent ERAD when its TMD was replaced with that of US11. Thus, forced interaction of cell surface proteins with Derlin-1 is sufficient to induce their degradation via ERAD. Taken together, these results suggest that the main role of US11 is to recruit MHC-I molecules to Derlin-1, which then mediates the dislocation of MHC-I molecules into the cytosol for degradation. Copyright © 2012 Elsevier Inc. All rights reserved.

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

PubMed

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.

Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products.

PubMed

Yáñez, Jorge; Riffo, Paula; Santander, Paola; Mansilla, Héctor D; Mondaca, María Angélica; Campos, Víctor; Amarasiriwardena, Dulasiri

2015-07-01

Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation.

Cause and Effects of Fluorocarbon Degradation in Electronics and Opto-Electronic Systems

NASA Technical Reports Server (NTRS)

Predmore, Roamer E.; Canham, John S.

2002-01-01

Trace degradation of fluorocarbon or halocarbon materials must be addressed in their application in sensitive systems. As the dimensions and/or tolerances of components in a system decrease, the sensitivity of the system to trace fluorocarbon or halocarbon degradation products increases. Trace quantities of highly reactive degradation products from fluorocarbons have caused a number of failures of flight hardware. It is of utmost importance that the risk of system failure, resulting from trace amounts of reactive fluorocarbon degradation products be addressed in designs containing fluorocarbon or halocarbon materials. Thermal, electrical, and mechanical energy input into the system can multiply the risk of failure.

Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO2/CH4 Production Ratios

PubMed Central

Eiler, Alexander; Biasi, Christina; Tuittila, Eeva-Stiina; Yrjälä, Kim; Fritze, Hannu

2016-01-01

ABSTRACT Northern peatlands in general have high methane (CH4) emissions, but individual peatlands show considerable variation as CH4 sources. Particularly in nutrient-poor peatlands, CH4 production can be low and exceeded by carbon dioxide (CO2) production from unresolved anaerobic processes. To clarify the role anaerobic bacterial degraders play in this variation, we compared consumers of cellobiose-derived carbon in two fens differing in nutrient status and the ratio of CO2 to CH4 produced. After [13C]cellobiose amendment, the mesotrophic fen produced equal amounts of CH4 and CO2. The oligotrophic fen had lower CH4 production but produced 3 to 59 times more CO2 than CH4. RNA stable-isotope probing revealed that in the mesotrophic fen with higher CH4 production, cellobiose-derived carbon was mainly assimilated by various recognized fermenters of Firmicutes and by Proteobacteria. The oligotrophic peat with excess CO2 production revealed a wider variety of cellobiose-C consumers, including Firmicutes and Proteobacteria, but also more unconventional degraders, such as Telmatobacter-related Acidobacteria and subphylum 3 of Verrucomicrobia. Prominent and potentially fermentative Planctomycetes and Chloroflexi did not appear to process cellobiose-C. Our results show that anaerobic degradation resulting in different levels of CH4 production can involve distinct sets of bacterial degraders. By distinguishing cellobiose degraders from the total community, this study contributes to defining anaerobic bacteria that process cellulose-derived carbon in peat. Several of the identified degraders, particularly fermenters and potential Fe(III) or humic substance reducers in the oligotrophic peat, represent promising candidates for resolving the origin of excess CO2 production in peatlands. IMPORTANCE Peatlands are major sources of the greenhouse gas methane (CH4), yet in many peatlands, CO2 production from unresolved anaerobic processes exceeds CH4 production. Anaerobic degradation produces the precursors of CH4 production but also represents competing processes. We show that anaerobic degradation leading to high or low CH4 production involved distinct sets of bacteria. Well-known fermenters dominated in a peatland with high CH4 production, while novel and unconventional degraders could be identified in a site where CO2 production greatly exceeds CH4 production. Our results help identify and assign functions to uncharacterized bacteria that promote or inhibit CH4 production and reveal bacteria potentially producing the excess CO2 in acidic peat. This study contributes to understanding the microbiological basis for different levels of CH4 emission from peatlands. PMID:27913414

Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO2/CH4 Production Ratios.

PubMed

Juottonen, Heli; Eiler, Alexander; Biasi, Christina; Tuittila, Eeva-Stiina; Yrjälä, Kim; Fritze, Hannu

2017-02-15

Northern peatlands in general have high methane (CH 4 ) emissions, but individual peatlands show considerable variation as CH 4 sources. Particularly in nutrient-poor peatlands, CH 4 production can be low and exceeded by carbon dioxide (CO 2 ) production from unresolved anaerobic processes. To clarify the role anaerobic bacterial degraders play in this variation, we compared consumers of cellobiose-derived carbon in two fens differing in nutrient status and the ratio of CO 2 to CH 4 produced. After [ 13 C]cellobiose amendment, the mesotrophic fen produced equal amounts of CH 4 and CO 2 The oligotrophic fen had lower CH 4 production but produced 3 to 59 times more CO 2 than CH 4 RNA stable-isotope probing revealed that in the mesotrophic fen with higher CH 4 production, cellobiose-derived carbon was mainly assimilated by various recognized fermenters of Firmicutes and by Proteobacteria The oligotrophic peat with excess CO 2 production revealed a wider variety of cellobiose-C consumers, including Firmicutes and Proteobacteria, but also more unconventional degraders, such as Telmatobacter-related Acidobacteria and subphylum 3 of Verrucomicrobia Prominent and potentially fermentative Planctomycetes and Chloroflexi did not appear to process cellobiose-C. Our results show that anaerobic degradation resulting in different levels of CH 4 production can involve distinct sets of bacterial degraders. By distinguishing cellobiose degraders from the total community, this study contributes to defining anaerobic bacteria that process cellulose-derived carbon in peat. Several of the identified degraders, particularly fermenters and potential Fe(III) or humic substance reducers in the oligotrophic peat, represent promising candidates for resolving the origin of excess CO 2 production in peatlands. Peatlands are major sources of the greenhouse gas methane (CH 4 ), yet in many peatlands, CO 2 production from unresolved anaerobic processes exceeds CH 4 production. Anaerobic degradation produces the precursors of CH 4 production but also represents competing processes. We show that anaerobic degradation leading to high or low CH 4 production involved distinct sets of bacteria. Well-known fermenters dominated in a peatland with high CH 4 production, while novel and unconventional degraders could be identified in a site where CO 2 production greatly exceeds CH 4 production. Our results help identify and assign functions to uncharacterized bacteria that promote or inhibit CH 4 production and reveal bacteria potentially producing the excess CO 2 in acidic peat. This study contributes to understanding the microbiological basis for different levels of CH 4 emission from peatlands. Copyright © 2017 American Society for Microbiology.

Herbicides and herbicide degradation products in upper midwest agricultural streams during august base-flow conditions

USGS Publications Warehouse

Kalkhoff, S.J.; Lee, K.E.; Porter, S.D.; Terrio, P.J.; Thurman, E.M.

2003-01-01

Herbicide concentrations in streams of the U.S. Midwest have been shown to decrease through the growing season due to a variety of chemical and physical factors. The occurrence of herbicide degradation products at the end of the growing season is not well known. This study was conducted to document the occurrence of commonly used herbicides and their degradation products in Illinois, Iowa, and Minnesota streams during base-flow conditions in August 1997. Atrazine, the most frequently detected herbicide (94%), was present at relatively low concentrations (median 0.17 μg L−1). Metolachlor was detected in 59% and cyanazine in 37% of the samples. Seven of nine compounds detected in more than 50% of the samples were degradation products. The total concentration of the degradation products (median of 4.4 μg L−1) was significantly greater than the total concentration of parent compounds (median of 0.26 μg L−1). Atrazine compounds were present less frequently and in significantly smaller concentrations in streams draining watersheds with soils developed on less permeable tills than in watersheds with soils developed on more permeable loess. The detection and concentration of triazine compounds was negatively correlated with antecedent rainfall (April–July). In contrast, acetanalide compounds were positively correlated with antecedant rainfall in late spring and early summer that may transport the acetanalide degradates into ground water and subsequently into nearby streams. The distribution of atrazine degradation products suggests regional differences in atrazine degradation processes.

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

PubMed

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.

Thermal and catalytic degradation of high and low density polyethylene into fuel oil

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

Uddin, Azhar; Koizumi, Kazuo; Sakata, Yusaku

1996-12-31

The degradation of four different types of polyethylene (PE) namely high density PE (HDPE), low density PE (LDPE), linear low density PE (LLDPE), and cross-linked PE (XLPE) was carried out at 430 {degrees}C by batch operation using silica-alumina as a solid acid catalyst and thermally without any catalyst. For thermal degradation, both HDPE and XLPE produced significant amount of wax-like compounds and the yield of liquid products were lower than that of LDPE and LLDPE. LDPE and LLDPE also produced small amount of wax-like compounds. Thus the structure of the degrading polymers influenced the product yields. The liquid products frommore » thermal degradation were broadly distributed in the carbon fraction of n-C{sub 5} to n-C{sub 25} (boiling point range, 36-405 C). With silica-alumina, the polyethylenes were converted to liquid products with high yields (77-83 wt%) and without any wax production. The liquid products were distributed in the range of n-C{sub 5} to n-C{sub 20} (Mostly C{sub 5}-C{sub 12}). Solid acid catalyst indiscriminately degraded the various types of polyethylene into light fuel oil. 5 refs., 4 figs., 1 tab.« less

Role of RNase MRP in viral RNA degradation and RNA recombination.

PubMed

Jaag, Hannah M; Lu, Qiasheng; Schmitt, Mark E; Nagy, Peter D

2011-01-01

RNA degradation, together with RNA synthesis, controls the steady-state level of viral RNAs in infected cells. The endoribonucleolytic cleavage of viral RNA is important not only for viral RNA degradation but for RNA recombination as well, due to the participation of some RNA degradation products in the RNA recombination process. To identify host endoribonucleases involved in degradation of Tomato bushy stunt virus (TBSV) in a Saccharomyces cerevisiae model host, we tested eight known endoribonucleases. Here we report that downregulation of SNM1, encoding a component of the RNase MRP, and a temperature-sensitive mutation in the NME1 gene, coding for the RNA component of RNase MRP, lead to reduced production of the endoribonucleolytically cleaved TBSV RNA in yeast. We also show that the highly purified yeast RNase MRP cleaves the TBSV RNA in vitro, resulting in TBSV RNA degradation products similar in size to those observed in yeast cells. Knocking down the NME1 homolog in Nicotiana benthamiana also led to decreased production of the cleaved TBSV RNA, suggesting that in plants, RNase MRP is involved in TBSV RNA degradation. Altogether, this work suggests a role for the host endoribonuclease RNase MRP in viral RNA degradation and recombination.

Effect of vertical ground motions on shear demand and capacity in bridge columns.

DOT National Transportation Integrated Search

2012-03-01

The objective of this project was to examine the effects of axial force variation in bridge columns due to strong vertical : ground motions and the influence of these axial force fluctuations on shear strength degradation. : Two quarter scale specime...

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

PubMed

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

2016-08-05

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 (TiO2/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. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradation study of carnosic acid, carnosol, rosmarinic acid, and rosemary extract (Rosmarinus officinalis L.) assessed using HPLC.

PubMed

Zhang, Ying; Smuts, Jonathan P; Dodbiba, Edra; Rangarajan, Rekha; Lang, John C; Armstrong, Daniel W

2012-09-12

Rosemary, whose major caffeoyl-derived and diterpenoid ingredients are rosmarinic acid, carnosol, and carnosic acid, is an important source of natural antioxidants and is being recognized increasingly as a useful preservative, protectant, and even as a potential medicinal agent. Understanding the stability of these components and their mode of interaction in mixtures is important if they are to be utilized to greatest effect. A study of the degradation of rosmarinic acid, carnosol, carnosic acid, and a mixture of the three was conducted in ethanolic solutions at different temperatures and light exposure. As expected, degradation increased with temperature. Some unique degradation products were formed with exposure to light. Several degradation products were reported for the first time. The degradation products were identified by HPLC/MS/MS, UV, and NMR. The degradation of rosemary extract in fish oil also was investigated, and much slower rates of degradation were observed for carnosic acid. In the mixture of the three antioxidants, carnosic acid serves to maintain levels of carnosol, though it does so at least in part at the cost of its own degradation.

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

PubMed

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.

Identifying high production, low production and degraded rangelands in Senegal with normalized difference vegetation index data

USGS Publications Warehouse

Tappan, G. Gray; Wood, Lynette; Moore, Donald G.

1993-01-01

Seasonal herbaceous vegetation production on Senegal's native rangelands exhibits high spatial and temporal variability. This variability can be monitored using normalized difference vegetation index (NDVI) data computed from 1-km resolution Advanced Very High Resolution Radiometer (AVHRR) image data. Although annual fluctuations in rainfall account for some of the variability, numerous long-term production patterns are evident in the AVHRR time-series data. Different n productivity reflect variations in the region's climate, topography, soils, and land use. Areas of overgrazing and intensive cultivation have caused long-term soil and vegetation degradation. Rangelands of high and low productivity, and degraded rangelands were identified using NDVI. Time-series image data from 1987 though 1992 were used to map relative rangeland productivity. The results were compared to detailed resource maps on soils, vegetation and land use. Much of the variation in rangeland productivity correlated well to the known distribution of resources. The study developed an approach that identified a number of areas of degraded soils and low vegetation production.

Effect of pulsed electric field on the proteolysis of cold boned beef M. Longissimus lumborum and M. Semimembranosus.

PubMed

Suwandy, Via; Carne, Alan; van de Ven, Remy; Bekhit, Alaa El-Din A; Hopkins, David L

2015-02-01

The effects of pulsed electric field (PEF) and ageing (3, 7, 14 and 21 days) on the shear force, protein profile, and post-mortem proteolysis of beef loins (M. Longissimus lumborum, LL) and topsides (M. Semimembranosus, SM) were investigated using a range of pulsed electric field treatments [voltages (5 and 10 kV) and frequencies (20, 50, and 90 Hz)]. PEF treatment decreased the shear force of beef LL and SM muscles by up to 19%. The reduction in the shear force in the LL was not affected by the treatment intensity whereas the reduction in the SM was dependent on PEF frequency. PEF treated beef loins showed increased proteolysis, both early post-mortem and during subsequent post-mortem storage reflected by increased degradation of troponin-T and desmin. The most prominent troponin-T degradation was found in samples treated with 5 kV-90 Hz, 10 kV-20 Hz at day 3 and day 7 post-treatment in addition to 10 kV-50 Hz in subsequent post-treatment times. The degradation of desmin in PEF treated beef loins increased with ageing time.

The denaturation and degradation of stable enzymes at high temperatures.

PubMed Central

Daniel, R M; Dines, M; Petach, H H

1996-01-01

Now that enzymes are available that are stable above 100 degrees C it is possible to investigate conformational stability at this temperature, and also the effect of high-temperature degradative reactions in functioning enzymes and the inter-relationship between degradation and denaturation. The conformational stability of proteins depends upon stabilizing forces arising from a large number of weak interactions, which are opposed by an almost equally large destabilizing force due mostly to conformational entropy. The difference between these, the net free energy of stabilization, is relatively small, equivalent to a few interactions. The enhanced stability of very stable proteins can be achieved by an additional stabilizing force which is again equivalent to only a few stabilizing interactions. There is currently no strong evidence that any particular interaction (e.g. hydrogen bonds, hydrophobic interactions) plays a more important role in proteins that are stable at 100 degrees C than in those stable at 50 degrees C, or that the structures of very stable proteins are systematically different from those of less stable proteins. The major degradative mechanisms are deamidation of asparagine and glutamine, and succinamide formation at aspartate and glutamate leading to peptide bond hydrolysis. In addition to being temperature-dependent, these reactions are strongly dependent upon the conformational freedom of the susceptible amino acid residues. Evidence is accumulating which suggests that even at 100 degrees C deamidation and succinamide formation proceed slowly or not at all in conformationally intact (native) enzymes. Whether this is the case at higher temperatures is not yet clear, so it is not known whether denaturation of degradation will set the upper limit of stability for enzymes. PMID:8694749

Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species

NASA Astrophysics Data System (ADS)

Goodarzi, M.; Moosavi-Movahedi, A. A.; Habibi-Rezaei, M.; Shourian, M.; Ghourchian, H.; Ahmad, F.; Farhadi, M.; Saboury, A. A.; Sheibani, N.

2014-09-01

Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

Progress and obstacles in the production and application of recombinant lignin-degrading peroxidases

PubMed Central

Lambertz, Camilla; Ece, Selin; Fischer, Rainer; Commandeur, Ulrich

2016-01-01

ABSTRACT Lignin is 1 of the 3 major components of lignocellulose. Its polymeric structure includes aromatic subunits that can be converted into high-value-added products, but this potential cannot yet been fully exploited because lignin is highly recalcitrant to degradation. Different approaches for the depolymerization of lignin have been tested, including pyrolysis, chemical oxidation, and hydrolysis under supercritical conditions. An additional strategy is the use of lignin-degrading enzymes, which imitates the natural degradation process. A versatile set of enzymes for lignin degradation has been identified, and research has focused on the production of recombinant enzymes in sufficient amounts to characterize their structure and reaction mechanisms. Enzymes have been analyzed individually and in combinations using artificial substrates, lignin model compounds, lignin and lignocellulose. Here we consider progress in the production of recombinant lignin-degrading peroxidases, the advantages and disadvantages of different expression hosts, and obstacles that must be overcome before such enzymes can be characterized and used for the industrial processing of lignin. PMID:27295524

Attenuation of fluorocarbons released from foam insulation in landfills.

PubMed

Scheutz, Charlotte; Dote, Yutaka; Fredenslund, Anders M; Mosbaek, Hans; Kjeldsen, Peter

2007-11-15

Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) have been used as blowing agents (BAs) for foam insulation in home appliances and building materials, which after the end of their useful life are disposed of in landfills. The objective of this project was to evaluate the potential for degradation of BAs in landfills, and to develop a landfill model, which could simulate the fate of BAs in landfills. The investigation was performed by use of anaerobic microcosm studies using different types of organic waste and anaerobic digested sludge as inoculum. The BAs studied were CFC-11, CFC-12, HCFC-141b, HFC-134a, and HFC-245fa. Experiments considering the fate of some of the expected degradations products of CFC-11 and CFC-12 were included like HCFC-21, HCFC-22, HCFC-31, HCFC-32, and HFC-41. Degradation of all studied CFCs and HCFCs was observed regardless the type of waste used. In general, the degradation followed first-order kinetics. CFC-11 was rapidly degraded from 590 microg L(-1) to less than 5 microg L(-1) within 15-20 days. The degradation pattern indicated a sequential production of HCFC-21, HCFC-31, and HFC-41. However, the production of degradation products did not correlate with a stoichiometric removal of CFC-11 indicating that other degradation products were produced. HCFC-21 and HCFC-31 were further degraded whereas no further degradation of HFC-41 was observed. The degradation rate coefficient was directly correlated with the number of chlorine atoms attached to the carbon. The highest degradation rate coefficient was obtained for CFC-11, whereas lower rates were seen for HCFC-21 and HCFC-31. Equivalent results were obtained for CFC-12. HCFC-141b was also degraded with rates comparable to HCFC-21 and CFC-12. Anaerobic degradation of the studied HFCs was not observed in any of the experiments within a run time of up to 200 days. The obtained degradation rate coefficients were used as input for an extended version of an existing landfill fate model incorporating a time dependent BA release from co-disposed foam insulation waste. Predictions with the model indicate that the emission of foam released BAs may be strongly attenuated by microbial degradation reactions. Sensitivity analysis suggests that there is a need for determination of degradation rates under more field realistic scenarios.

Fatty Acid Structure and Degradation Analysis in Fingerprint Residues

NASA Astrophysics Data System (ADS)

Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

2016-09-01

GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl- N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints.

Fatty Acid Structure and Degradation Analysis in Fingerprint Residues.

PubMed

Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

2016-09-01

GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints. Graphical Abstract ᅟ.

Ultrasonic seam welding on thin silicon solar cells

NASA Technical Reports Server (NTRS)

Stofel, E. J.

1982-01-01

The ultrathin silicon solar cell has progressed to where it is a serious candidate for future light weight or radiation tolerant spacecraft. The ultrasonic method of producing welds was found to be satisfactory. These ultrathin cells could be handled without breakage in a semiautomated welding machine. This is a prototype of a machine capable of production rates sufficiently large to support spacecraft array assembly needs. For comparative purposes, this project also welded a variety of cells with thicknesses up to 0.23 mm as well as the 0.07 mm ultrathin cells. There was no electrical degradation in any cells. The mechanical pull strength of welds on the thick cells was excellent when using a large welding force. The mechanical strength of welds on thin cells was less since only a small welding force could be used without cracking these cells. Even so, the strength of welds on thin cells appears adequate for array application. The ability of such welds to survive multiyear, near Earth orbit thermal cycles needs to be demonstrated.

Stability of simulated flight path control at +3 Gz in a human centrifuge.

PubMed

Guardiera, Simon; Dalecki, Marc; Bock, Otmar

2010-04-01

Earlier studies have shown that naïve subjects and experienced jet pilots produce exaggerated manual forces when exposed to increased acceleration (+Gz). This study was designed to evaluate whether this exaggeration affects the stability of simulated flight path control. We evaluated naïve subjects' performance in a flight simulator which either remained stationary (+1 Gz), or rotated to induce an acceleration in accordance to the simulated flight path with a mean acceleration of about +3 Gz. In either case, subjects were requested to produce a series of altitude changes in pursuit of a visual target airplane. Resulting flight paths were analyzed to determine the largest oscillation after an altitude change (Oscillation) and the mean deviation between subject and target flight path (Tracking Error). Flight stability after an altitude change was degraded in +3 Gz compared to +1 Gz, as evidenced by larger Oscillations (+11%) and increased Tracking Errors (+80%). These deficits correlated significantly with subjects' +3 Gz deficits in a manual-force production task. We conclude that force exaggeration in +3 Gz may impair flight stability during simulated jet maneuvers in naïve subjects, most likely as a consequence of vestibular stimulation.

The interaction of force and repetition on musculoskeletal and neural tissue responses and sensorimotor behavior in a rat model of work-related musculoskeletal disorders

PubMed Central

2013-01-01

Background We examined the relationship of musculoskeletal risk factors underlying force and repetition on tissue responses in an operant rat model of repetitive reaching and pulling, and if force x repetition interactions were present, indicative of a fatigue failure process. We examined exposure-dependent changes in biochemical, morphological and sensorimotor responses occurring with repeated performance of a handle-pulling task for 12 weeks at one of four repetition and force levels: 1) low repetition with low force, 2) high repetition with low force, 3) low repetition with high force, and 4) high repetition with high force (HRHF). Methods Rats underwent initial training for 4–6 weeks, and then performed one of the tasks for 12 weeks, 2 hours/day, 3 days/week. Reflexive grip strength and sensitivity to touch were assayed as functional outcomes. Flexor digitorum muscles and tendons, forelimb bones, and serum were assayed using ELISA for indicators of inflammation, tissue stress and repair, and bone turnover. Histomorphometry was used to assay macrophage infiltration of tissues, spinal cord substance P changes, and tissue adaptative or degradative changes. MicroCT was used to assay bones for changes in bone quality. Results Several force x repetition interactions were observed for: muscle IL-1alpha and bone IL-1beta; serum TNFalpha, IL-1alpha, and IL-1beta; muscle HSP72, a tissue stress and repair protein; histomorphological evidence of tendon and cartilage degradation; serum biomarkers of bone degradation (CTXI) and bone formation (osteocalcin); and morphological evidence of bone adaptation versus resorption. In most cases, performance of the HRHF task induced the greatest tissue degenerative changes, while performance of moderate level tasks induced bone adaptation and a suggestion of muscle adaptation. Both high force tasks induced median nerve macrophage infiltration, spinal cord sensitization (increased substance P), grip strength declines and forepaw mechanical allodynia by task week 12. Conclusions Although not consistent in all tissues, we found several significant interactions between the critical musculoskeletal risk factors of force and repetition, consistent with a fatigue failure process in musculoskeletal tissues. Prolonged performance of HRHF tasks exhibited significantly increased risk for musculoskeletal disorders, while performance of moderate level tasks exhibited adaptation to task demands. PMID:24156755

The interaction of force and repetition on musculoskeletal and neural tissue responses and sensorimotor behavior in a rat model of work-related musculoskeletal disorders.

PubMed

Barbe, Mary F; Gallagher, Sean; Massicotte, Vicky S; Tytell, Michael; Popoff, Steven N; Barr-Gillespie, Ann E

2013-10-25

We examined the relationship of musculoskeletal risk factors underlying force and repetition on tissue responses in an operant rat model of repetitive reaching and pulling, and if force x repetition interactions were present, indicative of a fatigue failure process. We examined exposure-dependent changes in biochemical, morphological and sensorimotor responses occurring with repeated performance of a handle-pulling task for 12 weeks at one of four repetition and force levels: 1) low repetition with low force, 2) high repetition with low force, 3) low repetition with high force, and 4) high repetition with high force (HRHF). Rats underwent initial training for 4-6 weeks, and then performed one of the tasks for 12 weeks, 2 hours/day, 3 days/week. Reflexive grip strength and sensitivity to touch were assayed as functional outcomes. Flexor digitorum muscles and tendons, forelimb bones, and serum were assayed using ELISA for indicators of inflammation, tissue stress and repair, and bone turnover. Histomorphometry was used to assay macrophage infiltration of tissues, spinal cord substance P changes, and tissue adaptative or degradative changes. MicroCT was used to assay bones for changes in bone quality. Several force x repetition interactions were observed for: muscle IL-1alpha and bone IL-1beta; serum TNFalpha, IL-1alpha, and IL-1beta; muscle HSP72, a tissue stress and repair protein; histomorphological evidence of tendon and cartilage degradation; serum biomarkers of bone degradation (CTXI) and bone formation (osteocalcin); and morphological evidence of bone adaptation versus resorption. In most cases, performance of the HRHF task induced the greatest tissue degenerative changes, while performance of moderate level tasks induced bone adaptation and a suggestion of muscle adaptation. Both high force tasks induced median nerve macrophage infiltration, spinal cord sensitization (increased substance P), grip strength declines and forepaw mechanical allodynia by task week 12. Although not consistent in all tissues, we found several significant interactions between the critical musculoskeletal risk factors of force and repetition, consistent with a fatigue failure process in musculoskeletal tissues. Prolonged performance of HRHF tasks exhibited significantly increased risk for musculoskeletal disorders, while performance of moderate level tasks exhibited adaptation to task demands.

Cellulose Surface Degradation by a Lytic Polysaccharide Monooxygenase and Its Effect on Cellulase Hydrolytic Efficiency*

PubMed Central

Eibinger, Manuel; Ganner, Thomas; Bubner, Patricia; Rošker, Stephanie; Kracher, Daniel; Haltrich, Dietmar; Ludwig, Roland; Plank, Harald; Nidetzky, Bernd

2014-01-01

Lytic polysaccharide monooxygenase (LPMO) represents a unique principle of oxidative degradation of recalcitrant insoluble polysaccharides. Used in combination with hydrolytic enzymes, LPMO appears to constitute a significant factor of the efficiency of enzymatic biomass depolymerization. LPMO activity on different cellulose substrates has been shown from the slow release of oxidized oligosaccharides into solution, but an immediate and direct demonstration of the enzyme action on the cellulose surface is lacking. Specificity of LPMO for degrading ordered crystalline and unordered amorphous cellulose material of the substrate surface is also unknown. We show by fluorescence dye adsorption analyzed with confocal laser scanning microscopy that a LPMO (from Neurospora crassa) introduces carboxyl groups primarily in surface-exposed crystalline areas of the cellulosic substrate. Using time-resolved in situ atomic force microscopy we further demonstrate that cellulose nano-fibrils exposed on the surface are degraded into shorter and thinner insoluble fragments. Also using atomic force microscopy, we show that prior action of LPMO enables cellulases to attack otherwise highly resistant crystalline substrate areas and that it promotes an overall faster and more complete surface degradation. Overall, this study reveals key characteristics of LPMO action on the cellulose surface and suggests the effects of substrate morphology on the synergy between LPMO and hydrolytic enzymes in cellulose depolymerization. PMID:25361767

Failure Mechanisms of High Temperature Semiconductor Lasers

DTIC Science & Technology

1993-12-01

91 V.3.2. Facet Degradation 92 V.3.3. Dark Defect Degradation 95 V.3.4. Lasers Inoperational at Elevated Tempatur 96 V.3.5. Degradation Mechanism...they will be fairly easy to incorporate into the business of communications and control applications. The Air Force has a few of its own proposed uses ...demands a ho data processing Af~t which could be handled by lasems. A &W[ proposed use is a pilot chum•t-mo ited laer prwoicr to higgtthe portant dam2

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

PubMed

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.

Stochastic Modeling and Analysis of Multiple Nonlinear Accelerated Degradation Processes through Information Fusion.

PubMed

Sun, Fuqiang; Liu, Le; Li, Xiaoyang; Liao, Haitao

2016-08-06

Accelerated degradation testing (ADT) is an efficient technique for evaluating the lifetime of a highly reliable product whose underlying failure process may be traced by the degradation of the product's performance parameters with time. However, most research on ADT mainly focuses on a single performance parameter. In reality, the performance of a modern product is usually characterized by multiple parameters, and the degradation paths are usually nonlinear. To address such problems, this paper develops a new s-dependent nonlinear ADT model for products with multiple performance parameters using a general Wiener process and copulas. The general Wiener process models the nonlinear ADT data, and the dependency among different degradation measures is analyzed using the copula method. An engineering case study on a tuner's ADT data is conducted to demonstrate the effectiveness of the proposed method. The results illustrate that the proposed method is quite effective in estimating the lifetime of a product with s-dependent performance parameters.

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

NASA Astrophysics Data System (ADS)

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.

How does curcumin work with poor bioavailability? Clues from experimental and theoretical studies

NASA Astrophysics Data System (ADS)

Shen, Liang; Liu, Cui-Cui; An, Chun-Yan; Ji, Hong-Fang

2016-02-01

Curcumin is a natural product with multiple biological activities and numerous potential therapeutic applications. However, its poor systemic bioavailability fails to explain the potent pharmacological effects and hinders its clinical application. Using experimental and theoretical approaches, we compared curcumin and its degradation products for its biological activities against Alzheimer’s disease (AD), including the superoxide anion radical (O2.-)-scavenging activity, Aβ fibrils (fAβ) formation-inhibiting activity, and enzymatic inhibition activity. We showed that compared to the parent compound curcumin, the degradation products mixture possessed higher O2.--scavenging activity and stronger inhibition against fAβ formation. The docking simulations revealed that the bioactive degradation products should make important contribution to the experimentally observed enzymatic inhibition activities of curcumin. Given that curcumin is readily degraded under physiological condition, our findings strongly suggested that the degradation products should make important contribution to the diverse biological activities of curcumin. Our novel findings not only provide novel insights into the complex pharmacology of curcumin due to its poor bioavailability, but also open new avenues for developing therapeutic applications of this natural product.

Analysis of stability to cheaters in models of antibiotic degrading microbial communities.

PubMed

Szilágyi, András; Boza, Gergely; Scheuring, István

2017-06-21

Antibiotic resistance carried out by antibiotic degradation has been suggested recently as a new mechanism to maintain coexistence of microbial species competing on a single limiting resource, even in well-mixed homogeneous environments. Species diversity and community stability, however, critically depend on resistance against social cheaters, mutants that do not invest in production, but still enjoy the benefits provided by others. Here we investigate how different mutant cheaters affect the stability of antibiotic producing and degrading microbial communities. We consider two cheater types, production and degradation cheaters. We generalize the mixed inhibition-zone and chemostat models introduced previously [Kelsic, E. D., Zhao, J., Vetsigian, K., Kishony, R., 2015. Counteraction of an tibiotic production and degradation stabilizes microbial communities. Nature521, 516-519.] to study the population dynamics of microbial communities in well-mixed environment, and analyze the invasion of different cheaters in these models. We show that production cheaters, mutants that cease producing antibiotics, always destroy coexistence whenever there is a cost of producing these antibiotics. Degradation cheaters, mutants that loose their function of producing extracellular antibiotic degrading molecules, induce community collapse only if the cost of producing the degradation factors is above a critical level. Our analytical studies, supported by numerical simulations, highlight the sensitivity of antibiotic producing and degrading communities to loss-of-function mutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Always cleave up your mess: targeting collagen degradation to treat tissue fibrosis.

PubMed

McKleroy, William; Lee, Ting-Hein; Atabai, Kamran

2013-06-01

Pulmonary fibrosis is a vexing clinical problem with no proven therapeutic options. In the normal lung there is continuous collagen synthesis and collagen degradation, and these two processes are precisely balanced to maintain normal tissue architecture. With lung injury there is an increase in the rate of both collagen production and collagen degradation. The increase in collagen degradation is critical in preventing the formation of permanent scar tissue each time the lung is exposed to injury. In pulmonary fibrosis, collagen degradation does not keep pace with collagen production, resulting in extracellular accumulation of fibrillar collagen. Collagen degradation occurs through both extracellular and intracellular pathways. The extracellular pathway involves cleavage of collagen fibrils by proteolytic enzyme including the metalloproteinases. The less-well-described intracellular pathway involves binding and uptake of collagen fragments by fibroblasts and macrophages for lysosomal degradation. The relationship between these two pathways and their relevance to the development of fibrosis is complex. Fibrosis in the lung, liver, and skin has been associated with an impaired degradative environment. Much of the current scientific effort in fibrosis is focused on understanding the pathways that regulate increased collagen production. However, recent reports suggest an important role for collagen turnover and degradation in regulating the severity of tissue fibrosis. The objective of this review is to evaluate the roles of the extracellular and intracellular collagen degradation pathways in the development of fibrosis and to examine whether pulmonary fibrosis can be viewed as a disease of impaired matrix degradation rather than a disease of increased matrix production.

Always cleave up your mess: targeting collagen degradation to treat tissue fibrosis

PubMed Central

McKleroy, William; Lee, Ting-Hein

2013-01-01

Pulmonary fibrosis is a vexing clinical problem with no proven therapeutic options. In the normal lung there is continuous collagen synthesis and collagen degradation, and these two processes are precisely balanced to maintain normal tissue architecture. With lung injury there is an increase in the rate of both collagen production and collagen degradation. The increase in collagen degradation is critical in preventing the formation of permanent scar tissue each time the lung is exposed to injury. In pulmonary fibrosis, collagen degradation does not keep pace with collagen production, resulting in extracellular accumulation of fibrillar collagen. Collagen degradation occurs through both extracellular and intracellular pathways. The extracellular pathway involves cleavage of collagen fibrils by proteolytic enzyme including the metalloproteinases. The less-well-described intracellular pathway involves binding and uptake of collagen fragments by fibroblasts and macrophages for lysosomal degradation. The relationship between these two pathways and their relevance to the development of fibrosis is complex. Fibrosis in the lung, liver, and skin has been associated with an impaired degradative environment. Much of the current scientific effort in fibrosis is focused on understanding the pathways that regulate increased collagen production. However, recent reports suggest an important role for collagen turnover and degradation in regulating the severity of tissue fibrosis. The objective of this review is to evaluate the roles of the extracellular and intracellular collagen degradation pathways in the development of fibrosis and to examine whether pulmonary fibrosis can be viewed as a disease of impaired matrix degradation rather than a disease of increased matrix production. PMID:23564511

Screening of nitrogen mustards and their degradation products in water and decontamination solution by liquid chromatography-mass spectrometry.

PubMed

Chua, Hoe-Chee; Lee, Hoi-Sim; Sng, Mui-Tiang

2006-01-13

Analysing nitrogen mustards and their degradation products in decontamination emulsions posed a significant challenge due to the different phases present in such matrices. Extensive sample preparation may be required to isolate target analytes. Furthermore, numerous reaction products are formed in the decontamination emulsion. A fast and effective qualitative screening procedure was developed for these compounds, using liquid chromatography-mass spectrometry (LC-MS). This eliminated the need for additional sample handling and derivatisation that are required for gas chromatographic-mass spectrometric (GC-MS) analysis. A liquid chromatograph with mixed mode column and isocratic elution gave good chromatography. The feasibility of applying this technique for detecting these compounds in spiked water and decontamination emulsion was demonstrated. Detailed characterisation of the degradation products in these two matrices was carried out. The results demonstrated that N-methyldiethanolamine (MDEA), N-ethyldiethanolamine (EDEA) and triethanolamine (TEA) are not the major degradation products of their respective nitrogen mustards. Degradation profiles of nitrogen mustards in water were also established. In verification analysis, it is important not only to develop methods for the identification of the actual chemical agents; the methods must also encompass degradation products of the chemical agents as well so as to exclude false negatives. This study demonstrated the increasingly pivotal role that LC-MS play in verification analysis.

Teratogenicity of Ochratoxin A and the Degradation Product, Ochratoxin α, in the Zebrafish (Danio rerio) Embryo Model of Vertebrate Development

PubMed Central

Haq, Mehreen; Gonzalez, Nelson; Mintz, Keenan; Jaja-Chimedza, Asha; De Jesus, Christopher Lawrence; Lydon, Christina; Welch, Aaron Z.; Berry, John P.

2016-01-01

Ochratoxins, and particularly ochratoxin A (OTA), are toxic fungal-derived contaminants of food and other agricultural products. Growing evidence supports the degradation of OTA by chemical, enzymatic and/or microbial means as a potential approach to remove this mycotoxin from food products. In particular, hydrolysis of OTA to ochratoxin α (OTα) and phenylalanine is the presumptive product of degradation in most cases. In the current study, we employed the zebrafish (Danio rerio) embryo, as a model of vertebrate development to evaluate, the teratogenicity of OTA and OTα. These studies show that OTA is potently active in the zebrafish embryo toxicity assay (ZETA), and that toxicity is both concentration- and time-dependent with discernible and quantifiable developmental toxicity observed at nanomolar concentrations. On the other hand, OTα had no significant effect on embryo development at all concentrations tested supporting a decreased toxicity of this degradation product. Taken together, these results suggest that ZETA is a useful, and highly sensitive, tool for evaluating OTA toxicity, as well as its degradation products, toward development of effective detoxification strategies. Specifically, the results obtained with ZETA, in the present study, further demonstrate the toxicity of OTA, and support its degradation via hydrolysis to OTα as an effective means of detoxification. PMID:26861395

Teratogenicity of Ochratoxin A and the Degradation Product, Ochratoxin α, in the Zebrafish (Danio rerio) Embryo Model of Vertebrate Development.

PubMed

Haq, Mehreen; Gonzalez, Nelson; Mintz, Keenan; Jaja-Chimedza, Asha; De Jesus, Christopher Lawrence; Lydon, Christina; Welch, Aaron; Berry, John P

2016-02-05

Ochratoxins, and particularly ochratoxin A (OTA), are toxic fungal-derived contaminants of food and other agricultural products. Growing evidence supports the degradation of OTA by chemical, enzymatic and/or microbial means as a potential approach to remove this mycotoxin from food products. In particular, hydrolysis of OTA to ochratoxin α (OTα) and phenylalanine is the presumptive product of degradation in most cases. In the current study, we employed the zebrafish (Danio rerio) embryo, as a model of vertebrate development to evaluate, the teratogenicity of OTA and OTα. These studies show that OTA is potently active in the zebrafish embryo toxicity assay (ZETA), and that toxicity is both concentration- and time-dependent with discernible and quantifiable developmental toxicity observed at nanomolar concentrations. On the other hand, OTα had no significant effect on embryo development at all concentrations tested supporting a decreased toxicity of this degradation product. Taken together, these results suggest that ZETA is a useful, and highly sensitive, tool for evaluating OTA toxicity, as well as its degradation products, toward development of effective detoxification strategies. Specifically, the results obtained with ZETA, in the present study, further demonstrate the toxicity of OTA, and support its degradation via hydrolysis to OTα as an effective means of detoxification.

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

PubMed

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.

The apparent paradox of reestablishing species richness on degraded lands with tree monocultures.

Treesearch

Ariel E. Lugo

1997-01-01

The proliferation of degraded tropical landscapes in need of rehabilitation and the reduction of primary forest area have forced a closer collaboration between ecologist and land manager. this collaboration has led to new paradigms of forest management (combined in the term ecosystem management), new insight into forest ecology through comparative ecological...

Identification by CI-mass spectrometry of an unexpected benzodiazepine degradation product

NASA Astrophysics Data System (ADS)

Buret, D.; Breton, D.; Clair, P.; Lafosse, M.

2006-01-01

The French Military Health Service (SSA) has developed an innovative drug product, as a treatment against neurotoxic organophosphate poisoning (NOP). It contains three drug substances: an anticholinergic, an anticonvulsant and a cholinesterase reactivator. Testing stability study, in normal conditions, over 18 months, for this speciality, has given unexpected results. Indeed, one of the drug substances, avizafone (pro-drug of diazepam), breaks down partially into a compound which migrates into the plastic container where this degradation product is demethylated after absorption. Mass spectrometry with negative chemical ionisation (negative CI-MS) was used, to monitor decomposition of the drug substance. This method first showed migration of the degradation product and has been used to monitor its evolution during the stability testing study. The demethylation seems to be due to an additive product present in the plastic. The degradation products remain trapped in the container holding the pharmaceutical formulation.

Interconnections between mRNA degradation and RDR-dependent siRNA production in mRNA turnover in plants.

PubMed

Tsuzuki, Masayuki; Motomura, Kazuki; Kumakura, Naoyoshi; Takeda, Atsushi

2017-03-01

Accumulation of an mRNA species is determined by the balance between the synthesis and the degradation of the mRNA. Individual mRNA molecules are selectively and actively degraded through RNA degradation pathways, which include 5'-3' mRNA degradation pathway, 3'-5' mRNA degradation pathway, and RNA-dependent RNA polymerase-mediated mRNA degradation pathway. Recent studies have revealed that these RNA degradation pathways compete with each other in mRNA turnover in plants and that plants have a hidden layer of non-coding small-interfering RNA production from a set of mRNAs. In this review, we summarize the current information about plant mRNA degradation pathways in mRNA turnover and discuss the potential roles of a novel class of the endogenous siRNAs derived from plant mRNAs.

Silk-polypyrrole biocompatible actuator performance under biologically relevant conditions

NASA Astrophysics Data System (ADS)

Hagler, Jo'elen; Peterson, Ben; Murphy, Amanda; Leger, Janelle

Biocompatible actuators that are capable of controlled movement and can function under biologically relevant conditions are of significant interest in biomedical fields. Previously, we have demonstrated that a composite material of silk biopolymer and the conducting polymer polypyrrole (PPy) can be formed into a bilayer device that can bend under applied voltage. Further, these silk-PPy composites can generate forces comparable to human muscle (>0.1 MPa) making them ideal candidates for interfacing with biological tissues. Here silk-PPy composite films are tested for performance under biologically relevant conditions including exposure to a complex protein serum and biologically relevant temperatures. Free-end bending actuation performance, current response, force generation and, mass degradation were investigated . Preliminary results show that when exposed to proteins and biologically relevant temperatures, these silk-PPy composites show minimal degradation and are able to generate forces and conduct currents comparable to devices tested under standard conditions. NSF.

[Impact factors and degradation mechanism for the ozonation of acetaminophen in aqueous solution].

PubMed

Cao, Fei; Yuan, Shou-Jun; Zhang, Meng-Tao; Wang, Wei; Hu, Zhen-Hu

2014-11-01

The effect and mechanism of O3 on the degradation of acetaminophen in aqueous solution were studied by the batch experiment. The results showed that acetaminophen could be degraded effectively by ozone and degradation of acetaminophen fitted well with the pseudo-first-order kinetics model (R2 > 0.992). The degradation of acetaminophen was promoted with the increase of pH, the concentration of bicarbonate and ozone. The results of gas chromatography-mass spectrometry (GC-MS) and ion chromatography analysis showed that degradation products such as hydroquinone and a series of carboxylic acids were firstly formed during ozonation of acetaminophen. Then, the products were further oxidized. The degradation pathways of acetaminophen were also discussed by the identified products. The result of TOC showed that the mineralization of acetaminophen was ultimately lower. When the initial concentration of acetaminophen was 20 mg x L(-1) and the concentration of ozone was 9.10 mg x L(-1), the mineralization was only 16.42% after 130 min.

Physiology, biochemistry and possible applications of microbial caffeine degradation.

PubMed

Gummadi, Sathyanarayana N; Bhavya, B; Ashok, Nandhini

2012-01-01

Caffeine, a purine alkaloid is a constituent of widely consumed beverages. The scientific evidence which has proved the harm of this alkaloid has paved the way for innumerable research in the area of caffeine degradation. In addition to this, the fact that the by-products of the coffee and tea industry pollute the environment has called for the need of decaffeinating coffee and tea industry's by-products. Though physical and chemical methods for decaffeination are available, the lack of specificity for removal of caffeine in these techniques and their non-eco-friendly nature has opened the area of microbial and enzymatic degradation of caffeine. Another important application of microbial caffeine degradation apart from its advantages like specificity, eco-friendliness and cost-effectiveness is the fact that this process will enable the production of industrially and medically useful components of the caffeine degradation pathway like theobromine and theophylline. This is a comprehensive review which mainly focuses on caffeine degradation, large-scale degradation of the same and its applications in the industrial world.

Sonochemical Effects on 14 Flavonoids Common in Citrus: Relation to Stability

PubMed Central

Qiao, Liping; Sun, Yujing; Chen, Rongrong; Fu, Yu; Zhang, Wenjuan; Li, Xin; Chen, Jianchu; Shen, Yan; Ye, Xingqian

2014-01-01

The sonochemical effects of ultrasound (US) treatment on 14 flavonoids representing the main flavonoids in citrus fruit were investigated in a standard mixture by stability evaluation of a model system. Degradation products were further tentatively identified by Fourier transform infrared spectroscopy and high-performance liquid chromatography–ultraviolet detection–electrospray ionization tandem mass spectrometry. Thirteen flavonoids (i.e., eriocitrin, narirutin, neohesperidin, quercitrin, eridictyol, didymin, naringenin, luteolin, sinensetin, nobiletin, tangeretin, naringin, and hesperidin) were fairly stable whereas quercetin was degraded significantly by US treatment. The types of solvent and temperature used were important factors that determined the resulting degradation reactions. The degradation rate of quercetin was highest in 80% ethanol aqueous solution and decreased with increasing temperature. Longer US durations caused increases in the extent of quercetin degradation. Liquid height, ultrasonic intensity, pulse length, and duty cycle of US affected degradation rates but did not change the nature of degradation of the flavonoids. Four types of reactions occurred simultaneously for quercetin under US treatment: oxidation, addition, polymerization, and decomposition. Eight degradation products were tentatively identified as dimer, alcohol addition, oxidation, and decomposition products. PMID:24516562

Sonochemical effects on 14 flavonoids common in citrus: relation to stability.

PubMed

Qiao, Liping; Sun, Yujing; Chen, Rongrong; Fu, Yu; Zhang, Wenjuan; Li, Xin; Chen, Jianchu; Shen, Yan; Ye, Xingqian

2014-01-01

The sonochemical effects of ultrasound (US) treatment on 14 flavonoids representing the main flavonoids in citrus fruit were investigated in a standard mixture by stability evaluation of a model system. Degradation products were further tentatively identified by Fourier transform infrared spectroscopy and high-performance liquid chromatography-ultraviolet detection-electrospray ionization tandem mass spectrometry. Thirteen flavonoids (i.e., eriocitrin, narirutin, neohesperidin, quercitrin, eridictyol, didymin, naringenin, luteolin, sinensetin, nobiletin, tangeretin, naringin, and hesperidin) were fairly stable whereas quercetin was degraded significantly by US treatment. The types of solvent and temperature used were important factors that determined the resulting degradation reactions. The degradation rate of quercetin was highest in 80% ethanol aqueous solution and decreased with increasing temperature. Longer US durations caused increases in the extent of quercetin degradation. Liquid height, ultrasonic intensity, pulse length, and duty cycle of US affected degradation rates but did not change the nature of degradation of the flavonoids. Four types of reactions occurred simultaneously for quercetin under US treatment: oxidation, addition, polymerization, and decomposition. Eight degradation products were tentatively identified as dimer, alcohol addition, oxidation, and decomposition products.

The IGF-I/IGFBP-3 system in gingival crevicular fluid and dependence on application of fixed force.

PubMed

Toia, M; Galazzo, R; Maioli, C; Granata, R; Scarlatti, F

2005-12-01

During application of orthodontic force on the tooth, various molecular parameters associated with tissue remodeling are changed. IGF-I is a regulatory protein produced during periodontal regeneration. IGF binding proteins-3 (IGFBP-3), a specific IGF-I binding protein, is the major regulatory factor of IGF-I activity. We tested the hypothesis that changes in the IGF-I/ IGFBP-3 system occur during fixed force application to the tooth and that these changes are detectable in the gingival crevicular fluid (GCF). IGFBP-3 and IGF-I secretion into gingival crevicular fluid (GCF) was analyzed by Western blotting and immunoradiometric assay (IRMA), respectively, in GCF of 6 healthy subjects just prior to and during orthodontics treatment using fixed appliances. We observed a significant time-dependent decrease of IGFBP-3 content in GCF during orthodontic treatment (4 h and 10 days). Reduction in levels of intact, glycosylated 47 kDa form of IGFBP-3 was associated with its degradation and the appearance of intermediate breakdown products. IGF-I levels were significantly increased 4 h after application of orthodontic force, while they were significantly reduced 10 days after the start of treatment. IGFBP-3 secretion into GCF and its molecular structure are modified by the fixed force of orthodontic treatment. Alterations in IGFBP-3 appear to be unrelated to the binding to IGF-I, suggesting an IGF-independent role of this binding protein in tooth movement.

Transformation products of amoxicillin and ampicillin after photolysis in aqueous matrices: Identification and kinetics.

PubMed

Arsand, Juliana Bazzan; Hoff, Rodrigo Barcellos; Jank, Louise; Meirelles, Lucas N; Silvia Díaz-Cruz, M; Pizzolato, Tânia Mara; Barceló, Damià

2018-06-18

Antibiotics are widely used in human medicine and veterinary production. Residues of these compounds reach the water sources through waste or direct application (e.g. aquaculture). The constant input of the parent drugs and their transformation products into the environment leads these pharmaceuticals to be considered as emerging pollutants. For some molecules, the pathway of degradation and formation in products is less known. To assess the impact of these substances in the environment and in the human health, it is necessary to elucidate the transformation products and their kinetic of degradation to evaluate the possible risks. In the present report, the characterization and the degradation kinetic of two widely used β-lactams antibiotics - amoxicillin and ampicillin - was evaluated. Surface water samples containing these antibiotics were submitted to photolysis and analyzed by liquid chromatography coupled to mass spectrometry with Orbitrap detection in order to establish the profile of degradation and the formation of transformation products. Results showed that the degradation of amoxicillin and ampicillin is almost complete and reach their maximum at 48 h in river water. Moreover, a database containing >65 transformation products of amoxicillin and ampicillin was build and real samples of industrial wastewater were analyzed to investigate the occurrence of amoxicillin, ampicillin and their transformation products. Copyright © 2018. Published by Elsevier B.V.

Gamma irradiation assisted fungal degradation of the polypropylene/biomass composites

NASA Astrophysics Data System (ADS)

Butnaru, Elena; Darie-Niţă, Raluca Nicoleta; Zaharescu, Traian; Balaeş, Tiberius; Tănase, Cătălin; Hitruc, Gabriela; Doroftei, Florica; Vasile, Cornelia

2016-08-01

White-rot fungus Bjerkandera adusta has been tested for its ability to degrade some biocomposites materials based on polypropylene and biomass (Eucalyptus globulus, pine cones, and Brassica rapa). γ-irradiation was applied to initiate the degradation of relatively inert polypropylene matrix. The degradation process has been studied by scanning electron microscopy, atomic force microscopy, infrared spectroscopy, contact angle measurements, rheological and chemiluminescence tests. These analyses showed that the polypropylene/biomass composites properties are worsen under the action of the selected microorganism. The formation of cracks and scrap particles over the entire matrix surface and the decrease of the complex viscosity values, as well as the dynamic moduli of gamma irradiated PP/biomass composite and exposed to Bjerkandera adusta fungus, indicate fungal efficiency in composite degradation.

Development and Validation of a Stability-indicating Reversed-phase UPLC-UV Method for the Assay of Imidacloprid and Estimation of its Related Compounds.

PubMed

Tian, Jingzhi; Rustum, Abu

2018-02-01

Imidacloprid is used as an active pharmaceutical ingredient (API) in veterinary drugs to control fleas and ticks for dogs and cats. Here we are reporting for the first time a validated stability-indicating reversed-phase UPLC-UV method for the assay of imidacloprid and estimation of its related compounds. The stability-indicating capability of this method has been demonstrated by a forced degradation study. All related compounds including processing impurities, imidacloprid API and degradates from stressed samples were well separated from each other. Structures of major degradates from forced degradation study were elucidated through UPLC-MS/MS and key degradation pathways were proposed from the proposed chemical structures of major degradates. The UPLC-UV method is carried out using an HSS T3 column (C18, 2.1 × 30 mm, 1.8 μm particle size) maintained at 30°C with mobile phase A (0.05% v/v of phosphoric acid in water) and mobile phase B (methanol/acetonitrile 75/25 v/v). Analytes are separated by a gradient elution and detected at 270 nm. The UPLC method is green and fast with only 6.5 min run time and about 3.5 ml mobile phase consumption for each sample analysis. The UPLC-UV method was validated according to ICH guidelines. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Degradation of Histamine by Lactobacillus plantarum Isolated from Miso Products.

PubMed

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.

Quantitating protein synthesis, degradation, and endogenous antigen processing.

PubMed

Princiotta, Michael F; Finzi, Diana; Qian, Shu-Bing; Gibbs, James; Schuchmann, Sebastian; Buttgereit, Frank; Bennink, Jack R; Yewdell, Jonathan W

2003-03-01

Using L929 cells, we quantitated the macroeconomics of protein synthesis and degradation and the microeconomics of producing MHC class I associated peptides from viral translation products. To maintain a content of 2.6 x 10(9) proteins, each cell's 6 x 10(6) ribosomes produce 4 x 10(6) proteins min(-1). Each of the cell's 8 x 10(5) proteasomes degrades 2.5 substrates min(-1), creating one MHC class I-peptide complex for each 500-3000 viral translation products degraded. The efficiency of complex formation is similar in dendritic cells and macrophages, which play a critical role in activating T cells in vivo. Proteasomes create antigenic peptides at different efficiencies from two distinct substrate pools: rapidly degraded newly synthesized proteins that clearly represent defective ribosomal products (DRiPs) and a less rapidly degraded pool in which DRiPs may also predominate.

Enrofloxacin degradation in broiler chicken manure under field conditions and its residuals effects to the environment.

PubMed

Slana, M; Žigon, D; Sollner-Dolenc, M

2017-05-01

The rate of degradation of enrofloxacin in broiler chicken manure has been characterised. Its degradation was investigated in manure excreted by broiler chickens in an intensively reared chicken facility; further, the degradation also followed after transfer of the excreta into the natural environment occurred. The effect of enrofloxacin and its degradation products on cucumber and tomato was also investigated. Enrofloxacin degradation was shown to take place within the rearing facility and also continuing after the manure was transferred into the environment. The rates of enrofloxacin degradation and the degree of degradation product formation in the manure heap incubated in the environment were condition specific, both variables depending on the manure sampling depth. The degradation half-lives ranged from 12.7 to 38.1 days for enrofloxacin and from 1.2 to 8.2 days for the main metabolite ciprofloxacin. Only the cucumber showed signs of toxicity when incubated with the composted manure immediately after transfer into field occurred (t = 0). No toxic effects to plants were observed when manure from the last incubation day (60th) of the field study and manure from the last incubation day of the laboratory degradation study were applied. The degradation study under field conditions showed that enrofloxacin and its degradation products degrade fast in the environment. Additionally, the toxic effects to plants decrease with the incubation time of manure containing enrofloxacin residuals.

Development and validation of a stability-indicating capillary zone electrophoretic method for the assessment of entecavir and its correlation with liquid chromatographic methods.

PubMed

Dalmora, Sergio Luiz; Nogueira, Daniele Rubert; D'Avila, Felipe Bianchini; Souto, Ricardo Bizogne; Leal, Diogo Paim

2011-01-01

A stability-indicating capillary zone electrophoresis (CZE) method was validated for the analysis of entecavir in pharmaceutical formulations, using nimesulide as an internal standard. A fused-silica capillary (50 µm i.d.; effective length, 40 cm) was used while being maintained at 25°C; the applied voltage was 25 kV. A background electrolyte solution consisted of a 20 mM sodium tetraborate solution at pH 10. Injections were performed using a pressure mode at 50 mbar for 5 s, with detection at 216 nm. The specificity and stability-indicating capability were proven through forced degradation studies, evaluating also the in vitro cytotoxicity test of the degraded products. The method was linear over the concentration range of 1-200 µg mL(-1) (r(2) = 0.9999), and was applied for the analysis of entecavir in tablet dosage forms. The results were correlated to those of validated conventional and fast LC methods, showing non-significant differences (p > 0.05).

Stability indicating simplified HPLC method for simultaneous analysis of resveratrol and quercetin in nanoparticles and human plasma.

PubMed

Kumar, Sandeep; Lather, Viney; Pandita, Deepti

2016-04-15

Resveratrol and quercetin are well-known polyphenolic compounds present in common foods, which have demonstrated enormous potential in the treatment of a wide variety of diseases. Owing to their exciting synergistic potential and combination delivery applications, we developed a simple and rapid RP-HPLC method based on isosbestic point detection. The separation was carried out on phenomenex Synergi 4μ Hydro-RP 80A column using methanol: acetonitrile (ACN): 0.1% phosphoric acid (60:10:30) as mobile phase. The method was able to quantify nanograms of analytes simultaneously on a single wavelength (269 nm), making it highly sensitive, rapid as well as economical. Additionally, forced degradation studies of resveratrol and quercetin were established and the method's applicability was evaluated on PLGA nanoparticles and human plasma. The analytes peaks were found to be well resolved in the presence of degradation products and excipients. The simplicity of the developed method potentializes its suitability for routine in vitro and in vivo analysis of resveratrol and quercetin. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recent ecological transitions in China: greening, browning, and influential factors

NASA Astrophysics Data System (ADS)

Lü, Yihe; Zhang, Liwei; Feng, Xiaoming; Zeng, Yuan; Fu, Bojie; Yao, Xueling; Li, Junran; Wu, Bingfang

2015-03-01

Ecological conservation and restoration are necessary to mitigate environmental degradation problems. China has taken great efforts in such actions. To understand the ecological transition during 2000-2010 in China, this study analysed trends in vegetation change using remote sensing and linear regression. Climate and socioeconomic factors were included to screen the driving forces for vegetation change using correlation or comparative analyses. Our results indicated that China experienced both vegetation greening (restoration) and browning (degradation) with great spatial heterogeneity. Socioeconomic factors, such as human populations and economic production, were the most significant factors for vegetation change. Nature reserves have contributed slightly to the deceleration of vegetation browning and the promotion of greening; however, a large-scale conservation approach beyond nature reserves was more effective. The effectiveness of the Three-North Shelter Forest Program lay between the two above approaches. The findings of this study highlighted that vegetation trend detection is a practical approach for large-scale ecological transition assessments, which can inform decision-making that promotes vegetation greening via proper socioeconomic development and ecosystem management.

Recent ecological transitions in China: greening, browning, and influential factors.

PubMed

Lü, Yihe; Zhang, Liwei; Feng, Xiaoming; Zeng, Yuan; Fu, Bojie; Yao, Xueling; Li, Junran; Wu, Bingfang

2015-03-04

Ecological conservation and restoration are necessary to mitigate environmental degradation problems. China has taken great efforts in such actions. To understand the ecological transition during 2000-2010 in China, this study analysed trends in vegetation change using remote sensing and linear regression. Climate and socioeconomic factors were included to screen the driving forces for vegetation change using correlation or comparative analyses. Our results indicated that China experienced both vegetation greening (restoration) and browning (degradation) with great spatial heterogeneity. Socioeconomic factors, such as human populations and economic production, were the most significant factors for vegetation change. Nature reserves have contributed slightly to the deceleration of vegetation browning and the promotion of greening; however, a large-scale conservation approach beyond nature reserves was more effective. The effectiveness of the Three-North Shelter Forest Program lay between the two above approaches. The findings of this study highlighted that vegetation trend detection is a practical approach for large-scale ecological transition assessments, which can inform decision-making that promotes vegetation greening via proper socioeconomic development and ecosystem management.

Design and stability study of a paediatric oral solution of methotrexate 2 mg/ml.

PubMed

Vrignaud, Sandy; Briot, Thomas; Launay, Aurélie; Kempf, Marie; Lagarce, Frédéric

2015-06-20

Oral paediatric forms development by pharmaceutical industry is still insufficient. The present study was performed to propose an adapted and pleasant formulation of liquid oral formulation of MTX. The solution is composed of injectable methotrexate, water, Ora Sweet(®) and sodium bicarbonate. After 120 days storage, pH remained stable at about 8 in all formulations, insuring no risk of MTX precipitation. MTX content in solution formulation, determined by high performance liquid chromatography measurements, remained in the specifications of >90% of the initial concentration when stored at 4 and 25°C. Forced degradation of MTX by heat and acidic conditions allowed formation and detection of degradation products by the analytical method. Microbial study of the preparation shows that the solution remains in the specifications during all the storage, or after one sample each week during one month, eventually indicating the microbial properties are not affected by patient use. To conclude, we here propose a new MTX liquid formulation stable for at least 120 days. Copyright © 2015 Elsevier B.V. All rights reserved.

The effects of the antibiotics ampicillin, florfenicol, sulfamethazine, and tylosin on biogas production and their degradation efficiency during anaerobic digestion.

PubMed

Mitchell, Shannon M; Ullman, Jeffrey L; Teel, Amy L; Watts, Richard J; Frear, Craig

2013-12-01

The impacts of four common animal husbandry antibiotics (ampicillin, florfenicol, sulfamethazine, and tylosin) on anaerobic digestion (AD) treatment efficiency and the potential for antibiotic degradation during digestion were evaluated. Sulfamethazine and ampicillin exhibited no impact on total biogas production up to 280 and 350 mg/L, respectively, although ampicillin inhibited biogas production rates during early stages of AD. Tylosin reduced biogas production by 10-38% between 130 and 913 mg/L. Florfenicol reduced biogas by ≈ 5%, 40% and 75% at 6.4, 36 and 210 mg/L, respectively. These antibiotic concentrations are higher than commonly seen for mixed feedlot manure, so impacts on full scale AD should be minimal. Antibiotic degradation products were found, confirming AD effectively degraded ampicillin, florfenicol, and tylosin, although some products were persistent throughout the process. Contamination of AD solid and liquid effluents with sulfamethazine and antibiotic transformation products from florfenicol and tylosin could present an environmental concern. Published by Elsevier Ltd.

First derivative spectrophotometric and LC determination of benoxinate hydrochloride and its degradation products.

PubMed

El-Gindy, A

2000-03-01

Two methods are presented for the determination of benoxinate HCI and its acid and alkali-induced degradation products using first derivative (1D) spectrophotometry with zero-crossing measurements and liquid chromatography. Benoxinate HCl was determined by measurement of its first derivative amplitude in mcllvaine's-citric acid phosphate buffer pH 7.0 at 268.4 and 272.4 nm in the presence of its alkali- and acid-induced degradation products, respectively. The acid- and alkali-induced, degradation products were determined by measurement of their first derivative amplitude in the same solvent at 307.5 nm. The LC method depends upon using a mu bondapak CN column with a mobile phase consisting of acetonitrile-water triethylamine (60:40:0.01, v/v) and adjusted to apparent pH 7. Quantitation was achieved with UV detection at 310 nm based on peak area. The proposed methods were utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures. The pH-rate profile of degradation of benoxinate HCl in Britton-Robinson buffer solutions was studied.

Possibilities for developing texture-modified beef steaks suitable for older consumers using fruit-derived proteolytic enzymes.

PubMed

Botinestean, Cristina; Gomez, Carolina; Nian, Yingqun; Auty, Mark A E; Kerry, Joseph P; Hamill, Ruth M

2018-06-01

Meat intakes in the older population are commonly reduced because the relatively tough texture of meat can impair mastication. Fruit-derived proteolytic enzymes have been reported to have beneficial effects on tenderness, by causing significant degradation of myofibrillar proteins and collagen. Three treatments including: papain, bromelain, and a 50:50 mixture of papain/bromelain, alongside one control were applied to beef M. semitendinosus steaks. Effects on Warner-Bratzler shear force, texture parameters, color, and cook loss were determined. Both enzymatic treatments that included papain significantly reduced Warner-Bratzler shear force values (p < .05) and increased cook loss. Beef steaks tenderized with papain and papain/bromelain offer potential for inclusion in older consumers' diets, but improvement in tenderization may be associated with a reduction in processing yield. Meat processors have a role to play in enhancing the availability of appropriate foodstuffs for older people, through developing targeted products that will meet the specialized nutritional and chemosensory needs of this cohort. Meat intakes in the older population are commonly reduced because the relatively tough texture of meat can impair mastication. In this study, beef steaks tenderized with papain and papain: bromelain (50:50) were demonstrated to produce more tender meat products, with a lower cook loss compared with tenderization with bromelain alone, which has relevance to the development of texture-optimized meat products that appeal to older adults with difficulty in mastication. This information could help meat processors to develop strategies for optimization of texture-modified beef products within their own businesses. © 2017 Wiley Periodicals, Inc.

Results of analyses of the fungicide Chlorothalonil, its degradation products, and other selected pesticides at 22 surface-water sites in five Southern states, 2003-04

USGS Publications Warehouse

Scribner, Elisabeth A.; Orlando, James L.; Battaglin, William A.; Sandstrom, Mark; Kuivila, Kathryn; Meyer, Michael T.

2006-01-01

In accordance with the mission of the U.S. Geological Survey (USGS) Toxic Substances Hydrology Program, a pesticide study was conducted during 2003-04 to determine the occurrence of the fungicide chlorothalonil and its degradation products at 22 surface-water sites in five Southern States. Water-quality samples were collected during the peanut-growing season (June-September) in 2003. During the peanut-growing season in 2004, samples were collected after large storms. An analytical method was developed at the USGS Organic Geochemistry Research Laboratory in Lawrence, Kansas, to measure chlorothalonil and its degradation products by liquid chromatography/mass spectrometry (LC/MS). Chlorothalonil was detected in 4 of the 113 surface-water samples. The primary degradation product of chlorothalonil, 4-hydroxy-chlorothalonil, was detected in 26 of the 113 samples with concentrations ranging from 0.002 to 0.930 microgram per liter. The chlorothalonil degradation products, 1-amide-4-hydroxy-chorothalonil and 1,3-diamide-chlorothalonil, were detected in one water sample each at 0.020 and 0.161 microgram per liter, respectively. The USGS Methods and Research Development Group, Lakewood, Colorado, developed a custom method for chlorothalonil using gas chromatography/mass spectrometry (GC/MS) in an effort to achieve a lower laboratory reporting level (LRL) than the USGS National Water-Quality Laboratory (NWQL) schedule 2060, which analyzes the compound chlorothalonil at a LRL of 0.035 ?g/L. The group succeeded in achieving a lower GC/MS reporting level of 0.01 ?g/L. Chlorothalonil was detected in 5 of 68 water samples analyzed using the custom GC/MS method, whereas chlorothalonil was detected in 2 of 21 water samples analyzed using NWQL schedule 2060. In addition to analysis of chlorothalonil and its degradation products, samples were analyzed using the USGS NWQL schedules 2001 and 2060 for about 114 pesticides and their degradation products. Samples also were analyzed for dissolved organic carbon, suspended sediment, and percentage of silt- and clay-sized particles. Overall, it was found that chlorothalonil was detected only infrequently and at relatively low concentrations. Chlorothalonil's major degradation product, 4-hydroxy-chlorothalonil, was detected most frequently, occurred generally at higher concentrations in water samples than did the parent fungicide, and the data from this study reaffirmed that it is the dominant degradation product of chlorothalonil in the peanut-growing environment.

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

PubMed

Lobbens, Eva S; Foderà, Vito; Nyberg, Nils T; Andersen, Kirsten; Jäger, Anna K; Jorgensen, Lene; van de Weert, Marco

2016-01-01

Protein fibrillation is the pathological hallmark of several neurodegenerative diseases and also complicates the manufacturing and use of protein drugs. As a case study, the inhibitory activity of the natural compound aloin against insulin fibrillation was investigated. Based on Thioflavin T assays, 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 compounds in the solution were aloin A and aloin B. In addition, 10-hydroxy aloin and elgonica dimers were detected in smaller amounts. The identified compounds were isolated and tested for activity by means of Thioflavin T assays, but no activity was observed. Thus, the actual fibrillation inhibitor is an as yet unidentified and potentially metastable degradation product of aloin. These results suggest that degradation products, and in particular oxidation products, are to be considered thoroughly when natural products are investigated for activity against protein fibrillation.

Use of Activated Carbon in Packaging to Attenuate Formaldehyde-Induced and Formic Acid-Induced Degradation and Reduce Gelatin Cross-Linking in Solid Dosage Forms.

PubMed

Colgan, Stephen T; Zelesky, Todd C; Chen, Raymond; Likar, Michael D; MacDonald, Bruce C; Hawkins, Joel M; Carroll, Sophia C; Johnson, Gail M; Space, J Sean; Jensen, James F; DeMatteo, Vincent A

2016-07-01

Formaldehyde and formic acid are reactive impurities found in commonly used excipients and can be responsible for limiting drug product shelf-life. Described here is the use of activated carbon in drug product packaging to attenuate formaldehyde-induced and formic acid-induced drug degradation in tablets and cross-linking in hard gelatin capsules. Several pharmaceutical products with known or potential vulnerabilities to formaldehyde-induced or formic acid-induced degradation or gelatin cross-linking were subjected to accelerated stability challenges in the presence and absence of activated carbon. The effects of time and storage conditions were determined. For all of the products studied, activated carbon attenuated drug degradation or gelatin cross-linking. This novel use of activated carbon in pharmaceutical packaging may be useful for enhancing the chemical stability of drug products or the dissolution stability of gelatin-containing dosage forms and may allow for the 1) extension of a drug product's shelf-life when the limiting attribute is a degradation product induced by a reactive impurity, 2) marketing of a drug product in hotter and more humid climatic zones than currently supported without the use of activated carbon, and 3) enhanced dissolution stability of products that are vulnerable to gelatin cross-linking. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Community air monitoring for pesticides. Part 3: using health-based screening levels to evaluate results collected for a year.

PubMed

Wofford, Pamela; Segawa, Randy; Schreider, Jay; Federighi, Veda; Neal, Rosemary; Brattesani, Madeline

2014-03-01

The CA Department of Pesticide Regulation (CDPR) and the CA Air Resources Board monitored 40 pesticides, including five degradation products, in Parlier, CA, to determine if its residents were exposed to any of these pesticides and, if so, in what amounts. They included 1,3-dichloropropene, acrolein, arsenic, azinphos-methyl, carbon disulfide, chlorpyrifos and its degradation product, chlorthalonil, copper, cypermethrin, diazinon and its degradation product, dichlorvos, dicofol, dimethoate and its degradation product, diuron, endosulfan and its degradation product, S-ethyl dipropylcarbamothioate (EPTC), formaldehyde, malathion and its degradation product, methyl isothiocyanate (MITC), methyl bromide, metolachlor, molinate, norflurazon, oryzalin, oxyfluorfen, permethrin, phosmet, propanil, propargite, simazine, SSS-tributylphosphorotrithioate, sulfur, thiobencarb, trifluralin, and xylene. Monitoring was conducted 3 days per week for a year. Twenty-three pesticides and degradation products were detected. Acrolein, arsenic, carbon disulfide, chlorpyrifos, copper, formaldehyde, methyl bromide, MITC, and sulfur were detected in more than half the samples. Since no regulatory ambient air standards exist for these pesticides, CDPR developed advisory, health-based non-cancer screening levels (SLs) to assess acute, subchronic, and chronic exposures. For carcinogenic pesticides, CDPR assessed risk using cancer potency values. Amongst non-carcinogenic agricultural use pesticides, only diazinon exceeded its SL. For carcinogens, 1,3-dichloropropene concentrations exceeded its cancer potency value. Based on these findings, CDPR has undertaken a more comprehensive evaluation of 1,3-dichloropropene, diazinon, and the closely related chlorpyrifos that was frequently detected. Four chemicals-acrolein, arsenic, carbon disulfide, and formaldehyde-sometimes used as pesticides were detected, although no pesticidal use was reported in the area during this study. Their presence was most likely due to vehicular or industrial emissions.

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

PubMed Central

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 evaluation of both the agent and thiodiglycol. Images Figure 1 Figure 3 Figure 5 PMID:10585900

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group : determination of selected herbicides and their degradation products in water using solid-phase extraction and gas chromatography/mass spectrometry

USGS Publications Warehouse

Kish, J.L.; Thurman, E.M.; Scribner, E.A.; Zimmerman, L.R.

2000-01-01

A method for the extraction and analysis of eight herbicides and five degradation products using solid-phase extraction from natural water samples followed by gas chromatography/mass spectrometry is presented in this report. This method was developed for dimethenamid; flufenacet; fluometuron and its degradation products, demethylfluometuron (DMFM), 3-(trifluromethyl)phenylurea (TFMPU), 3-(trifluromethyl)-aniline (TFMA); molinate; norflurazon and its degradation product, demethylnorflurazon; pendamethalin; the degradation product of prometryn, deisopropylprometryn; propanil; and trifluralin. The eight herbicides are used primarily in the southern United States where cotton, rice, and soybeans are produced. The exceptions are dimethenamid and flufenacet, which are used on corn in the Midwest. Water samples received by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas, are filtered to remove suspended particulate matter and then passed through disposable solid-phase extraction columns containing octadecyl-bonded porous silica (C-18) to extract the compounds. The herbicides and their degradation products are removed from the column by ethyl acetate elution. The eluate is evaporated under nitrogen, and components then are separated, identified, and quantified by injecting an aliquot of the concentrated extract into a high-resolution, fused-silica capillary column of a gas chromatograph/mass spectrometer under selected-ion mode. Method detection limits ranged from 0.02 to 0.05 ?g/L for all compounds with the exception of TFMPU, which has a method detection limit of 0.32 ?g/L. The mean absolute recovery is 107 percent. This method for the determination of herbicides and their degradation products is valuable for acquiring information about water quality and compound fate and transport in water.

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

NASA Astrophysics Data System (ADS)

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.

Interdependence of population and environment on sustainable development: what stake do women have?

PubMed

Thapa, S R

1997-07-01

This article reviews women's role in the development process in Nepal. Nepal's government has made a commitment to sustainable development. There was participation in all the Earth Summits and international conferences. The 9th 5-Year Plan is ready and includes strategies for ameliorating poverty, stemming population growth, and stopping environmental degradation and natural resource depletion. Women have been increasing their role in achieving sustainable development. Women need water and energy in order to fulfill their role as caretakers of children and the family. Women contribute to sustainable development by actively producing agricultural products and raising livestock. About 60% of the agricultural labor force is comprised of women. About 90% of women are engaged in raising livestock and producing and managing agriculture. Women's time is constrained when there is scarcity of fuelwood, fodder, and water resources. Women maintain roles in reproduction, production, and community management. Women's work relies on natural resources. Family survival depends upon natural resources. The environment, women, and development are interrelated with each other. Conventional approaches to development relied on economic growth and poverty alleviation. The consequence was environmental degradation and resource depletion. Industrial, road, and technological development led to greater adverse effects on the environment. The 1987 Bruntland Commission Report offered a new perspective on protecting the environment and recognized women's role in preserving, managing, and developing natural resources.

[Pharmacology].

PubMed

González, José; Orero, Ana; Olmo, Vicente; Martínez, David; Prieto, José; Bahlsen, Jose Antonio; Zaragozá, Francisco; Honorato, Jesús

2011-06-01

Two of the main characteristics of western societies in the last fifty years have been the medicalization of the human life and the environmental degradation. The first one has forced human being to consider medicines use related to what would be rational, reasonable and well-reasoned. The second one brought us to a new ecologist conscience. In relation to the "human social system", the effects of medication can be considered very positive as a whole, particularly those related to the amazing increase of expectative and quality of life. But, along with those unquestionable beneficial effects, medicines have also caused some negative effects for other biotic and abiotic systems, such as microbian alterations and their undesirable consequences which have involved the massive use of antibiotics in medicine and veterinary, the uncontrolled elimination of millions of doses of all kind of drugs, additives and excipients, etc., as well as atmospheric contamination and degradation of forests and deep oceans which can have been caused by investigation and production of determinated drugs. In this context Pharmacology appears as a scientific discipline that studies the research (R), development (D), production (P), and utilization (U) of drugs and medical substances in relation to the environment. From a farmaecologic perspective the drugs utilization has its development in three main contexts, all of them closely related: prescription quality, farmaceutical care, and patient's active participation in his own disease and treatment.

pH-Dependent stability of azithromycin in aqueous solution and structure identification of two new degradation products.

PubMed

Saita, Maria Grazia; Aleo, Danilo; Melilli, Barbara; Mangiafico, Sergio; Cro, Melina; Sanfilippo, Claudia; Patti, Angela

2018-05-28

The degradation profile of azithromycin in buffered solutions was investigated using HPLC and found to be pH dependent in the range of 6.0-7.2. Desosaminylazitromycin, derived from hydrolytic loss of cladinose of the parent molecule, was the major degradation product at pH 6.0 but its amount progressively decreased moving toward pH 7.2. Two additional unreported degradation products were also observed and their structures were fully elucidated by MS- and NMR-spectroscopy to be associated with opening of the macrocyclic lactone ring. Copyright © 2018. Published by Elsevier B.V.

Difference analysis of the enzymatic hydrolysis performance of acid-catalyzed steam-exploded corn stover before and after washing with water.

PubMed

Zhu, Junjun; Shi, Linli; Zhang, Lingling; Xu, Yong; Yong, Qiang; Ouyang, Jia; Yu, Shiyuan

2016-10-01

The difference in the enzymatic hydrolysis yield of acid-catalyzed steam-exploded corn stover (ASC) before and after washing with water reached approximately 15 % under the same conditions. The reasons for the difference in the yield between ASC and washed ASC (wASC) were determined through the analysis of the composition of ASC prehydrolyzate and sugar concentration of enzymatic hydrolyzate. Salts produced by neutralization (CaSO4, Na2SO4, K2SO4, and (NH4)2SO4), sugars (polysaccharides, oligosaccharides, and monosaccharides), sugar-degradation products (weak acids and furans), and lignin-degradation products (ethyl acetate extracts and nine main lignin-degradation products) were back-added to wASC. Results showed that these products, except furans, exerted negative effect on enzymatic hydrolysis. According to the characteristics of acid-catalyzed steam explosion pretreatment, the five sugar-degradation products' mixture and salts [Na2SO4, (NH4)2SO4] showed minimal negative inhibition effect on enzymatic hydrolysis. By contrast, furans demonstrated a promotion effect. Moreover, soluble sugars, such as 13 g/L xylose (decreased by 6.38 %), 5 g/L cellobiose (5.36 %), 10 g/L glucose (3.67 %), as well as lignin-degradation products, and ethyl acetate extracts (4.87 %), exhibited evident inhibition effect on enzymatic hydrolysis. Therefore, removal of soluble sugars and lignin-degradation products could effectively promote the enzymatic hydrolysis performance.

Shape memory polyurethanes with oxidation-induced degradation: In vivo and in vitro correlations for endovascular material applications.

PubMed

Weems, Andrew C; Wacker, Kevin T; Carrow, James K; Boyle, Anthony J; Maitland, Duncan J

2017-09-01

The synthesis of thermoset shape memory polymer (SMP) polyurethanes from symmetric, aliphatic alcohols and diisocyanates has previously demonstrated excellent biocompatibility in short term in vitro and in vivo studies, although long term stability has not been investigated. Here we demonstrate that while rapid oxidation occurs in these thermoset SMPs, facilitated by the incorporation of multi-functional, branching amino groups, byproduct analysis does not indicate toxicological concern for these materials. Through complex multi-step chemical reactions, chain scission begins from the amines in the monomeric repeat units, and results, ultimately, in the formation of carboxylic acids, secondary and primary amines; the degradation rate and product concentrations were confirmed using liquid chromatography mass spectrometry, in model compound studies, yielding a previously unexamined degradation mechanism for these biomaterials. The rate of degradation is dependent on the hydrogen peroxide concentration, and comparison of explanted samples reveals a much slower rate in vivo compared to the widely accepted literature in vitro real-time equivalent of 3% H 2 O 2 . Cytotoxicity studies of the material surface, and examination of the degradation product accumulations, indicate that degradation has negligible impact on cytotoxicity of these materials. This paper presents an in-depth analysis on the degradation of porous, shape memory polyurethanes (SMPs), including traditional surface characterization as well as model degradation compounds with absolute quantification. This combination of techniques allows for determination of rates of degradation as well as accumulation of individual degradation products. These behaviors are used for in vivo-in vitro comparisons for determination of real time degradation rates. Previous studies have primarily been limited to surface characterization without examination of degradation products and accumulation rates. To our knowledge, our work presents a unique example where a range of material scales (atomistic-scale model compounds along with macroscopic porous SMPs) are used in conjunction with ex planted samples for calculation of degradation rates and toxicological risk. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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

NASA Technical Reports Server (NTRS)

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.

Bivariate versus multivariate smart spectrophotometric calibration methods for the simultaneous determination of a quaternary mixture of mosapride, pantoprazole and their degradation products.

PubMed

Hegazy, M A; Yehia, A M; Moustafa, A A

2013-05-01

The ability of bivariate and multivariate spectrophotometric methods was demonstrated in the resolution of a quaternary mixture of mosapride, pantoprazole and their degradation products. The bivariate calibrations include bivariate spectrophotometric method (BSM) and H-point standard addition method (HPSAM), which were able to determine the two drugs, simultaneously, but not in the presence of their degradation products, the results showed that simultaneous determinations could be performed in the concentration ranges of 5.0-50.0 microg/ml for mosapride and 10.0-40.0 microg/ml for pantoprazole by bivariate spectrophotometric method and in the concentration ranges of 5.0-45.0 microg/ml for both drugs by H-point standard addition method. Moreover, the applied multivariate calibration methods were able for the determination of mosapride, pantoprazole and their degradation products using concentration residuals augmented classical least squares (CRACLS) and partial least squares (PLS). The proposed multivariate methods were applied to 17 synthetic samples in the concentration ranges of 3.0-12.0 microg/ml mosapride, 8.0-32.0 microg/ml pantoprazole, 1.5-6.0 microg/ml mosapride degradation products and 2.0-8.0 microg/ml pantoprazole degradation products. The proposed bivariate and multivariate calibration methods were successfully applied to the determination of mosapride and pantoprazole in their pharmaceutical preparations.

Theoretical investigation on the kinetics and mechanisms of hydroxyl radical-induced transformation of parabens and its consequences for toxicity: Influence of alkyl-chain length.

PubMed

Gao, Yanpeng; Ji, Yuemeng; Li, Guiying; An, Taicheng

2016-03-15

As emerging organic contaminants (EOCs), the ubiquitous presence of preservative parabens in water causes a serious environmental concern. Hydroxyl radical ((•)OH) is a strong oxidant that can degrade EOCs through photochemistry in surface water environments as well as in advanced oxidation processes (AOPs). To better understand the degradation mechanisms, kinetics, and products toxicity of the preservative parabens in aquatic environments and AOPs, the (•)OH-initiated degradation reactions of the four parabens were investigated systematically using a computational approach. The four studied parabens with increase of alkyl-chain length were methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), and dibutylparaben (BPB). Results showed that the four parabens can be initially attacked by (•)OH through (•)OH-addition and H-abstraction routes. The (•)OH-addition route was more important for the degradation of shorter alkyl-chain parabens like MPB and EPB, while the H-abstraction route was predominant for the degradation of parabens with longer alkyl-chain for example PPB and BPB. In assessing the aquatic toxicity of parabens and their degradation products using the model calculations, the products of the (•)OH-addition route were found to be more toxic to green algae than original parabens. Although all degradation products were less toxic to daphnia and fish than corresponding parental parabens, they could be still harmful to these aquatic organisms. Furthermore, as alkyl-chain length increased, the ecotoxicity of parabens and their degradation products was found to be also increased. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of aqueous phase chemical warfare agent degradation products by negative mode ion mobility time-of-flight mass spectrometry [IM(tof)MS].

PubMed

Steiner, Wes E; Harden, Charles S; Hong, Feng; Klopsch, Steve J; Hill, Herbert H; McHugh, Vincent M

2006-02-01

The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined. Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified reference materials (CRM) of CWA degradation products for the detection of Schedule 1, 2, or 3 toxic chemicals or their precursors as defined by the chemical warfare convention (CWC) treaty verification were used in this study. A mixture of six G-series nerve related CWA degradation products (EMPA, IMPA, EHEP, IHEP, CHMPA, and PMPA) and their related collision induced dissociation (CID) fragment ions (MPA and EPA) were found in each case to be clearly resolved and detected using the IM(tof)MS instrument in negative ion monitoring mode. Corresponding ions, masses, drift times, K(o) values, and signal intensities for each of the CWA degradation products are reported.

Degradation of atrazine by microwave-assisted electrodeless discharge mercury lamp in aqueous solution.

PubMed

Ta, Na; Hong, Jun; Liu, Tingfeng; Sun, Cheng

2006-11-02

The present study investigates the degradation of atrazine (2-chloro-4-(ethyl amino)-6-isopropyl amino-s-triazine) in aqueous solution by a developed new method, namely by means of a microwave-assisted electrodeless discharge mercury lamp (MW-EDML). An experimental design was conducted to assess the influence of various parameters: pH value, initial concentration, amount of EDML, initial volume and coexisted solvent. Atrazine was degraded completely by EDML in a relatively short time (i.e. t(1/2)=1.2 min for 10 mg/l). Additionally, the identification of main degradation products during atrazine degradation process was conducted by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This study proposes the degradation mechanism including four possible pathways for atrazine degradation according to the degradation products.

Hydrothermal degradation of lignin: products analysis for phenol formaldehyde adhesive synthesis.

PubMed

Yang, Sheng; Yuan, Tong-Qi; Li, Ming-Fei; Sun, Run-Cang

2015-01-01

Corncob lignin was treated with pressurized hot water in a cylindrical autoclave in current investigation. With the aim of investigating the effect of reaction temperature and retention time on the distribution of degradation products, the products were divided into five fractions including gas, volatile organic compounds, water-soluble oil, heavy oil, and solid residue. It was found that hydrothermal degradation of corncob lignin in pressurized hot water produced a large amount of phenolic compounds with lower molecular weight than the raw lignin. Some phenolic and benzene derivatives monomers such as vanillin, 2-methoxy-phenol, 2-ethyl-phenol, p-xylene, and 1, 3-dimethyl-benzene were also identified in the degradation products. The products were further analyzed by GC-MS, GPC, 2D-HSQC, and (31)P-NMR to investigate their suitability for partial incorporation into phenol formaldehyde adhesive as a substitution of phenol. The results indicated that the reaction temperature had more effect on the products distribution than the retention time. The optimal condition for heavy oil production appeared at 290 °C with retention time 0 min. The compounds of heavy oil had more active sites than the raw lignin, suggesting that the heavy oil obtained from hydrothermal degradation of lignin is a promising material for phenol formaldehyde adhesive synthesis. Copyright © 2014 Elsevier B.V. All rights reserved.

Production of Insecticide Degradates in Juices: Implications for Risk Assessment.

PubMed

Radford, Samantha A; Panuwet, Parinya; Hunter, Ronald E; Barr, Dana Boyd; Ryan, P Barry

2016-06-08

This study was designed to observe the production of degradates of two organophosphorus insecticides and one pyrethroid insecticide in beverages. Purified water, white grape juice, apple juice, and red grape juice were fortified with 500 ng/g malathion, chlorpyrifos, and permethrin, and aliquots were extracted for malathion dicarboxylic acid (MDA), 3,5,6-trichloro-2-pyridinol (TCPy), and 3-phenoxybenzoic acid (3-PBA) several times over a 15 day period of being stored in the dark at 2.5 °C. Overall, first-order kinetics were observed for production of MDA, and statistically significant production of TCPy was also observed. Statistically significant production of 3-phenoxybenzoic acid was not observed. Results indicate that insecticides degrade in food and beverages, and this degradation may lead to preexisting insecticide metabolites in the beverages. Therefore, it is suggested that caution should be exercised when using urinary insecticide metabolites to assess exposure and risk.

Screening of nerve agent degradation products by MALDI-TOFMS.

PubMed

Shu, You-Ren; Su, An-Kai; Liu, Ju-Tsung; Lin, Cheng-Huang

2006-07-01

A novel method for the rapid screening of degradation products derived from nerve agents by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is described. Five standard products were selected as model compounds, including isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA), isobutyl methylphosphonic acid (i-BuMPA), and cyclohexyl methylphosphonic acid (CHMPA), which are degradation products of Sarin (GB), Soman (GD), VX, Russian VX (RVX), and GF, respectively. For comparison, CHCA (alpha-cyano-4-hydroxycinnamic acid) and DCCA (7-(diethylamino)coumarin-3-carboxylic acid) were used as the MALDI-matrix when the third harmonic generation (355 nm) of a Nd:YAG laser and a hydrogen Raman laser (multifrequency laser) were used, respectively. The method permitted the five nerve agent degradation products to be screened rapidly and successfully, suggesting that it has the potential for use as a routine monitoring tool.

Quantification of the Barkhausen noise method for the evaluation of time-dependent degradation

NASA Astrophysics Data System (ADS)

Kim, Dong-Won; Kwon, Dongil

2003-02-01

The Barkhausen noise (BN) method has long been applied to measure the bulk magnetic properties of magnetic materials. Recently, this important nondestructive testing (NDT) method has been applied to evaluate microstructure, stress distribution analysis, fatigue, creep and fracture characteristics. Until now the BN method has been used only qualitatively in evaluating the variation of BN with variations in material properties. For this reason, few NDT methods have been applied in industrial plants and laboratories. The present investigation studied the coercive force and BN while varying the microstructure of ultrafine-grained steels and SA508 cl.3 steels. This variation was carried out according to the second heat-treatment condition with rolling of ultrafine-grained steels and the simulated time-dependent degradation of SA 508 cl.3 steels. An attempt was also made to quantify BN from the relationship between the velocity of magnetic domain walls and the retarding force, using the coercive force of the domain wall movement. The microstructure variation was analyzed according to time-dependent degradation. Fracture toughness was evaluated quantitatively by measuring the BN from two intermediary parameters; grain size and distribution of nonmagnetic particles. From these measurements, the variation of microstructure and fracture toughness can be directly evaluated by the BN method as an accurate in situ NDT method.

Laboratory evaluation of oil spill bioremediation products in salt and freshwater systems.

PubMed

Haines, John R; Kleiner, Eric J; McClellan, Kim A; Koran, Karen M; Holder, Edith L; King, Dennis W; Venosa, Albert D

2005-05-01

Ten oil spill bioremediation products were tested in the laboratory for their ability to enhance biodegradation of weathered Alaskan North Slope crude oil in both freshwater and saltwater media. The products included nutrients to stimulate inoculated microorganisms, nutrients plus an oil-degrading inoculum, nutrients plus compounds intended to stimulate oil-degrading activity, or other compounds intended to enhance microbial activity. The product tests were undertaken to evaluate significant modifications in the existing official United States Environmental Protection Agency (EPA) protocol used for qualifying commercial bioremediation agents for use in oil spills. The EPA protocol was modified to include defined formulas for the exposure waters (freshwater, saltwater), a positive control using a known inoculum and nutrients, two negative controls (one sterile, the other inoculated but nutrient-limited), and simplified oil chemical analysis. Three analysts conducted the product test independently in each type of exposure water in round-robin fashion. Statistical tests were performed on analyst variability, reproducibility, and repeatability, and the performance of the various products was quantified in both exposure media. Analysis of variance showed that the analyst error at each time-point was highly significant (P values ranged from 0.0001 to 0.008, depending on water type and oil fraction). In the saltwater tests, six products demonstrated various degrees of biodegradative activity against the alkane fraction of the crude oil and three degraded the aromatic hydrocarbons by >10%. In the freshwater tests, eight products caused >20% loss of alkane hydrocarbons, of which five degraded the alkanes by >50%. Only four products were able to degrade polycyclic aromatic hydrocarbons (PAHs) by >20%, one of which caused 88% removal. However, when the variability of the analysts was taken into consideration, only one of the ten products was found to yield significant percent removals of the PAH fraction and only in freshwater. Viable microorganism population analysis (most-probable-number method) was also performed on every sample by each operator to measure the changes in aromatic and alkane hydrocarbon-degrading organism numbers. In general, little evidence of significant growth of either alkane- or PAH-degraders occurred among any of the ten products in either the saltwater or freshwater testing.

Transport and attenuation of chloroacetanilides in an agricultural headwater catchment

NASA Astrophysics Data System (ADS)

Lefrancq, Marie; Imfeld, Gwenaël; Millet, Maurice; Payraudeau, Sylvain

2015-04-01

Chloroacetanilides (e.g., S-metolachlor and acetochlor) are pre-emergent herbicides used on corn and sugar beet and are applied to bare soil, which is prone to runoff and erosion. Some of these herbicides are chiral and the commercial products can be isomerically enriched in the enantiomer-S compared to the enantiomer-R as an example S-metolachlor 80/20% S to R . Determination of the transport of these herbicides in the dissolved and particulate phases of runoff water and degradation in agricultural catchments is currently lacking. The objectives of this study were i) to quantify over an corn growing season the export of chloroacetanilides and their main degradation products (ethane sulfonic (ESA) and oxanilic acid (OXA) degradates of metolachlor (MESA and MOXA) and acetochlor (AcESA and AcOXA)) in an 47 ha agricultural head-catchment in the dissolved and particulate phases, and ii) to evaluate S-metolachlor biodegradation from its application on the field to its export from the catchment using enantiomer analysis. Runoff, erosion, hydrochemistry and chloroacetanilide transport were evaluated at both the plot and catchment scales. Our results showed that an important amount of the pesticide load is missed when only the dissolved concentration of the parent compound is analysed. The total export coefficients for S-metolachlor and acetochlor and their degradation products were 11.4 and 11.8%, respectively, which includes both the dissolved and particulate loads. The partitioning of S-metolachlor and acetochlor between the dissolved and particulate phases varied widely over time and was linked to the suspended solid concentrations. Detection of S-metolachlor degradation products in runoff water was more frequent compared to that of acetochlor degradation products. Enrichment up to 37% of R-metolachlor was observed during the corn growing season, supporting enantioselective degradation of S-metolachlor. Our field study indicates the potential of enantiomer analyses for assessing chloroacetanilide biodegradation and could be complemented with laboratory benchmark studies on enantiomeric fractionation during chloroacetanilide degradation combined with an analysis of the degradation products to evaluate the extent of biodegradation in agro-ecosystems. We anticipate that our results will be a starting point for better understanding and predicting transport and degradation of chloroacetanilides at the agricultural catchment scale.

Rubber gloves biodegradation by a consortium, mixed culture and pure culture isolated from soil samples.

PubMed

Nawong, Chairat; Umsakul, Kamontam; Sermwittayawong, Natthawan

2018-02-03

An increasing production of natural rubber (NR) products has led to major challenges in waste management. In this study, the degradation of rubber latex gloves in a mineral salt medium (MSM) using a bacterial consortium, a mixed culture of the selected bacteria and a pure culture were studied. The highest 18% weight loss of the rubber gloves were detected after incubated with the mixed culture. The increased viable cell counts over incubation time indicated that cells used rubber gloves as sole carbon source leading to the degradation of the polymer. The growth behavior of NR-degrading bacteria on the latex gloves surface was investigated using the scanning electron microscope (SEM). The occurrence of the aldehyde groups in the degradation products was observed by Fourier Transform Infrared Spectroscopy analysis. Rhodococcus pyridinivorans strain F5 gave the highest weight loss of rubber gloves among the isolated strain and posses latex clearing protein encoded by lcp gene. The mixed culture of the selected strains showed the potential in degrading rubber within 30 days and is considered to be used efficiently for rubber product degradation. This is the first report to demonstrate a strong ability to degrade rubber by Rhodococcus pyridinivorans. Copyright © 2018. Published by Elsevier Editora Ltda.

Biodegradation of high molecular weight lignin under sulfate reducing conditions: lignin degradability and degradation by-products.

PubMed

Ko, Jae-Jung; Shimizu, Yoshihisa; Ikeda, Kazuhiro; Kim, Seog-Ku; Park, Chul-Hwi; Matsui, Saburo

2009-02-01

This study is designed to investigate the biodegradation of high molecular weight (HMW) lignin under sulfate reducing conditions. With a continuously mesophilic operated reactor in the presence of co-substrates of cellulose, the changes in HMW lignin concentration and chemical structure were analyzed. The acid precipitable polymeric lignin (APPL) and lignin monomers, which are known as degradation by-products, were isolated and detected. The results showed that HMW lignin decreased and showed a maximum degradation capacity of 3.49 mg/l/day. APPL was confirmed as a polymeric degradation by-product and was accumulated in accordance with HMW lignin reduction. We also observed non-linear accumulation of aromatic lignin monomers such as hydrocinnamic acid. Through our experimental results, it was determined that HMW lignin, when provided with a co-substrate of cellulose, is biodegraded through production of APPL and aromatic monomers under anaerobic sulfate reducing conditions with a co-substrate of cellulose.

In Situ Monitoring the Uptake of Moisture into Hybrid Perovskite Thin Films.

PubMed

Schlipf, Johannes; Bießmann, Lorenz; Oesinghaus, Lukas; Berger, Edith; Metwalli, Ezzeldin; Lercher, Johannes A; Porcar, Lionel; Müller-Buschbaum, Peter

2018-04-19

Solution-processed hybrid perovskites are of great interest for use in photovoltaics. However, polycrystalline perovskite thin films show strong degradation in humid atmospheres, which poses an important challenge for large-scale market introduction. With in situ grazing incidence neutron scattering (GISANS) we analyzed water content, degradation products, and morphological changes during prolonged exposure to several humidity levels. In high humidity, the formation of metastable hydrate phases is accompanied by domain swelling, which transforms the faceted crystals to a round-washed, pebble-like form. The films incorporate much more water than is integrated into the hydrates, with smaller crystals being more affected, making the degradation strongly dependent on film morphology. Even at low humidity, water is adsorbed on the crystal surfaces without the formation of crystalline degradation products. Thus, although production in an ambient atmosphere is of interest for industrial production it might lead to long-term degradation without appropriate countermeasures like postproduction drying below 30% RH.

Stochastic Modeling and Analysis of Multiple Nonlinear Accelerated Degradation Processes through Information Fusion

PubMed Central

Sun, Fuqiang; Liu, Le; Li, Xiaoyang; Liao, Haitao

2016-01-01

Accelerated degradation testing (ADT) is an efficient technique for evaluating the lifetime of a highly reliable product whose underlying failure process may be traced by the degradation of the product’s performance parameters with time. However, most research on ADT mainly focuses on a single performance parameter. In reality, the performance of a modern product is usually characterized by multiple parameters, and the degradation paths are usually nonlinear. To address such problems, this paper develops a new s-dependent nonlinear ADT model for products with multiple performance parameters using a general Wiener process and copulas. The general Wiener process models the nonlinear ADT data, and the dependency among different degradation measures is analyzed using the copula method. An engineering case study on a tuner’s ADT data is conducted to demonstrate the effectiveness of the proposed method. The results illustrate that the proposed method is quite effective in estimating the lifetime of a product with s-dependent performance parameters. PMID:27509499

Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product

NASA Astrophysics Data System (ADS)

Tantawy, Mahmoud A.; El-Ragehy, Nariman A.; Hassan, Nagiba Y.; Abdelkawy, Mohamed

2016-04-01

Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D1), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.

Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product.

PubMed

Tantawy, Mahmoud A; El-Ragehy, Nariman A; Hassan, Nagiba Y; Abdelkawy, Mohamed

2016-04-15

Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D(1)), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form. Copyright © 2016 Elsevier B.V. All rights reserved.

Products of hexachlorocyclopentadiene (C-56) in aqueous solution

USGS Publications Warehouse

Chou, S.-F.J.; Griffin, R.A.; Chou, I.-Ming; Larson, R.A.

1987-01-01

The photodegradation and degradation products of hexachlorocyclopentadiene (C-56) in aqueous solutions were studied in the laboratory. In each case, the half-life of C-56 was less than 4 min when exposed to sunlight. At least eight degradation products were positively or tentatively identified: 2,3,4,4,5-Pentachloro-2-cyclopentenone, hexachloro-2-cyclopentenone and hexachloro-3-cyclopentenone were the primary photodegradation products, and pentachlorocis-2,4-pentadienoic acid, Z- and E-pentachlorobutadiene and tetrachlorobutyne were the secondary degradation products. Dissociation of the primary photolysis products may proceed through corresponding pentadienoic acids to form smaller molecular weight compounds such as pentachlorobutadiene isomers and tetrachlorobutyne. In addition, dimerization of 2,3,4,4,5-pentachloro-2-cyclopentenone to form higher molecular weight compounds such as hexachloroindenone may present a minor route of degradation. The results also indicate that C-56 is highly photoreactive and suggest a possible pathway for the compound's transformation in the environment when exposed to sunlight. ?? 1987.

Nitenpyram degradation in finished drinking water.

PubMed

Noestheden, Matthew; Roberts, Simon; Hao, Chunyan

2016-07-15

Neonicotinoid pesticides and their metabolites have been indicated as contributing factors in the decline of honey bee colonies. A thorough understanding of neonicotinoid toxicity requires knowledge of their metabolites and environmental breakdown products. This work investigated the rapid degradation of the neonicotinoid nitenpyram in finished drinking water. Nitenpyram reaction products were characterized using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOFMS). A software algorithm that compared degraded and control samples was utilized to facilitate efficient data reduction. Fragmentation pathways for six reaction products and nitenpyram were proposed using predictive software and manual product ion analysis. This study showed that nitenpyram degradation in unpreserved finished drinking water was likely the result of oxidation, hydrolysis and reaction with Cl2 . Structures for six nitenpyram reaction products were proposed that suggest the C9/C11 olefin as the key reactive site. Similarities between the identified nitenpyram reaction products and imidacloprid metabolites highlight the importance of this study, as the toxicity of neonicotinoids to pollinators has been linked to their metabolites. Based on the proposed reaction mechanisms, the identified nitenpyram reaction products in finished drinking water could also be present in the environment and water treatment facilities. As such, identifying these degradation products will aid in evaluating the environmental impact of neonicotinoid pesticides. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Stability indicating methods for the analysis of cefprozil in the presence of its alkaline induced degradation product

NASA Astrophysics Data System (ADS)

Attia, Khalid A. M.; Nassar, Mohammed W. I.; El-Zeiny, Mohamed B.; Serag, Ahmed

2016-04-01

Three simple, specific, accurate and precise spectrophotometric methods were developed for the determination of cefprozil (CZ) in the presence of its alkaline induced degradation product (DCZ). The first method was the bivariate method, while the two other multivariate methods were partial least squares (PLS) and spectral residual augmented classical least squares (SRACLS). The multivariate methods were applied with and without variable selection procedure (genetic algorithm GA). These methods were tested by analyzing laboratory prepared mixtures of the above drug with its alkaline induced degradation product and they were applied to its commercial pharmaceutical products.

[The structure and antimicrobial activity of the partial degradation products of the antibiotic eremomycin].

PubMed

Berdnikova, T F; Lomakina, N N; Olsuf'eva, E N; Aleksandrova, L G; Potapova, N P; Rozynov, B V; Malkova, I V; Orlova, G I

1991-06-01

Antimicrobial activity of partial degradation products of eremomycin, a new glycopeptide antibiotic, was studied. The products formed by eremomycin deglycosylation (deseremosaminyl eremomycin, eremosaminyl aglycone and aglycone) and elimination of the chlorine atom from the molecule aglycone moiety (dechloroeremomycin). The spectral data in favour of the compounds structure are presented. It was found that partial degradation led to a decrease in the antimicrobial activity of the antibiotic. Dechloreremomycin had the highest activity among the products. Its MIC for the methicillin-resistant strains of Staphylococcus aureus was only twice as low as that of the initial antibiotic.

Acid-degradable polyurethane particles for protein-based vaccines

PubMed Central

Bachelder, Eric M.; Beaudette, Tristan T.; Broaders, Kyle E.; Paramonov, Sergey E.; Dashe, Jesse; Fréchet, Jean M. J.

2009-01-01

Acid-degradable particles containing a model protein antigen, ovalbumin, were prepared from a polyurethane with acetal moieties embedded throughout the polymer, and characterized by dynamic light scattering and transmission electron microscopy. The small molecule degradation by-product of the particles was synthesized and tested in vitro for toxicity indicating an LC50 of 12,500 μg/ml. A new liquid chromatography-mass spectrometry technique was developed to monitor the in vitro degradation of these particles. The degradation by-product inside RAW macrophages was at its highest level after 24 hours of culture and was efficiently exocytosed until it was no longer detectable after four days. When tested in vitro, these particles induced a substantial increase in the presentation of the immunodominant ovalbumin-derived peptide SIINFEKL in both macrophages and dendritic cells. In addition, vaccination with these particles generated a cytotoxic T-lymphocyte response that was superior to both free ovalbumin and particles made from an analogous but slower-degrading acid-labile polyurethane polymer. Overall, we present a fully degradable polymer system with non-toxic by-products, which may find use in various biomedical applications including protein-based vaccines. PMID:18710254

Hydrolytic degradation of alkaline lignin in hot-compressed water and ethanol.

PubMed

Yuan, Zhongshun; Cheng, Shuna; Leitch, Mathew; Xu, Chunbao Charles

2010-12-01

Alkaline lignin of a very high molecular weight was successfully degraded into oligomers in a hot-compressed water-ethanol medium with NaOH as the catalyst and phenol as the capping agent at 220-300 degrees C. Under the optimal reaction conditions, i.e., 260 degrees C, 1 h, with the lignin/phenol ratio of 1:1 (w/w), almost complete degradation was achieved, producing <1% solid residue and negligible gas products. The obtained degraded lignin had a number-average molecular weight M(n) and weight-average molecular weight M(w) of 450 and 1000 g/mol respectively, significantly lower than the M(n) and M(w) of 10,000 and 60,000 g/mol of the original lignin. A higher temperature and a longer reaction time favoured phenol combination, but increased the formation of solid residue due to the condensation reactions of the degradation intermediates/products. The degraded lignin products were soluble in organic solvents (such as THF), and were characterized by HPLC/GPC, IR and NMR. A possible mechanism for lignin hydrolytic degradation was also proposed in this study. 2010 Elsevier Ltd. All rights reserved.

Optimization of liquid-state fermentation conditions for the glyphosate degradation enzyme production of strain Aspergillus oryzae by ultraviolet mutagenesis.

PubMed

Fu, Gui-Ming; Li, Ru-Yi; Li, Kai-Min; Hu, Ming; Yuan, Xiao-Qiang; Li, Bin; Wang, Feng-Xue; Liu, Cheng-Mei; Wan, Yin

2016-11-16

This study aimed to obtain strains with high glyphosate-degrading ability and improve the ability of glyphosate degradation enzyme by the optimization of fermentation conditions. Spore from Aspergillus oryzae A-F02 was subjected to ultraviolet mutagenesis. Single-factor experiment and response surface methodology were used to optimize glyphosate degradation enzyme production from mutant strain by liquid-state fermentation. Four mutant strains were obtained and named as FUJX 001, FUJX 002, FUJX 003, and FUJX 004, in which FUJX 001 gave the highest total enzyme activity. Starch concentration at 0.56%, GP concentration at 1,370 mg/l, initial pH at 6.8, and temperature at 30°C were the optimum conditions for the improved glyphosate degradation endoenzyme production of A. oryzae FUJX 001. Under these conditions, the experimental endoenzyme activity was 784.15 U/100 ml fermentation liquor. The result (784.15 U/100 ml fermentation liquor) was approximately 14-fold higher than that of the original strain. The result highlights the potential of glyphosate degradation enzyme to degrade glyphosate.

Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries: Distribution, transport and fate

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.; ,

1992-01-01

The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6'-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be < 2% of the annual application of each herbicide in the Midwest.The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2???,6???-diethylacetanilide, 2-hydroxy-2???,6???-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be <2% of the annual application of each herbicide in the Midwest.

Degradation of Lignin by Cyathus Species

PubMed Central

Abbott, Thomas P.; Wicklow, Donald T.

1984-01-01

The ability of 12 Cyathus species to degrade 14C-labeled lignin in kenaf was studied. The sum of 14C released into solution plus 14C released into the gas phase over a 32-day fermentation period was used to determine average daily rates of lignin biodegradation. Cyathus pallidus. C. africanus, and C. berkeleyanus delignified kenaf most rapidly. C. canna showed the greatest preference for lignin degradation over other plant components, and its rate of lignin degradation was only slightly lower than the three most active species. The apparent ability of fungi to metabolize low-molecular-weight lignin breakdown products correlated well with their overall delignification rates. C. stercoreus metabolized degradation products of lignin from wheat straw better than those from kenaf lignin, based on the amount of low-molecular-weight products left in solution. PMID:16346497

Effects of oxygen and redox oscillation on degradation of cell-associated lipids in surficial marine sediments

NASA Astrophysics Data System (ADS)

Sun, Ming-Y. i.; Aller, Robert C.; Lee, Cindy; Wakeham, Stuart G.

2002-06-01

Degradation patterns of sedimentary algal lipids were tracked with time under variable redox treatments designed to mimic conditions in organic-rich, bioturbated deposits. Uniformly 13C-labeled algae were mixed with Long Island Sound surface muddy sediments and exposed to different redox regimes, including continuously oxic and anoxic, and oscillated oxic: anoxic conditions. Concentrations of several 13C-labeled algal fatty acids (16:1, 16:0 and 18:1), phytol and an alkene were measured serially. Results showed a large difference (∼10×) in first-order degradation rate constants of cell-associated lipids between continuously oxic and anoxic conditions. Exposure to oxic conditions increased the degradation of cell-associated lipids, and degradation rate constants were positive functions (linear or nonlinear) of the fraction of time sediments were oxic. Production of two new 13C-labeled compounds (iso-15:0 fatty acid and hexadecanol) further indicated that redox conditions and oxic: anoxic oscillations strongly affect microbial degradation of algal lipids and net synthesis of bacterial biomass. Production of 13C-labeled iso-15:0 fatty acid (a bacterial biomarker) was inversely proportional to the fraction of time sediments were oxic, rapidly decreasing after 10 days of incubation under oxic and frequently oscillated conditions. Turnover of bacterial biomass was faster under continuously or occasionally oxic conditions than under continuously anoxic conditions. 13C-labeled hexadecanol, an intermediate degradation product, accumulated under anoxic conditions but not under oxic or periodically oxic conditions. The frequency of oxic: anoxic oscillation clearly alters both the rate and pathways of lipid degradation in surficial sediments. Terminal degradation efficiency and lipid products from degradation of algal material depend on specific patterns of redox fluctuations.

Hotspots of human-induced biomass productivity decline and their social-ecological types toward supporting national policy and local studies on combating land degradation

NASA Astrophysics Data System (ADS)

Vu, Quyet Manh; Le, Quang Bao; Vlek, Paul L. G.

2014-10-01

Identification and social-ecological characterization of areas that experience high levels of persistent productivity decline are essential for planning appropriate management measures. Although land degradation is mainly induced by human actions, the phenomenon is concurrently influenced by global climate changes that need to be taken into account in land degradation assessments. This study aims to delineate the geographic hotspots of human-induced land degradation in the country and classify the social-ecological characterizations of each specific degradation hotspot type. The research entailed a long-term time-series (1982-2006) of Normalized Difference Vegetation Index to specify the extents of areas with significant biomass decline or increase in Vietnam. Annual rainfall and temperature time-series were then used to separate areas of human-induced biomass productivity decline from those driven by climate dynamics. Next, spatial cluster analyses identified social-ecological types of degradation for guiding further investigations at regional and local scales. The results show that about 19% of the national land mass experienced persistent declines in biomass productivity over the last 25 years. Most of the degraded areas are found in the Southeast and Mekong River Delta (17,984 km2), Northwest Mountains (14,336 km2), and Central Highlands (13,504 km2). We identified six and five social-ecological types of degradation hotspots in agricultural and forested zones, respectively. Constraints in soil nutrient availability and nutrient retention capability are widely spreading in all degradation hotspot types. These hotspot types are different from each other in social and ecological conditions, suggesting that region-specific strategies are needed for the formulation of land degradation combating policy.

Perception of force and stiffness in the presence of low-frequency haptic noise

PubMed Central

Gurari, Netta; Okamura, Allison M.; Kuchenbecker, Katherine J.

2017-01-01

Objective This work lays the foundation for future research on quantitative modeling of human stiffness perception. Our goal was to develop a method by which a human’s ability to perceive suprathreshold haptic force stimuli and haptic stiffness stimuli can be affected by adding haptic noise. Methods Five human participants performed a same-different task with a one-degree-of-freedom force-feedback device. Participants used the right index finger to actively interact with variations of force (∼5 and ∼8 N) and stiffness (∼290 N/m) stimuli that included one of four scaled amounts of haptically rendered noise (None, Low, Medium, High). The haptic noise was zero-mean Gaussian white noise that was low-pass filtered with a 2 Hz cut-off frequency; the resulting low-frequency signal was added to the force rendered while the participant interacted with the force and stiffness stimuli. Results We found that the precision with which participants could identify the magnitude of both the force and stiffness stimuli was affected by the magnitude of the low-frequency haptically rendered noise added to the haptic stimulus, as well as the magnitude of the haptic stimulus itself. The Weber fraction strongly correlated with the standard deviation of the low-frequency haptic noise with a Pearson product-moment correlation coefficient of ρ > 0.83. The mean standard deviation of the low-frequency haptic noise in the haptic stimuli ranged from 0.184 N to 1.111 N across the four haptically rendered noise levels, and the corresponding mean Weber fractions spanned between 0.042 and 0.101. Conclusions The human ability to perceive both suprathreshold haptic force and stiffness stimuli degrades in the presence of added low-frequency haptic noise. Future work can use the reported methods to investigate how force perception and stiffness perception may relate, with possible applications in haptic watermarking and in the assessment of the functionality of peripheral pathways in individuals with haptic impairments. PMID:28575068

Stability behaviour of antiretroviral drugs and their combinations. 5: Characterization of novel degradation products of abacavir sulfate by mass and nuclear magnetic resonance spectrometry.

PubMed

Kurmi, Moolchand; Sahu, Archana; Singh, Saranjit

2017-02-05

In the present study, degradation behaviour of abacavir sulfate was evaluated in solution and solid stress conditions. Solution state studies resulted in formation of eleven degradation products; of which two were also formed on solid stress. The same were separated by high performance liquid chromatography. They were characterized using liquid chromatography-high resolution mass spectrometry, liquid chromatography-multistage mass spectrometry and hydrogen/deuterium exchange mass spectrometry data. Additionally, seven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance studies for their structural confirmation. Copyright © 2016 Elsevier B.V. All rights reserved.

Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya

NASA Astrophysics Data System (ADS)

Mganga, K. Z.; Musimba, N. K. R.; Nyariki, D. M.

2015-12-01

Drylands occupy more than 80 % of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya.

PubMed

Mganga, K Z; Musimba, N K R; Nyariki, D M

2015-12-01

Drylands occupy more than 80% of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

Current-use and organochlorine pesticides and polychlorinated biphenyls in the biodegradable fraction of source separated household waste, compost, and anaerobic digest.

PubMed

Hellström, Anna; Nilsson, Marie-Louise; Kylin, Henrik

2011-01-01

Several current-use (≤ 80 ng g⁻¹ dry weight) and organochlorine pesticides (≤ 15 ng g⁻¹ dry weight) and polychlorinated biphenyls (≤ 18 ng g⁻¹ dry weight) were found in the biodegradable fraction of source separated household waste, compost, and/or anaerobic digestate. The degradation rates of individual compounds differ depending on the treatment. Dieldrin and pentachloroaniline, e.g., degrade more rapidly than the waste is mineralized and accumulates in the products after all treatments. Many organochlorines degrade at the same rate as the waste and have the same concentrations in the waste and products. Chlorpyrifos degrades slower than the waste and accumulates in all products and ethion during anaerobic digestion. The polychlorinated biphenyls and some pesticides show different degradations rates relative the waste during different processes. Understanding the degradation of the contaminants under different conditions is necessary to develop quality criteria for the use of compost and digest.

Unmanned Aircraft Systems Roadmap, 2005-2030

DTIC Science & Technology

2005-01-01

directly addresses the dangerous mission of attacking or degrading integrated air defense systems. The attributes that make the use of unmanned...meter of reinforced concrete covered by one meter of soil . The Air Force hopes to deploy it by 2007 on the F-15E, followed by deployment on several... degradation from repeated analog-digital-analog conversions. For this reason, multispectral versions of digital focal arrays are critical. Additionally

Kinetics of methane production and biodegradation of linear alkylbenzene sulfonate from laundry wastewater.

PubMed

Motteran, Fabrício; Braga, Juliana K; Silva, Edson L; Varesche, Maria Bernadete A

2016-12-05

This study evaluates the kinetics of methane production and degradation of standard linear alkylbenzene sulfonate (LAS) (50 ± 3.5 mg/L) and LAS from laundry wastewater (85 ± 2.1 mg/L) in anaerobic batch reactors at 30°C with different sources of inoculum. The inocula were obtained by auto-fermentation (AFM) and UASB reactors from wastewater treatment of poultry slaughterhouse (SGH), swine production (SWT) and wastewater treatment thermophilic of sugarcane industry (THR). The study was divided into three phases: synthetic substrate (Phase I), standard LAS (Phase II) and LAS from laundry wastewater (Phase III). For SGH, the highest values for cumulative methane productions (1,844.8 ± 149 µmol-Phase II), methane production rate (70.8 ± 88 µmol/h-Phase II and 4.01 ± 07 µmol/h-Phase III) were observed. The use of thermophilic biomass (THR) incubated at 30°C was not favorable for methane production and LAS biodegradation, but the highest kinetic coefficient degradation (k 1 app ) was obtained for LAS (0.33 ± 0.3 h) compared with mesophilic biomass (SGH and SWT) (0.13 ± 0.02 h). Therefore, both LAS sources influenced the kinetics of methane production and organic matter degradation. For SGH, inoculum obtained the highest LAS degradation. In the SGH inoculum sequenced by MiSeq-Illumina was identified genera (VadinCA02, Candidatus Cloacamonas, VadinHB04, PD-UASB-13) related to degrade toxic compounds. Therefore, it recommended the reactor mesophilic inoculum UASB (SGH) for the LAS degradation.

Bacterial secondary production on vascular plant detritus: relationships to detritus composition and degradation rate.

PubMed Central

Moran, M A; Hodson, R E

1989-01-01

Bacterial production at the expense of vascular plant detritus was measured for three emergent plant species (Juncus effusus, Panicum hemitomon, and Typha latifolia) degrading in the littoral zone of a thermally impacted lake. Bacterial secondary production, measured as tritiated thymidine incorporation into DNA, ranged from 0.01 to 0.81 microgram of bacterial C mg of detritus-1 day-1. The three plant species differed with respect to the amount of bacterial productivity they supported per milligram of detritus, in accordance with the predicted biodegradability of the plant material based on initial nitrogen content, lignin content, and C/N ratio. Bacterial production also varied throughout the 22 weeks of in situ decomposition and was positively related to the nitrogen content and lignin content of the remaining detritus, as well as to the temperature of the lake water. Over time, production was negatively related to the C/N ratio and cellulose content of the degrading plant material. Bacterial production on degrading plant material was also calculated on the basis of plant surface area and ranged from 0.17 to 1.98 micrograms of bacterial C cm-2 day-1. Surface area-based calculations did not correlate well with either initial plant composition or changing composition of the remaining detritus during decomposition. The rate of bacterial detritus degradation, calculated from measured production of surface-attached bacteria, was much lower than the actual rate of weight loss of plant material. This discrepancy may be attributable to the importance of nonbacterial organisms in the degradation and loss of plant material from litterbags or to the microbially mediated solubilization of particulate material prior to bacterial utilization, or both. PMID:2802603

Degradation of chloroacetanilide herbicides by anodic fenton treatment.

PubMed

Friedman, Carey L; Lemley, Ann T; Hay, Anthony

2006-04-05

Anodic Fenton treatment (AFT) is an electrochemical treatment employing the Fenton reaction for the generation of hydroxyl radicals, strong oxidants that can degrade organic compounds via hydrogen abstraction. AFT has potential use for the remediation of aqueous pesticide waste. The degradation rates of chloroacetanilides by AFT were investigated in this work, which demonstrates that AFT can be used to rapidly and completely remove chloroacetanilide herbicides from aqueous solutions. Acetochlor, alachlor, butachlor, metolachlor, and propachlor were treated by AFT, and parent compound concentrations were analyzed over the course of the treatment time. Degradation curves were plotted and fitted by the AFT kinetic model for each herbicide, and AFT model kinetic parameters were used to calculate degradation rate constants. The reactivity order of these five active ingredients toward hydroxyl radical was acetochlor approximately metolachlor > butachlor approximately alachlor > propachlor. Treatment of the chloroacetanilides by AFT removed the parent compounds but did not completely mineralize them. However, AFT did result in an increase in the biodegradability of chloroacetanilide aqueous solutions, as evidenced by an increase in the 5-day biochemical oxygen demand to chemical oxygen demand ratio (BOD5/COD) to >0.3, indicating completely biodegradable solutions. Several degradation products were formed and subsequently degraded, although not always completely. Some of these were identified by mass spectral analyses. Among the products, isomers of phenolic and carbonyl derivatives of parent compounds were common to each of the herbicides analyzed. More extensively oxidized products were not detected. Degradation pathways are proposed for each of the parent compounds and identified products.

High-performance liquid chromatography/high-resolution multiple stage tandem mass spectrometry using negative-ion-mode hydroxide-doped electrospray ionization for the characterization of lignin degradation products.

PubMed

Owen, Benjamin C; Haupert, Laura J; Jarrell, Tiffany M; Marcum, Christopher L; Parsell, Trenton H; Abu-Omar, Mahdi M; Bozell, Joseph J; Black, Stuart K; Kenttämaa, Hilkka I

2012-07-17

In the search for a replacement for fossil fuel and the valuable chemicals currently obtained from crude oil, lignocellulosic biomass has become a promising candidate as an alternative biorenewable source for crude oil. Hence, many research efforts focus on the extraction, degradation, and catalytic transformation of lignin, hemicellulose, and cellulose. Unfortunately, these processes result in the production of very complex mixtures. Further, while methods have been developed for the analysis of mixtures of oligosaccharides, this is not true for the complex mixtures generated upon degradation of lignin. For example, high-performance liquid chromatography/multiple stage tandem mass spectrometry (HPLC/MS(n)), a tool proven to be invaluable in the analysis of complex mixtures derived from many other biopolymers, such as proteins and DNA, has not been implemented for lignin degradation products. In this study, we have developed an HPLC separation method for lignin degradation products that is amenable to negative-ion-mode electrospray ionization (ESI doped with NaOH), the best method identified thus far for ionization of lignin-related model compounds without fragmentation. The separated and ionized compounds are then analyzed by MS(3) experiments to obtain detailed structural information while simultaneously performing high-resolution measurements to determine their elemental compositions in the two parts of a commercial linear quadrupole ion trap/Fourier-transform ion cyclotron resonance mass spectrometer. A lignin degradation product mixture was analyzed using this method, and molecular structures were proposed for some components. This methodology significantly improves the ability to analyze complex product mixtures that result from degraded lignin.

Modeling of competitive mutualistic relationships. Application to cellulose degradation by Streptomyces sp. strains.

PubMed

Thierie, Jacques; Penninckx, Michel J

2007-12-01

A "cascade" model depicts microbial degradation of a complex nutrient/substrate through a succession of intermediate compounds. Each stage is characterized by a particular species producing a typical degradation enzyme induced by its own degradation product. The final compound of the cascade consists of a single assimilable substrate used by all species. This results in a competition situation, whereas the contribution of all strains to the production of a complete set of efficient enzymes generates a mutualistic relationship. The model was shown to be appropriate to describe degradation of cellulose by a consortium of Streptomyces sp. strains. The simplicity and the model capacity for generalization are promising and could be used for various degradation processes both at laboratory and environmental scales.

In-Process Atomic-Force Microscopy (AFM) Based Inspection

PubMed Central

Mekid, Samir

2017-01-01

A new in-process atomic-force microscopy (AFM) based inspection is presented for nanolithography to compensate for any deviation such as instantaneous degradation of the lithography probe tip. Traditional method used the AFM probes for lithography work and retract to inspect the obtained feature but this practice degrades the probe tip shape and hence, affects the measurement quality. This paper suggests a second dedicated lithography probe that is positioned back-to-back to the AFM probe under two synchronized controllers to correct any deviation in the process compared to specifications. This method shows that the quality improvement of the nanomachining, in progress probe tip wear, and better understanding of nanomachining. The system is hosted in a recently developed nanomanipulator for educational and research purposes. PMID:28561747

Methods of saccharification of polysaccharides in plants

DOEpatents

Howard, John; Fake, Gina

2014-04-29

Saccharification of polysaccharides of plants is provided, where release of fermentable sugars from cellulose is obtained by adding plant tissue composition. Production of glucose is obtained without the need to add additional .beta.-glucosidase. Adding plant tissue composition to a process using a cellulose degrading composition to degrade cellulose results in an increase in the production of fermentable sugars compared to a process in which plant tissue composition is not added. Using plant tissue composition in a process using a cellulose degrading enzyme composition to degrade cellulose results in decrease in the amount of cellulose degrading enzyme composition or exogenously applied cellulase required to produce fermentable sugars.

Restoring and Enhancing Productivity of Degraded Tephra-Derived Soils

Treesearch

Chuck Bulmer; Jim Archuleta; Mike Curran

2007-01-01

Soil restoration (sometimes termed enhancement) is an important strategy for sustaining the productivity of managed forest landscapes. Tephra-derived soils have unique physical and chemical characteristics that affect their response to disturbance and restoration. A variety of factors reduce forest productivity on degraded soils. Site-specific information on soil...

Calcium leaching behavior of cementitious materials in hydrochloric acid solution.

PubMed

Yang, Huashan; Che, Yujun; Leng, Faguang

2018-06-11

The calcium leaching behavior of cement paste and silica fume modified calcium hydroxide paste, exposed to hydrochloric acid solution, is reported in this paper. The kinetic of degradation was assessed by the changes of pH of hydrochloric acid solution with time. The changes of compressive strength of specimens in hydrochloric acid with time were tested. Hydration products of leached specimens were also analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG), and atomic force microscope (AFM). Tests results show that there is a dynamic equilibrium in the supply and consumption of calcium hydroxide in hydrochloric acid solution, which govern the stability of hydration products such as calcium silicate hydrate (C-S-H). The decrease of compressive strength indicates that C-S-H are decomposed due to the lower concentration of calcium hydroxide in the pore solution than the equilibrium concentration of the hydration products. Furthermore, the hydration of unhydrated clinker delayed the decomposition of C-S-H in hydrochloric acid solution due to the increase of calcium hydroxide in pore solution of cementitious materials.

Requirement for serum in medium supplemented with insulin-transferrin-selenium for hydrodynamic cultivation of engineered cartilage.

PubMed

Yang, Yueh-Hsun; Barabino, Gilda A

2011-08-01

Achievement of viable engineered tissues through in vitro cultivation in bioreactor systems requires a thorough understanding of the complex interplay between hydrodynamic forces and biochemical cues such as serum. To this end, chondrocyte-seeded constructs were cultured under continuous fluid-induced shear forces with reduced serum content (0%-2%, v/v), which was partially or completely replaced by a potential substitute, insulin-transferrin-selenium, to minimize deleterious effects associated with the use of culture media containing high levels of serum (10%-20%). Low-serum cultures yielded constructs with similar biochemical properties to those cultivated with high-serum supplements, whereas the serum-free constructs exhibited poor cell proliferation, insufficient extracellular matrix production, and rapid degradation of and/or shear-induced damage to polyglycolic acid scaffolds. A fibrous outer capsule typically observed in hydrodynamic cultures and characterized by increased cell density and decreased (virtually none) glycosaminoglycan deposition was eliminated when serum concentration was equal to or <0.2% in the presence of hydrodynamic stimuli. Our findings suggest that serum is a requirement in insulin-transferrin-selenium-supplemented cultures in order for constructs to exhibit improved properties in response to hydrodynamic forces, and that mechanical and biochemical stimuli may synergistically modulate tissue properties and morphology through shear-responsive signals.

Industrial hygiene evaluation of thermal degradation products from PVC film in meat-wrapping operations.

PubMed

Cook, W A

1980-07-01

An industrial hygiene evaluation is presented concerning experimental data included in the preceding paper on thermal degradation products from hot-wire and "cool"-rod cutting of PVC film but, in this paper, limited to film used in meat-wrapping operations. Room air concentrations of less than 0.2 ppm HCl and less than 0.05 ppm benzene can be maintained by a number of factors, including minimal dilution ventilation. Estimates of room air concentrations of degradation products are presented using average values of amounts produced per cut. The relation of these concentrations to TLV's is given, together with methods of suggesting TLV's for substances not listed by ACGIH or OSHA. Room air concentrations for the 12 degradation products for which TLV's are assigned, based on average values per cut, were no greater than 0.3% of accepted limits. Room air concentrations of DOA are not determinable from available data but present information does not indicate that exposure to DOA causes airway hyperreactivity. The cool rod, rather than the hot wire, is recommended as good industrial hygiene practice, producing no apparent PVC degradation products, even though similar amounts of DOA are volatilized.

Enhanced photocatalytic hydrogen production from aqueous sulfide/sulfite solution by ZnO0.6S0.4 with simultaneous dye degradation under visible-light irradiation.

PubMed

Chu, Ka Him; Ye, Liqun; Wang, Wei; Wu, Dan; Chan, Donald Ka Long; Zeng, Cuiping; Yip, Ho Yin; Yu, Jimmy C; Wong, Po Keung

2017-09-01

Photocatalytic hydrogen (H 2 ) production was performed by visible-light-driven (VLD) ternary photocatalyst, zinc oxysulfide (ZnO 0.6 S 0.4 ) in the presence of sulfide/sulfite (S 2 2- /SO 3 2- ) sacrificing system, with simultaneous azo-dye Reactive Violet 5 (RV5) degradation. Enhancement in both RV5 degradation and H 2 production was achieved, with the promotion of H 2 production after decolorization of RV5. The effect of initial concentration of RV5 was found to be influential on the enhancement of H 2 during the simultaneous processes, with a maximum of 110% increase of H 2 produced. The mechanism of the simultaneous system was investigated by scavenger study and intermediate analysis, including Fourier transform-infrared (FTIR) spectroscopy and total organic carbon (TOC) analysis. It was confirmed that the partial degradation of RV5 and presence of dynamic organic intermediates contributed to the enhancement in H 2 production. The present study revealed the feasibility of developing VLD photocatalysis as a sustainable and environmentally friendly technology for concurrent organic pollutant degradation with energy generation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental toxicology of pyrolysis and combustion hazards.

PubMed Central

Cornish, H H; Hahn, K J; Barth, M L

1975-01-01

Data are presented on the acute toxicity (mortality only) of the thermal degradation products of polymers obtained by two methods of degradation. One system utilized a slowly increasing temperature (5 degrees C/min) and gradual degradation of the polymer with the rats being exposed to degradation products as they were evolved. In this system the more toxic polymers included wool, polypropylene, poly(vinyl chloride), and urethane foam. The second system utilized conditions of rapid combustion and exposure of rats to the total products of combustion for a period of 4 hr. In this system the more toxic materials included red oak, cotton, acrylonitrile-butadiene-styrene (ABS), and styrene-acrylonitrile. It is of interest to note that the natural product wool is among the least toxic under these rapid combustion conditions and among the most toxic under slow pyrolysis conditions. Other materials also vary in the comparative toxicity of their thermal degradation products, depending upon the conditions of degradation and animal exposure. The two experimental techniques presented here may well represent the two extreme conditions of rapid combustion versus slow pyrolysis. Intermediate types of fire situations might be expected to result in relative acute toxicities somewhere between these two extremes. This report deals with acute toxicity on the basis of mortality data only and does not include other parameters of toxicity such as organ weights and histopathology. PMID:1175552

Rumen modulatory effect of thyme, clove and peppermint oils in vitro using buffalo rumen liquor.

PubMed

Roy, Debashis; Tomar, S K; Kumar, Vinod

2015-02-01

The present study was conducted to examine the rumen modulatory effect of thyme, clove and peppermint oils on rumen fermentation pattern in vitro using roughage based diet. Thyme, clove and peppermint oils were tested at concentration of 0, 30, 300 and 600 mg/l (ppm) of total culture fluid using in vitro gas production technique in wheat straw based diet (concentrate: Wheat straw 50:50). Different in vitro parameters e.g., total gas production, methane production, nutrient degradability, volatile fatty acid (VFA) production and ammonia nitrogen concentration were studied using buffalo rumen liquor. Thyme oil at higher dose level (600 ppm) reduced (p<0.05) total gas production, feed degradability and ammonia nitrogen (NH3-N) concentration whereas total VFA concentration was significantly lower (p>0.05) in 300 and 600 ppm dose levels. 600 ppm dose level of clove oil reduced (p<0.05) total gas production, feed degradability, total VFA and acetate to propionate ratio. Methane production was significantly reduced (p<0.05) in 300 and 600 ppm dose levels of clove and peppermint oil. Right combination of these essential oils may prove to enhance performance of animals by reducing methane production and inhibiting protein degradation in rumen.

Degradation of fluoroquinolone antibiotics during ionizing radiation treatment and assessment of antibacterial activity, toxicity and biodegradability of the products

NASA Astrophysics Data System (ADS)

Tegze, Anna; Sági, Gyuri; Kovács, Krisztina; Homlok, Renáta; Tóth, Tünde; Mohácsi-Farkas, Csilla; Wojnárovits, László; Takács, Erzsébet

2018-06-01

This work aimed at investigating the ionizing radiation induced degradation of two fluoroquinolone antibiotics: norfloxacin and ciprofloxacin. At 0.1 mmol dm-3 concentration a low dose, 2 kGy was sufficient to degrade the initial molecules. However, despite of the high removal efficiency the degrees of both the mineralization and the oxidation were low, ∼10% and ∼25%, respectively. (The difference between the results obtained in norfloxacin and ciprofloxacin solutions was not statistically significant.) Broth microdilution tests carried out on Staphylococcus aureus evidenced removal of antibacterial activity in samples irradiated with 2 kGy. Acute toxicity determined on Vibrio fischeri bacteria showed increased toxicity at low doses indicating that the early degradation products were more toxic than the initial molecules. The results of biodegradation experiments performed in activated sludge have shown that the degradation products have become available to the metabolic processes of the microorganisms.

Degradation of phorbol esters by Pseudomonas aeruginosa PseA during solid-state fermentation of deoiled Jatropha curcas seed cake.

PubMed

Joshi, Chetna; Mathur, Priyanka; Khare, S K

2011-04-01

Large amount of seed cake is generated as by-product during biodiesel production from Jatropha seeds. Presence of toxic phorbol esters restricts its utilization as livestock feed. Safe disposal or meaningful utilization of this major by-product necessitates the degradation of these phorbol esters. The present study describes the complete degradation of phorbol esters by Pseudomonas aeruginosa PseA strain during solid state fermentation (SSF) of deoiled Jatropha curcas seed cake. Phorbol esters were completely degraded in nine days under the optimized SSF conditions viz. deoiled cake 5.0 g; moistened with 5.0 ml distilled water; inoculum 1.5 ml of overnight grown P. aeruginosa; incubation at temperature 30 °C, pH 7.0 and RH 65%. SSF of deoiled cake seems a potentially viable approach towards the complete degradation of the toxic phorbol esters. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of Fe(III) on 1,1,2,2-Tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the Aberdeen Proving Ground

USGS Publications Warehouse

Jones, Elizabeth; Voytek, Mary; Lorah, Michelle

2004-01-01

1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek (MD), where dechlorination occurs. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways lead to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The goal of this investigation was to determine whether microbially-available Fe(III) in the wetland surface sediment influenced the fate of TeCA and its daughter products. Differences were identified in the TeCA degradation pathway between microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated microcosms than untreated microcosms. The microcosm incubations and subsequent experiments with the microcosm materials showed that AFO treatment resulted in lower production of VC by (1) shifting TeCA degradation from dichloroelimination pathways to production of a greater proportion of chlorinated ethane products, and (2) decreasing the microbial capability to produce VC from 1,2-dichloroethene (DCE). VC degradation was not stimulated in the presence of Fe(III). Rather, VC degradation occurred readily under methanogenic conditions and was inhibited under Fe(III)-reducing conditions.

Degradation of α-Naphthol by Plasma in Aqueous Solution

NASA Astrophysics Data System (ADS)

Gao, Jin-zhang; Hu, Zhong-ai; Wang, Xiao-yan; Hou, Jing-guo; Lu, Xiao-quan; Kang, Jing-wan

2001-02-01

Degradation of α-naphthol induced by plasma in aqueous solution was investigated in different initial concentration with contact glow discharge electrolysis (CGDE). The results showed that the degradation of α-naphthol obeyed the first-rate law. Some of predominant products were analyzed by a high performance liquid chromatography (HPLC). A path of α-naphthol disappearance caused by plasma was proposed according to the detected intermediate products.

Interaction of an anticancer peptide fragment of azurin with p53 and its isolated domains studied by atomic force spectroscopy.

PubMed

Bizzarri, Anna Rita; Santini, Simona; Coppari, Emilia; Bucciantini, Monica; Di Agostino, Silvia; Yamada, Tohru; Beattie, Craig W; Cannistraro, Salvatore

2011-01-01

p28 is a 28-amino acid peptide fragment of the cupredoxin azurin derived from Pseudomonas aeruginosa that preferentially penetrates cancerous cells and arrests their proliferation in vitro and in vivo. Its antitumor activity reportedly arises from post-translational stabilization of the tumor suppressor p53 normally downregulated by the binding of several ubiquitin ligases. This would require p28 to specifically bind to p53 to inhibit specific ligases from initiating proteosome-mediated degradation. In this study, atomic force spectroscopy, a nanotechnological approach, was used to investigate the interaction of p28 with full-length p53 and its isolated domains at the single molecule level. Analysis of the unbinding forces and the dissociation rate constant suggest that p28 forms a stable complex with the DNA-binding domain of p53, inhibiting the binding of ubiquitin ligases other than Mdm2 to reduce proteasomal degradation of p53.

Interaction of an anticancer peptide fragment of azurin with p53 and its isolated domains studied by atomic force spectroscopy

PubMed Central

Bizzarri, Anna Rita; Santini, Simona; Coppari, Emilia; Bucciantini, Monica; Di Agostino, Silvia; Yamada, Tohru; Beattie, Craig W; Cannistraro, Salvatore

2011-01-01

p28 is a 28-amino acid peptide fragment of the cupredoxin azurin derived from Pseudomonas aeruginosa that preferentially penetrates cancerous cells and arrests their proliferation in vitro and in vivo. Its antitumor activity reportedly arises from post-translational stabilization of the tumor suppressor p53 normally downregulated by the binding of several ubiquitin ligases. This would require p28 to specifically bind to p53 to inhibit specific ligases from initiating proteosome-mediated degradation. In this study, atomic force spectroscopy, a nanotechnological approach, was used to investigate the interaction of p28 with full-length p53 and its isolated domains at the single molecule level. Analysis of the unbinding forces and the dissociation rate constant suggest that p28 forms a stable complex with the DNA-binding domain of p53, inhibiting the binding of ubiquitin ligases other than Mdm2 to reduce proteasomal degradation of p53. PMID:22162658

Current challenges in distinguishing climatic and anthropogenic contributions to alpine grassland variation on the Tibetan Plateau.

PubMed

Li, Lanhui; Zhang, Yili; Liu, Linshan; Wu, Jianshuang; Li, Shicheng; Zhang, Haiyan; Zhang, Binghua; Ding, Mingjun; Wang, Zhaofeng; Paudel, Basanta

2018-06-01

Quantifying the impact of climate change and human activities on grassland dynamics is an essential step for developing sustainable grassland ecosystem management strategies. However, the direction and magnitude of climate change and human activities in driving alpine grassland dynamic over the Tibetan Plateau remain under debates. Here, we systematically reviewed the relevant studies on the methods, main conclusions, and causes for the inconsistency in distinguishing the respective contribution of climatic and anthropogenic forces to alpine grassland dynamic. Both manipulative experiments and traditional statistical analysis show that climate warming increase biomass in alpine meadows and decrease in alpine steppes, while both alpine steppes and meadows benefit from an increase in precipitation or soil moisture. Overgrazing is a major factor for the degradation of alpine grassland in local areas with high level of human activity intensity. However, across the entire Tibetan Plateau and its subregions, four views characterize the remaining controversies: alpine grassland changes are primarily due to (1) climatic force, (2) nonclimatic force, (3) combination of anthropogenic and climatic force, or (4) alternation of anthropogenic and climatic force. Furthermore, these views also show spatial inconsistencies. Differences on the source and quality of remote sensing products, the structure and parameter of models, and overlooking the spatiotemporal heterogeneity of human activity intensity contribute to current disagreements. In this review, we highlight the necessity for taking the spatiotemporal heterogeneity of human activity intensity into account in the models of attribution assessment, and the importance for accurate validation of climatic and anthropogenic contribution to alpine grassland variation at multiple scales for future studies.

Photocatalytic mineralization and degradation kinetics of sulphamethoxazole and reactive red 194 over silver-zirconium co-doped titanium dioxide: Reaction mechanisms and phytotoxicity assessment.

PubMed

Naraginti, Saraschandra; Li, Yi; Puma, Gianluca Li

2018-09-15

The photodegradation and phytotoxicity of the pharmaceutical antibiotic, sulphamethoxazole (SMX) and the azo-dye reactive-red-194 (RR194) under visible-light irradiation of TiO 2 nanoparticles modified by silver and zirconium was investigated. The results indicated that sulphamethoxazole and its toxic degradation by product, 3-amino-5-methylisoxazole and RR-194 could be degraded efficiently by the co-doped Zr/Ag-TiO 2 catalyst. PL studies and ROS generation results suggested that the effective charge separation was carried out while irradiation of the modified TiO 2 nanoparticles. Phytotoxicity tests demonstrated lower percentage of germination in P. vulgaris (40%), V. radiata (30%) and P. lunatus (30%) of the seeds treated with 50 ppm of SMX, compared to the seeds treated with the degradation products (100%). The results with 50 ppm of RR-194 also showed lower percentage of germination in P. vulgaris (40%), V. radiata (50%) and P. lunatus (30%) compared to the degradation products (100%). Furthermore, significant increase in root and shoot development was observed in the seeds treated with the degraded products when compared with SMX and RR-194. Overall, this study contributes to further understanding the photodegradation mechanisms, degradation products and environmental fate of SMX and RR-194 in water which helps in the evaluation and mitigation of the environmental risk of SMX and RR-194 for water reuse and crop irrigation. Crown Copyright © 2018. Published by Elsevier Inc. All rights reserved.

Thermal Degradation Studies of Polyurethane/POSS Nanohybrid Elastomers

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

Lewicki, J P; Pielichowski, K; TremblotDeLaCroix, P

2010-03-05

Reported here is the synthesis of a series of Polyurethane/POSS nanohybrid elastomers, the characterization of their thermal stability and degradation behavior at elevated temperatures using a combination of Thermal Gravimetric Analysis (TGA) and Thermal Volatilization Analysis (TVA). A series of PU elastomers systems have been formulated incorporating varying levels of 1,2-propanediol-heptaisobutyl-POSS (PHIPOSS) as a chain extender unit, replacing butane diol. The bulk thermal stability of the nanohybrid systems has been characterized using TGA. Results indicate that covalent incorporation of POSS into the PU elastomer network increase the non-oxidative thermal stability of the systems. TVA analysis of the thermal degradation ofmore » the POSS/PU hybrid elastomers have demonstrated that the hybrid systems are indeed more thermally stable when compared to the unmodified PU matrix; evolving significantly reduced levels of volatile degradation products and exhibiting a {approx}30 C increase in onset degradation temperature. Furthermore, characterization of the distribution of degradation products from both unmodified and hybrid systems indicate that the inclusion of POSS in the PU network is directly influencing the degradation pathways of both the soft and hard block components of the elastomers: The POSS/PU hybrid systems show reduced levels of CO, CO2, water and increased levels of THF as products of thermal degradation.« less

Quantifying South East Asia's forest degradation using latest generation optical and radar satellite remote sensing

NASA Astrophysics Data System (ADS)

Broich, M.; Tulbure, M. G.; Wijaya, A.; Weisse, M.; Stolle, F.

2017-12-01

Deforestation and forest degradation form the 2nd largest source of anthropogenic CO2 emissions. While deforestation is being globally mapped with satellite image time series, degradation remains insufficiently quantified. Previous studies quantified degradation for small scale, local sites. A method suitable for accurate mapping across large areas has not yet been developed due to the variability of the low magnitude and short-lived degradation signal and the absence of data with suitable resolution properties. Here we use a combination of newly available streams of free optical and radar image time series acquired by NASA and ESA, and HPC-based data science algorithms to innovatively quantify degradation consistently across Southeast Asia (SEA). We used Sentinel1 c-band radar data and NASA's new Harmonized Landsat8 (L8) Sentinel2 (S2) product (HLS) for cloud free optical images. Our results show that dense time series of cloud penetrating Sentinel 1 c-band radar can provide degradation alarm flags, while the HLS product of cloud-free optical images can unambiguously confirm degradation alarms. The detectability of degradation differed across SEA. In the seasonal forest of continental SEA the reliability of our radar-based alarm flags increased as the variability in landscape moisture decreases in the dry season. We reliably confirmed alarms with optical image time series during the late dry season, where degradation in open canopy forests becomes detectable once the undergrowth vegetation has died down. Conversely, in insular SEA landscape moisture is low, the radar time series generated degradation alarms flags with moderate to high reliability throughout the year, further confirmed with the HLS product. Based on the HLS product we can now confirm degradation within < 6 months on average as opposed to 1 year when using either L8 or S2 alone. In contrast to continental SEA, across insular SEA our degradation maps are not suitable to provide annual maps of total degradation area, but can pinpoint degradation areas on a rolling basin throughout the year. In both continental SEA and insular SEA there the combination of optical and radar time series provides better results than either one on its own. Our results provide significant information with application for carbon trading policy and land management.

Impact of CO2-solvent separators on the degradation of benzyl-2,3-dihydroxypiperidine-1-carboxylate during preparative supercritical fluid chromatographic (SFC) purification.

PubMed

Asokan, Kathiravan; Naidu, Harshavardhan; Madam, Ratalababu; Shaikh, Khaja Mohiuddin; Reddy, Manjunath; Kumar, Hemantha; Shirude, Pravin S; Rajendran, Muruganantham; Sarabu, Ramakanth; Wu, Dauh-Rurng; Bajpai, Lakshmikant; Zhang, Yingru

2017-12-29

During a preparative separation of the cis enantiomeric pair of benzyl-2,3-dihydroxypiperidine-1-carboxylate using supercritical-fluid chromatography (SFC) with methanol modifier, significant degradation of the products in the collected fractions was observed when a Waters SFC-350 ® (Milford, MA, USA) was used, but same was not observed when a Waters SFC-80q ® (Milford, MA, USA) was used. Through a systematic investigation, we discovered that the compound degraded over time under an acidic condition created by the formation of methyl carbonic acid from methanol and CO 2. The extent of the product degradation was dependent on the time and the concentration of CO 2 remained in the product fraction, which was governed by the efficiency of CO 2 -methanol separation during the fraction collection. Hence, we demonstrated that the different designs of CO 2 -solvent separator (high pressurized cyclone in Waters SFC-350 ® and low-pressurized vortexing separator in Waters SFC-80q ®® ) had a significant impact on the degradation of an acid-sensitive compound. The acidity caused by CO 2 in methanol was supported by diminished degradation after a nitrogen purging or after neutralizing the collected fractions with a base. Three different solutions to overcome the degradation problem of the acid sensitive compounds using SFC-350 ® with the high pressurized separator were investigated and demonstrated. The degraded products were isolated as four enantiomers and their relative stereochemistry were established based on 2D NMR data along with the plausible mechanism of degradation. Copyright © 2017 Elsevier B.V. All rights reserved.

Biofilm lifestyle enhances diesel bioremediation and biosurfactant production in the Antarctic polyhydroxyalkanoate producer Pseudomonas extremaustralis.

PubMed

Tribelli, Paula M; Di Martino, Carla; López, Nancy I; Raiger Iustman, Laura J

2012-09-01

Diesel is a widely distributed pollutant. Bioremediation of this kind of compounds requires the use of microorganisms able to survive and adapt to contaminated environments. Pseudomonas extremaustralis is an Antarctic bacterium with a remarkable survival capability associated to polyhydroxyalkanoates (PHAs) production. This strain was used to investigate the effect of cell growth conditions--in biofilm versus shaken flask cultures--as well as the inocula characteristics associated with PHAs accumulation, on diesel degradation. Biofilms showed increased cell growth, biosurfactant production and diesel degradation compared with that obtained in shaken flask cultures. PHA accumulation decreased biofilm cell attachment and enhanced biosurfactant production. Degradation of long-chain and branched alkanes was observed in biofilms, while in shaken flasks only medium-chain length alkanes were degraded. This work shows that the PHA accumulating bacterium P. extremaustralis can be a good candidate to be used as hydrocarbon bioremediation agent, especially in extreme environments.

Detection of cephradine through the electrochemical study of the degradation product of cephradine

NASA Astrophysics Data System (ADS)

Jiang, Qingfeng; Ying, Yibin; Wang, Jianping; Ye, Zunzhong; Li, Yanbin

2005-11-01

The degradation product of cephradine(CEP), a broad spectrum antibiotic, with NaOH was studied in solution by Cyclic Voltammetry and Differential Pulse Voltammetry at a three electrode system (Gold working electrode, Hg/HgCl reference electrode and Platinum counter electrode). Our experiment was based on that the R-SH in degradation product could cause a deoxidization peak at gold working electrode. The response was optimized with respect to accumulation time, ionic strength, drug concentration, reproducibility and other variables. We found that the degradation product of CEP in Na2HPO4-NaH2PO4 buffer could cause a sensitive deoxidization peak at -0.68V. A linear dependence of peak currents on the concentration was observed in the range of 10-7 - 10-6 mol/L, with a detection limit of 0.5*10-7mol/L. This method can achieve satisfactory results in the application of detecting human-made CEP.

NMR Studies on the Aqueous Phase Photochemical Degradation of TNT

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

Thorn, Kevin A.; Cox, Larry G.

2008-04-06

Aqueous phase photochemical degradation of 2,4,6-trinitrotoluene (TNT) is an important pathway in several environments, including washout lagoon soils, impact craters from partially detonated munitions that fill with rain or groundwater, and shallow marine environments containing unexploded munitions that have corroded. Knowledge of the degradation products is necessary for compliance issues on military firing ranges and formerly used defense sites. Previous laboratory studies have indicated that UV irradiation of aqueous TNT solutions results in a multicomponent product mixture, including polymerization compounds, that has been only partially resolved by mass spectrometric analyses. This study illustrates how a combination of solid and liquidmore » state 1H, 13C, and 15N NMR spectroscopy, including two dimensional analyses, provides complementary information on the total product mixture from aqueous photolysis of TNT, and the effect of reaction conditions. Among the degradation products detected were amine, amide, azoxy, azo, and carboxylic acid compounds.« less

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

PubMed

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%.

A remote sensing protocol for identifying rangelands with degraded productive capacity

Treesearch

Matthew C. Reeves; L. Scott Bagget

2014-01-01

Rangeland degradation is a growing problem throughout the world. An assessment process for com-paring the trend and state of vegetation productivity to objectively derived reference conditions wasdeveloped. Vegetation productivity was estimated from 2000 to 2012 using annual maximum Normalized Difference Vegetation Index (NDVI) from the MODIS satellite platform. Each...

The Author’s Guide To Writing 412th Test Wing Technical Reports

DTIC Science & Technology

2014-12-01

control CAD computer aided design cc cubic centimeters C.O. carry-over c/o checkout USAF United States Air Force C1 rolling moment coefficient...cooling air. Mission Impact: Results in maintenance inability to reliably duplicate and isolate valid aircraft failures, and degrades reliability...air. Mission Impact: Results in maintenance inability to reliably duplicate and isolate valid aircraft failures, and degrades reliability of system

Stressed Stability Techniques for Adjuvant Formulations.

PubMed

Hasija, Manvi; Sheung, Anthony; Rahman, Nausheen; Ausar, Salvador F

2017-01-01

Stressed stability testing is crucial to the understanding of mechanisms of degradation and the effects of external stress factors on adjuvant stability. These studies vastly help the development of stability indicating tests and the selection of stabilizing conditions for long term storage. In this chapter, we provide detailed protocols for the execution of forced degradation experiments that evaluate the robustness of adjuvant formulations against thermal, mechanical, freeze-thawing, and photo stresses.

Production and degradation of polyhydroxyalkanoates in waste environment

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

Lee, S.Y.; Choi, J.

1999-06-01

Polyhydroxyalkanoates (PHAs) are energy/carbon storage materials accumulated under unfavorable growth condition in the presence of excess carbon source. PHAs are attracting much attention as substitute for non-degradable petrochemically derived plastics because of their similar material properties to conventional plastics and complete biodegradability under natural environment upon disposal. In this paper, PHA production and degradation in waste environment as well as its role in biological phosphorus removal are reviewed. In biological phosphorus removal process, bacteria accumulating polyphosphate (poly P) uptake carbon substrates and accumulate these as PHA by utilizing energy from breaking down poly P under anaerobic conditions. In the followingmore » aerobic condition, accumulated PHA is utilized for energy generation and for the regeneration of poly P. PHA production from waste has been investigated in order to utilize abundant organic compounds in waste water. Since PHA content and PHA productivity that can be obtained are rather low, PHA production from waste product should be considered as a coupled process for reducing the amount of organic waste. PHAs can be rapidly degraded to completion in municipal anaerobic sludge by various microorganisms.« less

Proteinases secreted by Fasciola hepatica degrade extracellular matrix and basement membrane components.

PubMed

Berasaín, P; Goñi, F; McGonigle, S; Dowd, A; Dalton, J P; Frangione, B; Carmona, C

1997-02-01

The invasive stages of the parasitic trematode Fasciola hepatica release proteinases into the medium in which they are maintained. In this study, we investigated the interaction of F. hepatica excretory/secretory (E/S) products and 2 cysteine proteinases (CL1 and CL2) purified from these products with extracellular matrix and basement membrane macromolecules. Fasciola hepatica E/S products contained collagenolytic activity on fibrillar types I and III collagen as well as basement membrane type IV collagen. CL1 and CL2 were capable of degrading acid-soluble type III and type IV collagen but not insoluble type I collagen. In contrast, neither the E/S products nor the purified CL1 and CL2 showed elastinolytic activity. Fibronectin and laminin were degraded by E/S products and by CL1 and CL2. Sequence analysis of fibronectin degradation products showed that the fragments obtained corresponded to complete biologically active domains. These results indicate that the cysteine proteinases secreted by F. hepatica may be involved in the process of tissue invasion by the parasite.

Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment.

PubMed

Avonto, Cristina; Wang, Mei; Chittiboyina, Amar G; Vukmanovic, Stanislav; Khan, Ikhlas A

2018-02-01

Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of trimethoprim by gamma irradiation in the presence of persulfate

NASA Astrophysics Data System (ADS)

Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

2016-10-01

The degradation and mineralization of trimethoprim (TMP) by gamma irradiation was investigated in the presence of persulfate (PS). The TMP was degraded at initial concentration of 20 mg/L in aqueous solution with addition of 0, 0.5, 1, 1.5, 2 mM persulfate respectively. The effect of pH values (6.5, 7.5 and 8.5) on TMP degradation was also determined. The experimental results showed that the degradation and mineralization of TMP could be significantly enhanced by persulfate at acidic condition (pH=6.5). Several intermediate products generated during gamma irradiation process through hydroxylation, demethylation and cleavage were identified using liquid chromatography with tandem mass spectrometry (HPLC-MS). The degradation pathway of TMP was tentatively proposed based on the identification of intermediate products.

Investigating the chlorination of acidic pharmaceuticals and by-product formation aided by an experimental design methodology.

PubMed

Quintana, José Benito; Rodil, Rosario; López-Mahía, Purificación; Muniategui-Lorenzo, Soledad; Prada-Rodríguez, Darío

2010-01-01

The degradation of seven acidic drugs and two metabolites during chlorination was investigated by liquid chromatography-mass spectrometry (LC-MS). A triple-quadrupole (QqQ) system was used to follow the time course of the pharmaceuticals and by-products, while a quadrupole time-of-flight (Q-TOF) system was also used for the identification of the by-products. Under strong chlorination conditions (10mg/L Cl(2), 24h), only four of the target compounds were significantly degraded: salicylic acid, naproxen, diclofenac and indomethacine. The degradation kinetics of these four compounds were investigated at different concentrations of chlorine, bromide and pH by means of a Box-Behnken experimental design. Depending on these factors, measured pseudo-first order half-lives were in the ranges: 23-573h for salicylic acid, 13-446min for naproxen, 5-328min for diclofenac and 0.4-13.4min for indomethacine. Also, it was observed that chlorine concentration was the overall most significant factor, followed by the bromide concentration (except for indomethacine), resulting in increased degradation kinetics as they are increased. The degradation path of salicylic acid, naproxen and diclofenac consisted of aromatic substitution of one or two hydrogens by chlorine and/or bromide. Moreover, for diclofenac, two other by-products corresponding to a decarboxylation/hydroxylation pathway from the monohalogenated products were also identified. On the other hand, indomethacine degradation did not lead to halogenation products but to oxidation ones. The investigation of these by-products in real samples by LC-MS/MS (QqQ) showed that the halogenated derivates of salicylic acid occurred in all the drinking water and wastewater samples analysed.

Identification of degradation products in loxoprofen sodium adhesive tapes by liquid chromatography-mass spectrometry and dynamic pressurized liquid extraction-solid-phase extraction coupled to liquid chromatography-nuclear magnetic resonance spectroscopy.

PubMed

Murakami, Tomonori; Kawasaki, Takao; Takemura, Akira; Fukutsu, Naoto; Kishi, Naoyuki; Kusu, Fumiyo

2008-10-24

Rapid and unambiguous identification of three degradation products (DP-1, DP-2 and DP-3) found in heat-stressed loxoprofen sodium adhesive tapes (Loxonin tapes) was achieved by LC-MS and dynamic pressurized liquid extraction (PLE)-solid-phase extraction (SPE) coupled to LC-NMR without complicated isolation or purification processes. The molecular formulae of the degradation products were determined by accurate mass measurements and product ion analyses and on-line hydrogen/deuterium (H/D) exchange experiments provided information about changes in the degradation of loxoprofen. To compensate for the low sensitivity of NMR, on-line dynamic PLE-SPE was employed and higher concentrations of degradation products trapped on the SPE column were afforded in a shorter time than they would be in such time-consuming sample preparations as pre-concentration after extraction. The loop-storage procedure was used in the LC-NMR analysis to allow the acquisition of the (1)H spectra of the three degradation products in one chromatographic run without affecting the peak separation and to avoid the carry-over of previously eluted DP-1 of high concentration by washing the NMR detection cell prior to the measurement of the DP-2 spectrum. Based on the resulting (1)H NMR spectra in combination with the MS results, DP-1 was successfully identified as an oxidation product having an oxodicarboxylic acid structure formed by the cleavage of the cyclopentanone ring of loxoprofen, DP-2 as a cyclopentanone ring-hydroxylated loxoprofen and DP-3 as a loxoprofen l-menthol ester.

[Advances in plant ecophysiological studies on re-vegetation of degraded ecosystem].

PubMed

Zhao, Ping

2003-11-01

Natural force and human intervention lead to many local, regional, and sometimes global changes in plant community patterns. Regardless of the cause and intensity of these changes, ecosystem can recover most of their attributes through natural succession, or can be repaired by human assistance. The essentiality of restoration of degraded ecosystem is community succession, a process during which an ecosystem evolves from primary stage to advanced stage, and its structure and function change from simple to complex plant. Ecophysiological study could explain some macroscopical phenomena of the ecology of re-vegetation of degraded ecosystem, and provide a scientific base for assembling pioneering plant community. The advances in plant ecophysiological study on re-vegetation of degraded ecosystems were reviewed in this paper.

Degradation of 4-Chlorophenol Under Sunlight Using ZnO Nanoparticles as Catalysts

NASA Astrophysics Data System (ADS)

Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Sherazi, Tufail H.; Kumar, Raj

2018-03-01

Herein we demonstrate a simplistic microwave assisted chemical precipitation approach regarding the synthesis of zinc oxide nanoparticles. As-prepared ZnO nanoparticles (NPs) were characterized by UV-visible spectroscopy, Fourier transform infra-red spectroscopy, atomic force microscopy and x-ray diffractometry and scrutinized as photo-catalysts for degradation of 4-chlorophenol (4-CP) under sunlight. The study substantiated that 98.5% of 4-CP was degraded within 20 min in the absence of initiator like H2O2 which reflects an outstanding prospective use for ZnO NPs as photo-catalysts. The nanocatalysts were recycled four times and still showed catalytic efficiency up to 95.5% for degradation of 4-CP in the specified 20 min.

Pathways for degradation of plastic polymers floating in the marine environment.

PubMed

Gewert, Berit; Plassmann, Merle M; MacLeod, Matthew

2015-09-01

Each year vast amounts of plastic are produced worldwide. When released to the environment, plastics accumulate, and plastic debris in the world's oceans is of particular environmental concern. More than 60% of all floating debris in the oceans is plastic and amounts are increasing each year. Plastic polymers in the marine environment are exposed to sunlight, oxidants and physical stress, and over time they weather and degrade. The degradation processes and products must be understood to detect and evaluate potential environmental hazards. Some attention has been drawn to additives and persistent organic pollutants that sorb to the plastic surface, but so far the chemicals generated by degradation of the plastic polymers themselves have not been well studied from an environmental perspective. In this paper we review available information about the degradation pathways and chemicals that are formed by degradation of the six plastic types that are most widely used in Europe. We extrapolate that information to likely pathways and possible degradation products under environmental conditions found on the oceans' surface. The potential degradation pathways and products depend on the polymer type. UV-radiation and oxygen are the most important factors that initiate degradation of polymers with a carbon-carbon backbone, leading to chain scission. Smaller polymer fragments formed by chain scission are more susceptible to biodegradation and therefore abiotic degradation is expected to precede biodegradation. When heteroatoms are present in the main chain of a polymer, degradation proceeds by photo-oxidation, hydrolysis, and biodegradation. Degradation of plastic polymers can lead to low molecular weight polymer fragments, like monomers and oligomers, and formation of new end groups, especially carboxylic acids.

Characterization and Degradation of Pectic Polysaccharides in Cocoa Pulp.

PubMed

Meersman, Esther; Struyf, Nore; Kyomugasho, Clare; Jamsazzadeh Kermani, Zahra; Santiago, Jihan Santanina; Baert, Eline; Hemdane, Sami; Vrancken, Gino; Verstrepen, Kevin J; Courtin, Christophe M; Hendrickx, Marc; Steensels, Jan

2017-11-08

Microbial fermentation of the viscous pulp surrounding cocoa beans is a crucial step in chocolate production. During this process, the pulp is degraded, after which the beans are dried and shipped to factories for further processing. Despite its central role in chocolate production, pulp degradation, which is assumed to be a result of pectin breakdown, has not been thoroughly investigated. Therefore, this study provides a comprehensive physicochemical analysis of cocoa pulp, focusing on pectic polysaccharides, and the factors influencing its degradation. Detailed analysis reveals that pectin in cocoa pulp largely consists of weakly bound substances, and that both temperature and enzyme activity play a role in its degradation. Furthermore, this study shows that pulp degradation by an indigenous yeast fully relies on the presence of a single gene (PGU1), encoding for an endopolygalacturonase. Apart from their basic scientific value, these new insights could propel the selection of microbial starter cultures for more efficient pulp degradation.

Nanoparticles from Degradation of Biodegradable Plastic Mulch

NASA Astrophysics Data System (ADS)

Flury, Markus; Sintim, Henry; Bary, Andy; English, Marie; Schaefer, Sean

2017-04-01

Plastic mulch films are commonly used in crop production. They provide multiple benefits, including control of weeds and insects, increase of soil and air temperature, reduction of evaporation, and prevention of soil erosion. The use of plastic mulch film in agriculture has great potential to increase food production and security. Plastic mulch films must be retrieved and disposed after usage. Biodegradable plastic mulch films, who can be tilled into the soil after usage offer great benefits as alternative to conventional polyethylene plastic. However, it has to be shown that the degradation of these mulches is complete and no micro- and nanoparticles are released during degradation. We conducted a field experiment with biodegradable mulches and tested mulch degradation. Mulch was removed from the field after the growing season and composted to facilitate degradation. We found that micro- and nanoparticles were released during degradation of the mulch films in compost. This raises concerns about degradation in soils as well.

Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

PubMed

Zhang, Jie; Yin, Binjie; Xie, Yuhuai; Li, Jing; Yang, Zaibin; Zhang, Guiguo

2015-01-01

Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2) involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM) and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a), potentially degradable (b) and the degradation rate constant (c) of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP) yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value) of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn-rye exhibited a greater forage production potential, and could be applied as forage supply source for ruminants. The improved effective degradability of harvest mixture material could be attributed to greater degradable components involving the rapidly degradable fractions (a), potentially degradable (b) fractions, and degradable rate constant (c), than that of corn and rye hay.

Mechanisms Underpinning Degradation of Protective Oxides and Thermal Barrier Coatings in High Hydrogen Content (HHC) - Fueled Turbines

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

Mumm, Daniel

2013-08-31

The overarching goal of this research program has been to evaluate the potential impacts of coal-derived syngas and high-hydrogen content fuels on the degradation of turbine hot-section components through attack of protective oxides and thermal barrier coatings. The primary focus of this research program has been to explore mechanisms underpinning the observed degradation processes, and connections to the combustion environments and characteristic non-combustible constituents. Based on the mechanistic understanding of how these emerging fuel streams affect materials degradation, the ultimate goal of the program is to advance the goals of the Advanced Turbine Program by developing materials design protocols leadingmore » to turbine hot-section components with improved resistance to service lifetime degradation under advanced fuels exposures. This research program has been focused on studying how: (1) differing combustion environments – relative to traditional natural gas fired systems – affect both the growth rate of thermally grown oxide (TGO) layers and the stability of these oxides and of protective thermal barrier coatings (TBCs); and (2) how low levels of fuel impurities and characteristic non-combustibles interact with surface oxides, for instance through the development of molten deposits that lead to hot corrosion of protective TBC coatings. The overall program has been comprised of six inter-related themes, each comprising a research thrust over the program period, including: (i) evaluating the role of syngas and high hydrogen content (HHC) combustion environments in modifying component surface temperatures, heat transfer to the TBC coatings, and thermal gradients within these coatings; (ii) understanding the instability of TBC coatings in the syngas and high hydrogen environment with regards to decomposition, phase changes and sintering; (iii) characterizing ash deposition, molten phase development and infiltration, and associated corrosive/thermo-chemical attack mechanisms; (iv) developing a mechanics-based analysis of the driving forces for crack growth and delamination, based on molten phase infiltration, misfit upon cooling, and loss of compliance; (v) understanding changes in TGO growth mechanisms associated with these emerging combustion product streams; and (vi) identifying degradation resistant alternative materials (including new compositions or bi-layer concepts) for use in mitigating the observed degradation modes. To address the materials stability concerns, this program integrated research thrusts aimed at: (1) Conducting tests in simulated syngas and HHC environments to evaluate materials evolution and degradation mechanisms; assessing thermally grown oxide development unique to HHC environmental exposures; carrying out high-resolution imaging and microanalysis to elucidate the evolution of surface deposits (molten phase formation and infiltration); exploring thermo-chemical instabilities; assessing thermo-mechanical drivers and thermal gradient effects on degradation; and quantitatively measuring stress evolution due to enhanced sintering and thermo-chemical instabilities induced in the coating. (2) Executing experiments to study the melting and infiltration of simulated ash deposits, and identifying reaction products and evolving phases associated with molten phase corrosion mechanisms; utilizing thermal spray techniques to fabricate test coupons with controlled microstructures to study mechanisms of instability and degradation; facilitating thermal gradient testing; and developing new materials systems for laboratory testing; (3) Correlating information on the resulting combustion environments to properly assess materials exposure conditions and guide the development of lab-scale simulations of material exposures; specification of representative syngas and high-hydrogen fuels with realistic levels of impurities and contaminants, to explore differences in heat transfer, surface degradation, and deposit formation; and facilitating combustion rig testing of materials test coupons.« less

Stability-indicating UPLC method for determination of Valsartan and their degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms.

PubMed

Krishnaiah, Ch; Reddy, A Raghupathi; Kumar, Ramesh; Mukkanti, K

2010-11-02

A simple, precise, accurate stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the quantitative determination of purity of Valsartan drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. The method was developed using Waters Aquity BEH C18 (100 mm x 2.1 mm, 1.7 microm) column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 225 nm, the run time was within 9.5 min, which Valsartan and its seven impurities were well separated. Valsartan was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Valsartan was found to degrade significantly in acid and oxidative stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per international conference on harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of Valsartan in pharmaceutical dosage forms.

Role of biphasic calcium phosphate ceramic-mediated secretion of signaling molecules by macrophages in migration and osteoblastic differentiation of MSCs.

PubMed

Wang, Jing; Liu, Dan; Guo, Bo; Yang, Xiao; Chen, Xuening; Zhu, Xiangdong; Fan, Yujiang; Zhang, Xingdong

2017-03-15

The inflammatory reaction initiates fracture healing and could play a role in the osteoinductive effect of calcium phosphate (CaP) ceramics, which has been widely confirmed; however, the underlying mechanism has not been fully elucidated. In this study, various signaling molecules from macrophages under the stimulation of osteoinductive biphasic calcium phosphate (BCP) ceramic and its degradation products were examined and evaluated for their influence on the migration and osteoblastic differentiation of mesenchymal stem cells (MSCs). The results of cellular experiments confirmed that the gene expression of most inflammatory factors (IL-1, IL-6 and MCP-1) and growth factors (VEGF, PDGF and EGF) by macrophages were up-regulated to varying degrees by BCP ceramic and its degradation products. Cell migration tests demonstrated that the conditioned media (CMs), which contained abundant signaling molecules secreted by macrophages cultured on BCP ceramic and its degradation products, promoted the migration of MSCs. qRT-PCR analysis indicated that CMs promoted the gene expression of osteogenic markers (ALP, COL-I, OSX, BSP and OPN) in MSCs. ALP activity and mineralization staining further confirmed that CMs promoted the osteoblastic differentiation of MSCs. The present study confirmed the correlation between the inflammatory reaction and osteoinductive capacity of BCP ceramic. The ceramic itself and its degradation products can induce macrophages to express and secrete various signaling molecules, which then recruit and promote the MSCs to differentiate into osteoblasts. Compared with BCP conditioned media, degradation particles played a more substantial role in this process. Thus, inflammation initiated by BCP ceramic and its degradation products could be necessary for osteoinduction by the ceramic. It is known that the inflammatory reaction initiates fracture healing. The aim of this study was to examine whether osteoinductive BCP ceramics could cause macrophages to change their secretion patterns and whether the secreted cytokines could affect migration and osteoblastic differentiation of MSCs. Moreover, the duration of inflammation could be influenced by the local ionic environment and the degradation products of the implant. Our experimental results revealed the correlation between the inflammatory reaction and osteoinductive capacity of BCP ceramic. The ceramic itself and its degradation products can induce macrophages to express and secrete various signaling molecules, which then recruit and promote the MSCs to differentiate into osteoblasts. Compared with ionic microenvironment, degradation particles played a more substantial role in this process. Therefore, the appropriate inflammation initiated by BCP ceramic and its degradation products could be essential for osteoinduction by the ceramic. We believe that the present study improves the understanding of the effect of biomaterial-mediated inflammation on MSC migration and differentiation and established a preliminary correlation between the immune system and osteoinduction by biomaterials. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Chemical stability of astaxanthin integrated into a food matrix: Effects of food processing and methods for preservation.

PubMed

Martínez-Delgado, Alejandra Anahí; Khandual, Sanghamitra; Villanueva-Rodríguez, Socorro Josefina

2017-06-15

Astaxanthin is a carotenoid pigment found in numerous organisms ranging from bacteria to algae, yeasts, plants, crustaceans and fish such as salmon. Technological importance of this pigment emerged from various studies demonstrating that it is a powerful antioxidant, even with higher activity than alpha-tocopherol and other carotenoids. It has been included in various pharmaceutical products because of several beneficial properties. By its nature, astaxanthin is susceptible to degradation and can undergo chemical changes during food processing. Therefore, different studies have focused on improving the stability of the carotenoid under conditions such as high temperatures, pressures and mechanical force, among others. In this review, common processes involved in food processing and their effect on the stability of astaxanthin, integrated into a food matrix are discussed. Moreover, preservation techniques such as microencapsulation, inclusion in emulsions, suspensions, liposomes, etc., that are being employed to maintain stability of the product are also reviewed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental investigation of a throttlable 15 cm hollow cathode ion thruster

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1972-01-01

The use of dished high perveance grids on a 15 cm modified SERT 2 thruster is shown to facilitate throttled operation over a beam current range from 60 to 600 mA. Effects of increasing the radial component of the magnetic field in the main discharge chamber and decreasing the dimensions of the cathode discharge region are examined and found to degrade performance to the extent that primary electrons are forced in toward the center-line of the thruster. Studies of the baffle aperture region of two thrusters indicate that the electric potential gradient vector is perpendicular to the local magnetic field lines when the thruster is operating properly. The correlation between the shape of the ion beam current density and that of the ion density at the screen grid within the thruster is shown to be 94%. Additional experimental studies on maximum propellant utilization, plasma ion production cost, neutral density in the cathode discharge region, double ion production in hollow cathode thrusters and thermal flow meter performance are discussed.

Analysis of the Henze precipitate from the blood cells of the ascidian Phallusia mammillata

NASA Astrophysics Data System (ADS)

Ciancio, Aurelio; Scippa, Silvia; Nette, Geoffrey; De Vincentiis, Mario

The Henze precipitate, a peculiar blue-green microparticulate obtained by lysis of the blood cells of the ascidian Phallusia mammillata (Protochordata), was investigated with atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray microanalysis. The precipitate was collected from the Henze solution, an unstable red-brown product obtained by treating blood with distilled water, whose degradation yields a characteristic blue-green product. The microparticulates measured 50-100 µm in diameter and appeared irregular in shape. SEM examination showed smooth, roughly round boundaries. The microparticulate surface examined with AFM appeared as an irregular matrix formed by 70-320-nm-wide mammillate composites, including and embedding small (500-800 nm wide) crystal-like multilayered formations. X- ray analysis showed that the elements present in these same precipitates were mainly C, Si, Al and O. The microparticulate composition appeared close to those of natural waxes or lacquers, embedding amorphous silicates and/or other Si-Al components. The unusual occurrence of Si in ascidian blood and its role are discussed.

Introduction of atrazine degrader to enhance rhizodegradation of atrazine

USDA-ARS?s Scientific Manuscript database

Introducing atrazine (ATR) degraders into riparian vegetative buffer strips (VBS) can be a promising bioremediation approach to accelerate the degradation of ATR and its degradation products deposited into VBS by surface runoff. A growth chamber study was conducted to investigated the synergistic ef...

Effect of pharmaceutical excipients on the stability of angiotensin-converting enzyme inhibitors in their solid dosage formulations.

PubMed

Stanisz, Beata; Regulska, Katarzyna; Kania, Jagoda; Garbacki, Piotr

2013-01-01

The compatibility studies of moexipril hydrochloride (MOXL), imidapril hydrochloride (IMD), enalapril maleate, (ENA) and lisinopril (LIS) in solid state with magnesium stearate and glyceryl behenate were performed. The aim of this study was to detect any possible drug-excipient interactions in order to optimize technological process conditions by the selection of the most adequate lubricant. Reversed-phase high-performance liquid chromatography was employed for studying drug-excipient binary mixtures in 1:1 ratio and pure drugs under forced ageing test conditions: temperature 318K (45 °C) and relative humidity range of 50.9%-75.4%. The method had been revalidated prior to use. The degradation rate constants for the binary mixtures and pure substances were calculated. The experimental results evidenced that moexipril and enalapril degradation accorded with autocatalytic-second-order kinetics, imidapril degradation followed first-order reaction mechanism, and LIS followed reversible first-order reaction mechanism. A degradation pathway for each substance was proposed to account for the observed decomposition products. It was determined that moexipril stability decreased threefold in the presence of magnesium stearate indicating an incompatibility--(4.15 ± 0.12) 10(-3) compared to (1.43 ± 0.32) 10(-6) for moexipril in pure. No interaction between magnesium stearate and the remaining studied compounds was observed. The stability studies of MOXL-glyceryl behenate binary mixture revealed no interaction. Magnesium stearate and increased relative humidity induce MOXL instability, while glyceryl behenate is an optimal lubricant, and therefore, it is recommended for moexipril-containing solid formulations. However, for the formulations containing moexipril and magnesium stearate, it is suggested to minimize the humidity level during storage.

Investigating the Degradation Behaviors of a Therapeutic Monoclonal Antibody Associated with pH and Buffer Species.

PubMed

Zheng, Songyan; Qiu, Difei; Adams, Monica; Li, Jinjiang; Mantri, Rao V; Gandhi, Rajesh

2017-01-01

This study aimed in understanding the degradation behaviors of an IgG 1 subtype therapeutic monoclonal antibody A (mAb-A) associated with pH and buffer species. The information obtained in this study can augment conventional, stability-based screening paradigms by providing the direction necessary for efficient experimental design. Differential scanning calorimetry (DSC) was used for studying conformational stability. Dynamic light scattering (DLS) was utilized to generate B 22 *, a modified second virial coefficient for the character of protein-protein interaction. Size-exclusion chromatography (SEC) and hydrophobic interaction chromatography (HIC) were employed to separate degradation products. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used for determining the molecular size and liquid chromatography mass spectrometry (LC-MS) were used for identifying the sequence of the separated fragments. The results showed that both pH and buffer species played the roles in controlling the degradation behaviors of mAb-A, but the pH was more significant. In particular, pH 4.5 induced additional thermal transition peaks occurring at a low temperature compared with pH 6.5. A continual temperature-stress study illustrated that the additional thermal transition peaks related to the least stable structure and a greater fragmentation. Although mAb-A showed the comparable conformational structures and an identical amount of aggregates at time zero between the different types of buffer species at pH 6.5, the aggregation formation rate showed a buffer species-dependent discrepancy over a temperature-stress period. It was found that the levels of aggregations associated with the magnitudes of protein-protein interaction forces.

Variation of Carbohydrate-Active Enzyme Patterns in the Gut Microbiota of Italian Healthy Subjects and Type 2 Diabetes Patients.

PubMed

Soverini, Matteo; Turroni, Silvia; Biagi, Elena; Quercia, Sara; Brigidi, Patrizia; Candela, Marco; Rampelli, Simone

2017-01-01

The human gut microbiota (GM) has been associated, to date, with various complex functions, essentials for the host health. Among these, it is certainly worth noting the degradation of the so-called microbiota-accessible carbohydrates (MACs), which the GM breaks down through specific enzymes, referred to as carbohydrate-active enzymes (CAZymes). This degradation constitutes the first step in the production of short-chain fatty acids (SCFAs), key microbial small molecules having multiple health-promoting effects for the host organism. The decline in MAC dietary intake in urban Western populations forced the shrinkage of CAZyme repertoire in the GM, as shown by the literature comparing the microbiome layout between Western urban citizens and traditional rural populations. Even if this reduction in GM functional complexity has been associated with the onset of the so-called "diseases of civilization," only few information regarding the CAZyme variation within Western populations has been provided to date, and its connections with diet and health are still unexplored. In this scenario, here we explore the GM-encoded CAZyme repertoire across two Italian adult cohorts, including healthy lean subjects consuming a Mediterranean diet and obese patients affected by type 2 diabetes, consuming a high-fat diet. In order to impute the CAZyme panel, a pipeline consisting of publicly available software - QIIME, FragGeneScan and HMMER - was specifically implemented. Our study highlighted the existence of robust clusters of bacterial species sharing a common MAC degradation profile in the Italian GM, allowing the stratification of the individual GM into different steady states according to the carbohydrate degradation profile, with possible connections with diet and health.

Women's relationship with the environment.

PubMed

Davidson, J

1993-02-01

In developing countries, all development activities as well as reclamation of degraded areas, pollution reduction, and preservation of biodiversity affect women's environment, especially in rural areas. Women produce most subsistence foods and cash crops, but control only about 1% of the world's land. Lack of land tenure and of access to it keep women from obtaining credit, training, and other supports, thereby preventing them from using their traditional, longterm conservation practices. In many developing countries, commercial producers force women off the most productive lands and onto marginal lands where they grow subsistence crops. They tend to overuse the marginal land and to allow little time for soil recovery. Soil degradation is exacerbated when women need to travel greater distances to collect fuelwood, water, fodder, and food. Almost complete desertification awaits Rajasthan, India, where such events and intensive cash cropping occur. Heavy pesticide use on large commercial farms increases pest resistance, thereby boosting infestation and reducing species diversity. Women are testing sustainable agricultural techniques, for instance, interplanting and crop rotation. Even though women supply water needs, they tend to be excluded from planning, implementing, and maintaining water supplies. Women depend on forests to provide food, fodder, fuel, building materials, medicines, and many materials for income-earning efforts. Commercial logging, migration and resettlement, agricultural development, and cutting for firewood and charcoal destroy these forests. Reforestation schemes do not consider women's needs. Deforestation and desertification increase women's work burdens. Poor women who have migrated to urban areas also experience environmental degradation, deteriorating health, and resource depletion; most live in squatter settlements. Deteriorating economic circumstances in developing countries, reduced flows of official development assistance to developing countries, rapid population growth, lack of women's support mechanisms, and civil conflict are underlying factors for environmental degradation.

Micro-mechanical model for the tension-stabilized enzymatic degradation of collagen tissues

NASA Astrophysics Data System (ADS)

Nguyen, Thao; Ruberti, Jeffery

We present a study of how the collagen fiber structure influences the enzymatic degradation of collagen tissues. Experiments of collagen fibrils and tissues show that mechanical tension can slow and halt enzymatic degradation. Tissue-level experiments also show that degradation rate is minimum at a stretch level coincident with the onset of strain-stiffening in the stress response. To understand these phenomena, we developed a micro-mechanical model of a fibrous collagen tissue undergoing enzymatic degradation. Collagen fibers are described as sinusoidal elastica beams, and the tissue is described as a distribution of fibers. We assumed that the degradation reaction is inhibited by the axial strain energy of the crimped collagen fibers. The degradation rate law was calibrated to experiments on isolated single fibrils from bovine sclera. The fiber crimp and properties were fit to uniaxial tension tests of tissue strips. The fibril-level kinetic and tissue-level structural parameters were used to predict tissue-level degradation-induced creep rate under a constant applied force. We showed that we could accurately predict the degradation-induce creep rate of the pericardium and cornea once we accounted for differences in the fiber crimp structure and properties.

A test house study of pesticides and pesticide degradation products following an indoor application.

PubMed

Starr, J M; Gemma, A A; Graham, S E; Stout, D M

2014-08-01

Preexisting pesticide degradates are a concern for pesticide biomonitoring studies as exposure to them may result in overestimation of pesticide exposure. The purpose of this research was to determine whether there was significant formation and movement, of pesticide degradates over a 5-week period in a controlled indoor setting after insecticide application. Movement of the pesticides during the study was also evaluated. In a simulated crack and crevice application, commercially available formulations of fipronil, propoxur, cis/trans-permethrin, and cypermethrin were applied to a series of wooden slats affixed to the wall in one room of an unoccupied test house. Floor surface samples were collected through 35 days post-application. Concentrations of the pesticides and the following degradates were determined: 2-iso-propoxyphenol, cis/trans 3-(2,2-dichlorovinyl)-3-3-dimethyl-(1-cyclopropane) carboxylic acid, 3-phenoxybenzoic acid, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl. Deltamethrin, which had never been applied, and chlorpyrifos, which had been applied several years earlier, and their degradation products, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and, 3,5,6-trichloro-2-pyridinol, respectively, were also measured. Propoxur was the only insecticide with mass movement away from the application site. There was no measurable formation or movement of the degradates. However, all degradates were present at low levels in the formulated product. These results indicate longitudinal repetitive sampling of indoor degradate levels during short-term studies, is unnecessary. Exposure to preexisting pesticide degradates may inflate estimates of exposure in biomonitoring studies where these compounds are used as biomarkers. To date, there is no published information on formation of pesticide degradates following an indoor application. We found that the study pesticides have low rates of degradation and are unlikely to be a significant factor affecting results of short-term (weeks) biomonitoring studies. Therefore, relatively few indoor samples are needed to estimate background levels of degradation products resulting from a recent pesticide application. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Estrogen Degraders and Estrogen Degradation Pathway Identified in an Activated Sludge.

PubMed

Chen, Yi-Lung; Fu, Han-Yi; Lee, Tzong-Huei; Shih, Chao-Jen; Huang, Lina; Wang, Yu-Sheng; Ismail, Wael; Chiang, Yin-Ru

2018-05-15

The environmental release and fate of estrogens are becoming an increasing public concern. Bacterial degradation has been considered the main process for eliminating estrogens from wastewater treatment plants. Various bacterial isolates are reportedly capable of aerobic estrogen degradation, and several estrogen degradation pathways have been proposed in proteobacteria and actinobacteria. However, the ecophysiological relevance of estrogen-degrading bacteria in the environment is unclear. In this study, we investigated the estrogen degradation pathway and corresponding degraders in activated sludge collected from the Dihua Sewage Treatment Plant, Taipei, Taiwan. Cultivation-dependent and cultivation-independent methods were used to assess estrogen biodegradation in the collected activated sludge. Estrogen metabolite profile analysis revealed the production of pyridinestrone acid and two A/B-ring cleavage products in activated sludge incubated with estrone (1 mM), which are characteristic of the 4,5- seco pathway. PCR-based functional assays detected sequences closely related to alphaproteobacterial oecC , a key gene of the 4,5- seco pathway. Metagenomic analysis suggested that Novosphingobium spp. are major estrogen degraders in estrone-amended activated sludge. Novosphingobium sp. strain SLCC, an estrone-degrading alphaproteobacterium, was isolated from the examined activated sludge. The general physiology and metabolism of this strain were characterized. Pyridinestrone acid and the A/B-ring cleavage products were detected in estrone-grown strain SLCC cultures. The production of pyridinestrone acid was also observed during the aerobic incubation of strain SLCC with 3.7 nM (1 μg/liter) estrone. This concentration is close to that detected in many natural and engineered aquatic ecosystems. The presented data suggest the ecophysiological relevance of Novosphingobium spp. in activated sludge. IMPORTANCE Estrogens, which persistently contaminate surface water worldwide, have been classified as endocrine disruptors and human carcinogens. We contribute new knowledge on the major estrogen biodegradation pathway and estrogen degraders in wastewater treatment plants. This study considerably advances the understanding of environmental estrogen biodegradation, which is instrumental for the efficient elimination of these hazardous pollutants. Moreover, this study substantially improves the understanding of microbial estrogen degradation in the environment. Copyright © 2018 American Society for Microbiology.

Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing.

PubMed

Ohta, Yoichi

2017-12-01

The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s -1 , which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.

Assessing the effect of human-induced land degradation on ecosystem function in the former homelands of South Africa

NASA Astrophysics Data System (ADS)

Wessels, K. J.; Prince, S. D.

2004-12-01

The communal homelands in north-eastern South Africa, created during the apartheid-era, are widely regarded as severely degraded as a result of human utilization. The impacts of degradation on net primary production (NPP) were studied using a time-series (1985 to 2003) of Advanced Very High Resolution Radiometer (AVHRR) NDVI and modeled NPP data for degraded rangelands identified by the National Land Cover (using Landsat TM imagery) and non-degraded rangelands within the same land capability units (LCUs). The NPP of degraded areas was significantly lower than in non-degraded parts of most of the LCUs and the difference between degraded and non-degraded areas did not diminish in years with high rainfall, although NPP in degraded areas in wet years exceeded that of non-degraded areas in drier years. Thus degraded areas had the same resilience as non-degraded areas. The Rain-Use Efficiency (RUE) of degraded areas (NPP per unit rainfall) was also consistently lower than non-degraded areas. The persistence of the effect on the NPP indicated that the degradation is stable at the time scale of 18 years. These results indicate that, while there has not been a catastrophic reduction in ecosystem function within the former homelands, degradation results in a stable state with reduced productivity and RUE. The results highlight the importance of multi-temporal analyses of ecosystem function to understanding land degradation and illustrate how long time-series of terrestrial data might be used in a national land degradation monitoring system.

Sunflower Oil and Nannochloropsis oculata Microalgae as Sources of Unsaturated Fatty Acids for Mitigation of Methane Production and Enhancing Diets' Nutritive Value.

PubMed

Gomaa, Ali S; Kholif, Ahmed E; Kholif, Abdelkader M; Salama, Reda; El-Alamy, Hamza A; Olafadehan, Olurotimi A

2018-02-28

The objective of this assay was to investigate the effect of adding sunflower oil, Nannochloropsis oculata microalgae and their mixture at 0, 1, 2, 3, 4, and 5% to three total mixed rations (TMRs) with different concentrate:forage ratios (40C:60F, 50C:50F, and 60C:40F) on in vitro gas production (GP), methane (CH 4 ) production, and nutrient degradability. Asymptotic GP, GP rate, CH 4 concentration/g acid detergent fiber (ADF), dry matter (DM) degradability (DMD), short chain fatty acids (SCFAs), and ruminal bacteria population increased, but neutral detergent fiber (NDF) degradability (NDFD), ADF degradability (ADFD), and protozoa count decreased with increasing concentrate level in the TMR. Methane production/g DM and NDF was higher for 50C:50F TMR. Sunflower oil reduced asymptotic GP, lag time, CH 4 production/g ADF, ammonia-N (NH 3 -N), and SCFA. Compared to the control treatments, additives decreased GP rate, while sunflower oil/N. oculata mixture increased DMD and NDFD. All additives at 5% increased GP rate and lag time and decreased CH 4 production/g DM, ADF, and NDF, ruminal NH 3 -N, and protozoa count. All additives at 2% increased DMD, NDFD and ADFD, SCFA, and bacteria population. Supplementation of TMR, containing different concentrate:forage ratios, with sunflower oil, N. oculata, and sunflower oil/N. oculata mixture at different doses modified in vitro GP, CH 4 production, and nutrient degradability.

Potential occupational risk of amines in carbon capture for power generation.

PubMed

Gentry, P Robinan; House-Knight, Tamara; Harris, Angela; Greene, Tracy; Campleman, Sharan

2014-08-01

While CO2 capture and storage (CCS) technology has been well studied in terms of its efficacy and cost of implementation, there is limited available data concerning the potential for occupational exposure to amines, mixtures of amines, or degradation of by-products from the CCS process. This paper is a critical review of the available data concerning the potential effects of amines and CCS-degradation by-products. A comprehensive review of the occupational health and safety issues associated with exposure to amines and amine by-products at CCS facilities was performed, along with a review of the regulatory status and guidelines of amines, by-products, and CCS process vapor mixtures. There are no specific guidelines or regulations regarding permissible levels of exposure via air for amines and degradation products that could form atmospheric oxidation of amines released from post-combustion CO2 capture plants. While there has been a worldwide effort to develop legal and regulatory frameworks for CCS, none are directly related to occupational exposures. By-products of alkanolamine degradation may pose the most significant health hazard to workers in CCS facilities, with several aldehydes, amides, nitramines, and nitrosamines classified as either known or potential/possible human carcinogens. The absence of large-scale CCS facilities; absence and unreliability of reported data in the literature from pilot facilities; and proprietary amine blends make it difficult to estimate potential amine exposures and predict formation and exposure to degradation products.

Characterization of Volatile Nylon 6.6 Thermal-Oxidative Degradation Products by Selective Isotopic Labeling and Cryo-GC/MS

NASA Astrophysics Data System (ADS)

Smith, Jonell N.; V. White, Gregory; White, Michael I.; Bernstein, Robert; Hochrein, James M.

2012-09-01

Aged materials, such as polymers, can exhibit modifications to their chemical structure and physical properties, which may render the material ineffective for its intended purpose. Isotopic labeling was used to characterize low-molecular weight volatile thermal-oxidative degradation products of nylon 6.6 in an effort to better understand and predict changes in the aged polymer. Headspace gas from aged (up to 243 d at 138 °C) nylon 6.6 monomers (adipic acid and 1,6-hexanediamine) and polymer were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). Observations regarding the relative concentrations observed in each chromatographic peak with respect to aging time were used in conjunction with mass spectra for samples aged under ambient air to determine the presence and identity of 18 degradation products. A comparison of the National Institute of Standards and Technology (NIST) library, unlabeled, and isotopically labeled mass spectra (C-13 or N-15) and expected fragmentation pathways of each degradation product were used to identify the location of isotopically labeled atoms within the product's chemical structure, which can later be used to determine the exact origin of the species. In addition, observations for unlabeled nylon 6.6 aged in an O-18 enriched atmosphere were used to determine if the source of oxygen in the applicable degradation products was from the gaseous environment or the polymer. Approximations for relative isotopic ratios of unlabeled to labeled products are reported, where appropriate.

Identification, synthesis and structural characterization of process related and degradation impurities of acrivastine and validation of HPLC method.

PubMed

Kumar, Ajay; Devineni, Subba Rao; Dubey, Shailender Kumar; Kumar, Pradeep; Srivastava, Vishal; Ambulgekar, Girish; Jain, Mohit; Gupta, Dharmendra Kumar; Singh, Gurmeet; Kumar, Rajesh; Hiriyanna, S G; Kumar, Pramod

2016-10-17

Four impurities (Imp-I-IV) were detected using gradient HPLC method in few laboratory batches of acrivastine in the level of 0.03-0.12% and three impurities (Imp-I-III) were found to be known and one (Imp-IV) was unknown. In forced degradation study, the drug is degraded into four degradation products under oxidation and photolytic conditions. Two impurities (Imp-III and -IV) were concurred with process related impurities whereas Imp-V and -VI were identified as new degradation impurities. Based on LC-ESI/MS n study, the chemical structures of new impurities were presumed as 1-[(2E)-3-(4-methylphenyl)-3-{6-[(1E)-3-oxobut-1-en-1-yl]pyridin-2-yl}prop-2-en-1-yl]pyrrolidin-1-ium-1-olate (Imp-IV), 1-{[3-(4-methylphenyl)-3-{6-[(1E)-3-oxobut-1-en-1-yl]pyridin-2-yl}oxiran-2-yl]methyl}pyrrolidin-1-ium-1-olate (Imp-V) and 2-[2-(4-methylphenyl)-3-[(1-oxidopyrrolidin-1-ium-1-yl)methyl]oxiran-2-yl]-6-[(1E)-3-oxobut-1-en-1-yl]pyridin-1-ium-1-olate (Imp-VI), and confirmed by their synthesis followed by spectroscopic analysis, IR, NMR ( 1 H, 13 C) and mass. An efficient and selective high-performance liquid chromatography method has been developed and resolved well the drug related substances on a Phenomenex Gemini C-18 (250×4.6mm, particle size 5μm) column. The mobile phase was composed of sodium dihydrogen phosphate (10mM) and methanol, temperature at 25°C, and a PDA detector set at 254nm used for detection. The method was validated with respect to specificity, linearity, precision, accuracy, and sensitivity and satisfactory results were achieved. Identification, synthesis, characterization of impurities and method validation were first reported in this paper. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular imprinted hydrogel polymer (MIHP) as microbial immobilization media in artificial produced water treatment

NASA Astrophysics Data System (ADS)

Kardena, E.; Ridhati, S. L.; Helmy, Q.

2018-01-01

Produced water generated during oil and gas exploration and drilling, consists of many chemicals which used in drilling process. The production of produced water is over three fold of the oil production. The water-cut has increased over time and continues to do so because the fraction of oil in the reservoir decreases and it is more difficult to get the oil out from an old oil-field. It therefore requires more sea water to be injected in order to force the oil out; hence more produced water is generated. Produced water can pollute the environment if it is not treated properly. In this research, produced water will be treated biologically using bacterial consortium which is isolated from petroleum processing facility with Molecular Imprinted Hydrogel Polymer (MIHP) for microbial immobilization media. Microbial growth rate is determined by measuring the MLVSS and hydrogel mass, also by SEM-EDS analysis. SEM-EDS analysis is an analysis to evidence the presence of microbe trapped in hydrogel, and also to determine the types and weight of the molecules of hydrogel. From this research, suspended microbial growth rate was found at 0.1532/days and attached microbial growth rate was 0.3322/days. Furthermore, based on SEM analysis, microbe is entrapped inside the hydrogel. Effectiveness of microbial degradation activity was determined by measuring organic materials as COD. Based on COD measurement, degradation rate of organic materials in wastewater is 0.3089/days, with maximum COD removal efficiency of 76.67%.

Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

NASA Technical Reports Server (NTRS)

Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

1992-01-01

The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

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

PubMed

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.

Triggerable Degradation of Polyurethanes for Tissue Engineering Applications.

PubMed

Xu, Cancan; Huang, Yihui; Wu, Jinglei; Tang, Liping; Hong, Yi

2015-09-16

Tissue engineered and bioactive scaffolds with different degradation rates are required for the regeneration of diverse tissues/organs. To optimize tissue regeneration in different tissues, it is desirable that the degradation rate of scaffolds can be manipulated to comply with various stages of tissue regeneration. Unfortunately, the degradation of most degradable polymers relies solely on passive controlled degradation mechanisms. To overcome this challenge, we report a new family of reduction-sensitive biodegradable elastomeric polyurethanes containing various amounts of disulfide bonds (PU-SS), in which degradation can be initiated and accelerated with the supplement of a biological product: antioxidant-glutathione (GSH). The polyurethanes can be processed into films and electrospun fibrous scaffolds. Synthesized materials exhibited robust mechanical properties and high elasticity. Accelerated degradation of the materials was observed in the presence of GSH, and the rate of such degradation depends on the amount of disulfide present in the polymer backbone. The polymers and their degradation products exhibited no apparent cell toxicity while the electrospun scaffolds supported fibroblast growth in vitro. The in vivo subcutaneous implantation model showed that the polymers prompt minimal inflammatory responses, and as anticipated, the polymer with the higher disulfide bond amount had faster degradation in vivo. This new family of polyurethanes offers tremendous potential for directed scaffold degradation to promote maximal tissue regeneration.

Biotransformation of geosmin by terpene-degrading bacteria.

USDA-ARS?s Scientific Manuscript database

Two terpene-degrading bacteria that are able to transform geosmin have been identified. Pseudomonas sp. SBR3-tpnb, isolated on -terpinene, converts geosmin to several products; the major products are keto-geosmins. This geosmin transformation ability is inducible by -terpinene. Rhodococcus wratisl...

The impact of substrate stiffness and mechanical loading on fibroblast-induced scaffold remodeling.

PubMed

Petersen, Ansgar; Joly, Pascal; Bergmann, Camilla; Korus, Gabriela; Duda, Georg N

2012-09-01

Fibroblasts as many other cells are known to form, contract, and remodel the extracellular matrix (ECM). The presented study aims to gain an insight into how mechanical boundary conditions affect the production of ECM components, their remodeling, and the feedback of the altered mechanical cell environment on these processes. The influence of cyclic mechanical loading (f=1 Hz, 10% axial compression) and scaffold stiffness (E=1.2 and 8.5 kPa) on the mechanical properties of fibroblast-seeded scaffold constructs were investigated in an in vitro approach over 14 days of culture. To do so, a newly developed bioreactor system was employed. While mechanical loading resulted in a clear upregulation of procollagen-I and fibronectin production, scaffold stiffness showed to primarily influence matrix metalloproteinase-1 (MMP-1) secretion and cell-induced scaffold contraction. Higher stiffness of the collagen scaffolds resulted in an up to twofold higher production of collagen-degrading MMP-1. The changes of mechanical parameters like Young's modulus, maximum compression force, and elastic portion of compression force over time suggest that from initially distinct mechanical starting conditions (scaffold stiffness), the construct's mechanical properties converge over time. As a consequence of mechanical loading a shift toward higher construct stiffness was observed. The results suggest that scaffold stiffness has only a temporary effect on cell behavior, while the impact of mechanical loading is preserved over time. Thus, it is concluded that the mechanical environment of the cell after remodeling is depending on mechanical loading rather than on initial scaffold stiffness.

Adaptation of the Conditions of US EPA Method 538 for the ...

EPA Pesticide Factsheets

Report The objective of this study was to evaluate U.S. EPA’s Method 538 for the assessment of drinking water exposure to the nerve agent degradation product, EA2192, the most toxic degradation product of nerve agent VX. As a result of the similarities in sample preparation and analysis that Method 538 uses for nonvolatile chemicals, this method is applicable to the nonvolatile Chemical Warfare Agent (CWA) degradation product, EA2192, in drinking water. The method may be applicable to other nonvolatile CWAs and their respective degradation products as well, but the method will need extensive testing to verify compatibility. Gaps associated with the need for analysis methods capable of analyzing such analytes were addressed by adapting the EPA 538 method for this CWA degradation product. Many laboratories have the experience and capability to run the already rigorous method for nonvolatile compounds in drinking water. Increasing the number of laboratories capable of carrying out these methods serves to significantly increase the surge laboratory capacity to address sample throughput during a large exposure event. The approach desired for this study was to start with a proven high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) method for nonvolatile chemicals in drinking water and assess the inclusion of a similar nonvolatile chemical, EA2192.

Investigation of relationships between removals of tetracycline and degradation products and physicochemical parameters in municipal wastewater treatment plant.

PubMed

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.

Chlorination kinetics of glyphosate and its by-products: modeling approach.

PubMed

Brosillon, Stephan; Wolbert, Dominique; Lemasle, Marguerite; Roche, Pascal; Mehrsheikh, Akbar

2006-06-01

Chlorination reactions of glyphosate, glycine, and sodium cyanate were conducted in well-agitated reactors to generate experimental kinetic measurements for the simulation of chlorination kinetics under the conditions of industrial water purification plants. The contribution of different by-products to the overall degradation of glyphosate during chlorination has been identified. The kinetic rate constants for the chlorination of glyphosate and its main degradation products were either obtained by calculation according to experimental data or taken from published literature. The fit of the kinetic constants with experimental data allowed us to predict consistently the concentration of the majority of the transitory and terminal chlorination products identified in the course of the glyphosate chlorination process. The simulation results conducted at varying aqueous chlorine/glyphosate molar ratios have shown that glyphosate is expected to degrade in fraction of a second under industrial aqueous chlorination conditions. Glyphosate chlorination products are not stable under the conditions of drinking water chlorination and are degraded to small molecules common to the degradation of amino acids and other naturally occurring substances in raw water. The kinetic studies of the chlorination reaction of glyphosate, together with calculations based on kinetic modeling in conditions close to those at real water treatment plants, confirm the reaction mechanism that we have previously suggested for glyphosate chlorination.

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection.

PubMed

Richardson, Douglas D; Caruso, Joseph A

2007-06-01

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC-ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC-time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC-ICPMS.

Isolation and characterization of Halomonas sp. strain C2SS100, a hydrocarbon-degrading bacterium under hypersaline conditions.

PubMed

Mnif, S; Chamkha, M; Sayadi, S

2009-09-01

To isolate and characterize an efficient hydrocarbon-degrading bacterium under hypersaline conditions, from a Tunisian off-shore oil field. Production water collected from 'Sercina' petroleum reservoir, located near the Kerkennah island, Tunisia, was used for the screening of halotolerant or halophilic bacteria able to degrade crude oil. Bacterial strain C2SS100 was isolated after enrichment on crude oil, in the presence of 100 g l(-1) NaCl and at 37 degrees C. This strain was aerobic, Gram-negative, rod-shaped, motile, oxidase + and catalase +. Phenotypic characters and phylogenetic analysis based on the 16S rRNA gene of the isolate C2SS100 showed that it was related to members of the Halomonas genus. The degradation of several compounds present in crude oil was confirmed by GC-MS analysis. The use of refined petroleum products such as diesel fuel and lubricating oil as sole carbon source, under the same conditions of temperature and salinity, showed that significant amounts of these heterogenic compounds could be degraded. Strain C2SS100 was able to degrade hexadecane (C16). During growth on hexadecane, cells surface hydrophobicity and emulsifying activity increased indicating the production of biosurfactant by strain C2SS100. A halotolerant bacterial strain Halomonas sp. C2SS100 was isolated from production water of an oil field, after enrichment on crude oil. This strain is able to degrade hydrocarbons efficiently. The mode of hydrocarbon uptake is realized by the production of a biosurfactant which enhances the solubility of hydrocarbons and renders them more accessible for biodegradation. The biodegradation potential of the Halomonas sp. strain C2SS100 gives it an advantage for possibly application on bioremediation of water, hydrocarbon-contaminated sites under high-salinity level.

Degradation of the herbicide 2, 4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt by gamma radiation from cobalt-60 in aqueous solution containing humic acid

NASA Astrophysics Data System (ADS)

Campos, Sandro X.; Vieira, Eny M.; Cordeiro, Paulo J. M.; Rodrigues-Fo, Edson; Murgu, Michael

2003-12-01

In this study, gamma radiation from cobalt-60 was used to degrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) dimethylamine salt in water in the presence of humic acid. The 2,4-D dimethylamine salt 1.13×10 -4 mol dm -3 solution was irradiated with different doses. HPLC was used as an analytical technique to determine the degradation rate of herbicide studied. The results showed that the herbicide was completely degraded at an absorbed dose of 3 kGy. Degradation decreased when humic acid was added to all the doses. ESI/MS and MS/MS were used to identify the radiolytic degradation products. A fragmentation path for production of 4.6-dichlororesorcinol, is suggested. The radiolytic yields ( G) were calculated.

Interactions between F-111 Fuselage Fuel Tank Sealants. Part I. Characterisation of Polyester Sealants and their Hydrolytic Degradation Products,

DTIC Science & Technology

1983-12-01

maleic acid , adipic acid , azelaic acid and suberic acid . To ensure complete esterification during the exhaustive degradation reactions, an...spectroscopic techniques. Major components were shown to be sebacic acid and neopentyl glycol. The most significant difference between the two polyester...and acid equivalent weights of the prepolymers, their hydrolysis products and hydrolysed cured sealants were determined to assess extent of degradation

Absence of Degradation of Tretinoin When Benzoyl Peroxide is Combined with an Optimized Formulation of Tretinoin Gel (0.05%)

PubMed Central

Pillai, Radhakrishnan; Moore, Robert

2010-01-01

Background: Clinicians have been reluctant to prescribe benzoyl peroxide concurrently with topical tretinoin due to a belief that the benzoyl peroxide may cause oxidation and degradation of the tretinoin molecule, thereby reducing its effectiveness. However, benzoyl peroxide-induced degradation of tretinoin may not necessarily apply to all topical tretinoin formulations. Objective: To evaluate the potential for benzoyl peroxide-induced degradation of an optimized aqueous gel formulation of tretinoin (0.05%). Methods: Tretinoin gel (0.05%) and benzoyl peroxide gel (6.26% premix concentration to produce 5% benzoyl peroxide in a fixed combination clindamycin product) were mixed together (1:1) at 32ºC and samples assayed after 1, 2, 3, 5, and 7 hours. Each sample was analyzed for tretinoin (expressed as % tretinoin remaining) and its degradation product content. Results: No loss of tretinoin was observed over the seven-hour time period. When tretinoin gel (0.05%) was combined with benzoyl peroxide, 100 percent of the initial tretinoin concentration remained after seven hours. There was no increase in the degradation products of tretinoin. Conclusions: There was no benzoyl peroxide-induced degradation of tretinoin when the optimized formulation of tretinoin gel (0.05%) was admixed with benzoyl peroxide gel (6.26%). Although the direct clinical significance of these results is unknown, clinicians may feel comfortable using this particular combination concurrently without concerns about tretinoin oxidation and degradation. PMID:20967192

[Ligninolytic enzyme production by white rot fungi during paraquat (herbicide) degradation].

PubMed

Camacho-Morales, Reyna L; Gerardo-Gerardo, José Luis; Guillén Navarro, Karina; Sánchez, José E

Paraquat is a widely used herbicide in agriculture. Its inappropriate use and wide distribution represents a serious pollution problem for soil and water. White rot fungi are capable of degrading pollutants having a similar structure to that of lignin, such as paraquat. This study evaluated the degradation effect of paraquat on the production of ligninolytic enzymes by white rot fungi isolated from the South of Mexico. Six fungal strains showed tolerance to the herbicide in solid culture. Three of the six evaluated strains showed levels of degradation of 32, 26 and 47% (Polyporus tricholoma, Cilindrobasidium laeve and Deconica citrispora, respectively) after twelve days of cultivation in the presence of the xenobiotic. An increase in laccase and manganese peroxidase (MnP) activities was detected in the strains showing the highest percentage of degradation. Experiments were done with enzyme extracts from the extracellular medium with the two strains showing more degradation potential and enzyme production. After 24hours of incubation, a degradation of 49% of the initial paraquat concentration was observed for D. citrispora. These results suggest that paraquat degradation can be attributed to the presence of extracellular enzymes from white rot fungi. In this work the first evidence of the biodegradation potential of D. citrispora and Cilindrobasidium leave is shown. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

NASA Astrophysics Data System (ADS)

Lorah, Michelle M.; Voytek, Mary A.

2004-05-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, Michelle M.; Voytek, Mary A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction.Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: Biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, M.M.; Voytek, M.A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Influence of the temperature and oxygen exposure in red Port wine: A kinetic approach.

PubMed

Oliveira, Carla Maria; Barros, António S; Silva Ferreira, António César; Silva, Artur M S

2015-09-01

Although phenolics are recognized to be related with health benefits by limiting lipid oxidation, in wine, they are the primary substrates for oxidation resulting in the quinone by-products with the participation of transition metal ions. Nevertheless, high quality Port wines require a period of aging in either bottle or barrels. During this time, a modification of sensory properties of wines such as the decrease of astringency or the stabilization of color is recognized to phenolic compounds, mainly attributed to anthocyanins and derived pigments. The present work aims to illustrate the oxidation of red Port wine based on its phenolic composition by the effect of both thermal and oxygen exposures. A kinetic approach toanthocyanins degradation was also achieved. For this purpose a forced red Port wine aging protocol was performed at four different storage temperatures, respectively, 20, 30, 35 and 40°C, and two adjusted oxygen saturation levels, no oxygen addition (treatment I), and oxygen addition (treatment II). Three hydroxycinnamic esters, three hydroxycinnamic acids, three hydroxybenzoic acids, two flavan-3-ols, and six anthocyanins were quantitated weekly during 63days, along with oxygen consumption. The most relevant phenolic oxidation markers were anthocyanins and catechin-type flavonoids, which had the highest decreases during the thermal and oxidative red Port wine process. Both temperature and oxygen treatments affected the rate of phenolic degradation. In addition, temperature seems to influence mostly the phenolics kinetic degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evidence of polyethylene biodegradation by bacterial strains from the guts of plastic-eating waxworms.

PubMed

Yang, Jun; Yang, Yu; Wu, Wei-Min; Zhao, Jiao; Jiang, Lei

2014-12-02

Polyethylene (PE) has been considered nonbiodegradable for decades. Although the biodegradation of PE by bacterial cultures has been occasionally described, valid evidence of PE biodegradation has remained limited in the literature. We found that waxworms, or Indian mealmoths (the larvae of Plodia interpunctella), were capable of chewing and eating PE films. Two bacterial strains capable of degrading PE were isolated from this worm's gut, Enterobacter asburiae YT1 and Bacillus sp. YP1. Over a 28-day incubation period of the two strains on PE films, viable biofilms formed, and the PE films' hydrophobicity decreased. Obvious damage, including pits and cavities (0.3-0.4 μm in depth), was observed on the surfaces of the PE films using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of carbonyl groups was verified using X-ray photoelectron spectroscopy (XPS) and microattenuated total reflectance/Fourier transform infrared (micro-ATR/FTIR) imaging microscope. Suspension cultures of YT1 and YP1 (10(8) cells/mL) were able to degrade approximately 6.1 ± 0.3% and 10.7 ± 0.2% of the PE films (100 mg), respectively, over a 60-day incubation period. The molecular weights of the residual PE films were lower, and the release of 12 water-soluble daughter products was also detected. The results demonstrated the presence of PE-degrading bacteria in the guts of waxworms and provided promising evidence for the biodegradation of PE in the environment.

Ascorbate degradation in tomato leads to accumulation of oxalate, threonate and oxalyl threonate.

PubMed

Truffault, Vincent; Fry, Stephen C; Stevens, Rebecca G; Gautier, Hélène

2017-03-01

Ascorbate content in plants is controlled by its synthesis from carbohydrates, recycling of the oxidized forms and degradation. Of these pathways, ascorbate degradation is the least studied and represents a lack of knowledge that could impair improvement of ascorbate content in fruits and vegetables as degradation is non-reversible and leads to a depletion of the ascorbate pool. The present study revealed the nature of degradation products using [ 14 C]ascorbate labelling in tomato, a model plant for fleshy fruits; oxalate and threonate are accumulated in leaves, as is oxalyl threonate. Carboxypentonates coming from diketogulonate degradation were detected in relatively insoluble (cell wall-rich) leaf material. No [ 14 C]tartaric acid was found in tomato leaves. Ascorbate degradation was stimulated by darkness, and the degradation rate was evaluated at 63% of the ascorbate pool per day, a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more. Furthermore, degradation could be partially affected by the ascorbate recycling pathway, as lines under-expressing monodehydroascorbate reductase showed a slight decrease in degradation product accumulation. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Kinetics and pathways of ibuprofen degradation by the UV/chlorine advanced oxidation process.

PubMed

Xiang, Yingying; Fang, Jingyun; Shang, Chii

2016-03-01

The UV/chlorine advanced oxidation process (AOP), which forms reactive species such as hydroxyl radicals (HO) and reactive chlorine species (RCS) such as chlorine atoms (Cl) and Cl2(-), is being considered as an alternative to the UV/H2O2 AOP for the degradation of emerging contaminants. This study investigated the kinetics and pathways of the degradation of a recalcitrant pharmaceutical and personal care product (PPCP)-ibuprofen (IBP)-by the UV/chlorine AOP. The degradation of IBP followed the pseudo first-order kinetics. The first-order rate constant was 3.3 times higher in the UV/chlorine AOP than in the UV/H2O2 AOP for a given chemical molar dosage at pH 6. The first-order rate constant decreased from 3.1 × 10(-3) s(-1) to 5.5 × 10(-4) s(-1) with increasing pH from 6 to 9. Both HO and RCS contributed to the degradation, and the contribution of RCS increased from 22% to 30% with increasing pH from 6 to 9. The degradation was initiated by HO-induced hydroxylation and Cl-induced chlorine substitution, and sustained through decarboxylation, demethylation, chlorination and ring cleavage to form more stable products. Significant amounts of chlorinated intermediates/byproducts were formed from the UV/chlorine AOP, and four chlorinated products were newly identified. The yield of total organic chlorine (TOCl) was 31.6 μM after 90% degradation of 50 μM IBP under the experimental conditions. The known disinfection by-products (DBPs) comprised 17.4% of the TOCl. The effects of water matrix in filtered drinking water on the degradation were not significant, demonstrating the practicality of the UV/chlorine AOP for the control of some refractory PPCPs. However, the toxicity of the chlorinated products should be further assessed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Personnel Security during Joint Operations with Foreign Military Forces

DTIC Science & Technology

2013-08-01

century society into the twenty-first century encounters a number of obstacles. Illiteracy and innumeracy rates are high, and repressive social values are...warfare. In 1978 the communist-backed PDPA assassi- nated Mohammad Daoud and implemented sweeping but ill-conceived social reforms. Afghan civilians were...Operations with Foreign Military Forces Feature quickly degraded into executions for social infractions like blasphemy. Repression soon followed, and the

Determination of early warning signs for photocatalytic degradation of titanium white oil paints by means of surface analysis

NASA Astrophysics Data System (ADS)

van Driel, B. A.; Wezendonk, T. A.; van den Berg, K. J.; Kooyman, P. J.; Gascon, J.; Dik, J.

2017-02-01

Titanium white (TiO2) has been widely used as a pigment in the 20th century. However, its most photocatalytic form (anatase) can cause severe degradation of the oil paint in which it is contained. UV light initiates TiO2-photocatalyzed processes in the paint film, degrading the oil binder into volatile components resulting in chalking of the paint. This will eventually lead to severe changes in the appearance of a painting. To date, limited examples of degraded works of art containing titanium white are known due to the relatively short existence of the paintings in question and the slow progress of the degradation process. However, UV light will inevitably cause degradation of paint in works of art containing photocatalytic titanium white. In this work, a method to detect early warning signs of photocatalytic degradation of unvarnished oil paint is proposed, using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Consequently, a four-stage degradation model was developed through in-depth study of TiO2-containing paint films in various stages of degradation. The XPS surface analysis proved very valuable for detecting early warning signs of paint degradation, whereas the AFM results provide additional confirmation and are in good agreement with bulk gloss reduction.

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.

PubMed

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 preliminary separation.

Biodegradation of photo-oxidized lignite and characterization of the products

NASA Astrophysics Data System (ADS)

Li, Jiantao; Liu, Xiangrong; Yue, Zilin; Zhang, Yaowen

2018-01-01

Biodegradation of photo-oxidized Inner Mongolia lignite by pseudomonas aeruginosa was studied and the degradation percentage reached 56.27%, while the corresponding degradation percentage of the strain degrading raw Inner Mongolia lignite is only 23.16%. The degradation products were characterized. Proximate and ultimate analyses show that the higher oxygen content increased by photo-oxidation pretreatment maybe promoted the degradation process. Ultraviolet spectroscopy (UV) analysis of the liquid product reveals that it contains unsaturated structures and aromatic rings are the main structure units. Gas chromatography-mass spectrometry (GC-MS) analysis indicates that the main components of the ethyl acetate extracts are low molecular weight organic compounds, such as ketones, acids, hydrocarbons, esters and alcohols. Infrared spectroscopy (IR) analysis of raw lignite, photo-oxidized lignite and residual lignite demonstrates that the absorption peaks of functional groups in residual lignite disappeared or weakened obviously. Scanning electron microscopy (SEM) analysis manifests that small holes appear in photo-oxidized lignite surface, which may be promote the degradation process and this is only from the physical morphology aspects, so it can be inferred from the tests and analyses results that the more important reason of the high degradation percentage is mostly that the photo-oxidation pretreatment changes the chemical structures of lignite.

Effect of Fe(III) on 1,1,2,2-tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the Aberdeen proving ground

USGS Publications Warehouse

Jones, E.J.P.; Voytek, M.A.; Lorah, M.M.

2004-01-01

1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek, MD, where dechlorination occurred. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways led to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The effect of adding Fe(III) to TeCA-amended microcosms of wetland sediment was studied. Differences were identified in the TeCA degradation pathway between microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated microcosms than no AFO microcosms. The microcosm incubations and subsequent experiments with the microcosm materials showed that AFO treatment resulted in lower production of VC by shifting TeCA degradation from dichloroelimination pathways to production of a greater proportion of chlorinated ethane products, and decreasing the microbial capability to produce VC from 1,2-dichloroethylene. VC degradation was not stimulated in the presence of Fe(III). Rather, VC degradation occurred readily under methanogenic conditions and was inhibited under Fe(III)-reducing conditions.

Nanobiocatalytic Degradation of Acid Orange 7

NASA Astrophysics Data System (ADS)

Hastings, Jason

The catalytic properties of various metal nanoparticles have led to their use in environmental remediation applications. However, these remediation strategies are limited by their ability to deliver catalytic nanoparticles and a suitable electron donor to large treatment zones. Clostridium pasteurianum BC1 cells, loaded with bio-Pd nanoparticles, were used to effectively catalyze the reductive degradation and removal of Acid Orange 7 (AO7), a model azo compound. Hydrogen produced fermentatively by the C. pasteurianum BC1 acted as the electron donor for the process. Pd-free bacterial cultures or control experiments conducted with heat-killed cells showed limited reduction of AO7. Experiments also showed that the in situ biological production of H2 by C. pasteurianum BC1 was essential for the degradation of AO7, which suggests a novel process where the in situ microbial production of hydrogen is directly coupled to the catalytic bio-Pd mediated reduction of AO7. The differences in initial degradation rate for experiments conducted using catalyst concentrations of 1ppm Pd and 5ppm Pd and an azo dye concentration of 100ppm AO7 was 0.39 /hr and 1.94 /hr respectively, demonstrating the importance of higher concentrations of active Pd(0). The degradation of AO7 was quick as demonstrated by complete reductive degradation of 50ppm AO7 in 2 hours in experiments conducted using a catalyst concentration of 5ppm Pd. Dye degradation products were analyzed via Gas Chromatograph-Mass Spectrometer (GCMS), High Performance Liquid Chromatography (HPLC), UltraViolet-Visible spectrophotometer (UV-Vis) and Matrix-Assisted Laser Desorption/Ionization (MALDI) spectrometry. The presence of 1-amino 2-naphthol, one of the hypothesized degradation products, was confirmed using mass spectrometry.

Oxidative degradation of organic acids conjugated with sulfite oxidation in flue gas desulfurization

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

Lee, Y.I.

Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (EGD) conditions. The oxidative degradation constant, k/sub 12/, is defined as the ratio of organic acid degradation rate and sulfite oxidation rate after being normalized by the concentrations of organic acid and dissolved S(IV). K/sub 12/, not significantly affected by pH or dissolved oxygen, is around 10/sup -3/ in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Co, Ni, and Fe and is decreased by Mn and halides. Lower dissolved S(IV) magnified these effects. No k/sub 12/more » greater than 4 x 10/sup -3/ or smaller than 0.1 x 10/sup -3/ has been observed. A free radical mechanism was proposed to describe the kinetics: (1) sulfate free radical is the major radical responsible to the degradation of organic acid; (2) ferrous generates sulfate radical by reacting with monoxypersulfate to enhance k/sub 12/; (3) manganous consumes sulfate radical to decrease k/sub 12/; (4) dissolved S(IV) competes with ferrous for monoxypersulfate and with manganous for sulfate radical to demonstrate the effects of dissolved S(IV) on k/sub 12/. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product, glutaric semialdehyde - the major retained product with low manganese, glutaric acid and valeric acids - the major retained product with high manganese, lower molecular weight mono- and dicarboxylic acids, other carbonyl compounds, and hydrocarbons.« less

Insight into the Mechanism of Graphene Oxide Degradation via the Photo-Fenton Reaction

PubMed Central

2015-01-01

Graphene represents an attractive two-dimensional carbon-based nanomaterial that holds great promise for applications such as electronics, batteries, sensors, and composite materials. Recent work has demonstrated that carbon-based nanomaterials are degradable/biodegradable, but little work has been expended to identify products formed during the degradation process. As these products may have toxicological implications that could leach into the environment or the human body, insight into the mechanism and structural elucidation remain important as carbon-based nanomaterials become commercialized. We provide insight into a potential mechanism of graphene oxide degradation via the photo-Fenton reaction. We have determined that after 1 day of treatment intermediate oxidation products (with MW 150–1000 Da) were generated. Upon longer reaction times (i.e., days 2 and 3), these products were no longer present in high abundance, and the system was dominated by graphene quantum dots (GQDs). On the basis of FTIR, MS, and NMR data, potential structures for these oxidation products, which consist of oxidized polycyclic aromatic hydrocarbons, are proposed. PMID:24860637

Optical Detection of Degraded Therapeutic Proteins.

PubMed

Herrington, William F; Singh, Gajendra P; Wu, Di; Barone, Paul W; Hancock, William; Ram, Rajeev J

2018-03-23

The quality of therapeutic proteins such as hormones, subunit and conjugate vaccines, and antibodies is critical to the safety and efficacy of modern medicine. Identifying malformed proteins at the point-of-care can prevent adverse immune reactions in patients; this is of special concern when there is an insecure supply chain resulting in the delivery of degraded, or even counterfeit, drug product. Identification of degraded protein, for example human growth hormone, is demonstrated by applying automated anomaly detection algorithms. Detection of the degraded protein differs from previous applications of machine-learning and classification to spectral analysis: only example spectra of genuine, high-quality drug products are used to construct the classifier. The algorithm is tested on Raman spectra acquired on protein dilutions typical of formulated drug product and at sample volumes of 25 µL, below the typical overfill (waste) volumes present in vials of injectable drug product. The algorithm is demonstrated to correctly classify anomalous recombinant human growth hormone (rhGH) with 92% sensitivity and 98% specificity even when the algorithm has only previously encountered high-quality drug product.

[Environmental behavior and ecological effect of polydimethylsiloxane: a review].

PubMed

Yang, Shang-Yuan; Li, Xin; Yang, Jia; Shen, Chao-Feng; Yu, Hua-Dong; Lu, Kang

2012-08-01

Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used.

Gamma-radiolytic stability of new methylated TODGA derivatives for minor actinide recycling

DOE PAGES

Galan, Hitos; Zarzana, Christopher A.; Wilden, Andreas; ...

2015-09-15

The stability against gamma radiation of MeTODGA (methyl tetraoctyldiglycolamide) and Me2TODGA (dimethyl tetraoctyldiglycolamide), derivatives from the well-known extractant TODGA (N,N,N',N';-tetraoctyldiglycolamide), were studied and compared. Solutions of MeTODGA and Me2TODGA in alkane diluents were subjected to 60Co γ-irradiation in the presence and absence of nitric acid and analyzed using LC-MS to determine their rates of radiolytic concentration decrease, as well as to identify radiolysis products. The results of product identification from three different laboratories are compared and found to be in good agreement. The diglycolamide (DGA) concentrations decreased exponentially with increasing absorbed dose. The MeTODGA degradation rate constants (dose constants) weremore » uninfluenced by the presence of nitric acid, but the acid increased the rate of degradation for Me2TODGA. The degradation products formed by irradiation are also initially produced in greater amounts in acid-contacted solution, but products may also be degraded by continued radiolysis. As a result, the identified radiolysis products suggest that the weakest bonds are those in the diglycolamide center of these molecules.« less

Development and application of a validated stability-indicating HPLC method for simultaneous determination of granisetron hydrochloride, benzyl alcohol and their main degradation products in parenteral dosage forms.

PubMed

Hewala, Ismail; El-Fatatre, Hamed; Emam, Ehab; Mubrouk, Mokhtar

2010-06-30

A simple, rapid and sensitive reversed phase high performance liquid chromatographic method using photodiode array detection was developed and validated for the simultaneous determination of granisetron hydrochloride, benzyl alcohol, 1-methyl-1H-indazole-3-carboxylic acid (the main degradation product of granisetron) and benzaldehyde (the main degradation product of benzyl alcohol) in granisetron injections. The separation was achieved on Hypersil BDS C8 (250 mm x 4.6 mm i.d., 5 microm particle diameter) column using a mobile phase consisted of acetonitrile:0.05 M KH(2)PO(4):triethylamine (22:100:0.15) adjusted to pH 4.8. The column was maintained at 25 degrees C and 20 microL of solutions was injected. Photodiode array detector was used to test the peak purity and the chromatograms were extracted at 210 nm. Naphazoline hydrochloride was used as internal standard. The method was validated with respect to specificity, linearity, accuracy, precision, limit of quantitation and limit of detection. The validation acceptance criteria were met in all cases. Identification of the pure peaks was carried out using library match programmer and wavelengths of derivative optima of the spectrograms of the peaks. The method was successfully applied to the determination of the investigated drugs and their degradation products in different batches of granisetron injections. The method was proved to be sensitive for the determination down to 0.03 and 0.01% of granisetron degradation product and benzaldehyde, respectively, which are far below the compendia limits for testing these degradation products in their corresponding intact drugs. Copyright 2010 Elsevier B.V. All rights reserved.

[Degradation Kinetics and Formation of Disinfection By-products During Linuron Chlorination in Drinking Water].

PubMed

Ling, Xiao; Hu, Chen-yan; Cheng, Ming; Gu, Jian

2015-05-01

Chlorination degradation of linuron was studied using the common disinfectant sodium hypochlorite, the effects of chlorine dosage, pH value, bromine ion concentrationand temperature were systematically investigated, and the formation characteristics of disinfection by-products (DBPs) during the chlorination reaction was analyzed. The results showed that the chlorination degradation kinetics of linuron by sodium hypochlorite could be well described by the second-order kinetic model. Moreover, pH values had a great impact on the degradation reaction, and the rate constant reached the maximum level at pH 7, and the base elementary reaction rate constants of HOCl and OCl- with linuron were 4.84 x 10(2) L · (mol · h)(-1) and 3.80 x 10(2) L · (mol · h)(-1), respectively. The reaction rate decreased with the addition of bromide ion and increased with increasing temperature. Furthermore, many kinds of disinfection by- products were produced during the chlorination degradation of linuron, including CF, DCAN, TCNM and halogen acetone. Under conditions of different solution pH and different bromide ion concentrations, there would be significant difference in the types and concentrations of disinfection by-products.

Characteristics of liquid product from the pyrolysis of waste plastic mixture at low and high temperatures: influence of lapse time of reaction.

PubMed

Lee, Kyong-Hwan; Shin, Dae-Hyun

2007-01-01

Pyrolysis of a waste plastic mixture (high-density polyethylene: low-density polyethylene: polypropylene: polystyrene = 3:2:3:1) into a liquid product was carried out in a stirred semi-batch reactor at low (350 degrees C) and high (400 degrees C) temperatures. The effect of lapse time of reaction in the reactor and also degradation temperature on the characteristics of the liquid product from pyrolysis of the mixture was investigated. Liquid products were described by cumulative amount distribution, paraffin, olefin, naphthene and aromatic (PONA) distribution and molecular weight distribution. Their characteristic was quite differed with a lapse time of reaction and also at a low and high degradation temperatures, because of the different physicochemical properties of the plastic types in the mixture. With increase of lapse time of reaction, the order for the main products in PONA components obtained at 350 degrees C was firstly aromatic products and then olefin products, while at 400 degrees C the order was firstly aromatic products, then olefin products and finally paraffin products. The experiments also showed from the molecular weight distribution of liquid PONA components that the paraffin and olefin products had a wide distribution by mainly random scission of polymer, but in the case of olefin products were produced by an end-chain scission mechanism as well as random scission mechanism, as evidenced by much more light olefin products. This phenomenon was evident at a higher degradation temperature. Also, both the light olefin and naphthene products with a molecular weight of around 120, as a main product, showed a similar trend as a function of lapse time, which had a maximum fraction at 343 min (at 350 degrees C) and 83 min (at 400 degrees C). Among PONA components, the highest concentrations of aromatic products were obtained with a molecular weight of around 100 at the fastest lapse time of reaction, regardless of degradation temperature. It was concluded that the characteristics of liquid product on the pyrolysis of plastic mixtures were strongly influenced by lapse time of reaction and degradation temperature.

Biological studies on the degradation products of 3-[(S)-1'-phenylethylamino]propylaminobleomycin: a novel analog (pepleomycin).

PubMed

Takahashi, K; Ekimoto, H; Aoyagi, S; Koyu, A; Kuramochi, H; Yoshioka, O; Matsuda, A; Fujii, A; Umezawa, H

1979-01-01

Pepleomycin (PEP), 3-[(S)-1'-phenylethylamino]propylaminobleomycin has potent activity and is less pulmonary toxic than bleomycin (BLM). Biological activity and toxicity of the following degradation products of PEP have been studied in detail: the product of carbamoyl migration (ISO), the product of decarbamylation (DC), the product of ring closure of the side chain on the pyrimidine moiety (RC), the depyruvamide product (DP) and the product of an enzymatic inactivation (DA). These degradation products showed much lower activity than PEP in vitro: antimicrobial and anti-HeLa activities, inhibition of DNA synthesis in AH66 cells and the DNA strand cleavage. Acute toxicity and pulmonary toxicity were tested in mice. Results indicated much lower acute toxicity corresponding to the decreased in vitro activity when compared to PEP. DP and RC did not cause lung fibrosis in mice, while ISO and DC showed 1/2.6 and 1/5.7 degree of pulmonary toxicity, respectively, in comparison with PEP.

Effect of sleep deficit, knowledge of results, and stimulus quality on reaction time and response force.

PubMed

Jaśkowski, P; Włodarczyk, D

1997-04-01

Some recent findings suggested that response force measured during reaction time experiments might reflect changes in activation. We performed an experiment in which the effect of sleep deprivation, knowledge of results, and stimulus quality on response force was studied in simple and choice reaction tasks. As expected, both simple and choice reaction times increased with sleep deficit. Further, simple and choice reactions were faster with knowledge of results and slowed down when stimulus quality was degraded. As sleep deprivation affects both arousal and activation, we expected a detrimental effect of sleep on force amplitude. On the other hand, knowledge of results was expected to increase force by its compensatory effect on arousal and activation. No effect of sleep deprivation on response force was found. Knowledge of results increased response force independently of sleep deprivation.

Effect of two non-synonymous ecto-5'-nucleotidase variants on the genetic architecture of inosine 5'-monophosphate (IMP) and its degradation products in Japanese Black beef.

PubMed

Uemoto, Yoshinobu; Ohtake, Tsuyoshi; Sasago, Nanae; Takeda, Masayuki; Abe, Tsuyoshi; Sakuma, Hironori; Kojima, Takatoshi; Sasaki, Shinji

2017-11-13

Umami is a Japanese term for the fifth basic taste and is an important sensory property of beef palatability. Inosine 5'-monophosphate (IMP) contributes to umami taste in beef. Thus, the overall change in concentration of IMP and its degradation products can potentially affect the beef palatability. In this study, we investigated the genetic architecture of IMP and its degradation products in Japanese Black beef. First, we performed genome-wide association study (GWAS), candidate gene analysis, and functional analysis to detect the causal variants that affect IMP, inosine, and hypoxanthine. Second, we evaluated the allele frequencies in the different breeds, the contribution of genetic variance, and the effect on other economical traits using the detected variants. A total of 574 Japanese Black cattle were genotyped using the Illumina BovineSNP50 BeadChip and were then used for GWAS. The results of GWAS showed that the genome-wide significant single nucleotide polymorphisms (SNPs) on BTA9 were detected for IMP, inosine, and hypoxanthine. The ecto-5'-nucleotidase (NT5E) gene, which encodes the enzyme NT5E for the extracellular degradation of IMP to inosine, was located near the significant region on BTA9. The results of candidate gene analysis and functional analysis showed that two non-synonymous SNPs (c.1318C > T and c.1475 T > A) in NT5E affected the amount of IMP and its degradation products in beef by regulating the enzymatic activity of NT5E. The Q haplotype showed a positive effect on IMP and a negative effect on the enzymatic activity of NT5E in IMP degradation. The two SNPs were under perfect linkage disequilibrium in five different breeds, and different haplotype frequencies were seen among breeds. The two SNPs contribute to about half of the total genetic variance in IMP, and the results of genetic relationship between IMP and its degradation products showed that NT5E affected the overall concentration balance of IMP and its degradation products. In addition, the SNPs in NT5E did not have an unfavorable effect on the other economical traits. Based on all the above findings taken together, two non-synonymous SNPs in NT5E would be useful for improving IMP and its degradation products by marker-assisted selection in Japanese Black cattle.

Biodegradation of the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) by purified pentachlorophenol hydroxylase and whole cells of Flavobacterium sp. strain ATCC 39723 is accompanied by cyanogenesis.

PubMed Central

Topp, E; Xun, L Y; Orser, C S

1992-01-01

A pentachlorophenol (PCP)-degrading Flavobacterium sp. (strain ATCC 39723) degraded bromoxynil with the production of bromide and cyanide. No aromatic intermediates were detected in the spent culture fluid. The cyanide produced upon bromoxynil metabolism was inhibitory to the Flavobacterium sp. Whole cells degraded PCP more rapidly than they did bromoxynil. Bromoxynil metabolism and PCP metabolism were coinduced, either substrate serving as the inducer. Purified PCP hydroxylase degraded bromoxynil with stoichiometric accumulation of cyanide and without bromide production. A product accumulated which was more hydrophilic than bromoxynil upon high-pressure liquid chromatographic analysis and which, when analyzed by gas chromatography-mass spectrometry, had a mass spectrum consistent with that expected for dibromohydroquinone. PCP hydroxylase consumed NADPH, oxygen, and bromoxynil in a 2:1:1 molar ratio, producing 1 mol of cyanide per mol of bromoxynil degraded. We propose a pathway by which bromoxynil is metabolized by the same enzymes which degrade PCP. The initial step in the pathway is the conversion of bromoxynil to 2,6-dibromohydroquinone by PCP hydroxylase. In addition to its utility for decontaminating PCP-polluted sites, the Flavobacterium sp. may be useful for decontaminating bromoxynil spills. This is the first report of cyanide production accompanying the metabolism of a benzonitrile derivative. PMID:1610174

Chemical Composition, In vitro Gas Production, Ruminal Fermentation and Degradation Patterns of Diets by Grazing Steers in Native Range of North Mexico

PubMed Central

Murillo, M.; Herrera, E.; Carrete, F. O.; Ruiz, O.; Serrato, J. S.

2012-01-01

The objective of the study was to quantify annual and seasonal differences in the chemical composition, in vitro gas production, in situ degradability and ruminal fermentation of grazing steers’ diets. Diet samples were collected with four esophageal cannulated steers (350±3 kg BW); and four ruminally cannulated heifers (342±1.5 kg BW) were used to study the dry matter degradation and fermentation in rumen. Data were analyzed with repeated measurements split plot design. The crude protein, in vitro dry matter digestibility and metabolizable energy were higher during the first year of trial and in the summer (p<0.01). The values of calcium, phosphorus, magnesium, zinc and copper were higher in summer (p<0.05). The gas produced by the soluble and insoluble fractions, as well as the constant rate of gas production were greater in summer and fall (p<0.01). The ammonia nitrogen (NH3N) and total volatile fatty acids concentrations in rumen, the soluble and degradable fractions, the constant rate of degradation and the effective degradability of DM and NDF were affected by year (p<0.05) and season (p<0.01). Our study provides new and useful knowledge for the formulation of protein, energetic and mineral supplements that grazing cattle need to improve their productive and reproductive performance. PMID:25049495

From ether to acid: A plausible degradation pathway of glycerol dialkyl glycerol tetraethers

NASA Astrophysics Data System (ADS)

Liu, Xiao-Lei; Birgel, Daniel; Elling, Felix J.; Sutton, Paul A.; Lipp, Julius S.; Zhu, Rong; Zhang, Chuanlun; Könneke, Martin; Peckmann, Jörn; Rowland, Steven J.; Summons, Roger E.; Hinrichs, Kai-Uwe

2016-06-01

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39 and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80 to C82 tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.

Anaerobic degradation of inedible crop residues produced in a Controlled Ecological Life Support System

NASA Technical Reports Server (NTRS)

Schwingel, W. R.; Sager, J. C.

1996-01-01

An anaerobic reactor seeded with organisms from an anaerobic lagoon was used to study the degradation of inedible crop residues from potato and wheat crops grown in a closed environment. Conversion of this biomass into other products was also evaluated. Degradation of wheat volatile solids was about 25% where that of potato was about 50%. The main product of the anaerobic fermentation of both crops was acetic acid with smaller quantities of propionate and butyrate produced. Nitrate, known to be high in concentration in inedible potato and wheat biomass grown hydroponically, was converted to ammonia in the anaerobic reactor. Both volatile fatty acid and ammonia production may have implications in a crop production system.

Influence of diet on growth yields of rumen micro-organisms in vitro and in vivo: influence on growth yield of variable carbon fluxes to fermentation products.

PubMed

Blümmel, M; Karsli, A; Russell, J R

2003-09-01

The efficiency of rumen microbial production (EMP) in vitro and in vivo was examined for three roughages (lucerne (Medicago sativa L.) hay, oat (Avenia sativa L.)-berseem clover (Trifolium alexandrinum cultivar BigBee) hay and maize (Zea mays L.) crop residue (MCR)) and for five isonitrogenous (106 g crude protein (Nx6.25)/kg) diets formulated from lucerne hay, oat-berseem clover hay, MCR, soybean meal and maize grain to provide degradable intake protein for the production of 130 g microbial protein/kg total digestible nutrients. EMP in vivo was determined by intestinal purine recovery in sheep and ranged from 240 to 360 g microbial biomass/kg organic matter truly degraded in MCR and in one of the diets respectively (P<0.05). EMP in vitro was estimated by the substrate degraded : gas volume produced thereby (termed partitioning factor, PF (mg/ml)) at times of estimated peak microbial production and after 16.0 and 24.0 h of incubation. For the diets, PF values were significantly related to EMP in vivo at peak microbial production (P=0.04), but not after 16.0 (P=0.08) and 24.0 h (P=0.66). For roughages, PF values were significantly related to EMP in vivo only when measured after 16.0 h (P=0.04). For MCR and diets, a close non-linear relationship was found between PF values at peak microbial production and EMP in vivo (R(2) 0.99, P<0.0001) suggesting a maximum EMP in vivo of 0.39. Low gas production per unit substrate degraded (high PF) was associated with high EMP in vivo. The in vitro study of the products of fermentation, short-chain fatty acids, gases and microbial biomass (by purine analysis) after 16.0 h of incubation showed very strong relationships (R(2)> or =0.89, P<0.0001) between short-chain fatty acids, gases and gravimetrically measured apparent degradability. Except for maize grain, the true degradability of organic matter estimated by neutral-detergent solution treatment agreed with the sum of the products of fermentation (R(2) 0.81, P=0.0004). After 16.0 h of incubation, the synergistic effects of diet ingredient on diets were greater for microbial biomass (18 %) than for short-chain fatty acids and gas production (7 %). It is concluded that measurement of gas production only gives incomplete information about fodder quality; complementation of gas measurements by true degradability measurements is recommended.

Improving methane production from digested manure biofibers by mechanical and thermal alkaline pretreatment.

PubMed

Tsapekos, P; Kougias, Panagiotis G; Frison, A; Raga, R; Angelidaki, I

2016-09-01

Animal manure digestion is associated with limited methane production, due to the high content in fibers, which are hardly degradable lignocellulosic compounds. In this study, different mechanical and thermal alkaline pretreatment methods were applied to partially degradable fibers, separated from the effluent stream of biogas reactors. Batch and continuous experiments were conducted to evaluate the efficiency of these pretreatments. In batch experiments, the mechanical pretreatment improved the degradability up to 45%. Even higher efficiency was shown by applying thermal alkaline pretreatments, enhancing fibers degradability by more than 4-fold. In continuous experiments, the thermal alkaline pretreatment, using 6% NaOH at 55°C was proven to be the most efficient pretreatment method as the methane production was increased by 26%. The findings demonstrated that the methane production of the biogas plants can be increased by further exploiting the fraction of the digested manure fibers which are discarded in the post-storage tank. Copyright © 2016 Elsevier Ltd. All rights reserved.

Two Synthetic Methods for Preparation of Chiral Stationary Phases Using Crystalline Degradation Products of Vancomycin: Column Performance for Enantioseparation of Acidic and Basic Drugs.

PubMed

Abdollahpour, Assem; Heydari, Rouhollah; Shamsipur, Mojtaba

2017-07-01

Two chiral stationary phases (CSPs) based on crystalline degradation products (CDPs) of vancomycin by using different synthetic methods were prepared and compared. Crystalline degradation products of vancomycin were produced by hydrolytic loss of ammonia from vancomycin molecules. Performances of two chiral columns prepared with these degradation products were investigated using several acidic and basic drugs as model analytes. Retention and resolution of these analytes on the prepared columns, as two main parameters, in enantioseparation were studied. The results demonstrated that the stationary phase preparation procedure has a significant effect on the column performance. The resolving powers of prepared columns for enantiomers resolution were changed with the variation in vancomycin-CDP coverage on the silica support. Elemental analysis was used to monitor the surface coverage of silica support by vancomycin-CDP. The results showed that both columns can be successfully applied to chiral separation studies.

Role of litter turnover in soil quality in tropical degraded lands of Colombia.

PubMed

León, Juan D; Osorio, Nelson W

2014-01-01

Land degradation is the result of soil mismanagement that reduces soil productivity and environmental services. An alternative to improve degraded soils through reactivation of biogeochemical nutrient cycles (via litter production and decomposition) is the establishment of active restoration models using new forestry plantations, agroforestry, and silvopastoral systems. On the other hand, passive models of restoration consist of promoting natural successional processes with native plants. The objective in this review is to discuss the role of litter production and decomposition as a key strategy to reactivate biogeochemical nutrient cycles and thus improve soil quality in degraded land of the tropics. For this purpose the results of different projects of land restoration in Colombia are presented based on the dynamics of litter production, nutrient content, and decomposition. The results indicate that in only 6-13 years it is possible to detect soil properties improvements due to litter fall and decomposition. Despite that, low soil nutrient availability, particularly of N and P, seems to be major constraint to reclamation of these fragile ecosystems.

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

PubMed

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.

Thermal degradation events as health hazards - Particle vs gas phase effects, mechanistic studies with particles

NASA Technical Reports Server (NTRS)

Oberdoerster, G.; Ferin, J.; Finkelstein, J.; Soderholm, S.

1992-01-01

Experiments on animal subjects are performed to demonstrate that significant lung injury can result from the inhalation of ultrafine TiO2 or Al2O3 particles. The methods include intratracheal instillation of particles, long-term inhalation of particles, and in vitro studies of alveolar macrophages (AMs) to study the production of fibroplast growth factors. The ultrafine TiO2 particles are shown to induce more acute inflammatory reactions than larger particles and lead to persistent chronic effects in the AM-mediated clearance function of particles. The ultrafine particles also induce cytokines more readily, and the data generally suggests that the occurrence of such particles in thermal degradation events makes the fumes highly toxic. The exposure to thermal degradation products is therefore a critical concern for manned space missions with potentially degradable plastic products.

Chemical Degradation of the Cathodic Electrical Contact Between Carbon and Cast Iron in Aluminum Production Cells

NASA Astrophysics Data System (ADS)

Brassard, Martin; Désilets, Martin; Soucy, Gervais; Bilodeau, Jean-François; Forté, Martin

2017-06-01

The cathodic carbon to cast iron electrical contact degradation is one of the factors to consider in the cathode voltage drop (CVD) increase over the lifetime of aluminum production cells. Lab-scale experiments were carried out to study the cast iron to carbon interface chemical degradation and the impact of important cell parameters like temperature and bath chemistry. Laboratory degradation results were compared with industrial samples. A thermoelectric Ansys numerical model was then used to predict the effect of cast iron surface degradation over CVD. Results show that the aluminum formation on the cast iron surface and its subsequent diffusion creates an immiscible mixture of Fe-Al metal alloy and electrolytic bath. Disparities were also observed between industrial samples taken from two different technologies, suggesting that the degradation can be slowed down. Thermoelectric calculations finally revealed that the impact of the contact resistance augmentation is by far greater than the cast iron degradation.

Postproduction Handling and Administration of Protein Pharmaceuticals and Potential Instability Issues.

PubMed

Nejadnik, M Reza; Randolph, Theodore W; Volkin, David B; Schöneich, Christian; Carpenter, John F; Crommelin, Daan J A; Jiskoot, Wim

2018-04-14

The safety and efficacy of protein pharmaceuticals depend not only on biological activity but also on purity levels. Impurities may be process related because of limitations in manufacturing or product related because of protein degradation occurring throughout the life history of a product. Although the pharmaceutical biotechnology industry has made great progress in improving bulk and drug product manufacturing as well as company-controlled storage and transportation conditions to minimize the level of degradation, there is less control over the many factors that may subsequently affect product quality after the protein pharmaceuticals are released and shipped by the manufacturer. Routine handling or unintentional mishandling of therapeutic protein products may cause protein degradation that remains unnoticed but can potentially compromise the clinical safety and efficacy of the product. In this commentary, we address some potential risks associated with (mis)handling of protein pharmaceuticals after release by the manufacturer. We summarize the environmental stress factors that have been shown to cause protein degradation and that may be encountered during typical handling procedures of protein pharmaceuticals in a hospital setting or during self-administration by patients. Moreover, we provide recommendations for improvements in product handling to help ensure the quality of protein pharmaceuticals during use. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

WEATHERABILITY OF ENHANCED DEGRADABLE PLASTICS

EPA Science Inventory

The main objective of this study was to assess the performance and the asociated variability of several selected enhanced degradable plastic materials under a variety of different exposure conditions. Other objectives were to identify the major products formed during degradation ...

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group : determination of triazine and phenylurea herbicides and their degradation products in water using solid-phase extraction and liquid chromatography/mass spectrometry

USGS Publications Warehouse

Lee, Edward Alan; Strahan, Alex P.; Thurman, Earl Michael

2002-01-01

An analytical method for the determination of 7 triazine and phenylurea herbicides and 12 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is presented in this report. Special consideration was given during the development of the method to prevent the formation of degradation products during the analysis. Filtered water samples were analyzed using 0.5 gram graphitized carbon as the solid-phase extraction media followed by liquid chromatography/mass spectrometry. Three different water-sample matrices?ground-water, surface-water, and reagent-water samples?spiked at 0.2 and 2.0 micrograms per liter were analyzed. Method detection limits ranged from 0.013 to 0.168 microgram per liter for the parent triazine herbicides and the triazine degradation products. Method detection limits ranged from 0.042 to 0.141 microgram per liter for the parent phenylurea herbicides and their degradation products. Mean recoveries for the triazine compounds in the ground- and surface-water samples generally ranged from 72.6 to 117.5 percent, but deethyl-cyanazine amide was recovered at 140.5 percent. Mean recoveries from the ground- and surface-water samples for the phenylurea compounds spiked at the 2.0-micrograms-per-liter level ranged from 82.1 to 114.4 percent. The mean recoveries for the phenylureas spiked at 0.2-microgram per liter were less consistent, ranging from 87.0 to 136.0 percent. Mean recoveries from reagent-water samples ranged from 87.0 to 109.5 percent for all compounds. The triazine compounds and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter, with the exception of deethylcyanazine and deethylcyanazine amide which are reported at 0.20 to 2.0 micrograms per liter. The phenylurea compounds and their degradation products are reported in concentrations ranging from 0.20 to 2.0 micrograms per liter. The upper concentration limit was 2.0 micrograms per liter for all compounds without dilution.

Radiolytic degradation scheme for 60Co-irradiated corticosteroids

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

Kane, M.P.; Tsuji, K.

The cobalt 60 radiolytic degradation products have been identified in the following corticosteroids: cortisone, cortisone acetate, hydrocortisone, hydrocortisone acetate, hydrocortisone sodium succinate, isoflupredone acetate, methylprednisolone, methylprednisolone acetate, prednisolone, prednisolone acetate, and prednisone. Two major types of degradation processes have been identified: loss of the corticoid side chain on the D-ring to produce the C-17 ketone and conversion of the C-11 alcohol, if present, to the C-11 ketone. Minor degradation products derived from other changes affecting the side chain are also identified in several corticosteroids. These compounds are frequently associated in corticosteroids as process impurities or degradation compounds. No new radiolyticmore » compounds unique to 60Co-irradiation have been found. The majority of corticosteroids have been shown to be stable to 60Co-irradiation. The rates of radiolytic degradation ranged from 0.2 to 1.4%/Mrad.« less

Effect of trace metals and sulfite oxidation of adipic acid degradation in FGD systems. Final report Dec 81-May 82

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

Jarvis, J.B.; Terry, J.C.; Schubert, S.A.

The report gives results of the measurement of the adipic acid degradation rate in a bench-scale flue gas desulfurization (FGD) system, designed to simulate many of the important aspects of full-scale FGD systems. Results show that the adipic acid degradation rate depends on the sulfite oxidation rate, the adipic acid concentration, the presence of manganese in solution, and temperature. The degradation rate is also affected by pH, but only when manganese is present. Adipic acid degradation products identified in the liquid phase include valeric, butyric, propionic, succinic, and glutaric acids. When manganese was present, the predominant degradation products were succinicmore » and glutaric acids. Analysis of solids from the bench scale tests shows large concentrations of coprecipitated adipic acid in low oxidation sulfite solids. By contrast, low quantities of coprecipitated adipic acid were found in high oxidation gypsum solids.« less

Identification of pesticide transformation products in food by liquid chromatography/time-of-flight mass spectrometry via "fragmentation-degradation" relationships.

PubMed

García-Reyes, Juan F; Molina-Díaz, Antonio; Fernandez-Alba, Amadeo R

2007-01-01

The identification of transformation products of pesticides in foodstuffs is a crucial task difficult to tackle, due to the lack of standards and scarce information available. In this work, we describe a methodology for the identification and structural elucidation of pesticide transformation products in food. The proposed strategy is based on the use of liquid chromatography electrospray time-of-flight mass spectrometry (LC/TOFMS): accurate mass measurements of (molecule and fragment) ions of interest are used in order to establish relationships between fragmentation of the parent pesticides in the instrument (in-source CID fragmentation) and possible degradation products of these pesticides in food. Examples of this strategy showing the potential of LC/TOFMS to determine unknown pesticides in food are described in two different real samples, suggesting that pesticides often are transformed into degradation products in the same fashion that they are fragmented in the instrument. Using the proposed approach and without using standards a priori, based solely on accurate mass measurements of ions and "fragmentation-degradation" relationships, we have identified two parent pesticides (amitraz and malathion) along with six degradation products, m/z 253 (N,N'-bisdimethylphenylformamidine), 163 (N-2,4-dimethylphenyl-N-methyl formamidine), 150 (2,4-dimethylformamidine), and 122 (2,4-dimethylaniline) from amitraz, and m/z 317 and 303, due to ether hydrolysis of methyl and ethyl groups from malathion. Structures for these species were proposed, and the potential of the proposed approach was critically discussed.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of degradation products after treatment of methylene blue aqueous solution with three-dimensionally integrated microsolution plasma

NASA Astrophysics Data System (ADS)

Shirafuji, Tatsuru; Nomura, Ayano; Hayashi, Yui; Tanaka, Kenji; Goto, Motonobu

2016-01-01

Methylene blue can be degraded in three-dimensionally integrated microsolution plasma. The degradation products have been analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry to understand the degradation mechanisms. The results of MALDI TOF mass spectrometry have shown that sulfoxide is formed at the first stage of the oxidation. Then, partial oxidation proceeds on the methyl groups left on the sulfoxide. The sulfoxide is subsequently separated to two benzene derivatives. Finally, weak functional groups are removed from the benzene derivatives.

Persistence assessment of cyclohexyl- and norbornyl-derived ketones and their degradation products in different OECD screening tests.

PubMed

Seyfried, M; van Ginkel, C G; Boschung, A; Miffon, F; Fantini, P; Tissot, E; Baroux, L; Merle, P; Chaintreau, A

2015-07-01

The persistence of synthetic cyclohexyl- and norbornyl-derived ketones was assessed by using OECD 301F and 301D biodegradation tests. While cyclohexyl-derived ketones either reached or came close to the pass level (60%) after 60 d, the corresponding norbornyl derivatives yielded significantly less biodegradation (<40%). By analyzing extracts at 60 d, the key degradation products of four norbornyl derivatives were identified. Consistently, 2-bicyclo[2.2.1]heptane carboxylic acid was found as a principal degradation product with minor quantities of bicyclo[2.2.1]heptan-2-one and 2-bicyclo[2.2.1]heptane acetic acid. When the three degradation products were re-synthesized and tested individually for biodegradability, the former two were found to be ultimately biodegradable after 60 d in OECD 301D tests, thus proving non-persistence. Similarly, 2-bicyclo[2.2.1]heptane acetic acid was found to be degraded significantly, albeit with long lag phases exceeding 60 d in the case of freshwater inoculum, then ultimately reaching the pass level. On the other hand, norbornyl ketones were still only partially biodegradable in the same test. We conclude that despite the potential for ultimate biodegradation of norbornyl-derived ketones, current screening tests yield an incomplete picture of their biodegradability, particularly when applying strict OECD criteria. The appearance of long lag phases when re-testing norbornyl ketone degradation products underlines the importance of extending tests to well beyond 28 and even 60 d in the case of freshwater inocula. Copyright © 2015 Elsevier Ltd. All rights reserved.

Application of isotopic labeling, and gas chromatography mass spectrometry, to understanding degradation products and pathways in the thermal-oxidative aging of Nylon 6.6

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

White, Gregory Von; Clough, Roger L.; Hochrein, James M.

2013-12-01

Nylon 6.6 containing 13C isotopic labels at specific positions along the macromolecular backbone has been subjected to extensive thermal-oxidative aging at 138 °C for time periods up to 243 days. In complementary experiments, unlabeled Nylon 6.6 was subjected to the same aging conditions under an atmosphere of 18O 2. Volatile organic degradation products were analyzed by cryofocusing gas chromatography mass spectrometry (cryo-GC/MS) to identify the isotopic labeling. The labeling results, combined with basic considerations of free radical reaction chemistry, provided insights to the origin of degradation species, with respect to the macromolecular structure. A number of inferences on chemical mechanismsmore » were drawn, based on 1) the presence (or absence) of the isotopic labels in the various products, 2) the location of the isotope within the product molecule, and 3) the relative abundance of products as indicated by large differences in peak intensities in the gas chromatogram. The overall degradation results can be understood in terms of free radical pathways originating from initial attacks on three different positions along the nylon chain which include hydrogen abstraction from: the (CH 2) group adjacent to the nitrogen atom, at the (CH 2) adjacent the carbonyl group, and direct radical attack on the carbonyl. Understanding the pathways which lead to Nylon 6.6 degradation ultimately provides new insight into changes that can be leveraged to detect and reduce early aging and minimize problems associated with material degradation.« less

Development of RP-HPLC, Stability Indicating Method for Degradation Products of Linagliptin in Presence of Metformin HCl by Applying 2 Level Factorial Design; and Identification of Impurity-VII, VIII and IX and Synthesis of Impurity-VII.

PubMed

Jadhav, Sushant B; Reddy, P Sunil; Narayanan, Kalyanaraman L; Bhosale, Popatrao N

2017-06-27

The novel reverse phase-high performance liquid chromatography (RP-HPLC), stability indicating method was developed for determination of linagliptin (LGP) and its related substances in linagliptin and metformin HCl (MET HCl) tablets by implementing design of experiment to understand the critical method parameters and their relation with critical method attributes; to ensure robustness of the method. The separation of nine specified impurities was achieved with a Zorbax SB-Aq 250 × 4.6 mm, 5 µm column, using gradient elution and a detector wavelength of 225 nm, and validated in accordance with International Conference on Harmonization (ICH) guidelines and found to be accurate, precise, reproducible, robust, and specific . The drug was found to be degrading extensively in heat, humidity, basic, and oxidation conditions and was forming degradation products during stability studies. After slight modification in the buffer and the column, the same method was used for liquid chromatography-mass spectrometry (LC-MS) and ultra-performance liquid chromatography -time-of-flight/mass spectrometry UPLC-TOF/MS analysis, to identify m/z and fragmentation of maximum unspecified degradation products i.e., Impurity-VII ( 7 ), Impurity-VIII ( 8 ), and Impurity-IX ( 9 ) formed during stability studies. Based on the results, a degradation pathway for the drug has been proposed and synthesis of Impurity-VII ( 7 ) is also discussed to ensure an in-depth understanding of LGP and its related degradation products and optimum performance during the lifetime of the product.

Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts

PubMed Central

Iram, Wajiha; Anjum, Tehmina; Iqbal, Mazhar; Ghaffar, Abdul; Abbas, Mateen; Khan, Abdul Muqeet

2016-01-01

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 μg L-1 and AFB2; 50 μg L-1) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82–87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins. PMID:27471501

76 FR 42709 - Submission for OMB Review; Prohibition on Acquisition of Products Produced by Forced or...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-19

... on Acquisition of Products Produced by Forced or Indentured Child Labor AGENCY: Department of Defense... acquisition of products produced by forced or indentured child labor. DATES: Submit comments on or before... on Acquisition of Products Produced by Forced or Indentured Child Labor, by any of the following...

76 FR 24025 - Information Collection; Prohibition on Acquisition of Products Produced by Forced or Indentured...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-29

... Acquisition of Products Produced by Forced or Indentured Child Labor AGENCY: Department of Defense (DOD... acquisition of products produced by forced or indentured child labor. DATES: Submit comments on or before..., Prohibition on Acquisition of Products Produced by Forced or Indentured Child Labor, signed by the President...

How Does a Modern Field Artillery Cannon Battalion Operate in a Degraded, Denied, and Disrupted Space Operating Environment

DTIC Science & Technology

2017-06-09

reports, a potential solution to communication shortfalls was the use of high frequency (HF) Harris radios that possess complex encryption... communications , positioning, and navigation do not properly function, is known as a Degraded, Denied, Disrupted Space Operating Environment (D3SOE).7...battalion operates in a D3SOE. This was a very relevant question for a force increasingly reliant on frequency modulated (FM) radio communication systems

In Situ Biological Treatment Test at Kelly Air Force Base. Volume 2. Field Test Results and Cost Model.

DTIC Science & Technology

1987-07-01

degradation of organic contaminants. In situ treatment affects contaminants sorbed to soil as well as dissolved in groundwater. It is potentially ...indigenous soil micro - organisms to multiply and degrade the waste material. Exxon’s Baytown refinery has been disposing of oily wastes by land farming...Group (ERG). Chemical analyses performed on soil samples included priority pollutant volatile and metal compounds, total hydrocarbons (alkanes), oil and

Biocide Runoff from Building Facades: Degradation Kinetics in Soil.

PubMed

Bollmann, Ulla E; Fernández-Calviño, David; Brandt, Kristian K; Storgaard, Morten S; Sanderson, Hans; Bester, Kai

2017-04-04

Biocides are common additives in building materials. In-can and film preservatives in polymer-resin render and paint, as well as wood preservatives are used to protect facade materials from microbial spoilage. Biocides leach from the facade material with driving rain, leading to highly polluted runoff water (up to several mg L -1 biocides) being infiltrated into the soil surrounding houses. In the present study the degradation rates in soil of 11 biocides used for the protection of building materials were determined in laboratory microcosms. The results show that some biocides are degraded rapidly in soil (e.g., isothiazolinones: T 1/2 < 10 days) while others displayed higher persistence (e.g., terbutryn, triazoles: T 1/2 ≫ 120 days). In addition, mass balances of terbutryn and octylisothiazolinone were determined, including nine (terbutryn) and seven (octylisothiazolinone) degradation products, respectively. The terbutryn mass balance could be closed over the entire study period of 120 days and showed that relative persistent metabolites were formed, while the mass balances for octylisothiazolinone could not be closed. Octylisothiazolinone degradation products did not accumulate over time suggesting that the missing fraction was mineralized. Microtox-tests revealed that degradation products were less toxic toward the bacterium Aliivibrio fischeri than their parent compounds. Rain is mobilizing these biocides from the facades and transports them to the surrounding soils; thus, rainfall events control how often new input to the soil occurs. Time intervals between rainfall events in Northern Europe are shorter than degradation half-lives even for many rapidly degraded biocides. Consequently, residues of some biocides are likely to be continuously present due to repeated input and most biocides can be considered as "pseudo-persistent"-contaminants in this context. This was verified by (sub)urban soil screening, where concentrations of up to 0.1 μg g -1 were detected for parent compounds as well as terbutryn degradation products in soils below biocide treated facades.

Tretinoin Photostability

PubMed Central

Harper, Julie; Pillai, Radhakrishnan; Moore, Robert

2012-01-01

Background: Various formulations of tretinoin (gel, liquid, cream) have been reported to be unstable on the skin under bright artificial light or sunlight. This photodegradation can potentially influence treatment regimens and possibly modify efficacy. The maximum light energy absorption of tretinoin is in the ultraviolet A region. Objective: To compare the photostability of a micronized formulation of tretinoin (0.05%) aqueos gel with tretinoin (0.025%) gel following exposure to ultraviolet A light for eight hours. Methods: Micronized tretinoin (0.05%) gel and tretinoin (0.025%) gel were then exposed to ultraviolet A light with an integrated intensity from 315 to 400nm of 22watt/m2. Samples of both products were prepared and analyzed for tretinoin and its degradation products using a high-performance liquid chromatography method. Additional duplicate samples were similarly prepared and analyzed after 2,4,6, and 8 hours. Results: There was a nine-percent degradation of micronized tretinoin in the 0.05% aqueous gel compared to 72-percent degradation of tretinoin in the 0.025% gel following eight-hour ultraviolet A light exposure. The small increase in tretinoin degradation products with micronized tretinoin (0.05%) aqueous gel remained below six percent of the labeled concentration compared to a marked increase in tretinoin degradation products with tretinoin 0.025% gel at two hours that increased to over 66-percent labeled concentration at eight hours. Conclusion: Micronized tretinoin (0.05%) aqueous gel showed less than 10-percent degradation when exposed to eight hours of ultraviolet A light, while tretinoin (0.025%) gel showed significant tretinoin degradation. PMID:22328956

Time course of degradation of cardiac troponin I in patients with acute ST-elevation myocardial infarction: the ASSENT-2 troponin substudy.

PubMed

Madsen, Lene H; Christensen, Geir; Lund, Terje; Serebruany, Victor L; Granger, Chris B; Hoen, Ingvild; Grieg, Zanina; Alexander, John H; Jaffe, Allan S; Van Eyk, Jennifer E; Atar, Dan

2006-11-10

Although measurement of troponin is widely used for diagnosing acute myocardial infarction (AMI), its diagnostic potential may be increased by a more complete characterization of its molecular appearance and degradation in the blood. The aim of this study was to define the time course of cardiac troponin I (cTnI) degradation in patients with acute ST-elevation myocardial infarction (STEMI). In the ASSENT-2 substudy, 26 males hospitalized with STEMI were randomized to 2 different thrombolytic drugs within 6 hours after onset of symptoms. Blood samples were obtained just before initiation of thrombolysis and at 30 minutes intervals (7 samples per patient). Western blot analysis was performed using anti-cTnI antibodies and compared with serum concentrations of cTnI. All patients exceeded the cTnI cutoff for AMI during the sampling period; at initiation of therapy, 23 had elevated cTnI values. All patients demonstrated 2 bands on immunoblot: intact cTnI and a single degradation product as early as 90 minutes after onset of symptoms. On subsequent samples, 15 of 26 patients showed multiple degradation products with up to 7 degradation bands. The appearance of fragments was correlated with higher levels of cTnI (P<0.001) and time to initiation of treatment (P=0.058). This study defines for the first time the initial time course of cTnI degradation in STEMI. Intact cTnI and a single degradation product were detectable on immunoblot as early as 90 minutes after onset of symptoms with further degradation after 165 minutes. Infarct size and time to initiation of treatment was the major determinant for degradation.

48 CFR 22.1503 - Procedures for acquiring end products on the List of Products Requiring Contractor Certification...

Code of Federal Regulations, 2010 CFR

2010-10-01

... end products on the List of Products Requiring Contractor Certification as to Forced or Indentured... products on the List of Products Requiring Contractor Certification as to Forced or Indentured Child Labor... contracting officer must check the List of Products Requiring Contractor Certification as to Forced or...

Effects of oligotrophication on primary production in peri-alpine lakes

NASA Astrophysics Data System (ADS)

Finger, David; Wüest, Alfred; Bossard, Peter

2013-08-01

During the second half of the 20th century untreated sewage released from housing and industry into natural waters led to a degradation of many freshwater lakes and reservoirs worldwide. In order to mitigate eutrophication, wastewater treatment plants, including Fe-induced phosphorus precipitation, were implemented throughout the industrialized world, leading to reoligotrophication in many freshwater lakes. To understand and assess the effects of reoligotrophication on primary productivity, we analyzed 28 years of 14C assimilation rates, as well as other biotic and abiotic parameters, such as global radiation, nutrient concentrations and plankton densities in peri-alpine Lake Lucerne, Switzerland. Using a simple productivity-light relationship, we estimated continuous primary production and discussed the relation between productivity and observed limnological parameters. Furthermore, we assessed the uncertainty of our modeling approach based on monthly 14C assimilation measurements using Monte Carlo simulations. Results confirm that monthly sampling of productivity is sufficient for identifying long-term trends in productivity and that conservation management has successfully improved water quality during the past three decades via reducing nutrients and primary production in the lake. However, even though nutrient concentrations have remained constant in recent years, annual primary production varies significantly from year to year. Despite the fact that nutrient concentrations have decreased by more than an order of magnitude, primary production has decreased only slightly. These results suggest that primary production correlates well to nutrients availability but meteorological conditions lead to interannual variability regardless of the trophic status of the lake. Accordingly, in oligotrophic freshwaters meteorological forcing may reduce productivity impacting on the entire food chain of the ecosystem.

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

EPA Science Inventory

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...

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

USDA-ARS?s Scientific Manuscript database

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 ...

Degradation of acrylamide by the UV/chlorine advanced oxidation process.

PubMed

Gao, Ze-Chen; Lin, Yi-Li; Xu, Bin; Pan, Yang; Xia, Sheng-Ji; Gao, Nai-Yun; Zhang, Tian-Yang; Chen, Ming

2017-11-01

The degradation of acrylamide (AA) during UV/chlorine advanced oxidation process (AOP) was investigated in this study. The degradation of AA was negligible during UV irradiation alone. However, AA could be effectively degraded and mineralized during UV/chlorination due to the generation of hydroxyl radicals (OH). The degradation kinetics of AA during UV/chlorination fitted the pseudo-first order kinetics with the rate constant between AA and OH radicals being determined as 2.11 × 10 9  M -1  s -1 . The degradation rate and mineralization of AA during UV/chlorination were significantly promoted at acidic conditions as well as increasing chlorine dosage. The volatile degradation products of AA during UV/chlorination were identified using gas chromatography-mass spectrometry and the degradation pathways were then proposed accordingly. The formation of disinfection by-products (DBPs) in Milli-Q water and tap water during UV/chlorination of AA was also investigated. The DBPs included chloroform, dichloroacetonitrile, trichloroacetonitrile, 2,2-dichloroacetamide and 2,2,2-trichloroacetamide. Furthermore, the variations of AA degradation during UV/chlorination in different real water samples were evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulation and experiment on the catalytic degradation of high-concentration SF6 on TiO2 surface under UV light

NASA Astrophysics Data System (ADS)

Zhang, Ying; Li, Yalong; Cui, Zhaolun; Chen, Dachang; Zhang, Xiaoxing

2018-05-01

The high-temperature effect gas SF6 is used in the power industry, and its emissions are increasing daily. Therefore, the degradation of SF6 is particularly important. In this work, SF6 with a high concentration of 2% was degraded using the catalytic principle of TiO2 under UV light at normal temperature and pressure. Experimental results proved that this method can effectively degrade SF6. Moreover, the addition of TiO2 can effectively increase the degradation rate of SF6. The degradation of eight pieces of TiO2 with a unit area of 3 cm2 was 8.98% after 3 h of catalysis. FTIR spectral analysis showed that the main degradation products were SO2F2, SiF4, SF4, and SO2. Adding H2O can further increase the degradation rate, which can reach 27.22% in 3 h. The main degradation products were SO2F2, SiF4, SF4, SiH4, HF, and SO2. Finally, simulations verified the catalytic decomposition of SF6 on the surface of TiO2.

Identification, Characterization, and Quantification of Impurities of Safinamide Mesilate: Process-Related Impurities and Degradation Products.

PubMed

Zou, Liang; Sun, Lili; Zhang, Hui; Hui, Wenkai; Zou, Qiaogen; Zhu, Zheying

2017-07-01

The characterization of process-related impurities and degradation products of safinamide mesilate (SAFM) in bulk drug and a stability-indicating HPLC method for the separation and quantification of all the impurities were investigated. Four process-related impurities (Imp-B, Imp-C, Imp-D, and Imp-E) were found in the SAFM bulk drug. Five degradation products (Imp-A, Imp-C, Imp-D, Imp-E, and Imp-F) were observed in SAFM under oxidative conditions. Imp-C, Imp-D, and Imp-E were also degradation products and process-related impurities. Remarkably, one new compound, identified as (S)-2-[4-(3-fluoro-benzyloxy) benzamido] propanamide (i.e., Imp-D), is being reported here as an impurity for the first time. Furthermore, the structures of the aforementioned impurities were characterized and confirmed via IR, NMR, and MS techniques, and the most probable formation mechanisms of all impurities proposed according to the synthesis route. Optimum separation was achieved on an Inertsil ODS-3 column (250 × 4.6 mm, 5 μm), using 0.1% formic acid in water (pH adjusted to 5.0) and acetonitrile as the mobile phase in gradient mode. The proposed method was found to be stability-indicating, precise, linear, accurate, sensitive, and robust for the quantitation of SAFM and its process-related substances, including its degradation products.

Development and application of a validated stability-indicating high-performance liquid chromatographic method using photodiode array detection for simultaneous determination of granisetron, methylparaben, propylparaben, sodium benzoate, and their main degradation products in oral pharmaceutical preparations.

PubMed

Hewala, Ismail; El-Fatatry, Hamed; Emam, Ehab; Mabrouk, Mokhtar

2011-01-01

A simple, rapid, and sensitive RP-HPLC method using photodiode array detection was developed and validated for the simultaneous determination of granisetron hydrochloride, 1-methyl-1H-indazole-3-carboxylic acid (the main degradation product of granisetron), sodium benzoate, methylparaben, propylparaben, and 4-hydroxybenzoic acid (the main degradation product of parabens) in granisetron oral drops and solutions. The separation of the compounds was achieved within 8 min on a SymmetryShield RP18 column (100 x 4.6 mm id, 3.5 microm particle size) using the mobile phase acetonitrile--0.05 M KH2PO4 buffered to pH 3 using H3PO4 (3+7, v/v). The photodiode array detector was used to test the purity of the peaks, and the chromatograms were extracted at 240 nm. The method was validated, and validation acceptance criteria were met in all cases. The robust method was successfully applied to the determination of granisetron and preservatives, as well as their degradation products in different batches of granisetron oral drops and solutions. The method proved to be sensitive for determination down to 0.04% (w/w) of granisetron degradation product relative to granisetron and 0.03% (w/w) 4-hydroxybenzoic acid relative to total parabens.

Gas-phase and particulate products from the atmospheric degradation of the organothiophosphorus insecticide chlorpyrifos-methyl.

PubMed

Borrás, Esther; Tortajada-Genaro, Luis Antonio; Ródenas, Milagros; Vera, Teresa; Coscollá, Clara; Yusá, Vicent; Muñoz, Amalia

2015-11-01

The phosphorothioate structure is highly present in several organophosphorus pesticides. However, there is insufficient information about its degradation process after the release to the atmosphere and the secondary pollutants formed. Herein, the atmospheric reaction of chlorpyrifos-methyl (o,o-dimethyl o-(3,5,6-trichloropyridin-2-yl) phosphorothioate), is described for semi-urban or rural locations. The photo-oxidation under low NOx conditions (5-55 ppbV) was reproduced in a large outdoor simulation chamber, observing a rapid degradation (lifetime<3.5 h). The formation of gaseous products and particulate matter (aerosol yield 2-8%) was monitored. The chemical composition of minor products (gaseous and particulate) was studied, identifying 15 multi-oxygenated derivatives. The most abundant products were ring-retaining molecules such as o,o-dimethyl o-(3,5,6-trichloropyridin-2-yl) phosphorothioate, dimethyl 3,5,6-trichloropyridin-2-yl phosphate, o-methyl o-(3,5,6-trichloropyridin-2-yl) hydrogen phosphorothioate, 3,5,6-trichloropyridin-2-yl dihydrogen phosphate, 3,5,6-trichloropyridin-2-ol, and 3,5,6-trichloropyridine-2,4-diol. An atmospheric degradation mechanism has been proposed based on an oxidation started with OH-nucleophilic attack to P=S bond. The results have been extrapolated to other organothiophosphorus molecules, such as malathion, parathion, diazinon and methidathion, among many others, to estimate their photo-oxidative degradation and the expected products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Strategies to alleviate poverty and grassland degradation in Inner Mongolia: intensification vs production efficiency of livestock systems.

PubMed

Briske, David D; Zhao, Mengli; Han, Guodong; Xiu, Changbai; Kemp, David R; Willms, Walter; Havstad, Kris; Kang, Le; Wang, Zhongwu; Wu, Jianguo; Han, Xingguo; Bai, Yongfei

2015-04-01

Semi-nomadic pastoralism was replaced by sedentary pastoralism in Inner Mongolia during the 1960's in response to changes in land use policy and increasing human population. Large increases in numbers of livestock and pastoralist households (11- and 9-fold, respectively) during the past 60 yrs have variously degraded the majority of grasslands in Inner Mongolia (78 M ha) and jeopardize the livelihoods of 24 M human inhabitants. A prevailing strategy for alleviating poverty and grassland degradation emphasizes intensification of livestock production systems to maintain both pastoral livelihoods and large livestock numbers. We consider this strategy unsustainable because maximization of livestock revenue incurs high supplemental feed costs, marginalizes net household income, and promotes larger flock sizes to create a positive feedback loop driving grassland degradation. We offer an alternative strategy that increases both livestock production efficiency and net pastoral income by marketing high quality animal products to an increasing affluent Chinese economy while simultaneously reducing livestock impacts on grasslands. We further caution that this strategy be designed and assessed within a social-ecological framework capable of coordinating market expansion for livestock products, sustainable livestock carrying capacities, modified pastoral perceptions of success, and incentives for ecosystem services to interrupt the positive feedback loop that exists between subsistence pastoralism and grassland degradation in Inner Mongolia. Copyright © 2015. Published by Elsevier Ltd.

Identification of a new degradation product of the antifouling agent Irgarol 1051 in natural samples

USGS Publications Warehouse

Ferrer, I.; Barcelo, D.

2001-01-01

A main degradation product of Irgarol [2-(methylthio)-4-(tert-butylamino)-6-(cyclopropylamino)-s-triazine], one of the most widely used compounds in antifouling paints, was detected at trace levels in seawater and sediment samples collected from several marinas on the Mediterranean coast. This degradation product was identified as 2-methylthio-4-tert-butylamino-s-triazine. The unequivocal identification of this compound in seawater samples was carried out by solid-phase extraction (SPE) coupled on-line with liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS). SPE was carried out by passing 150 ml of seawater sample through a cartridge containing a polymeric phase (PLRP-s), with recoveries ranging from 92 to 108% (n=5). Using LC-MS detection in positive ion mode, useful structural information was obtained by increasing the fragmentor voltage, thus permitting the unequivocal identification of this compound in natural samples. Method detection limits were in the range of 0.002 to 0.005 ??g/l. Overall, the combination of on-line SPE and LC-APCI-MS represents an important advance in environmental analysis of herbicide degradation products in seawater, since it demonstrates that trace amounts of new polar metabolites may be determined rapidly. This paper reports the LC-MS identification of the main degradation product of Irgarol in seawater and sediment samples. ?? 2001 Elsevier Science B.V. All rights reserved.

Designation of less favorable areas by the regionalization of soil degradation on various spatial scales

NASA Astrophysics Data System (ADS)

Pásztor, L.; Szabó, J.; Bakacsi, Zs.; Laborczi, A.

2009-04-01

One of the main objectives of the EU's Common Agricultural Policy is to encourage maintaining agricultural production in less favorable areas (LFA) in order (among others) to sustain agricultural production and use natural resources, in such a way to secure both stable production and income to farmers and to protect the environment. LFA assignment has both ecological and severe economical aspects. Delimitation of LFAs can be carried out by using biophysical diagnostic criteria on low soil productivity and poor climate conditions. Identification of low-productivity areas requires regionalization of soil functions related to food and other biomass production. This process can be carried out in different scales from national to local level, but always requires map-based pedological and further environmental information with appropriate spatial resolution. For the regionalization of less productive areas in national scale a functional approach was used which integrates the knowledge on soil degradation processes in nationwide level. Specific soil threats were classified into ranked categories. Supposing (quasi)uniform distribution of vulnerability measure along these classes, we introduced a "standardized" value as a ratio of the class order to the maximum class order expressed in percentage. For the overall spatial characterization of degradation status, spatial information was integrated in a result map by summarizing the degradation specific "standardized" cell values. This map in one hand has been used for the delineation of soil degradation regions. On the other hand appropriate spatial aggregation of index values on geographical and administrative regions is suitable for their quantitative comparison thus they can be ranked and this feature can be used for the identification of less favorable areas. At the more detailed, county level the Digital Kreybig Soil Information System was used as a tool of the regionalization of soil functions related to soil productivity. Concurrent spatial analysis of the suitability of soils for agricultural use and their sensitivity to physical and chemical degradation were carried out which resulted in a so-called ecotype-based characterization of land. As a spin-off, this classification was used for the designation of low productive areas suitable for hypogenous and cap fungi plantations as landuse alternative for croplands.

Highly sensitive single-fibril erosion assay demonstrates mechanochemical switch in native collagen fibrils

PubMed Central

Flynn, Brendan P.; Tilburey, Graham E.

2013-01-01

It has been established that the enzyme susceptibility of collagen, the predominant load-bearing protein in vertebrates, is altered by applied tension. However, whether tensile force increases or decreases the susceptibility to enzyme is a matter of contention. It is critical to establish a definitive understanding of the direction and magnitude of the force versus catalysis rate (kC) relationship if we are to properly interpret connective tissue development, growth, remodeling, repair, and degeneration. In this investigation, we examine collagen/enzyme mechanochemistry at the smallest scale structurally relevant to connective tissue: the native collagen fibril. A single-fibril mechanochemical erosion assay with nN force resolution was developed which permits detection of the loss of a few layers of monomer from the fibril surface. Native type I fibrils (bovine) held at three levels of tension were exposed to Clostridium histolyticum collagenase A. Fibrils held at zero-load failed rapidly and consistently (20 min) while fibrils at 1.8 pN/monomer failed more slowly (35–55 min). Strikingly, fibrils at 23.9 pN/monomer did not exhibit detectable degradation. The extracted force versus kC data were combined with previous single-molecule results to produce a “master curve” which suggests that collagen degradation is governed by an extremely sensitive mechanochemical switch. PMID:22584606

The notion of climate-driven strath-terrace production assessed via dissimilar stream-process response to late Quaternary climate

USGS Publications Warehouse

García, Antonio F.; Mahan, Shannon

2014-01-01

Previous research results from the Gabilan Mesa are combined with new optically stimulated luminescence (OSL) age estimates and sedimentological analyses with the aim of identifying factors that inhibit climate-driven strath-terrace production, and factors that make possible strath-terrace production independent of climate forcing. The factors are revealed by comparing the morphostratigraphy and OSL age estimates of terraces in the adjacent San Lorenzo Creek and Pancho Rico Creek drainage basins of the central California Coast Ranges. OSL age estimates on San Lorenzo Creek fill-terrace alluvium overlying bedrock at two paleofluvial levels range between 50.5 and 41.3 ka and between 33.4 and 18.2 ka. These OSL age estimates indicate that although the channel of Pancho Rico Creek was degrading at these times, San Lorenzo Creek aggradation was synchronous with previously documented regional, climatically driven aggradation that elsewhere in southern California led to strath production and alluvial deposition. The regional-scale climate forcing events had different effects on San Lorenzo and Pancho Rico Creeks because of the influences of drainage-basin lithology on bedload size and tectonic tilting direction on base-level fall. The Holocene history of channel denudation and strath production of Pancho Rico Creek is also different from that of San Lorenzo Creek, and different from that of many other streams in southern California. After Pancho Rico Creek captured the upper part of the drainage basin of San Lorenzo Creek sometime after 15.5 to 11.7 ka, Pancho Rico Creek has been producing unpaired, erosional strath terraces. The weak, clay rich, fine-grained sedimentary rock underlying Pancho Rico Valley is an ideal substrate in which to form straths. The meandering channel of Pancho Rico Creek produces straths, and weathering resistant, relatively hard bedload introduced by stream capture ensures their preservation as strath terraces.

Vitamin E: Curse or Benefit in Alzheimer's Disease? A Systematic Investigation of the Impact of α-, γ- and δ-Tocopherol on Aß Generation and Degradation in Neuroblastoma Cells.

PubMed

Grimm, M O W; Stahlmann, C P; Mett, J; Haupenthal, V J; Zimmer, V C; Lehmann, J; Hundsdörfer, B; Endres, K; Grimm, H S; Hartmann, T

2015-06-01

The E vitamins are a class of lipophilic compounds including tocopherols, which have high antioxidative properties. Because of the elevated lipid peroxidation and increased reactive oxidative species in Alzheimer's disease (AD) many attempts have been made to slow down the progression of AD by utilizing the antioxidative action of vitamin E. Beside the mixed results of these studies nothing is known about the impact of vitamin E on the mechanisms leading to amyloid-β production and degradation being responsible for the plaque formation, one of the characteristic pathological hallmarks in AD. Here we systematically investigate the influence of different tocopherols on Aβ production and degradation in neuronal cell lines. Beside amyloid-β level the mechanisms leading to Aβ production and degradation are examined. Surprisingly, all tocopherols have shown to increase Aβ level by enhancing the Aβ production and decreasing the Aβ degradation. Aβ production is enhanced by an elevated activity of the involved enzymes, the β- and γ-secretase. These secretases are not directly affected, but tocopherols increase their protein level and expression. We could identify significant differences between the single tocopherols; whereas α-tocopherol had only minor effects on Aβ production, δ-tocopherol showed the highest potency to increase Aβ generation. Beside Aβ production, Aβ clearance was decreased by affecting IDE, one of the major Aβ degrading enzymes. Our results suggest that beside the beneficial antioxidative effects of vitamin E, tocopherol has in respect to AD also a potency to increase the amyloid-β level, which differ for the analysed tocopherols. We therefore recommend that further studies are needed to clarify the potential role of these various vitamin E species in respect to AD and to identify the form which comprises an antioxidative property without having an amyloidogenic potential.

Antifoam degradation testing

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

Lambert, D. P.; Zamecnik, J. R.; Newell, D. D.

2015-08-20

This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

Receptor for advanced glycation end products is targeted by FBXO10 for ubiquitination and degradation.

PubMed

Evankovich, John; Lear, Travis; Mckelvey, Alison; Dunn, Sarah; Londino, James; Liu, Yuan; Chen, Bill B; Mallampalli, Rama K

2017-09-01

The receptor for advanced glycation end products (RAGE) is a highly expressed cell membrane receptor serving to anchor lung epithelia to matrix components, and it also amplifies inflammatory signaling during acute lung injury. However, mechanisms that regulate its protein concentrations in cells remain largely unknown. Here we show that RAGE exhibits an extended life span in lung epithelia ( t ½ 6 h), is monoubiquitinated at K374, and is degraded in lysosomes. The RAGE ligand ODN2006, a synthetic oligodeoxynucleotide resembling pathogenic hypomethylated CpG DNA, promotes rapid lysosomal RAGE degradation through activation of protein kinase Cζ (PKCζ), which phosphorylates RAGE. PKCζ overexpression enhances RAGE degradation, while PKCζ knockdown stabilizes RAGE protein levels and prevents ODN2006-mediated degradation. We identify that RAGE is targeted by the ubiquitin E3 ligase subunit F-box protein O10 (FBXO10), which associates with RAGE to mediate its ubiquitination and degradation. FBXO10 depletion in cells stabilizes RAGE and is required for ODN2006-mediated degradation. These data suggest that modulation of regulators involved in ubiquitin-mediated disposal of RAGE might serve as unique molecular inputs directing RAGE cellular concentrations and downstream responses, which are critical in an array of inflammatory disorders, including acute lung injury.-Evankovich, J., Lear, T., Mckelvey, A., Dunn, S., Londino, J., Liu, Y., Chen, B. B., Mallampalli, R. K. Receptor for advanced glycation end products is targeted by FBXO10 for ubiquitination and degradation. © FASEB.

DFN-M field characterization of sandstone for a process-based site conceptual model and numerical simulations of TCE transport with degradation

NASA Astrophysics Data System (ADS)

Pierce, Amanda A.; Chapman, Steven W.; Zimmerman, Laura K.; Hurley, Jennifer C.; Aravena, Ramon; Cherry, John A.; Parker, Beth L.

2018-05-01

Plumes of trichloroethene (TCE) with degradation products occur at a large industrial site in California where TCE as a dense non-aqueous phase liquid (DNAPL) entered the fractured sandstone bedrock at many locations beginning in the late 1940s. Groundwater flows rapidly in closely spaced fractures but plume fronts are strongly retarded relative to groundwater flow velocities owing largely to matrix diffusion in early decades and degradation processes in later decades and going forward. Multiple data types show field evidence for both biotic and abiotic dechlorination of TCE and its degradation products, resulting in non-chlorinated compounds. Analyses were conducted on groundwater samples from hundreds of monitoring wells and on thousands of rock samples from continuous core over depths ranging from 6 to 426 metres below ground surface. Nearly all of the present-day mass of TCE and degradation products resides in the water-saturated, low-permeability rock matrix blocks. Although groundwater and DNAPL flow primarily occur in the fractures, DNAPL dissolution followed by diffusion and sorption readily transfers contaminant mass into the rock matrix. The presence of non-chlorinated degradation products (ethene, ethane, acetylene) and compound specific isotope analysis (CSIA) of TCE and cis-1,2-dichloroethene (cDCE) indicate at least some complete dechlorination by both biotic and abiotic pathways, consistent with the observed mineralogy and hydrogeochemistry and with published results from crushed rock microcosms. The rock matrix contains abundant iron-bearing minerals and solid-phase organic carbon with large surface areas and long contact times, suggesting degradation processes are occurring in the rock matrix. Multiple, high-resolution datasets provide strong evidence for spatially heterogeneous distributions of TCE and degradation products with varying degrees of degradation observed only when using new methods that achieve better detection of dissolved gases (i.e., Snap Sampler™) and contaminant mass stored in the low permeability rock matrix (i.e., CORE-DFN™). Simulations using a discrete fracture-matrix (DFN-M) numerical model capable of rigorously simulating flow and transport in both the fractures and matrix, including interactions, show that even slow, first-order degradation rates (i.e., 5- to 20-year half-lives) informed by site-derived parameters can contribute strongly to natural attenuation, resulting in TCE plumes that become stationary in space and might even retreat after 50 to 100 years, if the DNAPL sources become depleted due to the combination of diffusion and degradation processes.

DFN-M field characterization of sandstone for a process-based site conceptual model and numerical simulations of TCE transport with degradation.

PubMed

Pierce, Amanda A; Chapman, Steven W; Zimmerman, Laura K; Hurley, Jennifer C; Aravena, Ramon; Cherry, John A; Parker, Beth L

2018-05-01

Plumes of trichloroethene (TCE) with degradation products occur at a large industrial site in California where TCE as a dense non-aqueous phase liquid (DNAPL) entered the fractured sandstone bedrock at many locations beginning in the late 1940s. Groundwater flows rapidly in closely spaced fractures but plume fronts are strongly retarded relative to groundwater flow velocities owing largely to matrix diffusion in early decades and degradation processes in later decades and going forward. Multiple data types show field evidence for both biotic and abiotic dechlorination of TCE and its degradation products, resulting in non-chlorinated compounds. Analyses were conducted on groundwater samples from hundreds of monitoring wells and on thousands of rock samples from continuous core over depths ranging from 6 to 426 metres below ground surface. Nearly all of the present-day mass of TCE and degradation products resides in the water-saturated, low-permeability rock matrix blocks. Although groundwater and DNAPL flow primarily occur in the fractures, DNAPL dissolution followed by diffusion and sorption readily transfers contaminant mass into the rock matrix. The presence of non-chlorinated degradation products (ethene, ethane, acetylene) and compound specific isotope analysis (CSIA) of TCE and cis-1,2-dichloroethene (cDCE) indicate at least some complete dechlorination by both biotic and abiotic pathways, consistent with the observed mineralogy and hydrogeochemistry and with published results from crushed rock microcosms. The rock matrix contains abundant iron-bearing minerals and solid-phase organic carbon with large surface areas and long contact times, suggesting degradation processes are occurring in the rock matrix. Multiple, high-resolution datasets provide strong evidence for spatially heterogeneous distributions of TCE and degradation products with varying degrees of degradation observed only when using new methods that achieve better detection of dissolved gases (i.e., Snap Sampler™) and contaminant mass stored in the low permeability rock matrix (i.e., CORE-DFN™). Simulations using a discrete fracture-matrix (DFN-M) numerical model capable of rigorously simulating flow and transport in both the fractures and matrix, including interactions, show that even slow, first-order degradation rates (i.e., 5- to 20-year half-lives) informed by site-derived parameters can contribute strongly to natural attenuation, resulting in TCE plumes that become stationary in space and might even retreat after 50 to 100 years, if the DNAPL sources become depleted due to the combination of diffusion and degradation processes. Copyright © 2018 Elsevier B.V. All rights reserved.

Influence of dihydroxybenzenes on paracetamol and ciprofloxacin degradation and iron(III) reduction in Fenton processes.

PubMed

Costa E Silva, Beatriz; de Lima Perini, João Angelo; Nogueira, Raquel F Pupo

2017-03-01

The degradation of paracetamol (PCT) and ciprofloxacin (CIP) was compared in relation to the generation of dihydroxylated products, Fe(III) reduction and reaction rate in the presence of dihydroxybenzene (DHB) compounds, or under irradiation with free iron (Fe 3+ ) or citrate complex (Fecit) in Fenton or photo-Fenton process. The formation of hydroquinone (HQ) was observed only during PCT degradation in the dark, which increased drastically the rate of PCT degradation, since HQ formed was able to reduce Fe 3+ and contributed to PCT degradation efficiency. When HQ was initially added, PCT and CIP degradation rate in the dark was much higher in comparison to the absence of HQ, due to the higher and faster formation of Fe 2+ at the beginning of reaction. In the absence of HQ, no CIP degradation was observed; however, when HQ was added after 30 min, the degradation rate increased drastically. Ten PCT hydroxylated intermediates were identified in the absence of HQ, which could contribute for Fe(III) reduction and consequently to the degradation in a similar way as HQ. During CIP degradation, only one product of hydroxyl radical attack on benzene ring and substitution of the fluorine atom was identified when HQ was added to the reaction medium.

Degradation of chondroitin sulfate by the gut microbiota of Chinese individuals.

PubMed

Shang, Qingsen; Yin, Yeshi; Zhu, Liying; Li, Guoyun; Yu, Guangli; Wang, Xin

2016-05-01

Oral preparations of chondroitin sulfate (CS) have long been used as anti-osteoarthritis (anti-OA) drugs. However, little is known about the degradation of CS by human gut microbiota. In the present study, degradation profiles of CSA (the main constituent of CS drugs) by the human gut microbiota from six healthy subjects were investigated. Each individual's microbiota had differing degradation activities, but ΔUA-GalNAc4S was the end product in all cases. To elucidate the mechanisms underlying this phenomenon, different CSA-degrading bacteria were isolated from each individual's microbiota and tested for CSA degradation. In addition to Bacteroides thetaiotaomicron J1, Bacteroides thetaiotaomicron 82 and Bacteroides ovatus E3, a new CSA-degrading bacterium, Clostridium hathewayi R4, was isolated and characterized. Interestingly, at least two different CSA-degrading species were identified from each individual's gut microbiota. Predictably, these functional bacteria also had differing degradation rates, but still generated the same end product, ΔUA-GalNAc4S. In addition, the human fecal isolates produced different degradation profiles for CSC, CSD, and CSE, suggesting that CS could be readily metabolized to varying extents by diverse microbial consortiums, which may help to explain the poor bioavailability and unequal efficacy of CS among individuals in OA treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

A metabolic basis for impaired muscle force production and neuromuscular compensation during sprint cycling.

PubMed

Bundle, Matthew W; Ernst, Carrie L; Bellizzi, Matthew J; Wright, Seth; Weyand, Peter G

2006-11-01

For both different individuals and modes of locomotion, the external forces determining all-out sprinting performances fall predictably with effort duration from the burst maximums attained for 3 s to those that can be supported aerobically as trial durations extend to roughly 300 s. The common time course of this relationship suggests a metabolic basis for the decrements in the force applied to the environment. However, the mechanical and neuromuscular responses to impaired force production (i.e., muscle fatigue) are generally considered in relation to fractions of the maximum force available, or the maximum voluntary contraction (MVC). We hypothesized that these duration-dependent decrements in external force application result from a reliance on anaerobic metabolism for force production rather than the absolute force produced. We tested this idea by examining neuromuscular activity during two modes of sprint cycling with similar external force requirements but differing aerobic and anaerobic contributions to force production: one- and two-legged cycling. In agreement with previous studies, we found greater peak per leg aerobic metabolic rates [59% (+/-6 SD)] and pedal forces at VO2 peak [30% (+/-9)] during one- vs. two-legged cycling. We also determined downstroke pedal forces and neuromuscular activity by surface electromyography during 15 to 19 all-out constant load sprints lasting from 12 to 400 s for both modes of cycling. In support of our hypothesis, we found that the greater reliance on anaerobic metabolism for force production induced compensatory muscle recruitment at lower pedal forces during two- vs. one-legged sprint cycling. We conclude that impaired muscle force production and compensatory neuromuscular activity during sprinting are triggered by a reliance on anaerobic metabolism for force production.

Factors to consider in developing individual pharmaceutical product quality risk profiles useful to government procurement agencies

PubMed Central

Xu, Wei; Boehm, Garth; Zheng, Qiang

2015-01-01

Governments that procure pharmaceutical products from an Essential Medicine List (EML) bear special responsibility for the quality of these products. In this article we examine the possibility of developing a pharmaceutical product quality risk assessment scheme for use by government procurement officials. We use the Chinese EML as a basis, and US recall data is examined as it is publically available.This is justified as the article is only concerned with inherent product quality risks. After establishing a link between Chinese essential medicines and those available in the US, we examine US recall data to separate product specific recalls. We conclude that, in addition to existing manufacturing based risks, there are two other product specific risks that stand out from all others, degradation and dissolution failure. Methodology for relative product risk for degradation is needed to be developed and further work is required to better understand dissolution failures which largely occur with modified-release solid oral products. We conclude that a product specific quality risk profile would be enhanced by including a risk assessment for degradation for all products, and in the case of solid oral products, dissolution. PMID:26904402

Factors to consider in developing individual pharmaceutical product quality risk profiles useful to government procurement agencies.

PubMed

Xu, Wei; Boehm, Garth; Zheng, Qiang

2016-01-01

Governments that procure pharmaceutical products from an Essential Medicine List (EML) bear special responsibility for the quality of these products. In this article we examine the possibility of developing a pharmaceutical product quality risk assessment scheme for use by government procurement officials. We use the Chinese EML as a basis, and US recall data is examined as it is publically available.This is justified as the article is only concerned with inherent product quality risks. After establishing a link between Chinese essential medicines and those available in the US, we examine US recall data to separate product specific recalls. We conclude that, in addition to existing manufacturing based risks, there are two other product specific risks that stand out from all others, degradation and dissolution failure. Methodology for relative product risk for degradation is needed to be developed and further work is required to better understand dissolution failures which largely occur with modified-release solid oral products. We conclude that a product specific quality risk profile would be enhanced by including a risk assessment for degradation for all products, and in the case of solid oral products, dissolution.

MEASUREMENT AND MODELING OF THE TRANSPORT OF ENDOCRINE DISRUPTING DICARBOXIMIDES AND DEGRADATION PRODUCTS FROM THE SOIL TO THE LOWER TROPOSPHERE

EPA Science Inventory

This research addresses the environmental fate, transport, exposure and potential risks from dicarboximides, a widely used class of agricultural fungicides. Certain dicarboximide fungicides and degradation products have been found to be anti-androgenic; i. e., exposure to these...

MEASURING AND MODELING THE TRANSPORT OF ENDOCRINE DISRUPTING DICARBOXIMIDES AND DEGRADATION PRODUCTS FROM THE SOIL TO THE LOWER TROPOSPHERE

EPA Science Inventory

This research addresses the environmental fate, transport, exposure and potential risks from dicarboximides, a widely used class of agricultural fungicides. Certain dicarboximide fungicides and degradation products have been found to be anti-androgenic; i. e., exposure to these...

Activity of meadowfoam (Limnanthes alba) seed meal glucolimnanthin degradation products against soilborne pathogens

USDA-ARS?s Scientific Manuscript database

Meadowfoam (Limnanthes alba L.) is a herbaceous winter-spring annual grown as a commercial oilseed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products, and therefore the mea...

ANALYSIS OF THE FLUX OF AN ENDOCRINE DISRUPTING DICARBOXIMIDE AND ITS DEGRADATION PRODUCTS FROM THE SOIL TO THE LOWER TROPOSPHERE

EPA Science Inventory

A method for measuring the atmospheric flux of the antiandrogenic dicarboxirnide, vinclozolin, and its degradation products was investigated. A nitric oxide laboratory chamber was modified to measure the flux of semi-volatile compounds. Pesticide application systems and soil in...

MEASURING THE TRANSPORT OF ENDOCRINE DISRUPTING DICARBOXIMIDES AND DEGRADATION PRODUCTS FROM THE SOIL TO THE LOWER TROPOSPHERE

EPA Science Inventory

A method for measuring the atmospheric flux of a dicarboximide and its degradation products was investigated. A volatile gas laboratory chamber was modified to measure the flux of semi-volatile fungicides. Pesticide application systems and soil incorporation systems were desig...

Detecting and monitoring deforestation and forest degradation: Issues and obstacles for Southeast Asia

Treesearch

Douglas Muchoney; Sharon Hamann

2013-01-01

Forest degradation can be defined as the loss of forest volume, biomass and/or forest productivity caused by natural or human influences. Achieving Reduced Emissions from Deforestation and Forest Degradation (REDD+) requires that deforestation and degradation can be efficiently, reliably, and cost-effectively detected and quantified, often where ground and aerial...

Ethanol production by Saccharomyces cerevisiae using lignocellulosic hydrolysate from Chrysanthemum waste degradation.

PubMed

Quevedo-Hidalgo, Balkys; Monsalve-Marín, Felipe; Narváez-Rincón, Paulo César; Pedroza-Rodríguez, Aura Marina; Velásquez-Lozano, Mario Enrique

2013-03-01

Ethanol production derived from Saccharomyces cerevisiae fermentation of a hydrolysate from floriculture waste degradation was studied. The hydrolysate was produced from Chrysanthemum (Dendranthema grandiflora) waste degradation by Pleurotus ostreatus and characterized to determine the presence of compounds that may inhibit fermentation. The products of hydrolysis confirmed by HPLC were cellobiose, glucose, xylose and mannose. The hydrolysate was fermented by S. cerevisiae, and concentrations of biomass, ethanol, and glucose were determined as a function of time. Results were compared to YGC modified medium (yeast extract, glucose and chloramphenicol) fermentation. Ethanol yield was 0.45 g g(-1), 88 % of the maximal theoretical value. Crysanthemum waste hydrolysate was suitable for ethanol production, containing glucose and mannose with adequate nutrients for S. cerevisiae fermentation and low fermentation inhibitor levels.

Reactions of clofibric acid with oxidative and reductive radicals-Products, mechanisms, efficiency and toxic effects

NASA Astrophysics Data System (ADS)

Csay, Tamás; Rácz, Gergely; Salik, Ádám; Takács, Erzsébet; Wojnárovits, László

2014-09-01

The degradation of clofibric acid induced by hydroxyl radical, hydrated electron and O2-•/HO2• reactive species was studied in aqueous solutions. Clofibric acid was decomposed more effectively by hydroxyl radical than by hydrated electron or O2-•/HO2•. Various hydroxylated, dechlorinated and fragmentation products have been identified and quantified. A new LC-MS method was developed based on 18O isotope labeling to follow the formation of hydroxylated derivatives of clofibric acid. Possible degradation pathways have been proposed. The overall degradation was monitored by determination of sum parameters like COD, TOC and AOX. It was found that the organic chlorine degrades very effectively prior to complete mineralization. After the treatment no toxic effect was found according to Vibrio fischeri tests. However, at early stages some of the reaction products were more harmful than clofibric acid.

The individual and cumulative effect of brominated flame retardant and polyvinylchloride (PVC) on thermal degradation of acrylonitrile-butadiene-styrene (ABS) copolymer.

PubMed

Brebu, Mihai; Bhaskar, Thallada; Murai, Kazuya; Muto, Akinori; Sakata, Yusaku; Uddin, Md Azhar

2004-08-01

Acrylonitrile-butadiene-styrene (ABS) copolymers without and with a polybrominated epoxy type flame retardant were thermally degraded at 450 degrees C alone (10 g) and mixed with polyvinylchloride (PVC) (8 g/2 g). Gaseous and liquid products of degradation were analysed by various gas chromatographic methods (GC with TCD, FID, AED, MSD) in order to determine the individual and cumulative effect of bromine and chlorine on the quality and quantity of degradation compounds. It was found that nitrogen, chlorine, bromine and oxygen are present as organic compounds in liquid products, their quantity depends on the pyrolysed polymer or polymer mixture. Bromophenol and dibromophenols were the main brominated compounds that come from the flame retardant. 1-Chloroethylbenzene was the main chlorine compound observed in liquid products. It was also determined that interactions appear at high temperatures during decomposition between the flame retardant, PVC and the ABS copolymer.

Long-term evaluation of the fate of sulfur mustard on dry and humid soils, asphalt, and concrete.

PubMed

Mizrahi, Dana M; Goldvaser, Michael; Columbus, Ishay

2011-04-15

The long-term fate of the blister agent sulfur mustard (HD, bis(2-chloroethyl)sulfide) was determined in a variety of commercial and natural matrices. HD was found to be extremely stable in dry matrices for over a year. The addition of 5% water to the matrices induced slow degradation of HD, which lasted several months. The major degradation product in sands and asphalt was found to be a sulfonium salt, S[CH(2)CH(2)S(+)(CH(2)CH(2)OH)(2)](2) (H-2TG). Red loam soil, which has not been examined before, exhibited strong interaction with HD, both in dry form and in the presence of water. Humid red loam soil gave rise to unique oxidative degradation products. On humid concrete HD degraded to a complex mixture of products, including vinyls. This may be attributed to the basic sites incorporated in concrete.

Human-Induced Vegetation Degradation in a Semi-Arid Rangeland

NASA Astrophysics Data System (ADS)

Jackson, Hasan

Current assessments of anthropogenic land degradation and its impact on vegetation at regional scales are prone to large uncertainties due to the lack of an objective, transferable, spatially and temporally explicit measure of land degradation. These uncertainties have resulted in contradictory estimates of degradation extent and severity and the role of human activities. The uncertainties limit the ability to assess the effects on the biophysical environment and effectiveness of past, current, and future policies of land use. The overall objective of the dissertation is to assess degradation in a semi-arid region at a regional scale where the process of anthropogenic land degradation is evident. Net primary productivity (NPP) is used as the primary indicator to measure degradation. It is hypothesized that land degradation resulting from human factors on the landscape irreversibly reduces NPP below the potential set by environmental conditions. It is also hypothesized that resulting reductions in NPP are distinguishable from natural, spatial and temporal, variability in NPP. The specific goals of the dissertation are to (1) identify the extent and severity of degradation using productivity as the primary surrogate, (2) compare the degradation of productivity to other known mechanisms of degradation, and (3) relate the expression of degradation to components of vegetation and varying environmental conditions. This dissertation employed the Local NPP Scaling (LNS) approach to identify patterns of anthropogenic degradation of NPP in the Burdekin Dry Tropics (BDT) region of Queensland (14 million hectares), Australia from 2000 to 2013. The method started with land classification based on the environmental factors presumed to control NPP to group pixels having similar potential NPP. Then, satellite remotely sensing data were used to compare actual NPP with its potential. The difference, in units of mass of carbon fixed in NPP per unit area per monitoring interval and per year, also its percentage of the potential, were the measures of degradation. Degradation was then compared to non-green components of vegetation (e.g. wood, stems, leaf litter, dead biomass) to determine their relationship in space and time. Finally, the symptoms of degradation were compared to land management patterns and the environmental variability (e.g. drought, non-drought conditions). Nearly 20% of the region was identified as degraded and another 7% had significant negative trends. The average annual reduction in NPP due to anthropogenic degradation was -17% of the non-degraded potential, although the severity of degradation varied substantially throughout the region. Non-green vegetation cover was strongly correlated with the inter-annual and intra-annual temporal trends of degradation. The dynamics of degradation in drought and non-drought years provided evidence of multiple stables states of degradation.

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

PubMed Central

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 (r2>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. PMID:25657790

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.

PubMed

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.

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

PubMed

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

Determination of early warning signs for photocatalytic degradation of titanium white oil paints by means of surface analysis.

PubMed

van Driel, B A; Wezendonk, T A; van den Berg, K J; Kooyman, P J; Gascon, J; Dik, J

2017-02-05

Titanium white (TiO 2 ) has been widely used as a pigment in the 20th century. However, its most photocatalytic form (anatase) can cause severe degradation of the oil paint in which it is contained. UV light initiates TiO 2 -photocatalyzed processes in the paint film, degrading the oil binder into volatile components resulting in chalking of the paint. This will eventually lead to severe changes in the appearance of a painting. To date, limited examples of degraded works of art containing titanium white are known due to the relatively short existence of the paintings in question and the slow progress of the degradation process. However, UV light will inevitably cause degradation of paint in works of art containing photocatalytic titanium white. In this work, a method to detect early warning signs of photocatalytic degradation of unvarnished oil paint is proposed, using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Consequently, a four-stage degradation model was developed through in-depth study of TiO 2 -containing paint films in various stages of degradation. The XPS surface analysis proved very valuable for detecting early warning signs of paint degradation, whereas the AFM results provide additional confirmation and are in good agreement with bulk gloss reduction. Copyright © 2016 Elsevier B.V. All rights reserved.

ST2 suppresses IL-6 production via the inhibition of I{kappa}B degradation induced by the LPS signal in THP-1 cells

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

Takezako, Naoki; Hayakawa, Morisada; Hayakawa, Hiroko

2006-03-10

LPS induces the production of inflammatory cytokines via the stimulation of Toll-like receptors. In this study, we demonstrated that a soluble secreted form of the ST2 gene product (ST2), a member of the interleukin-1 receptor family, suppressed the production of IL-6 in an LPS-stimulated human monocytic leukemia cell line, THP-1. Immunofluorescence confocal microscopy revealed the binding of ST2 to the surface of the THP-1 cells, in which ST2 led to decreased binding of nuclear factor-{kappa}B to the IL-6 promoter. Furthermore, the degradation of I{kappa}B in the cytoplasm after LPS stimulation was reduced by pretreatment with ST2. These results demonstrated thatmore » ST2 negatively regulates LPS-induced IL-6 production via the inhibition of I{kappa}B degradation in THP-1 cells.« less

Effect of calcinations temperature of CuO nanoparticle on the kinetics of decontamination and decontamination products of sulphur mustard.

PubMed

Mahato, T H; Singh, Beer; Srivastava, A K; Prasad, G K; Srivastava, A R; Ganesan, K; Vijayaraghavan, R

2011-09-15

Present study investigates the potential of CuO nanoparticles calcined at different temperature for the decontamination of persistent chemical warfare agent sulphur mustard (HD) at room temperature (30 ± 2 °C). Nanoparticles were synthesized by precipitation method and characterized by using SEM, EDAX, XRD, and Raman Spectroscopy. Synthesized nanoparticles were tested as destructive adsorbents for the degradation of HD. Reactions were monitored by GC-FID technique and the reaction products characterized by GC-MS. It was observed that the rate of degradation of HD decreases with the increase in calcination temperature and there is a change in the percentage of product of HD degradation. GC-MS data indicated that the elimination product increases with increase in calcination temperature whereas the hydrolysis product decreases. Copyright © 2011 Elsevier B.V. All rights reserved.

Reliability analysis of degradable networks with modified BPR

NASA Astrophysics Data System (ADS)

Wang, Yu-Qing; Zhou, Chao-Fan; Jia, Bin; Zhu, Hua-Bing

2017-12-01

In this paper, the effect of the speed limit on degradable networks with capacity restrictions and the forced flow is investigated. The link performance function considering the road capacity is proposed. Additionally, the probability density distribution and the cumulative distribution of link travel time are introduced in the degradable network. By the mean of distinguishing the value of the speed limit, four cases are discussed, respectively. Means and variances of link travel time and route one of the degradable road network are calculated. Besides, by the mean of performing numerical simulation experiments in a specific network, it is found that the speed limit strategy can reduce the travel time budget and mean travel time of link and route. Moreover, it reveals that the speed limit strategy can cut down variances of the travel time of networks to some extent.

Field-induced strain degradation of AlGaN/GaN high electron mobility transistors on a nanometer scale

NASA Astrophysics Data System (ADS)

Lin, Chung-Han; Doutt, D. R.; Mishra, U. K.; Merz, T. A.; Brillson, L. J.

2010-11-01

Nanoscale Kelvin probe force microscopy and depth-resolved cathodoluminescence spectroscopy reveal an electronic defect evolution inside operating AlGaN/GaN high electron mobility transistors with degradation under electric-field-induced stress. Off-state electrical stress results in micron-scale areas within the extrinsic drain expanding and decreasing in electric potential, midgap defects increasing by orders-of-magnitude at the AlGaN layer, and local Fermi levels lowering as gate-drain voltages increase above a characteristic stress threshold. The pronounced onset of defect formation, Fermi level movement, and transistor degradation at the threshold gate-drain voltage of J. A. del Alamo and J. Joh [Microelectron. Reliab. 49, 1200 (2009)] is consistent with crystal deformation and supports the inverse piezoelectric model of high electron mobility transistor degradation.

[Lactic acid bacteria proteinase and quality of fermented dairy products--A review].

PubMed

Zhang, Shuang; Zhang, Lanwei; Han, Xue

2015-12-04

Lactic acid bacteria (LAB) could synthesize cell envelope proteinase with weak activity, which primarily degrades casein. In addition to its crucial role in the rapid growth of LAB in milk, LAB proteinases are also of industrial importance due to their contribution to the formation of texture and flavor of many fermented dairy products. The proteolytic system, properties of proteinase, the degradation product of casein and its effect on the quality of fermented dairy products were reviewed in this manuscript.

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

PubMed

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.

Accelerated azo dye degradation and concurrent hydrogen production in the single-chamber photocatalytic microbial electrolysis cell.

PubMed

Hou, Yanping; Zhang, Renduo; Yu, Zebin; Huang, Lirong; Liu, Yuxin; Zhou, Zili

2017-01-01

The single-chamber microbial electrolysis cell constructed with a TiO 2 -coated photocathode, termed photocatalytic microbial electrolysis cell (PMEC), was developed to accelerate methyl orange (MO) degradation and concurrent hydrogen (H 2 ) recovery under UV irradiation. Results showed that faster MO decolorization rates were achieved from the PMEC compared with those without UV irradiation or with open circuit. With increase of MO concentrations (acetate as co-substrate) from 50 to 300mg/L at an applied voltage of 0.8V, decolorization efficiencies decreased from 98% to 76% within 12h, and cyclic H 2 production declined from 113 to 68mL. As the possible mechanism of MO degradation, bioelectrochemical reduction, co-metabolism reduction, and photocatalysis were involved; and degradation intermediates (mainly sulfanilic acid and N,N-dimethylaniline) were further degraded by OH generated from photocatalysis. This makes MO mineralization be possible in the single-chamber PMEC. Hence, the PMEC is a promising system for dyeing wastewater treatment and simultaneous H 2 production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bioprocessing of wheat and paddy straw for their nutritional up-gradation.

PubMed

Sharma, Rakesh Kumar; Arora, Daljit Singh

2014-07-01

Solid-state bioprocessing of agricultural residues seems to be an emerging and effective method for the production of high quality animal feed. Seven strains of white-rot fungi were selected to degrade wheat and paddy straw (PS) under solid-state conditions. Degradation of different components, i.e., hemicellulose, cellulose and lignin was evaluated along with nutritional parameters including; in vitro digestibility, crude protein, amino acids, total phenolic contents (TPC) etc. Effect of nitrogen-rich supplements on degradation of lignocellulosics was evaluated using two best selected fungal strains (Phlebia brevispora and Phlebia floridensis). The best selected conditions were used to upscale the process up to 200 g batches of wheat and PS. Lignin was selectively degraded up to 30 % with a limited loss of 11-12 % in total organic matter. Finally, the degraded agro-residues demonstrated 50-62 % enhancement in their digestibility. Two-threefold enhancement in other nutritional quality (amino acids, TPCs and antioxidant activity) fortifies the process. Thus the method is quite helpful to design an effective solid-state fermentation system to improve the nutritive quality of agricultural residues by simultaneous production of lignocellulolytic enzyme production and antioxidants.

Oxidation of clofibric acid in aqueous solution using a non-thermal plasma discharge or gamma radiation

NASA Astrophysics Data System (ADS)

Madureira, Joana; Ceriani, Elisa; Pinhão, Nuno; Marotta, Ester; Melo, Rita; Cabo Verde, Sandra; Paradisi, Cristina; Margaça, Fernanda M. A.

2017-11-01

In this work, we study degradation of clofibric acid (CFA) in aqueous solution using either ionizing radiation from a $^{60}$Co source or a non-thermal plasma produced by discharges in the air above the solution. The results obtained with the two technologies are compared in terms of effectiveness of CFA degradation and its by-products. In both cases the CFA degradation follows a quasi-exponential decay in time well modelled by a kinetic scheme which considers the competition between CFA and all reaction intermediates for the reactive species generated in solution as well as the amount of the end product formed. A new degradation law is deduced to explain the results. Although the end-product CO$_2$ was detected and the CFA conversion found to be very high under the studied conditions, HPLC analysis reveals several degradation intermediates still bearing the aromatic ring with the chlorine substituent. The extent of mineralization is rather limited. The energy yield is found to be higher in the gamma radiation experiments.

Oxidation of clofibric acid in aqueous solution using a non-thermal plasma discharge or gamma radiation.

PubMed

Madureira, Joana; Ceriani, Elisa; Pinhão, Nuno; Marotta, Ester; Melo, Rita; Cabo Verde, Sandra; Paradisi, Cristina; Margaça, Fernanda M A

2017-11-01

In this work, we study degradation of clofibric acid (CFA) in aqueous solution using either ionizing radiation from a 60 Co source or a non-thermal plasma produced by discharges in the air above the solution. The results obtained with the two technologies are compared in terms of effectiveness of CFA degradation and its by-products. In both cases the CFA degradation follows a quasi-exponential decay in time well modelled by a kinetic scheme which considers the competition between CFA and all reaction intermediates for the reactive species generated in solution as well as the amount of the end product formed. A new degradation law is deduced to explain the results. Although the end-product CO 2 was detected and the CFA conversion found to be very high under the studied conditions, HPLC analysis reveals several degradation intermediates still bearing the aromatic ring with the chlorine substituent. The extent of mineralization is rather limited. The energy yield is found to be higher in the gamma radiation experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient degradation of Azo dyes by a newly isolated fungus Trichoderma tomentosum under non-sterile conditions.

PubMed

He, Xiao-Ling; Song, Chao; Li, Yuan-Yuan; Wang, Ning; Xu, Lei; Han, Xin; Wei, Dong-Sheng

2018-04-15

A fast-growing fungus with remarkable ability to degrade several azo dyes under non-sterile conditions was isolated and identified. This fungus was identified as Trichoderma tomentosum. Textile effluent of ten-fold dilution could be decolorized by 94.9% within 72h before optimization. Acid Red 3R model wastewater with a concentration of 85.5mgL -1 could be decolorized by 99.2% within the same time after optimization. High-level of manganese peroxidase and low-level of lignin peroxidase activities were detected during the process of decolorization from the culture supernatant, indicating the possible involvement of two enzymes in azo dye decolorization. No aromatic amine products were detected from the degradation products of Acid Red 3R by gas chromatography-mass spectrometry (GC/MS) analysis, indicating the possible involvement of a special symmetrical oxidative degradation pathway. Phytotoxicity assay confirmed the lower toxicity toward the test plant seeds of the degradation products when compared to the original dye. Copyright © 2017 Elsevier Inc. All rights reserved.

Thermal stability, antioxidant, and anti-inflammatory activity of curcumin and its degradation product 4-vinyl guaiacol.

PubMed

Esatbeyoglu, Tuba; Ulbrich, Katrin; Rehberg, Clemens; Rohn, Sascha; Rimbach, Gerald

2015-03-01

Curcumin is a secondary plant metabolite present in Curcuma longa L. Since curcumin is widely used as a food colorant in thermally processed food it may undergo substantial chemical changes which in turn could affect its biological activity. In the current study, curcumin was roasted at 180 °C up to 70 minutes and its kinetic of degradation was analyzed by means of HPLC-PDA and LC-MS, respectively. Roasting of curcumin resulted in the formation of the degradation products vanillin, ferulic acid, and 4-vinyl guaiacol. In cultured hepatocytes roasted curcumin as well as 4-vinyl guaiacol enhanced the transactivation of the redox-regulated transcription factor Nrf2, known to be centrally involved in cellular stress response and antioxidant defense mechanisms. The antioxidant enzyme paraoxonase 1 was induced by roasted curcumin and 4-vinyl guaiacol. Furthermore, roasted curcumin and 4-vinyl guaiacol decreased interleukin-6 gene expression in lipopolysaccharide stimulated murine macrophages. Current data suggest that curcumin undergoes degradation due to roasting and its degradation product exhibit significant biological activity in cultured cells.

A process for complete biodegradation of shrimp waste by a novel marine isolate Paenibacillus sp. AD with simultaneous production of chitinase and chitin oligosaccharides.

PubMed

Kumar, Aditya; Kumar, Deepak; George, Nancy; Sharma, Prince; Gupta, Naveen

2018-04-01

Disposal of chitinaceous waste is a major problem of seafood industry. Most of the known chitinolytic organisms have been studied with respect to pure chitin as substrate. Use of these organisms for degradation of seafood waste has not been explored much. In present study a marine bacterium capable of proficiently degrading shrimp waste with co-production of value added products like chitinase and chitin oligosaccharides was isolated from seafood waste dumping sites. On 16s rRNA and biochemical analysis bacterium was found to be a novel species of genus Paenibacillus.Under optimized condition complete shrimp waste degradation (99%) was achieved along with chitinase yield of 20.01 IUml -1 . SEM and FTIR showed the structural changes and breakage of bonds typical to that of chitin, which indicated that this process can be used for the degradation of other chitinaceous material also. Thin layer chromatography revealed the presence of chitin oligosaccharides of various degree of polymerization in the hydrolysate. Complete degradation of shrimp waste by Paenibacillus sp. AD makes it a potential candidate for the bioremediation of seafood waste at large scale. Concomitant production of chitinase and chitin oligosaccharides further makes the process economical and commercially viable. Copyright © 2017 Elsevier B.V. All rights reserved.

Rolling-made gas diffusion electrode with carbon nanotube for electro-Fenton degradation of acetylsalicylic acid.

PubMed

Yang, Huijia; Zhou, Minghua; Yang, Weilu; Ren, Gengbo; Ma, Liang

2018-05-04

H 2 O 2 production plays an important role in electro-Fenton process for pharmaceutical and personal care products (PPCPs) degradation. In this work, carbon nanotube (CNT) was attempted to make a gas diffusion electrode (GDE) by rolling method to achieve a high H 2 O 2 production and current efficiency, and it was further used as electro-Fenton cathode for the degradation of acetylsalicylic acid (ASA) as one kind of PPCPs. The optimal amount of catalyst layer was 0.15 g CNT and 93.75 μL PTFE, obtaining the production of H 2 O 2 of 805 mg L -1 in 0.05 mM Na 2 SO 4 solution at 100 mA after 180 min. The degradation of ASA by electro-Fenton on such a CNT-GDE cathode was studied, and some important parameters such as current, pH as well as the dosage of Fe 2+ were optimized. The degradation ratio of ASA could achieve almost 100% after 10 min and the TOC removal ratio was 62% at 1 h under the condition of 100 mA and pH 3, showing a great potential for the treatment of PPCPs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Development of a cellularly degradable PEG hydrogel to promote articular cartilage extracellular matrix deposition.

PubMed

Sridhar, Balaji V; Brock, John L; Silver, Jason S; Leight, Jennifer L; Randolph, Mark A; Anseth, Kristi S

2015-04-02

Healing articular cartilage remains a significant clinical challenge because of its limited self-healing capacity. While delivery of autologous chondrocytes to cartilage defects has received growing interest, combining cell-based therapies with scaffolds that capture aspects of native tissue and promote cell-mediated remodeling could improve outcomes. Currently, scaffold-based therapies with encapsulated chondrocytes permit matrix production; however, resorption of the scaffold does not match the rate of production by cells leading to generally low extracellular matrix outputs. Here, a poly (ethylene glycol) (PEG) norbornene hydrogel is functionalized with thiolated transforming growth factor (TGF-β1) and cross-linked by an MMP-degradable peptide. Chondrocytes are co-encapsulated with a smaller population of mesenchymal stem cells, with the goal of stimulating matrix production and increasing bulk mechanical properties of the scaffold. The co-encapsulated cells cleave the MMP-degradable target sequence more readily than either cell population alone. Relative to non-degradable gels, cellularly degraded materials show significantly increased glycosaminoglycan and collagen deposition over just 14 d of culture, while maintaining high levels of viability and producing a more widely-distributed matrix. These results indicate the potential of an enzymatically degradable, peptide-functionalized PEG hydrogel to locally influence and promote cartilage matrix production over a short period. Scaffolds that permit cell-mediated remodeling may be useful in designing treatment options for cartilage tissue engineering applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Sensor-Based Method for Diagnostics of Machine Tool Linear Axes.

PubMed

Vogl, Gregory W; Weiss, Brian A; Donmez, M Alkan

2015-01-01

A linear axis is a vital subsystem of machine tools, which are vital systems within many manufacturing operations. When installed and operating within a manufacturing facility, a machine tool needs to stay in good condition for parts production. All machine tools degrade during operations, yet knowledge of that degradation is illusive; specifically, accurately detecting degradation of linear axes is a manual and time-consuming process. Thus, manufacturers need automated and efficient methods to diagnose the condition of their machine tool linear axes without disruptions to production. The Prognostics and Health Management for Smart Manufacturing Systems (PHM4SMS) project at the National Institute of Standards and Technology (NIST) developed a sensor-based method to quickly estimate the performance degradation of linear axes. The multi-sensor-based method uses data collected from a 'sensor box' to identify changes in linear and angular errors due to axis degradation; the sensor box contains inclinometers, accelerometers, and rate gyroscopes to capture this data. The sensors are expected to be cost effective with respect to savings in production losses and scrapped parts for a machine tool. Numerical simulations, based on sensor bandwidth and noise specifications, show that changes in straightness and angular errors could be known with acceptable test uncertainty ratios. If a sensor box resides on a machine tool and data is collected periodically, then the degradation of the linear axes can be determined and used for diagnostics and prognostics to help optimize maintenance, production schedules, and ultimately part quality.

Mass spectrometric identification and toxicity assessment of degraded products of aflatoxin B1 and B2 by Corymbia citriodora aqueous extracts

PubMed Central

Iram, Wajiha; Anjum, Tehmina; Iqbal, Mazhar; Ghaffar, Abdul; Abbas, Mateen

2015-01-01

This study explores the detoxification potential of Corymbia citriodora plant extracts against aflatoxin B1 and B2 (AFB1; 100 μg L−1 and AFB2; 50 μg L−1) in In vitro and In vivo assays. Detoxification was qualitatively and quantitatively analyzed by TLC and HPLC, respectively. The study was carried out by using different parameters of optimal temperature, pH and incubation time period. Results indicated that C. citriodora leaf extract(s) more effectively degrade AFB1 and AFB2 i.e. 95.21% and 92.95% respectively than C. citriodora branch extract, under optimized conditions. The structural elucidation of degraded toxin products was done by LCMS/MS analysis. Ten degraded products of AFB1 and AFB2 and their fragmentation pathways were proposed based on molecular formulas and MS/MS spectra. Toxicity of these degraded products was significantly reduced as compared to that of parent compounds because of the removal of double bond in the terminal furan ring. The biological toxicity of degraded toxin was further analyzed by brine shrimps bioassay, which showed that only 17.5% mortality in larvae was recorded as compared to untreated toxin where 92.5% mortality was observed after 96hr of incubation. Therefore, our finding suggests that C. citriodora leaf extract can be used as an effective tool for the detoxification of aflatoxins. PMID:26423838

THE DELICATE BALANCE BETWEEN SECRETED PROTEIN FOLDING AND ENDOPLASMIC RETICULUM-ASSOCIATED DEGRADATION IN HUMAN PHYSIOLOGY

PubMed Central

Guerriero, Christopher J.; Brodsky, Jeffrey L.

2014-01-01

Protein folding is a complex, error-prone process that often results in an irreparable protein by-product. These by-products can be recognized by cellular quality control machineries and targeted for proteasome-dependent degradation. The folding of proteins in the secretory pathway adds another layer to the protein folding “problem,” as the endoplasmic reticulum maintains a unique chemical environment within the cell. In fact, a growing number of diseases are attributed to defects in secretory protein folding, and many of these by-products are targeted for a process known as endoplasmic reticulum-associated degradation (ERAD). Since its discovery, research on the mechanisms underlying the ERAD pathway has provided new insights into how ERAD contributes to human health during both normal and diseases states. Links between ERAD and disease are evidenced from the loss of protein function as a result of degradation, chronic cellular stress when ERAD fails to keep up with misfolded protein production, and the ability of some pathogens to coopt the ERAD pathway. The growing number of ERAD substrates has also illuminated the differences in the machineries used to recognize and degrade a vast array of potential clients for this pathway. Despite all that is known about ERAD, many questions remain, and new paradigms will likely emerge. Clearly, the key to successful disease treatment lies within defining the molecular details of the ERAD pathway and in understanding how this conserved pathway selects and degrades an innumerable cast of substrates. PMID:22535891

A Sensor-Based Method for Diagnostics of Machine Tool Linear Axes

PubMed Central

Vogl, Gregory W.; Weiss, Brian A.; Donmez, M. Alkan

2017-01-01

A linear axis is a vital subsystem of machine tools, which are vital systems within many manufacturing operations. When installed and operating within a manufacturing facility, a machine tool needs to stay in good condition for parts production. All machine tools degrade during operations, yet knowledge of that degradation is illusive; specifically, accurately detecting degradation of linear axes is a manual and time-consuming process. Thus, manufacturers need automated and efficient methods to diagnose the condition of their machine tool linear axes without disruptions to production. The Prognostics and Health Management for Smart Manufacturing Systems (PHM4SMS) project at the National Institute of Standards and Technology (NIST) developed a sensor-based method to quickly estimate the performance degradation of linear axes. The multi-sensor-based method uses data collected from a ‘sensor box’ to identify changes in linear and angular errors due to axis degradation; the sensor box contains inclinometers, accelerometers, and rate gyroscopes to capture this data. The sensors are expected to be cost effective with respect to savings in production losses and scrapped parts for a machine tool. Numerical simulations, based on sensor bandwidth and noise specifications, show that changes in straightness and angular errors could be known with acceptable test uncertainty ratios. If a sensor box resides on a machine tool and data is collected periodically, then the degradation of the linear axes can be determined and used for diagnostics and prognostics to help optimize maintenance, production schedules, and ultimately part quality. PMID:28691039

Radiosterilization of drugs in aqueous solutions may be achieved by the use of radioprotective excipients.

PubMed

Maquille, Aubert; Jiwan, Jean-Louis Habib; Tilquin, Bernard

2008-02-12

The aim of this study was to assess the feasibility of radiosterilization of drugs aqueous solutions and to evaluate the effects of some additives, such as mannitol, nicotinamide and pyridoxine, which might protect the drug from degradation. Metoclopramide was selected as a model drug. The structures of the degradation products were determined to gain insight on the radiolysis mechanisms in aqueous solution in order to design strategies to lower the drug degradation. Metoclopramide hydrochloride aqueous solutions with and without excipients were irradiated either with gamma rays or high-energy electrons. HPLC-DAD was used to measure the loss of chemical potency and to quantify the degradation products which were also characterized by LC-APCI-MS-MS. Metoclopramide recovery for gamma and electron beam-irradiated solutions containing either mannitol, pyridoxine or nicotinamide meets the pharmacopoeial specifications for metoclopramide content up to a 15 kGy irradiation so that metoclopramide solutions containing these excipients might be radiosterilized at 15 kGy either with gamma rays or high-energy electrons. Structures are proposed for the majority of radiolysis products. Similar radiolysis products were detected for gamma and electron beam irradiations but the chromatographic profiles were different (differences in the distribution of radiolysis products).

Degradation of Diuron by Phanerochaete chrysosporium: Role of Ligninolytic Enzymes and Cytochrome P450

PubMed Central

Coelho-Moreira, Jaqueline da Silva; de Souza, Aline Cristine da Silva; Oliveira, Roselene Ferreira; de Sá-Nakanishi, Anacharis Babeto; de Souza, Cristina Giatti Marques; Peralta, Rosane Marina

2013-01-01

The white-rot fungus Phanerochaete chrysosporium was investigated for its capacity to degrade the herbicide diuron in liquid stationary cultures. The presence of diuron increased the production of lignin peroxidase in relation to control cultures but only barely affected the production of manganese peroxidase. The herbicide at the concentration of 7 μg/mL did not cause any reduction in the biomass production and it was almost completely removed after 10 days. Concomitantly with the removal of diuron, two metabolites, DCPMU [1-(3,4-dichlorophenyl)-3-methylurea] and DCPU [(3,4-dichlorophenyl)urea], were detected in the culture medium at the concentrations of 0.74 μg/mL and 0.06 μg/mL, respectively. Crude extracellular ligninolytic enzymes were not efficient in the in vitro degradation of diuron. In addition, 1-aminobenzotriazole (ABT), a cytochrome P450 inhibitor, significantly inhibited both diuron degradation and metabolites production. Significant reduction in the toxicity evaluated by the Lactuca sativa L. bioassay was observed in the cultures after 10 days of cultivation. In conclusion, P. chrysosporium can efficiently metabolize diuron without the accumulation of toxic products. PMID:24490150

Application of carbohydrate arrays coupled with mass spectrometry to detect activity of plant-polysaccharide degradative enzymes from the fungus Aspergillus niger.

PubMed

van Munster, Jolanda M; Thomas, Baptiste; Riese, Michel; Davis, Adrienne L; Gray, Christopher J; Archer, David B; Flitsch, Sabine L

2017-02-21

Renewables-based biotechnology depends on enzymes to degrade plant lignocellulose to simple sugars that are converted to fuels or high-value products. Identification and characterization of such lignocellulose degradative enzymes could be fast-tracked by availability of an enzyme activity measurement method that is fast, label-free, uses minimal resources and allows direct identification of generated products. We developed such a method by applying carbohydrate arrays coupled with MALDI-ToF mass spectrometry to identify reaction products of carbohydrate active enzymes (CAZymes) of the filamentous fungus Aspergillus niger. We describe the production and characterization of plant polysaccharide-derived oligosaccharides and their attachment to hydrophobic self-assembling monolayers on a gold target. We verify effectiveness of this array for detecting exo- and endo-acting glycoside hydrolase activity using commercial enzymes, and demonstrate how this platform is suitable for detection of enzyme activity in relevant biological samples, the culture filtrate of A. niger grown on wheat straw. In conclusion, this versatile method is broadly applicable in screening and characterisation of activity of CAZymes, such as fungal enzymes for plant lignocellulose degradation with relevance to biotechnological applications as biofuel production, the food and animal feed industry.

Removal of PCB and Other Halogenated Organic Contaminants found in Ex Situ Structures

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline (Inventor); Clausen, Christian (Inventor); Geiger, Cherie L. (Inventor); Coon, Christina (Inventor); Berger, Cristina M. (Inventor); Filipek, Laura B. (Inventor); Milum, Kristen M. (Inventor)

2007-01-01

Emulsified systems or a surfactant-stabilized, biodegradable water-in-solvent emulsion with bimetallic particles contained with the emulsion droplets are useful at removing PCBs from ex situ structures. The hydrophobic emulsion system draws PCBs through the solvent/surfactant membrane. Once inside the membrane, the PCBs diffuse into the bimetallic particles and undergo degradation. The PCBs continue to enter, diffuse, degrade, and biphenyl will exit the particle maintaining a concentration gradient across the membrane and maintaining a driving force of the reaction.

Removal of PCB and other halogenated organic contaminants found in ex situ structures

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline (Inventor); Clausen, Christian (Inventor); Geiger, Cherie L. (Inventor); Coon, Christina (Inventor); Berger, Cristina M. (Inventor); Filipek, Laura B. (Inventor); Milum, Kristen M. (Inventor)

2007-01-01

Emulsified systems of a surfactant-stabilized, biodegradable water-in-solvent emulsion with bimetallic particles contained with the emulsion droplets are useful at removing PCBs from ex situ structures. The hydrophobic emulsion system draws PCBs through the solvent/surfactant membrane. Once inside the membrane, the PCBs diffuse into the bimetallic particles and undergo degradation. The PCBs continue to enter, diffuse, degrade, and biphenyl will exit the particle maintaining a concentration gradient across the membrane and maintaining a driving force of the reaction.

Removal of PCB and other halogenated organic contaminants found in ex situ structures

NASA Technical Reports Server (NTRS)

Clausen, Christian A. (Inventor); Milum, Kristen M. (Inventor); Quinn, Jacqueline W. (Inventor); Berger, Cristina M. (Inventor); Geiger, Cherie L. (Inventor); Filipek, Laura B. (Inventor); Coon, Christina (Inventor)

2009-01-01

Emulsified systems of a surfactant-stabilized, biodegradable water-in-solvent emulsion with bimetallic particles contained with the emulsion droplets are useful at removing PCBs from ex situ structures. The hydrophobic emulsion system draws PCBs through the solvent/surfactant membrane. Once inside the membrane, the PCBs diffuse into the bimetallic particles and undergo degradation. The PCBs continue to enter, diffuse, degrade, and biphenyl will exit the particle maintaining a concentration gradient across the membrane and maintaining a driving force of the reaction.

Consistent forcing scheme in the cascaded lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Fei, Linlin; Luo, Kai Hong

2017-11-01

In this paper, we give an alternative derivation for the cascaded lattice Boltzmann method (CLBM) within a general multiple-relaxation-time (MRT) framework by introducing a shift matrix. When the shift matrix is a unit matrix, the CLBM degrades into an MRT LBM. Based on this, a consistent forcing scheme is developed for the CLBM. The consistency of the nonslip rule, the second-order convergence rate in space, and the property of isotropy for the consistent forcing scheme is demonstrated through numerical simulations of several canonical problems. Several existing forcing schemes previously used in the CLBM are also examined. The study clarifies the relation between MRT LBM and CLBM under a general framework.

Force dependence of phagosome trafficking in retinal pigment epithelial cells

NASA Astrophysics Data System (ADS)

Daniel, Rebekah; Koll, Andrew T.; Altman, David

2014-09-01

Retinal pigment epithelial (RPE) cells play an integral role in the renewal of photoreceptor disk membranes. As rod and cone cells shed their outer segments, they are phagocytosed and degraded by the RPE, and a failure in this process can result in retinal degeneration. We have studied the role of myosin VI in nonspecific phagocytosis in a human RPE primary cell line (ARPE-19), testing the hypothesis that this motor generates the forces required to traffic phagosomes in these cells. Experiments were conducted in the presence of forces through the use of in vivo optical trapping. Our results support a role for myosin VI in phagosome trafficking and demonstrate that applied forces modulate rates of phagosome trafficking.

Evaluation of degradation of antibiotic tetracycline in pig manure by electron beam irradiation.

PubMed

Cho, Jae-Young

2010-04-01

This study was carried out to evaluate the degradation efficiency and intermediate products of the tetracycline from artificially contaminated pig manure using of electron beam irradiation as a function of the absorbed dose. The degradation efficiency of tetracycline was 42.77% at 1 kGy, 64.20% at 3 kGy, 77.83% at 5 kGy, and 90.50% at 10 kGy. The initial concentration of tetracycline (300 mg kg(-1)) in pig manure decreased significantly to 24.2 +/- 5.3 mg kg(-1) after electron beam irradiation at 10 kGy. The radiolytic degradation products of tetracycline were 1,4-benzenedicarboxylic acid, hexadecanoic acid, 9-octadecenamide, 11-octadecenamide, and octadecanoic acid.

Development of a pressurized liquid extraction-solid-phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry method for the quantitative determination of benzoxazolinones and their degradation products in agricultural soil.

PubMed

Villagrasa, M; Guillamón, M; Navarro, A; Eljarrat, E; Barceló, D

2008-02-01

A new analytical method for the quantitative determination of benzoxazolinones and their degradation products in agricultural soils based on the use of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) and then instrumental determination using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) is described. Using this method, the characterization, separation and quantitative detection of a mixture of two benzoxazolinones, benzoxazolin-2-one (BOA) and 6-methoxybenzoxazolin-2-one (MBOA) and their degradation products, 2-aminophenol (APH), N-(2-hydroxyphenyl)malonamic acid (HMPMA), 2-amino-3-H-phenoxazin-3-one (APO), 9-methoxy-2-amino-3-H-phenoxazin-3-one (AMPO), 2-acetylamino-3-H-phenoxazin-3-one (AAPO) and 2-acetylamino-9-methoxy-2-amino-3-H-phenoxazin-3-one (AAMPO) was achieved. The complete LC-ESI-MS-MS precursor-product ion fragmentation pathways for the degradation products of benzoxazolinones are described for the first time. Quantitative analysis was done in the multiple reaction mode using two specific combinations of precursor-product ion transitions for each compound. The optimized method was quality assessed by the measure of parameter as recovery, linearity, sensitivity, repeatability and reproducibility. Recoveries of the analytes ranged from 53 to 123%. The developed method offered improvements to the sensitivity as compared with our previously LC-MS method, with detection limits down to 2.4-21 ng/g of dry weight. This achievement allows us to identify and quantify for the first time degradation products of benzoxazolinones in real agricultural soil samples. Analytes were found in the range of 20.6-149 ng/g dry weight.

Industrially Important Carbohydrate Degrading Enzymes from Yeasts: Pectinases, Chitinases, and β-1,3-Glucanases

NASA Astrophysics Data System (ADS)

Gummadi, Sathyanarayana N.; Kumar, D. Sunil; Dash, Swati S.; Sahu, Santosh Kumar

Polysaccharide degrading enzymes are hydrolytic enzymes, which have a lot of industrial potential and also play a crucial role in carbon recycling. Pectinases, chitinases and glucanases are the three major polysaccharide degrading enzymes found abundantly in nature and these enzymes are mainly produced by fungal strains. Production of these enzymes by yeasts is advantageous over fungi, because the former are easily amenable to genetic manipulations and time required for growth and production is less than that of the latter. Several yeasts belonging to Saccharomyces, Pichia, Rhodotorula and Cryptococcus produce extracellular pectinases, glucanases and chitinases. This chapter emphasizes on the biological significance of these enzymes, their production and their industrial applications.

Characterization of a low-level unknown isomeric degradation product using an integrated online-offline top-down tandem mass spectrometry platform.

PubMed

Yu, Xiang; Warme, Christopher; Lee, Dinah; Zhang, Jing; Zhong, Wendy

2013-10-01

An integrated online-offline platform was developed combining automated online LC-MS fraction collection, continuous accumulation of selected ions (CASI), and offline top-down electron capture dissociation (ECD) tandem mass spectrometry experiments to identify a low-level, unknown isomeric degradant in a formulated drug product during an accelerated stability study. By identifying the diagnostic ions of the isoaspartic acid (isoAsp), the top-down ECD experiment showed that the Asp9 in exenatide was converted to isoAsp9 to form the unknown isomeric degradant. The platform described here provides an accurate, straightforward, and low limit of detection method for the analysis of Asp isomerization as well as other potential low-level degradants in therapeutic polypeptides and proteins. It is especially useful for unstable and time-sensitive degradants and impurities.

Composition analysis and application of degradation products of whole feathers through a large scale of fermentation.

PubMed

Cao, Zhang-Jun; Lu, Dan; Luo, Lai-Sheng; Deng, Yun-Xia; Bian, Yong-Gang; Zhang, Xing-Qun; Zhou, Mei-Hua

2011-08-01

Feathers are one of the most abundant bioresources. They are discarded as waste in most cases and could cause environmental pollution. On the other hand, keratin constituted by amino acids is the main component of feathers. In this article, we reported on biorefined feathers and integrants and application of degraded products. The fermentation of whole chicken feathers with Stenotrophomonas maltophilia DHHJ in a scale-up of a 5-L bioreactor was investigated in this article. The fermentation process was controlled at 0.08 MPa pressure, 2.5 L/min airflow, and 300 rpm as 100% oxygen saturation level, 40°C, and pH 7.8. Feathers were almost completely degraded in the tested fermentation reaction with the following conditions: 80 g of whole feathers in 3 L fermentation broth for 72 h, seed age of 16 h, 100 mL inoculation amount, and 50% oxygen saturation level. The degraded products contain 397.1 mg/L soluble protein that has mass weight ranging from 10 to 160 kD, 336.9 mg/L amino acids, and many kinds of metal ions. The fermentation broth was evaluated as leaf fertilizer and found to increase plant growth to 82% or 66% for two- or fourfold dilutions, respectively. In addition, in a hair care assay, the broth showed a hair protective function by increasing weight, flexibility, and strength of the treated hair. The whole feathers were degraded completely by S. maltophilia DHHJ. The degraded product includes many factors to life, such as peptides, amino acids, and mineral elements. It could be applied as leaf fertilizer and hair care product.

Toxicological Impacts of Pharmaceuticals and Personal Care Products on Water Quality: Environmental Fate, Transformation and Health Effects

NASA Astrophysics Data System (ADS)

Rubasinghege, G. R. S.; Rijal, H.; Gurung, R.; Maldonado-Torres, S.; Rogelj, S.; Piyasena, M.

2016-12-01

The growing medical and personal needs of the human population have escalated release of pharmaceuticals and personal care products (PPCPs) to the nature. The current work investigated abiotic degradation pathways of selected PPCPs in the presence of major mineral components of soil and the acute health effects of degraded PPCPs. Degradation of selected PPCPs (ibuprofen and clofibric acid) was carried out using custom-built glass reactors in batch studies. The secondary products of PPCPs were analyzed and identified using modified HPLC and LC-MS methods. Results from these studies showed that the extent of degradation depends on the type of the clay or mineral oxide, and solar radiation. In the absence of solar radiation (night time chemistry), the dominant reaction mechanism was observed to be the adsorption of PPCPs on to clay particles where surface functional groups and particle size play a key role. In contrast, under solar radiation, PPCPs break down to several fractions in the presence of clay particles. The decay rates were at least 3-fold higher for irradiated samples compared to that of dark conditions. Acute toxicity of selected PPCPs and their degradation products were tested on three microorganisms: gram-positive soil bacteria, Bacillus megaterium; gram-negative marine bacteria, Pseudoaltermonas atlantica; and algae from the Chlorella genus. Growth inhibition was measured using optical density measurements, MTT viability assay, and flow cytometer. The results suggest that the concentrations of primary compounds, Ibuprofen and Clofibric Acid, found in the environment that ranges from μg/L to ng/L are not sufficient to inhibit growth of either three microorganisms. However, selected organisms showed significant differences in sensitivity to degraded products. Results from current work advance our knowledge and understanding in the fields of environmental toxicology, chemistry in aqueous phases, and geochemistry.