Comparing Methods for Assessing Reliability Uncertainty Based on Pass/Fail Data Collected Over Time

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

Abes, Jeff I.; Hamada, Michael S.; Hills, Charles R.

In this paper, we compare statistical methods for analyzing pass/fail data collected over time; some methods are traditional and one (the RADAR or Rationale for Assessing Degradation Arriving at Random) was recently developed. These methods are used to provide uncertainty bounds on reliability. We make observations about the methods' assumptions and properties. Finally, we illustrate the differences between two traditional methods, logistic regression and Weibull failure time analysis, and the RADAR method using a numerical example.

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.

[Studies on the degradation of paracetamol in sono-electrochemical oxidation].

PubMed

Dai, Qi-Zhou; Ma, Wen-Jiao; Shen, Hong; Chen, Jun; Chen, Jian-Meng

2012-07-01

A novel lead dioxide electrodes co-doped with rare earth and polytetrafluoroethylene (PTFE) were prepared by the electrode position method and applied as anodes in sono-electrochemical oxidation for pharmaceutical wastewater degradation. The results showed that the APAP removal and the mineralization efficiency reached an obvious increase, which meant that the catalytic efficiency showed a significant improvement in the use of rare-earth doped electrode. The effects of process factors showed that the condition of the electrode had the best degradation efficiency with doped with Ce2O3 under electrolyte concentration of 14.2 g x L(-1), 49.58 W x cm(-2), 50 Hz, pH = 3, 71.43 mA x cm(-2). The APAP of 500 mg x L(-1) removal rate reached 92.20% and its COD and TOC values declined to 79.95% and 58.04%, the current efficiency reached 45.83% after degradation process for 2.0 h. The intermediates were monitored by the methods of GC-MS, HPLC, and IC. The main intermediates of APAP were p-benzoquinone, benzoic acid, acetic acid, maleic acid, oxalic acid, formic acid etc, and the final products were carbon dioxide and water. The goal of completely degradation of pollutant was achieved and a possible degradation way was proposed.

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.

Retrieve polarization aberration from image degradation: a new measurement method in DUV lithography

NASA Astrophysics Data System (ADS)

Xiang, Zhongbo; Li, Yanqiu

2017-10-01

Detailed knowledge of polarization aberration (PA) of projection lens in higher-NA DUV lithographic imaging is necessary due to its impact to imaging degradations, and precise measurement of PA is conductive to computational lithography techniques such as RET and OPC. Current in situ measurement method of PA thorough the detection of degradations of aerial images need to do linear approximation and apply the assumption of 3-beam/2-beam interference condition. The former approximation neglects the coupling effect of the PA coefficients, which would significantly influence the accuracy of PA retrieving. The latter assumption restricts the feasible pitch of test masks in higher-NA system, conflicts with the Kirhhoff diffraction model of test mask used in retrieving model, and introduces 3D mask effect as a source of retrieving error. In this paper, a new in situ measurement method of PA is proposed. It establishes the analytical quadratic relation between the PA coefficients and the degradations of aerial images of one-dimensional dense lines in coherent illumination through vector aerial imaging, which does not rely on the assumption of 3-beam/2- beam interference and linear approximation. In this case, the retrieval of PA from image degradation can be convert from the nonlinear system of m-quadratic equations to a multi-objective quadratic optimization problem, and finally be solved by nonlinear least square method. Some preliminary simulation results are given to demonstrate the correctness and accuracy of the new PA retrieving model.

Tiros IV Radiation Data Catalog and Users' Manual

NASA Technical Reports Server (NTRS)

Kunde, V. G.

1963-01-01

The TIROS IV Meteorological Satellite contains a medium resolution scanning radiometer. Two of the channels of this instrument are sensitive to reflected solar radiation and the remaining two respond to emitted thermal radiation from the earth and its atmosphere. The two thermal channels are calibrated in terms of equivalent blackbody temperatures, and the reflected solar radiation channels in terms of effective radiant emittances. The calibration data, along with orbital and attitude data and the radiation data from the satellite, were incorporated in a computer program for an IBM 7090 which was used to produce, in binary form, the "Final Meteorological Radiation Tape" which is the basic repository of all radiation data. After launch, the radiometer displaye d the same degradation of response characteristics as did its predecessors in TIROS II and TIROS III. The onset of degradation results in a departure of the data from the prelaunch laboratory calibration. The cause of degradation has not been determined, and the matter is still being studied at the Goddard Space Flight Center. Before work with the TIROS IV radiation data is attempted, an understanding of the radiometer, its calibration, and the problems encountered in the experiment, especially from response degradation, is essential. The instrumentation design, development work, and the calibrations herein described were performed by the Goddard Space Flight Center Staff, whereas the computer and programming efforts were carried out jointly by the staffs of the National Weather Satellite Center, U. S. Weather Bureau, and the Goddard Space Flight Center. In this Catalog-Manual, the radiometer an d its calibration, data processing, the "Final Meteorological Radiation Tape", the observed degradation patterns, and possible corrections for degradation are discussed. The Catalog-Manual also includes, in two forms, documentation of each orbit of successfully reduced radiation data acquired by TIROS IV. One method of presentation is the Index of Final Meteorological Radiation Tapes and the other is a Subpoint Track, Summary of Available Radiation Data in diagrammatic form.

Blind estimation of blur in hyperspectral images

NASA Astrophysics Data System (ADS)

Zhang, Mo; Vozel, Benoit; Chehdi, Kacem; Uss, Mykhail; Abramov, Sergey; Lukin, Vladimir

2017-10-01

Hyperspectral images acquired by remote sensing systems are generally degraded by noise and can be sometimes more severely degraded by blur. When no knowledge is available about the degradations present on the original image, blind restoration methods can only be considered. By blind, we mean absolutely no knowledge neither of the blur point spread function (PSF) nor the original latent channel and the noise level. In this study, we address the blind restoration of the degraded channels component-wise, according to a sequential scheme. For each degraded channel, the sequential scheme estimates the blur point spread function (PSF) in a first stage and deconvolves the degraded channel in a second and final stage by means of using the PSF previously estimated. We propose a new component-wise blind method for estimating effectively and accurately the blur point spread function. This method follows recent approaches suggesting the detection, selection and use of sufficiently salient edges in the current processed channel for supporting the regularized blur PSF estimation. Several modifications are beneficially introduced in our work. A new selection of salient edges through thresholding adequately the cumulative distribution of their corresponding gradient magnitudes is introduced. Besides, quasi-automatic and spatially adaptive tuning of the involved regularization parameters is considered. To prove applicability and higher efficiency of the proposed method, we compare it against the method it originates from and four representative edge-sparsifying regularized methods of the literature already assessed in a previous work. Our attention is mainly paid to the objective analysis (via ݈l1-norm) of the blur PSF error estimation accuracy. The tests are performed on a synthetic hyperspectral image. This synthetic hyperspectral image has been built from various samples from classified areas of a real-life hyperspectral image, in order to benefit from realistic spatial distribution of reference spectral signatures to recover after synthetic degradation. The synthetic hyperspectral image has been successively degraded with eight real blurs taken from the literature, each of a different support size. Conclusions, practical recommendations and perspectives are drawn from the results experimentally obtained.

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.

Degradation Prediction Model Based on a Neural Network with Dynamic Windows

PubMed Central

Zhang, Xinghui; Xiao, Lei; Kang, Jianshe

2015-01-01

Tracking degradation of mechanical components is very critical for effective maintenance decision making. Remaining useful life (RUL) estimation is a widely used form of degradation prediction. RUL prediction methods when enough run-to-failure condition monitoring data can be used have been fully researched, but for some high reliability components, it is very difficult to collect run-to-failure condition monitoring data, i.e., from normal to failure. Only a certain number of condition indicators in certain period can be used to estimate RUL. In addition, some existing prediction methods have problems which block RUL estimation due to poor extrapolability. The predicted value converges to a certain constant or fluctuates in certain range. Moreover, the fluctuant condition features also have bad effects on prediction. In order to solve these dilemmas, this paper proposes a RUL prediction model based on neural network with dynamic windows. This model mainly consists of three steps: window size determination by increasing rate, change point detection and rolling prediction. The proposed method has two dominant strengths. One is that the proposed approach does not need to assume the degradation trajectory is subject to a certain distribution. The other is it can adapt to variation of degradation indicators which greatly benefits RUL prediction. Finally, the performance of the proposed RUL prediction model is validated by real field data and simulation data. PMID:25806873

Development of large area nanostructured silicon-hydrogen alloy material with improved stability for solar cell application by argon dilution method

NASA Astrophysics Data System (ADS)

Dey, Arka; Das, Mrinmay; Datta, Joydeep; Jana, Rajkumar; Dhar, Joydeep; Sil, Sayantan; Biswas, Debasish; Banerjee, Chandan; Ray, Partha Pratim

2016-07-01

Here we have presented the results of large area (30 × 30 cm2) silicon-hydrogen alloy material and solar cell by argon dilution method. As an alternative to hydrogen dilution, argon dilution method has been applied to develop single junction solar cell with appreciable stability. Optimization of deposition conditions revealed that 95% argon dilution gives a nanostructured material with improved transport property and less light induced degradation. The minority carrier diffusion length (L d ) and mobility-lifetime (μτ) product of the material with 95% argon dilution degrades least after light soaking. Also the density of states (DOS) below conduction level reveals that this material is less defective. Solar cell with this argon diluted material has been fabricated with all the layers deposited by argon dilution method. Finally we have compared the argon diluted solar cell results with the optimized hydrogen diluted solar cell. Light soaking study proves that it is possible to develop stable solar cell on large area by argon dilution method and that the degradation of argon diluted solar cell is less than that of hydrogen diluted one. [Figure not available: see fulltext.

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

NASA Astrophysics Data System (ADS)

Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

2018-06-01

We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

Progressive Failure Analysis Methodology for Laminated Composite Structures

NASA Technical Reports Server (NTRS)

Sleight, David W.

1999-01-01

A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.

Photocatalytic removal of doxycycline from aqueous solution using ZnO nano-particles: a comparison between UV-C and visible light.

PubMed

Pourmoslemi, Shabnam; Mohammadi, Ali; Kobarfard, Farzad; Amini, Mohsen

2016-10-01

Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22(×10 -3 ) mg L -1 min -1 with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant k c and equilibrium adsorption constant K LH values calculated as 0.12 mg L -1 min -1 and 2.2 L mg -1 , respectively. Degradation of doxycycline was followed by UV-visible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products.

Vicarious calibration of GOES imager visible channel using the moon

USGS Publications Warehouse

Wu, X.; Stone, T.C.; Yu, F.; Han, D.

2006-01-01

In this paper, we study the feasibility of a method for vicarious calibration of the GOES Imager visible channel using the Moon. The measured Moon irradiance from 26 undipped moon imagers exhausted all the potential Moon appearances between July 1998 and December 2005, together with the seven scheduled Moon observation data obtained after November 2005, were compared with the USGS lunar model results to estimate the degradation rate of the GOES-10 Imager visible channel. A total of nine methods of determining the space count and identifying lunar pixels were employed in this study to measure the GOES-10 Moon irradiance. Our results show that the selected mean and the masking Moon appears the best method. Eight of the nine resulting degradation rates range from 4.5%/year to 5.0%/year during the nearly nine years of data, which are consistent with most other degradation rates obtained for GOES-10 based on different references. In particular, the degradation rate from the Moon-based calibration (4.5%/year) agrees very well with the MODIS-based calibration (4.4%/year) over the same period, confirming the capability of relative and absolute calibration based on the Moon. Finally, our estimate of lunar calibration precision as applied to GOES-10 is 3.5%.

Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

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

Darwish, Maher, E-mail: m-darwish@razi.tums.ac.ir; Mohammadi, Ali, E-mail: alimohammadi@tums.ac.ir; Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran

2016-02-15

Highlights: • PVP-stabilized CdS nanoparticles have been fabricated by a polyol-microwave method. • CdS nanoparticles were characterized and the size was approximately 48 ± 10 nm. • Catalytic activity of our nanoparticles was examined for tartrazine degradation. • Remarkable results were obtained under both UV and visible light irradiations. - Abstract: Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase andmore » 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.« less

Green remediation. Tool for safe and sustainable environment: a review

NASA Astrophysics Data System (ADS)

Singh, Mamta; Pant, Gaurav; Hossain, Kaizar; Bhatia, A. K.

2017-10-01

Nowadays, the bioremediation of toxic pollutants is a subject of interest in terms of health issues and environmental cleaning. In the present review, an eco-friendly, cost-effective approach is discussed for the detoxification of environmental pollutants by the means of natural purifier, i.e., blue-green algae over the conventional methods. Industrial wastes having toxic pollutants are not able to eliminate completely by existing the conventional techniques; in fact, these methods can only change their form rather than the entire degradation. These pollutants have an adverse effect on aquatic life, such as fauna and flora, and finally harm human life directly or indirectly. Cyanobacterial approach for the removal of this contaminant is an efficient tool for sustainable development and pollution control. Cyanobacteria are the primary consumers of food chain which absorbed complex toxic compounds from environments and convert them to simple nontoxic compounds which finally protect higher food chain consumer and eliminate risk of pollution. In addition, these organisms have capability to solve secondary pollution, as they can remediate radioactive compound, petroleum waste and degrade toxins from pesticides.

Degradation of components in drug formulations: a comparison between HPLC and DSC methods.

PubMed

Ceschel, G C; Badiello, R; Ronchi, C; Maffei, P

2003-08-08

Information about the stability of drug components and drug formulations is needed to predict the shelf-life of the final products. The studies on the interaction between the drug and the excipients may be carried out by means of accelerated stability tests followed by analytical determination of the active principle (HPLC and other methods) and by means of the differential scanning calorimetry (DSC). This research has been focused to the acetyl salicylic acid (ASA) physical-chemical characterisation by using DSC method in order to evaluate its compatibility with some of the most used excipients. It was possible to show, with the DSC method, the incompatibility of magnesium stearate with ASA; the HPLC data confirm the reduction of ASA concentration in the presence of magnesium stearate. With the other excipients the characteristic endotherms of the drug were always present and no or little degradation was observed with the accelerated stability tests. Therefore, the results with the DSC method are comparable and in good agreement with the results obtained with other methods.

Analytical tools for the analysis of β-carotene and its degradation products

PubMed Central

Stutz, H.; Bresgen, N.; Eckl, P. M.

2015-01-01

Abstract β-Carotene, the precursor of vitamin A, possesses pronounced radical scavenging properties. This has centered the attention on β-carotene dietary supplementation in healthcare as well as in the therapy of degenerative disorders and several cancer types. However, two intervention trials with β-carotene have revealed adverse effects on two proband groups, that is, cigarette smokers and asbestos-exposed workers. Beside other causative reasons, the detrimental effects observed have been related to the oxidation products of β-carotene. Their generation originates in the polyene structure of β-carotene that is beneficial for radical scavenging, but is also prone to oxidation. Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs). Due to their instability and hydrophobicity, the handling of standards and real samples containing β-carotene and related CPs requires preventive measures during specimen preparation, analyte extraction, and final analysis, to avoid artificial degradation and to preserve the initial analyte portfolio. This review critically discusses different preparation strategies of standards and treatment solutions, and also addresses their protection from oxidation. Additionally, in vitro oxidation strategies for the generation of oxidative model compounds are surveyed. Extraction methods are discussed for volatile and non-volatile CPs individually. Gas chromatography (GC), (ultra)high performance liquid chromatography (U)HPLC, and capillary electrochromatography (CEC) are reviewed as analytical tools for final analyte analysis. For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed. The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation. PMID:25867077

Insulation-resistance degradation kinetics of bulk BaTi1-ξAξO3-Δ and defect-chemical origin of acceptor-type(A) and doping-level(ξ) effect

NASA Astrophysics Data System (ADS)

Kwon, Hyung-Soon; Yoon, Seok-Hyun; Yoo, Han-Ill

2016-07-01

Dearth of the reproducible, consistent observations on insulation-resistance (IR) degradation kinetics of bulk dielectric BaTiO3 may be attributed to their conventional measurement method, two-probe potentiostatic, which would be by no means free from the electrode effect for a finite- dimension specimen in particular. We hereby measured the IR-degradation kinetics galvanostatically by using a series of inner probes on bulk BaTi1-ξAξO3-Δ (A = Al, Mn; ξ = 0.001, 0.003, 0.010) with their high-temperature (1000 °C) equilibrium ionic-defect-structure in air being frozen-in at 250 °C and compared with the kinetics as calculated on the basis of the electromigration of frozen-in oxygen vacancies ( cV o ) in association with the A-ionization or hole-trapping equilibria. It has turned out that the calculated depict sufficiently precisely all the as-observed kinetics as well as the effects of acceptor type(A) and doping level(ξ), thus, quantitatively establishing the correlation between the frozen-in ionic-defect-structure and IR-degradation kinetics with new insights into the degradation inner-workings: IR-degradation is triggered as soon as the oxygen vacancy concentration at the cathode reaches that corresponding to the insulator-to-semiconductor transition ( cV S / I ) and proceeds with the front of just-turned, n-type semiconducting region ( c V = cV S / I ) moving towards the anode at a fixed velocity. The healthy lifetime of the dielectric is, thus, essentially the time duration for the cathode to achieve cV S / I from cV o , and the final stage of degradation is approximated to be the length fraction χs of the semiconductor such that χs = cV o / cV S / I . A new suggestion is finally made to further suppress the IR degradation kinetics of the bulk dielectric BaTiO3.

Oxidative degradation of endotoxin by advanced oxidation process (O3/H2O2 & UV/H2O2).

PubMed

Oh, Byung-Taek; Seo, Young-Suk; Sudhakar, Dega; Choe, Ji-Hyun; Lee, Sang-Myeong; Park, Youn-Jong; Cho, Min

2014-08-30

The presence of endotoxin in water environments may pose a serious public health hazard. We investigated the effectiveness of advanced oxidative processes (AOP: O3/H2O2 and UV/H2O2) in the oxidative degradation of endotoxin. In addition, we measured the release of endotoxin from Escherichia coli following typical disinfection methods, such as chlorine, ozone alone and UV, and compared it with the use of AOPs. Finally, we tested the AOP-treated samples in their ability to induce tumor necrosis factor alpha (TNF-α) in mouse peritoneal macrophages. The production of hydroxyl radical in AOPs showed superior ability to degrade endotoxin in buffered solution, as well as water samples from Korean water treatment facilities, with the ozone/H2O2 being more efficient compared to UV/H2O2. In addition, the AOPs proved effective not only in eliminating E. coli in the samples, but also in endotoxin degradation, while the standard disinfection methods lead to the release of endotoxin following the bacteria destruction. Furthermore, in the experiments with macrophages, the AOPs-deactivated endotoxin lead to the smallest induction of TNF-α, which shows the loss of inflammation activity, compared to ozone treatment alone. In conclusion, these results suggest that AOPs offer an effective and mild method for endotoxin degradation in the water systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Degradation modeling of mid-power white-light LEDs by using Wiener process.

PubMed

Huang, Jianlin; Golubović, Dušan S; Koh, Sau; Yang, Daoguo; Li, Xiupeng; Fan, Xuejun; Zhang, G Q

2015-07-27

The IES standard TM-21-11 provides a guideline for lifetime prediction of LED devices. As it uses average normalized lumen maintenance data and performs non-linear regression for lifetime modeling, it cannot capture dynamic and random variation of the degradation process of LED devices. In addition, this method cannot capture the failure distribution, although it is much more relevant in reliability analysis. Furthermore, the TM-21-11 only considers lumen maintenance for lifetime prediction. Color shift, as another important performance characteristic of LED devices, may also render significant degradation during service life, even though the lumen maintenance has not reached the critical threshold. In this study, a modified Wiener process has been employed for the modeling of the degradation of LED devices. By using this method, dynamic and random variations, as well as the non-linear degradation behavior of LED devices, can be easily accounted for. With a mild assumption, the parameter estimation accuracy has been improved by including more information into the likelihood function while neglecting the dependency between the random variables. As a consequence, the mean time to failure (MTTF) has been obtained and shows comparable result with IES TM-21-11 predictions, indicating the feasibility of the proposed method. Finally, the cumulative failure distribution was presented corresponding to different combinations of lumen maintenance and color shift. The results demonstrate that a joint failure distribution of LED devices could be modeled by simply considering their lumen maintenance and color shift as two independent variables.

Lifetime Extension Report: Progress on the SAVY-4000 Lifetime Extension Program

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

Welch, Cynthia F.; Smith, Paul Herrick; Weis, Eric M.

The 3-year accelerated aging study of the SAVY-4000 O-ring shows very little evidence of significant degradation to samples subjected to aggressive elevated temperature and radiation conditions. Whole container thermal aging studies followed by helium leakage testing and compression set measurements were used to establish an estimate for a failure criterion for O-ring compression set of ≥65 %. The whole container aging studies further show that the air flow and efficiency functions of the filter do not degrade significantly after thermal aging. However, the degradation of the water-resistant function leads to water penetration failure after four months at 210°C, but doesmore » not cause failure after 10 months at 120°C (130°C is the maximum operating temperature for the PTFE membrane). The thermal aging data for O-ring compression set do not meet the assumptions of standard time-temperature superposition analysis for accelerated aging studies. Instead, the data suggest that multiple degradation mechanisms are operative, with a reversible mechanism operative at low aging temperatures and an irreversible mechanism dominating at high aging temperatures. To distinguish between these mechanisms, we have measured compression set after allowing the sample to physically relax, thereby minimizing the effect of the reversible mechanism. The resulting data were analyzed using two distinct mathematical methods to obtain a lifetime estimate based on chemical degradation alone. Both methods support a lifetime estimate of greater than 150 years at 80°C. Although the role of the reversible mechanism is not fully understood, it is clear that the contribution to the total compression set is small in comparison to that due to the chemical degradation mechanism. To better understand the chemical degradation mechanism, thermally aged O-ring samples have been characterized by Fourier Transform Infrared (FTIR), Electron Paramagnetic Resonance (EPR), Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC). These experiments detect no significant O-ring degradation below 80°C. Furthermore, durometer measurements indicate that there is no significant change in O-ring hardness at all aging conditions examined. Therefore, our current conservative lifetime estimate for the O-ring and the filter is 10 years at 80°C. In FY17, we will continue to probe the chemical degradation mechanism using oxygen consumption measurements under accelerated aging conditions to reveal temperatures at which oxidation occurs, along with any differences in oxidation rate at the low vs. high aging temperatures. We will also refine the failure criteria and finalize the radiation/thermal synergistic studies to determine a final design lifetime.« less

SAR Speckle Noise Reduction Using Wiener Filter

NASA Technical Reports Server (NTRS)

Joo, T. H.; Held, D. N.

1983-01-01

Synthetic aperture radar (SAR) images are degraded by speckle. A multiplicative speckle noise model for SAR images is presented. Using this model, a Wiener filter is derived by minimizing the mean-squared error using the known speckle statistics. Implementation of the Wiener filter is discussed and experimental results are presented. Finally, possible improvements to this method are explored.

Iterative Otsu's method for OCT improved delineation in the aorta wall

NASA Astrophysics Data System (ADS)

Alonso, Daniel; Real, Eusebio; Val-Bernal, José F.; Revuelta, José M.; Pontón, Alejandro; Calvo Díez, Marta; Mayorga, Marta; López-Higuera, José M.; Conde, Olga M.

2015-07-01

Degradation of human ascending thoracic aorta has been visualized with Optical Coherence Tomography (OCT). OCT images of the vessel wall exhibit structural degradation in the media layer of the artery, being this disorder the final trigger of the pathology. The degeneration in the vessel wall appears as low-reflectivity areas due to different optical properties of acidic polysaccharides and mucopolysaccharides in contrast with typical ordered structure of smooth muscle cells, elastin and collagen fibers. An OCT dimension indicator of wall degradation can be generated upon the spatial quantification of the extension of degraded areas in a similar way as conventional histopathology. This proposed OCT marker can offer in the future a real-time clinical perception of the vessel status to help cardiovascular surgeons in vessel repair interventions. However, the delineation of degraded areas on the B-scan image from OCT is sometimes difficult due to presence of speckle noise, variable signal to noise ratio (SNR) conditions on the measurement process, etc. Degraded areas can be delimited by basic thresholding techniques taking advantage of disorders evidences in B-scan images, but this delineation is not optimum in the aorta samples and requires complex additional processing stages. This work proposes an optimized delineation of degraded areas within the aorta wall, robust to noisy environments, based on the iterative application of Otsu's thresholding method. Results improve the delineation of wall anomalies compared with the simple application of the algorithm. Achievements could be also transferred to other clinical scenarios: carotid arteries, aorto-iliac or ilio-femoral sections, intracranial, etc.

Maximizing the concentrations of wheat grain fructans in bread by exploring strategies to prevent their yeast ( Saccharomyces cerevisiae )-mediated degradation.

PubMed

Verspreet, Joran; Hemdane, Sami; Dornez, Emmie; Cuyvers, Sven; Delcour, Jan A; Courtin, Christophe M

2013-02-13

The degradation of endogenous wheat grain fructans, oligosaccharides with possible health-promoting potential, during wheat whole meal bread making was investigated, and several strategies to prevent their degradation were evaluated. Up to 78.4 ± 5.2% of the fructans initially present in wheat whole meal were degraded during bread making by the action of yeast ( Saccharomyces cerevisiae ) invertase. The addition of sucrose to dough delayed fructan degradation but had no effect on final fructan concentrations. However, yeast growth conditions and yeast genotype did have a clear impact. A 3-fold reduction of fructan degradation could be achieved when the commercial bread yeast strain was replaced by yeast strains with lower sucrose degradation activity. Finally, fructan degradation during bread making could be prevented completely by the use of a yeast strain lacking invertase. These results show that the nutritional profile of bread can be enhanced through appropriate yeast technology.

Stereoselective Degradation and Molecular Ecological Mechanism of Chiral Pesticides Beta-Cypermethrin in Soils with Different pH Values.

PubMed

Yang, Zhong-Hua; Ji, Guo-Dong

2015-12-15

For decades, pesticides have been widely used for agricultural activities around the world, and the environmental problems caused by these compounds have raised widespread concern. However, the different enantioselective behaviors of chiral pesticide enantiomers are often ignored. Here, the selective degradation patterns and mechanisms of chiral pesticide enantiomers were successfully investigated for the first time in the soils of three cultivation areas with different pH values. Beta-cypermethrin was chosen as the target analyte. We found that the degradation rates of the four isomers of beta-cypermethrin were different. We used stepwise regression equations between degradation rates and functional genes to quantitatively study their relationships. Quantitative response analysis revealed that different isomers have different equations even under identical conditions. The results of path analysis showed that a single functional gene can make different direct and indirect contributions to the degradation of different isomers. Finally, the high-throughput technology was used to analysis the genome of the three tested soils and then compared the main microbial communities in them. We have successfully devised a method to investigate the molecular biological mechanisms of the selective degradation behavior of chiral compounds, thus enabling us to better understand these mechanisms.

Nonlinear Fatigue Damage Model Based on the Residual Strength Degradation Law

NASA Astrophysics Data System (ADS)

Yongyi, Gao; Zhixiao, Su

In this paper, a logarithmic expression to describe the residual strength degradation process is developed in order to fatigue test results for normalized carbon steel. The definition and expression of fatigue damage due to symmetrical stress with a constant amplitude are also given. The expression of fatigue damage can also explain the nonlinear properties of fatigue damage. Furthermore, the fatigue damage of structures under random stress is analyzed, and an iterative formula to describe the fatigue damage process is deduced. Finally, an approximate method for evaluating the fatigue life of structures under repeated random stress blocking is presented through various calculation examples.

Hydroxide based Benzyltrimethylammonium degradation: Quantification of rates and degradation technique development

DOE PAGES

Sturgeon, Matthew R.; Macomber, Clay S.; Engtrakul, Chaiwat; ...

2015-01-21

Anion exchange membranes (AEMs) are of interest as hydroxide conducting polymer electrolytes in electrochemical devices like fuel cells and electrolyzers. AEMs require hydroxide stable covalently tetherable cations to ensure required conductivity. Benzyltrimethylammonium (BTMA) has been the covalently tetherable cation that has been most often employed in anion exchange membranes because it is reasonably basic, compact (limited number of atoms per charge), and easily/cheaply synthesized. Several reports exist that have investigated hydroxide stability of BTMA under specific conditions, but consistency within these reports and comparisons between them have not yet been made. While the hydroxide stability of BTMA has been believedmore » to be a limitation for AEMs, this stability has not been thoroughly reported. In this paper, we have found that several methods reported have inherent flaws in their findings due to the difficulty of performing degradation experiments at high temperature and high pH. In order to address these shortcomings, we have developed a reliable, standardized method of determining cation degradation under conditions similar/relevant to those expected in electrochemical devices. The experimental method has been employed to determine BTMA stabilities at varying cation concentrations and elevated temperatures, and has resulted in improved experimental accuracy and reproducibility. Finally and most notably, these results have shown that BTMA is quite stable at 80°C (half-life of ~4 years), a significant increase in stability over what had been reported previously.« less

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. II. Comparison of simulations and experiments

NASA Astrophysics Data System (ADS)

Vahlman, H.; Haarahiltunen, A.; Kwapil, W.; Schön, J.; Inglese, A.; Savin, H.

2017-05-01

The presence of copper impurities is known to deteriorate the bulk minority carrier lifetime of silicon. In p-type silicon, the degradation occurs only under carrier injection (e.g., illumination), but the reason for this phenomenon called copper-related light-induced degradation (Cu-LID) has long remained uncertain. To clarify the physics of this problem, a mathematical model of Cu-LID was introduced in Paper I of this article. Within the model, kinetic precipitation simulations are interlinked with a Schottky junction model for electric behavior of metallic precipitates. As this approach enables simulating precipitation directly at the minority carrier lifetime level, the model is verified in this second part with a direct comparison to the corresponding degradation experiments and literature data. Convincing agreement is found with different doping and Cu concentrations as well as at increased temperature, and in the dark, both simulated degradation and measured degradation are very slow. In addition, modeled final lifetimes after illumination are very close to experimental final lifetimes, and a correlation with the final precipitate size is found. However, the model underestimates experimentally observed differences in the degradation rate at different illumination intensities. Nevertheless, the results of this work support the theory of Cu-LID as a precipitate formation process. Part of the results also imply that heterogeneous nucleation sites play a role during precipitate nucleation. The model reveals fundamental aspects of the physics of Cu-LID including how doping and heterogeneous nucleation site concentrations can considerably influence the final recombination activity.

Effect of food processing on degradation of hexachlorocyclohexane and its isomers in milk.

PubMed

Singh, Sujatha; Nelapati, Krishnaiah

2017-03-01

To study the effect of different food processing techniques on the degradation of organochlorine compounds (α, β, ɣ and δ hexachlorocyclohexane isomers (HCH)) residues in both natural and fortified samples of milk. Raw milk samples are collected from the local areas of Hyderabad, India. Naturally and fortified milk samples (HCH) were subjected to various food processing techniques, pasteurization (63ºC for ½ h), sterilization (121ºC for 15 min) and boiling for 5 min and analyzed by gas chromatography with electron capture detector using quick, easy, cheap, effective, rugged and safe method for multiresidue analysis of pesticides in milk with slight modification. The final mean residual concentration of pesticide in milk after heat processing and percentage of degradation were calculated with respective treatments. Heat treatments are highly effective on reduction of mean residual concentration of HCH in milk. In which Sterilization and boiling proved to be more effective in degradation of HCH isomers.

Degradation of Active Brilliant Red X-3B by a microwave discharge electrodeless lamp in the presence of activated carbon.

PubMed

Fu, Jie; Wen, Teng; Wang, Qing; Zhang, Xue-Wei; Zeng, Qing-Fu; An, Shu-Qing; Zhu, Hai-Liang

2010-06-01

Degradation of Active Brilliant Red X-3B (X-3B) in aqueous solution by a microwave discharge electrodeless lamp (MDEL) in the presence of activated carbon was investigated. The preliminary results proved this method could effectively degrade X-3B in aqueous solution. The removal percentages of colour and chemical oxygen demand were up to approximately 99% and 66%, respectively, at the conditions of 0.8 g/L dye concentration, 20 g/L activated carbon, pH 7.0 and 8 min microwave irradiation time. The degradation basically belonged to first-order reaction kinetics and its rate constant was 0.42 min(-1). No aromatic organics were detected in the final treated solution, indicating that the mineralization was relatively complete. By studying the change in solution properties, it could be concluded that MDEL-assisted oxidation was the dominant reaction mechanism. In addition, the influence of operational parameters and reuse of activated carbon were also discussed.

Measuring Road Network Vulnerability with Sensitivity Analysis

PubMed Central

Jun-qiang, Leng; Long-hai, Yang; Liu, Wei-yi; Zhao, Lin

2017-01-01

This paper focuses on the development of a method for road network vulnerability analysis, from the perspective of capacity degradation, which seeks to identify the critical infrastructures in the road network and the operational performance of the whole traffic system. This research involves defining the traffic utility index and modeling vulnerability of road segment, route, OD (Origin Destination) pair and road network. Meanwhile, sensitivity analysis method is utilized to calculate the change of traffic utility index due to capacity degradation. This method, compared to traditional traffic assignment, can improve calculation efficiency and make the application of vulnerability analysis to large actual road network possible. Finally, all the above models and calculation method is applied to actual road network evaluation to verify its efficiency and utility. This approach can be used as a decision-supporting tool for evaluating the performance of road network and identifying critical infrastructures in transportation planning and management, especially in the resource allocation for mitigation and recovery. PMID:28125706

Environmentally friendly chemical recycling of poly(bisphenol-A carbonate) through phase transfer-catalysed alkaline hydrolysis under microwave irradiation.

PubMed

Tsintzou, Georgia P; Antonakou, Eleni V; Achilias, Dimitris S

2012-11-30

The various and widespread uses of polycarbonate (PC) polymers require a meaningful and environmentally friendly disposal method. In this study, depolymerisation of polycarbonate with water in a microwave reactor is suggested as a recycling method. Hydrolysis was investigated in an alkaline (NaOH) solution using a phase-transfer catalyst. All of the experiments were carried out in a sealed microwave reactor, in which the reaction pressure, temperature and microwave power were continuously controlled and recorded. In the hydrolysis products, bisphenol-A monomer was obtained and identified by FTIR measurements. PC degradation higher than 80% can be obtained at 160°C after a microwave irradiation time of either 40 min or 10 min using either a 5 or 10% (w/v) NaOH solution, respectively. GPC, TGA and DSC measurements of the PC residues revealed that surface erosion is the degradation mechanism. First-order reaction kinetics were estimated by implementing a simple kinetic model. Finally, greater than 85% degradation was achieved when waste CDs were treated with the same method. The results confirm the importance of the microwave power technique as a promising recycling method for PC-based waste plastics, resulting in monomer recovery in addition to substantial energy savings. Copyright © 2012 Elsevier B.V. All rights reserved.

Progress of organic matter degradation and maturity of compost produced in a large-scale composting facility.

PubMed

Nakasaki, Kiyohiko; Marui, Taketoshi

2011-06-01

To monitor the progress of organic matter degradation in a large-scale composting facility, the percentage of organic matter degradation was determined by measuring CO(2) evolution during recomposting of compost samples withdrawn from the facility. The percentage of organic matter degradation was calculated as the ratio of the amount of CO(2) evolved from compost raw material to that evolved from each sample during recomposting in the laboratory composting apparatus. It was assumed that the difference in the cumulative emission of CO(2) between the compost raw material and a sample corresponds to the amount of CO( 2) evolved from the sample in the composting facility. Using this method, the changes in organic matter degradation during composting in practical large-scale composting facilities were estimated and it was found that the percentage of organic matter degradation increased more vigorously in the earlier stages than in the later stages of composting. The percentage of organic matter degradation finally reached 78 and 55% for the compost produced from garbage-animal manure mixture and distillery waste (shochu residue), respectively. It was thus ascertained that organic matter degradation progressed well in both composting facilities. Furthermore, by performing a plant growth assay, it was observed that the compost products of both the facilities did not inhibit seed germination and thus were useful in promoting plant growth.

Multi-PSF fusion in image restoration of range-gated systems

NASA Astrophysics Data System (ADS)

Wang, Canjin; Sun, Tao; Wang, Tingfeng; Miao, Xikui; Wang, Rui

2018-07-01

For the task of image restoration, an accurate estimation of degrading PSF/kernel is the premise of recovering a visually superior image. The imaging process of range-gated imaging system in atmosphere associates with lots of factors, such as back scattering, background radiation, diffraction limit and the vibration of the platform. On one hand, due to the difficulty of constructing models for all factors, the kernels from physical-model based methods are not strictly accurate and practical. On the other hand, there are few strong edges in images, which brings significant errors to most of image-feature-based methods. Since different methods focus on different formation factors of the kernel, their results often complement each other. Therefore, we propose an approach which combines physical model with image features. With an fusion strategy using GCRF (Gaussian Conditional Random Fields) framework, we get a final kernel which is closer to the actual one. Aiming at the problem that ground-truth image is difficult to obtain, we then propose a semi data-driven fusion method in which different data sets are used to train fusion parameters. Finally, a semi blind restoration strategy based on EM (Expectation Maximization) and RL (Richardson-Lucy) algorithm is proposed. Our methods not only models how the lasers transfer in the atmosphere and imaging in the ICCD (Intensified CCD) plane, but also quantifies other unknown degraded factors using image-based methods, revealing how multiple kernel elements interact with each other. The experimental results demonstrate that our method achieves better performance than state-of-the-art restoration approaches.

The synthesis of Cu/Fe/Fe3O4 catalyst through the aqueous solution ball milling method assisted by high-frequency electromagnetic field

NASA Astrophysics Data System (ADS)

Yingzhe, Zhang; Yuxing, He; Qingdong, Qin; Fuchun, Wang; Wankun, Wang; Yongmei, Luo

2018-06-01

In this paper, nano-magnetic Cu/Fe/Fe3O4 catalyst was prepared by a new aqueous solution ball milling method assisted by high-frequency electromagnetic field at room temperature. The products were characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and vibrating sample magnetometer (VSM). Microwave induced catalytic degradation of methylene blue (MB) was carried out in the presence of Cu/Fe/Fe3O4. The concentration of methylene blue was determined by UV-Vis spectrophotometry. The solid catalyst showed high catalytic activity of degrade MB and considerable saturation magnetization, lower remanence and coercivity. It indicate that the catalyst can be effectively separated for reuse by simply applying an external magnetic field and it can greatly promote their potential industrial application to eliminate organic pollutants from waste-water. Finally, we found that it is the non-thermal effect of microwave that activated the catalytic activity of Cu/Fe/Fe3O4 to degrade MB.

Blurred image restoration using knife-edge function and optimal window Wiener filtering.

PubMed

Wang, Min; Zhou, Shudao; Yan, Wei

2018-01-01

Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects.

Blurred image restoration using knife-edge function and optimal window Wiener filtering

PubMed Central

Zhou, Shudao; Yan, Wei

2018-01-01

Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects. PMID:29377950

Purification and crystallization of Bacillus subtilis NrnA, a novel enzyme involved in nanoRNA degradation

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

Nelersa, Claudiu M.; Schmier, Brad J.; Malhotra, Arun

2012-05-08

The final step in RNA degradation is the hydrolysis of RNA fragments five nucleotides or less in length (nanoRNA) to mononucleotides. In Escherichia coli this step is carried out by oligoribonuclease (Orn), a DEDD-family exoribonuclease that is conserved throughout eukaryotes. However, many bacteria lack Orn homologs, and an unrelated DHH-family phosphoesterase, NrnA, has recently been identified as one of the enzymes responsible for nanoRNA degradation in Bacillus subtilis. To understand its mechanism of action, B. subtilis NrnA was purified and crystallized at room temperature using the hanging-drop vapor-diffusion method with PEG 4000, PEG 3350 or PEG MME 2000 as precipitant.more » The crystals belonged to the primitive monoclinic space group P2{sub 1}, with unit-cell parameters a = 50.62, b = 121.3, c = 123.4 {angstrom}, {alpha} = 90, {beta} = 91.31, {gamma} = 90{sup o}.« less

Model-based restoration using light vein for range-gated imaging systems.

PubMed

Wang, Canjin; Sun, Tao; Wang, Tingfeng; Wang, Rui; Guo, Jin; Tian, Yuzhen

2016-09-10

The images captured by an airborne range-gated imaging system are degraded by many factors, such as light scattering, noise, defocus of the optical system, atmospheric disturbances, platform vibrations, and so on. The characteristics of low illumination, few details, and high noise make the state-of-the-art restoration method fail. In this paper, we present a restoration method especially for range-gated imaging systems. The degradation process is divided into two parts: the static part and the dynamic part. For the static part, we establish the physical model of the imaging system according to the laser transmission theory, and estimate the static point spread function (PSF). For the dynamic part, a so-called light vein feature extraction method is presented to estimate the fuzzy parameter of the atmospheric disturbance and platform movement, which make contributions to the dynamic PSF. Finally, combined with the static and dynamic PSF, an iterative updating framework is used to restore the image. Compared with the state-of-the-art methods, the proposed method can effectively suppress ringing artifacts and achieve better performance in a range-gated imaging system.

Development of a REBCO HTS magnet for Maglev - repeated bending tests of HTS pancake coils -

NASA Astrophysics Data System (ADS)

Sugino, Motohikoa; Mizuno, Katsutoshi; Tanaka, Minoru; Ogata, Masafumi

2018-01-01

In the past study, two manufacturing methods were developed that can manufacture pancake coils by using REBCO coated conductors. It was confirmed that the conductors have no electric degradation that caused by the manufacturing method. The durability evaluation tests of the pancake coils were conducted as the final evaluation of the coil manufacturing method in this study. The repeated bending deformation was applied to manufactured pancake coils in the tests. As the results of these tests, it was confirmed that the pancake coils that were manufactured by two methods had the durability for the repeated bending deformation and the coils maintained the appropriate mechanical performance and electric performance. We adopted the fusion bonding method as the coil manufacturing method of the HTS magnet Furthermore, using the prototype pancake coil that was manufactured by the fusion bonding method as a test sample, the repeated bending test under the exited condition was conducted. Thus it was confirmed that the coil manufactured by the fusion bonding method has no degradation of the electricity performance and the mechanical properties even if the repeated bending deformation was applied under the exited condition.

Reduction of matrix effects and improvement of sensitivity during determination of two chloridazon degradation products in aqueous matrices by using UPLC-ESI-MS/MS.

PubMed

Kowal, Sebastian; Balsaa, Peter; Werres, Friedrich; Schmidt, Torsten C

2012-06-01

The development and validation of a sensitive and reliable detection method for the determination of two polar degradation products, desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) in surface water, ground water and drinking water is presented. The method is based on direct large volume injection ultra-performance liquid chromatography electrospray tandem mass spectrometry. This simple but powerful analytical method for polar substances in the aquatic environment is usually hampered by varying matrix effects, depending on the nature of different water bodies. For the two examined degradation products, the matrix effects are particularly strong compared with other polar degradation products of pesticides. Therefore, matrix effects were studied thoroughly with the aim of minimising them and improving sensitivity during determination by postcolumn addition of ammonia solution as a modifier. An internal standard was used in order to compensate for remaining matrix effects. The calibration curve shows very good coefficients of correlation (0.9994 for DPC and 0.9999 for MDPC). Intraday precision values were lower than 5 % for DPC, 3 % for MDPC and the limits of detection were 10 ng/L for both substances. The method was successfully used in a national round robin test with a deviation between 3 and 8 % from target values. Finally, about 1,000 samples from different water bodies have been examined with this method in the Rhine and Ruhr region of North-Rhine-Westphalia (Germany) and in the European Union. Approximately 76 % of analysed samples contained measurable amounts of DPC at concentrations up to 8 μg/L while 53 % of the samples showed MDPC concentrations up to 2.3 μg/L.

Functional Degradable Polymers by Radical Ring-Opening Copolymerization of MDO and Vinyl Bromobutanoate: Synthesis, Degradability and Post-Polymerization Modification.

PubMed

Hedir, Guillaume G; Bell, Craig A; O'Reilly, Rachel K; Dove, Andrew P

2015-07-13

The synthesis of vinyl bromobutanoate (VBr), a new vinyl acetate monomer derivative obtained by the palladium-catalyzed vinyl exchange reaction between vinyl acetate (VAc) and 4-bromobutyric acid is reported. The homopolymerization of this new monomer using the RAFT/MADIX polymerization technique leads to the formation of novel well-defined and controlled polymers containing pendent bromine functional groups able to be modified via postpolymerization modification. Furthermore, the copolymerization of vinyl bromobutanoate with 2-methylene-1,3-dioxepane (MDO) was also performed to deliver a range of novel functional degradable copolymers, poly(MDO-co-VBr). The copolymer composition was shown to be able to be tuned to vary the amount of ester repeat units in the polymer backbone, and hence determine the degradability, while maintaining a control of the final copolymers' molar masses. The addition of functionalities via simple postpolymerization modifications such as azidation and the 1,3-dipolar cycloaddition of a PEG alkyne to an azide is also reported and proven by (1)H NMR spectroscopy, FTIR spectroscopy, and SEC analyses. These studies enable the formation of a novel class of hydrophilic functional degradable copolymers using versatile radical polymerization methods.

Scaling behavior of moisture-induced grain degradation in polycrystalline hybrid perovskite thin films

DOE PAGES

Wang, Qi; Chen, Bo; Liu, Ye; ...

2017-01-01

The stability of perovskite solar cells has shown a huge variation with respect to the film process and film morphology, while the underlining mechanism for the morphology-dependent degradation of the perovskite film has remained elusive. Herein, we report a scaling behavior of moisture-induced grain degradation in polycrystalline CH 3NH 3PbI 3 films. The degradation rates of CH 3NH 3PbI 3 films in moisture were shown to be sensitive to the grain sizes. The duration that was needed for different films to degrade by the same percent showed a linear relationship with the grain size, despite the fact that the filmsmore » were formed by five different deposition methods. This scaling behavior can be explained by the degradation along the in-plane direction, which is initiated at the grain boundary (GB). The GBs of CH 3NH 3PbI 3 films consist of an amorphous intergranular layer, which allows quick diffusion of moisture into the perovskite films. It was found that thermal annealing induced surface self-passivation plays a critical role in stabilizing the surfaces of thin films and single crystals by reducing the moisture-sensitive methylammonium ions at the surface. Finally, the determination of the scaling behavior of grain degradation highlights the importance of stabilizing the GBs to improve the stability of perovskite solar cells.« less

Inhibitory effects of polyphenol punicalagin on type-II collagen degradation in vitro and inflammation in vivo.

PubMed

Jean-Gilles, Dinorah; Li, Liya; Vaidyanathan, V G; King, Roberta; Cho, Bongsup; Worthen, David R; Chichester, Clinton O; Seeram, Navindra P

2013-09-25

Cartilage destruction is a crucial process in arthritis and is characterized by the degradation of cartilage proteins, proteoglycans, and type II collagen (CII), which are embedded within the extracellular matrix. While proteoglycan loss can be reversed, the degradation of CII is irreversible and has been correlated with an over-expression and over-activation of matrix metalloproteinases (MMPs). Among the various MMPs, the collagenase MMP-13 possesses the greatest catalytic activity for CII degradation. Here we show that the pomegranate-derived polyphenols, punicalagin (PA) and ellagic acid (EA), inhibit MMP-13-mediated degradation of CII in vitro. Surface plasmon resonance studies and molecular docking simulations suggested multiple binding interactions of PA and EA with CII. The effects of PA on bovine cartilage degradation (stimulated with IL-1β) were investigated by assaying proteoglycan and CII release into cartilage culture media. PA inhibited the degradation of both proteins in a concentration-dependent manner. Finally, the anti-inflammatory effects of PA (daily IP delivery at 10 and 50mg/kg for 14days) were tested in an adjuvant-induced arthritis rat model. Disease development was assessed by daily measurements of body weight and paw volume (using the water displacement method). PA had no effect on disease development at the lower dose but inhibited paw volume (P<0.05) at the higher dose. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Scaling behavior of moisture-induced grain degradation in polycrystalline hybrid perovskite thin films

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

Wang, Qi; Chen, Bo; Liu, Ye

The stability of perovskite solar cells has shown a huge variation with respect to the film process and film morphology, while the underlining mechanism for the morphology-dependent degradation of the perovskite film has remained elusive. Herein, we report a scaling behavior of moisture-induced grain degradation in polycrystalline CH 3NH 3PbI 3 films. The degradation rates of CH 3NH 3PbI 3 films in moisture were shown to be sensitive to the grain sizes. The duration that was needed for different films to degrade by the same percent showed a linear relationship with the grain size, despite the fact that the filmsmore » were formed by five different deposition methods. This scaling behavior can be explained by the degradation along the in-plane direction, which is initiated at the grain boundary (GB). The GBs of CH 3NH 3PbI 3 films consist of an amorphous intergranular layer, which allows quick diffusion of moisture into the perovskite films. It was found that thermal annealing induced surface self-passivation plays a critical role in stabilizing the surfaces of thin films and single crystals by reducing the moisture-sensitive methylammonium ions at the surface. Finally, the determination of the scaling behavior of grain degradation highlights the importance of stabilizing the GBs to improve the stability of perovskite solar cells.« less

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

Sun, Rongyu; Zhao, Changyin; Zhang, Xiaoxiang, E-mail: cyzhao@pmo.ac.cn

The data reduction method for optical space debris observations has many similarities with the one adopted for surveying near-Earth objects; however, due to several specific issues, the image degradation is particularly critical, which makes it difficult to obtain precise astrometry. An automatic image reconstruction method was developed to improve the astrometry precision for space debris, based on the mathematical morphology operator. Variable structural elements along multiple directions are adopted for image transformation, and then all the resultant images are stacked to obtain a final result. To investigate its efficiency, trial observations are made with Global Positioning System satellites and themore » astrometry accuracy improvement is obtained by comparison with the reference positions. The results of our experiments indicate that the influence of degradation in astrometric CCD images is reduced, and the position accuracy of both objects and stellar stars is improved distinctly. Our technique will contribute significantly to optical data reduction and high-order precision astrometry for space debris.« less

A novel adaptive switching function on fault tolerable sliding mode control for uncertain stochastic systems.

PubMed

Zahiripour, Seyed Ali; Jalali, Ali Akbar

2014-09-01

A novel switching function based on an optimization strategy for the sliding mode control (SMC) method has been provided for uncertain stochastic systems subject to actuator degradation such that the closed-loop system is globally asymptotically stable with probability one. In the previous researches the focus on sliding surface has been on proportional or proportional-integral function of states. In this research, from a degree of freedom that depends on designer choice is used to meet certain objectives. In the design of the switching function, there is a parameter which the designer can regulate for specified objectives. A sliding-mode controller is synthesized to ensure the reachability of the specified switching surface, despite actuator degradation and uncertainties. Finally, the simulation results demonstrate the effectiveness of the proposed method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Scattering Removal for Finger-Vein Image Restoration

PubMed Central

Yang, Jinfeng; Zhang, Ben; Shi, Yihua

2012-01-01

Finger-vein recognition has received increased attention recently. However, the finger-vein images are always captured in poor quality. This certainly makes finger-vein feature representation unreliable, and further impairs the accuracy of finger-vein recognition. In this paper, we first give an analysis of the intrinsic factors causing finger-vein image degradation, and then propose a simple but effective image restoration method based on scattering removal. To give a proper description of finger-vein image degradation, a biological optical model (BOM) specific to finger-vein imaging is proposed according to the principle of light propagation in biological tissues. Based on BOM, the light scattering component is sensibly estimated and properly removed for finger-vein image restoration. Finally, experimental results demonstrate that the proposed method is powerful in enhancing the finger-vein image contrast and in improving the finger-vein image matching accuracy. PMID:22737028

Pre-formulation studies of resveratrol

PubMed Central

Robinson, Keila; Mock, Charlotta; Liang, Dong

2015-01-01

Context Resveratrol, a natural compound found in grapes, has potential chemotherapy effects but very low oral bioavailability in humans. Objective To evaluate the solubility, pH stability profile, plasma protein binding (PPB) and stability in plasma for resveratrol. Methods Solubility of resveratrol was measured in 10 common solvents at 25 °C using HPLC. The solution state pH stability of resveratrol was assessed in various United States Pharmacopeia buffers ranging from pH 2 to 10 for 24 h at 37 °C. Samples were analyzed up to 24 h. Human PPB was determined using ultracentrifugation technique. Standard solutions of drug were spiked to blank human plasma to yield final concentrations of 5, 12.5 or 25 µg/mL for determination. Finally, stability of resveratrol in human and rat plasma was also assessed at 37 °C. Aliquots of blank plasma were spiked with a standard drug concentration to yield final plasma concentration of 50 µg/mL. Samples were analyzed for resveratrol concentration up to 96 h. Results Resveratrol has wide solubility ranging from 0.05 mg/mL in water to 374 mg/mL in polyethylene glycol 400 (PEG-400). Resveratrol is relatively stable above pH 6 and has maximum degradation at pH 9. The mean PPB of resveratrol is 98.3%. Resveratrol degrades in human and rat plasma in a first-order process with mean half lives of 54 and 25 h, respectively. Conclusion Resveratrol is more soluble in alcohol and PEG-400 and stable in acidic pH. It binds highly to plasma proteins and degrades slower in human then rat plasma. PMID:25224342

76 FR 11965 - Peroxyacetic Acid; Amendment to an Exemption From the Requirement of a Tolerance

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-04

... of PAA PAA degrades rapidly to AA and HP, and HP further degrades to water and oxygen; therefore, the final degradation products of PAA are AA, water, and oxygen. As stated in Unit II., section 408(a)(3... concluded that, since HP itself degrades rapidly into oxygen and water, residues of a solution that contains...

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.

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

NASA Astrophysics Data System (ADS)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

Polymeric Nanofibers in Tissue Engineering

PubMed Central

Dahlin, Rebecca L.; Kasper, F. Kurtis

2011-01-01

Polymeric nanofibers can be produced using methods such as electrospinning, phase separation, and self-assembly, and the fiber composition, diameter, alignment, degradation, and mechanical properties can be tailored to the intended application. Nanofibers possess unique advantages for tissue engineering. The small diameter closely matches that of extracellular matrix fibers, and the relatively large surface area is beneficial for cell attachment and bioactive factor loading. This review will update the reader on the aspects of nanofiber fabrication and characterization important to tissue engineering, including control of porous structure, cell infiltration, and fiber degradation. Bioactive factor loading will be discussed with specific relevance to tissue engineering. Finally, applications of polymeric nanofibers in the fields of bone, cartilage, ligament and tendon, cardiovascular, and neural tissue engineering will be reviewed. PMID:21699434

Prediction and measurement results of radiation damage to CMOS devices on board spacecraft

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Danchenko, V.; Cliff, R. A.; Sing, M.; Brucker, G. J.; Ohanian, R. S.

1977-01-01

Final results from the CMOS Radiation Effects Measurement (CREM) experiment flown on Explorer 55 are presented and discussed, based on about 15 months of observations and measurements. Conclusions are given relating to long-range annealing, effects of operating temperature on semiconductor performance in space, biased and unbiased P-MOS device degradation, unbiased n-channel device performance, changes in device transconductance, and the difference in ionization efficiency between Co-60 gamma rays and 1-Mev Van de Graaff electrons. The performance of devices in a heavily shielded electronic subsystem box within the spacecraft is evaluated and compared. Environment models and computational methods and their impact on device-degradation estimates are being reviewed to determine whether they permit cost-effective design of spacecraft.

[Preparation of Coated CMC-Fe0 Using Rheological Phase Reaction Method and Research on Degradation of TCE in Water].

PubMed

Fan, Wen-jing; Cheng, Yue; Yu, Shu-zhen; Fan, Xiao-feng

2015-06-01

The coated nanoscale zero-valent iron (coated CMC-Fe0) was synthesized with cheap and environment friendly CMC as the coating agent using rheological phase reaction. The sample was characterized by means of XRD, SEM, TEM and N2 adsorption-stripping and used to study reductive dechlorination of TCE. The experimental results indicated that the removal rate of TCE was about 100% when the CMC-Fe0 dosage was 6 g x L(-1), the initial TCE concentration was 5 mg x L(-1) and the reaction time was 40 h. The TCE degradation reaction of coated CMC-Fe0 followed a pseudo-first-order kinetic model. Finally, the product could be simply recovered.

Acetogenic microbial degradation of vinyl chloride

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

2000-01-01

Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C- acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries, respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and humic acids- reducing conditions.Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C-acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and humic acids-reducing conditions.

Oxidative degradation of the antibiotic oxytetracycline by Cu@Fe3O4 core-shell nanoparticles.

PubMed

Pham, Van Luan; Kim, Do-Gun; Ko, Seok-Oh

2018-08-01

A core-shell nanostructure composed of zero-valent Cu (core) and Fe 3 O 4 (shell) (Cu@Fe 3 O 4 ) was prepared by a simple reduction method and was evaluated for the degradation of oxytetracycline (OTC), an antibiotic. The Cu core and the Fe 3 O 4 shell were verified by X-ray diffractometry (XRD) and transmission electron microscopy. The optimal molar ratio of [Cu]/[Fe] (1/1) in Cu@Fe 3 O 4 created an outstanding synergic effect, leading to >99% OTC degradation as well as H 2 O 2 decomposition within 10min at the reaction conditions of 1g/L Cu@Fe 3 O 4 , 20mg/L OTC, 20mM H 2 O 2 , and pH3.0 (and even at pH9.0). The OTC degradation rate by Cu@Fe 3 O 4 was higher than obtained using single nanoparticle of Cu or Fe 3 O 4 . The results of the study using radical scavengers showed that OH is the major reactive oxygen species contributing to the OTC degradation. Finally, good stability, reusability, and magnetic separation were obtained with approximately 97% OTC degradation and no notable change in XRD patterns after the Cu@Fe 3 O 4 catalyst was reused five times. These results demonstrate that Cu@Fe 3 O 4 is a novel prospective candidate for the pharmaceutical and personal care products degradation in the aqueous phase. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced degradation of 4-nitrophenol by microwave assisted Fe/EDTA process.

PubMed

Liu, Bo; Li, Song; Zhao, Yongjun; Wu, Wenfei; Zhang, Xuxiang; Gu, Xueyuan; Li, Ruihua; Yang, Shaogui

2010-04-15

A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD(5)/COD(Cr) of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods. Crown Copyright 2009. Published by Elsevier B.V. All rights reserved.

A novel approach on accelerated ageing towards reliability optimization of high concentration photovoltaic cells

NASA Astrophysics Data System (ADS)

Tsanakas, John A.; Jaffre, Damien; Sicre, Mathieu; Elouamari, Rachid; Vossier, Alexis; de Salins, Jean-Edouard; Bechou, Laurent; Levrier, Bruno; Perona, Arnaud; Dollet, Alain

2014-09-01

This paper presents a preliminary study upon a novel approach proposed for highly accelerated ageing and reliability optimization of high concentrating photovoltaic (HCPV) cells and assemblies. The intended approach aims to overcome several limitations of some current accelerated ageing tests (AAT) adopted up today, proposing the use of an alternative experimental set-up for performing faster and more realistic thermal cycles, under real sun, without the involvement of environmental chamber. The study also includes specific characterization techniques, before and after each AAT sequence, which respectively provide the initial and final diagnosis on the condition of the tested sample. The acquired data from these diagnostic/characterization methods are then used as indices to determine both quantitatively and qualitatively the severity of degradation and, thus, the ageing level for each tested HCPV assembly or cell sample. Ultimate goal of such "initial diagnosis - AAT - final diagnosis" sequences is to provide the basis for a future work on the reliability analysis of the main degradation mechanisms and confident prediction of failure propagation in HCPV cells, by means of acceleration factor (AF) and mean-time-to-failure (MTTF) estimations.

Degradation of Polymeric Brominated Flame Retardants: Development of an Analytical Approach Using PolyFR and UV Irradiation.

PubMed

Koch, Christoph; Dundua, Alexander; Aragon-Gomez, Jackelyn; Nachev, Milen; Stephan, Susanne; Willach, Sarah; Ulbricht, Mathias; Schmitz, Oliver J; Schmidt, Torsten C; Sures, Bernd

2016-12-06

Many well-established methods for studying the degradation of brominated flame retardants are not useful when working with polymeric and water insoluble species. An example for this specific class of flame retardants is PolyFR (polymeric flame retardant; CAS No 1195978-93-8), which is used as a substituent for hexabromocyclododecane. Although it has been on the market for two years now, almost no information is available about its long time behavior in the environment. Within this study, we focus on how to determine a possible degradation of both pure PolyFR as well as PolyFR in the final insulation product, expanded polystyrene foam. Therefore, we chose UV radiation followed by analyses of the total bromine content at different time points via ICP-MS and identified possible degradation products such as 2,4,6-tribromophenol through LC-MS. These results were then linked with measurements of the adsorbable organically bound bromine and total organic carbon in order to estimate their concentrations. With respect to the obtained 1 H NMR, GPC, and contact angle results, the possibility for further degradation was discussed, as UV irradiation can influence the decomposition of molecules in combination with other environmental factors like biodegradation.

Degradation spectra and ionization yields of electrons in gases

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

Inokuti, M.; Douthat, D.A.; Rau, A.R.P.

1975-01-01

Progress in the microscopic theory of electron degradation in gases by Platzman, Fano, and co-workers is outlined. The theory consists of (1) the cataloging of all major inelastic-collision cross sections for electrons (including secondary-electron energy distribution in a single ionizing collision) and (2) the evaluation of cumulative consequences of individual electron collisions for the electrons themselves as well as for target molecules. For assessing the data consistency and reliability and extrapolating the data to the unexplored ranges of variables (such as electron energy), a series of plots devised by Platzman are very powerful. Electron degradation spectra were obtained through numericalmore » solution of the Spencer--Fano equation for all electron energies down to the first ionization thresholds for a few examples such as He and Ne. The systematics of the solutions resulted in the recognition of approximate scaling properties of the degradation spectra for different initial electron energies and pointed to new methods of more efficient treatment. Systematics of the ionization yields and their energy dependence on the initial electron energy were also recognized. Finally, the Spencer--Fano equation for the degradation spectra and the Fowler equation for the ionization and other yields are tightly linked with each other by a set of variational principles. (52 references, 7 figures) (DLC)« less

The impact of calcium carbonate as pore forming agent and drug entrapment method towards drug dissolution mechanism of amoxicillin trihydrate encapsulated by chitosan-methyl cellulose semi-IPN hydrogel for floating drug delivery system

NASA Astrophysics Data System (ADS)

Dewantara, Fauzi; Budianto, Emil

2018-04-01

Chitosan-methyl cellulose semi-IPN hydrogel is used as floating drug delivery system, and calcium carbonate also added as pore forming agent. The hydrogel network arranged by not only using biopolymer chitosan and methyl cellulose, but also the crosslink agent that is glutaraldehyde. Amoxicillin trihydrate entrapped into the polymer network with two different method, in situ loading and post loading. Furthermore both method has been tested for drug entrapment efficiency along with drug dissolution test, and the result for drug entrapment efficiency is in situ loading method has highest value of 100%, compared to post loading method which has value only 71%. Moreover, at the final time of drug dissolution test shows in situ loading method has value of 96% for total accumulative of drug dissolution, meanwhile post loading method has 72%. The value of drug dissolution test from both method is used for analyzing drug dissolution mechanism of amoxicillin trihydrate from hydrogel network with four mathematical drug mechanism models as parameter. The polymer network encounter destructive degradation causes by acid solution which used as dissolution medium, and the level of degradation is observed with optical microscope. However the result shows that degradation of the polymer network doesn't affect drug dissolution mechanism directly. Although the pore forming agent causes the pore inside the hydrogel network create interconnection and it was quite influential to drug dissolution mechanism. Interconnected pore is observed with Scanning Electron Microscope (SEM) and shows that the amount and area of interconnected pore inside the hydrogel network is increasing as drug dissolution goes on.

Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

NASA Astrophysics Data System (ADS)

Cha, Kyoung Je; Kim, Taewan; Jea Park, Sung; Kim, Dong Sung

2014-11-01

Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.

Extrinsic Cognitive Load Impairs Spoken Word Recognition in High- and Low-Predictability Sentences.

PubMed

Hunter, Cynthia R; Pisoni, David B

Listening effort (LE) induced by speech degradation reduces performance on concurrent cognitive tasks. However, a converse effect of extrinsic cognitive load on recognition of spoken words in sentences has not been shown. The aims of the present study were to (a) examine the impact of extrinsic cognitive load on spoken word recognition in a sentence recognition task and (b) determine whether cognitive load and/or LE needed to understand spectrally degraded speech would differentially affect word recognition in high- and low-predictability sentences. Downstream effects of speech degradation and sentence predictability on the cognitive load task were also examined. One hundred twenty young adults identified sentence-final spoken words in high- and low-predictability Speech Perception in Noise sentences. Cognitive load consisted of a preload of short (low-load) or long (high-load) sequences of digits, presented visually before each spoken sentence and reported either before or after identification of the sentence-final word. LE was varied by spectrally degrading sentences with four-, six-, or eight-channel noise vocoding. Level of spectral degradation and order of report (digits first or words first) were between-participants variables. Effects of cognitive load, sentence predictability, and speech degradation on accuracy of sentence-final word identification as well as recall of preload digit sequences were examined. In addition to anticipated main effects of sentence predictability and spectral degradation on word recognition, we found an effect of cognitive load, such that words were identified more accurately under low load than high load. However, load differentially affected word identification in high- and low-predictability sentences depending on the level of sentence degradation. Under severe spectral degradation (four-channel vocoding), the effect of cognitive load on word identification was present for high-predictability sentences but not for low-predictability sentences. Under mild spectral degradation (eight-channel vocoding), the effect of load was present for low-predictability sentences but not for high-predictability sentences. There were also reliable downstream effects of speech degradation and sentence predictability on recall of the preload digit sequences. Long digit sequences were more easily recalled following spoken sentences that were less spectrally degraded. When digits were reported after identification of sentence-final words, short digit sequences were recalled more accurately when the spoken sentences were predictable. Extrinsic cognitive load can impair recognition of spectrally degraded spoken words in a sentence recognition task. Cognitive load affected word identification in both high- and low-predictability sentences, suggesting that load may impact both context use and lower-level perceptual processes. Consistent with prior work, LE also had downstream effects on memory for visual digit sequences. Results support the proposal that extrinsic cognitive load and LE induced by signal degradation both draw on a central, limited pool of cognitive resources that is used to recognize spoken words in sentences under adverse listening conditions.

Methodology for the assessment of the impacts of climate change on land degradation at multiple scales: Use of high resolution satellite imagery, modelling, and ground measurements for the assessment in Ethiopia

NASA Astrophysics Data System (ADS)

Ahmed, Oumer

In this study, a new multi-scalar methodology for assessing land degradation response to climate change is presented by analyzing 22 years of both climatic data and satellite observations, together with future projections from modelling, for Ethiopia. A comprehensive analysis of the impacts of climate change on land degradation was performed as evidenced from the integration of a host of land degradation indicators, namely: normalized difference vegetation Index (NDVI), net primary productivity (NPP), crop yield, biomass, length of growing period (LGP), rainfall use efficiency (RUE), energy use efficiency (EUE) and aridity index (AI). The results from the national level assessment indicate that over the period of 1984-2006, NPP decreased overall. Degrading areas occupy 30% of the country and suffer an average loss of NPP 10.3 kg C ha-1 y-1. The crop yield prediction results indicate a wide range of outcomes is to be expected for the country, due to the heterogeneity of the agro-climatic resources as well as of projected climate change. The results of the sub-national level assessment show that about 29% of the Awash watershed is degrading, and these degrading areas experience an average loss of NPP 4.6 kg C ha-1 y-1. Further, about 33.8% of the degrading area in the watershed is associated with bare land and 25% with agricultural land. Finally, since remotely sensed estimates are frequently used to assess land degradation at multiple scales, scale transfer methods are evaluated in this study to provide a tool to rank both upscaling and downscaling procedures.

The role of microscaffold properties in controlling the collagen assembly in 3D dermis equivalent using modular tissue engineering.

PubMed

Imparato, Giorgia; Urciuolo, Francesco; Casale, Costantino; Netti, Paolo A

2013-10-01

The realization of thick and viable tissues equivalents in vitro is one of the mayor challenges in tissue engineering, in particular for their potential use in tissue-on-chip technology. In the present study we succeeded in creating 3D viable dermis equivalent tissue, via a bottom-up method, and proved that the final properties, in terms of collagen assembly and organization of the 3D tissue, are tunable and controllable by micro-scaffold properties and degradation rate. Gelatin porous microscaffolds with controlled stiffness and degradation rate were realized by changing the crosslinking density through different concentrations of glyceraldehyde. Results showed that by modulating the crosslinking density of the gelatin microscaffolds it is possible to guide the process of collagen deposition and assembly within the extracellular space and match the processes of scaffold degradation, cell traction and tissue maturation to obtain firmer collagen network able to withstand the effect of contraction. © 2013 Published by Elsevier Ltd.

An interpenetrating HA/G/CS biomimic hydrogel via Diels-Alder click chemistry for cartilage tissue engineering.

PubMed

Yu, Feng; Cao, Xiaodong; Zeng, Lei; Zhang, Qing; Chen, Xiaofeng

2013-08-14

In order to mimic the natural cartilage extracellular matrix, a novel biological degradable interpenetrating network hydrogel was synthesized from the gelatin (G), hyaluronic acid (HA) and chondroitin sulfate (CS) by Diels-Alder "click" chemistry. HA was modified with furylamine and G was modified with furancarboxylic acid respectively. (1)H NMR spectra and elemental analysis showed that the substitution degrees of HA-furan and G-furan were 71.5% and 44.5%. Then the hydrogels were finally synthesized by cross-linking furan-modified HA and G derivatives with dimaleimide poly(ethylene glycol) (MAL-PEG-MAL). The mechanical and degradation properties of the hydrogels could be tuned simply through varying the molar ratio between furan and maleimide. Rheological, mechanical and degradation studies demonstrated that the Diels-Alder "click" chemistry is an efficient method for preparing high performance biological interpenetrating hydrogels. This biomimic hydrogel with improved mechanical properties could have great potential applications in cartilage tissue engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biodegradation Behaviour of Thermoplastic Starch Films Derived from Tacca leontopetaloides Starch under Controlled Composting Condition

NASA Astrophysics Data System (ADS)

Amin, A. M. Mohd; Sauid, S. Mohd; Hamid, K. H. Ku; Musa, M.

2018-05-01

The biodegradation study of thermoplastic starch (TPS) films derived from Tacca leontopetaloides starch; namely TPS/GLY, TPS/ACE and TPS/BCHR were investigated under controlled composting conditions. A manual set-up test rig in laboratory scale was built according to ISO 14855-1: 2012. The biodegradation percentage was determined by measuring the amount of CO2 evolved using titration method and validated by automatic system (Arduino UNO System) that detected the CO2 evolved. After 45 days under controlled composting condition, results indicated that TPS/GLY degraded the fastest, followed by TPS/BCHR and the TPS/ACE had the slowest degradation. The biodegradation process of TPS/GLY, TPS/ACE and TPS/BCHR also exhibited two stages with different degradation speeds. From these results, it indicated that chemical modification of the TPS films by adding acetic acid and rice husk bio-char to the thermoplastic starch can have a major impact on the biodegradation rate and final biodegradation percentage.

Evaluation of GaAs low noise and power MMIC technologies to neutron, ionizing dose and dose rate effects

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

Derewonko, H.; Bosella, A.; Pataut, G.

1996-06-01

An evaluation program of Thomson CSF-TCS GaAs low noise and power MMIC technologies to 1 MeV equivalent neutron fluence levels, up to 1 {times} 10{sup 15} n/cm{sup 2}, ionizing 1.17--1.33 MeV CO{sup 60} dose levels in excess of 200 Mrad(GaAs) and dose rate levels reaching 1.89 {times} 10{sup 11} rad(GaAs)/s is presented in terms of proper components and parameter choices, DC/RF electrical measurements and test methods under irradiation. Experimental results are explained together with drift analyses of electrical parameters that have determined threshold limits of component degradations. Modelling the effects of radiation on GaAs components relies on degradation analysis ofmore » active layer which appears to be the most sensitive factor. MMICs degradation under neutron fluence was simulated from irradiated FET data. Finally, based on sensitivity of technological parameters, rad-hard design including material, technology and MMIC design enhancement is discussed.« less

Degradation of Energetic Compounds using Zero-Valent Iron (ZVI)

DTIC Science & Technology

2012-03-01

control number. 1. REPORT DATE MAR 2012 2. REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4 . TITLE AND SUBTITLE Degradation of Energetic...the column effluents were collected and passed through a 0.22- µm cellulose membrane filter (Millipore, Bedford, MA) for HPLC analysis. Degradation ...FINAL REPORT Degradation of Energetic Compounds Using Zero-Valent Iron (ZVI) ESTCP Project WP-200524 MARCH 2012 Byung J. Kim U.S

Post-processing through linear regression

NASA Astrophysics Data System (ADS)

van Schaeybroeck, B.; Vannitsem, S.

2011-03-01

Various post-processing techniques are compared for both deterministic and ensemble forecasts, all based on linear regression between forecast data and observations. In order to evaluate the quality of the regression methods, three criteria are proposed, related to the effective correction of forecast error, the optimal variability of the corrected forecast and multicollinearity. The regression schemes under consideration include the ordinary least-square (OLS) method, a new time-dependent Tikhonov regularization (TDTR) method, the total least-square method, a new geometric-mean regression (GM), a recently introduced error-in-variables (EVMOS) method and, finally, a "best member" OLS method. The advantages and drawbacks of each method are clarified. These techniques are applied in the context of the 63 Lorenz system, whose model version is affected by both initial condition and model errors. For short forecast lead times, the number and choice of predictors plays an important role. Contrarily to the other techniques, GM degrades when the number of predictors increases. At intermediate lead times, linear regression is unable to provide corrections to the forecast and can sometimes degrade the performance (GM and the best member OLS with noise). At long lead times the regression schemes (EVMOS, TDTR) which yield the correct variability and the largest correlation between ensemble error and spread, should be preferred.

Monitoring cell culture media degradation using surface enhanced Raman scattering (SERS) spectroscopy.

PubMed

Calvet, Amandine; Ryder, Alan G

2014-08-20

The quality of the cell culture media used in biopharmaceutical manufacturing is a crucial factor affecting bioprocess performance and the quality of the final product. Due to their complex composition these media are inherently unstable, and significant compositional variations can occur particularly when in the prepared liquid state. For example photo-degradation of cell culture media can have adverse effects on cell viability and thus process performance. There is therefore, from quality control, quality assurance and process management view points, an urgent demand for the development of rapid and inexpensive tools for the stability monitoring of these complex mixtures. Spectroscopic methods, based on fluorescence or Raman measurements, have now become viable alternatives to more time-consuming and expensive (on a unit analysis cost) chromatographic and/or mass spectrometry based methods for routine analysis of media. Here we demonstrate the application of surface enhanced Raman scattering (SERS) spectroscopy for the simple, fast, analysis of cell culture media degradation. Once stringent reproducibility controls are implemented, chemometric data analysis methods can then be used to rapidly monitor the compositional changes in chemically defined media. SERS shows clearly that even when media are stored at low temperature (2-8°C) and in the dark, significant chemical changes occur, particularly with regard to cysteine/cystine concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

Reduced kernel recursive least squares algorithm for aero-engine degradation prediction

NASA Astrophysics Data System (ADS)

Zhou, Haowen; Huang, Jinquan; Lu, Feng

2017-10-01

Kernel adaptive filters (KAFs) generate a linear growing radial basis function (RBF) network with the number of training samples, thereby lacking sparseness. To deal with this drawback, traditional sparsification techniques select a subset of original training data based on a certain criterion to train the network and discard the redundant data directly. Although these methods curb the growth of the network effectively, it should be noted that information conveyed by these redundant samples is omitted, which may lead to accuracy degradation. In this paper, we present a novel online sparsification method which requires much less training time without sacrificing the accuracy performance. Specifically, a reduced kernel recursive least squares (RKRLS) algorithm is developed based on the reduced technique and the linear independency. Unlike conventional methods, our novel methodology employs these redundant data to update the coefficients of the existing network. Due to the effective utilization of the redundant data, the novel algorithm achieves a better accuracy performance, although the network size is significantly reduced. Experiments on time series prediction and online regression demonstrate that RKRLS algorithm requires much less computational consumption and maintains the satisfactory accuracy performance. Finally, we propose an enhanced multi-sensor prognostic model based on RKRLS and Hidden Markov Model (HMM) for remaining useful life (RUL) estimation. A case study in a turbofan degradation dataset is performed to evaluate the performance of the novel prognostic approach.

Spectrum recovery method based on sparse representation for segmented multi-Gaussian model

NASA Astrophysics Data System (ADS)

Teng, Yidan; Zhang, Ye; Ti, Chunli; Su, Nan

2016-09-01

Hyperspectral images can realize crackajack features discriminability for supplying diagnostic characteristics with high spectral resolution. However, various degradations may generate negative influence on the spectral information, including water absorption, bands-continuous noise. On the other hand, the huge data volume and strong redundancy among spectrums produced intense demand on compressing HSIs in spectral dimension, which also leads to the loss of spectral information. The reconstruction of spectral diagnostic characteristics has irreplaceable significance for the subsequent application of HSIs. This paper introduces a spectrum restoration method for HSIs making use of segmented multi-Gaussian model (SMGM) and sparse representation. A SMGM is established to indicating the unsymmetrical spectral absorption and reflection characteristics, meanwhile, its rationality and sparse property are discussed. With the application of compressed sensing (CS) theory, we implement sparse representation to the SMGM. Then, the degraded and compressed HSIs can be reconstructed utilizing the uninjured or key bands. Finally, we take low rank matrix recovery (LRMR) algorithm for post processing to restore the spatial details. The proposed method was tested on the spectral data captured on the ground with artificial water absorption condition and an AVIRIS-HSI data set. The experimental results in terms of qualitative and quantitative assessments demonstrate that the effectiveness on recovering the spectral information from both degradations and loss compression. The spectral diagnostic characteristics and the spatial geometry feature are well preserved.

Facile Fabrication of BiOI/BiOCl Immobilized Films with Improved Visible Light Photocatalytic Performance

NASA Astrophysics Data System (ADS)

Zhong, Yingxian; Liu, Yuehua; Wu, Shuang; Zhu, Yi; Chen, Hongbin; Yu, Xiang; Zhang, Yuanming

2018-03-01

Photocatalysis has been considered to be one of the most promising ways to photodegrade organic pollutants. Herein, a series of BiOI/BiOCl films coating on FTO were fabricated through a simple method at room temperature. The photocatalytic efficiency of 30%BiOI/BiOCl could reach more than 99% aiming to degrading RhB and MB after 90 and 120 min, respectively. Compared with BiOCl, 30%BiOI/BiOCl showed 12 times higher efficiency when degrading RhB. In comparison with BiOI, 30%BiOI/BiOCl showed 5 and 6 times higher efficiency when degrading RhB and MB, respectively. These obvious enhancements were attributed to expanded visible light absorption and high separation performance of photoinduced charge. Moreover, the photocatalytic activity of 30%BiOI/BiOCl had no obvious decrease after 5 recycles, suggesting that it was a promising photocatalyst for the removal of MB and RhB pollutants. Finally, the possible growth process for the BiOI/BiOCl thin films and photocatalysis mechanism were investigated in details. This work would provide insight to the reasonable construction of BiOX heterojunction and the photocatalytic mechanism in degrading organic pollutants.

Real-time single image dehazing based on dark channel prior theory and guided filtering

NASA Astrophysics Data System (ADS)

Zhang, Zan

2017-10-01

Images and videos taken outside the foggy day are serious degraded. In order to restore degraded image taken in foggy day and overcome traditional Dark Channel prior algorithms problems of remnant fog in edge, we propose a new dehazing method.We first find the fog area in the dark primary color map to obtain the estimated value of the transmittance using quadratic tree. Then we regard the gray-scale image after guided filtering as atmospheric light map and remove haze based on it. Box processing and image down sampling technology are also used to improve the processing speed. Finally, the atmospheric light scattering model is used to restore the image. A plenty of experiments show that algorithm is effective, efficient and has a wide range of application.

Methods of alleviation of ionospheric scintillation effects on digital communications

NASA Technical Reports Server (NTRS)

Massey, J. L.

1974-01-01

The degradation of the performance of digital communication systems because of ionospheric scintillation effects can be reduced either by diversity techniques or by coding. The effectiveness of traditional space-diversity, frequency-diversity and time-diversity techniques is reviewed and design considerations isolated. Time-diversity signaling is then treated as an extremely simple form of coding. More advanced coding methods, such as diffuse threshold decoding and burst-trapping decoding, which appear attractive in combatting scintillation effects are discussed and design considerations noted. Finally, adaptive coding techniques appropriate when the general state of the channel is known are discussed.

Simultaneous determination and identity confirmation of thiodicarb and its degradation product methomyl in animal-derived foodstuffs using high-performance liquid chromatography with fluorescence detection and tandem mass spectrometry.

PubMed

Rahman, Md Musfiqur; Abd El-Aty, A M; Kim, Sung-Woo; Lee, Young-Jun; Na, Tae-Woong; Park, Joon-Seong; Shin, Ho-Chul; Shim, Jae-Han

2017-01-01

A high-performance liquid chromatography-fluorescence detection method was developed for the simultaneous determination of thiodicarb and its degradation product methomyl in animal-derived food products, including chicken muscle, beef, pork, table eggs, and milk. Thiodicarb is known to degrade during analysis; therefore, a thorough investigation was carried out, revealing that thiodicarb degrades to methomyl immediately after spiking into a matrix of animal-derived food products. Consequently, thiodicarb was determined as the sum of the parent compound and methomyl. Samples were extracted with acetonitrile and sodium salts, and purified using solid-phase extraction (SPE). The limits of detection (LODs) and quantification (LOQs) were 0.0013 and 0.004mg/kg, respectively, for both analytes in various matrices. Seven-point external calibration curves were obtained, and they showed excellent linearity with determination coefficients (R 2 )≥0.999 for all tested matrices. The method was validated at three fortification levels (LOQ, LOQ×2, and LOQ×10) in triplicate with average recoveries ranging from 84.24 to 112.8% (for methomyl) and relative standard deviations (RSDs)≤6.5% in all matrices. The converted recoveries of thiodicarb in various matrices ranged from 74.80 to 107.80% with RSDs≤4.5%. The identities of both compounds in standard solutions and for recovery were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The developed method was further validated by accurate reproduction at another laboratory. Finally, the method was applied to market samples collected from different areas (and, in the case of milk, different brands), and none of the samples tested positive for thiodicarb or methomyl. In conclusion, the developed method can be successfully applied for a single-run analysis of thiodicarb and methomyl in livestock products. Copyright © 2016 Elsevier B.V. All rights reserved.

Antioxidant Activity of the Essential Oils of Different Parts of Juniperus excelsa M. Bieb. subsp. excelsa and J. excelsa M. Bieb. subsp. polycarpos (K. Koch) Takhtajan (Cupressaceae)

PubMed Central

Emami, Sayyed Ahmad; Abedindo, Bibi Fatemeh; Hassanzadeh-Khayyat, Mohammad

2011-01-01

The essential oils of branchlets and fruits of Juniperus excelsa subsp. excelsa and Juniperus excelsa subsp. polycarpos were examined for their antioxidant activity. The compositions of the essential oils were studied by GC and GC-MS. To evaluation the antioxidants activity of the volatile oils, pure components and positive controls at different concentrations, thin-layer chromatography (TLC) screening methods, diphenylpicrylhydrazyl (DPPH) assay, deoxyribose degradation test and modified deoxyribose degradation test were employed. The results of the present study demonstrate some antioxidant activity for the tested essential oils obtained from various parts of both plants. It indicates that the use of these essential oils, in very low concentrations, may be useful as a natural preservative. However before any final conclusion, it is suggested that the antioxidant activity of these oils should also be evaluated by using lipid solvent system methods. PMID:24250416

Fungal biodegradation of anthracene-polluted cork: A comparative study.

PubMed

Jové, Patrícia; Olivella, Maria À; Camarero, Susana; Caixach, Josep; Planas, Carles; Cano, Laura; De Las Heras, Francesc X

2016-01-01

The efficiency of cork waste in adsorbing aqueous polycyclic aromatic hydrocarbons (PAHs) has been previously reported. Biodegradation of contaminated cork using filamentous fungi could be a good alternative for detoxifying cork to facilitate its final processing. For this purpose, the degradation efficiency of anthracene by three ligninolytic white-rot fungi (Phanerochaete chrysosporium, Irpex lacteus and Pleurotus ostreatus) and three non-ligninolytic fungi which are found in the cork itself (Aspergillus niger, Penicillium simplicissimum and Mucor racemosus) are compared. Anthracene degradation by all fungi was examined in solid-phase cultures after 0, 16, 30 and 61 days. The degradation products of anthracene by P. simplicissimum and I. lacteus were also identified by GC-MS and a metabolic pathway was proposed for P. simplicissimum. Results show that all the fungi tested degraded anthracene. After 61 days of incubation, approximately 86%, 40%, and 38% of the initial concentration of anthracene (i.e., 100 µM) was degraded by P. simplicissimum, P. chrysosporium and I. lacteus, respectively. The rest of the fungi degraded anthracene to a lesser extent (<30%). As a final remark, the results obtained in this study indicate that P. simplicissimum, a non-ligninolytic fungi characteristic of cork itself, could be used as an efficient degrader of PAH-contaminated cork.

Enzymes involved in the biodegradation of hexachlorocyclohexane: a mini review.

PubMed

Camacho-Pérez, Beni; Ríos-Leal, Elvira; Rinderknecht-Seijas, Noemí; Poggi-Varaldo, Héctor M

2012-03-01

The scope of this paper encompasses the following subjects: (i) aerobic and anaerobic degradation pathways of γ-hexachlorocyclohexane (HCH); (ii) important genes and enzymes involved in the metabolic pathways of γ-HCH degradation; (iii) the instrumental methods for identifying and quantifying intermediate metabolites, such as gas chromatography coupled to mass spectrometry (GC-MS) and other techniques. It can be concluded that typical anaerobic and aerobic pathways of γ-HCH are well known for a few selected microbial strains, although less is known for anaerobic consortia where the possibility of synergism, antagonism, and mutualism can lead to more particular routes and more effective degradation of γ-HCH. Conversion and removals in the range 39%-100% and 47%-100% have been reported for aerobic and anaerobic cultures, respectively. Most common metabolites reported for aerobic degradation of lindane are γ-pentachlorocyclohexene (γ-PCCH), 2,5-dichlorobenzoquinone (DCBQ), Chlorohydroquinone (CHQ), chlorophenol, and phenol, whereas PCCH, isomers of trichlorobenzene (TCB), chlorobenzene, and benzene are the most typical metabolites found in anaerobic pathways. Enzyme and genetic characterization of the involved molecular mechanisms are in their early infancy; more work is needed to elucidate them in the future. Advances have been made on identification of enzymes of Sphingomonas paucimobilis where the gene LinB codifies for the enzyme haloalkane dehalogenase that acts on 1,3,4,6-tetrachloro 1,4-cyclohexadiene, thus debottlenecking the pathway. Other more common enzymes such as phenol hydroxylase, catechol 1,2-dioxygenase, catechol 2,3-dioxygenase are also involved since they attack intermediate metabolites of lindane such as catechol and less substituted chlorophenols. Chromatography coupled to mass spectrometric detector, especially GC-MS, is the most used technique for resolving for γ-HCH metabolites, although there is an increased participation of HPLC-MS methods. Scintillation methods are very useful to assess final degradation of γ-HCH. Copyright © 2011 Elsevier Ltd. All rights reserved.

Degradation of ciprofloxacin antibiotic by Homogeneous Fenton oxidation: Hybrid AHP-PROMETHEE method, optimization, biodegradability improvement and identification of oxidized by-products.

PubMed

Salari, Marjan; Rakhshandehroo, Gholam Reza; Nikoo, Mohammad Reza

2018-09-01

The main purpose of this experimental study was to optimize Homogeneous Fenton oxidation (HFO) and identification of oxidized by-products from degradation of Ciprofloxacin (CIP) using hybrid AHP-PROMETHEE, Response Surface Methodology (RSM) and High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC-MS). At the first step, an assessment was made for performances of two catalysts (FeSO 4 ·7H 2 O and FeCl 2 ·4H 2 O) based on hybrid AHP-PROMETHEE decision making method. Then, RSM was utilized to examine and optimize the influence of different variables including initial CIP concentration, Fe 2+ concentration, [H 2 O 2 ]/[ Fe 2+ ] mole ratio and initial pH as independent variables on CIP removal, COD removal, and sludge to iron (SIR) as the response functions in a reaction time of 25 min. Weights of the mentioned responses as well as cost criteria were determined by AHP model based on pairwise comparison and then used as inputs to PROMETHEE method to develop hybrid AHP-PROMETHEE. Based on net flow results of this hybrid model, FeCl 2 ·4H 2 O was more efficient because of its less environmental stability as well as lower SIR production. Then, optimization of experiments using Central Composite Design (CCD) under RSM was performed with the FeCl 2 ·4H 2 O catalyst. Biodegradability of wastewater was determined in terms of BOD 5 /COD ratio, showing that HFO process is able to improve wastewater biodegradability from zero to 0.42. Finally, the main intermediaries of degradation and degradation pathways of CIP were investigated with (HPLC-MS). Major degradation pathways from hydroxylation of both piperazine and quinolonic rings, oxidation and cleavage of the piperazine ring, and defluorination (OH/F substitution) were suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pathway and rate-limiting step of glyphosate degradation by Aspergillus oryzae A-F02.

PubMed

Fu, Gui-Ming; Chen, Yan; Li, Ru-Yi; Yuan, Xiao-Qiang; Liu, Cheng-Mei; Li, Bin; Wan, Yin

2017-09-14

Aspergillus oryzae A-F02, a glyphosate-degrading fungus, was isolated from an aeration tank in a pesticide factory. The pathway and rate-limiting step of glyphosate (GP) degradation were investigated through metabolite analysis. GP, aminomethylphosphonic acid (AMPA), and methylamine were detected in the fermentation liquid of A. oryzae A-F02, whereas sarcosine and glycine were not. The pathway of GP degradation in A. oryzae A-F02 was revealed: GP was first degraded into AMPA, which was then degraded into methylamine. Finally, methylamine was further degraded into other products. Investigating the effects of the exogenous addition of substrates and metabolites showed that the degradation of GP to AMPA is the rate-limiting step of GP degradation by A. oryzae A-F02. In addition, the accumulation of AMPA and methylamine did not cause feedback inhibition in GP degradation. Results showed that degrading GP to AMPA was a crucial step in the degradation of GP, which determines the degradation rate of GP by A. oryzae A-F02.

Degradation properties of protein and carbohydrate during sludge anaerobic digestion.

PubMed

Yang, Guang; Zhang, Panyue; Zhang, Guangming; Wang, Yuanyuan; Yang, Anqi

2015-09-01

Degradation of protein and carbohydrate is vital for sludge anaerobic digestion performance. However, few studies focused on degradation properties of protein and carbohydrate. This study investigated detailed degradation properties of sludge protein and carbohydrate in order to gain insight into organics removal during anaerobic digestion. Results showed that carbohydrate was more efficiently degraded than protein and was degraded prior to protein. The final removal efficiencies of carbohydrate and protein were 49.7% and 32.2%, respectively. The first 3 days were a lag phase for protein degradation since rapid carbohydrate degradation in this phase led to repression of protease formation. Kinetics results showed that, after initial lag phase, protein degradation followed the first-order kinetic with rate constants of 0.0197 and 0.0018 d(-1) during later rapid degradation phase and slow degradation phase, respectively. Carbohydrate degradation also followed the first-order kinetics with a rate constant of 0.007 d(-1) after initial quick degradation phase. Copyright © 2015 Elsevier Ltd. All rights reserved.

Targeted polypeptide degradation

DOEpatents

Church, George M [Brookline, MA; Janse, Daniel M [Brookline, MA

2008-05-13

This invention pertains to compositions, methods, cells and organisms useful for selectively localizing polypeptides to the proteasome for degradation. Therapeutic methods and pharmaceutical compositions for treating disorders associated with the expression and/or activity of a polypeptide by targeting these polypeptides for degradation, as well as methods for targeting therapeutic polypeptides for degradation and/or activating therapeutic polypeptides by degradation are provided. The invention provides methods for identifying compounds that mediate proteasome localization and/or polypeptide degradation. The invention also provides research tools for the study of protein function.

On-orbit degradation of recent space-based solar instruments and understanding of the degradation processes

NASA Astrophysics Data System (ADS)

Meftah, M.; Dominique, M.; BenMoussa, A.; Dammasch, I. E.; Bolsée, D.; Pereira, N.; Damé, L.; Bekki, S.; Hauchecorne, A.

2017-05-01

The space environment is considered hazardous to spacecraft, resulting in materials degradation. Understanding the degradation of space-based instruments is crucial in order to achieve the scientific objectives, which are derived from these instruments. This paper discusses the on-orbit performance degradation of recent spacebased solar instruments. We will focus on the instruments of three space-based missions such as the Project for On-Board Autonomy 2 (PROBA2) spacecraft, the Solar Monitoring Observatory (SOLAR) payload onboard the Columbus science Laboratory of the International Space Station (ISS) and the PICARD spacecraft. Finally, this paper intends to understand the degradation processes of these space-based solar instruments.

Method of assessing the state of a rolling bearing based on the relative compensation distance of multiple-domain features and locally linear embedding

NASA Astrophysics Data System (ADS)

Kang, Shouqiang; Ma, Danyang; Wang, Yujing; Lan, Chaofeng; Chen, Qingguo; Mikulovich, V. I.

2017-03-01

To effectively assess different fault locations and different degrees of performance degradation of a rolling bearing with a unified assessment index, a novel state assessment method based on the relative compensation distance of multiple-domain features and locally linear embedding is proposed. First, for a single-sample signal, time-domain and frequency-domain indexes can be calculated for the original vibration signal and each sensitive intrinsic mode function obtained by improved ensemble empirical mode decomposition, and the singular values of the sensitive intrinsic mode function matrix can be extracted by singular value decomposition to construct a high-dimensional hybrid-domain feature vector. Second, a feature matrix can be constructed by arranging each feature vector of multiple samples, the dimensions of each row vector of the feature matrix can be reduced by the locally linear embedding algorithm, and the compensation distance of each fault state of the rolling bearing can be calculated using the support vector machine. Finally, the relative distance between different fault locations and different degrees of performance degradation and the normal-state optimal classification surface can be compensated, and on the basis of the proposed relative compensation distance, the assessment model can be constructed and an assessment curve drawn. Experimental results show that the proposed method can effectively assess different fault locations and different degrees of performance degradation of the rolling bearing under certain conditions.

Validation of RP-HPLC method and stress degradation for the combination of metformin HCl, atorvastatin calcium and glimepiride: application to nanoparticles.

PubMed

Gite, Sandip; Patravale, Vandana

2015-01-01

A stability-indicating high-performance liquid chromatography (HPLC) procedure was developed for the determination of metformin HCl (MTH), atorvastatin calcium (AC) and glimepiride (GP) in combination and their main degradation products. The separation and quantization were achieved on a 5-µm Qualisil gold, C18 column (4.6 mm × 250 mm). The mobile phase selected was phosphate buffer (pH 2.9)-organic phase in proportion of 70:30. Organic phase consisted of methanol-acetonitrile (90:10) at a flow rate of 1 mL/min and detection of analytes was carried out at 230 nm. The method exhibited good linearity over the range of 10-60 µg/mL for MTH, 2-20 µg/mL for AC and 5-30 µg/mL for GP. Square of the correlation coefficients was found to be >0.999. Various stress degradation studies were carried out in combination as per International Conference of Harmonization (ICH) guidelines for 4 h. The recovery and precision were determined in terms of intraday and interday precisions and expressed as relative standard deviations. These were <1 and <2%, respectively. Finally, the applicability of the method was evaluated in nanoparticle analysis of MTH, AC and GP as well as in stability studies of nanoformulation. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Multiscale Concrete Modeling of Aging Degradation

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

Hammi, Yousseff; Gullett, Philipp; Horstemeyer, Mark F.

In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Ginermore » et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].« less

Phytoremediation-biorefinery tandem for effective clean-up of metal contaminated soil and biomass valorisation.

PubMed

Sotenko, Maria; Coles, Stuart; Barker, Guy; Song, Lijiang; Jiang, Ying; Longhurst, Philip; Romanova, Tamara; Shuvaeva, Olga; Kirwan, Kerry

2017-11-02

During the last few decades, phytoremediation process has attracted much attention because of the growing concerns about the deteriorating quality of soil caused by anthropogenic activities. Here, a tandem phytoremediation/biorefinery process was proposed as a way to turn phytoremediation into a viable commercial method by producing valuable chemicals in addition to cleaned soil. Two agricultural plants (Sinapis alba and Helianthus annuus) were grown in moderately contaminated soil with ca. 100 ppm of Ni and further degraded by a fungal lignin degrader-Phanerochaete chrysosporium. Several parameters have been studied, including the viability of plants, biomass yield, and their accumulating and remediating potentials. Further, downstream processing showed that up to 80% of Ni can be easily extracted from contaminated biomass by aqueous extraction at mild conditions. Finally, it was demonstrated that the growth of plants on the contaminated soil could be degraded by P. chrysosporium, and the effect of nickel and biomass pretreatment on the solid-state fermentation was studied. The proposed and studied methodology in this work could pave the way for successful commercialization of the phytoremediation process in the near future.

Treatment of simulated wastewater containing Reactive Red 195 by zero-valent iron/activated carbon combined with microwave discharge electrodeless lamp/sodium hypochlorite.

PubMed

Fu, Jie; Xu, Zhen; Li, Qing-Shan; Chen, Song; An, Shu-Qing; Zeng, Qing-Fu; Zhu, Hai-Liang

2010-01-01

A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaClO) and the combination of ZVI/AC-MDEL/NaClO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaClO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaClO, we found that in the ZVI/AC-MEDL/NaClO process, ZVI/AC could break the azo bond firstly and then MEDL/NaClO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.

Transfer Printing Method to Obtain Polarized Light Emission in Organic Light-Emitting Device

NASA Astrophysics Data System (ADS)

Noh, Hee Yeon; Park, Chang-sub; Park, Ji-Sub; Kang, Shin-Won; Kim, Hak-Rin

2012-06-01

We demonstrate a transfer printing method to obtain polarized light emission in organic light-emitting devices (OLEDs). On a rubbed self-assembled monolayer (SAM), a spin-coated liquid crystalline light-emissive polymer is aligned along the rubbing direction because of the anisotropic interfacial intermolecular interaction. Owing to the low surface energy of the SAM surface, the light-emissive layer was easily transferred to a patterned poly(dimethylsiloxane) (PDMS) stamp surface without degrading the ordering. Finally, a polarized light-emissive OLED device was prepared by transferring the patterned light-emissive layer to the charge transport layer of the OLED structure.

Stability of Materials in High Temperature Water Vapor: SOFC Applications

NASA Technical Reports Server (NTRS)

Opila, E. J.; Jacobson, N. S.

2010-01-01

Solid oxide fuel cell material systems require long term stability in environments containing high-temperature water vapor. Many materials in fuel cell systems react with high-temperature water vapor to form volatile hydroxides which can degrade cell performance. In this paper, experimental methods to characterize these volatility reactions including the transpiration technique, thermogravimetric analysis, and high pressure mass spectrometry are reviewed. Experimentally determined data for chromia, silica, and alumina volatility are presented. In addition, data from the literature for the stability of other materials important in fuel cell systems are reviewed. Finally, methods for predicting material recession due to volatilization reactions are described.

Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression

DOEpatents

Douglas, David R [Newport News, VA; Tennant, Christopher D [Williamsburg, VA

2012-07-10

A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

Varying Conditions for Hexanoic Acid Degradation with BioTiger™

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

Foreman, Koji; Milliken, Charles; Brigmon, Robin

BioTiger™ (BT) is a consortium of 12 bacteria designed for petroleum waste biodegradation. BT is currently being studied and could be considered for bioremediation of the Athabasca oil sands refineries in Canada and elsewhere. The run-off ponds from the petroleum extraction processes, called tailings ponds, are a mixture of polycyclic aromatic hydrocarbons, naphthenic acids, hydrocarbons, toxic chemicals like heavy metals, water, and sand. Due to environmental regulations the oil industry would like to separate and degrade the hazardous chemical species from the tailings ponds while recycling the water. It has been shown that BT at 30 C° is able tomore » completely degrade 10 mM hexanoic acid (HA) co-metabolically with 0.2% yeast extract (w/v) in 48 hours when starting at 0.4 OD 600nm. After establishing this stable degradation capability, variations were tested to explore the wider parameters of BT activity in temperature, pH, intermediate degradation, co-metabolic dependence, and transfer stability. Due to the vast differences in temperature at various points in the refineries, a wide range of temperatures were assessed. The results indicate that BT retains the ability to degrade HA, a model surrogate for tailings pond contaminants, at temperatures ranging from 15°C to 35°C. Hexanamide (HAM) was shown to be an intermediate generated during the degradation of HA in an earlier work and HAM is completely degraded after 48 hours, indicating that HAM is not the final product of HA degradation. Various replacements for yeast extract were attempted. Glucose, a carbon source; casein amino acids, a protein source; additional ammonia, mimicking known media; and additional phosphate with Wolffe’s vitamins and minerals all showed no significant degradation of HA compared to control. Decreasing the yeast extract concentration (0.05%) demonstrated limited but significant degradation. Finally, serial inoculations of BT were performed to determine the stability of degradation over several generations. Overall, BT has shown to be moderately flexible for HA co-metabolic biodegradation.« less

Summary Report of Cable Aging and Performance Data for Fiscal Year 2014.

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

Celina, Mathias C.; Celina, Mathias C.; Redline, Erica Marie

2014-09-01

As part of the Light Water Reactor Sustainability Program, science - based engineering approaches were employed to address cable degradation behavior under a range of exposure environments. Experiments were conducted with the goal to provide best guidance for aged material states, remaining life and expected performance under specific conditions for a range of cable materials. Generic engineering tests , which focus on rapid accelerated aging and tensile elongation , were combined with complementar y methods from polymer degradation science. Sandia's approach, building on previous years' efforts, enabled the generation of some of the necessary data supporting the development of improvedmore » lifetime predictions models, which incorporate known material b ehaviors and feedback from field - returned 'aged' cable materials. Oxidation rate measurements have provided access to material behavior under low dose rate thermal conditions, where slow degradation is not apparent in mechanical property changes. Such da ta have shown aging kinetics consistent with established radiati on - thermal degradation models. ACKNOWLEDGEMENTS We gratefully acknowledge ongoing technical support at the LICA facility and extensive sample handling provided by Maryla Wasiolek and Don Hans on. Sam Durbin and Patrick Mattie are recognized for valuable guidance throughout the year and assistance in the preparation of the final report. Doug Brunson is appreciated for sample analysis, compilation and plotting of experimental data.« less

Biosynthesis and Degradation of Mono-, Oligo-, and Polysaccharides: Introduction

NASA Astrophysics Data System (ADS)

Wilson, Iain B. H.

Glycomolecules, whether they be mono-, oligo-, or polysaccharides or simple glycosides, are—as any biological molecules—the products of biosynthetic processes; on the other hand, at the end of their lifespan, they are also subject to degradation. The beginning point, biochemically, is the fixation of carbon by photosynthesis; subsequent metabolism in plants and other organisms results in the generation of the various monosaccharides. These must be activated—typically as nucleotide sugars or lipid-phosphosugars—before transfer by glycosyltransferases can take place in order to produce the wide variety of oligo- and polysaccharides seen in Nature; complicated remodelling processes may take place—depending on the pathway—which result in partial trimming of a precursor by glycosidases prior to the addition of further monosaccharide units. Upon completion of the 'life' of a glycoconjugate, glycosidases will degrade the macromolecule finally into monosaccharide units which can be metabolized or salvaged for incorporation into new glycan chains. In modern glycoscience, a wide variety of methods—genetic, biochemical, analytical—are being employed in order to understand these various pathways and to place them within their biological and medical context. In this chapter, these processes and relevant concepts and methods are introduced, prior to elaboration in the subsequent more specialized chapters on biosynthesis and degradation of mono-, oligo-, and polysaccharides.

Study of degradation behaviour of montelukast sodium and its marketed formulation in oxidative and accelerated test conditions and prediction of physicochemical and ADMET properties of its degradation products using ADMET Predictor™.

PubMed

Tiwari, Shobhit Kumar; Singh, Dilip Kumar; Ladumor, Mayurbhai Kathadbhai; Chakraborti, Asit K; Singh, Saranjit

2018-05-26

Study of oxidative stability of pharmaceutical actives and formulations is important as oxidation pathway is the second most significant route for the decay of pharmaceuticals. Montelukast sodium, a leukotriene receptor antagonist, is prone to oxidation reactions owing to sensitive moieties in its structure. It is also known to be light sensitive. This study was aimed to understand the degradation behaviour of the drug in different oxidative media containing hydrogen peroxide, AIBN, Fe 3+ , Fenton's reagent and O 2 environment under normal laboratory light conditions. The degradation behaviour of the drug was also evaluated in solid sate under ICH recommended accelerated stability condition of 40 °C/75% RH to correlate with the degradation products (DPs) formed in a solid oral formulation. A total of nine DPs (MTK 1 to MTK 9) were formed from both the drug substance and the marketed tablet formulation on storage under controlled oxygen environment in normal laboratory light and temperature conditions. These DPs were well separated on a C-18 column using a gradient HPLC method. The characterization of DPs was done based on HRMS and multi-stage tandem mass spectrometric (MS n ) data. The knowledge of the structure of DPs helped in laying down degradation pathway of the drug. Also, mechanism for the formation of each DP was postulated. Finally, physicochemical as well as absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the DPs were predicted by ADMET Predictor™ software. Copyright © 2018 Elsevier B.V. All rights reserved.

Complex Degradation Processes Lead to Non-Exponential Decay Patterns and Age-Dependent Decay Rates of Messenger RNA

PubMed Central

Deneke, Carlus; Lipowsky, Reinhard; Valleriani, Angelo

2013-01-01

Experimental studies on mRNA stability have established several, qualitatively distinct decay patterns for the amount of mRNA within the living cell. Furthermore, a variety of different and complex biochemical pathways for mRNA degradation have been identified. The central aim of this paper is to bring together both the experimental evidence about the decay patterns and the biochemical knowledge about the multi-step nature of mRNA degradation in a coherent mathematical theory. We first introduce a mathematical relationship between the mRNA decay pattern and the lifetime distribution of individual mRNA molecules. This relationship reveals that the mRNA decay patterns at steady state expression level must obey a general convexity condition, which applies to any degradation mechanism. Next, we develop a theory, formulated as a Markov chain model, that recapitulates some aspects of the multi-step nature of mRNA degradation. We apply our theory to experimental data for yeast and explicitly derive the lifetime distribution of the corresponding mRNAs. Thereby, we show how to extract single-molecule properties of an mRNA, such as the age-dependent decay rate and the residual lifetime. Finally, we analyze the decay patterns of the whole translatome of yeast cells and show that yeast mRNAs can be grouped into three broad classes that exhibit three distinct decay patterns. This paper provides both a method to accurately analyze non-exponential mRNA decay patterns and a tool to validate different models of degradation using decay data. PMID:23408982

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.

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.

Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska

NASA Technical Reports Server (NTRS)

Gaines, G. B.; Thomas, R. E.; Noel, G. T.; Shilliday, T. S.; Wood, V. E.; Carmichael, D. C.

1979-01-01

Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

Efficiency of a bagasse substrate in a biological bed system for the degradation of glyphosate, malathion and lambda-cyhalothrin under tropical climate conditions.

PubMed

de Roffignac, Laure; Cattan, Philippe; Mailloux, Julie; Herzog, David; Le Bellec, Fabrice

2008-12-01

After the rinsing of spray equipment, the rinsing water contains polluting products. One way to avoid pollution is to bring the rinsing water over a purification system, a biological bed. The system consists of an impermeable tub filled with a biomix substrate that facilitates biodegradation of pesticides. Usually, straw is one component of the biomix. The objective of this study was to assess the efficiency of an unusual substrate, bagasse, a residue of sugar cane, for the degradation of three pesticides, glyphosate, malathion and lambda-cyhalothrin. Results showed that more than 99% of malathion and glyphosate were degraded in 6 months. In the biological bed, the DT(50) value for malathion was 17 days, for glyphosate 33 days and for lambda-cyhalothrin 43 days. The degradation rate of aminomethylphosphonic acid (AMPA) residues from the degradation of glyphosate was slower than that of the other pesticides (DT(50) 69 days). Finally, the innocuousness of the biomix after 6 months of degradation was confirmed by biological tests. Although the degradation rates of the three pesticides in the present bagasse-based system were similar to those under temperate conditions, the degradation conditions were improved by comparison with those in soil under the given tropical conditions. Further benefits of this system are pesticide confinement, to avoid their dispersion in the environment by liquids or solids, and a lower overall cost. Finally, possibilities for optimising the bagasse-based system (e.g. management of the water content and nature of the biomix) are discussed.

Evaluation of Carbon Anodes for Rechargeable Lithium Cells

NASA Technical Reports Server (NTRS)

Huang, C-K.; Surampudi, S.; Attia, A.; Halpert, G.

1993-01-01

Both liquid phase intercalation technique and electrochemical intercalation technique were examined for the Li-carbon material preparation. The electrochemical techniques include a intermittent discharge method and a two step method. These two electrochemical techniques can ensure to achieve the maximum reversible Li capacity for common commercially available carbon materials. The carbon materials evaluated by the intercalacation method includes: pitch coke, petroleum cole, PAN fiber and graphite materials. Their reversible Li capacity were determined and compared. In this paper, we also demonstrate the importance of EPDM binder composition in the carbon electrode. Our results indicated that it can impact the Li intercalation and de-intercalation capacity in carbon materials. Finally, two possibilities that may help explain the capacity degradation during practical cell cycling were proposed.

MALDI, AP/MALDI and ESI techniques for the MS detection of amyloid [beta]-peptides

NASA Astrophysics Data System (ADS)

Grasso, Giuseppe; Mineo, Placido; Rizzarelli, Enrico; Spoto, Giuseppe

2009-04-01

Amyloid [beta]-peptides (A[beta]s) are involved in several neuropathological conditions such as Alzheimer's disease and considerable experimental evidences have emerged indicating that different proteases play a major role in regulating the accumulation of A[beta]s in the brain. Particularly, insulin-degrading enzyme (IDE) has been shown to degrade A[beta]s at different cleavage sites, but the experimental results reported in the literature and obtained by mass spectrometry methods are somehow fragmentary. The detection of A[beta]s is often complicated by solubility issues, oxidation artifacts and spontaneous aggregation/cleavage and, in order to rationalize the different reported results, we analyzed A[beta]s solutions by three different MS approaches: matrix assisted laser desorption ionization-time of flight (MALDI-TOF), atmospheric pressure (AP) MALDI ion trap and electrospray ionization (ESI) ion trap. Differences in the obtained results are discussed and ESI is chosen as the most suitable MS method for A[beta]s detection. Finally, cleavage sites produced by interaction of A[beta]s with IDE are identified, two of which had never been reported in the literature.

Functional role of R462 in the degradation of hyaluronan catalyzed by hyaluronate lyase from Streptococcus pneumoniae.

PubMed

Li, Fengxue; Xu, Dingguo

2015-08-01

Hyaluronan lyase from Streptococcus pneumoniae can degrade hyaluronic acid, which is one of the major components in the extracellular matrix. Hyaluronan can regulate water balance, osmotic pressure, and act as an ion exchange resin. Followed by our recent work on the catalytic reaction mechanism and substrate binding mode, we in this work further investigate the functional role of active site arginine residue, R462, in the degradation of hyaluronan. The site directed mutagenesis simulation of R462A and R462Q were modeled using a combined quantum mechanical and molecular mechanical method. The overall substrate binding features upon mutations do not have significant changes. The energetic profiles for the reaction processes are essentially the same as that in wild type enzyme, but significant activation barrier height changes can be observed. Both mutants were shown to accelerate the overall enzymatic activity, e.g., R462A can reduce the barrier height by about 2.8 kcal mol(-1), while R462Q reduces the activation energy by about 2.9 kcal mol(-1). Consistent with the active site model calculated using density functional theory, our results can support that the positive charge on R462 guanidino side chain group plays a negative role in the catalysis. Finally, the functional role of R462 was proposed to facilitate the formation of initial enzyme-substrate complex, but not in the subsequent catalytic degradation reaction. Graphical Abstract Degradation of hyaluronan catalyzed by hyaluronate lyase from Streptococcus pneumoniae.

Effective removal of the antibiotic Nafcillin from water by combining the Photoelectro-Fenton process and Anaerobic Biological Digestion.

PubMed

Vidal, Jorge; Huiliñir, Cesar; Santander, Rocío; Silva-Agredo, Javier; Torres-Palma, Ricardo A; Salazar, Ricardo

2018-05-15

The elimination of the antibiotic Nafcillin (NAF), which is usually used in hospitals and veterinary clinics around the world, was assessed through a combination of three advanced electrochemical oxidation processes followed by anaerobic digestion process. In the first stage different electrochemical advanced oxidation processes (EAOPs) were used: electro-oxidation with hydrogen peroxide (EO-H 2 O 2 ), electro-Fenton (EF) and Photo electro-Fenton (PEF). After PEF, almost complete and highly efficient degradation and elimination of NAF was achieved, with the concomitant elimination of the associated antimicrobial activity. The fast degradation rate produced by PEF is explained by the oxidative action of hydroxyl radicals (•OH) together with the direct UV photolysis of complexes formed between Fe 3+ and some organic intermediates. Total removal of NAF occurs after 90min of electrolysis by PEF, with the generation of organic intermediates that remain in solution. However, when this post PEF process solution was treated with an anaerobic biological process, the intermediates generated in the electrochemical degradation of NAF were completely eliminated after 24h. The kinetic degradation of NAF as well as the identification/quantification of products and intermediates formed during the degradation of antibiotic, such as inorganic ions, carboxylic acids and aromatic compounds, were determined by chromatographic and photometric methods. Finally, an oxidation pathway is proposed for the complete conversion to CO 2 . Copyright © 2017 Elsevier B.V. All rights reserved.

Metal Artifact Suppression in Dental Cone Beam Computed Tomography Images Using Image Processing Techniques

PubMed Central

Johari, Masoumeh; Abdollahzadeh, Milad; Esmaeili, Farzad; Sakhamanesh, Vahideh

2018-01-01

Background: Dental cone beam computed tomography (CBCT) images suffer from severe metal artifacts. These artifacts degrade the quality of acquired image and in some cases make it unsuitable to use. Streaking artifacts and cavities around teeth are the main reason of degradation. Methods: In this article, we have proposed a new artifact reduction algorithm which has three parallel components. The first component extracts teeth based on the modeling of image histogram with a Gaussian mixture model. Striking artifact reduction component reduces artifacts using converting image into the polar domain and applying morphological filtering. The third component fills cavities through a simple but effective morphological filtering operation. Results: Finally, results of these three components are combined into a fusion step to create a visually good image which is more compatible to human visual system. Conclusions: Results show that the proposed algorithm reduces artifacts of dental CBCT images and produces clean images. PMID:29535920

Microbial degradation of poly-b-esters: A mechanistic study, cellulose acetate biodegradability. Final report, 1 May 1990-31 July 1993

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

Gross, R.A.

1993-08-30

In this Final Report, work carried out under ARO grant C-DAAL03-G-0111 is described. The investigations performed include the following: (1) isolation, purification and characterization of a poly(3-hydroxybutyrate) depolymerase enzyme from Penicillium funiculosum, (2) determination that the depolymerase is a serine esterase, (3) study of the effect of polymer stereochemistry and crystalline order in a semi-crystalline polymer film substrate on enzyme specificity and activity, (3) isolation, purification and characterization of cellulose acetate degrading microorganisms and (4) determination of the biodegradability of cellulose acetate with degrees of substitution up to 2.5 under aerobic thermophilic conditions. Poly(3-hydroxybutyrate) biodegradation, Poly(3-hydroxybutyrate) depolymerase enzyme, Depolymerase frommore » Penicillium funiculosum, Cellulose acetate degrading microorganisms, Composting polymer biodegradable.« less

[Determination of myclobutanil 25% WG degradation dynamics in ginseng root, stem, leaf and soil by HPLC-MS/MS].

PubMed

Wang, Yan; Wang, Chun-Wei; Gao, Jie; Cui, Li-Li; Xu, Yun-Cheng

2014-07-01

A high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method was developed for determining degradation dynamics and final residues of myclobutanil 25% WG in ginseng root, stem, leaf and soil. The samples were extracted with acetonitrile, cleaned-up with primary secondary amine (PSA) solid phase extraction cartridge, separated by Kromasil Eternity-5-C18 (2.1 mm x 150 mm, 5 microm) column with a gradient of acetonitrile and 0.1% formate in water as mobile phases, and analyzed with the multiple reaction monitoring (MRM) in positive ion mode by employing the external standard method. The average recoveries and the relative standard derivations (RSDs) of myclobutanil at the spiked level of 0.01-0.20 mg x kg(-1) were 80.9%-90.7% and 5.54%-9.29%, respectively, and the limit of quantification (LOQ) was 0.005 mg x kg(-1). The method with good reproducible, high precision and low detection limit could meet the requirements of residual analysis on ginseng production. The half-lives of myclobutanil were from 6.25 days to 9.94 days in ginseng root, stem, leaf and soil at spraying dosage of 1 152 g x hm(-2) The final residues were below 0.060 1 mg x kg(-1) in root, below 0.081 7 mg x kg(-1) in stem, 0.006 0-0.102 2 mg x kg(-1) in leaf and below 0.037 6 mg x kg(-1) in soil at spraying dosage range from 576 to 1 152 g x hm(-2). It is recommended that the MRLs of myclobutanil in dried ginseng may be suggested to be 0.10 mg x kg(-1) temporarily, and the preharvest interval was set at 35 days.

Study on degenerate coefficient and degeneration evaluation of lithium-ion battery

NASA Astrophysics Data System (ADS)

Li, Bei; Li, Xiaopeng

2017-07-01

Some characteristic parameters were epurated in this paper by analyzing internal and external factors of the degradation degree of lithium-ion battery. These characteristic parameters include open circuit voltage (OCV), state of charge (SOC) and ambient temperature. The degradation degree was evaluated by discrete degree of the array, which is composed of the above parameters. The epurated parameters were verified through adaptive neuro-fuzzy inference system (ANFIS) model building. The expression of degradation coefficient was finally determined. The simulation results show that the expression is reasonable and precise to describe the degradation degree.

Cultivation of a bacterial consortium with the potential to degrade total petroleum hydrocarbon using waste activated sludge.

PubMed

Sivakumar, S; Song, Y C; Kim, S H; Jang, S H

2015-11-01

Waste activated sludge was aerobically treated to demonstrate multiple uses such as cultivating an oil degrading bacterial consortium; studying the influence of a bulking agent (peat moss) and total petroleum hydrocarbon concentration on bacterial growth and producing a soil conditioner using waste activated sludge. After 30 days of incubation, the concentration of oil-degrading bacteria was 4.3 x 10(8) CFU g(-1) and 4.5 x 10(8) CFU g(-1) for 5 and 10 g of total petroleum hydrocarbon, respectively, in a mixture of waste activated sludge (1 kg) and peat moss (0.1 kg). This accounts for approximately 88.4 and 91.1%, respectively, of the total heterotrophic bacteria (total-HB). The addition of bulking agent enhanced total-HB population and total petroleum hydrocarbon-degrading bacterial population. Over 90% of total petroleum hydrocarbon degradation was achieved by the mixture of waste activated sludge, bulking agent and total petroleum hydrocarbon. The results of physico-chemical parameters of the compost (waste activated sludge with and without added peat moss compost) and a substantial reduction in E. coli showed that the use of this final product did not exhibit risk when used as soil conditioner. Finally, the present study demonstrated that cultivation of total petroleum hydrocarbon-degrading bacterial consortium and production of compost from waste activated sludge by aerobic treatment was feasible.

MS2/TOF and LC-MS/TOF studies on toremifene to characterize its forced degradation products.

PubMed

Bansal, Gulshan; Maddhesia, Pawan K; Bansal, Yogita

2011-12-21

The present study was designed to characterize the possible degradation products of toremifene under varied conditions as prescribed by ICH guidelines Q1A(R2). The forced degradation studies were conducted on toremifene citrate under the conditions of hydrolysis (acidic, basic and neutral), photolysis, oxidation and dry heat. The drug was found unstable to photolysis and hydrolysis in water and acidic media but stable to alkaline hydrolysis, peroxide oxidation and thermal degradation. In total fifteen degradation products (I-XV) were formed, which were resolved from each other and the drug on a C-18 column employing an isocratic elution method. A complete mass fragmentation pattern of the drug was established with the help of LC/ESI-MS/TOF to assist characterization of the degradation products. Of the fifteen products, six products III, IV, VII, VIII, XIV and XV were detected in LC-MS. The molecular masses of III, IV, VII and VIII were found to be the same i.e., 387, while those of XIV and XV were 389 and 403, respectively. Structures of these products were elucidated through comparison of their mass fragmentation patterns with the drug, which were proposed on the basis of accurate masses of the parent and fragment ions. These were characterized as (Z)-2-(2-(dimethylamino)ethyl)-4-(4-hydroxy-1,2-diphenylbut-1-enyl)phenol (III), (E)-2-(2-(dimethylamino)ethyl)-4-(4-hydroxy-1,2-diphenylbut-1-enyl)phenol (IV), (E)-4-(4-(2-(dimethylamino)ethoxy)phenyl)-3,4-diphenylbut-3-en-1-ol (VII), (Z)-4-(4-(2-(dimethylamino)ethoxy)phenyl)-3,4-diphenylbut-3-en-1-ol (VIII), 2-(4-(10-(2-chloroethyl)phenanthren-9-yl)phenoxy)-N-methylethanamine (XIV), and 2-(4-(10-(2-chloroethyl)phenanthren-9-yl)phenoxy)-N,N-dimethylethanamine (XV). Finally, a most plausible mechanistic explanation for degradation of the drug in different chemical environments is also proposed. The results of the study disclose six new degradation related impurities of the drug.

Exacerbated grassland degradation and desertification in Central Asia during 2000-2014.

PubMed

Zhang, Geli; Biradar, Chandrashekhar M; Xiao, Xiangming; Dong, Jinwei; Zhou, Yuting; Qin, Yuanwei; Zhang, Yao; Liu, Fang; Ding, Mingjun; Thomas, Richard J

2018-03-01

Grassland degradation and desertification is a complex process, including both state conversion (e.g., grasslands to deserts) and gradual within-state change (e.g., greenness dynamics). Existing studies hardly separated the two components and analyzed it as a whole based on time series vegetation index data, which cannot provide a clear and comprehensive picture for grassland degradation and desertification. Here we propose an integrated assessment strategy, by considering both state conversion and within-state change of grasslands, to investigate grassland degradation and desertification process in Central Asia. First, annual maps of grasslands and sparsely vegetated land were generated to track the state conversions between them. The results showed increasing grasslands were converted to sparsely vegetated lands from 2000 to 2014, with the desertification region concentrating in the latitude range of 43-48° N. A frequency analysis of grassland vs. sparsely vegetated land classification in the last 15 yr allowed a recognition of persistent desert zone (PDZ), persistent grassland zone (PGZ), and transitional zone (TZ). The TZ was identified in southern Kazakhstan as one hotspot that was unstable and vulnerable to desertification. Furthermore, the trend analysis of Enhanced Vegetation Index during thermal growing season (EVI TGS ) was investigated in individual zones using linear regression and Mann-Kendall approaches. An overall degradation across the area was found; moreover, the second desertification hotspot was identified in northern Kazakhstan with significant decreasing in EVI TGS , which was located in PGZ. Finally, attribution analyses of grassland degradation and desertification were conducted by considering precipitation, temperature, and three different drought indices. We found persistent droughts were the main factor for grassland degradation and desertification in Central Asia. Considering both state conversion and gradual within-state change processes, this study provided reference information for identification of desertification hotspots to support further grassland degradation and desertification treatment, and the method could be useful to be extended to other regions. © 2017 by the Ecological Society of America.

Biotransformation and Detoxification of Xylidine Orange Dye Using Immobilized Cells of Marine-Derived Lysinibacillus sphaericus D3

PubMed Central

Devi, Prabha; Wahidullah, Solimabi; Sheikh, Farhan; Pereira, Rochelle; Narkhede, Niteen; Amonkar, Divya; Tilvi, Supriya; Meena, Ram Murthy

2017-01-01

Lysinibacillus sphaericus D3 cell-immobilized beads in natural gel sodium alginate decolorized the xylidine orange dye 1-(dimethylphenylazo)-2-naphthol-6-sulfonic acid sodium salt in the laboratory. Optimal conditions were selected for decolorization and the products formed were evaluated for toxicity by disc diffusion assay against common marine bacteria which revealed the non-toxic nature of the dye-degraded products. Decolorization of the brightly colored dye to colorless products was measured on an Ultra Violet-Vis spectrophotometer and its biodegradation products monitored on Thin Layer Chromatographic plate and High Performance Liquid Chromatography (HPLC). Finally, the metabolites formed in the decolorized medium were characterized by mass spectrometry. This analysis confirms the conversion of the parent molecule into lower molecular weight aromatic phenols and sulfonic acids as the final products of biotransformation. Based on the results, the probable degradation products of xylidine orange were naphthol, naphthylamine-6-sulfonic acid, 2-6-dihydroxynaphthalene, and bis-dinaphthylether. Thus, it may be concluded that the degradation pathway of the dye involved (a) reduction of its azo group by azoreductase enzyme (b) dimerization of the hydrazo compound followed by (c) degradation of monohydrazo as well as dimeric metabolites into low molecular weight aromatics. Finally, it may be worth exploring the possibility of commercially utilizing L. sphaericus D3 for industrial applications for treating large-scale dye waste water. PMID:28208715

On the Identication of Wrinkles of Membrane by Traveling Elastic Wave

NASA Astrophysics Data System (ADS)

Akaike, Yusuke; Yokozeki, Tomhiro

2012-07-01

Wrinkling is one of the critical factors that degrade the performance of space membrane structures. This paper proposes the way to detect the size and the position of wrinkles by observing reflection of the elastic waves at the boundary between the wrinkled section and the flat section. A wrinkle is modeled as a part of an annulus, and the effects of thickness, material properties and curvature of the membrane on the reflection rates of elastic waves are investigated. Finally, the proposed identification method is experimentally demonstrated.

Gold ink coating of thermocouple sheaths

DOEpatents

Ruhl, H. Kenneth

1992-01-01

A method is provided for applying a gold ink coating to a thermocouple sheath which includes the steps of electropolishing and oxidizing the surface of the thermocouple sheath, then dipping the sheath into liquid gold ink, and finally heat curing the coating. The gold coating applied in this manner is highly reflective and does not degrade when used for an extended period of time in an environment having a temperature over 1000.degree. F. Depending on the application, a portion of the gold coating covering the tip of the thermocouple sheath is removed by abrasion.

Environmental Degradation of Fuels, Fluids and Related Materials for Aircraft

DTIC Science & Technology

1976-03-01

23. As a final step of this treatment, the tube is rinsed with hot (200*F) 5% oxalic acid solution to remove metal oxides and com- plex salts. This...of DuPont Method for Deter- 70 mination of DCI-4A Corrosion Inhibitor D. Determination of Total Acid Number for 71 Coirosion Inhibitor No. 4269-28 E...Analyses of Hydrocarbon Fuels 58 18 Heat of Combustion of Benzoic Acid 60 19 Heat of Combustion Values for Ten JP-4 Specimens 61 ix -I /𔃻 " ’ List of Tables

Discrimination among iron sulfide species formed in microbial cultures.

PubMed

Popa, R; Kinkle, B K

2000-10-01

A quantitative method for the study of iron sulfides precipitated in liquid cultures of bacteria is described. This method can be used to quantify and discriminate among amorphous iron sulfide (FeS(amorph)), iron monosulfide minerals such as mackinawite or greigite (FeS(min)), and iron disulfide minerals such as pyrite or marcasite (FeS(2min)) formed in liquid cultures. Degradation of iron sulfides is performed using a modified Cr(2+) reduction method with reflux distillation. The basic steps of the method are: first, separation of FeS(amorph); second, elimination of interfering species of S such as colloidal sulfur (S(c) degrees ), thiosulphate (S(2)O(3)(2-)) and polysulfides (S(x)(2-)); third, separation of FeS(min); and fourth, separation of FeS(2min). The final product is H(2)S which is determined after trapping. The efficiency of recovery is 96-99% for FeS(amorph), 76-88% for FeS(min), and >97% for FeS(2min). This method has a high reproducibility if the experimental conditions are rigorously applied and only glass conduits are used. A well ventilated fume hood must be used because of the toxicity and volatility of several reagents and products. The advantage relative to previously described methods are better resolution for iron sulfide species and use of the same bottles for both incubation of cultures and acid degradation. The method can also be used for Fe/S stoichiometry with sub-sampling and Fe analysis.

Rotary drum composting of vegetable waste and tree leaves.

PubMed

Kalamdhad, Ajay S; Singh, Yatish K; Ali, Muntjeer; Khwairakpam, Meena; Kazmi, A A

2009-12-01

High rate composting studies on institutional waste, i.e. vegetable wastes, tree leaves, etc., were conducted on a demonstration-scale (3.5 m(3)) rotary drum composter by evaluating changes in some physico-chemical and biological parameters. During composting, higher temperature (60-70 degrees C) at inlet zone and (50-60 degrees C) at middle zone were achieved which resulted in high degradation in the drum. As a result, all parameters including TOC, C/N ratio, CO(2) evolution and coliforms were decreased significantly within few days of composting. Within a week period, quality compost with total nitrogen (2.6%) and final total phosphorus (6 g/kg) was achieved; but relatively higher final values of fecal coliforms and CO(2) evolution, suggested further maturation. Thus, two conventional composting methods namely windrow (M1) and vermicomposting (M2) tried for maturation of primary stabilized compost. By examining these methods, it was suggested that M2 was found suitable in delivering fine grained, better quality matured compost within 20 days of maturation period.

Stereoselective Behavior of the Chiral Herbicides Diclofop-Methyl and Diclofop During the Soy Sauce Brewing Process.

PubMed

Lu, Yuele; Zhang, Dong; Liao, Yahui; Diao, Jinling; Chen, Xiaolong

2016-01-01

Chiral pesticides are now receiving more and more attention in the food-making process. This experiment studied the enantioselective behavior of diclofop-methyl (DM) and its main metabolite, diclofop (DC), during the soy sauce brewing process. Two kinds of commonly used strains, Aspergillus oryzae and Saccharomyces rouxii, were investigated. However, they showed a different degradation ability to the enantiomers of DM and DC. It was observed that (-)-(S)-DM was degraded much faster than (+)-(R)-DM by Saccharomyces rouxii, while no stereoselective degradation was found by Aspergillus oryzae. DC represented a relatively long residue period in this fermentation process and both strains showed a weak degradation ability to DC, especially Saccharomyces rouxii. There was little DC detected in the final product, while most of the DC residues persisted in the lees, which were usually used as animal feeds or discarded into the environment directly as waste. Therefore, more attention should be paid to the soy sauce brewing process concerning pesticide residues both in the final product and byproducts. © 2015 Wiley Periodicals, Inc.

Abiotic, biotic and photolytic degradation affinity of 14 antibiotics and one metabolite - batch experiments and a model framework.

PubMed

Kaeseberg, Thomas; Zhang, Jin; Schubert, Sara; Oertel, Reinhard; Krebs, Peter

2018-05-26

In this study, degradation affinities of 14 antibiotics and one metabolite were determined in batch experiments. A modelling framework was applied to decrypt potential ranges of abiotic, biotic and photolytic degradation coefficients. In detail, we performed batch experiments with three different sewages in the dark at 7 °C and 22 °C. Additionally, we conducted further batch experiments with artificial irradiation and different dilutions of the sewage at 30 °C - de novo three different sewages were used. The batch experiments were initially spiked with a stock solution with 14 antibiotics and one metabolite to increase background concentrations by 1 μg L -1 for each compound. The final antibiotic concentrations were sub-inhibitory with regard to sewage bacteria. The here presented modelling framework based on the Activated Sludge Model No. 3 in combination with adsorption and desorption processes. The model was calibrated with monitored standard sewage compounds before antibiotic degradation rates were quantified. The model decrypted ranges of abiotic, biotic and photolytic degradation coefficients. In detail, six antibiotics were not abiotic degradable at 7 °C, five antibiotics not at 22 °C and only 2 antibiotics at 30 °C. Finally, nine antibiotics were not significantly biodegradable at 7 °C and 22 °C. The model determined the link between adsorption characteristics and biodegradation rates. In detail, the rate was significantly affected by the bio-solid partition coefficient and the duration until adsorption was balanced. All antibiotics and the metabolite were photolytic degradable. In general, photolytic degradation was the most efficient elimination pathway of presented antibiotics except for the given metabolite and penicillin antibiotics. Copyright © 2018 Elsevier Ltd. All rights reserved.

Weak fault detection and health degradation monitoring using customized standard multiwavelets

NASA Astrophysics Data System (ADS)

Yuan, Jing; Wang, Yu; Peng, Yizhen; Wei, Chenjun

2017-09-01

Due to the nonobvious symptoms contaminated by a large amount of background noise, it is challenging to beforehand detect and predictively monitor the weak faults for machinery security assurance. Multiwavelets can act as adaptive non-stationary signal processing tools, potentially viable for weak fault diagnosis. However, the signal-based multiwavelets suffer from such problems as the imperfect properties missing the crucial orthogonality, the decomposition distortion impossibly reflecting the relationships between the faults and signatures, the single objective optimization and independence for fault prognostic. Thus, customized standard multiwavelets are proposed for weak fault detection and health degradation monitoring, especially the weak fault signature quantitative identification. First, the flexible standard multiwavelets are designed using the construction method derived from scalar wavelets, seizing the desired properties for accurate detection of weak faults and avoiding the distortion issue for feature quantitative identification. Second, the multi-objective optimization combined three dimensionless indicators of the normalized energy entropy, normalized singular entropy and kurtosis index is introduced to the evaluation criterions, and benefits for selecting the potential best basis functions for weak faults without the influence of the variable working condition. Third, an ensemble health indicator fused by the kurtosis index, impulse index and clearance index of the original signal along with the normalized energy entropy and normalized singular entropy by the customized standard multiwavelets is achieved using Mahalanobis distance to continuously monitor the health condition and track the performance degradation. Finally, three experimental case studies are implemented to demonstrate the feasibility and effectiveness of the proposed method. The results show that the proposed method can quantitatively identify the fault signature of a slight rub on the inner race of a locomotive bearing, effectively detect and locate the potential failure from a complicated epicyclic gear train and successfully reveal the fault development and performance degradation of a test bearing in the lifetime.

Resource recovery of food waste through continuous thermophilic in-vessel composting.

PubMed

Waqas, Mohammad; Almeelbi, Talal; Nizami, Abdul-Sattar

2018-02-01

In the Kingdom of Saudi Arabia (KSA) and Gulf region, a very small amount of municipal solid waste (MSW) is treated for compost production. The produced compost through traditional methods of compost piles and trenches does not coincide with the international standards of compost quality. Therefore, in this study, a continuous thermophilic composting (CTC) method is introduced as a novel and efficient technique for treating food waste into a quality compost in a short period of time. The quality of the compost was examined by degradation rates of organic matter (OM), changes in total carbon (TC), ash contents, pH, dynamics in ammonium nitrogen (NH 4 -N) and nitrate nitrogen (NO 3 -N), and nitrification index (NI). The results showed that thermophilic treatment at 60 °C increased the pH of the substrate and promoted degradation and mineralization process. After 30 days of composting, the degree of OM degradation was increased by 43.26 and 19.66%, NH 4 -N by 65.22 and 25.23%, and NO 3 -N by 44.76 and 40.05% as compared to runs treated at 25 and 40 °C, respectively. The stability of the compost was attained after 30 to 45 days with quality better than the compost that was stabilized after 60 days of the experiment under mesophilic treatment (25 °C). The final compost also showed stability at room temperature, confirming the rapid degradation and maturation of food waste after thermophilic treatment. Moreover, the quality of produced compost is in line with the compost quality standard of United States (US), California, Germany, and Austria. Hence, CTC can be implemented as a novel method for rapid decomposition of food waste into a stable organic fertilizer in the given hot climatic conditions of KSA and other Gulf countries with a total net saving of around US $70.72 million per year.

Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

NASA Astrophysics Data System (ADS)

Adenrele Adeniyi, Sunday; de Clercq, Willem Petrus; van Niekerk, Adriaan

2017-08-01

Cocoa agroecosystems are a major land-use type in the tropical rainforest belt of West Africa, reportedly associated with several ecological changes, including soil degradation. This study aims to develop a composite soil degradation assessment index (CSDI) for determining the degradation level of cocoa soils under smallholder agroecosystems of southwestern Nigeria. Plots where natural forests have been converted to cocoa agroecosystems of ages 1-10, 11-40, and 41-80 years, respectively representing young cocoa plantations (YCPs), mature cocoa plantations (MCPs), and senescent cocoa plantations (SCPs), were identified to represent the biological cycle of the cocoa tree. Soil samples were collected at a depth of 0 to 20 cm in each plot and analysed in terms of their physical, chemical, and biological properties. Factor analysis of soil data revealed four major interacting soil degradation processes: decline in soil nutrients, loss of soil organic matter, increase in soil acidity, and the breakdown of soil textural characteristics over time. These processes were represented by eight soil properties (extractable zinc, silt, soil organic matter (SOM), cation exchange capacity (CEC), available phosphorus, total porosity, pH, and clay content). These soil properties were subjected to forward stepwise discriminant analysis (STEPDA), and the result showed that four soil properties (extractable zinc, cation exchange capacity, SOM, and clay content) are the most useful in separating the studied soils into YCP, MCP, and SCP. In this way, we have sufficiently eliminated redundancy in the final selection of soil degradation indicators. Based on these four soil parameters, a CSDI was developed and used to classify selected cocoa soils into three different classes of degradation. The results revealed that 65 % of the selected cocoa farms are moderately degraded, while 18 % have a high degradation status. The numerical value of the CSDI as an objective index of soil degradation under cocoa agroecosystems was statistically validated. The results of this study reveal that soil management should promote activities that help to increase organic matter and reduce Zn deficiency over the cocoa growth cycle. Finally, the newly developed CSDI can provide an early warning of soil degradation processes and help farmers and extension officers to implement rehabilitation practices on degraded cocoa soils.

Kinetic modeling and determination role of sono/photo nanocatalyst-generated radical species on degradation of hydroquinone in aqueous solution.

PubMed

Rahimi, Sajad; Ayati, Bita; Rezaee, Abbas

2016-06-01

Experimental findings of sonophotocatalytic process were used in degradation of hydroquinone to assess kinetic modeling and determine the effect of various active radical species. First, the effects of three photocatalytic, sonocatalytic, and sonophotocatalytic processes were studied for hydroquinone removal to determine kinetic constants and calculate the activation energy of reactions, and then the selected process was evaluated to determine active radical species. The reactor was composed of two parts, one included ultrasonic probe (sonocatalytic part) with powers 22, 80, and 176 W and the second part was the location of UV lamp (photocatalytic part) with tubular flow and power 15 W. After three systems were examined and the efficient system was selected, the role of different active species such as hydroxyl radical (OH(·)), superoxide radical (O2 (·-)), hole (h(+)), electrons (e (-)), and single oxygen molecule ((1)O2) and contribution of each of them were determined in hydroquinone degradation. According to tests, the results of this study showed that sonophotocatalytic integrated method as selected system among three systems studied followed the first-order equation for hydroquinone degradation and active hydroxyl species with 45 % and electron and hole with 15 and 10 %, respectively, had the highest and lowest contributions to conversion of hydroquinone. The findings showed that dissolved oxygen increases the capability of active radical formation so that 28.2 % of hydroquinone removal was increased under aeration compared to without aeration. Also, removal efficiency decreased 62 % with N2 injection due to the withdrawal of oxygen from the sample. By adding 25 Mm of sodium azide (NaN3) to stock solution, 46.5 % reduction was developed because single oxygen ((1)O2) played the role of an active species. The advantages of integrated sonocatalytic and photocatalytic method are the generation of active radical species with more variety and ultimately the formation of higher amounts of powerful hydroxyl radical that increases degradation rates of refractory compounds and low-risk internal and final products. It has an appropriate performance in the degradation of refractory compounds by optimizing effective operational factors.

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.

Degradation of triclosan and its main intermediates during the combined irradiation and biological treatment.

PubMed

Wang, Shizong; Wang, Jianlong

2018-05-01

Triclosan is an extensively applied antimicrobial agent which has been frequently detected in the environment. In this paper, the degradation of triclosan and its main intermediates was investigated during the combined irradiation and biological treatment. The results showed that triclosan degradation increased with increase of absorbed dose, the removal efficiency of triclosan was 62%, 77%, 87%, 91% and 94%, respectively at 1, 2, 3, 4 and 5 kGy. The final removal efficiency of triclosan after the combined irradiation and biological process was 81%, 86%, 90%, 92% and 95%, respectively. During the irradiation process, two main intermediates, that is, 4,4'-2'-phenoxyphenol (Intermediate 1) and 4-chloro-2'-phenoxyphenol (Intermediate 2) were detected, in which Intermediate 1 dominated during the irradiation process. In the following biological treatment process, Intermediates 1 and 2 could be further degraded. In single biological treatment process, the final removal efficiency of triclosan was 54%, and Intermediates 1 and 2 were detected. Intermediate 1 could be biodegraded while Intermediate 2 could not. The concentration of Intermediate 2 increased during biological treatment process. In conclusion, irradiation as pre-treatment process can enhance the degradation of triclosan and improve the biodegradability of Intermediate 2. Combined irradiation and biological process can be promising for treating antibiotic-containing wastewater.

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses.

PubMed

Boyd, Thomas J; Montgomery, Michael T; Cuenca, Richard H; Hagimoto, Yutaka

2016-10-21

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal - or rather the absence of signal - is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14 C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually <30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making.

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

PubMed Central

Boyd, Thomas J.; Montgomery, Michael T.; Cuenca, Richard H.; Hagimoto, Yutaka

2016-01-01

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal — or rather the absence of signal — is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually <30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making. PMID:27805601

Robust PV Degradation Methodology and Application

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

Jordan, Dirk; Deline, Christopher A; Kurtz, Sarah

The degradation rate plays an important role in predicting and assessing the long-term energy generation of PV systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this manuscript, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year (YOY) rate calculation. We show the method to provide reliable degradation rate estimates even in the case ofmore » sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.« less

Robust PV Degradation Methodology and Application

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

Jordan, Dirk C.; Deline, Chris; Kurtz, Sarah R.

The degradation rate plays an important role in predicting and assessing the long-term energy generation of photovoltaics (PV) systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this paper, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year rate calculation. We show the method to provide reliable degradation rate estimates even in the case ofmore » sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.« less

Robust PV Degradation Methodology and Application

DOE PAGES

Jordan, Dirk C.; Deline, Chris; Kurtz, Sarah R.; ...

2017-12-21

The degradation rate plays an important role in predicting and assessing the long-term energy generation of photovoltaics (PV) systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this paper, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year rate calculation. We show the method to provide reliable degradation rate estimates even in the case ofmore » sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.« less

Recovering of images degraded by atmosphere

NASA Astrophysics Data System (ADS)

Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

2017-08-01

Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

Method of radiation degradation of PTFE under vacuum conditions

NASA Astrophysics Data System (ADS)

Korenev, Sergey

2004-09-01

A new method of radiation degradation of Polytetrafluoroethylene (PTFE) under vacuum conditions is considered in this report. The combination of glow gas discharge and electrical surface discharge (on surface and inside PTFE) increases the efficiency of thermal-radiation degradation. The main mechanism of this degradation method consists of the breaking of C-C and C-F bonds. The vacuum conditions allow decreasing of the concentration of toxic compounds, such as a HF. Experimental results for degradation of PTFE are presented.

Effect of inoculation with white-rot fungi and fungal consortium on the composting efficiency of municipal solid waste.

PubMed

Voběrková, Stanislava; Vaverková, Magdalena D; Burešová, Alena; Adamcová, Dana; Vršanská, Martina; Kynický, Jindřich; Brtnický, Martin; Adam, Vojtěch

2017-03-01

An investigation was carried out on the effect of inoculation methods on the compost of an organic fraction of municipal solid waste. Three types of white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor and Fomes fomentarius), and a consortium of these fungi, were used. The study assessed their influence on microbial enzymatic activities and the quality of the finished compost. It was found that the addition of white-rot fungi to municipal solid waste (after 37days of composting) could be a useful strategy for enhancing the properties of the final compost product. In comparison with the control sample (compost without inoculation), it accelerates degradation of solid waste as indicated by changes in C/N, electrical conductivity and pH. However, the effectiveness of waste degradation and compost maturation depends on the type of microorganism used for inoculation. The presence of inoculants, such as Trametes versicolor and Fomes fomentarius, led to a higher degrading ratio and a better degree of maturity. This resulted in an increase of enzymatic activities (especially dehydrogenase and protease) and a germination index in comparison with inoculation using Phanerochaete chrysosporium or a consortium of fungi. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Mg doping on ZnO nanoparticles decorated on graphene oxide (GO) crumpled paper like sheet and its high photo catalytic performance under sunlight

NASA Astrophysics Data System (ADS)

Labhane, P. K.; Sonawane, S. H.; Sonawane, G. H.; Patil, S. P.; Huse, V. R.

2018-03-01

Mg doped ZnO nanoparticles decorated on graphene oxide (GO) sheets were synthesized by a wet impregnation method. The effect of Mg doping on ZnO and ZnO-GO composite has been evaluated by using x-ray diffraction (XRD), Williamson-Hall Plot (Wsbnd H Plot), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDX). The physical parameters of as-prepared samples were estimated by XRD data. FESEM and HR-TEM images showed the uniform distribution of nanoparticles on GO crumpled paper like sheet. Solar light photocatalytic activities of samples were evaluated spectrophotometrically by the degradation of p-nitrophenol (PNP) and indigo carmine (IC) solution. Mgsbnd ZnO decorated on GO sheets exhibit excellent catalytic efficiency compared to all other prepared samples under identical conditions, degrading PNP and IC nearly 99% within 60 min under sunlight. The effective degradation by Mgsbnd ZnO decorated on GO sheet would be due to extended solar light absorption, enhanced adsorptivity on the composite catalyst surface and efficient charge separation of photo-induced electrons. Finally, plausible mechanism was suggested with the help of scavengers study.

Optimal Information Extraction of Laser Scanning Dataset by Scale-Adaptive Reduction

NASA Astrophysics Data System (ADS)

Zang, Y.; Yang, B.

2018-04-01

3D laser technology is widely used to collocate the surface information of object. For various applications, we need to extract a good perceptual quality point cloud from the scanned points. To solve the problem, most of existing methods extract important points based on a fixed scale. However, geometric features of 3D object come from various geometric scales. We propose a multi-scale construction method based on radial basis function. For each scale, important points are extracted from the point cloud based on their importance. We apply a perception metric Just-Noticeable-Difference to measure degradation of each geometric scale. Finally, scale-adaptive optimal information extraction is realized. Experiments are undertaken to evaluate the effective of the proposed method, suggesting a reliable solution for optimal information extraction of object.

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.

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.

High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR).

PubMed

Wang, Ruijia; Chen, Jie; Wang, Xing; Sun, Bing

2017-01-09

Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method.

High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR)

PubMed Central

Wang, Ruijia; Chen, Jie; Wang, Xing; Sun, Bing

2017-01-01

Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method. PMID:28075367

Controlling release from 3D printed medical devices using CLIP and drug-loaded liquid resins.

PubMed

Bloomquist, Cameron J; Mecham, Michael B; Paradzinsky, Mark D; Janusziewicz, Rima; Warner, Samuel B; Luft, J Christopher; Mecham, Sue J; Wang, Andrew Z; DeSimone, Joseph M

2018-05-28

Mass customization along with the ability to generate designs using medical imaging data makes 3D printing an attractive method for the fabrication of patient-tailored drug and medical devices. Herein we describe the application of Continuous Liquid Interface Production (CLIP) as a method to fabricate biocompatible and drug-loaded devices with controlled release properties, using liquid resins containing active pharmaceutical ingredients (API). In this work, we characterize how the release kinetics of a model small molecule, rhodamine B-base (RhB), are affected by device geometry, network crosslink density, and the polymer composition of polycaprolactone- and poly (ethylene glycol)-based networks. To demonstrate the applicability of using API-loaded liquid resins with CLIP, the UV stability was evaluated for a panel of clinically-relevant small molecule drugs. Finally, select formulations were tested for biocompatibility, degradation and encapsulation of docetaxel (DTXL) and dexamethasone-acetate (DexAc). Formulations were shown to be biocompatible over the course of 175 days of in vitro degradation and the clinically-relevant drugs could be encapsulated and released in a controlled fashion. This study reveals the potential of the CLIP manufacturing platform to serve as a method for the fabrication of patient-specific medical and drug-delivery devices for personalized medicine. Copyright © 2018. Published by Elsevier B.V.

Enhanced Photocatalytic Activity toward Organic Pollutants Degradation and Mechanism Insight of Novel CQDs/Bi₂O₂CO₃ Composite.

PubMed

Zhang, Zisheng; Lin, Shuanglong; Li, Xingang; Li, Hong; Zhang, Tong; Cui, Wenquan

2018-05-15

Novel carbon quantum dots (CQDs) modified with Bi₂O₂CO₃ (CQDs/Bi₂O₂CO₃) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were used to test the material composition, structure, and band structures of the as-prepared samples. Methylene blue (MB) and colorless phenol, as target organic pollutants, were used to evaluate the photocatalytic performance of the CQDs/Bi₂O₂CO₃ hybrid materials under visible light irradiation. Experimental investigation shows that 2⁻5 nm CQDs were uniformly decorated on the surface of Bi₂O₂CO₃; CQDs/Bi₂O₂CO₃ possess an efficient photocatalytic performance, and the organic matter removal rate of methylene blue and phenol can reach up to 94.45% and 61.46% respectively, within 2 h. In addition, the degradation analysis of phenol by high performance liquid chromatography (HPLC) proved that there are no other impurities in the degradation process. Photoelectrochemical testing proved that the introduction of CQDs (electron acceptor) effectively suppresses the recombination of e - -h⁺, and promotes charge transfer. Quenching experiments and electron spin resonance (ESR) suggested that ·OH, h⁺, and ·O₂ - were involved in the photocatalytic degradation process. These results suggested that the up-conversion function of CQDs could improve the electron transfer and light absorption ability of photocatalysts and ·O₂ - formation. Furthermore, the up-conversion function of CQDs would help maintain photocatalytic stability. Finally, the photocatalytic degradation mechanism was proposed according to the above experimental result.

Highly ordered Fe3+/TiO2 nanotube arrays for efficient photocataltyic degradation of nitrobenzene

NASA Astrophysics Data System (ADS)

Zhang, Yiyang; Gu, Di; Zhu, Lingyue; Wang, Baohui

2017-10-01

Highly ordered TiO2 nanotube arrays (TiO2 NTs) were prepared through a facile two-step electrochemical anodization, subsequently, active iron ions were introduced into the TiO2 NTs via a direct impregnation method. The XPS results showed that the iron elements existed in TiO2 NTs in the form of Fe3+ ions. Compared with the undoped TiO2 NTs, the absorption edge of Fe3+/TiO2 NTs showed an overt red shift and the photocurrent improved obviously, which indicated that Fe3+/TiO2 had a much higher photocatalytic activity. The optimal doping content was tested to be 0.1 mol/L which could make the photocatalytic activity of TiO2 NTs obviously improves under both visible and ultraviolent light. The prepared samples were adopted as photocatalyst to degrade nitrobenzene (NB). The reaction rate constants ks under UV light were in the order kone-stepTiO2NTs = 0.00338

Characterization of the biodegradation, bioremediation and detoxification capacity of a bacterial consortium able to degrade the fungicide thiabendazole.

PubMed

Perruchon, Chiara; Pantoleon, Anastasios; Veroutis, Dimitrios; Gallego-Blanco, Sara; Martin-Laurent, F; Liadaki, Kalliopi; Karpouzas, Dimitrios G

2017-12-01

Thiabendazole (TBZ) is a persistent fungicide used in the post-harvest treatment of fruits. Its application results in the production of contaminated effluents which should be treated before their environmental discharge. In the absence of efficient treatment methods in place, biological systems based on microbial inocula with specialized degrading capacities against TBZ could be a feasible treatment approach. Only recently the first bacterial consortium able to rapidly transform TBZ was isolated. This study aimed to characterize its biodegradation, bioremediation and detoxification potential. The capacity of the consortium to mineralize 14 C-benzyl-ring labelled TBZ was initially assessed. Subsequent tests evaluated its degradation capacity under various conditions (range of pH, temperatures and TBZ concentration levels) and relevant practical scenarios (simultaneous presence of other postharvest compounds) and its bioaugmentation potential in soils contaminated with increasing TBZ levels. Finally cytotoxicity assays explored its detoxification potential. The consortium effectively mineralized the benzoyl ring of the benzimidazole moiety of TBZ and degraded spillage level concentrations of the fungicide in aqueous cultures (750 mg L -1 ) and in soil (500 mg kg -1 ). It maintained its high degradation capacity in a wide range of pH (4.5-7.5) and temperatures (15-37 °C) and in the presence of other pesticides (ortho-phenylphenol and diphenylamine). Toxicity assays using the human liver cancer cell line HepG2 showed a progressive decrease in cytotoxicity, concomitantly with the biodegradation of TBZ, pointing to a detoxification process. Overall, the bacterial consortium showed high potential for future implementation in bioremediation and biodepuration applications.

A method for scintillation characterization using geodetic receivers operating at 1 Hz

NASA Astrophysics Data System (ADS)

Juan, J. M.; Aragon-Angel, A.; Sanz, J.; González-Casado, G.; Rovira-Garcia, A.

2017-11-01

Ionospheric scintillation produces strong disruptive effects on global navigation satellite system (GNSS) signals, ranging from degrading performances to rendering these signals useless for accurate navigation. The current paper presents a novel approach to detect scintillation on the GNSS signals based on its effect on the ionospheric-free combination of carrier phases, i.e. the standard combination of measurements used in precise point positioning (PPP). The method is implemented using actual data, thereby having both its feasibility and its usefulness assessed at the same time. The results identify the main effects of scintillation, which consist of an increased level of noise in the ionospheric-free combination of measurements and the introduction of cycle-slips into the signals. Also discussed is how mis-detected cycle-slips contaminate the rate of change of the total electron content index (ROTI) values, which is especially important for low-latitude receivers. By considering the effect of single jumps in the individual frequencies, the proposed method is able to isolate, over the combined signal, the frequency experiencing the cycle-slip. Moreover, because of the use of the ionospheric-free combination, the method captures the diffractive nature of the scintillation phenomena that, in the end, is the relevant effect on PPP. Finally, a new scintillation index is introduced that is associated with the degradation of the performance in navigation.

Near-infrared spectroscopic observation of the ageing process in archaeological wood using a deuterium exchange method.

PubMed

Tsuchikawa, Satoru; Yonenobu, Hitoshi; Siesler, H W

2005-03-01

The ageing degradation of the fine wood structure of dry-exposed archaeological wood was investigated by Fourier transform near-infrared spectroscopy with the aid of a deuterium exchange method. The archaeological wood sample was taken from an old wooden temple in Japan (late 7th century), which has been designated as a UNESCO world heritage site. Comparing the analytical results with those of a modern wood sample of the same species, the ageing process of archaeological wood was clarified as a change in the state of order on a macromolecular structural level. It can be concluded from NIR spectra that the amorphous region, and partially semi-crystalline region, in cellulose, hemicellulose, and lignin decreased by the ageing degradation, whereas the crystalline region in cellulose was not affected by the ageing. The accessibility of the diffusant to effect H/D-exchange was monitored by an OH-related absorption band obtained from FT-NIR transmission spectroscopy and characteristically varied with the ageing process of the wood samples, the absorption bands characteristic of a specific state of order and the diffusion agent. Finally, we proposed a morphological model to describe the variation of the fine structure of the microfibrils in the cell wall with ageing degradation. The state of microfibrils changed loosely by ageing, so that elementary fibrils were arranged loosely under 5 A, whereas several elementary fibrils in the modern wood were arranged in very close proximity under 3 A to each other.

The different roles of selective autophagic protein degradation in mammalian cells.

PubMed

Wang, Da-wei; Peng, Zhen-ju; Ren, Guang-fang; Wang, Guang-xin

2015-11-10

Autophagy is an intracellular pathway for bulk protein degradation and the removal of damaged organelles by lysosomes. Autophagy was previously thought to be unselective; however, studies have increasingly confirmed that autophagy-mediated protein degradation is highly regulated. Abnormal autophagic protein degradation has been associated with multiple human diseases such as cancer, neurological disability and cardiovascular disease; therefore, further elucidation of protein degradation by autophagy may be beneficial for protein-based clinical therapies. Macroautophagy and chaperone-mediated autophagy (CMA) can both participate in selective protein degradation in mammalian cells, but the process is quite different in each case. Here, we summarize the various types of macroautophagy and CMA involved in determining protein degradation. For this summary, we divide the autophagic protein degradation pathways into four categories: the post-translational modification dependent and independent CMA pathways and the ubiquitin dependent and independent macroautophagy pathways, and describe how some non-canonical pathways and modifications such as phosphorylation, acetylation and arginylation can influence protein degradation by the autophagy lysosome system (ALS). Finally, we comment on why autophagy can serve as either diagnostics or therapeutic targets in different human diseases.

Degradation of oxcarbazepine by UV-activated persulfate oxidation: kinetics, mechanisms, and pathways.

PubMed

Bu, Lingjun; Zhou, Shiqing; Shi, Zhou; Deng, Lin; Li, Guangchao; Yi, Qihang; Gao, Naiyun

2016-02-01

The degradation kinetics and mechanism of the antiepileptic drug oxcarbazepine (OXC) by UV-activated persulfate oxidation were investigated in this study. Results showed that UV/persulfate (UV/PS) process appeared to be more effective in degrading OXC than UV or PS alone. The OXC degradation exhibited a pseudo-first order kinetics pattern and the degradation rate constants (k obs) were affected by initial OXC concentration, PS dosage, initial pH, and humic acid concentration to different degrees. It was found that low initial OXC concentration, high persulfate dosage, and initial pH enhanced the OXC degradation. Additionally, the presence of humic acid in the solution could greatly inhibit the degradation of OXC. Moreover, hydroxyl radical (OH•) and sulfate radical (SO4 (-)••) were identified to be responsible for OXC degradation and SO4 (-)• made the predominant contribution in this study. Finally, major intermediate products were identified and a preliminary degradation pathway was proposed. Results demonstrated that UV/PS system is a potential technology to control the water pollution caused by emerging contaminants such as OXC.

Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Naphthalene-Degrading Comamonas sp. JB.

PubMed

Ji, Xiangyu; Xu, Jing; Ning, Shuxiang; Li, Nan; Tan, Liang; Shi, Shengnan

2017-12-01

Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

Plant secondary metabolite-induced shifts in bacterial community structure and degradative ability in contaminated soil.

PubMed

Uhlik, Ondrej; Musilova, Lucie; Ridl, Jakub; Hroudova, Miluse; Vlcek, Cestmir; Koubek, Jiri; Holeckova, Marcela; Mackova, Martina; Macek, Tomas

2013-10-01

The aim of the study was to investigate how selected natural compounds (naringin, caffeic acid, and limonene) induce shifts in both bacterial community structure and degradative activity in long-term polychlorinated biphenyl (PCB)-contaminated soil and how these changes correlate with changes in chlorobiphenyl degradation capacity. In order to address this issue, we have integrated analytical methods of determining PCB degradation with pyrosequencing of 16S rRNA gene tag-encoded amplicons and DNA-stable isotope probing (SIP). Our model system was set in laboratory microcosms with PCB-contaminated soil, which was enriched for 8 weeks with the suspensions of flavonoid naringin, terpene limonene, and phenolic caffeic acid. Our results show that application of selected plant secondary metabolites resulted in bacterial community structure far different from the control one (no natural compound amendment). The community in soil treated with caffeic acid is almost solely represented by Proteobacteria, Acidobacteria, and Verrucomicrobia (together over 99 %). Treatment with naringin resulted in an enrichment of Firmicutes to the exclusion of Acidobacteria and Verrucomicrobia. SIP was applied in order to identify populations actively participating in 4-chlorobiphenyl catabolism. We observed that naringin and limonene in soil foster mainly populations of Hydrogenophaga spp., caffeic acid Burkholderia spp. and Pseudoxanthomonas spp. None of these populations were detected among 4-chlorobiphenyl utilizers in non-amended soil. Similarly, the degradation of individual PCB congeners was influenced by the addition of different plant compounds. Residual content of PCBs was lowest after treating the soil with naringin. Addition of caffeic acid resulted in comparable decrease of total PCBs with non-amended soil; however, higher substituted congeners were more degraded after caffeic acid treatment compared to all other treatments. Finally, it appears that plant secondary metabolites have a strong effect on the bacterial community structure, activity, and associated degradative ability.

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.

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

Changes in the performance characteristics of a GaAs near infrared light emitting diode when exposed to various current and thermal stresses

NASA Technical Reports Server (NTRS)

Thomas, E. F., Jr.

1974-01-01

The changes that occurred in the optical and electrical characteristics of a near infrared, GaAs light emitting diode, when operated under various levels and combinations of current and thermal stresses are discussed. A total of forty parts were operated for two thousand hours under eight different sets of dc current and ambient temperature conditions. Degradation in the radiant optical power of these devices was thirty-four percent when operated at their rated current and an ambient temperature of 298K (25 C). Derating the current and/or the thermal stress reduced the degradation of this parameter in approximately a linear manner. All degraded devices behaved similarly, exhibiting rapid nonlinear degradation followed by a gradual linear degradation and finally a period of stable operation. An attempt was made to correlate initial device condition to degradation during stress testing, but met with little success.

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.

Anaerobic biodegradation of BTEX using Mn(IV) and Fe(III) as alternative electron acceptors.

PubMed

Villatoro-Monzón, W R; Mesta-Howard, A M; Razo-Flores, E

2003-01-01

Anaerobic BTEX biodegradation was tested in batch experiments using an anaerobic sediment as inoculum under Fe(III) and Mn(IV) reducing conditions. All BTEX were degraded under the conditions tested, specially under Mn(IV) reducing conditions, where benzene was degraded at a rate of 0.8 micromol l(-1) d(-1), significantly much faster than Fe(III) reducing conditions. Under Fe(III) reducing conditions, ethylbenzene was the compound that degraded at the faster rate of 0.19 micromol l(-1) d(-1). Mn(IV) reducing conditions are energetically more favourable than Fe(III), therefore, BTEX were more rapidly degraded under Mn(IV) reducing conditions. These results represent the first report of the degradation of benzene with Mn(IV) as the final electron acceptor. Amorphous manganese oxide is a natural widely distributed metal in groundwater, where it can be microbiologically reduced, leading to the degradation of monoaromatic compounds.

Cdt2-mediated XPG degradation promotes gap-filling DNA synthesis in nucleotide excision repair

PubMed Central

Han, Chunhua; Wani, Gulzar; Zhao, Ran; Qian, Jiang; Sharma, Nidhi; He, Jinshan; Zhu, Qianzheng; Wang, Qi-En; Wani, Altaf A

2015-01-01

Xeroderma pigmentosum group G (XPG) protein is a structure-specific repair endonuclease, which cleaves DNA strands on the 3′ side of the DNA damage during nucleotide excision repair (NER). XPG also plays a crucial role in initiating DNA repair synthesis through recruitment of PCNA to the repair sites. However, the fate of XPG protein subsequent to the excision of DNA damage has remained unresolved. Here, we show that XPG, following its action on bulky lesions resulting from exposures to UV irradiation and cisplatin, is subjected to proteasome-mediated proteolytic degradation. Productive NER processing is required for XPG degradation as both UV and cisplatin treatment-induced XPG degradation is compromised in NER-deficient XP-A, XP-B, XP-C, and XP-F cells. In addition, the NER-related XPG degradation requires Cdt2, a component of an E3 ubiquitin ligase, CRL4Cdt2. Micropore local UV irradiation and in situ Proximity Ligation assays demonstrated that Cdt2 is recruited to the UV-damage sites and interacts with XPG in the presence of PCNA. Importantly, Cdt2-mediated XPG degradation is crucial to the subsequent recruitment of DNA polymerase δ and DNA repair synthesis. Collectively, our data support the idea of PCNA recruitment to damage sites which occurs in conjunction with XPG, recognition of the PCNA-bound XPG by CRL4Cdt2 for specific ubiquitylation and finally the protein degradation. In essence, XPG elimination from DNA damage sites clears the chromatin space needed for the subsequent recruitment of DNA polymerase δ to the damage site and completion of gap-filling DNA synthesis during the final stage of NER. PMID:25483071

Novel sample preparation method for surfactant containing suppositories: effect of micelle formation on drug recovery.

PubMed

Kalmár, Éva; Ueno, Konomi; Forgó, Péter; Szakonyi, Gerda; Dombi, György

2013-09-01

Rectal drug delivery is currently at the focus of attention. Surfactants promote drug release from the suppository bases and enhance the formulation properties. The aim of our work was to develop a sample preparation method for HPLC analysis for a suppository base containing 95% hard fat, 2.5% Tween 20 and 2.5% Tween 60. A conventional sample preparation method did not provide successful results as the recovery of the drug failed to fulfil the validation criterion 95-105%. This was caused by the non-ionic surfactants in the suppository base incorporating some of the drug, preventing its release. As guidance for the formulation from an analytical aspect, we suggest a well defined surfactant content based on the turbidimetric determination of the CMC (critical micelle formation concentration) in the applied methanol-water solvent. Our CMC data correlate well with the results of previous studies. As regards the sample preparation procedure, a study was performed of the effects of ionic strength and pH on the drug recovery with the avoidance of degradation of the drug during the procedure. Aminophenazone and paracetamol were used as model drugs. The optimum conditions for drug release from the molten suppository base were found to be 100 mM NaCl, 20-40 mM NaOH and a 30 min ultrasonic treatment of the final sample solution. As these conditions could cause the degradation of the drugs in the solution, this was followed by NMR spectroscopy, and the results indicated that degradation did not take place. The determined CMCs were 0.08 mM for Tween 20, 0.06 mM for Tween 60 and 0.04 mM for a combined Tween 20, Tween 60 system. Copyright © 2013 Elsevier B.V. All rights reserved.

Time-Variant Reliability Analysis for Rubber O-Ring Seal Considering Both Material Degradation and Random Load

PubMed Central

Liao, Baopeng; Yan, Meichen; Zhang, Weifang; Zhou, Kun

2017-01-01

Due to the increase in working hours, the reliability of rubber O-ring seals used in hydraulic systems of transfer machines will change. While traditional methods can only analyze one of the material properties or seal properties, the failure of the O-ring is caused by these two factors together. In this paper, two factors are mainly analyzed: the degradation of material properties and load randomization by processing technology. Firstly, the two factors are defined in terms of material failure and seal failure, before the experimental methods of rubber materials are studied. Following this, the time-variant material properties through experiments and load distribution by monitoring the processing can be obtained. Thirdly, compressive stress and contact stress have been calculated, which was combined with the reliability model to acquire the time-variant reliability for the O-ring. Finally, the life prediction and effect of oil pressure were discussed, then compared with the actual situation. The results show a lifetime of 12 months for the O-ring calculated in this paper, and compared with the replacement records from the maintenance workshop, the result is credible. PMID:29053597

Calculation methods to perform mass balances of micropollutants in sewage treatment plants. application to pharmaceutical and personal care products (PPCPs).

PubMed

Carballa, Marta; Omil, Francisco; Lema, Juan M

2007-02-01

Two different methods are proposed to perform the mass balance calculations of micropollutants in sewage treatment plants (STPs). The first method uses the measured data in both liquid and sludge phase and the second one uses the solid-water distribution coefficient (Kd) to calculate the concentrations in the sludge from those measured in the liquid phase. The proposed methodologies facilitate the identification of the main mechanisms involved in the elimination of micropollutants. Both methods are applied for determining mass balances of selected pharmaceutical and personal care products (PPCPs) and their results are discussed. In that way, the fate of 2 musks (galaxolide and tonalide), 3 pharmaceuticals (ibuprofen, naproxen, and sulfamethoxazole), and 2 natural estrogens (estrone and 17beta-estradiol) has been investigated along the different water and sludge treatment units of a STP. Ibuprofen, naproxen, and sulfamethoxazole are biologically degraded in the aeration tank (50-70%), while musks are equally sorbed to the sludge and degraded. In contrast, estrogens are not removed in the STP studied. About 40% of the initial load of pharmaceuticals passes through the plant unaltered, with the fraction associated to sludge lower than 0.5%. In contrast, between 20 and 40% of the initial load of musks leaves the plant associated to solids, with less than 10% present in the final effluent. The results obtained show that the conclusions concerning the efficiency of micropollutants removal in a particular STP may be seriously affected by the calculation method used.

Sequential deconvolution from wave-front sensing using bivariate simplex splines

NASA Astrophysics Data System (ADS)

Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Xu, Rong; Liu, Changhai

2015-05-01

Deconvolution from wave-front sensing (DWFS) is an imaging compensation technique for turbulence degraded images based on simultaneous recording of short exposure images and wave-front sensor data. This paper employs the multivariate splines method for the sequential DWFS: a bivariate simplex splines based average slopes measurement model is built firstly for Shack-Hartmann wave-front sensor; next, a well-conditioned least squares estimator for the spline coefficients is constructed using multiple Shack-Hartmann measurements; then, the distorted wave-front is uniquely determined by the estimated spline coefficients; the object image is finally obtained by non-blind deconvolution processing. Simulated experiments in different turbulence strength show that our method performs superior image restoration results and noise rejection capability especially when extracting the multidirectional phase derivatives.

Solar cell radiation handbook

NASA Technical Reports Server (NTRS)

Tada, H. Y.; Carter, J. R., Jr.

1977-01-01

Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

Vectorization of Nucleic Acids for Therapeutic Approach: Tutorial Review.

PubMed

Geinguenaud, Frederic; Guenin, Erwann; Lalatonne, Yoann; Motte, Laurence

2016-05-20

Oligonucleotides present a high therapeutic potential for a wide variety of diseases. However, their clinical development is limited by their degradation by nucleases and their poor blood circulation time. Depending on the administration mode and the cellular target, these macromolecules will have to cross the vascular endothelium, to diffuse through the extracellular matrix, to be transported through the cell membrane, and finally to reach the cytoplasm. To overcome these physiological barriers, many strategies have been developed. Here, we review different methods of DNA vectorization, discuss limitations and advantages of the various vectors, and provide new perspectives for future development.

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.

Final report for SERDP WP-2209 Replacement melt-castable formulations for Composition B

DTIC Science & Technology

2017-05-19

Chemical reaction of the materials in the melt ............................................................... 5 Thermal degradation of materials...reasons other than the hazard of explosion, these include: • Chemical reaction of the materials in the melt • Thermal degradation at low...temperature • Sublimation and condensation of explosive material on equipment and exposure to workers Chemical reaction of the materials in the melt

De novo prediction of the genomic components and capabilities for microbial plant biomass degradation from (meta-)genomes

PubMed Central

2013-01-01

Background Understanding the biological mechanisms used by microorganisms for plant biomass degradation is of considerable biotechnological interest. Despite of the growing number of sequenced (meta)genomes of plant biomass-degrading microbes, there is currently no technique for the systematic determination of the genomic components of this process from these data. Results We describe a computational method for the discovery of the protein domains and CAZy families involved in microbial plant biomass degradation. Our method furthermore accurately predicts the capability to degrade plant biomass for microbial species from their genome sequences. Application to a large, manually curated data set of microbial degraders and non-degraders identified gene families of enzymes known by physiological and biochemical tests to be implicated in cellulose degradation, such as GH5 and GH6. Additionally, genes of enzymes that degrade other plant polysaccharides, such as hemicellulose, pectins and oligosaccharides, were found, as well as gene families which have not previously been related to the process. For draft genomes reconstructed from a cow rumen metagenome our method predicted Bacteroidetes-affiliated species and a relative to a known plant biomass degrader to be plant biomass degraders. This was supported by the presence of genes encoding enzymatically active glycoside hydrolases in these genomes. Conclusions Our results show the potential of the method for generating novel insights into microbial plant biomass degradation from (meta-)genome data, where there is an increasing production of genome assemblages for uncultured microbes. PMID:23414703

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

PubMed

Lalitha Devi, M; Chandrasekhar, K B

2009-12-05

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

Self-degradable Cementitious Sealing Materials

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

Sugama, T.; Butcher, T., Lance Brothers, Bour, D.

2010-10-01

A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated at temperatures of {ge}200 C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the non-reacted or partially reacted sodium silicatemore » activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was {ge}0.7%. In contrast, no self-degradation was observed from CMC-modified Class G well cement. For 200 C-autoclaved AACMs without CMC, followed by heating at temperatures up to 300 C, they had a compressive strength ranging from 5982 to 4945 psi, which is {approx}3.5-fold higher than that of the commercial Class G well cement; the initial- and final-setting times of this AACM slurry at 85 C were {approx}60 and {approx}90 min. Two well-formed crystalline hydration phases, 1.1 nm tobermorite and calcium silicate hydrate (I), were responsible for developing this excellent high compressive strength. Although CMC is an attractive, as a degradation-promoting additive, its addition to both the AACM and the Class G well cement altered some properties of original cementitious materials; among those were an extending their setting times, an increasing their porosity, and lowering their compressive strength. Nevertheless, a 0.7% CMC-modified AACM as self-degradable cementitious material displayed the following properties before its breakdown by water; {approx}120 min initial- and {approx}180 min final-setting times at 85 C, and 1825 to 1375 psi compressive strength with 51.2 to 55.0% porosity up to 300 C.« less

Validation of a method for the quantitation of ghrelin and unacylated ghrelin by HPLC.

PubMed

Staes, Edith; Rozet, Eric; Ucakar, Bernard; Hubert, Philippe; Préat, Véronique

2010-02-05

An HPLC/UV method was first optimized for the separation and quantitation of human acylated and unacylated (or des-acyl) ghrelin from aqueous solutions. This method was validated by an original approach using accuracy profiles based on tolerance intervals for the total error measurement. The concentration range that achieved adequate accuracy extended from 1.85 to 59.30microM and 1.93 to 61.60microM for acylated and unacylated ghrelin, respectively. Then, optimal temperature, pH and buffer for sample storage were determined. Unacylated ghrelin was found to be stable in all conditions tested. At 37 degrees C acylated ghrelin was stable at pH 4 but unstable at pH 7.4, the main degradation product was unacylated ghrelin. Finally, this validated HPLC/UV method was used to evaluate the binding of acylated and unacylated ghrelin to liposomes.

Staircase-scene-based nonuniformity correction in aerial point target detection systems.

PubMed

Huo, Lijun; Zhou, Dabiao; Wang, Dejiang; Liu, Rang; He, Bin

2016-09-01

Focal-plane arrays (FPAs) are often interfered by heavy fixed-pattern noise, which severely degrades the detection rate and increases the false alarms in airborne point target detection systems. Thus, high-precision nonuniformity correction is an essential preprocessing step. In this paper, a new nonuniformity correction method is proposed based on a staircase scene. This correction method can compensate for the nonlinear response of the detector and calibrate the entire optical system with computational efficiency and implementation simplicity. Then, a proof-of-concept point target detection system is established with a long-wave Sofradir FPA. Finally, the local standard deviation of the corrected image and the signal-to-clutter ratio of the Airy disk of a Boeing B738 are measured to evaluate the performance of the proposed nonuniformity correction method. Our experimental results demonstrate that the proposed correction method achieves high-quality corrections.

Synthesis and screening of one-bead-one-compound cyclic peptide libraries.

PubMed

Qian, Ziqing; Upadhyaya, Punit; Pei, Dehua

2015-01-01

Cyclic peptides have been a rich source of biologically active molecules. Herein we present a method for the combinatorial synthesis and screening of large one-bead-one-compound (OBOC) libraries of cyclic peptides against biological targets such as proteins. Up to ten million different cyclic peptides are rapidly synthesized on TentaGel microbeads by the split-and-pool synthesis method and subjected to a multistage screening protocol which includes magnetic sorting, on-bead enzyme-linked and fluorescence-based assays, and in-solution binding analysis of cyclic peptides selectively released from single beads by fluorescence anisotropy. Finally, the most active hit(s) is identified by the partial Edman degradation-mass spectrometry (PED-MS) method. This method allows a single researcher to synthesize and screen up to ten million cyclic peptides and identify the most active ligand(s) in ~1 month, without the time-consuming and expensive hit resynthesis or the use of any special equipment.

Effects of heating method and conditions on the evaporation rate and quality attributes of black mulberry (Morus nigra) juice concentrate.

PubMed

Fazaeli, Mahboubeh; Hojjatpanah, Ghazale; Emam-Djomeh, Zahra

2013-02-01

Black mulberry juice was concentrated by different heating methods, including conventional heating and microwave heating, at different operational pressures (7.3, 38.5 and 100 kPa). The effects of each method on evaporation rate, quality attributes of concentrated juice were investigated. The final juice concentration of 42° Brix was achieved in 140, 120, and 95 min at 100, 38.5, and 7.3 kPa respectively by using a rotary evaporator. Applying microwave energy decreased required times to 115, 95, and 60 min. The changes in color, anthocyanin content during the concentration processes were investigated. Hunter parameters (L, a, and b) were measured to estimate the intensity of color loss. All Hunter color parameters decreased with time. Results showed that the degradation of color and consequently anthocyanins, was more pronounced in rotary evaporation compared to microwave heating method.

An overview of the environmental applicability of vermicompost: from wastewater treatment to the development of sensitive analytical methods.

PubMed

Pereira, Madson de Godoi; Neta, Lourdes Cardoso de Souza; Fontes, Maurício Paulo Ferreira; Souza, Adriana Nascimento; Matos, Thaionara Carvalho; Sachdev, Raquel de Lima; dos Santos, Arnaud Victor; da Guarda Souza, Marluce Oliveira; de Andrade, Marta Valéria Almeida Santana; Paulo, Gabriela Marinho Maciel; Ribeiro, Joselito Nardy; Ribeiro, Araceli Verónica Flores Nardy

2014-01-01

The use of vermicompost (humified material) for treating wastewaters, remediating polluted soils, improving agricultural productivity, protecting crop production, and developing sensitive analytical methods is reviewed here, covering the past 17 years. The main advantages of vermicompost, considering all applications covered in this paper, comprise (i) easy acquisition, (ii) low costs, (iii) structural, chemical, and biological characteristics responsible for exceptional adsorptive capacities as well as pollutant degradation, and (iv) the promotion of biocontrol. Specifically, for wastewater decontamination, a considerable number of works have verified the adsorption of toxic metals, but the application of vermicompost is still scarce for the retention of organic compounds. Problems related to the final disposal of enriched vermicompost (after treatment steps) are often found, in spite of some successful destinations such as organic fertilizer. For decontaminating soils, the use of vermicompost is quite scarce, mainly for inorganic pollutants. In agricultural productivity and biocontrol, vermicompost imparts remarkable benefits regarding soil aggregation, plant nutrition, and the development of beneficial microorganisms against phytopathogens. Finally, the use of vermicompost in sensitive analytical methods for quantifying toxic metals is the newest application of this adsorbent.

An Overview of the Environmental Applicability of Vermicompost: From Wastewater Treatment to the Development of Sensitive Analytical Methods

PubMed Central

Pereira, Madson de Godoi; Cardoso de Souza Neta, Lourdes; Fontes, Maurício Paulo Ferreira; Souza, Adriana Nascimento; Carvalho Matos, Thaionara; de Lima Sachdev, Raquel; dos Santos, Arnaud Victor; Oliveira da Guarda Souza, Marluce; de Andrade, Marta Valéria Almeida Santana; Marinho Maciel Paulo, Gabriela; Ribeiro, Joselito Nardy; Verónica Flores Nardy Ribeiro, Araceli

2014-01-01

The use of vermicompost (humified material) for treating wastewaters, remediating polluted soils, improving agricultural productivity, protecting crop production, and developing sensitive analytical methods is reviewed here, covering the past 17 years. The main advantages of vermicompost, considering all applications covered in this paper, comprise (i) easy acquisition, (ii) low costs, (iii) structural, chemical, and biological characteristics responsible for exceptional adsorptive capacities as well as pollutant degradation, and (iv) the promotion of biocontrol. Specifically, for wastewater decontamination, a considerable number of works have verified the adsorption of toxic metals, but the application of vermicompost is still scarce for the retention of organic compounds. Problems related to the final disposal of enriched vermicompost (after treatment steps) are often found, in spite of some successful destinations such as organic fertilizer. For decontaminating soils, the use of vermicompost is quite scarce, mainly for inorganic pollutants. In agricultural productivity and biocontrol, vermicompost imparts remarkable benefits regarding soil aggregation, plant nutrition, and the development of beneficial microorganisms against phytopathogens. Finally, the use of vermicompost in sensitive analytical methods for quantifying toxic metals is the newest application of this adsorbent. PMID:24578668

Liquid chromatography/tandem mass spectrometry study of forced degradation of azilsartan medoxomil potassium.

PubMed

Swain, Debasish; Patel, Prinesh N; Palaniappan, Ilayaraja; Sahu, Gayatri; Samanthula, Gananadhamu

2015-08-15

Azilsartan medoxomil potassium (AZM) is a new antihypertensive drug introduced in the year 2011. The presence of degradation products not only affects the quality, but also the safety aspects of the drug. Thus, it is essential to develop an efficient analytical method which could be useful to selectively separate and identify the degradation products of azilsartan medoxomil potassium. AZM 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(®) C18 CSH column with mobile phase consisting of 0.02% trifluoroacetic acid and acetonitrile using a gradient method. Identification and characterization of the degradation products was carried out using LC/electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOFMS). A total of five degradation products (DP 1 to DP 5) were formed under various stress conditions and their structures were proposed with the help of tandem mass spectrometry (MS/MS) experiments and accurate mass data. A common degradation product (DP 4) was observed under all the degradation conditions. DP 1, DP 2 and DP 5 were observed under acid hydrolytic conditions whereas DP 3 was observed under alkaline conditions. AZM was found to degrade under hydrolytic, oxidative and photolytic stress conditions. The structures of all the degradation products were proposed. The degradation pathway for the formation of degradation products was also hypothesized. A selective method was developed to quantify the drug in the presence of degradation products which is useful to monitor the quality of AZM. Copyright © 2015 John Wiley & Sons, Ltd.

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.

Task 90-17: Decontaminability study on the U. S. Army Resuscitation Device, Individual, Chemical (RDIC). Final report, 1 Oct 90-24 Jan 91

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

Dill, G.S.; Leonard, R.D.

1991-04-01

A study was performed to determine the effect of three commonly used field decontaminants, DS2, super tropical bleach (STB), and the M270 Decontaminating Kit, Individual (DKIE), on the Resuscitation Device, Chemical, Individual (RDIC). The RDIC system was analyzed to determine which components were accessible to chemical agents and could be degraded by them. The chemical agent susceptibility of the silicone rubber components is the weakest point in the RDIC system. The lack of accessibility of key components to the wetted DKIE wipes and the deterioration of key components by DS2 eliminates these two methods as possible decontaminant methods. STB hadmore » no noticeable effects on the RDIC and is recommended as the best field decontamination method.« less

Comparing Standard and Selective Degradation DNA Extraction Methods: Results from a Field Experiment with Sexual Assault Kits^.

PubMed

Campbell, Rebecca; Pierce, Steven J; Sharma, Dhruv B; Shaw, Jessica; Feeney, Hannah; Nye, Jeffrey; Schelling, Kristin; Fehler-Cabral, Giannina

2017-01-01

A growing number of U.S. cities have large numbers of untested sexual assault kits (SAKs) in police property facilities. Testing older kits and maintaining current case work will be challenging for forensic laboratories, creating a need for more efficient testing methods. We evaluated selective degradation methods for DNA extraction using actual case work from a sample of previously unsubmitted SAKs in Detroit, Michigan. We randomly assigned 350 kits to either standard or selective degradation testing methods and then compared DNA testing rates and CODIS entry rates between the two groups. Continuation-ratio modeling showed no significant differences, indicating that the selective degradation method had no decrement in performance relative to customary methods. Follow-up equivalence tests indicated that CODIS entry rates for the two methods could differ by more than ±5%. Selective degradation methods required less personnel time for testing and scientific review than standard testing. © 2016 American Academy of Forensic Sciences.

A new method for weakening the combined effect of residual errors on multibeam bathymetric data

NASA Astrophysics Data System (ADS)

Zhao, Jianhu; Yan, Jun; Zhang, Hongmei; Zhang, Yuqing; Wang, Aixue

2014-12-01

Multibeam bathymetric system (MBS) has been widely applied in the marine surveying for providing high-resolution seabed topography. However, some factors degrade the precision of bathymetry, including the sound velocity, the vessel attitude, the misalignment angle of the transducer and so on. Although these factors have been corrected strictly in bathymetric data processing, the final bathymetric result is still affected by their residual errors. In deep water, the result usually cannot meet the requirements of high-precision seabed topography. The combined effect of these residual errors is systematic, and it's difficult to separate and weaken the effect using traditional single-error correction methods. Therefore, the paper puts forward a new method for weakening the effect of residual errors based on the frequency-spectrum characteristics of seabed topography and multibeam bathymetric data. Four steps, namely the separation of the low-frequency and the high-frequency part of bathymetric data, the reconstruction of the trend of actual seabed topography, the merging of the actual trend and the extracted microtopography, and the accuracy evaluation, are involved in the method. Experiment results prove that the proposed method could weaken the combined effect of residual errors on multibeam bathymetric data and efficiently improve the accuracy of the final post-processing results. We suggest that the method should be widely applied to MBS data processing in deep water.

Recognizing characters of ancient manuscripts

NASA Astrophysics Data System (ADS)

Diem, Markus; Sablatnig, Robert

2010-02-01

Considering printed Latin text, the main issues of Optical Character Recognition (OCR) systems are solved. However, for degraded handwritten document images, basic preprocessing steps such as binarization, gain poor results with state-of-the-art methods. In this paper ancient Slavonic manuscripts from the 11th century are investigated. In order to minimize the consequences of false character segmentation, a binarization-free approach based on local descriptors is proposed. Additionally local information allows the recognition of partially visible or washed out characters. The proposed algorithm consists of two steps: character classification and character localization. Initially Scale Invariant Feature Transform (SIFT) features are extracted which are subsequently classified using Support Vector Machines (SVM). Afterwards, the interest points are clustered according to their spatial information. Thereby, characters are localized and finally recognized based on a weighted voting scheme of pre-classified local descriptors. Preliminary results show that the proposed system can handle highly degraded manuscript images with background clutter (e.g. stains, tears) and faded out characters.

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

Identification of multi-insecticide residues using GC-NPD and the degradation kinetics of chlorpyrifos in sweet corn and soils.

PubMed

Wang, Peidan; Rashid, Muhammad; Liu, Jie; Hu, Meiying; Zhong, Guohua

2016-12-01

Because more than one insecticide is applied to crops to protect plants from pests, an analytical multi-residue determination method was developed using gas chromatography with a nitrogen phosphorus detector (GC-NPD). The retention time for 12 insecticides was 3.7-27.7min. Under the selected conditions, the limits of detection (LOD) and quantification (LOQ) were below the maximum residue limits (MRLs) and in the range of 0.00315-0.05μgmL(-1) and 0.01-0.165μgmL(-1), respectively. Using GC-NPD, we investigated the dissipation dynamics and final residual levels of chlorpyrifos in sweet corn and soil and determined that the half-lives was 4-7days, that is, that chlorpyrifos is safe to use on sweet corn with a pre-harvest interval of 16-22days before harvest. These results provide new insights into chlorpyrifos degradation in plants and its environmental behavior. Copyright © 2016. Published by Elsevier Ltd.

Performance degradation of space Stirling cryocoolers due to gas contamination

NASA Astrophysics Data System (ADS)

Liu, Xin-guang; Wu, Yi-nong; Yang, Shao-hua; Zhang, Xiao-ming; Lu, Guo-hua; Zhang, Li

2011-08-01

With extensive application of infrared detective techniques, Stirling cryocoolers, used as an active cooling source, have been developed vigorously in China. After the cooler's cooling performance can satisfy the mission's request, its reliability level is crucial for its application. Among all the possible failure mechanisms, gas contamination has been found to be the most notorious cause of cooler's performance degradation by failure analyses. To analyze the characteristic of gas contamination, some experiments were designed and carried out to quantitatively analyze the relationship between failure and performance. Combined with the test results and the outgassing characteristic of non-metal materials in the cryocooler, a degradation model of cooling performance was given by T(t)=T0+A[1-exp(-t/B)] under some assumptions, where t is the running time, T is the Kelvin cooling temperature, and T0, A, B are model parameters, which can be given by the least square method. Here T0 is the fitting initial cooling temperature, A is the maximum range of performance degradation, and B is the time dependent constant of degradation. But the model parameters vary when a cryocooler is running at different cooling temperature ranges, or it is treated by different cleaning process. In order to verify the applicability of the degradation model, data fit analysis on eight groups of cooler's lifetime test was carried out. The final work indicated this model fit well with the performance degradation of space Stirling cryocoolers due to gas contamination and this model could be used to predict or evaluation the cooler's lifetime. Gaseous contamination will not arouse severe performance degradation until the contaminants accumulate to a certain amount, but it could be fatal when it works. So it is more serious to the coolers whose lifetime is more than 10,000 h. The measures taken to control or minimize its damage were discussed as well. To the long-life cryocooler, internal materials must be baked and organic/epoxy materials should be used as few as possible. Further more, pipeline for filling working fluid must have purifying facilities.

A novel mechanochemical method for reconstructing the moisture-degraded HKUST-1.

PubMed

Sun, Xuejiao; Li, Hao; Li, Yujie; Xu, Feng; Xiao, Jing; Xia, Qibin; Li, Yingwei; Li, Zhong

2015-07-11

A novel mechanochemical method was proposed to reconstruct quickly moisture-degraded HKUST-1. The degraded HKUST-1 can be restored within minutes. The reconstructed samples were characterized, and confirmed to have 95% surface area and 92% benzene capacity of the fresh HKUST-1. It is a simple and effective strategy for degraded MOF reconstruction.

Isolation of AHL-degrading bacteria from micro-algal cultures and their impact on algal growth and on virulence of Vibrio campbellii to prawn larvae.

PubMed

Pande, Gde Sasmita Julyantoro; Natrah, Fatin Mohd Ikhsan; Flandez, Ace Vincent Bravo; Kumar, Uday; Niu, Yufeng; Bossier, Peter; Defoirdt, Tom

2015-12-01

Inactivation of quorum sensing (QS) signal molecules, such as acylhomoserine lactones (AHLs) of pathogenic bacteria, has been proposed as a novel method to combat bacterial diseases in aquaculture. Despite the importance of micro-algae for aquaculture, AHL degradation by bacteria associated with micro-algal cultures has thus far not been investigated. In this study, we isolated Pseudomonas sp. NFMI-T and Bacillus sp. NFMI-C from open cultures of the micro-algae Tetraselmis suecica and Chaetoceros muelleri, respectively. An AHL degradation assay showed that either monocultures or co-cultures of the isolates were able to degrade the AHL N-hexanoyl-L-homoserine lactone. In contrast, only Bacillus sp. NFMI-C was able to inactivate N-hydroxybutanoyl-L-homoserine lactone, the AHL produced by Vibrio campbellii. The isolated bacteria were able to persist for up to 3 weeks in conventionalized micro-algal cultures, indicating that they were able to establish and maintain themselves within open algal cultures. Using gnotobiotic algal cultures, we found that the isolates did not affect growth of the micro-algae from which they were isolated, whereas a mixture of both isolates increased the growth of Tetraselmis and decreased the growth of Chaetoceros. Finally, addition of Bacillus sp. NFMI-C to the rearing water of giant river prawn (Macrobrachium rosenbergii) larvae significantly improved survival of the larvae when challenged with pathogenic V. campbellii, whereas it had no effect on larval growth.

Matching rendered and real world images by digital image processing

NASA Astrophysics Data System (ADS)

Mitjà, Carles; Bover, Toni; Bigas, Miquel; Escofet, Jaume

2010-05-01

Recent advances in computer-generated images (CGI) have been used in commercial and industrial photography providing a broad scope in product advertising. Mixing real world images with those rendered from virtual space software shows a more or less visible mismatching between corresponding image quality performance. Rendered images are produced by software which quality performance is only limited by the resolution output. Real world images are taken with cameras with some amount of image degradation factors as lens residual aberrations, diffraction, sensor low pass anti aliasing filters, color pattern demosaicing, etc. The effect of all those image quality degradation factors can be characterized by the system Point Spread Function (PSF). Because the image is the convolution of the object by the system PSF, its characterization shows the amount of image degradation added to any taken picture. This work explores the use of image processing to degrade the rendered images following the parameters indicated by the real system PSF, attempting to match both virtual and real world image qualities. The system MTF is determined by the slanted edge method both in laboratory conditions and in the real picture environment in order to compare the influence of the working conditions on the device performance; an approximation to the system PSF is derived from the two measurements. The rendered images are filtered through a Gaussian filter obtained from the taking system PSF. Results with and without filtering are shown and compared measuring the contrast achieved in different final image regions.

Methods And Systms For Analyzing The Degradation And Failure Of Mechanical Systems

DOEpatents

Jarrell, Donald B.; Sisk, Daniel R.; Hatley, Darrel D.; Kirihara, Leslie J.; Peters, Timothy J.

2005-02-08

Methods and systems for identifying, understanding, and predicting the degradation and failure of mechanical systems are disclosed. The methods include measuring and quantifying stressors that are responsible for the activation of degradation mechanisms in the machine component of interest. The intensity of the stressor may be correlated with the rate of physical degradation according to some determinable function such that a derivative relationship exists between the machine performance, degradation, and the underlying stressor. The derivative relationship may be used to make diagnostic and prognostic calculations concerning the performance and projected life of the machine. These calculations may be performed in real time to allow the machine operator to quickly adjust the operational parameters of the machinery in order to help minimize or eliminate the effects of the degradation mechanism, thereby prolonging the life of the machine. Various systems implementing the methods are also disclosed.

Current remote sensing approaches to monitoring forest degradation in support of countries measurement, reporting and verification (MRV) systems for REDD.

PubMed

Mitchell, Anthea L; Rosenqvist, Ake; Mora, Brice

2017-12-01

Forest degradation is a global phenomenon and while being an important indicator and precursor to further forest loss, carbon emissions due to degradation should also be accounted for in national reporting within the frame of UN REDD+. At regional to country scales, methods have been progressively developed to detect and map forest degradation, with these based on multi-resolution optical, synthetic aperture radar (SAR) and/or LiDAR data. However, there is no one single method that can be applied to monitor forest degradation, largely due to the specific nature of the degradation type or process and the timeframe over which it is observed. The review assesses two main approaches to monitoring forest degradation: first, where detection is indicated by a change in canopy cover or proxies, and second, the quantification of loss (or gain) in above ground biomass (AGB). The discussion only considers degradation that has a visible impact on the forest canopy and is thus detectable by remote sensing. The first approach encompasses methods that characterise the type of degradation and track disturbance, detect gaps in, and fragmentation of, the forest canopy, and proxies that provide evidence of forestry activity. Progress in these topics has seen the extension of methods to higher resolution (both spatial and temporal) data to better capture the disturbance signal, distinguish degraded and intact forest, and monitor regrowth. Improvements in the reliability of mapping methods are anticipated by SAR-optical data fusion and use of very high resolution data. The second approach exploits EO sensors with known sensitivity to forest structure and biomass and discusses monitoring efforts using repeat LiDAR and SAR data. There has been progress in the capacity to discriminate forest age and growth stage using data fusion methods and LiDAR height metrics. Interferometric SAR and LiDAR have found new application in linking forest structure change to degradation in tropical forests. Estimates of AGB change have been demonstrated at national level using SAR and LiDAR-assisted approaches. Future improvements are anticipated with the availability of next generation LiDAR sensors. Improved access to relevant satellite data and best available methods are key to operational forest degradation monitoring. Countries will need to prioritise their monitoring efforts depending on the significance of the degradation, balanced against available resources. A better understanding of the drivers and impacts of degradation will help guide monitoring and restoration efforts. Ultimately we want to restore ecosystem service and function in degraded forests before the change is irreversible.

Microbial flora analysis for the degradation of beta-cypermethrin.

PubMed

Qi, Zhang; Wei, Zhang

2017-03-01

In the Xinjiang region of Eurasia, sustained long-term and continuous cropping of cotton over a wide expanse of land is practiced, which requires application of high levels of pyrethroid and other classes of pesticides-resulting in high levels of pesticide residues in the soil. In this study, soil samples were collected from areas of long-term continuous cotton crops with the aim of obtaining microbial resources applicable for remediation of pyrethroid pesticide contamination suitable for the soil type and climate of that area. Soil samples were first used to culture microbial flora capable of degrading beta-cypermethrin using an enrichment culture method. Structural changes and ultimate microbial floral composition during enrichment were analyzed by high-throughput sequencing. Four strains capable of degrading beta-cypermethrin were isolated and preliminarily classified. Finally, comparative rates and speeds of degradation of beta-cypermethrin between relevant microbial flora and single strains were determined. After continuous subculture for 3 weeks, soil sample microbial flora formed a new type of microbial flora by rapid succession, which showed stable growth by utilizing beta-cypermethrin as the sole carbon source (GXzq). This microbial flora mainly consisted of Pseudomonas, Hyphomicrobium, Dokdonella, and Methyloversatilis. Analysis of the microbial flora also permitted separation of four additional strains; i.e., GXZQ4, GXZQ6, GXZQ7, and GXZQ13 that, respectively, belonged to Streptomyces, Enterobacter, Streptomyces, and Pseudomonas. Under culture conditions of 37 °C and 180 rpm, the degradation rate of beta-cypermethrin by GXzq was as high as 89.84% within 96 h, which exceeded that achieved by the single strains GXZQ4, GXZQ6, GXZQ7, and GXZQ13 and their derived microbial flora GXh.

Use of Both Anode and Cathode Reactions in Wastewater Treatment

NASA Astrophysics Data System (ADS)

Brillas, Enric; Sirés, Ignasi; Cabot, Pere LluíS.

Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical (•OH) produced from anode and/or cathode reactions. H2O2 is generated from the two-electron reduction of O2 at reticulated vitreous carbon, graphite, carbon-felt, and O2-diffusion cathodes. The most usual method is electro-Fenton where Fe2 + added to the wastewater reacts with electrogenerated H2O2 to yield •OH and Fe3 + from Fenton's reaction. An advantage of this technique is that Fe2 + is continuously regenerated from cathodic reduction of Fe3 +. The characteristics of different electro-Fenton systems where pollutants are simultaneously destroyed by •OH formed in the medium from Fenton's reaction and at the anode surface from water oxidation are explained. The effect of the anode [Pt or boron-doped diamond (BDD)] and cathode (carbon-felt or O2-diffusion) on the degradation rate of persistent industrial by-products, herbicides, pharmaceuticals, dyes, etc. is examined. Initial pollutants react much more rapidly with •OH formed in the medium and their degradation sequences are discussed from aromatic intermediates and finally short aliphatic acids are detected. The synergetic positive catalytic effect of Cu2 + on the electro-Fenton process is evidenced. The photoelectro-Fenton method involves the irradiation of the wastewater with UVA light that rapidly photodecomposes complexes of Fe3 + with final carboxylic acids enhancing total decontamination. The peroxicoagulation method uses a sacrificial Fe anode that is continuously oxidized to Fe2 + and organics are either mineralized with •OH formed from both electrogenerated Fe2 + and H2O2 or removed by parallel coagulation with the FeOH3 precipitate formed from the excess of Fe3 + generated from Fenton's reaction.

Improving global CD uniformity by optimizing post-exposure bake and develop sequences

NASA Astrophysics Data System (ADS)

Osborne, Stephen P.; Mueller, Mark; Lem, Homer; Reyland, David; Baik, KiHo

2003-12-01

Improvements in the final uniformity of masks can be shrouded by error contributions from many sources. The final Global CD Uniformity (GCDU) of a mask is degraded by individual contributions of the writing tool, the Post Applied Bake (PAB), the Post Exposure Bake (PEB), the Develop sequence and the Etch step. Final global uniformity will improve by isolating and minimizing the variability of the PEB and Develop. We achieved this de-coupling of the PEB and Develop process from the whole process stream by using "dark loss" which is the loss of unexposed resist during the develop process. We confirmed a correspondence between Angstroms of dark loss and nanometer sized deviations in the chrome CD. A plate with a distinctive dark loss pattern was related to a nearly identical pattern in the chrome CD. This pattern was verified to have originated during the PEB process and displayed a [Δ(Final CD)/Δ(Dark Loss)] ratio of 6 for TOK REAP200 resist. Previous papers have reported a sensitive linkage between Angstroms of dark loss and nanometers in the final uniformity of the written plate. These initial studies reported using this method to improve the PAB of resists for greater uniformity of sensitivity and contrast. Similarly, this paper demonstrates an outstanding optimization of PEB and Develop processes.

Hydrogeological modeling constraints provided by geophysical and geochemical mapping of a chlorinated ethenes plume in northern France

NASA Astrophysics Data System (ADS)

Razafindratsima, Stephen; Guérin, Roger; Bendjoudi, Hocine; de Marsily, Ghislain

2014-09-01

A methodological approach is described which combines geophysical and geochemical data to delineate the extent of a chlorinated ethenes plume in northern France; the methodology was used to calibrate a hydrogeological model of the contaminants' migration and degradation. The existence of strong reducing conditions in some parts of the aquifer is first determined by measuring in situ the redox potential and dissolved oxygen, dissolved ferrous iron and chloride concentrations. Electrical resistivity imaging and electromagnetic mapping, using the Slingram method, are then used to determine the shape of the pollutant plume. A decreasing empirical exponential relation between measured chloride concentrations in the water and aquifer electrical resistivity is observed; the resistivity formation factor calculated at a few points also shows a major contribution of chloride concentration in the resistivity of the saturated porous medium. MODFLOW software and MT3D99 first-order parent-daughter chain reaction and the RT3D aerobic-anaerobic model for tetrachloroethene (PCE)/trichloroethene (TCE) dechlorination are finally used for a first attempt at modeling the degradation of the chlorinated ethenes. After calibration, the distribution of the chlorinated ethenes and their degradation products simulated with the model approximately reflects the mean measured values in the observation wells, confirming the data-derived image of the plume.

Large-area synthesis of high-quality monolayer 1T’-WTe2 flakes

NASA Astrophysics Data System (ADS)

Naylor, Carl H.; Parkin, William M.; Gao, Zhaoli; Kang, Hojin; Noyan, Mehmet; Wexler, Robert B.; Tan, Liang Z.; Kim, Youngkuk; Kehayias, Christopher E.; Streller, Frank; Zhou, Yu Ren; Carpick, Robert; Luo, Zhengtang; Park, Yung Woo; Rappe, Andrew M.; Drndić, Marija; Kikkawa, James M.; Johnson, A. T. Charlie

2017-06-01

Large-area growth of monolayer films of the transition metal dichalcogenides is of the utmost importance in this rapidly advancing research area. The mechanical exfoliation method offers high quality monolayer material but it is a problematic approach when applied to materials that are not air stable. One important example is 1T’-WTe2, which in multilayer form is reported to possess a large non saturating magnetoresistance, pressure induced superconductivity, and a weak antilocalization effect, but electrical data for the monolayer is yet to be reported due to its rapid degradation in air. Here we report a reliable and reproducible large-area growth process for obtaining many monolayer 1T’-WTe2 flakes. We confirmed the composition and structure of monolayer 1T’-WTe2 flakes using x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, atomic force microscopy, Raman spectroscopy and aberration corrected transmission electron microscopy. We studied the time dependent degradation of monolayer 1T’-WTe2 under ambient conditions, and we used first-principles calculations to identify reaction with oxygen as the degradation mechanism. Finally we investigated the electrical properties of monolayer 1T’-WTe2 and found metallic conduction at low temperature along with a weak antilocalization effect that is evidence for strong spin-orbit coupling.

Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite

PubMed Central

Zhang, Xinying; Wu, Yan; Xiao, Gao; Tang, Zhenping; Wang, Meiyin; Liu, Fuchang; Zhu, Xuefeng

2017-01-01

Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C3N4-P25) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria. PMID:28273118

Chemical degradation and morphological instabilities during focused ion beam prototyping of polymers.

PubMed

Orthacker, A; Schmied, R; Chernev, B; Fröch, J E; Winkler, R; Hobisch, J; Trimmel, G; Plank, H

2014-01-28

Focused ion beam processing of low melting materials, such as polymers or biological samples, often leads to chemical and morphological instabilities which prevent the straight-forward application of this versatile direct-write structuring method. In this study the behaviour of different polymer classes under ion beam exposure is investigated using different patterning parameters and strategies with the aim of (i) correlating local temperatures with the polymers' chemistry and its morphological consequences; and (ii) finding a way of processing sensitive polymers with lowest chemical degradation while maintaining structuring times. It is found that during processing of polymers three temperature regimes can be observed: (1) at low temperatures all polymers investigated show stable chemical and morphological behaviour; (2) very high temperatures lead to strong chemical degradation which entails unpredictable morphologies; and (3) in the intermediate temperature regime the behaviour is found to be strongly material dependent. A detailed look reveals that polymers which rather cross-link in the proximity of the beam show stable morphologies in this intermediate regime, while polymers that rather undergo chain scission show tendencies to develop a creeping phase, where material follows the ion beam movement leading to instable and unpredictable morphologies. Finally a simple, alternative patterning strategy is suggested, which allows stable processing conditions with lowest chemical damage even for challenging polymers undergoing chain scission.

Risk Assessment During the Final Phase of an Uncontrolled Re-Entry

NASA Astrophysics Data System (ADS)

Gaudel, A.; Hourtolle, C.; Goester, J. F.; Fuentes, N.

2013-09-01

As French National Space Agency, CNES is empowered to monitor compliance with technical regulations of the French Space Operation Act, FSOA, and to take all necessary measures to ensure the safety of people, property, public health and environment for all space operations involving French responsibility at international level.Therefore, CNES developed ELECTRA that calculates the risk for ground population involved in three types of events: rocket launching, controlled re-entry and uncontrolled re-entry. For the first two cases, ELECTRA takes into account degraded cases due to a premature stop of propulsion.Major evolutions were implemented recently on ELECTRA to meet new users' requirements, like the risk assessment during the final phase of uncontrolled re-entry, that can be combined with the computed risk for each country involved by impacts.The purpose of this paper is to provide an overview of the ELECTRA method and main functionalities, and then to highlight these recent improvements.

Biodegradation of dichlorodiphenyltrichloroethane: intermediates in dichlorodiphenylacetic acid metabolism by aerobacter aerogenes

USGS Publications Warehouse

Wedemeyer, Gary

1967-01-01

The final product of dichlorodiphenyltrichloroethane (DDT) degradation by vertebrates is commonly considered to be dichlorodiphenylacetic acid, DDA. Recently, certain organisms have been found to degrade further DDA to dichlorobenzophenone (DBP), but the possibility that such degradation was due to microbial action could not be excluded. Significantly, dichlorobenzhydrol (DBH), dichlorophenylmethane (DPM), and dichlorodiphenylethylene (DDE) have been tentatively identified in rats fed DDA. Since DDA as well as DDT is degraded by the ubiquitous microorganism Aerobacter aerogenes, it seemed reasonable that the intestinal microflora might be involved in DBP formation, DPM and DBH being intermediates in its pathway from DDA. Since DDA is a (3,y-unsaturated acid, ketone formation via an alkene and an alcohol would be expected.

Practical Approaches to Forced Degradation Studies of Vaccines.

PubMed

Hasija, Manvi; Aboutorabian, Sepideh; Rahman, Nausheen; Ausar, Salvador F

2016-01-01

During the early stages of vaccine development, forced degradation studies are conducted to provide information about the degradation properties of vaccine formulations. In addition to supporting the development of analytical methods for the detection of degradation products, these stress studies are used to identify optimal long-term storage conditions and are part of the regulatory requirements for the submission of stability data. In this chapter, we provide detailed methods for forced degradation analysis under thermal, light, and mechanical stress conditions.

A quantitative PCR approach for quantification of functional genes involved in the degradation of polycyclic aromatic hydrocarbons in contaminated soils.

PubMed

Shahsavari, Esmaeil; Aburto-Medina, Arturo; Taha, Mohamed; Ball, Andrew S

2016-01-01

Polycyclic aromatic hydrocarbons (PAHs) are major pollutants globally and due to their carcinogenic and mutagenic properties their clean-up is paramount. Bioremediation or using PAH degrading microorganisms (mainly bacteria) to degrade the pollutants represents cheap, effective methods. These PAH degraders harbor functional genes which help microorganisms use PAHs as source of food and energy. Most probable number (MPN) and plate counting methods are widely used for counting PAHs degraders; however, as culture based methods only count a small fraction (<1%) of microorganisms capable of carrying out PAH degradation, the use of culture-independent methodologies is desirable.•This protocol presents a robust, rapid and sensitive qPCR method for the quantification of the functional genes involved in the degradation of PAHs in soil samples.•This protocol enables us to screen a vast number of PAH contaminated soil samples in few hours.•This protocol provides valuable information about the natural attenuation potential of contaminated soil and can be used to monitor the bioremediation process.

A method for the evaluation of image quality according to the recognition effectiveness of objects in the optical remote sensing image using machine learning algorithm.

PubMed

Yuan, Tao; Zheng, Xinqi; Hu, Xuan; Zhou, Wei; Wang, Wei

2014-01-01

Objective and effective image quality assessment (IQA) is directly related to the application of optical remote sensing images (ORSI). In this study, a new IQA method of standardizing the target object recognition rate (ORR) is presented to reflect quality. First, several quality degradation treatments with high-resolution ORSIs are implemented to model the ORSIs obtained in different imaging conditions; then, a machine learning algorithm is adopted for recognition experiments on a chosen target object to obtain ORRs; finally, a comparison with commonly used IQA indicators was performed to reveal their applicability and limitations. The results showed that the ORR of the original ORSI was calculated to be up to 81.95%, whereas the ORR ratios of the quality-degraded images to the original images were 65.52%, 64.58%, 71.21%, and 73.11%. The results show that these data can more accurately reflect the advantages and disadvantages of different images in object identification and information extraction when compared with conventional digital image assessment indexes. By recognizing the difference in image quality from the application effect perspective, using a machine learning algorithm to extract regional gray scale features of typical objects in the image for analysis, and quantitatively assessing quality of ORSI according to the difference, this method provides a new approach for objective ORSI assessment.

Quantification of acidic compounds in complex biomass-derived streams

DOE PAGES

Karp, Eric M.; Nimlos, Claire T.; Deutch, Steve; ...

2016-05-10

Biomass-derived streams that contain acidic compounds from the degradation of lignin and polysaccharides (e.g. black liquor, pyrolysis oil, pyrolytic lignin, etc.) are chemically complex solutions prone to instability and degradation during analysis, making quantification of compounds within them challenging. Here we present a robust analytical method to quantify acidic compounds in complex biomass-derived mixtures using ion exchange, sample reconstitution in pyridine and derivatization with BSTFA. The procedure is based on an earlier method originally reported for kraft black liquors and, in this work, is applied to identify and quantify a large slate of acidic compounds in corn stover derived alkalinemore » pretreatment liquor (APL) as a function of pretreatment severity. Analysis of the samples is conducted with GCxGC-TOFMS to achieve good resolution of the components within the complex mixture. The results reveal the dominant low molecular weight components and their concentrations as a function of pretreatment severity. Application of this method is also demonstrated in the context of lignin conversion technologies by applying it to track the microbial conversion of an APL substrate. Here as well excellent results are achieved, and the appearance and disappearance of compounds is observed in agreement with the known metabolic pathways of two bacteria, indicating the sample integrity was maintained throughout analysis. Finally, it is shown that this method applies more generally to lignin-rich materials by demonstrating its usefulness in analysis of pyrolysis oil and pyrolytic lignin.« less

Comparison of oxytetracycline degradation behavior in pig manure with different antibiotic addition methods.

PubMed

Wang, Yan; Chen, Guixiu; Liang, Juanboo; Zou, Yongde; Wen, Xin; Liao, Xindi; Wu, Yinbao

2015-12-01

Using manure collected from swine fed with diet containing antibiotics and antibiotic-free swine manure spiked with antibiotics are the two common methods of studying the degradation behavior of veterinary antibiotic in manure in the environment. However, few studies had been conducted to co-compare these two different antibiotic addition methods. This study used oxytetracycline (OTC) as a model antibiotic to study antibiotic degradation behavior in manure under the above two OTC addition methods. In addition, the role of microorganisms present in the manure on degradation behavior was also examined. The results showed that degradation half-life of OTC in manure from swine fed OTC (9.04 days) was significantly shorter than that of the manure directly treated with OTC (9.65 days). Concentration of 4-epi-OTC in manure from swine fed OTC peaked earlier than that in manure spiked with OTC, and the degradation rates of 4-epi-OTC and α-apo-OTC in the manure from swine fed OTC were faster, but the peak concentrations were lower, than those in manure spiked with OTC. Bacterial diversity and relative abundance of Bacillus cereus data demonstrated that sterilization of the manure before experiment significantly decreased OTC degradation rate in both of the addition methods. Results of the present study demonstrated that the presence of the metabolites (especially 4-epi-OTC) and microorganisms had significant influence on OTC degradation.

High-throughput characterization of sediment organic matter by pyrolysis-gas chromatography/mass spectrometry and multivariate curve resolution: A promising analytical tool in (paleo)limnology.

PubMed

Tolu, Julie; Gerber, Lorenz; Boily, Jean-François; Bindler, Richard

2015-06-23

Molecular-level chemical information about organic matter (OM) in sediments helps to establish the sources of OM and the prevalent degradation/diagenetic processes, both essential for understanding the cycling of carbon (C) and of the elements associated with OM (toxic trace metals and nutrients) in lake ecosystems. Ideally, analytical methods for characterizing OM should allow high sample throughput, consume small amounts of sample and yield relevant chemical information, which are essential for multidisciplinary, high-temporal resolution and/or large spatial scale investigations. We have developed a high-throughput analytical method based on pyrolysis-gas chromatography/mass spectrometry and automated data processing to characterize sedimentary OM in sediments. Our method consumes 200 μg of freeze-dried and ground sediment sample. Pyrolysis was performed at 450°C, which was found to avoid degradation of specific biomarkers (e.g., lignin compounds, fresh carbohydrates/cellulose) compared to 650°C, which is in the range of temperatures commonly applied for environmental samples. The optimization was conducted using the top ten sediment samples of an annually resolved sediment record (containing 16-18% and 1.3-1.9% of total carbon and nitrogen, respectively). Several hundred pyrolytic compound peaks were detected of which over 200 were identified, which represent different classes of organic compounds (i.e., n-alkanes, n-alkenes, 2-ketones, carboxylic acids, carbohydrates, proteins, other N compounds, (methoxy)phenols, (poly)aromatics, chlorophyll and steroids/hopanoids). Technical reproducibility measured as relative standard deviation of the identified peaks in triplicate analyses was 5.5±4.3%, with 90% of the RSD values within 10% and 98% within 15%. Finally, a multivariate calibration model was calculated between the pyrolytic degradation compounds and the sediment depth (i.e., sediment age), which is a function of degradation processes and changes in OM source type. This allowed validation of the Py-GC/MS dataset against fundamental processes involved in OM cycling in aquatic ecosystems. Copyright © 2015 Elsevier B.V. All rights reserved.

Target capture enrichment of nuclear SNP markers for massively parallel sequencing of degraded and mixed samples.

PubMed

Bose, Nikhil; Carlberg, Katie; Sensabaugh, George; Erlich, Henry; Calloway, Cassandra

2018-05-01

DNA from biological forensic samples can be highly fragmented and present in limited quantity. When DNA is highly fragmented, conventional PCR based Short Tandem Repeat (STR) analysis may fail as primer binding sites may not be present on a single template molecule. Single Nucleotide Polymorphisms (SNPs) can serve as an alternative type of genetic marker for analysis of degraded samples because the targeted variation is a single base. However, conventional PCR based SNP analysis methods still require intact primer binding sites for target amplification. Recently, probe capture methods for targeted enrichment have shown success in recovering degraded DNA as well as DNA from ancient bone samples using next-generation sequencing (NGS) technologies. The goal of this study was to design and test a probe capture assay targeting forensically relevant nuclear SNP markers for clonal and massively parallel sequencing (MPS) of degraded and limited DNA samples as well as mixtures. A set of 411 polymorphic markers totaling 451 nuclear SNPs (375 SNPs and 36 microhaplotype markers) was selected for the custom probe capture panel. The SNP markers were selected for a broad range of forensic applications including human individual identification, kinship, and lineage analysis as well as for mixture analysis. Performance of the custom SNP probe capture NGS assay was characterized by analyzing read depth and heterozygote allele balance across 15 samples at 25 ng input DNA. Performance thresholds were established based on read depth ≥500X and heterozygote allele balance within ±10% deviation from 50:50, which was observed for 426 out of 451 SNPs. These 426 SNPs were analyzed in size selected samples (at ≤75 bp, ≤100 bp, ≤150 bp, ≤200 bp, and ≤250 bp) as well as mock degraded samples fragmented to an average of 150 bp. Samples selected for ≤75 bp exhibited 99-100% reportable SNPs across varied DNA amounts and as low as 0.5 ng. Mock degraded samples at 1 ng and 10 ng exhibited >90% reportable SNPs. Finally, two-person male-male mixtures were tested at 10 ng in contributor varying ratios. Overall, 85-100% of alleles unique to the minor contributor were observed at all mixture ratios. Results from these studies using the SNP probe capture NGS system demonstrates proof of concept for application to forensically relevant degraded and mixed DNA samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Mechanical behaviour׳s evolution of a PLA-b-PEG-b-PLA triblock copolymer during hydrolytic degradation.

PubMed

Breche, Q; Chagnon, G; Machado, G; Girard, E; Nottelet, B; Garric, X; Favier, D

2016-07-01

PLA-b-PEG-b-PLA is a biodegradable triblock copolymer that presents both the mechanical properties of PLA and the hydrophilicity of PEG. In this paper, physical and mechanical properties of PLA-b-PEG-b-PLA are studied during in vitro degradation. The degradation process leads to a mass loss, a decrease of number average molecular weight and an increase of dispersity index. Mechanical experiments are made in a specific experimental set-up designed to create an environment close to in vivo conditions. The viscoelastic behaviour of the material is studied during the degradation. Finally, the mechanical behaviour is modelled with a linear viscoelastic model. A degradation variable is defined and included in the model to describe the hydrolytic degradation. This variable is linked to physical parameters of the macromolecular polymer network. The model allows us to describe weak deformations but become less accurate for larger deformations. The abilities and limits of the model are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

A historical review of the methods of determination of soil properties for soil quality and land degradation assessment

NASA Astrophysics Data System (ADS)

Pulido, Manuel; Schnabel, Susanne; Francisco Lavado Contador, Joaquín; Gómez-Gutiérrez, Álvaro; Miralles, Isabel; Lozano-Parra, Javier; Antoneli, Valdemir; Brevik, Eric C.; Cerdà, Artemi

2017-04-01

Properly assessing soil quality and land degradation is one of the main concerns of soil scientists in recent decades. Nowadays there are several available assessment systems based mainly on indicators, i.e. on soil-related parameters, that allow one to determine the current state of natural soils at different scales. These systems vary depending on ecosystem type and soil function studied as well as the accuracy of the methods (techniques and tools) historically used in the determination of several soil parameters. In this study, we show a historical review of many methods of determining soil properties used regularly as soil quality and land degradation indicators. We have considered 5 worldwide historical periods: [1] The pioneers: before 1889, [2] USDA impulse: 1889 - 1945, [3] Productivity paradigm: 1946 - 1972, [4] Conservationist paradigm: 1973 - 2001, and [5] Current methodologies: 2002 - present. The limits of each period have been determined according to some key milestones, for humanity in general and soil science in particular, such as the creation of the United States Department of Agriculture (USDA) in 1889, the end of World War II in 1945 or the publication of relevant works such as The limits to growth in 1972. The development of the Soil Management Assessment Framework (SMAF) indexing tool by American soil scientists in 2001 marks a turning point from which new methodologies and paradigms began to be dominant among methods of determination. Finally, the methods historically used to determine more than 100 soil properties have been reviewed by consulting around 1,500 references published between 1305 and 2017. Approximately 10% of the references were key works to contextualize the first two historical periods, i.e. before 1945, and almost half of all references were published in the second half of the twentieth century (1946 - 2001). A logical tendency in gaining progressively accuracy in methods has been observed as well as a major boom in the study of biochemical properties such as enzyme activity in the last period.

Solar TiO2-assisted photocatalytic degradation of IGCC power station effluents using a Fresnel lens.

PubMed

Monteagudo, J M; Durán, A; Guerra, J; García-Peña, F; Coca, P

2008-03-01

The heterogeneous TiO2 assisted photocatalytic degradation of wastewater from a thermoelectric power station under concentrated solar light irradiation using a Fresnel lens has been studied. The efficiency of photocatalytic degradation was determined from the analysis of cyanide and formate removal. Firstly, the influence of the initial concentration of H2O2 and TiO2 on the degradation kinetics of cyanides and formates was studied based on a factorial experimental design. Experimental kinetic constants were fitted using neural networks. Results showed that the photocatalytic process was effective for cyanides destruction (mainly following a molecular mechanism), whereas most of formates (degraded mainly via a radical path) remained unaffected. Finally, to improve formates degradation, the effect of lowering pH on their degradation rate was evaluated after complete cyanide destruction. The photooxidation efficiency of formates reaches a maximum at pH around 5-6. Above pH 6, formate anion is subjected to electrostatic repulsion with the negative surface of TiO2. At pH<4.5, formate adsorption and photon absorption are reduced due to some catalyst agglomeration.

Photocatalytic degradation kinetics and mechanism of phenobarbital in TiO(2) aqueous solution.

PubMed

Cao, Hua; Lin, Xiulian; Zhan, Haiying; Zhang, Hong; Lin, Jingxin

2013-01-01

5-Ethyl-5-phenylpyrimidine-2,4,6(1H, 3H, 5H)-trione is an anti-convulsant used to treat disorders of movement, e.g. tremors. This work deals with the transformation of phenobarbital by UV/TiO(2) heterogeneous photocatalysis, to assess the decomposition of the pharmaceutical compound, to identify intermediates, as well as to elucidate some mechanistic details of the degradation. The photocatalytic removal efficiency of 100 μm phenobarbital is about 80% within 60 min, while the degradation efficiency of phenobarbital was better in alkaline solution. The study on contribution of reactive oxidative species (ROSs) has shown that ()OH is responsible for the major degradation of phenobarbital, while the photohole, photoelectrons and the other ROSs have the minor contribution to the degradation. Finally, based on the identification of degradation intermediates, two main photocatalytic degradation pathways have been tentatively proposed, including the hydroxylation and cleavage of pyrimidine ring in the phenobarbital molecule respectively. Certainly, the phenobarbital can be mineralized when the photocatalytic reaction time prolongs. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bioaugmentation of half-matured granular sludge with special microbial culture promoted establishment of 2,4-dichlorophenoxyacetic acid degrading aerobic granules.

PubMed

Quan, Xiangchun; Ma, Jingyun; Xiong, Weicong; Wang, Xinrui

2015-06-01

Aerobic granular sludge degrading recalcitrant compounds are generally hard to be cultivated. This study investigated the feasibility of cultivating 2,4-dichlorophenoxyacetic acid (2,4-D) degrading aerobic granules using half-matured sludge granules pre-grown on glucose as the seeds and bioaugmentation with a 2,4-D degrading strain Achromobacter sp. QXH. Results showed that bioaugmentation promoted the steady transformation of glucose-grown granules to 2,4-D degrading sludge granules and fast establishment of 2,4-D degradation ability. The 2,4-D degradation rate of the bioaugmented granules was enhanced by 36-62 % compared to the control at 2,4-D concentrations of 144-565 mg/L on Day 18. The inoculated strain was incorporated into the half-matured granules successfully and survived till the end of operation (220 days). Sludge granules at a mean size of 420 µm and capable of utilizing 500 mg/L 2,4-D as the sole carbon source were finally obtained. Sludge microbial community shifted slightly during the whole operation and the dominant bacteria species belonged to Proteobacteria.

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.

Phenol degradation catalyzed by a peroxidase mimic constructed through the grafting of heme onto metal-organic frameworks.

PubMed

Jiang, Wei; Yang, Jiebing; Wang, Xinghuo; Han, Haobo; Yang, Yan; Tang, Jun; Li, Quanshun

2018-01-01

The aim of this work was to construct a peroxidase mimic for achieving the phenol degradation through Fenton reaction. The enzyme mimic was synthesized through the conjugation of heme with the amino group of 2-amino-1,4-benzene dicarboxylate in UiO-66-NH 2 (ZrMOF), namely Heme-ZrMOF. Compared to free heme, the composite Heme-ZrMOF exhibited an obviously enhanced ability for phenol degradation with up to 97.3% of phenol removal after 2h. Meanwhile, it could achieve the easy separation of catalyst from the system and the elimination of iron residues in the process of phenol degradation. Finally, the catalyst Heme-ZrMOF was observed to possess good recyclability in the phenol degradation with still 76.2% of phenol removal after 4 cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Fabrication of nanoscale heterostructures comprised of graphene-encapsulated gold nanoparticles and semiconducting quantum dots for photocatalysis.

PubMed

Li, Yuan; Chopra, Nitin

2015-05-21

Patterned growth of multilayer graphene shell encapsulated gold nanoparticles (GNPs) and their covalent linking with inorganic quantum dots are demonstrated. GNPs were grown using a xylene chemical vapor deposition process, where the surface oxidized gold nanoparticles catalyze the multilayer graphene shell growth in a single step process. The graphene shell encapsulating gold nanoparticles could be further functionalized with carboxylic groups, which were covalently linked to amine-terminated quantum dots resulting in GNP-quantum dot heterostructures. The compositions, morphologies, crystallinity, and surface functionalization of GNPs and their heterostructures with quantum dots were evaluated using microscopic, spectroscopic, and analytical methods. Furthermore, optical properties of the derived architectures were studied using both experimental methods and simulations. Finally, GNP-quantum dot heterostructures were studied for photocatalytic degradation of phenol.

Meta-learning framework applied in bioinformatics inference system design.

PubMed

Arredondo, Tomás; Ormazábal, Wladimir

2015-01-01

This paper describes a meta-learner inference system development framework which is applied and tested in the implementation of bioinformatic inference systems. These inference systems are used for the systematic classification of the best candidates for inclusion in bacterial metabolic pathway maps. This meta-learner-based approach utilises a workflow where the user provides feedback with final classification decisions which are stored in conjunction with analysed genetic sequences for periodic inference system training. The inference systems were trained and tested with three different data sets related to the bacterial degradation of aromatic compounds. The analysis of the meta-learner-based framework involved contrasting several different optimisation methods with various different parameters. The obtained inference systems were also contrasted with other standard classification methods with accurate prediction capabilities observed.

Wood species affect the degradation of crude oil in beach sand.

PubMed

Jandl, Gerald; Rodríguez Arranz, Alberto; Baum, Christel; Leinweber, Peter

2015-01-01

The addition of wood chips as a co-substrate can promote the degradation of oil in soil. Therefore, in the present study, the tree species-specific impact of wood chips of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and Western balsam poplar (Populus trichocarpa L.) on the degradation of crude oil was tested in beach sand in a 4-week incubation experiment. The CO2-C release increased in the order of control without wood chips < +spruce < +pine < +poplar. Initial and final hydrocarbon concentrations (C10 to C40), as indicators for the oil degradation, were determined with gas chromatography-flame ionization detection (GC-FID). The degradation increased for the light fraction (C10 to C22), the heavy fraction (C23 to C40) as well as the whole range (C10 to C40) in the order of control without wood chips (f(degrad.) = 23% vs. 0% vs. 12%) < +poplar (f(degrad.) = 49% vs. 19% vs. 36%) < +spruce (f(degrad.) = 55% vs. 34% vs. 46%) < +pine (f(degrad.) = 60% vs. 44% vs. 53%), whereas the heavy fraction was less degraded in comparison to the light fraction. It can be concluded, that the tree species-specific wood quality is a significant control of the impact on the degradation of hydrocarbons, and pine wood chips might be promising, possibly caused by their lower decomposability and lower substrate replacement than the other wood species.

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.

Effect of actinobacteria agent inoculation methods on cellulose degradation during composting based on redundancy analysis.

PubMed

Zhao, Yue; Lu, Qian; Wei, Yuquan; Cui, Hongyang; Zhang, Xu; Wang, Xueqin; Shan, Si; Wei, Zimin

2016-11-01

In this study, actinobacteria agent including Streptomyces sp. and Micromonospora sp. were inoculated during chicken manure composting by different inoculation methods. The effect of different treatments on cellulose degradation and the relationship between inoculants and indigenous actinobacteria were investigated during composting. The results showed that inoculation in different stages of composting all improved the actinobacteria community diversity particularly in the cooling stage of composting (M3). Moreover, inoculation could distinctly accelerate the degradation of organic matters (OM) especially celluloses. Redundancy analysis indicated that the correlation between indigenous actinobacteria and degradation of OM and cellulose were regulated by inoculants and there were significant differences between different inoculation methods. Furthermore, synergy between indigenous actinobacteria and inoculants for degradation of OM and cellulose in M3 was better than other treatments. Conclusively, we suggested an inoculation method to regulate the indigenous actinobacteria based on the relationship between inoculants and indigenous actinobacteria and degradation content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interaction of nickel-based SOFC anodes with trace contaminants from coal-derived synthesis gas

NASA Astrophysics Data System (ADS)

Hackett, Gregory Allen

New and efficient methods of producing electrical energy from natural resources have become an important topic for researchers. Integrated gasification and fuel cell (IGFC) systems offer a fuel-flexible, high-efficiency method of energy generation. Specifically, in coal gasification processes, coal can be changed into a high-quality gaseous fuel suitable for feeding solid oxide fuel cells (SOFCs). However, trace species found in coal synthesis gas (syngas) may have a deleterious effect on the performance of nickel-based SOFC anodes. Generally, the cost of removing these species down to parts per million (ppm) levels is high. The purpose of this research is to determine the highest amount of contaminant that results in a low rate (˜1% per 1000 h) of cell performance degradation, allowing the SOFC to produce usable power for 40,000 hours. The cell performance degradation rate was determined for benzene, naphthalene, and mercury-doped syngas based on species concentration. Experimental data are fitted with degradation models to predict cell lifetime behavior. From these results, the minimum coal syngas cleanup required for these trace materials is determined. It is found that for a final cell voltage of 0.6 V, naphthalene and benzene must be cleaned to 360 ppm and less than 150 ppm, respectively. No additional cleaning is required for mercury beyond established environmental standards. Additionally, a detailed attack and recovery mechanism is proposed for the hydrocarbon species and their interaction with the fuel cell. This mechanism is proposed by considering the type of degradation models predicted and how carbon would interact with the Ni-YSZ anode to justify those models. The mechanism postulates that carbon is diffusing into the nickel structure, creating a metal solution. Once the nickel is saturated, the carbon begins to deposit on the nickel surface, reducing the electrode active area. The formation of metal solutions and the deposition of carbon results in reduced cell productivity.

Differential Nuclear and Mitochondrial DNA Preservation in Post-Mortem Teeth with Implications for Forensic and Ancient DNA Studies

PubMed Central

Higgins, Denice; Rohrlach, Adam B.; Kaidonis, John; Townsend, Grant; Austin, Jeremy J.

2015-01-01

Major advances in genetic analysis of skeletal remains have been made over the last decade, primarily due to improvements in post-DNA-extraction techniques. Despite this, a key challenge for DNA analysis of skeletal remains is the limited yield of DNA recovered from these poorly preserved samples. Enhanced DNA recovery by improved sampling and extraction techniques would allow further advancements. However, little is known about the post-mortem kinetics of DNA degradation and whether the rate of degradation varies between nuclear and mitochondrial DNA or across different skeletal tissues. This knowledge, along with information regarding ante-mortem DNA distribution within skeletal elements, would inform sampling protocols facilitating development of improved extraction processes. Here we present a combined genetic and histological examination of DNA content and rates of DNA degradation in the different tooth tissues of 150 human molars over short-medium post-mortem intervals. DNA was extracted from coronal dentine, root dentine, cementum and pulp of 114 teeth via a silica column method and the remaining 36 teeth were examined histologically. Real time quantification assays based on two nuclear DNA fragments (67 bp and 156 bp) and one mitochondrial DNA fragment (77 bp) showed nuclear and mitochondrial DNA degraded exponentially, but at different rates, depending on post-mortem interval and soil temperature. In contrast to previous studies, we identified differential survival of nuclear and mtDNA in different tooth tissues. Futhermore histological examination showed pulp and dentine were rapidly affected by loss of structural integrity, and pulp was completely destroyed in a relatively short time period. Conversely, cementum showed little structural change over the same time period. Finally, we confirm that targeted sampling of cementum from teeth buried for up to 16 months can provide a reliable source of nuclear DNA for STR-based genotyping using standard extraction methods, without the need for specialised equipment or large-volume demineralisation steps. PMID:25992635

Pathway for recovery of photo-degraded polymer solar cells by post degradation thermal anneal

DOE PAGES

Bhattacharya, J.; Joshi, P. H.; Biswas, Rana; ...

2017-02-16

The photo-degradation of polymer solar cells is a critical challenge preventing its commercial deployment. We experimentally fabricate organic solar cells and characterize their degradation under solar simulators in an environmental chamber under nitrogen flow, without exposure to oxygen and moisture. We have developed a thermally stable inverted organic solar cell architecture in which light induced degradation of device characteristics can be reversibly annealed to the pristine values. The stable inverted cells utilized MoO x layers that are thermally treated immediately after their deposition on the organic layer, and before metal cathode deposition. Organic solar cells that are photo-degraded in themore » presence of oxygen, however show irreversible degradation that cannot be thermally recovered. The decrease of organic solar cell characteristics correlates with increases in mid-gap electronic states, measured using capacitance spectroscopy and dark current. It is likely the photo-induced defect states caused by local H motion from the alkyl chains to the aromatic backbone, can be reversibly annealed at elevated temperatures after photo-degradation. Finally, our results provide a pathway for improving the stability of organic photovoltaics.« less

Experimental insights into the importance of aquatic bacterial community composition to the degradation of dissolved organic matter

PubMed Central

Logue, Jürg B; Stedmon, Colin A; Kellerman, Anne M; Nielsen, Nikoline J; Andersson, Anders F; Laudon, Hjalmar; Lindström, Eva S; Kritzberg, Emma S

2016-01-01

Bacteria play a central role in the cycling of carbon, yet our understanding of the relationship between the taxonomic composition and the degradation of dissolved organic matter (DOM) is still poor. In this experimental study, we were able to demonstrate a direct link between community composition and ecosystem functioning in that differently structured aquatic bacterial communities differed in their degradation of terrestrially derived DOM. Although the same amount of carbon was processed, both the temporal pattern of degradation and the compounds degraded differed among communities. We, moreover, uncovered that low-molecular-weight carbon was available to all communities for utilisation, whereas the ability to degrade carbon of greater molecular weight was a trait less widely distributed. Finally, whereas the degradation of either low- or high-molecular-weight carbon was not restricted to a single phylogenetic clade, our results illustrate that bacterial taxa of similar phylogenetic classification differed substantially in their association with the degradation of DOM compounds. Applying techniques that capture the diversity and complexity of both bacterial communities and DOM, our study provides new insight into how the structure of bacterial communities may affect processes of biogeochemical significance. PMID:26296065

Pathway for recovery of photo-degraded polymer solar cells by post degradation thermal anneal

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

Bhattacharya, J.; Joshi, P. H.; Biswas, Rana

The photo-degradation of polymer solar cells is a critical challenge preventing its commercial deployment. We experimentally fabricate organic solar cells and characterize their degradation under solar simulators in an environmental chamber under nitrogen flow, without exposure to oxygen and moisture. We have developed a thermally stable inverted organic solar cell architecture in which light induced degradation of device characteristics can be reversibly annealed to the pristine values. The stable inverted cells utilized MoO x layers that are thermally treated immediately after their deposition on the organic layer, and before metal cathode deposition. Organic solar cells that are photo-degraded in themore » presence of oxygen, however show irreversible degradation that cannot be thermally recovered. The decrease of organic solar cell characteristics correlates with increases in mid-gap electronic states, measured using capacitance spectroscopy and dark current. It is likely the photo-induced defect states caused by local H motion from the alkyl chains to the aromatic backbone, can be reversibly annealed at elevated temperatures after photo-degradation. Finally, our results provide a pathway for improving the stability of organic photovoltaics.« less

Blurred Palmprint Recognition Based on Stable-Feature Extraction Using a Vese–Osher Decomposition Model

PubMed Central

Hong, Danfeng; Su, Jian; Hong, Qinggen; Pan, Zhenkuan; Wang, Guodong

2014-01-01

As palmprints are captured using non-contact devices, image blur is inevitably generated because of the defocused status. This degrades the recognition performance of the system. To solve this problem, we propose a stable-feature extraction method based on a Vese–Osher (VO) decomposition model to recognize blurred palmprints effectively. A Gaussian defocus degradation model is first established to simulate image blur. With different degrees of blurring, stable features are found to exist in the image which can be investigated by analyzing the blur theoretically. Then, a VO decomposition model is used to obtain structure and texture layers of the blurred palmprint images. The structure layer is stable for different degrees of blurring (this is a theoretical conclusion that needs to be further proved via experiment). Next, an algorithm based on weighted robustness histogram of oriented gradients (WRHOG) is designed to extract the stable features from the structure layer of the blurred palmprint image. Finally, a normalized correlation coefficient is introduced to measure the similarity in the palmprint features. We also designed and performed a series of experiments to show the benefits of the proposed method. The experimental results are used to demonstrate the theoretical conclusion that the structure layer is stable for different blurring scales. The WRHOG method also proves to be an advanced and robust method of distinguishing blurred palmprints. The recognition results obtained using the proposed method and data from two palmprint databases (PolyU and Blurred–PolyU) are stable and superior in comparison to previous high-performance methods (the equal error rate is only 0.132%). In addition, the authentication time is less than 1.3 s, which is fast enough to meet real-time demands. Therefore, the proposed method is a feasible way of implementing blurred palmprint recognition. PMID:24992328

Blurred palmprint recognition based on stable-feature extraction using a Vese-Osher decomposition model.

PubMed

Hong, Danfeng; Su, Jian; Hong, Qinggen; Pan, Zhenkuan; Wang, Guodong

2014-01-01

As palmprints are captured using non-contact devices, image blur is inevitably generated because of the defocused status. This degrades the recognition performance of the system. To solve this problem, we propose a stable-feature extraction method based on a Vese-Osher (VO) decomposition model to recognize blurred palmprints effectively. A Gaussian defocus degradation model is first established to simulate image blur. With different degrees of blurring, stable features are found to exist in the image which can be investigated by analyzing the blur theoretically. Then, a VO decomposition model is used to obtain structure and texture layers of the blurred palmprint images. The structure layer is stable for different degrees of blurring (this is a theoretical conclusion that needs to be further proved via experiment). Next, an algorithm based on weighted robustness histogram of oriented gradients (WRHOG) is designed to extract the stable features from the structure layer of the blurred palmprint image. Finally, a normalized correlation coefficient is introduced to measure the similarity in the palmprint features. We also designed and performed a series of experiments to show the benefits of the proposed method. The experimental results are used to demonstrate the theoretical conclusion that the structure layer is stable for different blurring scales. The WRHOG method also proves to be an advanced and robust method of distinguishing blurred palmprints. The recognition results obtained using the proposed method and data from two palmprint databases (PolyU and Blurred-PolyU) are stable and superior in comparison to previous high-performance methods (the equal error rate is only 0.132%). In addition, the authentication time is less than 1.3 s, which is fast enough to meet real-time demands. Therefore, the proposed method is a feasible way of implementing blurred palmprint recognition.

Intensity non-uniformity correction in MRI: existing methods and their validation.

PubMed

Belaroussi, Boubakeur; Milles, Julien; Carme, Sabin; Zhu, Yue Min; Benoit-Cattin, Hugues

2006-04-01

Magnetic resonance imaging is a popular and powerful non-invasive imaging technique. Automated analysis has become mandatory to efficiently cope with the large amount of data generated using this modality. However, several artifacts, such as intensity non-uniformity, can degrade the quality of acquired data. Intensity non-uniformity consists in anatomically irrelevant intensity variation throughout data. It can be induced by the choice of the radio-frequency coil, the acquisition pulse sequence and by the nature and geometry of the sample itself. Numerous methods have been proposed to correct this artifact. In this paper, we propose an overview of existing methods. We first sort them according to their location in the acquisition/processing pipeline. Sorting is then refined based on the assumptions those methods rely on. Next, we present the validation protocols used to evaluate these different correction schemes both from a qualitative and a quantitative point of view. Finally, availability and usability of the presented methods is discussed.

Regulation of proteasomal degradation by modulating proteasomal initiation regions

PubMed Central

Takahashi, Kazunobu; Matouschek, Andreas; Inobe, Tomonao

2016-01-01

Methods for regulating the concentrations of specific cellular proteins are valuable tools for biomedical studies. Artificial regulation of protein degradation by the proteasome is receiving increasing attention. Efficient proteasomal protein degradation requires a degron with two components: a ubiquitin tag that is recognized by the proteasome and a disordered region at which the proteasome engages the substrate and initiates degradation. Here we show that degradation rates can be regulated by modulating the disordered initiation region by the binding of modifier molecules, in vitro and in vivo. These results suggest that artificial modulation of proteasome initiation is a versatile method for conditionally inhibiting the proteasomal degradation of specific proteins. PMID:26278914

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.

A modified method for determining the focal ratio degradation and length properties of optical fibres in astronomy

NASA Astrophysics Data System (ADS)

Yan, Yunxiang; Wang, Gang; Sun, Weimin; Luo, A.-Li; Ma, Zhenyu; Li, Jian; Wang, Shuqing

2017-04-01

Focal ratio degradation (FRD) is a major contributor to throughput and light loss in a fibre spectroscopic telescope system. We combine the guided mode theory in geometric optics and a well-known model, the power distribution model (PDM), to predict and explain the FRD dependence properties. We present a robust method by modifying the energy distribution method with f-intercept to control the input condition. This method provides a way to determine the proper position of the fibre end on the focal plane to improve energy utilization and FRD performance, which lifts the relative throughput up to 95 per cent with variation of output focal ratio less than 2 per cent. This method can also help to optimize the arrangement of the position of focal-plane plate to enhance the coupling efficiency in a telescope. To investigate length properties, we modified the PDM by introducing a new parameter, the focal distance f, into the original model to make it available for a multiposition measurement system. The results show that the modified model is robust and feasible for measuring the key parameter d0 to simulate the transmission characteristics. The output focal ratio in the experiment does not follow the prediction trend but shows an interesting phenomenon: the output focal ratio increases first to the peak, then decreases and remains stable finally with increasing fibre length longer than 15 m. This provides a reference for choosing the appropriate length of fibre to improve the FRD performance for the design of the fibre system in a telescope.

CCD radiation damage in ESA Cosmic Visions missions: assessment and mitigation

NASA Astrophysics Data System (ADS)

Lumb, David H.

2009-08-01

Charge Coupled Device (CCD) imagers have been widely used in space-borne astronomical instruments. A frequent concern has been the radiation damage effects on the CCD charge transfer properties. We review some methods for assessing the Charge Transfer Inefficiency (CTI) in CCDs. Techniques to minimise degradation using background charge injection and p-channel CCD architectures are discussed. A critical review of the claims for p-channel architectures is presented. The performance advantage for p-channel CCD performance is shown to be lower than claimed previously. Finally we present some projections for the performance in the context of some future ESA missions.

Integrity management of offshore structures and its implication on computation of structural action effects and resistance

NASA Astrophysics Data System (ADS)

Moan, T.

2017-12-01

An overview of integrity management of offshore structures, with emphasis on the oil and gas energy sector, is given. Based on relevant accident experiences and means to control the associated risks, accidents are categorized from a technical-physical as well as human and organizational point of view. Structural risk relates to extreme actions as well as structural degradation. Risk mitigation measures, including adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of engineering processes, are briefly outlined. The current status of risk and reliability methodology to aid decisions in the integrity management is briefly reviewed. Finally, the need to balance the uncertainties in data, methods and computational efforts and the cautious use and quality assurance and control in applying high fidelity methods to avoid human errors, is emphasized, and with a plea to develop both high fidelity as well as efficient, simplified methods for design.

Reducing the risk of contamination of sterile parenteral products via ready-to-use closure components.

PubMed

Curry, Wayne; Conway, Samuel; Goodfield, Clara; Miller, Kimberly; Mueller, Ronald L; Polini, Eugene

2010-12-01

The preparation of sterile parenteral products requires careful control of all ingredients, materials, and processes to ensure the final product has the identity and strength, and meets the quality and purity characteristics that it purports to possess. Contamination affecting these critical properties of parenteral products can occur in many ways and from many sources. The use of closures supplied by manufacturers in a ready-to-use state can be an effective method for reducing the risk of contamination and improving the quality of the drug product. This article will address contamination attributable to elastomeric container closure components and the regulatory requirements associated with container closure systems. Possible contaminants, including microorganisms, endotoxins, and chemicals, along with the methods by which these contaminants can enter the product will be reviewed. Such methods include inappropriate material selection, improper closure preparation processes, compromised container closure integrity, degradation of closures, and leaching of compounds from the closures.

Degradation of Remazol Red in batik dye waste water by contact glow discharge electrolysis method using NaOH and NaCl electrolytes

NASA Astrophysics Data System (ADS)

Saksono, Nelson; Putri, Dita Amelia; Suminar, Dian Ratna

2017-03-01

Contact Glow Discharge Electrolysis (CGDE) method is one of Plasma Electrolysis technology which has been approved to degrade organic waste water because it is very productive in producing hydroxyl radical. This study aims to degrade Remazol Red by CGDE method and evaluate important parameters that have influent in degradation process of Remazol Red in Batik dye waste water in batch system. The kind of electrolyte (acid and base) and the addition of metal ion such as Fe2+ have affected Remazol Red degradation percentage. Ultraviolet-Visible (UV-Vis) absorption spectra were used to monitor the degradation process. The result of study showed that percentage degradation was 99.97% which obtained by using NaCl 0.02 M with addition Fe2+ 20 ppm, applied voltage 700 volt, anode depth 0.5 cm, initial concentration of Remazol Red 250 ppm and the temperature of solutions was maintained 50-60 ˚C.

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.

Hydroxycinnamic acid degradation, a broadly conserved trait, protects Ralstonia solanacearum from chemical plant defenses and contributes to root colonization and virulence

PubMed Central

Lowe, Tiffany M.; Ailloud, Florent; Allen, Caitilyn

2014-01-01

Plants produce hydroxycinnamic acid defense compounds (HCAs) to combat pathogens, such as the bacterium Ralstonia solanacearum. We showed that an HCA degradation pathway is genetically and functionally conserved across diverse R. solanacearum strains. Further, a Δfcs (feruloyl-CoA synthetase) mutant that cannot degrade HCAs was less virulent on tomato plants. To understand the role of HCA degradation in bacterial wilt disease, we tested the following hypotheses: HCA degradation helps the pathogen (1) grow, as a carbon source; (2) spread, by reducing physical barriers HCA-derived; and (3) survive plant antimicrobial compounds. Although HCA degradation enabled R. solanacearum growth on HCAs in vitro, HCA degradation was dispensable for growth in xylem sap and root exudate, suggesting that HCAs are not significant carbon sources in planta. Acetyl-bromide quantification of lignin demonstrated that R. solanacearum infections did not affect the gross quantity or distribution of stem lignin. However, the Δfcs mutant was significantly more susceptible to inhibition by two HCAs: caffeate and p-coumarate. Finally, plant colonization assays suggested that HCA degradation facilitates early stages of infection and root colonization. Together, these results indicated that ability to degrade HCAs contributes to bacterial wilt virulence by facilitating root entry and by protecting the pathogen from HCA toxicity. PMID:25423265

In vitro and in vivo degradation of potential anti-adhesion materials: Electrospun membranes of poly(ester-amide) based on l-phenylalanine and p-(dioxanone).

PubMed

Wang, Bing; Dong, Jun; Niu, Lijing; Chen, Wenyan; Chen, Dongliang; Shen, Chengyi; Zhu, Jiang; Zhang, Xiaoming

2017-08-01

Electrospun membranes of poly(p-dioxanone-co-l-phenylalanine) (PDPA) hold potential as an anti-adhesion material. Since adjustable degradation properties are important for anti-adhesion materials, in this study, the in vitro and in vivo degradation processes of PDPA electrospun membranes were investigated in detail. The morphological analysis of these membranes revealed the main degradation conditions of PDPA membranes. The weight remaining and molecular weight variation showed that the overall degradation rate of the membranes could be adjusted by modulating the molecular structure of the PDPAs. Especially, α-chymotrypsin could catalyze the degradation process of PDPAs. Based on these results, the in vitro degradation mechanism was demonstrated, and confirmed by 1 H NMR of the hydrolysis products. Finally, the in vivo degradation and biocompatibility of different PDPAs were investigated. The kinetic study showed that the in vitro and in vivo molecular weight loss of PDPAs have the first-order characteristics. The in vivo degradation rate of the most Phe-containing PDPA-3 is the slowest, and this result relates to the biocompatibilities of PDPAs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1369-1378, 2017. © 2016 Wiley Periodicals, Inc.

Widespread promoter-mediated coordination of transcription and mRNA degradation

PubMed Central

2012-01-01

Background Previous work showed that mRNA degradation is coordinated with transcription in yeast, and in several genes the control of mRNA degradation was linked to promoter elements through two different mechanisms. Here we show at the genomic scale that the coordination of transcription and mRNA degradation is promoter-dependent in yeast and is also observed in humans. Results We first demonstrate that swapping upstream cis-regulatory sequences between two yeast species affects both transcription and mRNA degradation and suggest that while some cis-regulatory elements control either transcription or degradation, multiple other elements enhance both processes. Second, we show that adjacent yeast genes that share a promoter (through divergent orientation) have increased similarity in their patterns of mRNA degradation, providing independent evidence for the promoter-mediated coupling of transcription to mRNA degradation. Finally, analysis of the differences in mRNA degradation rates between mammalian cell types or mammalian species suggests a similar coordination between transcription and mRNA degradation in humans. Conclusions Our results extend previous studies and suggest a pervasive promoter-mediated coordination between transcription and mRNA degradation in yeast. The diverse genes and regulatory elements associated with this coordination suggest that it is generated by a global mechanism of gene regulation and modulated by gene-specific mechanisms. The observation of a similar coupling in mammals raises the possibility that coupling of transcription and mRNA degradation may reflect an evolutionarily conserved phenomenon in gene regulation. PMID:23237624

Point spread function modeling and image restoration for cone-beam CT

NASA Astrophysics Data System (ADS)

Zhang, Hua; Huang, Kui-Dong; Shi, Yi-Kai; Xu, Zhe

2015-03-01

X-ray cone-beam computed tomography (CT) has such notable features as high efficiency and precision, and is widely used in the fields of medical imaging and industrial non-destructive testing, but the inherent imaging degradation reduces the quality of CT images. Aimed at the problems of projection image degradation and restoration in cone-beam CT, a point spread function (PSF) modeling method is proposed first. The general PSF model of cone-beam CT is established, and based on it, the PSF under arbitrary scanning conditions can be calculated directly for projection image restoration without the additional measurement, which greatly improved the application convenience of cone-beam CT. Secondly, a projection image restoration algorithm based on pre-filtering and pre-segmentation is proposed, which can make the edge contours in projection images and slice images clearer after restoration, and control the noise in the equivalent level to the original images. Finally, the experiments verified the feasibility and effectiveness of the proposed methods. Supported by National Science and Technology Major Project of the Ministry of Industry and Information Technology of China (2012ZX04007021), Young Scientists Fund of National Natural Science Foundation of China (51105315), Natural Science Basic Research Program of Shaanxi Province of China (2013JM7003) and Northwestern Polytechnical University Foundation for Fundamental Research (JC20120226, 3102014KYJD022)

Thermal stability increase in metallic nanoparticles-loaded cellulose nanocrystal nanocomposites.

PubMed

Goikuria, U; Larrañaga, A; Vilas, J L; Lizundia, E

2017-09-01

Due to the potential of CNC-based flexible materials for novel industrial applications, the aim of this work is to improve the thermal stability of cellulose nanocrystals (CNC) films through a straightforward and scalable method. Based of nanocomposite approach, five different metallic nanoparticles (ZnO, SiO 2 , TiO 2 , Al 2 O 3 and Fe 2 O 3 ) have been co-assembled in water with CNCs to obtain free-standing nanocomposite films. Thermogravimetric analysis (TGA) reveals an increased thermal stability upon nanoparticle. This increase in the thermal stability reaches a maximum of 75°C for the nanocomposites having 10wt% of Fe 2 O 3 and ZnO. The activation energies of thermodegradation process (E a ) determined according to Kissinger and Ozawa-Flynn-Wall methods further confirm the delayed degradation of CNC nanocomposites upon heating. Finally, the changes induced in the crystalline structure during thermodegradation were followed by wide angle X-ray diffraction (WAXD). It is also observed that thermal degradation proceeds at higher temperatures for nanocomposites having metallic nanoparticles. Overall, experimental findings here showed make nanocomposite approach a simple low-cost environmentally-friendly strategy to overcome the relatively poor thermal stability of CNCs when extracted via sulfuric acid assisted hydrolysis of cellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

One-pot ultrasonic-assisted method for preparation of Ag/AgCl sensitized ZnO nanostructures as visible-light-driven photocatalysts

NASA Astrophysics Data System (ADS)

Naghizadeh-Alamdari, Sara; Habibi-Yangjeh, Aziz; Pirhashemi, Mahsa

2015-02-01

Ultrasonic-assisted method was applied for preparation of Ag/AgCl sensitized ZnO nanostructures by one-pot procedure in water without using any post preparation treatments. The resultant nanocomposites were characterized by XRD, EDX, SEM, DRS, XPS, BET, and PL techniques. In the nanocomposites, ZnO and AgCl have wurtzite hexagonal and cubic crystalline phases, respectively and their surface morphologies remarkably change with increasing mole fraction of silver chloride. The EDX and XPS techniques show that the prepared samples are extremely pure. Ability of the nanocomposites for absorption of visible-light irradiation enhanced with increasing AgCl content. Photocatalytic examination of the nanocomposites was carried out using aqueous solution of methylene blue under visible-light irradiation. The degradation rate constant on the nancomposite rapidly increases with mole fraction of silver chloride up to 0.237. Enhancing activity of the nanocomposite was attributed to its ability for absorbing visible light and separation of electron-hole pairs. Furthermore, influence of ultrasonic irradiation time, calcination temperature, catalyst weight, pH of solution, and scavengers of reactive species on the degradation activity was investigated and the results were discussed. Finally, the photocatalyst has good activity after five successive cycles.

Creating an automated chiller fault detection and diagnostics tool using a data fault library.

PubMed

Bailey, Margaret B; Kreider, Jan F

2003-07-01

Reliable, automated detection and diagnosis of abnormal behavior within vapor compression refrigeration cycle (VCRC) equipment is extremely desirable for equipment owners and operators. The specific type of VCRC equipment studied in this paper is a 70-ton helical rotary, air-cooled chiller. The fault detection and diagnostic (FDD) tool developed as part of this research analyzes chiller operating data and detects faults through recognizing trends or patterns existing within the data. The FDD method incorporates a neural network (NN) classifier to infer the current state given a vector of observables. Therefore the FDD method relies upon the availability of normal and fault empirical data for training purposes and therefore a fault library of empirical data is assembled. This paper presents procedures for conducting sophisticated fault experiments on chillers that simulate air-cooled condenser, refrigerant, and oil related faults. The experimental processes described here are not well documented in literature and therefore will provide the interested reader with a useful guide. In addition, the authors provide evidence, based on both thermodynamics and empirical data analysis, that chiller performance is significantly degraded during fault operation. The chiller's performance degradation is successfully detected and classified by the NN FDD classifier as discussed in the paper's final section.

Preparation of photocatalytic ZnO nanoparticles and application in photochemical degradation of betamethasone sodium phosphate using taguchi approach

NASA Astrophysics Data System (ADS)

Giahi, M.; Farajpour, G.; Taghavi, H.; Shokri, S.

2014-07-01

In this study, ZnO nanoparticles were prepared by a sol-gel method for the first time. Taguchi method was used to identify the several factors that may affect degradation percentage of betamethasone sodium phosphate in wastewater in UV/K2S2O8/nano-ZnO system. Our experimental design consisted of testing five factors, i.e., dosage of K2S2O8, concentration of betamethasone sodium phosphate, amount of ZnO, irradiation time and initial pH. With four levels of each factor tested. It was found that, optimum parameters are irradiation time, 180 min; pH 9.0; betamethasone sodium phosphate, 30 mg/L; amount of ZnO, 13 mg; K2S2O8, 1 mM. The percentage contribution of each factor was determined by the analysis of variance (ANOVA). The results showed that irradiation time; pH; amount of ZnO; drug concentration and dosage of K2S2O8 contributed by 46.73, 28.56, 11.56, 6.70, and 6.44%, respectively. Finally, the kinetics process was studied and the photodegradation rate of betamethasone sodium phosphate was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

Kinetics of thermal decomposition of some biomasses in an inert environment. An investigation of the effect of lead loaded by biosorption.

PubMed

Martín-Lara, María Ángeles; Iáñez-Rodríguez, Irene; Blázquez, Gabriel; Quesada, Lucía; Pérez, Antonio; Calero, Mónica

2017-12-01

The thermal behavior of some types of raw and lead-polluted biomasses typical in south Spain was studied by non-isothermal thermogravimetry. Experiments were carried out in nitrogen atmosphere at three heating rates (5, 10 and 20°C/min). The results of thermogravimetric tests carried out proved that the presence of lead did not change the main degradation pathways of selected biomass (almond shell (AS) and olive pomace (OP)). However, from a point of view of mass loss, lead-polluted samples showed higher decomposition temperatures and decomposition at higher rate. The determination of activation energies was performed by isoconversional methods of Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR). In general, lead-polluted samples showed lower activation energies than raw ones. Then, Coast-Redfern method was applied to determine kinetic function. The kinetic function that seems to determine the mechanism of thermal degradation of main components of all samples was nth order reaction. Finally, a model based on three parallel reactions (for three pseudocomponents) that fit to nth order reactions was evaluated. This model was appropriate to predict the pyrolysis behavior of the raw and lead-polluted samples in all pyrolysis conditions studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Method of phorbol ester degradation in Jatropha curcas L. seed cake using rice bran lipase.

PubMed

Hidayat, Chusnul; Hastuti, Pudji; Wardhani, Avita Kusuma; Nadia, Lana Santika

2014-03-01

A novel enzymatic degradation of phorbol esters (PE) in the jatropha seed cake was developed using lipase. Cihera rice bran lipase had the highest ability to hydrolyze PE, and reduced PE to a safe level after 8 h of incubation. Enzymatic degradation may be a promising method for PE degradation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Treatment of smuggled cigarette tobacco by composting process in facultative reactors.

PubMed

Zittel, Rosimara; Pinto da Silva, Cleber; Domingues, Cinthia Eloise; de Oliveira Stremel, Tatiana Roselena; de Almeida, Thiago Eduardo; Vieira Damiani, Gislaine; Xavier de Campos, Sandro

2018-01-01

This paper presents a study on the degradation of smuggled cigarette tobacco combined with domestic organic waste and sawdust or wood chips, using facultative reactor. Four reactors with different amounts of residue were assembled. For the study of the quality of the compost obtained, physicochemical, phytotoxicity and microbiological analyses were carried out. The mixture with wood chips presented the best temperature conditions and pH variation optimizing the degradation. The final germination index (GI) values of all treatments were above the recommended GI value (50%) and the final C/N ratio between 8 and 13 indicated a mature compost. The concentration of metals under study was below the limit allowed for the commercialization. The composting carried out in all facultative reactors provided ideal conditions for the total sterilization of the final compost. Therefore, the treatment of smuggled cigarettes through facultative reactors was efficient to produce stable and mature compost. Copyright © 2017 Elsevier Ltd. All rights reserved.

Final Report Inspection of Aged/Degraded Containments Program.

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

Naus, Dan J; Ellingwood, B R; Oland, C Barry

2005-09-01

The Inspection of Aged/Degraded Containments Program had primary objectives of (1) understanding the significant factors relating corrosion occurrence, efficacy of inspection, and structural capacity reduction of steel containments and liners of reinforced concrete containments; (2) providing the United States Nuclear Regulatory Commission (USNRC) reviewers a means of establishing current structural capacity margins or estimating future residual structural capacity margins for steel containments, and concrete containments as limited by liner integrity; (3) providing recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by USNRC reviewers in assessing the seriousness of reported incidences of containmentmore » degradation; and (4) providing technical assistance to the USNRC (as requested) related to concrete technology. Primary program accomplishments have included development of a degradation assessment methodology; reviews of techniques and methods for inspection and repair of containment metallic pressure boundaries; evaluation of high-frequency acoustic imaging, magnetostrictive sensor, electromagnetic acoustic transducer, and multimode guided plate wave technologies for inspection of inaccessible regions of containment metallic pressure boundaries; development of a continuum damage mechanics-based approach for structural deterioration; establishment of a methodology for reliability-based condition assessments of steel containments and liners; and fragility assessments of steel containments with localized corrosion. In addition, data and information assembled under this program has been transferred to the technical community through review meetings and briefings, national and international conference participation, technical committee involvement, and publications of reports and journal articles. Appendix A provides a listing of program reports, papers, and publications; and Appendix B contains a listing of program-related presentations.« less

Exploring the biochemical properties and remediation applications of the unusual explosive-degrading P450 system XplA/B

PubMed Central

Jackson, Rosamond G.; Rylott, Elizabeth L.; Fournier, Diane; Hawari, Jalal; Bruce, Neil C.

2007-01-01

Widespread contamination of land and groundwater has resulted from the use, manufacture, and storage of the military explosive hexa-hydro-1,3,5-trinitro-1,3,5-triazine (RDX). This contamination has led to a requirement for a sustainable, low-cost method to remediate this problem. Here, we present the characterization of an unusual microbial P450 system able to degrade RDX, consisting of flavodoxin reductase XplB and fused flavodoxin-cytochrome P450 XplA. The affinity of XplA for the xenobiotic compound RDX is high (Kd = 58 μM) and comparable with the Km of other P450s toward their natural substrates (ranging from 1 to 500 μM). The maximum turnover (kcat) is 4.44 per s, only 10-fold less than the fastest self-sufficient P450 reported, BM3. Interestingly, the presence of oxygen determines the final products of RDX degradation, demonstrating that the degradation chemistry is flexible, but both pathways result in ring cleavage and release of nitrite. Carbon monoxide inhibition is weak and yet the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) is a potent inhibitor. To test the efficacy of this system for the remediation of groundwater, transgenic Arabidopsis plants expressing both xplA and xplB were generated. They are able to remove saturating levels of RDX from liquid culture and soil leachate at rates significantly faster than those of untransformed plants and xplA-only transgenic lines, demonstrating the applicability of this system for the phytoremediation of RDX-contaminated sites. PMID:17940033

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.

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.

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.

Edge enhancement algorithm for low-dose X-ray fluoroscopic imaging.

PubMed

Lee, Min Seok; Park, Chul Hee; Kang, Moon Gi

2017-12-01

Low-dose X-ray fluoroscopy has continually evolved to reduce radiation risk to patients during clinical diagnosis and surgery. However, the reduction in dose exposure causes quality degradation of the acquired images. In general, an X-ray device has a time-average pre-processor to remove the generated quantum noise. However, this pre-processor causes blurring and artifacts within the moving edge regions, and noise remains in the image. During high-pass filtering (HPF) to enhance edge detail, this noise in the image is amplified. In this study, a 2D edge enhancement algorithm comprising region adaptive HPF with the transient improvement (TI) method, as well as artifacts and noise reduction (ANR), was developed for degraded X-ray fluoroscopic images. The proposed method was applied in a static scene pre-processed by a low-dose X-ray fluoroscopy device. First, the sharpness of the X-ray image was improved using region adaptive HPF with the TI method, which facilitates sharpening of edge details without overshoot problems. Then, an ANR filter that uses an edge directional kernel was developed to remove the artifacts and noise that can occur during sharpening, while preserving edge details. The quantitative and qualitative results obtained by applying the developed method to low-dose X-ray fluoroscopic images and visually and numerically comparing the final images with images improved using conventional edge enhancement techniques indicate that the proposed method outperforms existing edge enhancement methods in terms of objective criteria and subjective visual perception of the actual X-ray fluoroscopic image. The developed edge enhancement algorithm performed well when applied to actual low-dose X-ray fluoroscopic images, not only by improving the sharpness, but also by removing artifacts and noise, including overshoot. Copyright © 2017 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.

[BiOBr promoted the photocatalytic degradation of beta-cypermethrin under visible light].

PubMed

Peng, Yi-Zhu; Zhao, Xiao-Rong; Jia, Man-Ke; Zhou, Wei; Huang, Ying-Ping

2014-05-01

As a visible light photocatalyst, bismuth oxide bromide (BiOBr) was used to catalyze the degradation of beta-cypermethrin (beta-CP). The photocatalytic degradation of beta-CP was studied with gas chromatography. The effects of pH and catalyst dose on the photocatalytic degradation efficiency were discussed. The oxidization and mineralization of beta-CP were detected by chemical oxygen demand (COD) analyzer. The results showed that beta-CP could be effectively degraded under visible light irradiation using BiOBr as the catalyst. At given experimental conditions, the degradation rate of beta-CP reached 94. 68% after 10 h and the COD removal rate reached 67. 99% after 36 h. With the increase of catalyst dose and pH value, the degradation rate was improved. The photocatalytic oxidation species was determined by peroxidase method and terephthalic acid fluorescence method. These results suggested that the photocatalytic degradation process mainly referred to hydroxyl radical ( OH) mechanism.

Engineered enzymatically active bacteriophages and methods of uses thereof

DOEpatents

Collins, James J [Newton, MA; Kobayashi, Hideki [Yokohama, JP; Kearn, Mads [Ottawa, CA; Araki, Michihiro [Minatoku, JP; Friedland, Ari [Boston, MA; Lu, Timothy Kuan-Ta [Palo Alto, CA

2012-05-22

The present invention provides engineered bacteriophages that express at least one biofilm degrading enzyme on their surface and uses thereof for degrading bacterial biofilms. The invention also provides genetically engineered bacteriophages expressing the biofilm degrading enzymes and proteins necessary for the phage to replicate in different naturally occurring biofilm producing bacteria. The phages of the invention allow a method of biofilm degradation by the use of one or only a few administration of the phage because the system using these phages is self perpetuating, and capable of degrading biofilm even when the concentration of bacteria within the biofilm is low.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; a method supplement for the determination of Fipronil and degradates in water by gas chromatography/mass spectrometry

USGS Publications Warehouse

Madsen, James F.; Sandstrom, Mark W.; Zaugg, Steven D.

2002-01-01

A method for the isolation and detemrination of fipronil and four of its degradates has been developed. This method adapts an analytical method created by the U.S. Geological Survey National Water Quality Laboratory in 1995 for the determination of a broad range of high-use pesticides typically found in filtered natural-water samples. In 2000, fipronil and four of its degradates were extracted, analyzed, and validated using this method. The recoveries for these five compounds in reagent-water samples fortified at 1 microgram per liter (ug/L) avereraged 98 percent. Initial method detection limits averaged 0.0029 ug/L. The performance of these five new compounds is consistent with the performance of the compounds in the initial method, making it possible to include them in addition to the other 41 pesticides and pesticide degradates in the original method.

Antioxidant potential of mulberry and non-mulberry silk sericin and its implications in biomedicine.

PubMed

Kumar, Jadi Praveen; Mandal, Biman B

2017-07-01

Sericin, a principal constituent of silk, is widely used in various biomedical applications. In addition, conferring protection against free radicals and oxidative damage add more value to its therapeutic potential. However, the antioxidant (AO) properties of silk sericin (SS) remains contingent on extraction procedures. In the present study, we have evaluated the effect of different extraction methods (conventional, autoclaving, urea, alkali and acid-degradation) on AO properties of SS from three Indian silk varieties [Antheraea assamensis (AA), Philosamia ricini (PR) and Bombyx mori (BM)]. The physico-chemical characterization studies revealed that the molecular weight of SS isolates of each method ranged from 10 to 220kDa along with varied protein structural biochemistry. SS extracts using urea-degradation (BM, PR and AA), conventional method and alkali-degradation (BM) displayed high percentage of β-sheets, random coils and turns. Acid-degraded SS (PR, followed by AA and BM) showed the highest total flavonoid content while conventional method (PR), autoclaving (AA) and alkali-degradation (BM) displayed lowest flavonoid levels. Interestingly, SS extracted by autoclaving (BM and AA), acid-degradation (PR), conventional and alkali-degradation (BM, AA and PR) methods exhibited 50% reduction of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical. Moreover, the efficacy of antioxidant potential of SS extracted by different methods was found to be in the order of "alkali>autoclaving>conventional" as demonstrated in L929 cells. Correspondingly, the anti-lipid peroxidation activity of SS extracted by alkali method (AA, BM and PR) further confirmed better AO properties amid others. Thus, the present study demonstrates that the extraction methods may significantly affect AO activity of SS which might be of importance for potential cosmetic applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Degradation Kinetics Study of Alogliptin Benzoate in Alkaline Medium by Validated Stability-Indicating HPTLC Method.

PubMed

Bodiwala, Kunjan Bharatkumar; Shah, Shailesh; Thakor, Jeenal; Marolia, Bhavin; Prajapati, Pintu

2016-11-01

A rapid, sensitive, and stability-indicating high-performance thin-layer chromatographic method was developed and validated to study degradation kinetics of Alogliptin benzoate (ALG) in an alkaline medium. ALG was degraded under acidic, alkaline, oxidative, and thermal stress conditions. The degraded samples were chromatographed on silica gel 60F254-TLC plates, developed using a quaternary-solvent system (chloroform-methanol-ethyl acetate-triethyl amine, 9+1+1+0.5, v/v/v/v), and scanned at 278 nm. The developed method was validated per International Conference on Harmonization guidelines using validation parameters such as specificity, linearity and range, precision, accuracy, LOD, and LOQ. The linearity range for ALG was 100-500 ng/band (correlation coefficient = 0.9997) with an average recovery of 99.47%. The LOD and LOQ for ALG were 9.8 and 32.7 ng/band, respectively. The developed method was successfully applied for the quantitative estimation of ALG in its synthetic mixture with common excipients. Degradation kinetics of ALG in an alkaline medium was studied by degrading it under three different temperatures and three different concentrations of alkali. Degradation of ALG in the alkaline medium was found to follow first-order kinetics. Contour plots have been generated to predict degradation rate constant, half-life, and shelf life of ALG in various combinations of temperature and concentration of alkali using Design Expert software.

In vitro degradation kinetics of pure PLA and Mg/PLA composite: Effects of immersion temperature and compression stress.

PubMed

Li, Xuan; Chu, Chenglin; Wei, Yalin; Qi, Chenxi; Bai, Jing; Guo, Chao; Xue, Feng; Lin, Pinghua; Chu, Paul K

2017-01-15

The effects of the immersion temperature and compression stress on the in vitro degradation behavior of pure poly-lactic acid (pure-PLA) and PLA-based composite unidirectionally reinforced with micro-arc oxidized magnesium alloy wires (Mg/PLA or MAO-MAWs/PLA) are investigated. The degradation kinetics of pure-PLA and the PLA matrix in MAO-MAWs/PLA exhibit an Arrhenius-type behavior. For the composite, the synergic degradation of MAO-MAWs maintains a steady pH and mitigates the degradation of PLA matrix during immersion. However, the external compression stress decreases the activation energy (E a ) and pre-exponential factor (k 0 ) consequently increasing the degradation rate of PLA. Under a compression stress of 1MPa, E a and k 0 of pure PLA are 57.54kJ/mol and 9.74×10 7 day -1 , respectively, but 65.5kJ/mol and 9.81×10 8 day -1 for the PLA matrix in the composite. Accelerated tests are conducted in rising immersion temperature in order to shorten the experimental time. Our analysis indicates there are well-defined relationships between the bending strength of the specimens and the PLA molecular weight during immersion, which are independent of the degradation temperature and external compression stress. Finally, a numerical model is established to elucidate the relationship of bending strength, the PLA molecular weight, activation energy, immersion time and temperature. We systematically evaluate the effects of compression stress and temperature on the degradation properties of two materials: (pure-PLA) and MAO-MAWs/PLA (or Mg/PLA). The initial in vitro degradation kinetics of the unstressed or stressed pure-PLA and MAO-MAWs/PLA composite is confirmed to be Arrhenius-like. MAO-MAWs and external compression stress would influence the degradation activation energy (E a ) and pre-exponential factor (k 0 ) of PLA, and we noticed there is a linear relationship between E a and ln k 0 . Thereafter, we noticed that Mg 2+ , not H + , plays a significant role on the mitigation of the PLA degradation and external compression stress brings the molecular structure change of PLA. Finally, we proposed a model to predict the bending strength of the specimens versus immersion time at different immersion temperatures. This fundamental study could provide some scientific basis in our understanding for the evaluations and biomedical applications of these biodegradable materials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Assessing land degradation and acknowledging adaptive policy options to face with changes: an integrated approach applied to a semiarid agropastoral system

NASA Astrophysics Data System (ADS)

Tarrasón, D.; Ravera, F.; Reed, M.; Dougill, A.

2009-04-01

The complexity of assessing land degradation on semiarid systems deals with challenges that have rarely been addressed. Land degradation is a human-induced and permanent reduction of key ecosystem functions and services at different temporal and spatial scale. Initial attempts to assess land degradation at a broader scale were based on expert opinion, however the empirical bases to sustain these estimations are weak and the ecological data are still scarce. In addition, such approaches are essentially subjective and they reflect the objectives and assumptions of those making the assessment, who are rarely land users themselves. Currently, the concept of "land degradation" is debated, and in the last years have emerged a growing number of efforts to develop land degradation participatory assessment methods that could capture a more complex understanding of human-environment interactions. This study proposes an interdisciplinary and hybrid methodology, combining local and scientific knowledge, to assess land degradation in mixed farming systems. Specifically, i) it describes and analyses the mixed farming system and it explores how historically political, social and institutional local factors have interacted with ecological process, ii) it identifies key ecosystem processes and services needed to support the agropastoral systems that are perceived to be under threat from land degradation; iii) it assesses the status and trends of these key ecosystem services; and iv) it identifies and evaluates potential management alternatives to prevent land degradation and cope with changes (e.g. climate change). We show how to achieve, through a co-construction of hybrid knowledge between scientific and farmers, a more accurate and reliable appraisal of land degradation, since farmer's perception is contextualized, dynamic and complex and involves simultaneously multiple temporal and spatial scales and multiple dimensions of analysis that could help the scientific exploration. The study reveals that the ecosystem services' exploration with local actors is a good method to reveal the multiple and sometimes conflictive local strategies and interests at stake. Ecosystem services assessment has also been used as an entry to discuss with local land users about adaptive management strategies to improve soil functions involved in the maintenance of the provision and regulation processes and land productivity that support local livelihoods face to changes. The integrated methodological framework adopted has a positive impact to empower local users, enlarging the access to adequate information and channels of communication between experts/local users, and improving their capacity to use the co-constructed hybrid knowledge. We argue that engaging the relevant and interested actors in the process is key to understand margin of flexibility for dialogue between local users, scientific and policy makers and it is a base for ownership of local actors in decision making processes that facilitates effective soil-land governance. Finally, we discuss how wide institutional changes at different levels are needed to support agro-environmental policies for communities, small and medium farmers and to undertake new adaptive management strategies to cope with uncertainties of future changes.

An efficient and environment-friendly method of removing graphene oxide in wastewater and its degradation mechanisms.

PubMed

Zhang, Chao-Zhi; Li, Ting; Yuan, Yang; Xu, Jianqiang

2016-06-01

Graphene and graphene oxide (GO) have already existed in air, water and soil due to their popular application in functional materials. However, degradation of graphene and GO in wastewater has not been reported. Degradation of GO plays a key role in the elimination of graphene and GO in wastewater due to graphene being easily oxidized to GO. In this paper, GO was completely degraded to give CO2 by Photo-Fenton. The degradation intermediates were determined by UV-vis absorption spectra, elemental analysis (EA), fourier transform infrared (FT-IR) and liquid chromatography-mass spectrometry (LC-MS). Experimental results showed that graphene oxide was completely degraded to give CO2 after 28 days. Based on UV, FT-IR, LC-MS spectra and EA data of these degradation intermediates, the degradation mechanisms of GO were supposed. This paper suggests an efficient and environment-friendly method to degrade GO and graphene. Copyright © 2016 Elsevier Ltd. All rights reserved.

Incipient Fault Detection for Rolling Element Bearings under Varying Speed Conditions.

PubMed

Xue, Lang; Li, Naipeng; Lei, Yaguo; Li, Ningbo

2017-06-20

Varying speed conditions bring a huge challenge to incipient fault detection of rolling element bearings because both the change of speed and faults could lead to the amplitude fluctuation of vibration signals. Effective detection methods need to be developed to eliminate the influence of speed variation. This paper proposes an incipient fault detection method for bearings under varying speed conditions. Firstly, relative residual (RR) features are extracted, which are insensitive to the varying speed conditions and are able to reflect the degradation trend of bearings. Then, a health indicator named selected negative log-likelihood probability (SNLLP) is constructed to fuse a feature set including RR features and non-dimensional features. Finally, based on the constructed SNLLP health indicator, a novel alarm trigger mechanism is designed to detect the incipient fault. The proposed method is demonstrated using vibration signals from bearing tests and industrial wind turbines. The results verify the effectiveness of the proposed method for incipient fault detection of rolling element bearings under varying speed conditions.

Incipient Fault Detection for Rolling Element Bearings under Varying Speed Conditions

PubMed Central

Xue, Lang; Li, Naipeng; Lei, Yaguo; Li, Ningbo

2017-01-01

Varying speed conditions bring a huge challenge to incipient fault detection of rolling element bearings because both the change of speed and faults could lead to the amplitude fluctuation of vibration signals. Effective detection methods need to be developed to eliminate the influence of speed variation. This paper proposes an incipient fault detection method for bearings under varying speed conditions. Firstly, relative residual (RR) features are extracted, which are insensitive to the varying speed conditions and are able to reflect the degradation trend of bearings. Then, a health indicator named selected negative log-likelihood probability (SNLLP) is constructed to fuse a feature set including RR features and non-dimensional features. Finally, based on the constructed SNLLP health indicator, a novel alarm trigger mechanism is designed to detect the incipient fault. The proposed method is demonstrated using vibration signals from bearing tests and industrial wind turbines. The results verify the effectiveness of the proposed method for incipient fault detection of rolling element bearings under varying speed conditions. PMID:28773035

Degradation of learned skills: Effectiveness of practice methods on visual approach and landing skill retention

NASA Technical Reports Server (NTRS)

Sitterley, T. E.; Zaitzeff, L. P.; Berge, W. A.

1972-01-01

Flight control and procedural task skill degradation, and the effectiveness of retraining methods were evaluated for a simulated space vehicle approach and landing under instrument and visual flight conditions. Fifteen experienced pilots were trained and then tested after 4 months either without the benefits of practice or with static rehearsal, dynamic rehearsal or with dynamic warmup practice. Performance on both the flight control and procedure tasks degraded significantly after 4 months. The rehearsal methods effectively countered procedure task skill degradation, while dynamic rehearsal or a combination of static rehearsal and dynamic warmup practice was required for the flight control tasks. The quality of the retraining methods appeared to be primarily dependent on the efficiency of visual cue reinforcement.

Assessment of chloroethene degradation rates based on ratios of daughter/parent compounds in groundwater plumes

NASA Astrophysics Data System (ADS)

Höhener, Patrick

2014-05-01

Chlorinated solvent spills at industrial and urban sites create groundwater plumes where tetrachloro- and trichloroethene may degrade to their daughter compounds, dichloroethenes, vinyl chloride and ethane. The assessment of degradation and natural attenuation at such sites may be based on the analysis and inverse modelling of concentration data, on the calculation of mass fluxes in transsects, and/or on the analysis of stable isotope ratios in the ethenes. Relatively few work has investigated the possibility of using ratio of concentrations for gaining information on degradation rates. The use of ratios bears the advantage that dilution of a single sample with contaminant-free water does not matter. It will be shown that molar ratios of daughter to parent compounds measured along a plume streamline are a rapid and robust mean of determining whether degradation rates increase or decrease along the degradation chain, and allow furthermore a quantitation of the relative magnitude of degradation rates compared to the rate of the parent compound. Furthermore, ratios of concentration will become constant in zones where degradation is absent, and this allows to sketching the extension of actively degrading zones. The assessment is possible for pure sources and also for mixed sources. A quantification method is proposed in order to estimate first-order degradation rates in zones of constant degradation activity. This quantification method includes corrections that are needed due to longitudinal and transversal dispersivity. The method was tested on a number of real field sites from literature. At the majority of these sites, the first-order degradation rates were decreasing along the degradation chain from tetrachloroethene to vinyl chloride, meaning that the latter was often reaching important concentrations. This is bad news for site owners due to the increased toxicity of vinyl chloride compared to its parent compounds.

Bioaugmentation of activated sludge towards 3-chloroaniline removal with a mixed bacterial population carrying a degradative plasmid.

PubMed

Bathe, Stephan; Schwarzenbeck, Norbert; Hausner, Martina

2009-06-01

A bioaugmentation approach combining several strategies was applied to achieve degradation of 3-chloroaniline (3CA) in semicontinuous activated sludge reactors. In a first step, a 3CA-degrading Comamonas testosteroni strain carrying the degradative plasmid pNB2 was added to a biofilm reactor, and complete 3CA degradation together with spread of the plasmid within the indigenous biofilm population was achieved. A second set of reactors was then bioaugmented with either a suspension of biofilm cells removed from the carrier material or with biofilm-containing carrier material. 3CA degradation was established rapidly in all bioaugmented reactors, followed by a slow adaptation of the non-bioaugmented control reactors. In response to variations in 3CA concentration, all reactors exhibited temporary performance breakdowns. Whereas duplicates of the control reactors deviated in their behaviour, the bioaugmented reactors appeared more reproducible in their performance and population dynamics. Finally, the carrier-bioaugmented reactors showed an improved performance in the presence of high 3CA influent concentrations over the suspension-bioaugmented reactors. In contrast, degradation in one control reactor failed completely, but was rapidly established in the remaining control reactor.

Controlling the degradation kinetics of porous iron by poly(lactic-co-glycolic acid) infiltration for use as temporary medical implants

PubMed Central

Yusop, Abdul Hakim Md; Daud, Nurizzati Mohd; Nur, Hadi; Kadir, Mohammed Rafiq Abdul; Hermawan, Hendra

2015-01-01

Iron and its alloy have been proposed as biodegradable metals for temporary medical implants. However, the formation of iron oxide and iron phosphate on their surface slows down their degradation kinetics in both in vitro and in vivo scenarios. This work presents new approach to tailor degradation behavior of iron by incorporating biodegradable polymers into the metal. Porous pure iron (PPI) was vacuum infiltrated by poly(lactic-co-glycolic acid) (PLGA) to form fully dense PLGA-infiltrated porous iron (PIPI) and dip coated into the PLGA to form partially dense PLGA-coated porous iron (PCPI). Results showed that compressive strength and toughness of the PIPI and PCPI were higher compared to PPI. A strong interfacial interaction was developed between the PLGA layer and the iron surface. Degradation rate of PIPI and PCPI was higher than that of PPI due to the effect of PLGA hydrolysis. The fast degradation of PIPI did not affect the viability of human fibroblast cells. Finally, this work discusses a degradation mechanism for PIPI and the effect of PLGA incorporation in accelerating the degradation of iron. PMID:26057073

Biocatalytic degradation of pharmaceuticals, personal care products, industrial chemicals, steroid hormones and pesticides in a membrane distillation-enzymatic bioreactor.

PubMed

Asif, Muhammad B; Hai, Faisal I; Kang, Jinguo; van de Merwe, Jason P; Leusch, Frederic D L; Price, William E; Nghiem, Long D

2018-01-01

Laccase-catalyzed degradation of a broad spectrum of trace organic contaminants (TrOCs) by a membrane distillation (MD)-enzymatic membrane bioreactor (EMBR) was investigated. The MD component effectively retained TrOCs (94-99%) in the EMBR, facilitating their continuous biocatalytic degradation. Notably, the extent of TrOC degradation was strongly influenced by their molecular properties. A significant degradation (above 90%) of TrOCs containing strong electron donating functional groups (e.g., hydroxyl and amine groups) was achieved, while a moderate removal was observed for TrOCs containing electron withdrawing functional groups (e.g., amide and halogen groups). Separate addition of two redox-mediators, namely syringaldehyde and violuric acid, further improved TrOC degradation by laccase. However, a mixture of both showed a reduced performance for a few pharmaceuticals such as primidone, carbamazepine and ibuprofen. Mediator addition increased the toxicity of the media in the enzymatic bioreactor, but the membrane permeate (i.e., final effluent) was non-toxic, suggesting an added advantage of coupling MD with EMBR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Central composite design optimization of pilot plant fluidized-bed heterogeneous Fenton process for degradation of an azo dye.

PubMed

Aghdasinia, Hassan; Bagheri, Rasoul; Vahid, Behrouz; Khataee, Alireza

2016-11-01

Optimization of Acid Yellow 36 (AY36) degradation by heterogeneous Fenton process in a recirculated fluidized-bed reactor was studied using central composite design (CCD). Natural pyrite was applied as the catalyst characterized by X-ray diffraction and scanning electron microscopy. The CCD model was developed for the estimation of degradation efficiency as a function of independent operational parameters including hydrogen peroxide concentration (0.5-2.5 mmol/L), initial AY36 concentration (5-25 mg/L), pH (3-9) and catalyst dosage (0.4-1.2 mg/L). The obtained data from the model are in good agreement with the experimental data (R(2 )= 0.964). Moreover, this model is applicable not only to determine the optimized experimental conditions for maximum AY36 degradation, but also to find individual and interactive effects of the mentioned parameters. Finally, gas chromatography-mass spectroscopy (GC-MS) was utilized for the identification of some degradation intermediates and a plausible degradation pathway was proposed.

New insights into the enhanced performance of high solid anaerobic digestion with dewatered sludge by thermal hydrolysis: Organic matter degradation and methanogenic pathways.

PubMed

Chen, Sisi; Li, Ning; Dong, Bin; Zhao, Wentao; Dai, Lingling; Dai, Xiaohu

2018-01-15

Two lab-scale high solid anaerobic digesters fed with untreated sludge (R1) and thermally hydrolyzed sludge (R2) were operated to investigate the influence of thermal hydrolysis pretreatment (THP) on the degradation of individual macromolecular organic components (MOCs), as well as the functional and metabolic responses of microbes during anaerobic digestion (AD). The degradation of MOCs was improved by THP at different rates, in which improved degradation of proteins (by 49.0%) and hemicelluloses (by 25.0%) were the main factors contributing to the increase in volatile solids (VS) reduction. However, no enhancement of final degradation extent of MOCs was observed. With a more densified microbial population, R2 was also enriched in genes involved in amino acid and carbohydrate metabolism, reflected in the enhanced degradation of proteins and carbohydrates. After THP, the methanogenic pathway shifted from strict acetoclastic methanogenesis to acetoclastic/hydrogenotrophic methanogenesis, consistent with the enhanced methane production and the increase of methane content. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification and characterization of stress degradants of lacosamide by LC-MS and ESI-Q-TOF-MS/MS: development and validation of a stability indicating RP-HPLC method.

PubMed

Ramisetti, Nageswara Rao; Kuntamukkala, Ramakrishna; Lakshetti, Sridhar; Sripadi, Prabhakar

2014-07-01

The current study dealt with the degradation behavior of lacosamide (LAC) under ICH prescribed stress conditions. LAC was found to be labile under acid and base hydrolytic stress conditions, while it was stable to neutral hydrolytic, oxidative, photolytic and thermal stress. In total, seven degradation products (DPs) were formed, which were separated on a C18 column using a stability-indicating method. LC-MS analyses indicated that one of the DPs had the same molecular mass as that of the drug. Structural characterization of DPs was carried out using ESI-Q-TOF-MS/MS technique. The degradation pathways and mechanisms of degradation of the drug were delineated by carrying out the degradation in different co-solvents viz. methanol, deuterated methanol, ethanol, 1-propanol and acetonitrile. The developed LC method was validated for the determination of related substances and assay of LAC as per ICH guidelines. This study demonstrates a comprehensive approach of LAC degradation studies during its development phase. Copyright © 2014. Published by Elsevier B.V.

Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

NASA Astrophysics Data System (ADS)

Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

2016-06-01

Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

Fate of deoxynivalenol and deoxynivalenol-3-glucoside during cereal-based thermal food processing: a review study.

PubMed

Wu, Qinghua; Kuča, Kamil; Humpf, Hans-Ulrich; Klímová, Blanka; Cramer, Benedikt

2017-02-01

Deoxynivalenol (DON), the most commonly occurring trichothecene in nature, may affect animal and human health through causing diarrhea, vomiting, gastrointestinal inflammation, and immunomodulation. DON-3-glucoside (DON-3G) as a major plant metabolite of the mycotoxin is another "emerging" food safety issue in recent years. Humans may experience potential health risks by consuming DON-contaminated food products. Thus, it is crucial for human and animal health to study also the degradation of DON and DON-3G during thermal food processing. Baking, boiling, steaming, frying, and extrusion cooking are commonly used during thermal food processing and have promising effects on the reduction of mycotoxins in food. For DON, however, the observed effects of these methods, as reported in numerous studies, are ambiguous and do not present a clear picture with regard to reduction or transformation. This review summarized the influence of thermal processing on the stability of DON and the formation of degradation/conversion products. Besides this, also a release of DON and DON-3G from food matrix as well as the release of DON from DON-3G during processing is discussed. In addition, some conflicting findings as reported from the studies on thermal processing as well as cause-effect relationships of the different thermal procedures are explored. Finally, the potential toxic profiles of DON degradation products are discussed as well when data are available.

Diclofenac and 2‐anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver

PubMed Central

Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

2012-01-01

Summary The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio‐MnOx), biogenic silver nanoparticles (Bio‐Ag0) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2‐anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio‐MnOx, Bio‐Ag0 and Ag+ separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio‐MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese‐free P. putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co‐metabolic removal during active Mn2+ oxidation by P. putida; (ii) a synergistic interaction between preoxidized Bio‐MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P. putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

Effect of advanced oxidation processes on the micropollutants and the effluent organic matter contained in municipal wastewater previously treated by three different secondary methods.

PubMed

Giannakis, Stefanos; Gamarra Vives, Franco Alejandro; Grandjean, Dominique; Magnet, Anoys; De Alencastro, Luiz Felippe; Pulgarin, César

2015-11-01

In this study, wastewater from the output of three different secondary treatment facilities (Activated Sludge, Moving Bed Bioreactor and Coagulation-Flocculation) present in the municipal wastewater treatment plant of Vidy, Lausanne (Switzerland), was further treated with various oxidation processes (UV, UV/H2O2, solar irradiation, Fenton, solar photo-Fenton), at laboratory scale. For this assessment, 6 organic micropollutants in agreement with the new environmental legislation requirements in Switzerland were selected (Carbamazepine, Clarithromycin, Diclofenac, Metoprolol, Benzotriazole, Mecoprop) and monitored throughout the treatment. Also, the overall removal of the organic load was assessed. After each secondary treatment, the efficiency of the AOPs increased in the following order: Coagulation-Flocculation < Activated Sludge < Moving Bed Bioreactor, in almost all cases. From the different combinations tested, municipal wastewater subjected to biological treatment followed by UV/H2O2 resulted in the highest elimination levels. Wastewater previously treated by physicochemical treatment demonstrated considerably inhibited micropollutant degradation rates. The degradation kinetics were determined, yielding: k (UV) < k (UV/H2O2) and k (Fenton) < k (solar irradiation) < k (photo-Fenton). Finally, the evolution of global pollution parameters (COD & TOC elimination) was followed and the degradation pathways for the effluent organic matter are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling the thermal conductivity of (U xTh 1-x)O 2 and (U xPu 1-x)O 2

DOE PAGES

Cooper, M. W. D.; Middleburgh, S. C.; Grimes, R. W.

2015-07-15

The degradation of thermal conductivity due to the non-uniform cation lattice of (U xTh 1-x)O 2 and (U xPu 1-x)O 2 solid solutions has been investigated by molecular dynamics, using the non-equilibrium method, from 300 to 2000 K. Degradation of thermal conductivity is predicted in (U xTh 1-x)O 2 and (U xPu 1-x)O 2 as compositions deviate from the pure end members: UO 2, PuO 2 and ThO 2. The reduction in thermal conductivity is most apparent at low temperatures where phonon-defect scattering dominates over phonon-phonon interactions. The effect is greater for (U xTh 1-x)O 2 than U xPu 1-x)Omore » 2 due to the greater mismatch in cation size. Parameters for an analytical expressions have been developed that describe the predicted thermal conductivities over the full temperature and compositional ranges. Finally, these expressions may be used in higher level fuel performance codes.« less

Efficient photocatalytic degradation of malachite green dye under visible irradiation by water soluble ZnS:Mn/ZnS core/shell nanoparticles

NASA Astrophysics Data System (ADS)

Khaparde, Rohini A.; Acharya, Smita A.

2018-05-01

ZnS:Mn/ ZnS core/shell nanoparticles was prepared by two step synthesis method. In first step, oleic acid - coated Mn doped ZnS core nanoparticles were prepared which were charged through ligand exchange. Shell of ZnS NPs was finally deposited upon the surface of charged Mn doped ZnS core. Scanning electron microscopy (SEM) image exhibit morphological confirmation of ZnS:Mn/ZnS core/shell. As Nano ZnS are the most suitable candidates for photocatalyst that extensively involved in degradation and complete mineralization of various toxic organic pollutants owing to its high efficiency, strong oxidizing power, non-toxicity, high photochemical and biological stability, corrosive resistance and low cost. Photodegradation of malachite green is systematically investigated by adding different molar proportional of ZnS:Mn/ZnS core/shell in the dye. The rate of de-coloration of dye is detected by UV-VIS absorption spectroscopy. Efficient detoriation in the colour of dye is attributed to the core /shell morphology of the particles.

The regulation by phenolic compounds of soil organic matter dynamics under a changing environment.

PubMed

Min, Kyungjin; Freeman, Chris; Kang, Hojeong; Choi, Sung-Uk

2015-01-01

Phenolics are the most abundant plant metabolites and are believed to decompose slowly in soils compared to other soil organic matter (SOM). Thus, they have often been considered as a slow carbon (C) pool in soil dynamics models. Here, however, we review changes in our concept about the turnover rate of phenolics and quantification of different types of phenolics in soils. Also, we synthesize current research on the degradation of phenolics and their regulatory effects on decomposition. Environmental changes, such as elevated CO2, warming, nitrogen (N) deposition, and drought, could influence the production and form of phenolics, leading to a change in SOM dynamics, and thus we also review the fate of phenolics under environmental disturbances. Finally, we propose the use of phenolics as a tool to control rates of SOM decomposition to stabilize organic carbon in ecosystems. Further studies to clarify the role of phenolics in SOM dynamics should include improving quantification methods, elucidating the relationship between phenolics and soil microorganisms, and determining the interactive effects of combinations of environmental changes on the phenolics production and degradation and subsequent impact on SOM processing.

Introduction of Environmentally Degradable Parameters to Evaluate the Biodegradability of Biodegradable Polymers

PubMed Central

Yang, Chao; Song, Cunjiang; Geng, Weitao; Li, Qiang; Wang, Yuanyuan; Kong, Meimei; Wang, Shufang

2012-01-01

Environmentally Degradable Parameter (Ed K) is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs). In this study, a concept Ed K was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated Ed K was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the Ed K values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of Ed K for each material. The Ed K values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the Ed K was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment. PMID:22675455

Comparative study of DNA encapsulation into PLGA microparticles using modified double emulsion methods and spray drying techniques.

PubMed

Oster, C G; Kissel, T

2005-05-01

Recently, several research groups have shown the potential of microencapsulated DNA as adjuvant for DNA immunization and in tissue engineering approaches. Among techniques generally used for microencapsulation of hydrophilic drug substances into hydrophobic polymers, modified WOW double emulsion method and spray drying of water-in-oil dispersions take a prominent position. The key parameters for optimized microspheres are particle size, encapsulation efficiency, continuous DNA release and stabilization of DNA against enzymatic and mechanical degradation. This study investigates the possibility to encapsulate DNA avoiding shear forces which readily degrade DNA during this microencapsulation. DNA microparticles were prepared with polyethylenimine (PEI) as a complexation agent for DNA. Polycations are capable of stabilizing DNA against enzymatic, as well as mechanical degradation. Further, complexation was hypothesized to facilitate the encapsulation by reducing the size of the macromolecule. This study additionally evaluated the possibility of encapsulating lyophilized DNA and lyophilized DNA/PEI complexes. For this purpose, the spray drying and double emulsion techniques were compared. The size of the microparticles was characterized by laser diffractometry and the particles were visualized by scanning electron microscopy (SEM). DNA encapsulation efficiencies were investigated photometrically after complete hydrolysis of the particles. Finally, the DNA release characteristics from the particles were studied. Particles with a size of <10 microm which represent the threshold for phagocytic uptake could be prepared with these techniques. The encapsulation efficiency ranged from 100-35% for low theoretical DNA loadings. DNA complexation with PEI 25?kDa prior to the encapsulation process reduced the initial burst release of DNA for all techniques used. Spray-dried particles without PEI exhibited high burst releases, whereas double emulsion techniques showed continuous release rates.

Simultaneous determination of some water-soluble vitamins and preservatives in multivitamin syrup by validated stability-indicating high-performance liquid chromatography method.

PubMed

Vidović, Stojanka; Stojanović, Biljana; Veljković, Jelena; Prazić-Arsić, Ljiljana; Roglić, Goran; Manojlović, Dragan

2008-08-22

HPLC stability-indicating method has been developed for the simultaneous determination of some water-soluble vitamins (ascorbic acid, thiamine hydrochloride, riboflavin-5'-phosphate sodium, pyridoxine hydrochloride, nicotinamide, D(+)-panthenol) and two preservatives (methylparaben and sodium benzoate) in multivitamin syrup preparation. Water-soluble vitamins, preservatives and their degradants were separated on Zorbax SB-Aq (C(18)) (250 mm x 4.6 mm, 5 microm) column at an ambient temperature. Combined isocratic and gradient elution was performed with a mobile phase consisting of 0.0125 M hexane-1-sulfonic acid sodium salt in 0.1% (m/v) o-phosphoric acid, pH 2.4-2.5 (solvent A) and acetonitrile (solvent B) at the flow-rate 1 ml min(-1). Starting with solvent A an isocratic elution was performed for 15 min, then the composition was changed to 85% of A and 15% of B during the next 20 min and it was constant for 5 min, then the composition was changed to 70% of A and 30% of B during next 15 min and it was constant for 5 min and finally was changed to 100% of A as at the beginning of the elution. Detection was performed with diode array detector at 210, 230 and 254 nm. Multivitamin syrup preparation was subjected to stress testing (forced degradation) in order to demonstrate that degradants from the vitamins, preservatives and/or product excipients do not interfere with the quantification of vitamins and preservatives. Typical validation characteristics: selectivity, accuracy, precision, linearity, range, limit of quantification and limit of detection were evaluated for vitamins and preservatives.

Risk assessment of false-positive quantitative real-time PCR results in food, due to detection of DNA originating from dead cells.

PubMed

Wolffs, Petra; Norling, Börje; Rådström, Peter

2005-03-01

Real-time PCR technology is increasingly used for detection and quantification of pathogens in food samples. A main disadvantage of nucleic acid detection is the inability to distinguish between signals originating from viable cells and DNA released from dead cells. In order to gain knowledge concerning risks of false-positive results due to detection of DNA originating from dead cells, quantitative PCR (qPCR) was used to investigate the degradation kinetics of free DNA in four types of meat samples. Results showed that the fastest degradation rate was observed (1 log unit per 0.5 h) in chicken homogenate, whereas the slowest rate was observed in pork rinse (1 log unit per 120.5 h). Overall results indicated that degradation occurred faster in chicken samples than in pork samples and faster at higher temperatures. Based on these results, it was concluded that, especially in pork samples, there is a risk of false-positive PCR results. This was confirmed in a quantitative study on cell death and signal persistence over a period of 28 days, employing three different methods, i.e. viable counts, direct qPCR, and finally floatation, a recently developed discontinuous density centrifugation method, followed by qPCR. Results showed that direct qPCR resulted in an overestimation of up to 10 times of the amount of cells in the samples compared to viable counts, due to detection of DNA from dead cells. However, after using floatation prior to qPCR, results resembled the viable count data. This indicates that by using of floatation as a sample treatment step prior to qPCR, the risk of false-positive PCR results due to detection of dead cells, can be minimized.

Kinetic study and mechanism of Niclosamide degradation.

PubMed

Zaazaa, Hala E; Abdelrahman, Maha M; Ali, Nouruddin W; Magdy, Maimana A; Abdelkawy, M

2014-11-11

A spectrophotometric kinetic study of Niclosamide alkaline degradation as a function of drug concentration, alkaline concentration and temperature has been established utilizing double divisor-ratio spectra spectrophotometric method. The developed method allowed determination of Niclosamide in presence of its alkaline degradation products; namely; 2-chloro-4-nitro aniline (DEG I) and 5-chloro salicylic acid (DEG II) with characterization of its degradation mechanism. It was found that degradation kinetic of Niclosamide followed pseudo-first order under the established experimental conditions with a degradation rate constant (k) of 0.0829 mol/h and half life (t1/2) of 8.35 h. The overall degradation rate constant as a function of the temperature under the given conditions obeyed Arrhenius equation where the activation energy was calculated to be 3.41 kcal/mol. Copyright © 2014 Elsevier B.V. All rights reserved.

Advanced Residual Strength Degradation Rate Modeling for Advanced Composite Structures. Volume II. Tasks II and III.

DTIC Science & Technology

1981-07-01

ADVANCED COMPOSITE STRUCTURES VOLUME II - TASKS Ix AND III K. N. Lauraitis Tl J. T. Ryder ?l4 D. E. Pettit ~ Lockheed-California Company S Burbank...Strength Degradation Rate Final Report Modeling for Advanced Composite Structures 1 July 1979 to 29 May 1981 Vol II - Task II and III S. PERFORMIN ONG...identify by block namber) composites , graphite/epoxy, impact damage, damaged holes, fatigue, damage propagation, residual strength, NDI 20. ABSTRACT

Biodegradation of endocrine disruptors in urban wastewater using Pleurotus ostreatus bioreactor.

PubMed

Křesinová, Zdena; Linhartová, Lucie; Filipová, Alena; Ezechiáš, Martin; Mašín, Pavel; Cajthaml, Tomáš

2018-07-25

The white rot fungus Pleurotus ostreatus HK 35, which is also an edible industrial mushroom commonly cultivated in farms, was tested in the degradation of typical representatives of endocrine disrupters (EDCs; bisphenol A, estrone, 17β-estradiol, estriol, 17α-ethinylestradiol, triclosan and 4-n-nonylphenol); its degradation efficiency under model laboratory conditions was greater than 90% within 12 days and better than that of another published strain P. ostreatus 3004. A spent mushroom substrate from a local farm was tested for its applicability in various batch and trickle-bed reactors in degrading EDCs in model fortified and real communal wastewater. The reactors were tested under various regimes including a pilot-scale trickle-bed reactor, which was finally tested at a wastewater treatment plant. The result revealed that the spent substrate is an efficient biodegradation agent, where the fungus was usually able to remove about 95% of EDCs together with suppression of the estrogenic activity of the sample. The results showed the fungus was able to operate in the presence of bacterial microflora in wastewater without any substantial negative effects on the degradation abilities. Finally, a pilot-scale trickle-bed reactor was installed in a wastewater treatment plant and successfully operated for 10days, where the bioreactor was able to remove more than 76% of EDCs present in the wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploration of biodegradation mechanisms of black carbon-bound nonylphenol in black carbon-amended sediment.

PubMed

Cheng, Guanghuan; Sun, Mingyang; Ge, Xinlei; Xu, Xinhua; Lin, Qi; Lou, Liping

2017-12-01

The present study aimed to investigate biodegradation mechanisms of black carbon (BC)-bound contaminants in BC-amended sediment when BC was applied to control organic pollution. The single-point Tenax desorption technique was applied to track the species changes of nonylphenol (NP) during biodegradation process in the rice straw carbon (RC)-amended sediment. And the correlation between the biodegradation and desorption of NP was analyzed. Results showed that microorganisms firstly degraded the rapid-desorbing NP (6 h Tenax desorption) in RC-amended sediment. The biodegradation facilitated the desorption of slow-desorbing NP, which was subsequently degraded as well (192 h Tenax desorption). Notably, the final amount of NP degradation was greater than that of NP desorption, indicating that absorbed NP by RC amendment can be degraded by microorganisms. Finally, the residual NP amount in RC-amended sediment was decided by RC content and its physicochemical property. Moreover, the presence of the biofilm was observed by the confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) so that microorganisms were able to overcome the mass transfer resistance and directly utilized the absorbed NP. Therefore, single-point Tenax desorption alone may not be an adequate basis for the prediction of the bioaccessibility of contaminants to microorganisms or bioremediation potential in BC-amended sediment. Copyright © 2017. Published by Elsevier Ltd.

Light Field Imaging Based Accurate Image Specular Highlight Removal

PubMed Central

Wang, Haoqian; Xu, Chenxue; Wang, Xingzheng; Zhang, Yongbing; Peng, Bo

2016-01-01

Specular reflection removal is indispensable to many computer vision tasks. However, most existing methods fail or degrade in complex real scenarios for their individual drawbacks. Benefiting from the light field imaging technology, this paper proposes a novel and accurate approach to remove specularity and improve image quality. We first capture images with specularity by the light field camera (Lytro ILLUM). After accurately estimating the image depth, a simple and concise threshold strategy is adopted to cluster the specular pixels into “unsaturated” and “saturated” category. Finally, a color variance analysis of multiple views and a local color refinement are individually conducted on the two categories to recover diffuse color information. Experimental evaluation by comparison with existed methods based on our light field dataset together with Stanford light field archive verifies the effectiveness of our proposed algorithm. PMID:27253083

A new stationary gridline artifact suppression method based on the 2D discrete wavelet transform

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

Tang, Hui, E-mail: corinna@seu.edu.cn; Key Laboratory of Computer Network and Information Integration; Centre de Recherche en Information Biomédicale sino-français, Laboratoire International Associé, Inserm, Université de Rennes 1, Rennes 35000

2015-04-15

Purpose: In digital x-ray radiography, an antiscatter grid is inserted between the patient and the image receptor to reduce scattered radiation. If the antiscatter grid is used in a stationary way, gridline artifacts will appear in the final image. In most of the gridline removal image processing methods, the useful information with spatial frequencies close to that of the gridline is usually lost or degraded. In this study, a new stationary gridline suppression method is designed to preserve more of the useful information. Methods: The method is as follows. The input image is first recursively decomposed into several smaller subimagesmore » using a multiscale 2D discrete wavelet transform. The decomposition process stops when the gridline signal is found to be greater than a threshold in one or several of these subimages using a gridline detection module. An automatic Gaussian band-stop filter is then applied to the detected subimages to remove the gridline signal. Finally, the restored image is achieved using the corresponding 2D inverse discrete wavelet transform. Results: The processed images show that the proposed method can remove the gridline signal efficiently while maintaining the image details. The spectra of a 1D Fourier transform of the processed images demonstrate that, compared with some existing gridline removal methods, the proposed method has better information preservation after the removal of the gridline artifacts. Additionally, the performance speed is relatively high. Conclusions: The experimental results demonstrate the efficiency of the proposed method. Compared with some existing gridline removal methods, the proposed method can preserve more information within an acceptable execution time.« less

Follow-up of the fate of imazalil from post-harvest lemon surface treatment to a baking experiment.

PubMed

Vass, Andrea; Korpics, Evelin; Dernovics, Mihály

2015-01-01

Imazalil is one of the most widespread fungicides used for the post-harvest treatment of citrus species. The separate use of peel during food preparation and processing may hitherto concentrate most of the imazalil into food products, where specific maximum residue limits hardly exist for this fungicide. In order to monitor comprehensively the path of imazalil, our study covered the monitoring of the efficiency of several washing treatments, the comparison of operative and related sample preparation methods for the lemon samples, the validation of a sample preparation technique for a fatty cake matrix, the preparation of a model cake sample made separately either with imazalil containing lemon peel or with imazalil spiking, the monitoring of imazalil degradation into α-(2,4-dichlorophenyl)-1H-imidazole-1-ethanol because of the baking process, and finally the mass balance of imazalil throughout the washing experiments and the baking process. Quantification of imazalil was carried out with an LC-ESI-MS/MS set-up, while LC-QTOF was used for the monitoring of imazalil degradation. Concerning the washing, none of the addressed five washing protocols could remove more than 30% of imazalil from the surface of the lemon samples. The study revealed a significant difference between the extraction efficiency of imazalil by the EN 15662:2008 and AOAC 2007.1 methods, with the advantage of the former. The use of the model cake sample helped to validate a modified version of the EN 15662:2008 method that included a freeze-out step to efficiently recover imazalil (>90%) from the fatty cake matrix. The degradation of imazalil during the baking process was significantly higher when this analyte was spiked into the cake matrix than in the case of preparing the cake with imazalil-containing lemon peel (52% vs. 22%). This observation calls the attention to the careful evaluation of pesticide stability data that are based on solution spiking experiments.

Bisulfite Conversion of DNA: Performance Comparison of Different Kits and Methylation Quantitation of Epigenetic Biomarkers that Have the Potential to Be Used in Non-Invasive Prenatal Testing

PubMed Central

Leontiou, Chrysanthia A.; Hadjidaniel, Michael D.; Mina, Petros; Antoniou, Pavlos; Ioannides, Marios; Patsalis, Philippos C.

2015-01-01

Introduction Epigenetic alterations, including DNA methylation, play an important role in the regulation of gene expression. Several methods exist for evaluating DNA methylation, but bisulfite sequencing remains the gold standard by which base-pair resolution of CpG methylation is achieved. The challenge of the method is that the desired outcome (conversion of unmethylated cytosines) positively correlates with the undesired side effects (DNA degradation and inappropriate conversion), thus several commercial kits try to adjust a balance between the two. The aim of this study was to compare the performance of four bisulfite conversion kits [Premium Bisulfite kit (Diagenode), EpiTect Bisulfite kit (Qiagen), MethylEdge Bisulfite Conversion System (Promega) and BisulFlash DNA Modification kit (Epigentek)] regarding conversion efficiency, DNA degradation and conversion specificity. Methods Performance was tested by combining fully methylated and fully unmethylated λ-DNA controls in a series of spikes by means of Sanger sequencing (0%, 25%, 50% and 100% methylated spikes) and Next-Generation Sequencing (0%, 3%, 5%, 7%, 10%, 25%, 50% and 100% methylated spikes). We also studied the methylation status of two of our previously published differentially methylated regions (DMRs) at base resolution by using spikes of chorionic villus sample in whole blood. Results The kits studied showed different but comparable results regarding DNA degradation, conversion efficiency and conversion specificity. However, the best performance was observed with the MethylEdge Bisulfite Conversion System (Promega) followed by the Premium Bisulfite kit (Diagenode). The DMRs, EP6 and EP10, were confirmed to be hypermethylated in the CVS and hypomethylated in whole blood. Conclusion Our findings indicate that the MethylEdge Bisulfite Conversion System (Promega) was shown to have the best performance among the kits. In addition, the methylation level of two of our DMRs, EP6 and EP10, was confirmed. Finally, we showed that bisulfite amplicon sequencing is a suitable approach for methylation analysis of targeted regions. PMID:26247357

Application of quality by design concept to develop a dual gradient elution stability-indicating method for cloxacillin forced degradation studies using combined mixture-process variable models.

PubMed

Zhang, Xia; Hu, Changqin

2017-09-08

Penicillins are typical of complex ionic samples which likely contain large number of degradation-related impurities (DRIs) with different polarities and charge properties. It is often a challenge to develop selective and robust high performance liquid chromatography (HPLC) methods for the efficient separation of all DRIs. In this study, an analytical quality by design (AQbD) approach was proposed for stability-indicating method development of cloxacillin. The structures, retention and UV characteristics rules of penicillins and their impurities were summarized and served as useful prior knowledge. Through quality risk assessment and screen design, 3 critical process parameters (CPPs) were defined, including 2 mixture variables (MVs) and 1 process variable (PV). A combined mixture-process variable (MPV) design was conducted to evaluate the 3 CPPs simultaneously and a response surface methodology (RSM) was used to achieve the optimal experiment parameters. A dual gradient elution was performed to change buffer pH, mobile-phase type and strength simultaneously. The design spaces (DSs) was evaluated using Monte Carlo simulation to give their possibility of meeting the specifications of CQAs. A Plackett-Burman design was performed to test the robustness around the working points and to decide the normal operating ranges (NORs). Finally, validation was performed following International Conference on Harmonisation (ICH) guidelines. To our knowledge, this is the first study of using MPV design and dual gradient elution to develop HPLC methods and improve separations for complex ionic samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Methods for cellobiosan utilization

DOEpatents

Linger, Jeffrey; Beckham, Gregg T.

2017-07-11

Disclosed herein are enzymes useful for the degradation of cellobiosan in materials such a pyrolysis oils. Methods of degrading cellobiosan using enzymes or organisms expressing the same are also disclosed.

Electron and Fluorescence Microscopy of Extracellular Glucan and Aryl-Alcohol Oxidase during Wheat-Straw Degradation by Pleurotus eryngii

PubMed Central

Barrasa, J. M.; Gutiérrez, A.; Escaso, V.; Guillén, F.; Martínez, M. J.; Martínez, A. T.

1998-01-01

The ligninolytic fungus Pleurotus eryngii grown in liquid medium secreted extracellular polysaccharide (87% glucose) and the H2O2-producing enzyme aryl-alcohol oxidase (AAO). The production of both was stimulated by wheat-straw. Polyclonal antibodies against purified AAO were obtained, and a complex of glucanase and colloidal gold was prepared. With these tools, the localization of AAO and extracellular glucan in mycelium from liquid medium and straw degraded under solid-state fermentation conditions was investigated by transmission electron microscopy (TEM) and fluorescence microscopy. These studies revealed that P. eryngii produces a hyphal sheath consisting of a thin glucan layer. This sheath appeared to be involved in both mycelial adhesion to the straw cell wall during degradation and AAO immobilization on hyphal surfaces, with the latter evidenced by double labeling. AAO distribution during differential degradation of straw tissues was observed by immunofluorescence microscopy. Finally, TEM immunogold studies confirmed that AAO penetrates the plant cell wall during P. eryngii degradation of wheat straw. PMID:9435085

SUMO regulates proteasome-dependent degradation of FLASH/Casp8AP2

PubMed Central

Vennemann, Astrid; Hofmann, Thomas G.

2013-01-01

FLASH/Casp8AP2 is a huge multifunctional protein involved in multiple cellular processes, reaching from death receptor signaling to regulation of histone gene transcription and histone mRNA processing. Previous work has shown that FLASH localizes to Cajal bodies and promyelocytic leukemia (PML) bodies. However, the function of its nuclear body association remains unclear. Here we demonstrate that murine FLASH is covalently modified by SUMO at Lys residue 1792. Interestingly, ectopic expression of SUMO results in proteasome-dependent degradation of FLASH. A point mutant of FLASH with a mutated SUMO acceptor lysine residue, FLASHK1792R, is resistant to SUMO-induced degradation. Finally, we show that arsenic trioxide, a drug known to potentiate SUMO modification and degradation of PML, triggers recruitment of FLASH to PML bodies and concomitant loss of FLASH protein. Our data suggest that SUMO targets FLASH for proteasome-dependent degradation, which is associated with recruitment of FLASH to PML bodies. PMID:23673342

Urbanization, regime type and durability, and environmental degradation in Ghana.

PubMed

Adams, Samuel; Adom, Philip Kofi; Klobodu, Edem Kwame Mensah

2016-12-01

This study examines the effect of urbanization, income, trade openness, and institutional quality (i.e., regime type and durability) on environmental degradation in Ghana over the period 1965-2011. Using the bounds test approach to cointegration and the Fully Modified Phillip-Hansen (FMPH) technique, the findings show that urbanization, income, trade openness, and institutional quality have long-run cointegration with environmental degradation. Further, the results show that income, trade openness, and institutional quality are negatively associated with environmental degradation. This suggests that income, trade openness, and institutional quality enhance environmental performance. Urbanization, however, is positively related to environmental degradation. Additionally, long-run estimates conditioned on institutional quality reveal that the extent to which trade openness and urbanization enhance environmental performance is largely due to the presence of quality institutions (or democratic institutions). Finally, controlling for structural breaks, we find that trade openness, urbanization, and regime type (i.e., democracy) improve environmental performance significantly after the 1970s except for income.

Optimizing the electrical excitation of an atmospheric pressure plasma advanced oxidation process.

PubMed

Olszewski, P; Li, J F; Liu, D X; Walsh, J L

2014-08-30

The impact of pulse-modulated generation of atmospheric pressure plasma on the efficiency of organic dye degradation has been investigated. Aqueous samples of methyl orange were exposed to low temperature air plasma and the degradation efficiency was determined by absorbance spectroscopy. The plasma was driven at a constant frequency of 35kHz with a duty cycle of 25%, 50%, 75% and 100%. Relative concentrations of dissolved nitrogen oxides, pH, conductivity and the time evolution of gas phase ozone were measured to identify key parameters responsible for the changes observed in degradation efficiency. The results indicate that pulse modulation significantly improved dye degradation efficiency, with a plasma pulsed at 25% duty showing a two-fold enhancement. Additionally, pulse modulation led to a reduction in the amount of nitrate contamination added to the solution by the plasma. The results clearly demonstrate that optimization of the electrical excitation of the plasma can enhance both degradation efficiency and the final water quality. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of different oxytetracycline addition methods on its degradation behavior in soil.

PubMed

Chen, Gui-Xiu; He, Wei-Wei; Wang, Yan; Zou, Yong-De; Liang, Juan-Boo; Liao, Xin-Di; Wu, Yin-Bao

2014-05-01

The degradation behavior of veterinary antibiotics in soil is commonly studied using the following methods of adding antibiotics to the soil: (i) adding manure collected from animals fed with a diet containing antibiotics, (ii) adding antibiotic-free animal manure spiked with antibiotics and (iii) directly adding antibiotics. No research simultaneously comparing different antibiotic addition methods was found. Oxytetracycline (OTC) was used as a model antibiotic to compare the effect of the three commonly used antibiotic addition methods on OTC degradation behavior in soil. The three treatment methods have similar trends, though OTC degradation half-lives show the following significant differences (P<0.05): manure from swine fed OTC (treatment A)

Method of degrading pollutants in soil

DOEpatents

Hazen, Terry C.; Lopez-De-Victoria, Geralyne

1994-01-01

A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

Real-time PCR for rapidly detecting aniline-degrading bacteria in activated sludge.

PubMed

Kayashima, Takakazu; Suzuki, Hisako; Maeda, Toshinari; Ogawa, Hiroaki I

2013-05-01

We developed a detection method that uses quantitative real-time PCR (qPCR) and the TaqMan system to easily and rapidly assess the population of aniline-degrading bacteria in activated sludge prior to conducting a biodegradability test on a chemical compound. A primer and probe set for qPCR was designed by a multiple alignment of conserved amino acid sequences encoding the large (α) subunit of aniline dioxygenase. PCR amplification tests showed that the designed primer and probe set targeted aniline-degrading strains such as Acidovorax sp., Gordonia sp., Rhodococcus sp., and Pseudomonas putida, thereby suggesting that the developed method can detect a wide variety of aniline-degrading bacteria. There was a strong correlation between the relative copy number of the α-aniline dioxygenase gene in activated sludge obtained with the developed qPCR method and the number of aniline-degrading bacteria measured by the Most Probable Number method, which is the conventional method, and a good correlation with the lag time of the BOD curve for aniline degradation produced by the biodegradability test in activated sludge samples collected from eight different wastewater treatment plants in Japan. The developed method will be valuable for the rapid and accurate evaluation of the activity of inocula prior to conducting a ready biodegradability test. Copyright © 2013 Elsevier Ltd. All rights reserved.

Degradation trend estimation of slewing bearing based on LSSVM model

NASA Astrophysics Data System (ADS)

Lu, Chao; Chen, Jie; Hong, Rongjing; Feng, Yang; Li, Yuanyuan

2016-08-01

A novel prediction method is proposed based on least squares support vector machine (LSSVM) to estimate the slewing bearing's degradation trend with small sample data. This method chooses the vibration signal which contains rich state information as the object of the study. Principal component analysis (PCA) was applied to fuse multi-feature vectors which could reflect the health state of slewing bearing, such as root mean square, kurtosis, wavelet energy entropy, and intrinsic mode function (IMF) energy. The degradation indicator fused by PCA can reflect the degradation more comprehensively and effectively. Then the degradation trend of slewing bearing was predicted by using the LSSVM model optimized by particle swarm optimization (PSO). The proposed method was demonstrated to be more accurate and effective by the whole life experiment of slewing bearing. Therefore, it can be applied in engineering practice.

Combined process of electrocoagulation and photocatalytic degradation for the treatment of olive washing wastewater.

PubMed

Ates, Hasan; Dizge, Nadir; Yatmaz, H Cengiz

2017-01-01

In this study, an electrocoagulation reactor (ECR) and photocatalytic reactor (PCR) were tested to understand the performance of combined electrocoagulation and photocatalytic-degradation of olive washing wastewater (OWW). The effects of initial pH (6.0, 6.9, 8.0, 9.0), applied voltage (10.0, 12.5, 15.0 V), and operating time (30, 60, 90, 120 min) were investigated in the electrocoagulation reactor when aluminum electrodes were used as both anode and cathode. The pH, conductivity, color, chemical oxygen demand (COD), and phenol were measured versus time to determine the efficiency of the ECR and PCR process. It was observed that electrocoagulation as a single treatment process supplied the COD removal of 62.5%, color removal of 98.1%, and total phenol removal of 87% at optimum conditions as pH 6.9, applied voltage of 12.5 V, and operating time of 120 min. Moreover, final pH and conductivity were 7.7 and 980 μS/cm, respectively. On the other hand, the effect of semiconductor catalyst type (TiO 2 and ZnO) and loading (1, 2, 3 g/L) were tested using PCR as a stand-alone technique. It was found that photocatalytic degradation as a single treatment process when using 1 g/L ZnO achieved the COD removal of 46%, color removal of 99% with a total phenol removal of 41% at optimum conditions. Final pH and conductivity were 6.2 and 915 μS/cm, respectively. Among semiconductor catalysts, TiO 2 and ZnO performed identical efficiencies for both COD and total phenol removal. Moreover, combination in which electrochemical degradation was employed as a pre-treatment to the photocatalytic degradation process obtained high COD removal of 88% and total phenol, as well as color removal of 100% for the OWW. The electrochemical treatment alone was not effective, but in combination with the photocatalytic process, led to a high-quality effluent. Finally, sludge collected from the electrocoagulation process was characterized by attenuated total reflection Fourier transform infrared and X-ray powder diffraction analyses.

Digital Simulation Of Precise Sensor Degradations Including Non-Linearities And Shift Variance

NASA Astrophysics Data System (ADS)

Kornfeld, Gertrude H.

1987-09-01

Realistic atmospheric and Forward Looking Infrared Radiometer (FLIR) degradations were digitally simulated. Inputs to the routine are environmental observables and the FLIR specifications. It was possible to achieve realism in the thermal domain within acceptable computer time and random access memory (RAM) requirements because a shift variant recursive convolution algorithm that well describes thermal properties was invented and because each picture element (pixel) has radiative temperature, a materials parameter and range and altitude information. The computer generation steps start with the image synthesis of an undegraded scene. Atmospheric and sensor degradation follow. The final result is a realistic representation of an image seen on the display of a specific FLIR.

Improved radioimmunotherapy of hematologic malignancies. Final technical report

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

Press, O.W.

1996-08-15

Experiments were performed to study the rates of endocytosis, intracellular routing, and metabolic degradation of radiolabeled monoclonal antibodies targeting tumor-associated antigens on human leukemia and lymphoma cells. An attempt was made to examine in vivo the effects of lysosomotropic amines and thioamides on the retention of radiolabeled monoclonal antibodies by tumor cells. Experiments also examined the impact of newer radioiodination techniques on the metabolic degradation of radioiodinated antibodies, and on the radioimmunoscintigraphy and radioimmunotherapy of neoplasms. The endocytosis, intracellular routing, and degradation of radioimmunoconjugates prepared with I-131, In-111, and Y-90 were compared. The utility of radioimmunoconjugates targeting oncogene products formore » the radioimmunotherapy and radioimmunoscintigraphy of cancer was investigated.« less

Materials Degradation and Detection (MD2): Deep Dive Final Report

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

McCloy, John S.; Montgomery, Robert O.; Ramuhalli, Pradeep

2013-02-01

An effort is underway at Pacific Northwest National Laboratory (PNNL) to develop a fundamental and general framework to foster the science and technology needed to support real-time monitoring of early degradation in materials used in the production of nuclear power. The development of such a capability would represent a timely solution to the mounting issues operators face with materials degradation in nuclear power plants. The envisioned framework consists of three primary and interconnected “thrust” areas including 1) microstructural science, 2) behavior assessment, and 3) monitoring and predictive capabilities. A brief state-of-the-art assessment for each of these core technology areas ismore » discussed in the paper.« less

Degradation of ketoprofen by sulfate radical-based advanced oxidation processes: Kinetics, mechanisms, and effects of natural water matrices.

PubMed

Feng, Yiping; Song, Qingyun; Lv, Wenying; Liu, Guoguang

2017-12-01

Ketoprofen (KET) is a mostly used nonsteroidal anti-inflammatory drug that has been frequently detected in wastewater effluents and surface waters. In this study, we investigated the degradation of KET by sulfate radical (SO 4 - ) based advanced oxidation processes (SR-AOPs) in aqueous solution. The degradation kinetics, mechanisms, and effects of natural water matrices on thermally activated persulfate (TAP) oxidation of KET were systematically investigated. Increasing the temperature and persulfate (PS) concentrations greatly enhanced the degradation of KET. KET degradation is pH-dependent with an optimum pH of 5.0. Reactions in the presence of radical quenchers revealed the dominant role of SO 4 - in oxidizing KET. Water matrix significantly influenced the degradation of KET. The common inorganic anions present in natural waters exhibited inhibitory effect on KET degradation, and the inhibition followed the order of Cl -  > CO 3 2-  > HCO 3 -  > NO 3 - ; however, no significant inhibition of KET degradation was observed in the presence of Ca 2+ and Mg 2+ cations. The presence of natural organic matter (NOM) suppressed KET degradation, and the suppression increased as NOM concentration increase. Products identification and mineralization experiments revealed that KET and its degradation intermediates were finally transformed into CO 2 and H 2 O. The results of this study indicated that applying SR-AOPs for the remediation of KET contaminated water matrix is technically possible. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel accelerated oxidative stability screening method for pharmaceutical solids.

PubMed

Zhu, Donghua Alan; Zhang, Geoff G Z; George, Karen L S T; Zhou, Deliang

2011-08-01

Despite the fact that oxidation is the second most frequent degradation pathway for pharmaceuticals, means of evaluating the oxidative stability of pharmaceutical solids, especially effective stress testing, are still lacking. This paper describes a novel experimental method for peroxide-mediated oxidative stress testing on pharmaceutical solids. The method utilizes urea-hydrogen peroxide, a molecular complex that undergoes solid-state decomposition and releases hydrogen peroxide vapor at elevated temperatures (e.g., 30°C), as a source of peroxide. The experimental setting for this method is simple, convenient, and can be operated routinely in most laboratories. The fundamental parameter of the system, that is, hydrogen peroxide vapor pressure, was determined using a modified spectrophotometric method. The feasibility and utility of the proposed method in solid form selection have been demonstrated using various solid forms of ephedrine. No degradation was detected for ephedrine hydrochloride after exposure to the hydrogen peroxide vapor for 2 weeks, whereas both anhydrate and hemihydrate free base forms degraded rapidly under the test conditions. In addition, both the anhydrate and the hemihydrate free base degraded faster when exposed to hydrogen peroxide vapor at 30°C under dry condition than at 30°C/75% relative humidity (RH). A new degradation product was also observed under the drier condition. The proposed method provides more relevant screening conditions for solid dosage forms, and is useful in selecting optimal solid form(s), determining potential degradation products, and formulation screening during development. Copyright © 2011 Wiley-Liss, Inc.

Application of a new integrated sediment quality assessment method to Huelva estuary and its littoral of influence (Southwestern Spain).

PubMed

Rosado, Daniel; Usero, José; Morillo, José

2015-09-15

A new integrated sediment quality assessment method composed of several assays (particle size profile, total metal content, protease K extraction, total organic carbon, toxicity bioassay with Photobacterium phosphoreum and macrobenthic community alteration) that provides a single result, the environmental degradation index (EDI), has been developed. The new method was tested on the Huelva estuary (southwest of Spain), a highly polluted area where metals dissolved in the water of the Tinto and Odiel rivers precipitate after flowing through the Iberian Pyrite Belt, one of the largest metallogenic areas of massive sulphide deposits in the world. The proposed method satisfactorily was able to reflect different degrees of pollution on the environmental degradation index. Thus, EDI categorized littoral samples as slightly degraded and all the Tinto and some of the Odiel as very highly degraded, emphasizing the lower zone of the Tinto estuary as the most deeply degraded of the entire study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Validation of UV spectrophotometric methods for the determination of dothiepin hydrochloride in pharmaceutical dosage form and stress degradation studies

NASA Astrophysics Data System (ADS)

Abdulrahman, Sameer A. M.; Basavaiah, K.; Cijo, M. X.; Vinay, K. B.

2012-11-01

Spectrophotometric methods have been developed for the determination of dothiepin hydrochloride (DOTH) in both pure and tablet dosage form and their limits of detection and quantification have been evaluated. The methods are based on the measurement of the absorbance of a DOTH solution either in 0.1 N HCl at 229 nm (method A) or in methanol at 231 nm (method B). Beer's law is obeyed over a concentration range of 1-16 μg/ml DOTH for both methods. Molar absorptivity values are calculated to be 2.48 × 104 and 2.42 × 104 l/(mol × cm) with Sandell sensitivity values of 0.0134 and 0.0137 μg/cm2 for methods A and B, respectively. The degradation behavior of DOTH was investigated under different stress conditions such as acid hydrolysis, alkaline hydrolysis, water hydrolysis, oxidation, dry heat treatment, and UV-degradation. The drug undergoes significant degradation under oxidative conditions only.

Effect of drying temperatures on structural performance and photocatalytic activity of BiOCl synthesized by a soft chemical method

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

Guang, Lu, E-mail: lu_g@163.com; Hui, Wang; Xuejun, Zou

2016-07-15

A group of BiOCl photocatalysts with different drying temperatures were prepared by a soft chemical method. The effects of drying temperatures on the crystalline phase, morphology, surface area and optical property of as-prepared samples were investigated in detail by XRD, SEM, N{sub 2} absorption–desorption and DRS. Moreover, their photocatalytic activities on the degradation of rhodamine B were evaluated under visible light irradiation. It was found that the sample dried at 120 °C had the best photocatalytic activity, which was mainly attributed to the highest exposing proportion of {001} facets correspond to BiOCl, largest BET and minimum bandgap. The degradation mechanismmore » was explored that superoxide radicals were mainly contributed to the degradation of chromophore, however, holes and hydroxyl were mainly contributed to the photo degradation. Moreover, holes and hydroxyl dominated the degradation of RhB. - Graphical abstract: Holes, hydroxyl and superoxide radicals can attribute to the degradation process but take different degradation pathways. Superoxide radicals mainly contribute to the degradation of chromophore, however, holes and hydroxyl mainly contribute to the photo degradation. Display Omitted - Highlights: • BiOCl nanosheets were prepared by a soft chemical method. • Effect of drying temperatures on as-prepared BiOCl samples was studied. • The highest removal efficiency of RhB was obtained over the sample dried at 120 °C.« less

Frequency Compounded Imaging with a High-Frequency Dual Element Transducer

PubMed Central

Chang, Jin Ho; Kim, Hyung Ham; Lee, Jungwoo; Shung, K. Kirk

2014-01-01

This paper proposes a frequency compounding method to reduce speckle interferences, where a concentric annular type high-frequency dual element transducer is used to broaden the bandwidth of an imaging system. In frequency compounding methods, frequency division is carried out to obtain sub-band images containing uncorrelated speckles, which sacrifices axial resolution. Therefore, frequency compounding often deteriorates the target-detecting capability, quantified by the total signal-to-noise ratio (SNR), when the speckle’s SNR (SSNR) is not improved as much as the degraded axial resolution. However, this could be avoided if the effective bandwidth required for frequency compounding is increased. The primary goal of the proposed approach, hence, is to improve SSNR by a factor of two under the condition where axial resolution is degraded by a factor of less than two, which indicates the total SNR improvement to higher than 40% compared to that of an original image. Since the method here employs a dual element transducer operating at 20 and 40 MHz, the effective bandwidth necessary for frequency compounding becomes broadened. By dividing each spectrum of RF samples from both elements into two sub-bands, this method eventually enables four sets of the sub-band samples to contain uncorrelated speckles. This causes the axial resolution to be reduced by a factor of as low as 1.85, which means that this method would improve total SNR by at least 47 %. An in vitro experiment on an excised pig eye was performed to validate the proposed approach, and the results showed that the SSNR was improved from 2.081±0.365 in the original image to 4.206±0.635 in the final compounding image. PMID:19914674

Frequency compounded imaging with a high-frequency dual element transducer.

PubMed

Chang, Jin Ho; Kim, Hyung Ham; Lee, Jungwoo; Shung, K Kirk

2010-04-01

This paper proposes a frequency compounding method to reduce speckle interferences, where a concentric annular type high-frequency dual element transducer is used to broaden the bandwidth of an imaging system. In frequency compounding methods, frequency division is carried out to obtain sub-band images containing uncorrelated speckles, which sacrifices axial resolution. Therefore, frequency compounding often deteriorates the target-detecting capability, quantified by the total signal-to-noise ratio (SNR), when the speckle's SNR (SSNR) is not improved as much as the degraded axial resolution. However, this could be avoided if the effective bandwidth required for frequency compounding is increased. The primary goal of the proposed approach, hence, is to improve SSNR by a factor of two under the condition where axial resolution is degraded by a factor of less than two, which indicates the total SNR improvement to higher than 40% compared to that of an original image. Since the method here employs a dual element transducer operating at 20 and 40MHz, the effective bandwidth necessary for frequency compounding becomes broadened. By dividing each spectrum of RF samples from both elements into two sub-bands, this method eventually enables four sets of the sub-band samples to contain uncorrelated speckles. This causes the axial resolution to be reduced by a factor of as low as 1.85, which means that this method would improve total SNR by at least 47%. An in vitro experiment on an excised pig eye was performed to validate the proposed approach, and the results showed that the SSNR was improved from 2.081+/-0.365 in the original image to 4.206+/-0.635 in the final compounding image. Copyright 2009 Elsevier B.V. All rights reserved.

Stacked dielectric elastomer actuator (SDEA): casting process, modeling and active vibration isolation

NASA Astrophysics Data System (ADS)

Li, Zhuoyuan; Sheng, Meiping; Wang, Minqing; Dong, Pengfei; Li, Bo; Chen, Hualing

2018-07-01

In this paper, a novel fabrication process of stacked dielectric elastomer actuator (SDEA) is developed based on casting process and elastomeric electrode. The so-fabricated SDEA benefits the advantages of homogenous and reproducible properties as well as little performance degradation after one-year use. A coupling model of SDEA is established by taking into consideration of the elastomeric electrode and the calculated results agree with the experiments. Based on the model, we attain the method to optimize the SDEA’s parameters. Finally, the SDEA is used as an isolator in active vibration isolation system to verify the feasibility in dynamic application. And the experiment results show a great prospect for SDEA in such application.

Approaches to Neural Tissue Engineering Using Scaffolds for Drug Delivery

PubMed Central

Willerth, Stephanie M.; Sakiyama-Elbert, Shelly E.

2007-01-01

This review seeks to give an overview of the current approaches to drug delivery from scaffolds for neural tissue engineering applications. The challenges presented by attempting to replicate the three types of nervous tissue (brain, spinal cord, and peripheral nerve) are summarized. Potential scaffold materials (both synthetic and natural) and target drugs are discussed with the benefits and drawbacks given. Finally, common methods of drug delivery, including degradable/diffusion-based delivery systems, affinity-based delivery systems, immobilized drug delivery systems, and electrically controlled drug delivery systems, are examined and critiqued. Based on the current body of work, suggestions for future directions of research in the field of neural tissue engineering are presented. PMID:17482308

Poly(fumaric-co-sebacic anhydride). A degradation study as evaluated by FTIR, DSC, GPC and X-ray diffraction.

PubMed

Santos, C A; Freedman, B D; Leach, K J; Press, D L; Scarpulla, M; Mathiowitz, E

1999-06-28

The degradation of three poly(fumaric-co-sebacic anhydride) [P(FA:SA)] copolymers is examined in a composition of microspheres made by the hot melt encapsulation process. The emergence of low molecular weight oligomers occurs during degradation of the copolymer microspheres, as evidenced by a variety of characterization methods. Characterization was conducted to determine the extent of degradation of the polyanhydride microspheres using Fourier-transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and X-ray diffraction. It is demonstrated that degradation of P(FA:SA) is greatly accelerated at basic pH, yet there is little difference between degradation in neutral and acidic buffers. A good correlation exists between the results of each characterization method, which allows a better understanding of the degradation process and the resulting formation of low molecular weight oligomers in poly(fumaric-co-sebacic anhydride).

Application of plasma electrolysis method for simultaneous phenol and Cr(VI) wastewater degradation using Na2SO4 electrolyte

NASA Astrophysics Data System (ADS)

Harianti, Aulia Rahmi; Saksono, Nelson

2017-11-01

Phenol and Cr (VI) are two types of wastewater known as dangerous and difficult to degrade. Through this study, phenol and Cr (VI) metal wastewater were degraded simultaneously using plasma electrolysis method by reactive species, •OH and H•. The variation of anode depth and position of plasma formation as independent variables correlated with yield of hydroxyl radical, percentage of phenol and Cr (VI) degradation, and specific energy. Within 30 minutes, phenol was degraded to 98.4% and Cr (VI) was degraded to 93.35% with 171.05 kJ/mmol in specific energy, and 174.53 ppm in COD. The optimum condition was obtained in anodic plasma and 1.5 cm in anode depth. The highest degradation percentage of phenol and Cr (VI) were 99.79% and 97.33% achieved during 180 minutes of plasma electrolysis process.

UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.

PubMed

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

2012-10-01

The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. 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 irinotecan hydrochloride in pharmaceutical dosage forms.

Stability-Indicating HPTLC Method for Studying Stress Degradation Behavior of Sulbutiamine HCl

PubMed Central

Farid, Nehal F.; Abdelwahab, Nada S.

2016-01-01

Sulbutiamine (SUL) is an ester of thiazides with neurotropic action. A new stability indicating HPTLC method has been developed and validated for the determination of SUL in the presence of different degradation products. The drug was subjected to different stress conditions following ICH strategy such as hydrolytic degradation (neutral, alkaline and acidic hydrolysis), oxidation, photodegradation and dry heat degradation. The drug demonstrated degradation under all decomposition conditions except neutral hydrolysis and dry heat, where the drug was completely degraded with 0.1 N NaOH, 1 N HCl and 30% H2O2 while it was partially degradaed by 0.1 N HCl, 3% H2O2 and UV light. Structure elucidation of the resulting degradation products was performed using ESI-Q-MS–MS. A well-defined peak for SUL was obtained at Rf = 0.46 and was completely separated from all obtained degradation products. Chromatographic separation was carried out on HPTLC aluminum plates precoated with silica gel 60 F254 using acetone–methylene chloride–ammonia buffer (pH 8.5 ± 0.2) (7:3:0.5, v/v) as a developing system. Densitometric scanning of the separated peaks was performed at 254 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed method. The method was validated with respect to USP guidelines regarding accuracy, precision, specificity, robustness and ruggedness. Good correlation coefficients were achieved in the range of 0.4–5.0 µg/band, and the limit of detection and limit of quantitation were found to be 0.11 and 0.33 µg/band, respectively. The utility of the suggested method was verified by application to Arcalion forte® tablets where no interference from additives was found. PMID:26759487

Solar cell radiation handbook

NASA Technical Reports Server (NTRS)

Carter, J. R., Jr.; Tada, H. Y.

1973-01-01

A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

Pyrolysis Strategies for Effective Utilization of Lignocellulosic and Algal Biomass

NASA Astrophysics Data System (ADS)

Maddi, Balakrishna

Pyrolysis is a processing technique involving thermal degradation of biomass in the absence of oxygen. The bio-oils obtained following the condensation of the pyrolysis vapors form a convenient starting point for valorizing the major components of lignocellulosic as well as algal biomass feed stocks for the production of fuels and value-added chemicals. Pyrolysis can be implemented on whole biomass or on residues left behind following standard fractionation methods. Microalgae and oil seeds predominantly consist of protein, carbohydrate and triglycerides, whereas lignocellulose is composed of carbohydrates (cellulose and hemicellulose) and lignin. The differences in the major components of these two types of biomass will necessitate different pyrolysis strategies to derive the optimal benefits from the resulting bio-oils. In this thesis, novel pyrolysis strategies were developed that enable efficient utilization of the bio-oils (and/or their vapors) from lignocellulose, algae, as well as oil seed feed stocks. With lignocellulosic feed stocks, pyrolysis of whole biomass as well as the lignin residue left behind following well-established pretreatment and saccharification (i.e., depolymerization of cellulose and hemicellulose to their monomeric-sugars) of the biomass was studied with and without catalysts. Following this, pyrolysis of (lipid-deficient) algae and lignocellulosic feed stocks, under similar reactor conditions, was performed for comparison of product (bio-oil, gas and bio-char) yields and composition. In spite of major differences in component bio-polymers, feedstock properties relevant to thermo-chemical conversions, such as overall C, H and O-content, C/O and H/C molar ratio as well as calorific values, were found to be similar for algae and lignocellulosic material. Bio-oil yields from algae and some lignocellulosic materials were similar; however, algal bio-oils were compositionally different and contained several N-compounds (most likely from protein degradation). Algal bio-char also had a significantly higher N-content. Overall, our results suggest that it is feasible to convert algal cultures deficient in lipids, such as nuisance algae obtained from natural blooms, into liquid fuels by thermochemical methods. Next, pyrolysis characteristics of each of the major components present in lignocellulosic as well as algal biomass were studied independently in a thermo-gravimetric analyzer, using model compounds. From those studies, we have established that, with algae and oil seed feed stocks, triglycerides degrade at distinctly higher temperatures (T>350 C) compared to both protein and carbohydrate fractions (T ~ 250-350 C). Similar trend was not seen for lignocellulosic biomass, where degradation temperature interval of lignin overlapped with that of carbohydrates. This unique trend observed for algal biomass (and oil seeds) can be exploited in multiple ways. First, it permits to separately collect high value triglyceride degradation products not contaminated with N-compounds from protein and oxygenates from carbohydrates; this observation formed the basis of a novel "pyrolytic fractionation technique" developed in this thesis. Second, it led to the development of a new and simple analytical method for rapid estimation of the triglyceride content of oleaginous feed stocks. Pyrolytic fractionation is a two-step pyrolysis approach that can be implemented for oleaginous feed stocks (algae and oil-seeds) to separately recover triglyceride degradation products as a "high-quality" bio-oil fraction. The first step is a low-temperature pyrolysis (T ~ 300-320 C) to produce bio-oils from degradation of protein and carbohydrate fractions. Solid residues left behind can subsequently be subjected to a second higher temperature pyrolysis (T ~ 420-430 C) to volatilize and/or degrade triglycerides to produce fatty acids and their derivatives (such as mono-, di- and tri-glycerides) and long chain hydrocarbons. Proof-of-concept micro-pyrolyser (Pyroprobe) and lab-scale fixed-bed experiments were performed using oleaginous algae (Chlorella Sp.) to establish pyrolytic fractionation technique and also to determine the yields of triglyceride-specific bio-oils. As expected, triglyceride-specific bio-oils have hydrocarbons and free fatty acids that were nearly free of water, organic acids and carbohydrate degradation products. Another unique feature of the fractional pyrolysis method is that it allows upgrading of the triglyceride-specific bio-oil vapors via in situ gas-phase hydro-deoxygenation to drop-in fuels (hydrocarbons), without the need to condense the vapors. Similarly, these vapors can also be converted to other value-added products such as fatty acid methyl esters and amides though efficient catalytic and non-catalytic in situ gas-phase conversion methods. Energy requirements for this new pyrolytic fractionation method were also assessed, using energy estimates for the individual steps obtained via differential scanning calorimetry experiments. A comparison of these energy needs against those of alternative thermal processing methods of algae (hydro-thermal processing) proposed in the literature established the viability of this new method. Finally, a new TGA-based analytical method was developed in this thesis for rapid quantification of the triglyceride content of oleaginous feed stocks, by exploiting the non-overlapping thermal degradation range of triglycerides and the other major components.

Effects of the Particulate Matter₂.₅ (PM₂.₅) on Lipoprotein Metabolism, Uptake and Degradation, and Embryo Toxicity.

PubMed

Kim, Jae-Yong; Lee, Eun-Young; Choi, Inho; Kim, Jihoe; Cho, Kyung-Hyun

2015-12-01

Particulate matter2.5 (PM2.5) is notorious for its strong toxic effects on the cardiovascular, skin, nervous, and reproduction systems. However, the molecular mechanism by which PM2.5 aggravates disease progression is poorly understood, especially in a water-soluble state. In the current study, we investigated the putative physiological effects of aqueous PM2.5 solution on lipoprotein metabolism. Collected PM2.5 from Seoul, Korea was dissolved in water, and the water extract (final 3 and 30 ppm) was treated to human serum lipoproteins, macrophages, and dermal cells. PM2.5 extract resulted in degradation and aggregation of high-density lipoprotein (HDL) as well as low-density lipoprotein (LDL); apoA-I in HDL aggregated and apo-B in LDL disappeared. PM2.5 treatment (final 30 ppm) also induced cellular uptake of oxidized LDL (oxLDL) into macrophages, especially in the presence of fructose (final 50 mM). Uptake of oxLDL along with production of reactive oxygen species was accelerated by PM2.5 solution in a dose-dependent manner. Further, PM2.5 solution caused cellular senescence in human dermal fibroblast cells. Microinjection of PM2.5 solution into zebrafish embryos induced severe mortality accompanied by impairment of skeletal development. In conclusion, water extract of PM2.5 induced oxidative stress as a precursor to cardiovascular toxicity, skin cell senescence, and embryonic toxicity via aggregation and proteolytic degradation of serum lipoproteins.

Effects of the Particulate Matter2.5 (PM2.5) on Lipoprotein Metabolism, Uptake and Degradation, and Embryo Toxicity

PubMed Central

Kim, Jae-Yong; Lee, Eun-Young; Choi, Inho; Kim, Jihoe; Cho, Kyung-Hyun

2015-01-01

Particulate matter2.5 (PM2.5) is notorious for its strong toxic effects on the cardiovascular, skin, nervous, and reproduction systems. However, the molecular mechanism by which PM2.5 aggravates disease progression is poorly understood, especially in a water-soluble state. In the current study, we investigated the putative physiological effects of aqueous PM2.5 solution on lipoprotein metabolism. Collected PM2.5 from Seoul, Korea was dissolved in water, and the water extract (final 3 and 30 ppm) was treated to human serum lipoproteins, macrophages, and dermal cells. PM2.5 extract resulted in degradation and aggregation of high-density lipoprotein (HDL) as well as low-density lipoprotein (LDL); apoA-I in HDL aggregated and apo-B in LDL disappeared. PM2.5 treatment (final 30 ppm) also induced cellular uptake of oxidized LDL (oxLDL) into macrophages, especially in the presence of fructose (final 50 mM). Uptake of oxLDL along with production of reactive oxygen species was accelerated by PM2.5 solution in a dose-dependent manner. Further, PM2.5 solution caused cellular senescence in human dermal fibroblast cells. Microinjection of PM2.5 solution into zebrafish embryos induced severe mortality accompanied by impairment of skeletal development. In conclusion, water extract of PM2.5 induced oxidative stress as a precursor to cardiovascular toxicity, skin cell senescence, and embryonic toxicity via aggregation and proteolytic degradation of serum lipoproteins. PMID:26615830

A scientific and statistical analysis of accelerated aging for pharmaceuticals. Part 1: accuracy of fitting methods.

PubMed

Waterman, Kenneth C; Swanson, Jon T; Lippold, Blake L

2014-10-01

Three competing mathematical fitting models (a point-by-point estimation method, a linear fit method, and an isoconversion method) of chemical stability (related substance growth) when using high temperature data to predict room temperature shelf-life were employed in a detailed comparison. In each case, complex degradant formation behavior was analyzed by both exponential and linear forms of the Arrhenius equation. A hypothetical reaction was used where a drug (A) degrades to a primary degradant (B), which in turn degrades to a secondary degradation product (C). Calculated data with the fitting models were compared with the projected room-temperature shelf-lives of B and C, using one to four time points (in addition to the origin) for each of three accelerated temperatures. Isoconversion methods were found to provide more accurate estimates of shelf-life at ambient conditions. Of the methods for estimating isoconversion, bracketing the specification limit at each condition produced the best estimates and was considerably more accurate than when extrapolation was required. Good estimates of isoconversion produced similar shelf-life estimates fitting either linear or nonlinear forms of the Arrhenius equation, whereas poor isoconversion estimates favored one method or the other depending on which condition was most in error. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

[Purification, characterization and application of ε-poly-L. lysine- degrading enzyme from Streptomyces sp. M-Z18 ].

PubMed

Liu, Qingrui; Chen, Xusheng; Zeng, Xin; Han, Dai; Mao, Zhonggui

2014-09-04

[OBJECTIVE] The ε-poly-L-lysine-degrading enzyme (Pld) derived from Streptomyces sp. M-Z18 was purified and characterized. Furthermore, Pld was used to produce the low polymerization of ε-poly-L-lysine (ε-PL). [METHODS] Pld was purified to electrophoretical homogeneity through HiTrapTM Butyl HP hydrophobic chromatography after pretreated by ultrasonic and NaSCN dissolving. Subsequently, enzymatic characteristics, kinetic parameters and the time profile of ε-PL degradation by the purified Pld were studied. Meanwhile, we examined the effect of ε-PL with different degrees of polymerization on the minimal inhibitory concentration of bacteria and fungi. [RESULTS] Pld was purified to homogeneity with a final fold of 80.4 and an overall yield of 59.3%. The optimal temperature and pH for the purified Pld were 370C and 7. 0, respectively. Moreover, the Km with L-lysyl-p-nitroanilide as substrate was calculated to be 0. 621 mmol/L, and the Vmax was 701. 16 nmol/min.mg. Pld was stable in the range of pH 7. 0 - 10. 0, and temperature up to 500 C, respectively. Time profile of ε-PL degradation by the purified Pld indicated that Pld catalyzed endo-type degradation of ε- PL. The experiments of minimal inhibitory showed that ε-PL with high degree of polymerization (30 - 35) had a superior antibacterial effect on bacteria and the low degree of polymerization ε-PL (8 -20) had a better antibacterial effect on yeasts. However, ε-PL with various degrees of polymerization had a poor antibacterial effect on mould. [ CONCLUSION] The present result showed that an endo-type Pld from ε-PL-producing strain was purified. Meanwhile, it is proved that ε-PL with different degrees of polymerization have exhibited significant different antibacterial effects on microorganism.

Fatigue Analysis of Notched Laminates: A Time-Efficient Macro-Mechanical Approach

NASA Technical Reports Server (NTRS)

Naghipour, P.; Pineda, E. J.; Bednarcyk, B. A.; Arnold, S. M.; Waas, A. M.

2016-01-01

A coupled transversely isotropic deformation and damage fatigue model is implemented within the finite element method and was utilized along with a static progressive damage model to predict the fatigue life, stiffness degradation as a function of number of cycles, and post-fatigue tension and compression response of notched, multidirectional laminates. Initially, the material parameters for the fatigue model were obtained utilizing micromechanics simulations and the provided [0], [90] and [plus or minus 45] experimental composite laminate S-N (stress-cycle) data. Within the fatigue damage model, the transverse and shear properties of the plies were degraded with an isotropic scalar damage variable. The damage in the longitudinal (fiber) ply direction was suppressed, and only the strength of the fiber was degraded as a function of fatigue cycles. A maximum strain criterion was used to capture the failure in each element, and once this criterion was satisfied, the longitudinal stiffness of the element was decreased by a factor of 10 (sup 4). The resulting, degraded properties were then used to calculate the new stress state. This procedure was repeated until final failure of the composite laminate was achieved or a specified number of cycles reached. For post-fatigue tension and compression behavior, four internal state variables were used to control the damage and failure. The predictive capability of the above-mentioned approach was assessed by performing blind predictions of the notched multidirectional IM7/977-3 composite laminates response under fatigue and post-fatigue tensile and compressive loading, followed by a recalibration phase. Although three different multidirectional laminates were analyzed in the course of this study, only detailed results (i.e., stiffness degradation and post-fatigue stress-train curves as well as damage evolution states for a single laminate ([30/60/90/minus 30/minus 60] (sub 2s)) are discussed in detail here.

Mechanisms of microbial destabilization of soil C shifts over decades of warming

NASA Astrophysics Data System (ADS)

DeAngelis, K.; Pold, G.; Chowdhury, P. R.; Schnabel, J.; Grandy, S.; Melillo, J. M.

2017-12-01

Microbes are major actors in regulating the earth's biogeochemical cycles, with temperature-sensitive microbial tradeoffs improving ecosystem biogeochemical models. Meanwhile, the Earth's climate is changing, with decades of warming undercutting the ability of soil to store carbon. Our work explores trends of 26 years of experimental warming in temperate deciduous forest soils, which is associated with cycles of soil carbon degradation punctuated by periods of changes in soil microbial dynamics. Using a combination of biogeochemistry and molecular analytical methods, we explore the hypotheses that substrate availability, community structure, altered temperature sensitivity of microbial turnover-growth efficiency tradeoff, and microbial evolution are responsible for observations of accelerated degradation of soil carbon over time. Amplicon sequencing of microbial communities suggests a small role of changing microbial community composition over decades of warming, but a sustained suppression of fungal biomass is accompanied by increased biomass of Actinobacteria, Actinobacteria, Alphaproteobacteria, Verrucomicrobia and Planctomycetes. Substrate availability plays an important role in microbial dynamics, with depleted labile carbon in the first decade and depleted lignin in the second decade. Increased lignin-degrading enzyme activity supports the suggestion that lignin-like organic matter is an important substrate in chronically warmed soils. Metatranscriptomics data support the suggestion that increased turnover is associated with long-term warming, with metagenomic signals of increased carbohydrate-degrading enzymes in the organic horizon but decreased in the mineral soils. Finally, traits analysis of over 200 cultivated isolates of bacterial species from heated and control soils suggests an expanded ability for degradation of cellulose and hemicellulose but not chitin, supporting the hypothesis that long-term warming is exerting evolutionary pressure on microbial species. Together, these data suggest that after decades of warming both direct kinetic effects and indirect effects of altered substrate availability are affecting microbial ecology and evolution in ways that conspire to destabilize soil organic matter.

Detecting dryland degradation through the use of Time Series Segmentation and Residual Trend analysis (TSS-RESTREND)

NASA Astrophysics Data System (ADS)

Burrell, A. L.; Evans, J. P.; Liu, Y.

2017-12-01

Dryland degradation is an issue of international significance as dryland regions play a substantial role in global food production. Remotely sensed data provide the only long term, large scale record of changes within dryland ecosystems. The Residual Trend, or RESTREND, method is applied to satellite observations to detect dryland degradation. Whilst effective in most cases, it has been shown that the RESTREND method can fail to identify degraded pixels if the relationship between vegetation and precipitation has broken-down as a result of severe or rapid degradation. This study presents an extended version of the RESTREND methodology that incorporates the Breaks For Additive Seasonal and Trend method to identify step changes in the time series that are related to significant structural changes in the ecosystem, e.g. land use changes. When applied to Australia, this new methodology, termed Time Series Segmentation and Residual Trend analysis (TSS-RESTREND), was able to detect degradation in 5.25% of pixels compared to only 2.0% for RESTREND alone. This modified methodology was then assessed in two regions with known histories of degradation where it was found to accurately capture both the timing and directionality of ecosystem change.

Photobiodegradation of chlorinated water pollutants by a combined TiO2-polyaniline-enzyme catalytic system

NASA Astrophysics Data System (ADS)

Campanella, Luigi; Crescentini, G.; Militerno, S.

1995-10-01

The removal of xenobiotic compounds, such as chlorophenols and pesticides, from municipal and industrial wastewaters is an important task because of the toxicity and the tendency to bioaccumulation of these compounds. Among the several methods proposed, photodegradation catalyzed by suspended inorganic semiconductors (i.e. TiO2) has lately received wide attention because this process is fast, leads to non-toxic final products and shows a high degradation efficiency. In this work, the results obtained in the photodegradation of monochlorophenols using a new catalyst, made of TiO2 and polyaniline both immobilized on a polyvinylchloride (PVC) membrane, in presence (and in absence) of an enzyme are presented. Different enzymes have been tested by adding 5, 10 or 15 U/mL to 50 mL of aqueous solution (1 multiplied by 10-4 mol/L) of o-chloro-phenol containing the catalytic membrane. The samples were irradiated using a QUV panel accelerated weathering tester, which simulates very well the solar radiation up to lambda equals 400 nm and HPLC was used to measure the variation of the compound's concentration with the time. While some enzymes (i.e., peroxidase) do not improve the photodegradation process since they do not survive under the irradiation conditions used, some of them show marked effect both in terms of rate degradation and time required to reach the total degradation of the compound examined. For example, the addition of Laccase reduces the 100% degradation time from 35 hrs to about 20 hrs. Attempts to immobilize the enzyme on the catalytic membrane (by adsorption) have been carried out and the performance of the catalyst with non-immobilized and immobilized enzyme has been studied.

A review on data-driven fault severity assessment in rolling bearings

NASA Astrophysics Data System (ADS)

Cerrada, Mariela; Sánchez, René-Vinicio; Li, Chuan; Pacheco, Fannia; Cabrera, Diego; Valente de Oliveira, José; Vásquez, Rafael E.

2018-01-01

Health condition monitoring of rotating machinery is a crucial task to guarantee reliability in industrial processes. In particular, bearings are mechanical components used in most rotating devices and they represent the main source of faults in such equipments; reason for which research activities on detecting and diagnosing their faults have increased. Fault detection aims at identifying whether the device is or not in a fault condition, and diagnosis is commonly oriented towards identifying the fault mode of the device, after detection. An important step after fault detection and diagnosis is the analysis of the magnitude or the degradation level of the fault, because this represents a support to the decision-making process in condition based-maintenance. However, no extensive works are devoted to analyse this problem, or some works tackle it from the fault diagnosis point of view. In a rough manner, fault severity is associated with the magnitude of the fault. In bearings, fault severity can be related to the physical size of fault or a general degradation of the component. Due to literature regarding the severity assessment of bearing damages is limited, this paper aims at discussing the recent methods and techniques used to achieve the fault severity evaluation in the main components of the rolling bearings, such as inner race, outer race, and ball. The review is mainly focused on data-driven approaches such as signal processing for extracting the proper fault signatures associated with the damage degradation, and learning approaches that are used to identify degradation patterns with regards to health conditions. Finally, new challenges are highlighted in order to develop new contributions in this field.

Properties and degradation of the gasket component of a proton exchange membrane fuel cell--a review.

PubMed

Basuli, Utpal; Jose, Jobin; Lee, Ran Hee; Yoo, Yong Hwan; Jeong, Kwang-Un; Ahn, Jou-Hyeon; Nah, Changwoon

2012-10-01

Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed.

Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator

NASA Astrophysics Data System (ADS)

Catala-Civera, Jose M.; Canos-Marin, Antoni J.; de los Reyes, E.

2000-07-01

Microwave control capabilities have been used to monitor the degradation of polyol, an alcohol composite material commonly used in the footwear industry for polymerization purposes. The liquid flows continuously inside a thin pipe and its desirable properties are altered with time associated to moisture absorption processes. Consequently, variations in the dielectric properties are involved, and they can be detected by permittivity measurements. In this paper, in order to obtain high sensitivity and resolution, a rectangular cavity resonator working at a fixed frequency was designed using as sample holder a rectangular pipe containing the liquid going through. Changes in the liquid modify the original response of the cavity with a non- degraded liquid and these differences have been used to determine the degree of degradation of the material. The final response of the microwave resonator was experimentally validated with measurements in a continuous line.

Degradation Mechanisms in Blue Phosphorescent Organic Light-Emitting Devices by Exciton-Polaron Interactions: Loss in Quantum Yield versus Loss in Charge Balance.

PubMed

Zhang, Yingjie; Aziz, Hany

2017-01-11

We study the relative importance of deterioration of material quantum yield and charge balance to the electroluminescence stability of PHOLEDs, with a special emphasis on blue devices. Investigations show that the quantum yields of both host and emitter in the emission layer degrade due to exciton-polaron interactions and that the deterioration in material quantum yield plays the primary role in device degradation under operation. On the other hand, the results show that the charge balance factor is also affected by exciton-polaron interactions but only plays a secondary role in determining device stability. Finally, we show that the degradation mechanisms in blue PHOLEDs are fundamentally the same as those in green PHOLEDs. The limited stability of the blue devices is a result of faster deterioration in the quantum yield of the emitter.

Regulated Proteolysis in Bacteria.

PubMed

Mahmoud, Samar A; Chien, Peter

2018-06-20

Regulated proteolysis is a vital process that affects all living things. Bacteria use energy-dependent AAA+ proteases to power degradation of misfolded and native regulatory proteins. Given that proteolysis is an irreversible event, specificity and selectivity in degrading substrates are key. Specificity is often augmented through the use of adaptors that modify the inherent specificity of the proteolytic machinery. Regulated protein degradation is intricately linked to quality control, cell-cycle progression, and physiological transitions. In this review, we highlight recent work that has shed light on our understanding of regulated proteolysis in bacteria. We discuss the role AAA+ proteases play during balanced growth as well as how these proteases are deployed during changes in growth. We present examples of how protease selectivity can be controlled in increasingly complex ways. Finally, we describe how coupling a core recognition determinant to one or more modifying agents is a general theme for regulated protein degradation.

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation.

PubMed

Garcia, A C A; Rodrigues, M A S; Xavier, J L N; Gazulla, V; Meneguzzi, A; Bernardes, A M

2015-05-01

The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution.

Enzymatic degradation of cell wall and related plant polysaccharides.

PubMed

Ward, O P; Moo-Young, M

1989-01-01

Polysaccharides such as starch, cellulose and other glucans, pectins, xylans, mannans, and fructans are present as major structural and storage materials in plants. These constituents may be degraded and modified by endogenous enzymes during plant growth and development. In plant pathogenesis by microorganisms, extracellular enzymes secreted by infected strains play a major role in plant tissue degradation and invasion of the host. Many of these polysaccharide-degrading enzymes are also produced by microorganisms widely used in industrial enzyme production. Most commerical enzyme preparations contain an array of secondary activities in addition to the one or two principal components which have standardized activities. In the processing of unpurified carbohydrate materials such as cereals, fruits, and tubers, these secondary enzyme activities offer major potential for improving process efficiency. Use of more defined combinations of industrial polysaccharases should allow final control of existing enzyme processes and should also lead to the development of novel enzymatic applications.

[Effects of copper on biodegradation mechanism of trichloroethylene by mixed microorganisms].

PubMed

Gao, Yanhui; Zhao, Tiantao; Xing, Zhilin; He, Zhi; Zhang, Lijie; Peng, Xuya

2016-05-25

We isolated and enriched mixed microorganisms SWA1 from landfill cover soils supplemented with trichloroethylene (TCE). The microbial mixture could degrade TCE effectively under aerobic conditions. Then, we investigated the effect of copper ion (0 to 15 μmol/L) on TCE biodegradation. Results show that the maximum TCE degradation speed was 29.60 nmol/min with 95.75% degradation when copper ion was at 0.03 μmol/L. In addition, genes encoding key enzymes during biodegradation were analyzed by Real-time quantitative reverse transcription PCR (RT-qPCR). The relative expression abundance of pmoA gene (4.22E-03) and mmoX gene (9.30E-06) was the highest when copper ion was at 0.03 μmol/L. Finally, we also used MiSeq pyrosequencing to investigate the diversity of microbial community. Methylocystaceae that can co-metabolic degrade TCE were the dominant microorganisms; other microorganisms with the function of direct oxidation of TCE were also included in SWA1 and the microbial diversity decreased significantly along with increasing of copper ion concentration. Based on the above results, variation of copper ion concentration affected the composition of SWA1 and degradation mechanism of TCE. The degradation mechanism of TCE included co-metabolism degradation of methanotrophs and oxidation metabolism directly at copper ion of 0.03 μmol/L. When copper ion at 5 μmol/L (biodegradation was 84.75%), the degradation mechanism of TCE included direct-degradation and co-metabolism degradation of methanotrophs and microorganisms containing phenol hydroxylase. Therefore, biodegradation of TCE by microorganisms was a complicated process, the degradation mechanism included co-metabolism degradation of methanotrophs and bio-oxidation of non-methanotrophs.

Method of degrading pollutants in soil

DOEpatents

Hazen, T.C.; Lopez-De-Victoria, G.

1994-07-05

Disclosed are a method and system for enhancing the motility of microorganisms. This is accomplished by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant. 5 figures.

Preparation of Diatomite Supported Nano Zinc Oxide Composite Photocatalytic Material and Study on its Formaldehyde Degradation

NASA Astrophysics Data System (ADS)

Xiao, Liguang; Pang, Bo

2017-09-01

This experiment used zinc nitrate as precursor, ethanol as solvent and polyethylene glycol as dispersant, diatomite as carrier, diatomite loaded nano Zinc Oxide was prepared by sol-gel method, in addition, the formaldehyde degradation was studied by two kinds of experimental methods: preparation and loading, preparation and post loading, The samples were characterized by SEM, XRD, BET and IR. Experimental results showed that: Diatomite based nano Zinc Oxide had a continuous adsorption and degradation of formaldehyde, formaldehyde gas with initial concentration was 0.7mg/m3, after 36h degradation, the concentration reached 0.238mg/m3, the degradation rate reached to 66%.

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.

Modelisation spatio-temporelle de la vulnerabilite du milieu a la degradation des sols en milieu semi-aride a partir de donnees radar

NASA Astrophysics Data System (ADS)

Sylla, Daouda

Defined as a process that reduces the potential of soil production or the usefulness of natural resources, soil degradation is a major environmental problem which affects over 41 % of the land and, over 80 % of people affected by this phenomenon live in developing countries. The general objective of the present project is the characterisation of different types of land use and land cover and the detection of their spatio-temporal changes from radar data (ERS-1, RADARSAT-1 and ENVISAT) for a spatio-temporal modeling of environmental vulnerability to soil degradation in semi-arid area. Due to the high sensitivity of the radar signal to the observing conditions of the sensor and the target, a partition of the radar images with respect to their angular configurations (23° and [33°-35°-47°]) and to environmental conditions (wet and dry) was first performed. A good characterisation and a good temporal evolution of the four types of land use and land cover of interest are obtained with different levels of contrast depending on the incidence angles and environmental conditions. In addition to pixel-based approach used for change detection (images differences, Principal component analysis), a monitoring of land cover from an object-oriented approach which focused on two types of land cover is developed. The method allows a detailed mapping of bare soil occurrences as a function of environmental conditions. Finally, using different sources of information, a modeling of the environmental vulnerability to soil degradation is performed in the South-west of Niger from the probabilistic fusion rule of Dempster-Shafer. The resulting decision maps are statistically acceptable at 93 % and 91 % with Kappa values of 86 % and 84 %, for respectively dry and wet conditions. Besides, they are used to produce a global map of the environmental vulnerability to soil degradation in this semi-arid area. Key-words: Environmental vulnerability to soil degradation; data fusion; radar images; land use changes; semi-arid environment; South-west of Niger.

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.

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.

The use of ozone, ozone plus UV radiation, and aerobic microorganisms in the purification of some agro-industrial wastewaters.

PubMed

Benitez, F Javier; Acero, Juan L; Gonzalez, Teresa; Garcia, Juan

2002-08-01

The oxidation of the pollutant organic matter present in wastewaters generated during different stages in the black table-olive industry was investigated by using ozone alone or combined with UV radiation; by using aerobic microorganisms; and finally, by aerobic degradation of the previously ozonated wastewaters. In the ozonation processes, the removal of substrate (COD) and aromatic compounds, the decreases in BOD5 and pH, and the ozone consumed in the reaction were evaluated. A kinetic study was conducted that led to the evaluation of the stoichiometric ratio for the chemical reaction, as well as the rate constants for the substrate reduction and ozone disappearance. In the single aerobic degradation treatment, the evolution of substrate and biomass was monitored during the process, and a kinetic study was performed by applying the Contois model to the experimental data, giving the specific biokinetic constant, the cell yield coefficient, and the rate constant for the microorganism death phase. Finally, a combined process was performed, consisting in the aerobic degradation of pre-ozonated wastewaters, and the effect of such chemical pretreatment on the substrate removal and kinetic parameters of the later biological stage is discussed.

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.

α-Amino acid containing degradable polymers as functional biomaterials: rational design, synthetic pathway, and biomedical applications.

PubMed

Sun, Huanli; Meng, Fenghua; Dias, Aylvin A; Hendriks, Marc; Feijen, Jan; Zhong, Zhiyuan

2011-06-13

Currently, biomedical engineering is rapidly expanding, especially in the areas of drug delivery, gene transfer, tissue engineering, and regenerative medicine. A prerequisite for further development is the design and synthesis of novel multifunctional biomaterials that are biocompatible and biologically active, are biodegradable with a controlled degradation rate, and have tunable mechanical properties. In the past decades, different types of α-amino acid-containing degradable polymers have been actively developed with the aim to obtain biomimicking functional biomaterials. The use of α-amino acids as building units for degradable polymers may offer several advantages: (i) imparting chemical functionality, such as hydroxyl, amine, carboxyl, and thiol groups, which not only results in improved hydrophilicity and possible interactions with proteins and genes, but also facilitates further modification with bioactive molecules (e.g., drugs or biological cues); (ii) possibly improving materials biological properties, including cell-materials interactions (e.g., cell adhesion, migration) and degradability; (iii) enhancing thermal and mechanical properties; and (iv) providing metabolizable building units/blocks. In this paper, recent developments in the field of α-amino acid-containing degradable polymers are reviewed. First, synthetic approaches to prepare α-amino acid-containing degradable polymers will be discussed. Subsequently, the biomedical applications of these polymers in areas such as drug delivery, gene delivery and tissue engineering will be reviewed. Finally, the future perspectives of α-amino acid-containing degradable polymers will be evaluated.

PHB-degrading bacteria isolated from the gastrointestinal tract of aquatic animals as protective actors against luminescent vibriosis.

PubMed

Liu, Yiying; De Schryver, Peter; Van Delsen, Bart; Maignien, Loïs; Boon, Nico; Sorgeloos, Patrick; Verstraete, Willy; Bossier, Peter; Defoirdt, Tom

2010-10-01

The use of poly-β-hydroxybutyrate (PHB) was shown to be successful in increasing the resistance of brine shrimp against pathogenic infections. In this study, we isolated for the first time PHB-degrading bacteria from a gastrointestinal environment. Pure strains of PHB-degrading bacteria were isolated from Siberian sturgeon, European sea bass and giant river prawn. The capability of selected isolates to degrade PHB was confirmed in at least two of three setups: (1) growth in minimal medium containing PHB as the sole carbon (C) source, (2) production of clearing zones on minimal agar containing PHB as the sole C source and (3) degradation of PHB (as determined by HPLC analysis) in 10% Luria-Bertani medium containing PHB. Challenge tests showed that the PHB-degrading activity of the selected isolates increased the survival of brine shrimp larvae challenged to a pathogenic Vibrio campbellii strain by a factor 2-3. Finally, one of the PHB-degrading isolates from sturgeon showed a double biocontrol effect because it was also able to inactivate acylhomoserine lactones, a type of quorum-sensing molecule that regulates the virulence of different pathogenic bacteria. Thus, the combined supplementation of a PHB-degrading bacterium and PHB as a synbioticum provides perspectives for improving the gastrointestinal health of aquatic animals. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Chlorpyrifos degradation in a biomixture of biobed at different maturity stages.

PubMed

Tortella, G R; Rubilar, O; Castillo, M d P; Cea, M; Mella-Herrera, R; Diez, M C

2012-06-01

The biomixture is a principal element controlling the degradation efficacy of the biobed. The maturity of the biomixture used in the biobed affects its overall performance of the biobed, but this is not well studied yet. The aim of this research was to evaluate the effect of using a typical composition of Swedish biomixture at different maturity stages on the degradation of chlorpyrifos. Tests were made using biomixture at three maturity stages: 0 d (BC0), 15 d (BC15) and 30 d (BC30); chlorpyrifos was added to the biobeds at final concentration of 200, 320 and 480 mg kg(-1). Chlorpyrifos degradation in the biomixture was monitored over time. Formation of TCP (3,5,6-trichloro-2-pyrinidol) was also quantified, and hydrolytic and phenoloxidase activities measured. The biomixture efficiently degraded chlorpyrifos (degradation efficiency >50%) in all the evaluated maturity stages. However, chlorpyrifos degradation decreased with increasing concentrations of the pesticide. TCP formation occurred in all biomixtures, but a major accumulation was observed in BC30. Significant differences were found in both phenoloxidase and hydrolytic activities in the three maturity stages of biomixture evaluated. Also, these two biological activities were affected by the increase in pesticide concentration. In conclusion, our results demonstrated that chlorpyrifos can be degraded efficiently in all the evaluated maturity stages. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stress degradation studies and development of stability-indicating TLC-densitometry method for determination of prednisolone acetate and chloramphenicol in their individual and combined pharmaceutical formulations

PubMed Central

2012-01-01

A rapid and reproducible stability indicating TLC method was developed for the determination of prednisolone acetate and chloramphenicol in presence of their degraded products. Uniform degradation conditions were maintained by refluxing sixteen reaction mixtures for two hours at 80°C using parallel synthesizer including acidic, alkaline and neutral hydrolysis, oxidation and wet heating degradation. Oxidation at room temperature, photochemical and dry heating degradation studies were also carried out. Separation was done on TLC glass plates, pre-coated with silica gel 60F-254 using chloroform: methanol (14:1 v/v). Spots at Rf 0.21 ± 0.02 and Rf 0.41 ± 0.03 were recognized as chloramphenicol and prednisolone acetate, respectively. Quantitative analysis was done through densitometric measurements at multiwavelength (243 nm, λmax of prednisolone acetate and 278 nm, λmax of chloramphenicol), simultaneously. The developed method was optimized and validated as per ICH guidelines. Method was found linear over the concentration range of 200-6000 ng/spot with the correlation coefficient (r2 ± S.D.) of 0.9976 ± 3.5 and 0.9920 ± 2.5 for prednisolone acetate and chloramphenicol, respectively. The developed TLC method can be applied for routine analysis of prednisolone acetate and chloramphenicol in presence of their degraded products in their individual and combined pharmaceutical formulations. PMID:22264235

Bearing performance degradation assessment based on time-frequency code features and SOM network

NASA Astrophysics Data System (ADS)

Zhang, Yan; Tang, Baoping; Han, Yan; Deng, Lei

2017-04-01

Bearing performance degradation assessment and prognostics are extremely important in supporting maintenance decision and guaranteeing the system’s reliability. To achieve this goal, this paper proposes a novel feature extraction method for the degradation assessment and prognostics of bearings. Features of time-frequency codes (TFCs) are extracted from the time-frequency distribution using a hybrid procedure based on short-time Fourier transform (STFT) and non-negative matrix factorization (NMF) theory. An alternative way to design the health indicator is investigated by quantifying the similarity between feature vectors using a self-organizing map (SOM) network. On the basis of this idea, a new health indicator called time-frequency code quantification error (TFCQE) is proposed to assess the performance degradation of the bearing. This indicator is constructed based on the bearing real-time behavior and the SOM model that is previously trained with only the TFC vectors under the normal condition. Vibration signals collected from the bearing run-to-failure tests are used to validate the developed method. The comparison results demonstrate the superiority of the proposed TFCQE indicator over many other traditional features in terms of feature quality metrics, incipient degradation identification and achieving accurate prediction. Highlights • Time-frequency codes are extracted to reflect the signals’ characteristics. • SOM network served as a tool to quantify the similarity between feature vectors. • A new health indicator is proposed to demonstrate the whole stage of degradation development. • The method is useful for extracting the degradation features and detecting the incipient degradation. • The superiority of the proposed method is verified using experimental data.

Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species

NASA Astrophysics Data System (ADS)

Krysztofiak, G.; Catoire, V.; Poulet, G.; Marécal, V.; Pirre, M.; Louis, F.; Canneaux, S.; Josse, B.

2012-11-01

Detailed chemical reaction schemes for the atmospheric degradations of the very short-lived species (VSLS) bromoform (CHBr3) and dibromomethane (CH2Br2) have been established. These degradation schemes have been implemented in the meteorological/tracer transport model CATT-BRAMS used in the present case as pseudo one-dimensional model with chemistry of CH4, CO, HOx, NOx, NOy and Ox. They include the main possible reactions of the intermediate brominated peroxy radicals RO2 (with R = CH2Br, CHBr2 and CBr3) for which the most likely reaction pathways with HO2 have been found using ab initio computational calculations. The full degradation schemes have been run for two well-defined realistic scenarios, “clean” atmosphere and “moderately” NOy-polluted atmosphere, as representative of a tropical coastal region where these VSLS natural emissions are expected to be important. The Henry's law constants of the brominated organics products have been estimated by using the Bond Contribution Method (BCM; Meylan and Howard, 1991) or the Molecular Connectivity Index (MCI; Nirmalakhandan and Speece, 1988). Using these constants, the least soluble species formed from the VSLS degradation are found to be CBr2O, CHBrO, CBr3O2NO2, CHBr2O2NO2, BrO, BrONO2 and HOBr, which leads those to be potentially transported into the tropical tropopause layer (TTL) in case of deep convection and contribute to stratospheric bromine additionally to the original substances. For bromoform and dibromomethane degradation, the moderate NOy pollution increases the production of the least soluble species and thus approximately doubles the bromine quantity potentially able to reach the TTL (from 22.5% to 43% for CHBr3 and from 8.8% to 20.2% for CH2Br2). The influence of the reactions of the RO2 radicals with HO2, CH3O2 and NO2 on the nature and abundance of the stable intermediate and end-products has been tested for CHBr3 degradation. As a result, the reactions of the RO2 radicals with NO2 have no impact. Taking into account the reaction between RO2 and CH3O2 and modifying the branching ratios of the reaction between RO2 and HO2 lead to a small impact on the bromoform degradation by slightly decreasing (by 10%) the bromine quantity potentially able to reach the TTL. As a final point, in contrast to CHBr3, CH2Br2 degradation produces negligible quantities of organics species and the effects of pollution increase only the inorganic species production. By taking into account the results of these tests, new simplified degradation schemes for CHBr3 and CH2Br2 are proposed.

Surface Properties and Photocatalytic Activities of the Colloidal ZnS:Mn Nanocrystals Prepared at Various pH Conditions

PubMed Central

Heo, Jungho; Hwang, Cheong-Soo

2015-01-01

Water-dispersible ZnS:Mn nanocrystals (NC) were synthesized by capping the surface with mercaptoacetic acid (MAA) molecules at three different pH conditions. The obtained ZnS:Mn-MAA NC products were physically and optically characterized by corresponding spectroscopic methods. The UV-Visible absorption spectra and PL emission spectra showed broad peaks at 310 and 590 nm, respectively. The average particle sizes measured from the HR-TEM images were 5 nm, which were also supported by the Debye-Scherrer calculations using the X-ray diffraction (XRD) data. Moreover, the surface charges and the degrees of aggregation of the ZnS:Mn-MAA NCs were determined by electrophoretic and hydrodynamic light scattering methods, indicating formation of agglomerates in water with various sizes (50–440 nm) and different surface charge values accordingly the preparation conditions of the NCs (−7.59 to −24.98 mV). Finally, the relative photocatalytic activities of the ZnS:Mn-MAA NCs were evaluated by measuring the degradation rate of methylene blue (MB) molecule in a pseudo first-order reaction condition under the UV-visible light irradiation. As a result, the ZnS:Mn-MAA NC prepared at the pH 7 showed the best photo-degradation efficiency of the MB molecule with the first-order rate constant (kobs) of 2.0 × 10−3·min−1. PMID:28347105

A high-throughput assay for enzymatic polyester hydrolysis activity by fluorimetric detection.

PubMed

Wei, Ren; Oeser, Thorsten; Billig, Susan; Zimmermann, Wolfgang

2012-12-01

A fluorimetric assay for the fast determination of the activity of polyester-hydrolyzing enzymes in a large number of samples has been developed. Terephthalic acid (TPA) is a main product of the enzymatic hydrolysis of polyethylene terephthalate (PET), a synthetic polyester. Terephthalate has been quantified following its conversion to the fluorescent 2-hydroxyterephthalate by an iron autoxidation-mediated generation of free hydroxyl radicals. The assay proved to be robust at different buffer concentrations, reaction times, pH values, and in the presence of proteins. A validation of the assay was performed by analyzing TPA formation from PET films and nanoparticles catalyzed by a polyester hydrolase from Thermobifida fusca KW3 in a 96-well microplate format. The results showed a close correlation (R(2) = 0.99) with those obtained by a considerably more tedious and time-consuming HPLC method, suggesting the aptness of the fluorimetric assay for a high-throughput screening for polyester hydrolases. The method described in this paper will facilitate the detection and development of biocatalysts for the modification and degradation of synthetic polymers. The fluorimetric assay can be used to quantify the amount of TPA obtained as the final degradation product of the enzymatic hydrolysis of PET. In a microplate format, this assay can be applied for the high-throughput screening of polyester hydrolases. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Subsidence in tropical peatlands: Estimating CO2 fluxes from peatlands in Southeast Asia

NASA Astrophysics Data System (ADS)

Hoyt, A.; Harvey, C. F.; Seppalainen, S. S.; Chaussard, E.

2017-12-01

Tropical peatlands of Southeast Asia are an important global carbon stock. However, they are being rapidly deforested and drained. Peatland drainage facilitates peat decomposition, releases sequestered peat carbon to the atmosphere as CO2, and leads to subsidence of the peat surface. As a result, subsidence measurements can be used to monitor peatland carbon loss over time. Until now, subsidence measurements have been primarily limited to ground-based point measurements using subsidence poles. Here we demonstrate a powerful method to measure peatland subsidence rates across much larger areas than ever before. Using remotely sensed InSAR data, we map subsidence rates across thousands of square kilometers in Southeast Asia and validate our results against ground-based subsidence measurements. The method allows us to monitor subsidence in remote locations, providing unprecedented spatial information, and the first comprehensive survey of land uses such as degraded peatlands, burnt and open areas, shrub lands, and smallholder farmlands. Strong spatial patterns emerged, with the highest subsidence rates occurring at the centers of peat domes, where the peat is thickest and drainage depths are likely to be largest. Peatland subsidence rates were also strongly dependent on current and historical land use, with typical subsidence rates ranging from 2-4 cm/yr. Finally, we scaled up our results to calculate total annual emissions from peat decomposition in degraded peatlands.

Effects of earthworm casts and zeolite on the two-stage composting of green waste

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

Zhang, Lu, E-mail: zhanglu1211@gmail.com; Sun, Xiangyang, E-mail: xysunbjfu@gmail.com

2015-05-15

Highlights: • Earthworm casts (EWCs) and clinoptilolite (CL) were used in green waste composting. • Addition of EWCs + CL improved physico-chemical and microbiological properties. • Addition of EWCs + CL extended the duration of thermophilic periods during composting. • Addition of EWCs + CL enhanced humification, cellulose degradation, and nutrients. • Combined addition of 0.30% EWCs + 25% CL reduced composting time to 21 days. - Abstract: Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthwormmore » casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21 days with the optimized two-stage composting method rather than in the 90–270 days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL.« less

Apoptosis after gamma irradiation. Is it an important cell death modality?

PubMed Central

Siles, E.; Villalobos, M.; Jones, L.; Guerrero, R.; Eady, J. J.; Valenzuela, M. T.; Núñez, M. I.; McMillan, T. J.; Ruiz de Almodóvar, J. M.

1998-01-01

Apoptosis and necrosis are two different forms of cell death that can be induced by cytotoxic stress, such as ionizing radiation. We have studied the importance of apoptotic death induced after treatment with 6 Gy of gamma-irradiation in a panel of eight human tumour cell lines of different radiosensitivities. Three different techniques based on the detection of DNA fragmentation have been used, a qualitative one--DNA ladder formation --and two quantitative approaches--in situ tailing and comet assay. No statistically significant relationship between the two quantitative assays was found (r= 0.327, P = 0.159) so these methods seem to show different aspects of the process of cell death. The presence of the DNA ladder related well to the end-labelling method in that the least amount of end labelling was seen in samples in which necrotic degradation rather than apoptotic ladders were seen. However, as the results obtained by the comet assay are not in agreement with the DNA ladder experiments, we suggest that the distinction between the degraded DNA produced by apoptosis and necrosis may be difficult by this technique. Finally, although apoptosis has been proposed to be dependent on p53 functionality, and this may explain differences in cellular radiosensitivity, no statistically significant relationship was found between these parameters and apoptosis in the eight cell lines studied. PMID:9862569

Enhanced magneto-optical and photo-catalytic properties of transition metal cobalt (Co2+ ions) doped spinel MgFe2O4 ferrite nanocomposites

NASA Astrophysics Data System (ADS)

Abraham, A. Godlyn; Manikandan, A.; Manikandan, E.; Vadivel, S.; Jaganathan, S. K.; Baykal, A.; Renganathan, P. Sri

2018-04-01

In this study, spinel magnesium cobalt ferrite (CoxMg1-xFe2O4: x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanocomposites were synthesized successfully by modified sol-gel combustion method. Magnesium nitrate, cobalt nitrate and iron nitrate were used as the source of divalent (Mg2+ and Co2+) and trivalent (Fe3+) cations, respectively and urea were used as the reducing (fuel) agent. The effects of cobalt ions on morphology, structural, optical, magnetic and photo-catalytic properties of spinel CoxMg1-xFe2O4 nanocomposites were investigated. Various characterization methods, including X-ray powder diffraction (XRD), high resolution scanning electron microscope (HR-SEM), transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM) and photo-catalytic degradation (PCD) activity were used to study the phase purity, microstructure, particle size, elemental composition, functional group determination, band gap calculation, magnetic properties and degradation efficiency of nanoparticles, respectively. The observed results showed that the final products consists cubic spinel phase with sphere-like nanoparticles morphologies. Furthermore, spinel Co0.6Mg0.4Fe2O4 nanocomposite showed highest PCD efficiency (98.55%) than other composition of ferrite nanoparticles.

Promotion by humus-reducing bacteria for the degradation of UV254 absorbance in reverse-osmosis concentrates pretreated with O3-assisted UV-Fenton method.

PubMed

Xia, Jiaohui; Zhang, Hui; Ding, Shaoxuan; Li, Changyu; Ding, Jincheng; Lu, Jie

2017-07-12

The primary pollutants in reverse-osmosis concentrates (ROC) are the substances with the UV absorbance at 254 nm (UV 254 ), which is closely related to humic substances that can be degraded by humus-reducing bacteria. This work studied the degradation characteristics of humus-reducing bacteria in ROC treatment. The physiological and biochemical characteristics of humus-reducing bacteria were investigated, and the effects of pH values and electron donors on the reduction of humic analog, antraquinone-2, 6-disulfonate were explored to optimize the degradation. Furthermore, the O 3 -assisted UV-Fenton method was applied for the pretreatment of ROC, and the degradation of UV 254 absorbance was apparently promoted with their removal rate, reaching 84.2% after 10 days of degradation by humus-reducing bacteria.

Differentiating climate- and human-induced drivers of grassland degradation in the Liao River Basin, China.

PubMed

He, Chunyang; Tian, Jie; Gao, Bin; Zhao, Yuanyuan

2015-01-01

Quantitatively distinguishing grassland degradation due to climatic variations from that due to human activities is of great significance to effectively governing degraded grassland and realizing sustainable utilization. The objective of this study was to differentiate these two types of drivers in the Liao River Basin during 1999-2009 using the residual trend (RESTREND) method and to evaluate the applicability of the method in semiarid and semihumid regions. The relationship between the normalized difference vegetation index (NDVI) and each climatic factor was first determined. Then, the primary driver of grassland degradation was identified by calculating the change trend of the normalized residuals between the observed and the predicted NDVI assuming that climate change was the only driver. We found that the RESTREND method can be used to quantitatively and effectively differentiate climate and human drivers of grassland degradation. We also found that the grassland degradation in the Liao River Basin was driven by both natural processes and human activities. The driving factors of grassland degradation varied greatly across the study area, which included regions having different precipitation and altitude. The degradation in the Horqin Sandy Land, with lower altitude, was driven mainly by human activities, whereas that in the Kungl Prairie, with higher altitude and lower precipitation, was caused primarily by climate change. Therefore, the drivers of degradation and local conditions should be considered in an appropriate strategy for grassland management to promote the sustainability of grasslands in the Liao River Basin.

Implementation and Validation of an Impedance Eduction Technique

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Jones, Michael G.; Gerhold, Carl H.

2011-01-01

Implementation of a pressure gradient method of impedance eduction in two NASA Langley flow ducts is described. The Grazing Flow Impedance Tube only supports plane-wave sources, while the Curved Duct Test Rig supports sources that contain higher-order modes. Multiple exercises are used to validate this new impedance eduction method. First, synthesized data for a hard wall insert and a conventional liner mounted in the Grazing Flow Impedance Tube are used as input to the two impedance eduction methods, the pressure gradient method and a previously validated wall pressure method. Comparisons between the two results are excellent. Next, data measured in the Grazing Flow Impedance Tube are used as input to both methods. Results from the two methods compare quite favorably for sufficiently low Mach numbers but this comparison degrades at Mach 0.5, especially when the hard wall insert is used. Finally, data measured with a hard wall insert mounted in the Curved Duct Test Rig are used as input to the pressure gradient method. Significant deviation from the known solution is observed, which is believed to be largely due to 3-D effects in this flow duct. Potential solutions to this issue are currently being explored.

Restoration of motion blurred images

NASA Astrophysics Data System (ADS)

Gaxiola, Leopoldo N.; Juarez-Salazar, Rigoberto; Diaz-Ramirez, Victor H.

2017-08-01

Image restoration is a classic problem in image processing. Image degradations can occur due to several reasons, for instance, imperfections of imaging systems, quantization errors, atmospheric turbulence, relative motion between camera or objects, among others. Motion blur is a typical degradation in dynamic imaging systems. In this work, we present a method to estimate the parameters of linear motion blur degradation from a captured blurred image. The proposed method is based on analyzing the frequency spectrum of a captured image in order to firstly estimate the degradation parameters, and then, to restore the image with a linear filter. The performance of the proposed method is evaluated by processing synthetic and real-life images. The obtained results are characterized in terms of accuracy of image restoration given by an objective criterion.

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.

Mechanisms of Bond Cleavage during Manganese Oxide and UV Degradation of Glyphosate: Results from Phosphate Oxygen Isotopes and Molecular Simulations.

PubMed

Jaisi, Deb P; Li, Hui; Wallace, Adam F; Paudel, Prajwal; Sun, Mingjing; Balakrishna, Avula; Lerch, Robert N

2016-11-16

Degradation of glyphosate in the presence of manganese oxide and UV light was analyzed using phosphate oxygen isotope ratios and density function theory (DFT). The preference of C-P or C-N bond cleavage was found to vary with changing glyphosate/manganese oxide ratios, indicating the potential role of sorption-induced conformational changes on the composition of intermediate degradation products. Isotope data confirmed that one oxygen atom derived solely from water was incorporated into the released phosphate during glyphosate degradation, and this might suggest similar nucleophilic substitution at P centers and C-P bond cleavage both in manganese oxide- and UV light-mediated degradation. The DFT results reveal that the C-P bond could be cleaved by water, OH - or • OH, with the energy barrier opposing bond dissociation being lowest in the presence of the radical species, and that C-N bond cleavage is favored by the formation of both nitrogen- and carbon-centered radicals. Overall, these results highlight the factors controlling the dominance of C-P or C-N bond cleavage that determines the composition of intermediate/final products and ultimately the degradation pathway.

The effect of mechanical loads on the degradation of aliphatic biodegradable polyesters.

PubMed

Li, Ying; Chu, Zhaowei; Li, Xiaoming; Ding, Xili; Guo, Meng; Zhao, Haoran; Yao, Jie; Wang, Lizhen; Cai, Qiang; Fan, Yubo

2017-06-01

Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices. The performances during biodegradation process play crucial roles for final realization of their functions. Because physiological and biochemical environment in vivo significantly affects biodegradation process, large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades. In this review article, we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process. Other physiological and biochemical factors related to mechanical loads were also discussed. The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer. Besides, the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers. This indicated that investigations into effects of mechanical loads on the degradation should be indispensable. More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately. Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.

[Studies on photo-electron-chemical catalytic degradation of the malachite green].

PubMed

Li, Ming-yu; Diao, Zeng-hui; Song, Lin; Wang, Xin-le; Zhang, Yuan-ming

2010-07-01

A novel two-compartment photo-electro-chemical catalytic reactor was designed. The TiO2/Ti thin film electrode thermally formed was used as photo-anode, and graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The anode compartment and cathode compartment were connected with the ionic exchange membrane in this reactor. Effects of initial pH, initial concentration of malachite green and connective modes between the anode compartment and cathode compartment on the decolorization efficiency of malachite green were investigated. The degradation dynamics of malachite green was studied. Based on the change of UV-visible light spectrum, the degradation process of malachite green was discussed. The experimental results showed that, during the time of 120 min, the decolouring ratio of the malachite green was 97.7% when initial concentration of malachite green is 30 mg x L(-1) and initial pH is 3.0. The catalytic degradation of malachite green was a pseudo-first order reaction. In the degradation process of malachite green the azo bond cleavage and the conjugated system of malachite green were attacked by hydroxyl radical. Simultaneity, the aromatic ring was oxidized. Finally, malachite green was degraded into other small molecular compounds.

Sensitivity and specificity of univariate MRI analysis of experimentally degraded cartilage

PubMed Central

Lin, Ping-Chang; Reiter, David A.; Spencer, Richard G.

2010-01-01

MRI is increasingly used to evaluate cartilage in tissue constructs, explants, and animal and patient studies. However, while mean values of MR parameters, including T1, T2, magnetization transfer rate km, apparent diffusion coefficient ADC, and the dGEMRIC-derived fixed charge density, correlate with tissue status, the ability to classify tissue according to these parameters has not been explored. Therefore, the sensitivity and specificity with which each of these parameters was able to distinguish between normal and trypsin- degraded, and between normal and collagenase-degraded, cartilage explants were determined. Initial analysis was performed using a training set to determine simple group means to which parameters obtained from a validation set were compared. T1 and ADC showed the greatest ability to discriminate between normal and degraded cartilage. Further analysis with k-means clustering, which eliminates the need for a priori identification of sample status, generally performed comparably. Use of fuzzy c-means (FCM) clustering to define centroids likewise did not result in improvement in discrimination. Finally, a FCM clustering approach in which validation samples were assigned in a probabilistic fashion to control and degraded groups was implemented, reflecting the range of tissue characteristics seen with cartilage degradation. PMID:19705467

Iron-Binding Protein Degradation by Cysteine Proteases of Naegleria fowleri.

PubMed

Martínez-Castillo, Moisés; Ramírez-Rico, Gerardo; Serrano-Luna, Jesús; Shibayama, Mineko

2015-01-01

Naegleria fowleri causes acute and fulminant primary amoebic meningoencephalitis. This microorganism invades its host by penetrating the olfactory mucosa and then traveling up the mesaxonal spaces and crossing the cribriform plate; finally, the trophozoites invade the olfactory bulbs. During its invasion, the protozoan obtains nutrients such as proteins, lipids, carbohydrates, and cationic ions (e.g., iron, calcium, and sodium) from the host. However, the mechanism by which these ions are obtained, particularly iron, is poorly understood. In the present study, we evaluated the ability of N. fowleri to degrade iron-binding proteins, including hololactoferrin, transferrin, ferritin, and hemoglobin. Zymography assays were performed for each substrate under physiological conditions (pH 7 at 37°C) employing conditioned medium (CM) and total crude extracts (TCEs) of N. fowleri. Different degradation patterns with CM were observed for hololactoferrin, transferrin, and hemoglobin; however, CM did not cause ferritin degradation. In contrast, the TCEs degraded only hololactoferrin and transferrin. Inhibition assays revealed that cysteine proteases were involved in this process. Based on these results, we suggest that CM and TCEs of N. fowleri degrade iron-binding proteins by employing cysteine proteases, which enables the parasite to obtain iron to survive while invading the central nervous system.

Iron-Binding Protein Degradation by Cysteine Proteases of Naegleria fowleri

PubMed Central

Ramírez-Rico, Gerardo; Serrano-Luna, Jesús; Shibayama, Mineko

2015-01-01

Naegleria fowleri causes acute and fulminant primary amoebic meningoencephalitis. This microorganism invades its host by penetrating the olfactory mucosa and then traveling up the mesaxonal spaces and crossing the cribriform plate; finally, the trophozoites invade the olfactory bulbs. During its invasion, the protozoan obtains nutrients such as proteins, lipids, carbohydrates, and cationic ions (e.g., iron, calcium, and sodium) from the host. However, the mechanism by which these ions are obtained, particularly iron, is poorly understood. In the present study, we evaluated the ability of N. fowleri to degrade iron-binding proteins, including hololactoferrin, transferrin, ferritin, and hemoglobin. Zymography assays were performed for each substrate under physiological conditions (pH 7 at 37°C) employing conditioned medium (CM) and total crude extracts (TCEs) of N. fowleri. Different degradation patterns with CM were observed for hololactoferrin, transferrin, and hemoglobin; however, CM did not cause ferritin degradation. In contrast, the TCEs degraded only hololactoferrin and transferrin. Inhibition assays revealed that cysteine proteases were involved in this process. Based on these results, we suggest that CM and TCEs of N. fowleri degrade iron-binding proteins by employing cysteine proteases, which enables the parasite to obtain iron to survive while invading the central nervous system. PMID:26090408

Fibrous scaffolds fabricated by emulsion electrospinning: from hosting capacity to in vivo biocompatibility

NASA Astrophysics Data System (ADS)

Spano, F.; Quarta, A.; Martelli, C.; Ottobrini, L.; Rossi, R. M.; Gigli, G.; Blasi, L.

2016-04-01

Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation.Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00782a

Improving degradation of emerging organic compounds by applying chaotic advection in Managed Aquifer Recharge in randomly heterogeneous porous media

NASA Astrophysics Data System (ADS)

Rodríguez-Escales, P.; Fernà ndez-Garcia, D.; Drechsel, J.; Folch, A.; Sanchez-Vila, X.

2017-05-01

Improving degradation rates of emerging organic compounds (EOCs) in groundwater is still a challenge. Although their degradation is not fully understood, it has been observed that some substances are preferably degraded under specific redox conditions. The coupling of Managed Aquifer Recharge with soil aquifer remediation treatment, by placing a reactive layer containing organic matter at the bottom of the infiltration pond, is a promising technology to improve the rate of degradation of EOCs. Its success is based on assuming that recharged water and groundwater get well mixed, which is not always true. It has been demonstrated that mixing can be enhanced by inducing chaotic advection through extraction-injection-engineering. In this work, we analyze how chaotic advection might enhance the spreading of redox conditions with the final aim of improving degradation of a mix of benzotriazoles: benzotriazole, 5-methyl-benzotriazole, and 5-chloro-benzotriazole. The degradation of the first two compounds was fastest under aerobic conditions whereas the third compound was best degraded under denitrification conditions. We developed a reactive transport model that describes how a recharged water rich in organic matter mixes with groundwater, how this organic matter is oxidized by different electron acceptors, and how the benzotriazoles are degraded attending for the redox state. The model was tested in different scenarios of recharge, both in homogenous and in heterogenous media. It was found that chaotic flow increases the spreading of the plume of recharged water. Consequently, different redox conditions coexist at a given time, facilitating the degradation of EOCs.

Solar activated ozonation of phenol and malic acid.

PubMed

Sánchez, Laura; Domènech, Xavier; Casado, Juan; Peral, José

2003-03-01

The effect that sunlight has on the degradation rate of two model organic compounds, phenol and malic acid, by ozone is studied. The effect seems to be due to both direct light absorption (300-320 nm photons) by ozone, which produces the pollutant degradation, and light absorption by reaction intermediates. The presence of such a light notably improves the reactivity of ozone toward the organic species, leading to a faster and complete mineralization even at large initial total organic carbon values. The use of artificial sunlight (Xe lamp) is also explored. Finally, the simultaneous presence of sunlight and other ozone degradation catalyst like transition metal ions is studied, showing the beneficial effect of such a combination. Copyright 2002 Elsevier Science Ltd.

In-liquid arc plasma jet and its application to phenol degradation

NASA Astrophysics Data System (ADS)

Liu, Jing-Lin; Park, Hyun-Woo; Hamdan, Ahmad; Cha, Min Suk

2018-03-01

We present a new method for achieving chemical reactions induced by plasmas with liquids—an in-liquid arc plasma jet system—designed to have a few advantages over the existing methods. High-speed imaging and optical emission spectroscopy were adopted to highlight the physical aspects of the in-liquid arc plasma jet system, and the feasibility of the system was investigated in a wastewater treatment case with phenol as the model contaminant. We found that the specific energy input is a reasonable parameter by which to characterize the overall process. The phenol removal reaction could be modeled as a pseudo-first-order reaction, and the reaction constant became smaller as the phenol concentration increased. However, complete decomposition of the phenol into water and carbon dioxide required very high energy because the final intermediate, oxalic acid, is relatively stable. Detailed chemical and physical analyses, including byproducts, ions, solution acidity, and conductivity, were conducted to evaluate this new method for use in the appropriate applications.

Numerical simulation study on rolling-chemical milling process of aluminum-lithium alloy skin panel

NASA Astrophysics Data System (ADS)

Huang, Z. B.; Sun, Z. G.; Sun, X. F.; Li, X. Q.

2017-09-01

Single curvature parts such as aircraft fuselage skin panels are usually manufactured by rolling-chemical milling process, which is usually faced with the problem of geometric accuracy caused by springback. In most cases, the methods of manual adjustment and multiple roll bending are used to control or eliminate the springback. However, these methods can cause the increase of product cost and cycle, and lead to material performance degradation. Therefore, it is of significance to precisely control the springback of rolling-chemical milling process. In this paper, using the method of experiment and numerical simulation on rolling-chemical milling process, the simulation model for rolling-chemical milling process of 2060-T8 aluminum-lithium alloy skin was established and testified by the comparison between numerical simulation and experiment results for the validity. Then, based on the numerical simulation model, the relative technological parameters which influence on the curvature of the skin panel were analyzed. Finally, the prediction of springback and the compensation can be realized by controlling the process parameters.

The Enhancement of 3D Scans Depth Resolution Obtained by Confocal Scanning of Porous Materials

NASA Astrophysics Data System (ADS)

Martisek, Dalibor; Prochazkova, Jana

2017-12-01

The 3D reconstruction of simple structured materials using a confocal microscope is widely used in many different areas including civil engineering. Nonetheless, scans of porous materials such as concrete or cement paste are highly problematic. The well-known problem of these scans is low depth resolution in comparison to the horizontal and vertical resolution. The degradation of the image depth resolution is caused by systematic errors and especially by different random events. Our method is focused on the elimination of such random events, mainly the additive noise. We use an averaging method based on the Lindeberg-Lévy theorem that improves the final depth resolution to a level comparable with horizontal and vertical resolution. Moreover, using the least square method, we also precisely determine the limit value of a depth resolution. Therefore, we can continuously evaluate the difference between current resolution and the optimal one. This substantially simplifies the scanning process because the operator can easily determine the required number of scans.

Reassignment of scattered emission photons in multifocal multiphoton microscopy.

PubMed

Cha, Jae Won; Singh, Vijay Raj; Kim, Ki Hean; Subramanian, Jaichandar; Peng, Qiwen; Yu, Hanry; Nedivi, Elly; So, Peter T C

2014-06-05

Multifocal multiphoton microscopy (MMM) achieves fast imaging by simultaneously scanning multiple foci across different regions of specimen. The use of imaging detectors in MMM, such as CCD or CMOS, results in degradation of image signal-to-noise-ratio (SNR) due to the scattering of emitted photons. SNR can be partly recovered using multianode photomultiplier tubes (MAPMT). In this design, however, emission photons scattered to neighbor anodes are encoded by the foci scan location resulting in ghost images. The crosstalk between different anodes is currently measured a priori, which is cumbersome as it depends specimen properties. Here, we present the photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, for quantification of crosstalk between the anodes of MAPMT without a priori measurement. The method provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image.

Sparse representation-based image restoration via nonlocal supervised coding

NASA Astrophysics Data System (ADS)

Li, Ao; Chen, Deyun; Sun, Guanglu; Lin, Kezheng

2016-10-01

Sparse representation (SR) and nonlocal technique (NLT) have shown great potential in low-level image processing. However, due to the degradation of the observed image, SR and NLT may not be accurate enough to obtain a faithful restoration results when they are used independently. To improve the performance, in this paper, a nonlocal supervised coding strategy-based NLT for image restoration is proposed. The novel method has three main contributions. First, to exploit the useful nonlocal patches, a nonnegative sparse representation is introduced, whose coefficients can be utilized as the supervised weights among patches. Second, a novel objective function is proposed, which integrated the supervised weights learning and the nonlocal sparse coding to guarantee a more promising solution. Finally, to make the minimization tractable and convergence, a numerical scheme based on iterative shrinkage thresholding is developed to solve the above underdetermined inverse problem. The extensive experiments validate the effectiveness of the proposed method.

Microalgae-mediated simultaneous treatment of toxic thiocyanate and production of biodiesel.

PubMed

Ryu, Byung-Gon; Kim, Jungmin; Yoo, Gursong; Lim, Jun-Taek; Kim, Woong; Han, Jong-In; Yang, Ji-Won

2014-04-01

In this work, a method for simultaneously degrading the toxic pollutant, thiocyanate, and producing microalgal lipids using mixed microbial communities was developed. Aerobic activated sludge was used as the seed culture and thiocyanate was used as the sole nitrogen source. Two cultivation methods were sequentially employed: a lithoautotrophic mode and a photoautotrophic mode. Thiocyanate hydrolysis and a nitrification was found to occur under the first (lithoautotrophic) condition, while the oxidized forms of nitrogen were assimilated by the photoautotrophic consortium and lipids were produced under the second condition. The final culture exhibited good settling efficiency (∼ 70% settling over 10 min), which can benefit downstream processing. The highest CO2 fixation rate and lipid productivity were observed with 2.5% and 5% CO2, respectively. The proposed integrated algal-bacterial system appears to be a feasible and even beneficial option for thiocyanate treatment and production of microbial lipids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bacterial Cell Wall Precursor Phosphatase Assays Using Thin-layer Chromatography (TLC) and High Pressure Liquid Chromatography (HPLC).

PubMed

Pazos, Manuel; Otten, Christian; Vollmer, Waldemar

2018-03-20

Peptidoglycan encases the bacterial cytoplasmic membrane to protect the cell from lysis due to the turgor. The final steps of peptidoglycan synthesis require a membrane-anchored substrate called lipid II, in which the peptidoglycan subunit is linked to the carrier lipid undecaprenol via a pyrophosphate moiety. Lipid II is the target of glycopeptide antibiotics and several antimicrobial peptides, and is degraded by 'attacking' enzymes involved in bacterial competition to induce lysis. Here we describe two protocols using thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC), respectively, to assay the digestion of lipid II by phosphatases such as Colicin M or the LXG toxin protein TelC from Streptococcus intermedius . The TLC method can also monitor the digestion of undecaprenyl (pyro)phosphate, whereas the HPLC method allows to separate the di-, mono- or unphosphorylated disaccharide pentapeptide products of lipid II.

Bacterial Cell Wall Precursor Phosphatase Assays Using Thin-layer Chromatography (TLC) and High Pressure Liquid Chromatography (HPLC)

PubMed Central

Pazos, Manuel; Otten, Christian; Vollmer, Waldemar

2018-01-01

Peptidoglycan encases the bacterial cytoplasmic membrane to protect the cell from lysis due to the turgor. The final steps of peptidoglycan synthesis require a membrane-anchored substrate called lipid II, in which the peptidoglycan subunit is linked to the carrier lipid undecaprenol via a pyrophosphate moiety. Lipid II is the target of glycopeptide antibiotics and several antimicrobial peptides, and is degraded by ‘attacking’ enzymes involved in bacterial competition to induce lysis. Here we describe two protocols using thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC), respectively, to assay the digestion of lipid II by phosphatases such as Colicin M or the LXG toxin protein TelC from Streptococcus intermedius. The TLC method can also monitor the digestion of undecaprenyl (pyro)phosphate, whereas the HPLC method allows to separate the di-, mono- or unphosphorylated disaccharide pentapeptide products of lipid II. PMID:29651453

The cell-in-series method: A technique for accelerated electrode degradation in redox flow batteries

DOE PAGES

Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.; ...

2015-11-21

Here, we demonstrate a novel method to accelerate electrode degradation in redox flow batteries and apply this method to the all-vanadium chemistry. Electrode performance degradation occurred seven times faster than in a typical cycling experiment, enabling rapid evaluation of materials. This method also enables the steady-state study of electrodes. In this manner, it is possible to delineate whether specific operating conditions induce performance degradation; we found that both aggressively charging and discharging result in performance loss. Post-mortem x-ray photoelectron spectroscopy of the degraded electrodes was used to resolve the effects of state of charge (SoC) and current on the electrodemore » surface chemistry. For the electrode material tested in this work, we found evidence that a loss of oxygen content on the negative electrode cannot explain decreased cell performance. Furthermore, the effects of decreased electrode and membrane performance on capacity fade in a typical cycling battery were decoupled from crossover; electrode and membrane performance decay were responsible for a 22% fade in capacity, while crossover caused a 12% fade.« less

Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

PubMed

De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

2010-08-01

During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.

Popular pharmaceutical residues in hospital wastewater: quantification and qualification of degradation products by mass spectroscopy after treatment with membrane bioreactor.

PubMed

Chiarello, M; Minetto, L; Giustina, S V Della; Beal, L L; Moura, S

2016-08-01

The occurrence of drugs in wastewater has been considered an imminent risk to the population, for the treatments used are usually ineffective. The presence of four popular drug residues (metformin, paracetamol, tetracycline, and enalapril) in hospital effluents, by using ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS) with electrospray (ESI) ionization, and removal/degradation by membrane bioreactor (MBR) system are investigated in this study. For analysis method, all standard calibration curves showed satisfactory linearity (R (2) ≥ 0.993) within a relatively wide range. The recovery was between 70.4 and 105.0 %, and the relative standard deviation (RSD) values were within the ranges of 8.2 and 13.5 %. The effluent samples were collected at the end of the process treated in a bench-scale MBR treatment system and preconcentrated on solid-phase extraction (SPE) cartridges. Following that procedure, the chemical analysis demonstrated that the MBR system was effective in enalapril 94.3 ± 7.63 %, tetracycline 99.4 ± 0.02 %, and paracetamol 98.8 ± 0.86 % removal. However, the polar metformin was less effectively removed (35.4 ± 12.49 %). Moreover, the degradation products were investigated using high-resolution mass spectrometry (HRMS) by quadrupole-time of flight (Q-TOF), which has been indicated a tetracycline metabolite. In order to investigate the environmental impact, the wastewater potential risk was evaluated. The risk quotient (RQ) by measure environmental concentration (MEC) and its predicted no effect concentration (PNEC) ratio (RQ = MEC/PNEC) was between 0.003 (enalapril) to 0.815 (paracetamol). Finally, this work demonstrates that UFLC-MS/MS (ESI-Q) is a sensitive and selective method for drug analysis in wastewater and with ESI-Q-TOF has the accuracy required for determining the degradation products of these compounds. Also, it indicated that membrane bioreactor systems represent a new generation of processes that have proved to outperform conventional treatment showing better effluent quality. The removal capacity studied in this work demonstrates the efficiency of this process.

Photocatalytic and Photoelectrochemically Degradation of Chlorsulfuron herbicide

NASA Astrophysics Data System (ADS)

Guo, Xu; Liu, Hongwei; Miao, Jinjie; Ma, Zhen

2017-12-01

Photocatalytic and photo electrochemical (PEC) degradation of chlorsulfuron herbicide were studied. Two novel PEC electrodes Ti/IrO2-Pt-WO3 (TIW) and Ti/IrO2-Pt-Ag3PO4 (TIA) were designed and some important factors were studied. Lower current density showed lower removal efficiency than higher conditions by electrochemical method. Furthermore, PEC showed higher degradation efficiency than the sum of individual EO and photocatalytic methode.

Alternate seal configuration for lithium primary cells

NASA Technical Reports Server (NTRS)

Kelley, J. A.

1982-01-01

The problem of glass degradation in the glass-to-metal seals in lithium/sulfur dioxide cells is discussed. The glass degradation mechanism is attributed to lithium reacting with glass which is a result of deposition of lithium at the glass/metal/electrolyte interface. The worst degradation was observed when cells were stored in the inverted position. Alternate sealing methods were examined and a modified Ziegler seal is considered to be one of the best possible methods. The seal consists of a crimp type soft seal using a plastic annulus and a metal tube. Results of degradation tests are presented.

Recommendations for the treatment of aging in standard technical specifications

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

Orton, R.D.; Allen, R.P.

1995-09-01

As part of the US Nuclear Regulatory Commission`s Nuclear Plant Aging Research Program, Pacific Northwest Laboratory (PNL) evaluated the standard technical specifications for nuclear power plants to determine whether the current surveillance requirements (SRs) were effective in detecting age-related degradation. Nuclear Plant Aging Research findings for selected systems and components were reviewed to identify the stressors and operative aging mechanisms and to evaluate the methods available to detect, differentiate, and trend the resulting aging degradation. Current surveillance and testing requirements for these systems and components were reviewed for their effectiveness in detecting degraded conditions and for potential contributions to prematuremore » degradation. When the current surveillance and testing requirements appeared ineffective in detecting aging degradation or potentially could contribute to premature degradation, a possible deficiency in the SRs was identified that could result in undetected degradation. Based on this evaluation, PNL developed recommendations for inspection, surveillance, trending, and condition monitoring methods to be incorporated in the SRs to better detect age- related degradation of these selected systems and components.« less

Study on degrading graphene oxide in wastewater under different conditions for developing an efficient and economical degradation method.

PubMed

Li, Ting; Zhang, Chao-Zhi; Gu, Chengyue

2017-12-01

With popular application of graphene and graphene oxide (GO), they have been discharged into water. Graphene and GO harm organisms. However, an efficient and economical method for removing graphene and GO in wastewater has seldom been reported. Graphene can be oxidized by hydrogen peroxide to give GO; therefore, degradation of graphene oxide is an important step in the procedure of removal of graphene from water. In this paper, GO degradation via photo-Fenton reaction under different conditions was carried out. Experimental results suggested that GO in wastewater can be efficiently and economically degraded into carbon dioxide and H 2 O when pH value is 3, concentration of H 2 O 2 and FeCl 3 are 35 mM and 5 ppm, respectively. Degradation mechanism of GO was suggested based on UV-vis absorption spectra, scanning electron microscopy, X-ray diffraction and liquid chromatography-mass spectra data of degradation intermediates. This paper suggests an efficient and economical degradation way of GO in wastewater.

Distributed ISAR Subimage Fusion of Nonuniform Rotating Target Based on Matching Fourier Transform.

PubMed

Li, Yuanyuan; Fu, Yaowen; Zhang, Wenpeng

2018-06-04

In real applications, the image quality of the conventional monostatic Inverse Synthetic Aperture Radar (ISAR) for the maneuvering target is subject to the strong fluctuation of Radar Cross Section (RCS), as the target aspect varies enormously. Meanwhile, the maneuvering target introduces nonuniform rotation after translation motion compensation which degrades the imaging performance of the conventional Fourier Transform (FT)-based method in the cross-range dimension. In this paper, a method which combines the distributed ISAR technique and the Matching Fourier Transform (MFT) is proposed to overcome these problems. Firstly, according to the characteristics of the distributed ISAR, the multiple channel echoes of the nonuniform rotation target from different observation angles can be acquired. Then, by applying the MFT to the echo of each channel, the defocused problem of nonuniform rotation target which is inevitable by using the FT-based imaging method can be avoided. Finally, after preprocessing, scaling and rotation of all subimages, the noncoherent fusion image containing all the RCS information in all channels can be obtained. The accumulation coefficients of all subimages are calculated adaptively according to the their image qualities. Simulation and experimental data are used to validate the effectiveness of the proposed approach, and fusion image with improved recognizability can be obtained. Therefore, by using the distributed ISAR technique and MFT, subimages of high-maneuvering target from different observation angles can be obtained. Meanwhile, by employing the adaptive subimage fusion method, the RCS fluctuation can be alleviated and more recognizable final image can be obtained.

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.

A General Accelerated Degradation Model Based on the Wiener Process.

PubMed

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-12-06

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A General Accelerated Degradation Model Based on the Wiener Process

PubMed Central

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-01-01

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses. PMID:28774107

Atomistic modeling of water diffusion in hydrolytic biomaterials.

PubMed

Gautieri, Alfonso; Mezzanzanica, Andrea; Motta, Alberto; Redealli, Alberto; Vesentini, Simone

2012-04-01

One of the most promising applications of hydrolytically degrading biomaterials is their use as drug release carriers. These uses, however, require that the degradation and diffusion of drug are reliably predicted, which is complex to achieve through present experimental methods. Atomistic modeling can help in the knowledge-based design of degrading biomaterials with tuned drug delivery properties, giving insights on the small molecules diffusivity at intermediate states of the degradation process. We present here an atomistic-based approach to investigate the diffusion of water (through which hydrolytic degradation occurs) in degrading bulk models of poly(lactic acid) or PLA. We determine the water diffusion coefficient for different swelling states of the polymeric matrix (from almost dry to pure water) and for different degrees of degradation. We show that water diffusivity is highly influenced by the swelling degree, while little or not influenced by the degradation state. This approach, giving water diffusivity for different states of the matrix, can be combined with diffusion-reaction analytical methods in order to predict the degradation path on longer time scales. Furthermore, atomistic approach can be used to investigate diffusion of other relevant small molecules, eventually leading to the a priori knowledge of degradable biomaterials transport properties, helping the design of the drug delivery systems.

A new approach to accelerated drug-excipient compatibility testing.

PubMed

Sims, Jonathan L; Carreira, Judith A; Carrier, Daniel J; Crabtree, Simon R; Easton, Lynne; Hancock, Stephen A; Simcox, Carol E

2003-01-01

The purpose of this study was to develop a method of qualitatively predicting the most likely degradants in a formulation or probing specific drug-excipient interactions in a significantly shorter time frame than the typical 1 month storage testing. In the example studied, accelerated storage testing of a solid dosage form at 50 degrees C, the drug substance SB-243213-A degraded via the formation of two oxidative impurities. These impurities reached a level of 1% PAR after 3 months. Various stressing methods were examined to try to recreate this degradation and in doing so provide a practical and reliable method capable of predicting drug-excipient interactions. The technique developed was able to mimic the 1-month's accelerated degradation in just 1 hr. The method was suitable for automated analysis, capable of multisample stressing, and ideal for use in drug-excipient compatibility screening.

Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

PubMed

Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

2016-03-30

A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photosensitized degradation of acetaminophen in natural organic matter solutions: The role of triplet states and oxygen.

PubMed

Li, Yanyun; Pan, Yanheng; Lian, Lushi; Yan, Shuwen; Song, Weihua; Yang, Xin

2017-02-01

The photolysis of acetaminophen, a widely used pharmaceutical, in simulated natural organic matter solutions was investigated. The triplet states of natural organic matter ( 3 NOM*) were found to play the dominant role in its photodegradation, while the contributions from hydroxyl radicals and singlet oxygen were negligible. Dissolved oxygen (DO) plays a dual role. From anaerobic to microaerobic (0.5 mg/L DO) conditions, the degradation rate of acetaminophen increased by 4-fold. That suggests the involvement of DO in reactions with the degradation intermediates. With increasing oxygen levels to saturated conditions (26 mg/L DO), the degradation rate became slower, mainly due to DO's quenching effect on 3 NOM*. Superoxide radical (O 2 - ) did not react with acetaminophen directly, but possibly quenched the intermediates to reverse the degradation process. The main photochemical pathways were shown to involve phenoxyl radical and N-radical cations, finally yielding hydroxylated derivatives, dimers and nitrosophenol. A reaction mechanism involving 3 NOM*, oxygen and O 2 - is proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhancement of Fenton processes at initial circumneutral pH for the degradation of norfloxacin with Fe@Fe2O3 core-shell nanomaterials.

PubMed

Liu, Jingyi; Hu, Wenyong; Sun, Maogui; Xiong, Ouyang; Yu, Haibin; Feng, Haopeng; Wu, Xuan; Tang, Lin; Zhou, Yaoyu

2018-06-13

The degradation of norfloxacin by Fenton reagent with core-shell Fe@Fe 2 O 3 nanomaterials was studied under neutral conditions in a closed batch system. Norfloxacin was significantly degraded (90%) in the Fenton system with Fe@Fe 2 O 3 in 30 min at the initial pH 7.0, but slightly degraded in Fenton system without Fe@Fe 2 O 3 under the same experimental conditions. The intermediate products were investigated by gas chromatography-mass spectrometry, and the possible Fenton oxidation pathway of norfloxacin in the presence of Fe@Fe 2 O 3 nanowires was proposed. Electron spin resonance spectroscopy was used to identify and characterize the free radicals generated, and the mechanism for norfloxacin degradation was also revealed. Finally, the reusability and the stability of Fe@Fe 2 O 3 nanomaterials were studied using x-ray diffraction and scanning electron microscope, which indicated that Fe@Fe 2 O 3 is a stable catalyst and can be used repetitively in environmental pollution control.

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

NASA Astrophysics Data System (ADS)

Li, Xiaojuan; Jin, Bo; Huang, Jingwen; Zhang, Qingchun; Peng, Rufang; Chu, Shijin

2018-06-01

In this study, novel ternary Fe2O3/ZnO/ZnFe2O4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.

HPLC & NMR-based forced degradation studies of ifosfamide: The potential of NMR in stability studies.

PubMed

Salman, D; Peron, J-M R; Goronga, T; Barton, S; Swinden, J; Nabhani-Gebara, S

2016-03-01

The aim of this study is to conduct a forced degradation study on ifosfamide under several stress conditions to investigate the robustness of the developed HPLC method. It also aims to provide further insight into the stability of ifosfamide and its degradation profile using both HPLC and NMR. Ifosfamide solutions (20mg/mL; n=15, 20mL) were stressed in triplicate by heating (70°C), under acidic (pH 1 & 4) and alkaline (pH 10 & 12) conditions. Samples were analysed periodically using HPLC and FT-NMR. Ifosfamide was most stable under weakly acidic conditions (pH 4). NMR results suggested that the mechanism of ifosfamide degradation involves the cleavage of the PN bond. For all stress conditions, HPLC was not able to detect ifosfamide degradation products that were detected by NMR. These results suggest that the developed HPLC method for ifosfamide did not detect the degradation products shown by NMR. It is possible that degradation products co-elute with ifosfamide, do not elute altogether or are not amenable to the detection method employed. Therefore, investigation of ifosfamide stability requires additional techniques that do not suffer from the aforementioned shortcomings. Copyright © 2015 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

A Novel Degradation Identification Method for Wind Turbine Pitch System

NASA Astrophysics Data System (ADS)

Guo, Hui-Dong

2018-04-01

It’s difficult for traditional threshold value method to identify degradation of operating equipment accurately. An novel degradation evaluation method suitable for wind turbine condition maintenance strategy implementation was proposed in this paper. Based on the analysis of typical variable-speed pitch-to-feather control principle and monitoring parameters for pitch system, a multi input multi output (MIMO) regression model was applied to pitch system, where wind speed, power generation regarding as input parameters, wheel rotation speed, pitch angle and motor driving currency for three blades as output parameters. Then, the difference between the on-line measurement and the calculated value from the MIMO regression model applying least square support vector machines (LSSVM) method was defined as the Observed Vector of the system. The Gaussian mixture model (GMM) was applied to fitting the distribution of the multi dimension Observed Vectors. Applying the model established, the Degradation Index was calculated using the SCADA data of a wind turbine damaged its pitch bearing retainer and rolling body, which illustrated the feasibility of the provided method.

Modelling accelerated degradation data using Wiener diffusion with a time scale transformation.

PubMed

Whitmore, G A; Schenkelberg, F

1997-01-01

Engineering degradation tests allow industry to assess the potential life span of long-life products that do not fail readily under accelerated conditions in life tests. A general statistical model is presented here for performance degradation of an item of equipment. The degradation process in the model is taken to be a Wiener diffusion process with a time scale transformation. The model incorporates Arrhenius extrapolation for high stress testing. The lifetime of an item is defined as the time until performance deteriorates to a specified failure threshold. The model can be used to predict the lifetime of an item or the extent of degradation of an item at a specified future time. Inference methods for the model parameters, based on accelerated degradation test data, are presented. The model and inference methods are illustrated with a case application involving self-regulating heating cables. The paper also discusses a number of practical issues encountered in applications.

TiO2 used as photocatalyst for rhodamine B degradation under solar radiation

NASA Astrophysics Data System (ADS)

Ariyanti, Dessy; Maillot, Mathilde; Gao, Wei

2017-07-01

Transition metal oxide photocatalysis is a relatively new method representing advanced oxidation process to be applied in industrial wastewater treatment especially for degradation of organic pollutants. We investigate TiO2 as a photocatalyst for the photocatalytic degradation of Rhodamine B (RhB) under simulated sunlight. Various parameters and their effectiveness have been studied. The effects of processing parameters including catalyst loading and feed concentration were investigated; and the degradation pathway was proposed based on the UHPLC-MS analysis. The result showed that a higher kinetic rate can be obtained by employing low catalyst loading and feed concentration, i.e., 0.5 g/L of TiO2 loading and 5 ppm of RhB concentration, respectively. For this particular system, the optimum degradation rate (k) can achieve 0.297/min. The effectiveness of solar light-TiO2 system for RhB degradation shows this method can be used for wastewater treatment.

A Crowdsensing Based Analytical Framework for Perceptional Degradation of OTT Web Browsing.

PubMed

Li, Ke; Wang, Hai; Xu, Xiaolong; Du, Yu; Liu, Yuansheng; Ahmad, M Omair

2018-05-15

Service perception analysis is crucial for understanding both user experiences and network quality as well as for maintaining and optimizing of mobile networks. Given the rapid development of mobile Internet and over-the-top (OTT) services, the conventional network-centric mode of network operation and maintenance is no longer effective. Therefore, developing an approach to evaluate and optimizing users' service perceptions has become increasingly important. Meanwhile, the development of a new sensing paradigm, mobile crowdsensing (MCS), makes it possible to evaluate and analyze the user's OTT service perception from end-user's point of view other than from the network side. In this paper, the key factors that impact users' end-to-end OTT web browsing service perception are analyzed by monitoring crowdsourced user perceptions. The intrinsic relationships among the key factors and the interactions between key quality indicators (KQI) are evaluated from several perspectives. Moreover, an analytical framework of perceptional degradation and a detailed algorithm are proposed whose goal is to identify the major factors that impact the perceptional degradation of web browsing service as well as their significance of contribution. Finally, a case study is presented to show the effectiveness of the proposed method using a dataset crowdsensed from a large number of smartphone users in a real mobile network. The proposed analytical framework forms a valuable solution for mobile network maintenance and optimization and can help improve web browsing service perception and network quality.

Efficient degradation of rhodamine B using modified graphite felt gas diffusion electrode by electro-Fenton process.

PubMed

Tian, Jiangnan; Olajuyin, Ayobami Matthew; Mu, Tingzhen; Yang, Maohua; Xing, Jianmin

2016-06-01

The electro-Fenton (EF) process treatment of 0.1-M (rhodamine B) RhB solution was studied with different graphite cathode materials, and graphite felt (GF) was selected as a promising material in further investigation. Then, the degradation performances of gas diffusion electrode (GDE) and graphite felt (GF) were compared, and GDE was confirmed to be more efficient in RhB removal. The operational parameters such as Fe(2+) dosage and current density were optimized, and comparison among different modified methods-polytetrafluoroethylene-carbon black (PTFE-CB), polytetrafluoroethylene-carbon nanotube (PTFE-CNT), electrodeposition-CB, and electrodeposition-CNT-showed 98.49 % RhB removal by PTFE-CB-modified cathode in 0.05 M Na2SO4 at a current density of 50 A/m(2) and an air flow rate of 1 L/min after 20 min. Meanwhile, after cathode modified by PTFE-CB, the mineralization efficiency and mineralization current efficiency performed absolutely better than the pristine one. Cyclic voltammograms, SEM images, contact angles, and BET surface area were carried out to demonstrate stronger current responses and higher hydrophilicity of GF after modified. The value of biochemical oxygen demand/chemical oxygen demand (BOD5/COD) increased from 0.049 to 0.331 after 90-min treatment, suggesting the solution was biodegradable, and the modified cathode was confirmed to be stable after ten circle runs. Finally, a proposed degradation pathway of RhB was put forward.

The impact of gallium content on degradation, bioactivity, and antibacterial potency of zinc borate bioactive glass.

PubMed

Rahimnejad Yazdi, Alireza; Torkan, Lawrence; Stone, Wendy; Towler, Mark R

2018-01-01

Zinc borate glasses with increasing gallium content (0, 2.5, 5, 10, and 15 Wt % Ga) were synthesized and their degradation, bioactivity in simulated body fluid (SBF), and antibacterial properties were investigated. ICP measurements showed that increased gallium content in the glass resulted in increased gallium ion release and decreased release of other ions. Degradability declined with the addition of gallium, indicating the formation of more symmetric BO 3 units with three bridging oxygens and asymmetric BO 3 units with two bridging oxygens in the glass network as the gallium content in the series increased. The formation of amorphous CaP on the glass surface after 24 h of incubation in SBF was confirmed by SEM, XRD, and FTIR analyses. Finally, antibacterial evaluation of the glasses using the agar disc-diffusion method demonstrated that the addition of gallium increased the antibacterial potency of the glasses against P. aeruginosa (Gram-negative) while decreasing it against S. epidermidis (Gram-positive); considering the ion release trends, this indicates that the gallium ion is responsible for the glasses' antibacterial behavior against P. aeruginosa while the zinc ion controls the antibacterial activity against S. epidermidis. The statistical significance of the observed trends in the measurements were confirmed by applying the Kruskal-Wallis H Test. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 367-376, 2018. © 2017 Wiley Periodicals, Inc.

Stability indicating spectrophotometric and spectrodensitometric methods for the determination of diatrizoate sodium in presence of its degradation product

NASA Astrophysics Data System (ADS)

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

2015-02-01

Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 μg/mL with mean percentage recovery 99.95 ± 0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99 ± 1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 μg/spot, with mean percentage recovery 99.88 ± 0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

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.

Stability-Indicating HPTLC Method for Studying Stress Degradation Behavior of Sulbutiamine HCl.

PubMed

Farid, Nehal F; Abdelwahab, Nada S

2016-04-01

Sulbutiamine (SUL) is an ester of thiazides with neurotropic action. A new stability indicating HPTLC method has been developed and validated for the determination of SUL in the presence of different degradation products. The drug was subjected to different stress conditions following ICH strategy such as hydrolytic degradation (neutral, alkaline and acidic hydrolysis), oxidation, photodegradation and dry heat degradation. The drug demonstrated degradation under all decomposition conditions except neutral hydrolysis and dry heat, where the drug was completely degraded with 0.1 N NaOH, 1 N HCl and 30% H2O2 while it was partially degradaed by 0.1 N HCl, 3% H2O2 and UV light. Structure elucidation of the resulting degradation products was performed using ESI-Q-MS-MS. A well-defined peak for SUL was obtained at Rf = 0.46 and was completely separated from all obtained degradation products. Chromatographic separation was carried out on HPTLC aluminum plates precoated with silica gel 60 F254 using acetone-methylene chloride-ammonia buffer (pH 8.5 ± 0.2) (7:3:0.5, v/v) as a developing system. Densitometric scanning of the separated peaks was performed at 254 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed method. The method was validated with respect to USP guidelines regarding accuracy, precision, specificity, robustness and ruggedness. Good correlation coefficients were achieved in the range of 0.4-5.0 µg/band, and the limit of detection and limit of quantitation were found to be 0.11 and 0.33 µg/band, respectively. The utility of the suggested method was verified by application to Arcalion forte® tablets where no interference from additives was found. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

First derivative ratio spectrophotometric, HPTLC-densitometric, and HPLC determination of nicergoline in presence of its hydrolysis-induced degradation product.

PubMed

Ahmad, Abdel Kader S; Kawy, M Abdel; Nebsen, M

2002-10-15

Three methods are presented for the determination of Nicergoline in presence of its hydrolysis-induced degradation product. The first method was based on measurement of the first derivative of ratio spectra amplitude of Nicergoline at 291 nm. The second method was based on separation of Nicergoline from its degradation product followed by densitometric measurement of the spots at 287 nm. The separation was carried out on HPTLC silica gel F(254) plates, using methanol-ethyl acetate-glacial acetic acid (5:7:3, v/v/v) as mobile phase. The third method was based on high performance liquid chromatographic (HPLC) separation and determination of Nicergoline from its degradation product on a reversed phase, nucloesil C(18) column using a mobile phase of methanol-water-glacial acetic acid (80:20:0.1, v/v/v) with UV detection at 280 nm. Chlorpromazine hydrochloride was used as internal standard. Laboratory prepared mixtures containing different percentages of the degradation product were analysed by the proposed methods and satisfactory results were obtained. These methods have been successfully applied to the analysis of Nicergoline in Sermion tablets. The validities of these methods were ascertained by applying standard addition technique, the mean percentage recovery +/- R.S.D.% was found to be 99.47 +/- 0.752, 100.01 +/- 0.940, 99.75 +/- 0.740 for the first derivative of ratio spectra method, the HPTLC method and the HPLC method, respectively. The proposed methods were statistically compared with the manufacturer's HPLC method of analysis of Nicergoline and no significant difference was found with respect to both precision and accuracy. They have the advantage of being stability indicating. Therefore, they can be used for routine analysis of the drug in quality control laboratories. Copyright 2002 Elsevier Science B.V.

Chemotactic selection of pollutant degrading soil bacteria

DOEpatents

Hazen, T.C.

1991-03-04

A method is described for identifying soil microbial strains which may be bacterial degraders of pollutants. This method includes: Placing a concentration of a pollutant in a substantially closed container; placing the container in a sample of soil for a period of time ranging from one minute to several hours; retrieving the container and collecting its contents; microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to innoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

[Establishment and evaluation of an in vitro method for neutrophil extracellular trap generation and degradation].

PubMed

Li, Jinlong; Zhang, Yidan; Zhou, Xin; Ji, Wenjie; Zhao, Jihong; Wei, Luqing; Li, Yuming

2014-09-01

To evaluate a novel method for in vitro generation and degradation of neutrophil extracellular traps (NETs), which are a newly recognized structure that is involved in the pathogenesis of autoimmune diseases and thrombosis. Neutrophils from peripheral blood of healthy donors were obtained by Ficoll-Histopaque gradient separation. NET release was initiated by phorbol myristate acetate (PMA) and validated by immunofluorescence staining and agarose gel electrophoresis. NETs degraded by DNase I and healthy human plasma were quantified by fluorescence spectrometry after staining with PicoGreen. HE staining showed that the purity of neutrophils was up to 95% after Ficoll-Histopaque gradient separation. NET immunofluorescent staining revealed that the network structure was mainly composed of DNA and histones, with molecular length more than 10 kb as demonstrated by agarose gel electrophoresis. Moreover, both DNase and healthy human plasma could induce the degradation of NETs, in varying degrees. This work established an efficient method for in vitro generation and degradation of human NETs.

A LDR-PCR approach for multiplex polymorphisms genotyping of severely degraded DNA with fragment sizes <100 bp.

PubMed

Zhang, Zhen; Wang, Bao-Jie; Guan, Hong-Yu; Pang, Hao; Xuan, Jin-Feng

2009-11-01

Reducing amplicon sizes has become a major strategy for analyzing degraded DNA typical of forensic samples. However, amplicon sizes in current mini-short tandem repeat-polymerase chain reaction (PCR) and mini-sequencing assays are still not suitable for analysis of severely degraded DNA. In this study, we present a multiplex typing method that couples ligase detection reaction with PCR that can be used to identify single nucleotide polymorphisms and small-scale insertion/deletions in a sample of severely fragmented DNA. This method adopts thermostable ligation for allele discrimination and subsequent PCR for signal enhancement. In this study, four polymorphic loci were used to assess the ability of this technique to discriminate alleles in an artificially degraded sample of DNA with fragment sizes <100 bp. Our results showed clear allelic discrimination of single or multiple loci, suggesting that this method might aid in the analysis of extremely degraded samples in which allelic drop out of larger fragments is observed.

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

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

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.

Degradation Factor Approach for Impacted Composite Structural Assessment: MSFC Center Director's Discretionary Fund Final Report, Project No. 96-17

NASA Technical Reports Server (NTRS)

Ortega, R.; Price, J. M.; Fox, D.

2000-01-01

This technical memorandum documents the results of the research to develop a concept for assessing the structural integrity of impacted composite structures using the strength degradation factor in conjunction with available finite element tools. For this purpose, a literature search was conducted, a plan for conducting impact testing on two laminates was developed, and a finite element model of the impact process was created. Specimens for the impact testing were fabricated to support the impact testing plan.

Bioconversion of lutein by Enterobacter hormaechei to form a new compound, 8-methyl-α-ionone.

PubMed

Zhong, Guifang; Wang, Fangfang; Sun, Jianhong; Ye, Jianbin; Mao, Duobin; Ma, Ke; Yang, Xuepeng

2017-07-01

To investigate the final product of the bioconversion of lutein by a novel lutein-degrading bacterium, Enterobacter hormaechei A20, and the kinetics of the process. A new product, 8-methyl-α-ionone, was resolved by GC-MS. The compound was further identified by NMR. A conversion yield of 90% was achieved by E. hormaechei in 36 h with 10 g lutein l -1 . This is the first report of the bioconversion of lutein to form 8-methyl-α-ionone. A degradation pathway is proposed.

Comments on the interaction of materials with atomic oxygen

NASA Technical Reports Server (NTRS)

Torre, Larry P.; Pippin, H. Gary

1987-01-01

An explanation of the relative resistance of various materials to attack by atomic oxygen is presented. Data from both ground based and on-orbit experiments is interpreted. The results indicate the importance of bond strengths, size and structure of pendant groups, and fluorination to the resistance of certain polymers to atomic oxygen. A theory which provides a partial explanation of the degradation of materials in low Earth orbit due to surface recombination of oxygen atoms is also included. Finally, a section commenting on mechanisms of material degradation is provided.

Nondestructive testing methods to predict effect of degradation on wood : a critical assessment

Treesearch

J. Kaiserlik

1978-01-01

Results are reported for an assessment of methods for predicting strength of wood, wood-based, or related material. Research directly applicable to nondestructive strength prediction was very limited. In wood, strength prediction research is limited to vibration decay, wave attenuation, and multiparameter "degradation models." Nonwood methods with potential...

Ratio manipulating spectrophotometry versus chemometry as stability indicating methods for cefquinome sulfate determination

NASA Astrophysics Data System (ADS)

Yehia, Ali M.; Arafa, Reham M.; Abbas, Samah S.; Amer, Sawsan M.

2016-01-01

Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photo-degradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.0-40.0 μg mL- 1. Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photo-degradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and cost-effective compared with the manufacturer's RP-HPLC method.

Flow Visualization of Density in a Cryogenic Wind Tunnel Using Planar Rayleigh and Raman Scattering

NASA Technical Reports Server (NTRS)

Herring, Gregory C.; Shirinzadeh, Behrooz

2002-01-01

Using a pulsed Nd:YAG laser (532 nm) and a gated, intensified charge-coupled device, planar Rayleigh and Raman scattering techniques have been used to visualize the unseeded Mach 0.2 flow density in a 0.3-meter transonic cryogenic wind tunnel. Detection limits are determined for density measurements by using both unseeded Rayleigh and Raman (N2 vibrational) methods. Seeding with CO2 improved the Rayleigh flow visualization at temperatures below 150 K. The seeded Rayleigh version was used to demonstrate the observation of transient flow features in a separated boundary layer region, which was excited with an oscillatory jet. Finally, a significant degradation of the laser light sheet, in this cryogenic facility, is discussed.

Processing of waste material of radix physochlainae for preparation of fine chemicals after extraction

NASA Astrophysics Data System (ADS)

He, A.; Yohannes, A.; Feng, X. T.; Yao, S.

2017-02-01

Waste residues of Chinese traditional medicine radix physochlainae (Huashanshen) contain a large amount of hemicelluloses after extraction. After the removal of the cellulose and lignin, main components of the solution are different degree of hydrolysis products of hemicelluloses. In the degradation process, hemicelluloses firstly become pentose, and then pentose loses 3 molecules of water and turns into furfural. This study explored a series of conditions of the method; finally the yield of furfural can reach 8.5% (calculated with the weight of raw residues) under the condition of pH of 0.2-0.3, temperature of 104-106°C, hydrolysis duration for 10 minutes. Furfural can be further processed to be resin materials.

Advances in Instrumental Analysis of Brominated Flame Retardants: Current Status and Future Perspectives

PubMed Central

2014-01-01

This review aims to highlight the recent advances and methodological improvements in instrumental techniques applied for the analysis of different brominated flame retardants (BFRs). The literature search strategy was based on the recent analytical reviews published on BFRs. The main selection criteria involved the successful development and application of analytical methods for determination of the target compounds in various environmental matrices. Different factors affecting chromatographic separation and mass spectrometric detection of brominated analytes were evaluated and discussed. Techniques using advanced instrumentation to achieve outstanding results in quantification of different BFRs and their metabolites/degradation products were highlighted. Finally, research gaps in the field of BFR analysis were identified and recommendations for future research were proposed. PMID:27433482

Pectin-based oral drug delivery to the colon.

PubMed

Sande, Sverre Arne

2005-05-01

This review presents an overview of studies concerning oral formulations intended for site-specific drug delivery to the colon with pectin as the main excipient. The biological aspects covered include gastrointestinal transit and the enzymatic degradation of pectin. Scintigraphic methods demonstrating the functionality of pectin formulations are discussed. The main focus is on the various formulations reported, including matrix tablets, multiparticulate formulations as pellets and hydrogel beads, and pectin-based coatings. Also included is an evaluation of common excipients employed to improve colon specificity by crosslinking or increasing the hydrophobicity. Finally, properties of the pectin molecules that are important for successful formulations are examined. The conclusion is that the studies found in the literature provide an excellent platform for the development of pectin-based colon delivery systems.

The effect of accelerated aging on the wear of UHMWPE.

PubMed

Sakoda, H; Fisher, J; Lu, S; Buchanan, F

2001-01-01

Oxidative degradation of UHMWPE has been found to be a cause of elevated wear rate of the polymer in total joint replacement leading to failure of these devices. In order to evaluate long term stability of polymers, various accelerated aging methods have been developed. In this study, wear rates of shelf aged UHMWPE and "accelerated aged" UHMWPE were compared using a multi-directional pin-on-plate wear test machine in order to evaluate the effect of the accelerated aging on wear. Wear factors of the aged materials were found to depend on their density, which is a measure of oxidation level. Finally, accelerated aging was calibrated against shelf aging in terms of wear rate. Copyright 2001 Kluwer Academic Publishers

A method for addressing differences in concentrations of fipronil and three degradates obtained by two different laboratory methods

USGS Publications Warehouse

Crawford, Charles G.; Martin, Jeffrey D.

2017-07-21

In October 2012, the U.S. Geological Survey (USGS) began measuring the concentration of the pesticide fipronil and three of its degradates (desulfinylfipronil, fipronil sulfide, and fipronil sulfone) by a new laboratory method using direct aqueous-injection liquid chromatography tandem mass spectrometry (DAI LC–MS/MS). This method replaced the previous method—in use since 2002—that used gas chromatography/mass spectrometry (GC/MS). The performance of the two methods is not comparable for fipronil and the three degradates. Concentrations of these four chemical compounds determined by the DAI LC–MS/MS method are substantially lower than the GC/MS method. A method was developed to correct for the difference in concentrations obtained by the two laboratory methods based on a methods comparison field study done in 2012. Environmental and field matrix spike samples to be analyzed by both methods from 48 stream sites from across the United States were sampled approximately three times each for this study. These data were used to develop a relation between the two laboratory methods for each compound using regression analysis. The relations were used to calibrate data obtained by the older method to the new method in order to remove any biases attributable to differences in the methods. The coefficients of the equations obtained from the regressions were used to calibrate over 16,600 observations of fipronil, as well as the three degradates determined by the GC/MS method retrieved from the USGS National Water Information System. The calibrated values were then compared to over 7,800 observations of fipronil and to the three degradates determined by the DAI LC–MS/MS method also retrieved from the National Water Information System. The original and calibrated values from the GC/MS method, along with measures of uncertainty in the calibrated values and the original values from the DAI LC–MS/MS method, are provided in an accompanying data release.

Research study on high energy radiation effect and environment solar cell degradation methods

NASA Technical Reports Server (NTRS)

Horne, W. E.; Wilkinson, M. C.

1974-01-01

The most detailed and comprehensively verified analytical model was used to evaluate the effects of simplifying assumptions on the accuracy of predictions made by the external damage coefficient method. It was found that the most serious discrepancies were present in heavily damaged cells, particularly proton damaged cells, in which a gradient in damage across the cell existed. In general, it was found that the current damage coefficient method tends to underestimate damage at high fluences. An exception to this rule was thick cover-slipped cells experiencing heavy degradation due to omnidirectional electrons. In such cases, the damage coefficient method overestimates the damage. Comparisons of degradation predictions made by the two methods and measured flight data confirmed the above findings.

An improved predictive functional control method with application to PMSM systems

NASA Astrophysics Data System (ADS)

Li, Shihua; Liu, Huixian; Fu, Wenshu

2017-01-01

In common design of prediction model-based control method, usually disturbances are not considered in the prediction model as well as the control design. For the control systems with large amplitude or strong disturbances, it is difficult to precisely predict the future outputs according to the conventional prediction model, and thus the desired optimal closed-loop performance will be degraded to some extent. To this end, an improved predictive functional control (PFC) method is developed in this paper by embedding disturbance information into the system model. Here, a composite prediction model is thus obtained by embedding the estimated value of disturbances, where disturbance observer (DOB) is employed to estimate the lumped disturbances. So the influence of disturbances on system is taken into account in optimisation procedure. Finally, considering the speed control problem for permanent magnet synchronous motor (PMSM) servo system, a control scheme based on the improved PFC method is designed to ensure an optimal closed-loop performance even in the presence of disturbances. Simulation and experimental results based on a hardware platform are provided to confirm the effectiveness of the proposed algorithm.

Robust Arm and Hand Tracking by Unsupervised Context Learning

PubMed Central

Spruyt, Vincent; Ledda, Alessandro; Philips, Wilfried

2014-01-01

Hand tracking in video is an increasingly popular research field due to the rise of novel human-computer interaction methods. However, robust and real-time hand tracking in unconstrained environments remains a challenging task due to the high number of degrees of freedom and the non-rigid character of the human hand. In this paper, we propose an unsupervised method to automatically learn the context in which a hand is embedded. This context includes the arm and any other object that coherently moves along with the hand. We introduce two novel methods to incorporate this context information into a probabilistic tracking framework, and introduce a simple yet effective solution to estimate the position of the arm. Finally, we show that our method greatly increases robustness against occlusion and cluttered background, without degrading tracking performance if no contextual information is available. The proposed real-time algorithm is shown to outperform the current state-of-the-art by evaluating it on three publicly available video datasets. Furthermore, a novel dataset is created and made publicly available for the research community. PMID:25004155

Super-resolved refocusing with a plenoptic camera

NASA Astrophysics Data System (ADS)

Zhou, Zhiliang; Yuan, Yan; Bin, Xiangli; Qian, Lulu

2011-03-01

This paper presents an approach to enhance the resolution of refocused images by super resolution methods. In plenoptic imaging, we demonstrate that the raw sensor image can be divided to a number of low-resolution angular images with sub-pixel shifts between each other. The sub-pixel shift, which defines the super-resolving ability, is mathematically derived by considering the plenoptic camera as equivalent camera arrays. We implement simulation to demonstrate the imaging process of a plenoptic camera. A high-resolution image is then reconstructed using maximum a posteriori (MAP) super resolution algorithms. Without other degradation effects in simulation, the super resolved image achieves a resolution as high as predicted by the proposed model. We also build an experimental setup to acquire light fields. With traditional refocusing methods, the image is rendered at a rather low resolution. In contrast, we implement the super-resolved refocusing methods and recover an image with more spatial details. To evaluate the performance of the proposed method, we finally compare the reconstructed images using image quality metrics like peak signal to noise ratio (PSNR).

Application of contact glow discharge electrolysis method for degradation of batik dye waste Remazol Red by the addition of Fe2+ ion

NASA Astrophysics Data System (ADS)

Saksono, Nelson; Puspita, Indah; Sukreni, Tulus

2017-03-01

Contact Glow Discharge Electrolysis (CGDE) has been shown to degrade much weight organic compounds such as dyes because the production of hydroxil radical (•OH) is excess. This research aims to degrade batik dye waste Remazol Red, using CGDE method with the addition of Fe2+ ion. The addition of iron salt compounds has proven to increase process efficiency. Dye degradation is known by measure its absorbances with Spectrophotometer UV-Vis. The result of study showed that percentage degradation was 99.92% in 20 minutes which obtained by using Na2SO4 0.01 M, with addition FeSO4 0,1 gram, applied voltage 860 volt, and 1 wolfram anode 5 mm depth.

Biochemical pathways and enhanced degradation of di-n-octyl phthalate (DOP) in sequencing batch reactor (SBR) by Arthrobacter sp. SLG-4 and Rhodococcus sp. SLG-6 isolated from activated sludge.

PubMed

Zhang, Ke; Liu, Yihao; Chen, Qiang; Luo, Hongbing; Zhu, Zhanyuan; Chen, Wei; Chen, Jia; Mo, You

2018-04-01

Two bacterial strains designated as Arthrobacter sp. SLG-4 and Rhodococcus sp. SLG-6, capable of utilizing di-n-octyl phthalate (DOP) as sole source of carbon and energy, were isolated from activated sludge. The analysis of DOP degradation intermediates indicated Arthrobacter sp. SLG-4 could completely degrade DOP. Whereas DOP could not be mineralized by Rhodococcus sp. SLG-6 and the final metabolic product was phthalic acid (PA). The proposed DOP degradation pathway by Arthrobacter sp. SLG-4 was that strain SLG-4 initially transformed DOP to PA via de-esterification pathway, and then PA was metabolized to protocatechuate acid and eventually converted to tricarboxylic acid (TCA) cycle through meta-cleavage pathway. Accordingly, Phthalate 3,4-dioxygenase genes (phtA) responsible for PA degradation were successfully detected in Arthrobacter sp. SLG-4 by real-time quantitative PCR (q-PCR). q-PCR analysis demonstrated that the quantity of phthalate 3,4-dioxygenase was positively correlated to DOP degradation in SBRs. Bioaugmentation by inoculating DOP-degrading bacteria effectively shortened the start-up of SBRs and significantly enhanced DOP degradation in bioreactors. More than 91% of DOP (500 mg L -1 ) was removed in SBR bioaugmented with bacterial consortium, which was double of the control SBR. This study suggests bioaugmentation is an effective and feasible technique for DOP bioremediation in practical engineering.

Methods of degrading napalm B

DOEpatents

Tyndall, Richard L.; Vass, Arpad

1995-01-01

Methods of degrading napalm and/or trinitrotoluene involve contacting the waste with specific intra-amoebic isolates of ATCC 40908 and/or dispersants derived therefrom. Useful isolates include is deposited as ATCC 77529, NAP-1 deposited as ATCC 77526 and 13 deposited as ATCC 77527.

Observation method to predict meander migration and vertical degradation of rivers.

DOT National Transportation Integrated Search

2014-05-01

Meander migration and vertical degradation of river bed are processes that have been studied for years. : Different methods have been proposed to make predictions of the behavior of rivers with respect to these : processes. These two erosion controll...

Methods of degrading napalm B

DOEpatents

Tyndall, R.L.; Vass, A.

1995-09-12

Methods of degrading napalm and/or trinitrotoluene involve contacting the waste with specific intra-amoebic isolates of ATCC 40908 and/or dispersants derived therefrom. Useful isolates are deposited as ATCC 77529, NAP-1 deposited as ATCC 77526 and 13 deposited as ATCC 77527.

Methacrylate based cross-linkers for improved thermomechanical properties and retention of radiation detection response in plastic scintillators

NASA Astrophysics Data System (ADS)

Mahl, Adam; Lim, Allison; Latta, Joseph; Yemam, Henok A.; Greife, Uwe; Sellinger, Alan

2018-03-01

Pulse shape discrimination (PSD) is an important method that can efficiently sort and separate neutron and gamma radiation signals. PSD is currently achieved in plastic scintillators by over-doping poly(vinyl toluene) (PVT) matrices with fluorescent molecules. Meaningful separation of the signals requires addition of >20 wt% 2,5-diphenyloxazole (PPO) fluor in PVT. At these concentrations PPO acts as a plasticizer, negatively affecting the physical properties of the final plastic such as hardness, machinability, and thermomechanical stability. This work addresses these issues by implementing a cost-effective solution using cross-linking chemistry via commercially available bisphenol A dimethacrylate (BPA-DM), and a synthesized fluorinated analogue. Both improve the physical properties of over-doped PPO based plastic scintillators without degrading the measured light yield or PSD and Figure of Merit (FoM). In addition, the fluorinated analogue appears to enhance the hydrophobicity of the surface of the plastic scintillators, which may improve the scintillators' resistance to water diffusion and subsequent radiation response degradation. The new formulations improve the feasibility of widely deploying long lifetime PSD capable plastic scintillators in large area coverage assemblies.

Continuous feed, on-site composting of kitchen garbage.

PubMed

Hwang, Eung-Ju; Shin, Hang-Sik; Tay, Joo-Hwa

2002-04-01

Kitchen garbage generated at a school cafeteria was treated and stabilised in a controlled on-site composting unit for volume reduction and on-site utilisation of processed garbage. The on-site composter was fed with the garbage on a daily basis during the two-months experimental period. Compost was not removed from the unit but was entirely reused as a bulking agent in order to minimise the need for additional bulking agent and compost handling. Performance of the composter tinder this condition was investigated. Most of the easily degradable organic matter (EDM) in the garbage was biodegraded rapidly, and the final product had a low content of EDM. Lipids, total sugar, and hemi-cellulose were degraded 96%, 81%, and 66% respectively. Free air space (FAS) was higher than 0.5 all the time, so accumulation of dry matter in the unit was not significant in reducing reaction efficiency. Other reaction parameters such as pH and MC were kept within a suitable range; however, it was advisable to maintain MC at over 46%. As a result, this method of operation was able to stabilise the garbage with low sawdust demand and little compost production.

GOCI image enhancement using an MTF compensation technique for coastal water applications.

PubMed

Oh, Eunsong; Choi, Jong-Kuk

2014-11-03

The Geostationary Ocean Color Imager (GOCI) is the first optical sensor in geostationary orbit for monitoring the ocean environment around the Korean Peninsula. This paper discusses on-orbit modulation transfer function (MTF) estimation with the pulse-source method and its compensation results for the GOCI. Additionally, by analyzing the relationship between the MTF compensation effect and the accuracy of the secondary ocean product, we confirmed the optimal MTF compensation parameter for enhancing image quality without variation in the accuracy. In this study, MTF assessment was performed using a natural target because the GOCI system has a spatial resolution of 500 m. For MTF compensation with the Wiener filter, we fitted a point spread function with a Gaussian curve controlled by a standard deviation value (σ). After a parametric analysis for finding the optimal degradation model, the σ value of 0.4 was determined to be an optimal indicator. Finally, the MTF value was enhanced from 0.1645 to 0.2152 without degradation of the accuracy of the ocean color product. Enhanced GOCI images by MTF compensation are expected to recognize small-scale ocean products in coastal areas with sharpened geometric performance.

Analysis of methane biodegradation by Methylosinus trichosporium OB3b

PubMed Central

Rodrigues, Andréa dos Santos; Salgado, Belkis Valdman e Andréa Medeiros

2009-01-01

The microbial oxidation of methane in the atmosphere is performed by methanotrophic bacteria that use methane as a unique source of carbon and energy. The objective of this work consisted of the investigation of the best conditions of methane biodegradation by methanotrophic bacteria Methylosinus trichosporium OB3b that oxidize it to carbon dioxide, and the use of these microorganisms in monitoring methods for methane. The results showed that M. trichosporium OB3b was capable to degrade methane in a more effective way with an initial microorganism concentration of 0.0700 g.L-1, temperature of 30ºC, pH 6.5 and using 1.79 mmol of methane. In these same conditions, there was no bacterial growth when 2.69 mmol of methane was used. The specific rate of microorganism growth, the conversion factor, the efficiency and the volumetric productivity, for the optimized conditions of biodegradation were, respectively, 0.0324 h-1, 0.6830 gcells/gCH4, 73.73% and 2.7732.10-3 gcells/L.h. The final product of methane microbiological degradation, carbon dioxide, was quantified through the use of a commercial electrode, and, through this, the grade of methane conversion in carbon dioxide was calculated. PMID:24031362

Analytical determination of propeller performance degradation due to ice accretion

NASA Technical Reports Server (NTRS)

Miller, T. L.

1986-01-01

A computer code has been developed which is capable of computing propeller performance for clean, glaze, or rime iced propeller configurations, thereby providing a mechanism for determining the degree of performance degradation which results from a given icing encounter. The inviscid, incompressible flow field at each specified propeller radial location is first computed using the Theodorsen transformation method of conformal mapping. A droplet trajectory computation then calculates droplet impingement points and airfoil collection efficiency for each radial location, at which point several user-selectable empirical correlations are available for determining the aerodynamic penalities which arise due to the ice accretion. Propeller performance is finally computed using strip analysis for either the clean or iced propeller. In the iced mode, the differential thrust and torque coefficient equations are modified by the drag and lift coefficient increments due to ice to obtain the appropriate iced values. Comparison with available experimental propeller icing data shows good agreement in several cases. The code's capability to properly predict iced thrust coefficient, power coefficient, and propeller efficiency is shown to be dependent on the choice of empirical correlation employed as well as proper specification of radial icing extent.

A combined chitosan/nano-size hydroxyapatite system for the controlled release of icariin.

PubMed

Fan, Junjun; Bi, Long; Wu, Tao; Cao, Liangguo; Wang, Dexin; Nan, Kaihui; Chen, Jingdi; Jin, Dan; Jiang, Shan; Pei, Guoxian

2012-02-01

Icariin, a plant-derived flavonol glycoside, has been proved as an osteoinductive agent for bone regeneration. For this reason, we developed an icariin-loaded chitosan/nano-sized hydroxyapatite (IC-CS/HA) system which controls the release kinetics of icariin to enhance bone repairing. First, by Fourier transform infrared spectroscopy, we found that icariin was stable in the system developed without undergoing any chemical changes. On the other hand, X-ray diffraction, scanning electron microscopy and mechanical test revealed that the introduction of icariin did not remarkably change the phase, morphology, porosity and mechanical strength of the CS/HA composite. Then the hydrolytic degradation and drug release kinetics in vitro were investigated by incubation in phosphate buffered saline solution. The results indicated that the icariin was released in a temporally controlled manner and the release kinetics could be governed by degradation of both chitosan and hydroxyapatite matrix. Finally the in vitro bioactivity assay revealed that the loaded icariin was biologically active as evidenced by stimulation of bone marrow derived stroma cell alkaline phosphatase activity and formation of mineralized nodules. This successful IC-CS/HA system offers a new delivery method of osteoinductive agents and a useful scaffold design for bone regeneration.

Quality by design approach for the separation of naproxcinod and its related substances by fused core particle technology column.

PubMed

Inugala, Ugandar Reddy; Pothuraju, Nageswara Rao; Vangala, Ranga Reddy

2013-01-01

This paper describes the development of a rapid, novel, stability-indicating gradient reversed-phase high-performance liquid chromatographic method and associated system suitability parameters for the analysis of naproxcinod in the presence of its related substances and degradents using a quality-by-design approach. All of the factors that affect the separation of naproxcinod and its impurities and their mutual interactions were investigated and robustness of the method was ensured. The method was developed using an Ascentis Express C8 150 × 4.6 mm, 2.7 µm column with a mobile phase containing a gradient mixture of two solvents. The eluted compounds were monitored at 230 nm, the run time was 20 min within which naproxcinod and its eight impurities were satisfactorily separated. Naproxcinod was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Naproxcinod was found to degrade significantly in acidic and basic conditions and to be stable in thermal, photolytic, oxidative and aqueous degradation conditions. The degradation products were satisfactorily resolved from the primary peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness.

Gravimetric screening method for fungal decay of paper: inoculation with Trametes versicolor.

PubMed

Råberg, Ulrika; Hafrén, Jonas

2009-10-01

The European standard test EN 113 for fungal degradation of solid wood has been adapted for degradation of paper by white rot fungus (Trametes versicolor). Fungal degradation of paper sheets may potentially be used for screening different wood preservatives on paper instead of solid wood. The paper samples showed higher relative mass losses compared to wood, and samples pretreated with boric acid, copper sulfate and polymerized linseed oil were successfully tested for biodegradation using the paper sheet method. The results on paper degradation were compared with wood, both as wood blocks (according to standard test) and wood cut in sections forming layered structures mimicking paper layers.

Analytical method development of nifedipine and its degradants binary mixture using high performance liquid chromatography through a quality by design approach

NASA Astrophysics Data System (ADS)

Choiri, S.; Ainurofiq, A.; Ratri, R.; Zulmi, M. U.

2018-03-01

Nifedipin (NIF) is a photo-labile drug that easily degrades when it exposures a sunlight. This research aimed to develop of an analytical method using a high-performance liquid chromatography and implemented a quality by design approach to obtain effective, efficient, and validated analytical methods of NIF and its degradants. A 22 full factorial design approach with a curvature as a center point was applied to optimize of the analytical condition of NIF and its degradants. Mobile phase composition (MPC) and flow rate (FR) as factors determined on the system suitability parameters. The selected condition was validated by cross-validation using a leave one out technique. Alteration of MPC affected on time retention significantly. Furthermore, an increase of FR reduced the tailing factor. In addition, the interaction of both factors affected on an increase of the theoretical plates and resolution of NIF and its degradants. The selected analytical condition of NIF and its degradants has been validated at range 1 – 16 µg/mL that had good linearity, precision, accuration and efficient due to an analysis time within 10 min.

Dissecting the Molecular Pathway Involved in PLK2 Kinase-mediated α-Synuclein-selective Autophagic Degradation.

PubMed

Dahmene, Manel; Bérard, Morgan; Oueslati, Abid

2017-03-03

Increasing lines of evidence support the causal link between α-synuclein (α-syn) accumulation in the brain and Parkinson's disease (PD) pathogenesis. Therefore, lowering α-syn protein levels may represent a viable therapeutic strategy for the treatment of PD and related disorders. We recently described a novel selective α-syn degradation pathway, catalyzed by the activity of the Polo-like kinase 2 (PLK2), capable of reducing α-syn protein expression and suppressing its toxicity in vivo However, the exact molecular mechanisms underlying this degradation route remain elusive. In the present study we report that among PLK family members, PLK3 is also able to catalyze α-syn phosphorylation and degradation in living cells. Using pharmacological and genetic approaches, we confirmed the implication of the macroautophagy on PLK2-mediated α-syn turnover, and our observations suggest a concomitant co-degradation of these two proteins. Moreover, we showed that the N-terminal region of α-syn is important for PLK2-mediated α-syn phosphorylation and degradation and is implicated in the physical interaction between the two proteins. We also demonstrated that PLK2 polyubiquitination is important for PLK2·α-syn protein complex degradation, and we hypothesize that this post-translational modification may act as a signal for the selective recognition by the macroautophagy machinery. Finally, we observed that the PD-linked mutation E46K enhances PLK2-mediated α-syn degradation, suggesting that this mutated form is a bona fide substrate of this degradation pathway. In conclusion, our study provides a detailed description of the new degradation route of α-syn and offers new opportunities for the development of therapeutic strategies aiming to reduce α-syn protein accumulation and toxicity. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The impact of the hydroxyl radical photochemical sources on the rivastigmine drug transformation in mimic and natural waters.

PubMed

Passananti, Monica; Temussi, Fabio; Iesce, Maria Rosaria; Mailhot, Gilles; Brigante, Marcello

2013-09-15

In this paper we investigated the degradation of the rivastigmine drug induced by hydroxyl radical in synthetic and natural waters focusing on both reactivity and photoproducts identification. The hydroxyl radical formation rate was quantified by using terephthalic acid as trapping molecule and it was related with the rivastigmine degradation rate. The second order rate constant between hydroxyl radical and rivastigmine was estimated to be ≈ 5.8 × 10(9) M(-1) s(-1). Irradiation of rivastigmine in three natural waters (rain, lake and river) and comparison with degradation rates observed in synthetic solutions using nitrite, nitrate and hydrogen peroxide suggest that, in addition to hydroxyl radical, also nitroderived radicals (NO/NO2) are responsible for the pollutant degradation in natural media. In fact, the evaluated degradation rates in three natural waters are greatly higher than those estimated considering only the reactivity with photogenerated hydroxyl radical. Using nitrites and nitrates as photochemical OH source, the rivastigmine degradation cannot be described considering only the hydroxyl radical reactivity suggesting that NO and NO2 radicals could play a key role during indirect degradation. Moreover main degradation products have been identified by means of HPLC-MS. Hydroxylation of the aromatic ring as well as carbamate and amino chain oxidation were suggested as main reaction mechanisms, but also nitroderived compounds were characterized. Finally polychromatic irradiations of three rivastigmine doped natural waters (rain, river and lake) underlined the role of the indirect degradation that needs to be considered when direct degradation of selected pollutants is negligible under environmental-like conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Next Generation Wiring

NASA Technical Reports Server (NTRS)

Medelius, Petro; Jolley, Scott; Fitzpatrick, Lilliana; Vinje, Rubiela; Williams, Martha; Clayton, LaNetra; Roberson, Luke; Smith, Trent; Santiago-Maldonado, Edgardo

2007-01-01

Wiring is a major operational component on aerospace hardware that accounts for substantial weight and volumetric space. Over time wire insulation can age and fail, often leading to catastrophic events such as system failure or fire. The next generation of wiring must be reliable and sustainable over long periods of time. These features will be achieved by the development of a wire insulation capable of autonomous self-healing that mitigates failure before it reaches a catastrophic level. In order to develop a self-healing insulation material, three steps must occur. First, methods of bonding similar materials must be developed that are capable of being initiated autonomously. This process will lead to the development of a manual repair system for polyimide wire insulation. Second, ways to initiate these bonding methods that lead to materials that are similar to the primary insulation must be developed. Finally, steps one and two must be integrated to produce a material that has no residues from the process that degrades the insulating properties of the final repaired insulation. The self-healing technology, teamed with the ability to identify and locate damage, will greatly improve reliability and safety of electrical wiring of critical systems. This paper will address these topics, discuss the results of preliminary testing, and remaining development issues related to self-healing wire insulation.

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

Sun, Shibin; College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061; Chang, Xueting, E-mail: xuetingchang@yahoo.cn

Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmet-Teller analysis of nitrogen sorptometer, and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-dopedmore » tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: Black-Right-Pointing-Pointer Co-doped W{sub 18}O{sub 49} mesocrystals were synthesized using a solvothermal method. Black-Right-Pointing-Pointer The Co doping has obvious effect on the morphology of the final mesocrystals. Black-Right-Pointing-Pointer The Co-doped W{sub 18}O{sub 49} exhibited superior photocatalytic activity to the undoped W{sub 18}O{sub 49}.« less

Path planning and parameter optimization of uniform removal in active feed polishing

NASA Astrophysics Data System (ADS)

Liu, Jian; Wang, Shaozhi; Zhang, Chunlei; Zhang, Linghua; Chen, Huanan

2015-06-01

A high-quality ultrasmooth surface is demanded in short-wave optical systems. However, the existing polishing methods have difficulties meeting the requirement on spherical or aspheric surfaces. As a new kind of small tool polishing method, active feed polishing (AFP) could attain a surface roughness of less than 0.3 nm (RMS) on spherical elements, although AFP may magnify the residual figure error or mid-frequency error. The purpose of this work is to propose an effective algorithm to realize uniform removal of the surface in the processing. At first, the principle of the AFP and the mechanism of the polishing machine are introduced. In order to maintain the processed figure error, a variable pitch spiral path planning algorithm and the dwell time-solving model are proposed. For suppressing the possible mid-frequency error, the uniformity of the synthesis tool path, which is generated by an arbitrary point at the polishing tool bottom, is analyzed and evaluated, and the angular velocity ratio of the tool spinning motion to the revolution motion is optimized. Finally, an experiment is conducted on a convex spherical surface and an ultrasmooth surface is finally acquired. In conclusion, a high-quality ultrasmooth surface can be successfully obtained with little degradation of the figure and mid-frequency errors by the algorithm.

Differential degradation patterns of photovoltaic backsheets at the array level

DOE PAGES

Fairbrother, Andrew; Boyd, Matthew; Lyu, Yadong; ...

2018-02-04

There are relatively few field studies on the degradation of non-fluoropolymer-based backsheets, and understanding their in-field behavior is critical for further development of such products. In this paper, backsheet degradation of modules with one of these new types of backsheets (polyethylene naphthalate (PEN)-based) was documented at a four-year old utility-scale array located in Maryland (USA). Visual inspection, colorimetry, glossimetry, and Fourier-transform infrared spectroscopy (FTIR) revealed highly varied properties depending on module position within the array. Specifically, modules near the edge of the array and with higher mounting elevations underwent greater amounts of backsheet degradation, as indicated by yellowing and gloss-loss.more » The reason for these unique degradation patterns were differential backside exposure conditions, especially of ultraviolet light. This was strongly influenced by the array design, including array structural and environmental factors, such as module spacing and ground cover, respectively. Within the array, no clear link between backsheet degradation and module output or safety has been identified. However, such a relationship may be expected to become more pronounced with time, affecting system lifetime and ultimately the levelized cost of electricity (LCOE). Finally, the observed phenomena have implications for both backsheet product development and array design, especially for modules that utilize newer classes of non-fluoropolymer-based backsheets which are typically more susceptible to environmental degradation.« less

Differential degradation patterns of photovoltaic backsheets at the array level

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

Fairbrother, Andrew; Boyd, Matthew; Lyu, Yadong

There are relatively few field studies on the degradation of non-fluoropolymer-based backsheets, and understanding their in-field behavior is critical for further development of such products. In this paper, backsheet degradation of modules with one of these new types of backsheets (polyethylene naphthalate (PEN)-based) was documented at a four-year old utility-scale array located in Maryland (USA). Visual inspection, colorimetry, glossimetry, and Fourier-transform infrared spectroscopy (FTIR) revealed highly varied properties depending on module position within the array. Specifically, modules near the edge of the array and with higher mounting elevations underwent greater amounts of backsheet degradation, as indicated by yellowing and gloss-loss.more » The reason for these unique degradation patterns were differential backside exposure conditions, especially of ultraviolet light. This was strongly influenced by the array design, including array structural and environmental factors, such as module spacing and ground cover, respectively. Within the array, no clear link between backsheet degradation and module output or safety has been identified. However, such a relationship may be expected to become more pronounced with time, affecting system lifetime and ultimately the levelized cost of electricity (LCOE). Finally, the observed phenomena have implications for both backsheet product development and array design, especially for modules that utilize newer classes of non-fluoropolymer-based backsheets which are typically more susceptible to environmental degradation.« less

Determination of vitamin C in foods: current state of method validation.

PubMed

Spínola, Vítor; Llorent-Martínez, Eulogio J; Castilho, Paula C

2014-11-21

Vitamin C is one of the most important vitamins, so reliable information about its content in foodstuffs is a concern to both consumers and quality control agencies. However, the heterogeneity of food matrixes and the potential degradation of this vitamin during its analysis create enormous challenges. This review addresses the development and validation of high-performance liquid chromatography methods for vitamin C analysis in food commodities, during the period 2000-2014. The main characteristics of vitamin C are mentioned, along with the strategies adopted by most authors during sample preparation (freezing and acidification) to avoid vitamin oxidation. After that, the advantages and handicaps of different analytical methods are discussed. Finally, the main aspects concerning method validation for vitamin C analysis are critically discussed. Parameters such as selectivity, linearity, limit of quantification, and accuracy were studied by most authors. Recovery experiments during accuracy evaluation were in general satisfactory, with usual values between 81 and 109%. However, few methods considered vitamin C stability during the analytical process, and the study of the precision was not always clear or complete. Potential future improvements regarding proper method validation are indicated to conclude this review. Copyright © 2014. Published by Elsevier B.V.

Effects of Iris Surface Curvature on Iris Recognition

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

Thompson, Joseph T; Flynn, Patrick J; Bowyer, Kevin W

To focus on objects at various distances, the lens of the eye must change shape to adjust its refractive power. This change in lens shape causes a change in the shape of the iris surface which can be measured by examining the curvature of the iris. This work isolates the variable of iris curvature in the recognition process and shows that differences in iris curvature degrade matching ability. To our knowledge, no other work has examined the effects of varying iris curvature on matching ability. To examine this degradation, we conduct a matching experiment across pairs of images with varyingmore » degrees of iris curvature differences. The results show a statistically signi cant degradation in matching ability. Finally, the real world impact of these ndings is discussed« less

DEVELOPMENT OF METHOD 535 FOR THE DETERMINATION OF CHLOROACETANILIDE AND OTHER ACETAMIDE HERBICIDE DEGRADATES IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY

EPA Science Inventory

EPA Method 535 has been developed in order to provide a method for the analysis of "Alachlor ESA and other acetanilide degradation products" which are listed on U.S. EPA's 1998 Drinking Water Contaminant Candidate List. Method 535 uses solid phase extraction with a nonporous gr...

Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

PubMed

Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

2016-12-01

Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

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.

Two-Relaxation-Time Lattice Boltzmann Method for Advective-Diffusive-Reactive Transport

NASA Astrophysics Data System (ADS)

Yan, Z.; Hilpert, M.

2016-12-01

The lattice Boltzmann method (LBM) has been applied to study a wide range of reactive transport in porous and fractured media. The single-relaxation-time (SRT) LBM, employing single relaxation time, is the most popular LBM due to its simplicity of understanding and implementation. Nevertheless, the SRT LBM may suffer from numerical instability for small value of the relaxation time. By contrast, the multiple-relaxation-time (MRT) LBM, employing multiple relaxation times, can improve the numerical stability through tuning the multiple relaxation times, but the complexity of implementing this method restricts its applications. The two-relaxation-time (TRT) LBM, which employs two relaxation times, combines the advantages of SRT and MRT LBMs. The TRT LBM can produce simulations with better accuracy and stability than the SRT one, and is easier to implement than the MRT one. This work evaluated the numerical accuracy and stability of the TRT method by comparing the simulation results with analytical solutions of Gaussian hill transport and Taylor dispersion under different advective velocities. The accuracy generally increased with the tunable relaxation time τ, and the stability first increased and then decreased as τ increased, showing an optimal TRT method emerging the best numerical stability. The free selection of τ enabled the TRT LBM to simulate the Gaussian hill transport and Taylor dispersion under relatively high advective velocity, under which the SRT LBM suffered from numerical instability. Finally, the TRT method was applied to study the contaminant degradation by chemotactic microorganisms in porous media, which acted as a reprehensive of reactive transport in this study, and well predicted the evolution of microorganisms and degradation of contaminants for different transport scenarios. To sum up, the TRT LBM produced simulation results with good accuracy and stability for various advective-diffusive-reactive transport through tuning the relaxation time τ, illustrating its potential to study various biogeochemical behaviors in the subsurface environment.

Characterization of Infrastructure Materials using Nonlinear Ultrasonics

NASA Astrophysics Data System (ADS)

Liu, Minghe

In order to improve the safety, reliability, cost, and performance of civil and mechanical structures/components, it is necessary to develop techniques that are capable of characterizing and quantifying the amount of distributed damage in engineering materials before any detectable discontinuities (cracks, delaminations, voids, etc.) appear. In this dissertation, novel nonlinear ultrasonic NDE methods are developed and applied to characterize cumulative damage such as fatigue damage in metallic materials and degradation of cement-based materials due to chemical reactions. First, nonlinear Rayleigh surface waves are used to measure the near-surface residual stresses in shot-peened aluminum alloy (AA 7075) samples. Results show that the nonlinear Rayleigh wave is very sensitive to near-surface residual stresses, and has the potential to quantitatively detect them. Second, a novel two-wave mixing method is theoretically developed and numerically verified. This method is then successfully applied to detect the fatigue damage in aluminum alloy (AA 6061) samples subjected to monotonic compression. In addition to its high sensitivity to fatigue damage, this collinear wave mixing method allows the measurement over a specific region of interest in the specimen, and this capability makes it possible to obtain spatial distribution of fatigue damage through the thickness direction of the sample by simply timing the transducers. Third, the nonlinear wave mixing method is used to characterize the degradation of cement-based materials caused by alkali-silica reaction (ASR). It is found that the nonlinear ultrasonic method is sensitive to detect ASR damage at very early stage, and has the potential to identify the different damage stages. Finally, a micromechanics-based chemo-mechanical model is developed which relates the acoustic nonlinearity parameter to ASR damage. This model provides a way to quantitatively predict the changes in the acoustic nonlinearity parameter due to ASR damage, which can be used to guide experimental measurements for nondestructive evaluation of ASR damage.

An iterative shrinkage approach to total-variation image restoration.

PubMed

Michailovich, Oleg V

2011-05-01

The problem of restoration of digital images from their degraded measurements plays a central role in a multitude of practically important applications. A particularly challenging instance of this problem occurs in the case when the degradation phenomenon is modeled by an ill-conditioned operator. In such a situation, the presence of noise makes it impossible to recover a valuable approximation of the image of interest without using some a priori information about its properties. Such a priori information--commonly referred to as simply priors--is essential for image restoration, rendering it stable and robust to noise. Moreover, using the priors makes the recovered images exhibit some plausible features of their original counterpart. Particularly, if the original image is known to be a piecewise smooth function, one of the standard priors used in this case is defined by the Rudin-Osher-Fatemi model, which results in total variation (TV) based image restoration. The current arsenal of algorithms for TV-based image restoration is vast. In this present paper, a different approach to the solution of the problem is proposed based upon the method of iterative shrinkage (aka iterated thresholding). In the proposed method, the TV-based image restoration is performed through a recursive application of two simple procedures, viz. linear filtering and soft thresholding. Therefore, the method can be identified as belonging to the group of first-order algorithms which are efficient in dealing with images of relatively large sizes. Another valuable feature of the proposed method consists in its working directly with the TV functional, rather then with its smoothed versions. Moreover, the method provides a single solution for both isotropic and anisotropic definitions of the TV functional, thereby establishing a useful connection between the two formulae. Finally, a number of standard examples of image deblurring are demonstrated, in which the proposed method can provide restoration results of superior quality as compared to the case of sparse-wavelet deconvolution.

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

USGS Publications Warehouse

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

1997-01-01

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

Short stack modeling of degradation in solid oxide fuel cells. Part II. Sensitivity and interaction analysis

NASA Astrophysics Data System (ADS)

Gazzarri, J. I.; Kesler, O.

In the first part of this two-paper series, we presented a numerical model of the impedance behaviour of a solid oxide fuel cell (SOFC) aimed at simulating the change in the impedance spectrum induced by contact degradation at the interconnect-electrode, and at the electrode-electrolyte interfaces. The purpose of that investigation was to develop a non-invasive diagnostic technique to identify degradation modes in situ. In the present paper, we appraise the predictive capabilities of the proposed method in terms of its robustness to uncertainties in the input parameters, many of which are very difficult to measure independently. We applied this technique to the degradation modes simulated in Part I, in addition to anode sulfur poisoning. Electrode delamination showed the highest robustness to input parameter variations, followed by interconnect oxidation and interconnect detachment. The most sensitive degradation mode was sulfur poisoning, due to strong parameter interactions. In addition, we simulate several simultaneous two-degradation-mode scenarios, assessing the method's capabilities and limitations for the prediction of electrochemical behaviour of SOFC's undergoing multiple simultaneous degradation modes.

Complaints as starting point for vicious cycles in customer-employee-interactions.

PubMed

Traut-Mattausch, Eva; Wagner, Sara; Pollatos, Olga; Jonas, Eva

2015-01-01

A ring-model of vicious cycles in customer-employee-interaction is proposed: service employees perceive complaints as a threat to their self-esteem resulting in defense responses such as an increased need for cognitive closure, a devaluation of the customer and their information and degrading service behavior. Confronted with such degrading service behavior, customers react defensively as well, by devaluing the employee for example with regard to his/her competence and by reducing repurchase and positive word-of-mouth (WOM). Three studies investigated each link in this ring-model. In study 1, participants were confronted with an aggressive or neutral customer complaint. Results show that motivated closed-mindedness (one aspect of the need for cognitive closure) increases after an aggressive complaint leading to a devaluation of the customer and their information, and in turn to a degrading service reaction. In study 2, participants were confronted with a degrading or favorable service reaction. Results show that they devaluate the employees' competence after receiving a degrading service reaction and thus reduce their intention to repurchase. In study 3, we finally examined our predictions investigating real customer-employee-interactions: we analyzed data from an evaluation study in which mystery callers tested the service hotline of an airline. Results show that the employees' competence is devaluated after degrading behavior and thus reduces positive WOM.

Enhancing emerging organic compound degradation: applying chaotic flow to managed aquifer recharge

NASA Astrophysics Data System (ADS)

Rodríguez-Escales, Paula; Fernandez-Garcia, Daniel; Drechsel, Johannes; Folch, Albert; Sanchez-Vila, Xavier

2017-04-01

The coupling of Managed Aquifer Recharge with soil aquifer remediation treatment, by placing a reactive layer containing organic matter at the bottom of the infiltration pond, is a promising technology to improve the rate of degradation of EOCs. Its success is based on assuming that recharged water and groundwater get well mixed, which is not always true. It has been demonstrated that mixing can be enhanced by inducing chaotic advection through extraction-injection engineering. In this work we analyze how chaotic advection might enhance the spreading of redox conditions with the final aim of improving degradation of a mix of benzotriazoles: benzotriazole, 5-methyl-benzotriazole, and 5-chloro-benzotriazole. The first two compounds are better degraded under aerobic conditions whereas the third one under nitrate reducing conditions. We developed a reactive transport model that describes how a recharged water rich in organic matter mixes with groundwater, how this organic matter is oxidized by different electron acceptors, and how the benzotriazoles are degraded attending for the redox state. The model was tested in different scenarios of recharge, both in homogenous and in heterogenous media. It was found that chaotic flow increases the spreading of the plume of recharged water. Consequently, different redox conditions coexist at a given time within the area affected by recharge, facilitating the degradation of EOCs.

Degradation of oil products in a soil from a Russian Barents hot-spot during electrodialytic remediation.

PubMed

Pedersen, Kristine B; Lejon, Tore; Jensen, Pernille E; Ottosen, Lisbeth M

2016-01-01

A highly oil-polluted soil from Krasnoe in North-West Russia was used to investigate the degradation of organic pollutants during electrodialytic remediation. Removal efficiencies were up to 70 % for total hydrocarbons (THC) and up to 65 % for polyaromatic hydrocarbons (PAH). Relatively more of the lighter PAH compounds and THC fractions were degraded. A principal component analysis (PCA) revealed a difference in the distribution of PAH compounds after the remediation. The observed clustering of experiments in the PCA scores plot was assessed to be related to the stirring rate. Multivariate analysis of the experimental settings and final concentrations in the 12 experiments revealed that the stirring rate of the soil suspension was by far the most important parameter for the remediation for both THC and PAH. Light was the second most important variable for PAH and seems to influence degradation. The experimental variables current density and remediation time did not significantly influence the degradation of the organic pollutants. Despite current density not influencing the remediation, there is potential for degrading organic pollutants during electrodialytic removal of heavy metals, as long as a stirred set-up is applied. Depending on remediation objectives, further optimisation may be needed in order to develop efficient remediation strategies.

40 CFR 265.314 - Special requirements for bulk and containerized liquids.

Code of Federal Regulations, 2012 CFR

2012-07-01

... (iii) Mixtures of these non-bio-degrad-a-ble materials. (2) Tests for non-bio-degrad-a-ble sorbents. (i) The sorbent material is determined to be non-bio-degrad-a-ble under ASTM Method G21-70 (1984a...

40 CFR 265.314 - Special requirements for bulk and containerized liquids.

Code of Federal Regulations, 2013 CFR

2013-07-01

... (iii) Mixtures of these non-bio-degrad-a-ble materials. (2) Tests for non-bio-degrad-a-ble sorbents. (i) The sorbent material is determined to be non-bio-degrad-a-ble under ASTM Method G21-70 (1984a...

40 CFR 265.314 - Special requirements for bulk and containerized liquids.

Code of Federal Regulations, 2014 CFR

2014-07-01

... (iii) Mixtures of these non-bio-degrad-a-ble materials. (2) Tests for non-bio-degrad-a-ble sorbents. (i) The sorbent material is determined to be non-bio-degrad-a-ble under ASTM Method G21-70 (1984a...

40 CFR 265.314 - Special requirements for bulk and containerized liquids.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (iii) Mixtures of these non-bio-degrad-a-ble materials. (2) Tests for non-bio-degrad-a-ble sorbents. (i) The sorbent material is determined to be non-bio-degrad-a-ble under ASTM Method G21-70 (1984a...

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

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

van Tilborg, J.; Barber, S. K.; Benedetti, C.

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this paper, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam.more » An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Finally, optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.« less

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

DOE PAGES

van Tilborg, J.; Barber, S. K.; Benedetti, C.; ...

2018-03-13

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this paper, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam.more » An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Finally, optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.« less

BAG-6 is essential for selective elimination of defective proteasomal substrates

PubMed Central

Minami, Ryosuke; Hayakawa, Atsuko; Kagawa, Hiroki; Yanagi, Yuko; Yokosawa, Hideyoshi

2010-01-01

BAG-6/Scythe/BAT3 is a ubiquitin-like protein that was originally reported to be the product of a novel gene located within the human major histocompatibility complex, although the mechanisms of its function remain largely obscure. Here, we demonstrate the involvement of BAG-6 in the degradation of a CL1 model defective protein substrate in mammalian cells. We show that BAG-6 is essential for not only model substrate degradation but also the ubiquitin-mediated metabolism of newly synthesized defective polypeptides. Furthermore, our in vivo and in vitro analysis shows that BAG-6 interacts physically with puromycin-labeled nascent chain polypeptides and regulates their proteasome-mediated degradation. Finally, we show that knockdown of BAG-6 results in the suppressed presentation of MHC class I on the cell surface, a procedure known to be affected by the efficiency of metabolism of defective ribosomal products. Therefore, we propose that BAG-6 is necessary for ubiquitin-mediated degradation of newly synthesized defective polypeptides. PMID:20713601

Bio-drying of municipal solid waste with high water content by aeration procedures regulation and inoculation.

PubMed

Zhang, Dong-Qing; He, Pin-Jing; Jin, Tai-Feng; Shao, Li-Ming

2008-12-01

To improve the water content reduction of municipal solid waste with high water content, the operations of supplementing a hydrolytic stage prior to aerobic degradation and inoculating the bio-drying products were conducted. A 'bio-drying index' was used to evaluate the bio-drying performance. For the aerobic processes, the inoculation accelerated organics degradation, enhanced the lignocelluloses degradation rate by 10.4%, and lowered water content by 7.0%. For the combined hydrolytic-aerobic processes, the inoculum addition had almost no positive effect on the bio-drying efficiency, but it enhanced the lignocelluloses degradation rate by 9.6% and strengthened the acidogenesis in the hydrolytic stage. Compared with the aerobic processes, the combined processes had a higher bio-drying index (4.20 for non-inoculated and 3.67 for the inoculated trials). Moreover, the lowest final water content occurred in the combined process without inoculation (50.5% decreased from an initial 72.0%).

Hydroxylation and hydrolysis: two main metabolic ways of spiramycin I in anaerobic digestion.

PubMed

Zhu, Pei; Chen, Daijie; Liu, Wenbin; Zhang, Jianbin; Shao, Lei; Li, Ji-an; Chu, Ju

2014-02-01

The anaerobic degradation behaviors of five macrolides including spiramycin I, II, III, midecamycin and josamycin by sludge were investigated. Within 32days, 95% of spiramycin I, II or III was degraded, while the remove rate of midecamycin or josamycin was 75%. SPM I degradation was much higher in nutrition supplementation than that just in sludge. The degradation products and processes of spiramycin I were further characterized. Three molecules, designated P-1, P-2 and P-3 according to their order of occurrence, were obtained and purified. Structural determination was then performed by nuclear magnetic resonance and MS/MS spectra, and data indicated that hydroxylation and hydrolysis were main reactions during the anaerobic digestion of spiramycin I. P-1 is the intermediate of hydroxylation, and P-2 is the intermediate of hydrolysis. P-3 is the final product of the both reaction. This study revealed a hydroxylation and hydrolysis mechanism of macrolide in anaerobic digestion. Copyright © 2013 Elsevier Ltd. All rights reserved.

An approach of habitat degradation assessment for characterization on coastal habitat conservation tendency.

PubMed

Zhou, Xi-Yin; Lei, Kun; Meng, Wei

2017-09-01

Coastal zones are population and economy highly intensity regions all over the world, and coastal habitat supports the sustainable development of human society. The accurate assessment of coastal habitat degradation is the essential prerequisite for coastal zone protection. In this study, an integrated framework of coastal habitat degradation assessment including landuse classification, habitat classifying and zoning, evaluation criterion of coastal habitat degradation and coastal habitat degradation index has been established for better regional coastal habitat assessment. Through establishment of detailed three-class landuse classification, the fine landscape change is revealed, the evaluation criterion of coastal habitat degradation through internal comparison based on the results of habitat classifying and zoning could indicate the levels of habitat degradation and distinguish the intensity of human disturbances in different habitat subareas under the same habitat classification. Finally, the results of coastal habitat degradation assessment could be achieved through coastal habitat degradation index (CHI). A case study of the framework is carried out in the Circum-Bohai-Sea-Coast, China, and the main results show the following: (1) The accuracy of all land use classes are above 90%, which indicates a satisfactory accuracy for the classification map. (2) The Circum-Bohai-Sea-Coast is divided into 3 kinds of habitats and 5 subareas. (3) In the five subareas of the Circum-Bohai-Sea-Coast, the levels of coastal habitat degradation own significant difference. The whole Circum-Bohai-Sea-Coast generally is in a worse state according to area weighting of each habitat subarea. This assessment framework of coastal habitat degradation would characterize the landuse change trend, realize better coastal habitat degradation assessment, reveal the habitat conservation tendency and distinguish intensity of human disturbances. Furthermore, it would support for accurate coastal zone protection measures for the specific coastal area. Copyright © 2017 Elsevier B.V. All rights reserved.

Techniques to evaluate the importance of common cause degradation on reliability and safety of nuclear weapons.

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

Darby, John L.

2011-05-01

As the nuclear weapon stockpile ages, there is increased concern about common degradation ultimately leading to common cause failure of multiple weapons that could significantly impact reliability or safety. Current acceptable limits for the reliability and safety of a weapon are based on upper limits on the probability of failure of an individual item, assuming that failures among items are independent. We expanded the current acceptable limits to apply to situations with common cause failure. Then, we developed a simple screening process to quickly assess the importance of observed common degradation for both reliability and safety to determine if furthermore » action is necessary. The screening process conservatively assumes that common degradation is common cause failure. For a population with between 100 and 5000 items we applied the screening process and conclude the following. In general, for a reliability requirement specified in the Military Characteristics (MCs) for a specific weapon system, common degradation is of concern if more than 100(1-x)% of the weapons are susceptible to common degradation, where x is the required reliability expressed as a fraction. Common degradation is of concern for the safety of a weapon subsystem if more than 0.1% of the population is susceptible to common degradation. Common degradation is of concern for the safety of a weapon component or overall weapon system if two or more components/weapons in the population are susceptible to degradation. Finally, we developed a technique for detailed evaluation of common degradation leading to common cause failure for situations that are determined to be of concern using the screening process. The detailed evaluation requires that best estimates of common cause and independent failure probabilities be produced. Using these techniques, observed common degradation can be evaluated for effects on reliability and safety.« less

Probabilistic Modeling for Risk Assessment of California Ground Water Contamination by Pesticides

NASA Astrophysics Data System (ADS)

Clayton, M.; Troiano, J.; Spurlock, F.

2007-12-01

The California Department of Pesticide Regulation (DPR) is responsible for the registration of pesticides in California. DPR's Environmental Monitoring Branch evaluates the potential for pesticide active ingredients to move to ground water under legal agricultural use conditions. Previous evaluations were primarily based on threshold values for specific persistence and mobility properties of pesticides as prescribed in the California Pesticide Contamination Prevention Act of 1985. Two limitations identified with that process were the univariate nature where interactions of the properties were not accounted for, and the inability to accommodate multiple values of a physical-chemical property. We addressed these limitations by developing a probabilistic modeling method based on prediction of potential well water concentrations. A mechanistic pesticide transport model, LEACHM, is used to simulate sorption, degradation and transport of a candidate pesticide through the root zone. A second empirical model component then simulates pesticide degradation and transport through the vadose zone to a receiving ground water aquifer. Finally, degradation during transport in the aquifer to the well screen is included in calculating final potential well concentrations. Using Monte Carlo techniques, numerous LEACHM simulations are conducted using random samples of the organic carbon normalized soil adsorption coefficients (Koc) and soil dissipation half-life values derived from terrestrial field dissipation (TFD) studies. Koc and TFD values are obtained from gamma distributions fitted to pooled data from agricultural-use pesticides detected in California ground water: atrazine, simazine, diuron, bromacil, hexazinone, and norflurazon. The distribution of predicted well water concentrations for these pesticides is in good agreement with concentrations measured in domestic wells in coarse, leaching vulnerable soils of Fresno and Tulure Counties. The leaching potential of a new pesticide is evaluated by substituting it's sorption and persistence data into the model. Because such Koc and TFD data are often sparse, model inputs are typically derived from sampling of a fitted simple triangular distribution. A new product is considered to be a potential ground water contaminant if the 95th percentile of predicted well water concentrations is greater than 0.05 mg/L.