Sonolytic degradation of butyric acid in aqueous solutions.

PubMed

Dükkancı, Meral; Gündüz, Gönül

2013-11-15

The sonolytic degradation of butyric acid was investigated in an ultrasonic reactor emitting waves at 850 kHz. The effects of the ultrasonic power, the initial concentration of butyric acid, and the addition of H2O2 were studied on the degradation of butyric acid. In the sonication of butyric acid, degradation degrees as high as 31.5% could be achieved at a power of 31 W, at an initial concentration of 2.8 mM butyric acid with the addition of 0.34 M H2O2 for a sonication time of 5 h. The degradation of butyric acid increased with irradiation time, indicating first order kinetics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rapid degradation of phenol by ultrasound-dispersed nano-metallic particles (NMPs) in the presence of hydrogen peroxide: A possible mechanism for phenol degradation in water.

PubMed

Singh, Jiwan; Yang, Jae-Kyu; Chang, Yoon-Young

2016-06-15

The present study was carried out to investigate the degradation of phenol by ultrasonically dispersed nano-metallic particles (NMPs) in an aqueous solution of phenol. Leaching liquor from automobile shredder residue (ASR) was used to obtain the NMPs. The prepared NMPs were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and by X-ray diffraction (XRD). The SEM images show that the diameters of the NMPs were less than 50 nm. An SEM-EDX elemental analysis reveals that Fe was the most commonly found element (weight %) in the NMPs. The FTIR and XRD peaks indicate the presence of metals oxides on the surfaces of the NMPs. The results of the XPS analysis indicate that various elements (e.g., C, O, Zn, Cu, Mn, Fe) are present on the surfaces of the NMPs. The effects of the NMP dose, the initial solution pH, and of different concentrations of phenol and H2O2 on the phenol degradation characteristics were evaluated. The results of this study demonstrate that phenol degradation can be improved by increasing the amount of NMPs, whereas it is reduced with an increase in the phenol concentration. The degradation of phenol by ultrasonically dispersed NMPs followed the pseudo-first-order kinetics. The probable mechanism of phenol degradation by ultrasonically dispersed NMPs was the oxidation of phenol caused by the hydroxyl radicals produced during the reaction between H2O2 and the NMPs during the ultrasonication process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental design approach to the optimization of ultrasonic degradation of alachlor and enhancement of treated water biodegradability.

PubMed

Torres, Ricardo A; Mosteo, Rosa; Pétrier, Christian; Pulgarin, Cesar

2009-03-01

This work presents the application of experimental design for the ultrasonic degradation of alachlor which is pesticide classified as priority substance by the European Commission within the scope of the Water Framework Directive. The effect of electrical power (20-80W), pH (3-10) and substrate concentration (10-50mgL(-1)) was evaluated. For a confidential level of 90%, pH showed a low effect on the initial degradation rate of alachlor; whereas electrical power, pollutant concentration and the interaction of these two parameters were significant. A reduced model taking into account the significant variables and interactions between variables has shown a good correlation with the experimental results. Additional experiments conducted in natural and deionised water indicated that the alachlor degradation by ultrasound is practically unaffected by the presence of potential *OH radical scavengers: bicarbonate, sulphate, chloride and oxalic acid. In both cases, alachlor was readily eliminated ( approximately 75min). However, after 4h of treatment only 20% of the initial TOC was removed, showing that alachlor by-products are recalcitrant to the ultrasonic action. Biodegradability test (BOD5/COD) carried out during the course of the treatment indicated that the ultrasonic system noticeably increases the biodegradability of the initial solution.

Concomitant degradation of bisphenol A during ultrasonication and Fenton oxidation and production of biofertilizer from wastewater sludge.

PubMed

Mohapatra, D P; Brar, S K; Tyagi, R D; Surampalli, R Y

2011-09-01

Degradation of bisphenol A (BPA), an endocrine disruptor, from wastewater sludge (WWS) has attracted great interest recently. In the present study, the effects of different pre-treatment methods, including ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) was assessed in terms of increase in solubilization of WWS and simultaneous degradation of BPA. Among US, FO and FS pre-treatment, higher suspended solids (SS), volatile suspended solids (VSS), chemical oxygen demand (COD) and soluble organic carbon (SOC) solubilization (39.7%, 51.2%, 64.5% and 17.6%, respectively) was observed during a ferro-sonication pre-treatment process carried out for 180 min, resulting in higher degradation of BPA (82.7%). In addition, the effect of rheological parameters (viscosity and particle size) and zeta potential on the degradation of BPA in raw and different pre-treated sludges were also investigated. The results showed that a decrease in viscosity and particle size and an increase in zeta potential resulted in higher degradation of BPA. BPA degradation by laccases produced by Sinorhizobium meliloti in raw and pre-treated sludge was also determined. Higher activity of laccases (207.9 U L(-1)) was observed in ferro-sonicated pre-treated sludge (180 min ultrasonic time), resulting in higher removal of BPA (0.083 μg g(-1)), suggesting concomitant biological degradation of BPA. Copyright © 2011 Elsevier B.V. All rights reserved.

Analytical Ultrasonics in Materials Research and Testing

NASA Technical Reports Server (NTRS)

Vary, A.

1986-01-01

Research results in analytical ultrasonics for characterizing structural materials from metals and ceramics to composites are presented. General topics covered by the conference included: status and advances in analytical ultrasonics for characterizing material microstructures and mechanical properties; status and prospects for ultrasonic measurements of microdamage, degradation, and underlying morphological factors; status and problems in precision measurements of frequency-dependent velocity and attenuation for materials analysis; procedures and requirements for automated, digital signal acquisition, processing, analysis, and interpretation; incentives for analytical ultrasonics in materials research and materials processing, testing, and inspection; and examples of progress in ultrasonics for interrelating microstructure, mechanical properites, and dynamic response.

An Ultrasonic Technique to Determine the Residual Strength of Adhesive Bonds

NASA Technical Reports Server (NTRS)

Achenbach, J. D.; Tang, Z.

1999-01-01

In this work, ultrasonic techniques to nondestructively evaluate adhesive bond degradation have been studied. The key to the present approach is the introduction of an external factor which pulls the adhesive bond in the nonlinear range, simultaneously with the application of an ultrasonic technique. With the aid of an external static tensile loading, a superimposed longitudinal wave has.been used to obtain the slopes of the stress-strain curve of an adhesive bond at a series of load levels. The critical load, at which a reduction of the slope is detected by the superimposed longitudinal wave, is an indication of the onset of nonlinear behavior of the adhesive bond, and therefore of bond degradation. This approach has been applied to the detection of adhesive bond degradation induced by cyclic fatigue loading. Analogously to the longitudinal wave case, a superimposed shear wave has been used to obtain the effective shear modulus of adhesive layers at different shear load levels. The onset of the nonlinear behavior of an adhesive bond under shear loading has been detected by the use of a superimposed shear wave. Experiments show that a longitudinal wave can also detect the nonlinear behavior when an adhesive bond is subjected to shear loading. An optimal combination of ultrasonic testing and mechanical loading methods for the detection of degradation related nonlinear behavior of adhesive bonds has been discussed. For the purpose of a practical application, an ultrasonic technique that uses a temperature increase as an alternative to static loading has also been investigated. A general strain-temperature correspondence principle that relates a mechanical strain to a temperature has been presented. Explicit strain-temperature correspondence relations for both the tension and shear cases have been derived. An important parameter which quantifies the relation between the wave velocity and temperature has been defined. This parameter, which is indicative of adhesive bond nonlinearity and which can be conveniently obtained by an ultrasonic measurement, has been used as an indication of adhesive bond degradation. Experimental results have shown that the temperature increase method is a convenient and productive alternative to static loading. A technique which uses the reflected waveform data to obtain the fundamental ultrasonic parameters (transit time, reflection coefficient and attenuation coefficient) of an adhesive bond has also been presented.

The reclaiming of butyl rubber and in-situ compatibilization of thermoplastic elastomer by power ultrasound

NASA Astrophysics Data System (ADS)

Feng, Wenlai

This is a study of the continuous ultrasound aided extrusion process for the in-situ compatibilization of isotactic polypropylene (iPP)/ethylene-propylene diene rubber (EPDM) thermoplastic elastomer (TPE) using a newly developed ultrasonic treatment reactor. The rheological, mechanical properties and morphology of the TPE with and without ultrasonic treatment were studied. In-situ compatibilization in the ultrasonically treated blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM TPE. The ultrasonic treatments of butyl rubber gum and ultrasonic devulcanization of butyl rubber, tire-curing bladder during extrusion using a grooved barrel ultrasonic reactor were carried out. The ultrasonic treatment of gum caused degradation of the polymer main chain leading to lower molecular weight, broader molecular weight distribution, less unsaturation and changes in physical properties. The devulcanization of butyl rubber was successfully accomplished only at severe conditions of ultrasonic treatment. The mechanical properties of vulcanizates prepared from devulcanized butyl rubber are comparable to that of the virgin vulcanizate. The molecular characterization of sol fraction of devulcanized butyl rubber showed the devulcanization and degradation of butyl rubber occurred simultaneously. 1H NMR transverse relaxation was also used to study butyl rubber gum before and after ultrasonic treatment, and ultrasonically devulcanized unfilled butyl rubber. The T2 relaxation decays were successfully described using a two-component model. The recyclability of tire-curing bladder was also investigated. Gel fraction, crosslink density, cure behavior, dynamic properties and mechanical properties were measured. Good mechanical properties of revulcanized rubber were achieved by blending devulcanized rubber with the carbon black filled virgin butyl rubber. The structural characteristics of devulcanized butyl rubber were simulated using the Dobson-Gordon theory of rubber network statistics. A fairly good agreement between experimental data and theoretical prediction on normalized gel fraction vs. normalized crosslink density was achieved. The simulation of devulcanized butyl rubber indicated that the rate of crosslink rupture is much higher than that of the main chain.

Evaluation of Ultrasonic and Thermal Nondestructive Evaluation for the Characterization of Aging Degradation in Braided Composite Materials

NASA Technical Reports Server (NTRS)

Martin, Richard E.

2010-01-01

This paper examines the ability of traditional nondestructive evaluation (NDE) techniques to measure the degradation of braided polymer composite materials subjected to thermal-humidity cycling to simulate aging. A series of braided composite coupons were examined using immersion ultrasonic and pulsed thermography techniques in the as received condition. These same specimens were then examined following extended thermal-humidity cycling. Results of this examination did not show a significant change in the resulting (NDE) signals.

Detection of oxygen species generated by WO{sub 3} modification fullerene/TiO{sub 2} in the degradation of 1,5-diphenyl carbazide

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

Meng, Ze-Da; Department of Advanced Materials Science and Engineering, Hanseo University, Seosan-si, Chungnam-do 356-706; Zhu, Lei

2014-08-15

Highlights: • Reactive oxygen species were detected through oxidation reaction from DPCI to DPCO. • Generated reactive oxygen species and hydroxyl radicals can be analysed by DPCI degradation. • C{sub 60} have good effect in photo/ultrasonic degradation process. • Enhanced adsorption capacity can increase the degradation effect. • Photocatalytic activity attributed to photo-absorption effect by C{sub 60} and cooperative effect of WO{sub 3} and TiO{sub 2}. - Abstract: In the present work, powders with different relative mole ratios of WO{sub 3}-fullerene/TiO{sub 2} were irradiated by visible light and ultrasonic. The composite obtained was characterized by BET surface area measurements, X-raymore » diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and UV–vis analysis. A methylene blue (MB) solution under visible light and ultrasonic irradiation was used to determine the catalytic activity. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Finally, we performed experiments to find the optimum relative mole ratio of fullerene for the degradation of MB.« less

Sonochemical and photosonochemical degradation of 4-chlorophenol in aqueous media.

PubMed

Hamdaoui, Oualid; Naffrechoux, Emmanuel

2008-09-01

The degradation of 4-chlorophenol (4-CP) in aqueous media by 516 kHz ultrasonic irradiation was investigated in order to clarify the degradation mechanism. The degradation of concentrated 4-CP solution by means of ultrasound, UV irradiation and their combined application was also studied. The obtained results indicate that *OH radical are the primary reactive species responsible for 4-CP ultrasonic degradation. Very little 4-CP degradation occurs if the sonolysis is carried out in the presence of the *OH radical scavenger tert-butyl alcohol, also indicating that little or no pyrolysis of the compound occurs. The dominant degradation mechanism is the reaction of substrate with *OH radicals at the gas bubble-liquid interface rather than high temperature direct pyrolysis in ultrasonic cavities. This mechanism can explain the lower degradation rate of the ionic form of 4-CP that is partly due to the rapid dissociation of *OH radicals in alkaline solutions. The sonochemical destruction of concentrated 4-CP aqueous solution is obtained with low rate. Coupling photolysis with ultrasound irradiation results in increased efficiency compared to the individual processes operating at common conditions. Interestingly, the photosonochemical decomposition rate constant is greater than the additive rate constants of the two processes. This may be the result of three different oxidative processes direct photochemical action, high frequency sonochemistry and reaction with ozone produced by UV irradiation of air, dissolved in liquid phase because of the geyser effect of ultrasound streaming. Additionally, the photodecomposition, at 254 nm, of hydrogen peroxide produced by ultrasound generating *OH radical can partly explain the destruction enhancement.

Preparation and functional evaluation of antihypertensive polypeptides from rice based on ultrasonic pretreatment

USDA-ARS?s Scientific Manuscript database

Enzymolysis was used for preparation of antihypertensive peptide from rice. Following studies were conducted:ultrasonic pretreatment of substrate protein, ultrafilter of hydrolysate and test of anti-digestive enzyme degradation and one-time feeding of spontaneously hypertensive rats (SHR) of antihyp...

The effect of ultrasonic irradiation on the structure, morphology and photocatalytic performance of ZnO nanoparticles by sol-gel method.

PubMed

Mahdavi, Reza; Ashraf Talesh, S Siamak

2017-11-01

In this research, the effect of ultrasonic irradiation power (0, 75, 150 and 200W) and time (0, 5, 15 and 20min) on the structure, morphology and photocatalytic activity of zinc oxide nanoparticles synthesized by sol-gel method was investigated. Crystallographic structures and the morphologies of the resultant powders were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns showed that ZnO samples were crystallized in their pure phase. The purity of samples was increased by increasing the ultrasonic irradiation power and time. Not only did ultrasonic irradiation unify both the structure and the morphology, but also it reduced the size and prohibited particles from aggregation. The optical behavior of the samples was studied by UV-vis spectroscopy. Photocatalytic activity of particles was measured by degradation of methyl orange under radiation of ultraviolet light. Ultrasound nanoparticles represented higher degradation compared to non-ultrasound ones. Copyright © 2017 Elsevier B.V. All rights reserved.

Fate of pharmaceuticals in contaminated urban wastewater effluent under ultrasonic irradiation.

PubMed

Naddeo, V; Meriç, S; Kassinos, D; Belgiorno, V; Guida, M

2009-09-01

The application of sonolysis (US) for remediation of wastewater is an area of increasing interest. The aim of this study was to evaluate the ultrasonic (US) process on the degradation of pharmaceuticals (diclofenac (DCF), amoxicillin (AMX), carbamazepine (CBZ)) in single solutions and also in three mixtures spiked in urban wastewater effluent. Several operating conditions, such as power density (25-100 W L(-1)), initial substrate concentrations (2.5-10 mg L(-1)), initial solution pH (3-11), and air sparging were varied for the evaluation and understanding of the process. The degradation (as assessed by measuring UV absorbance), the generation of hydroxyl radicals (as assessed measuring H(2)O(2) concentration), the mineralization (in terms of TOC and COD removal), and the aerobic biodegradability (as assessed by the BOD(5)/COD ratio) were monitored during sonication. Ecotoxicity to Daphnia magna, Pseudokirchneriella subcapitata and Lepidium sativum before and after treatment was also evaluated. It was found that the pharmaceuticals conversion is enhanced at increased applied power densities, acidic conditions and in the presence of dissolved air. The reaction rate increases with increasing initial concentration of single pharmaceuticals but it remains constant in the mixtures, indicating different kinetic regimes (i.e. first and zero order respectively). Mineralization is a slow process as reaction by-products are more stable than pharmaceuticals to total oxidation; nonetheless, they are also more readily biodegradable. The toxicity of the wastewater samples before and after contamination with pharmaceuticals both in mixtures and in single substance-containing solutions was observed more severely on P. subcapitata; a fact that raises concerns in regards to the discharge of such effluents. D. magna displayed less sensitivity compared to P. subcapitata because it belongs in a lower taxonomic species than D. magna. The germination index of L. sativum in the presence of the drugs' mixture was stimulated instead of inducing any toxicity effect and this might be attributed to the fact the sample, laden with very low drug concentrations was able to act as a provider of additional nutrient elements.

Effect of aerosol particles generated by ultrasonic humidifiers on the lung in mouse.

PubMed

Umezawa, Masakazu; Sekita, Keisuke; Suzuki, Ken-Ichiro; Kubo-Irie, Miyoko; Niki, Rikio; Ihara, Tomomi; Sugamata, Masao; Takeda, Ken

2013-12-21

Ultrasonic humidifiers silently generate water droplets as a cool fog and produce most of the dissolved minerals in the fog in the form of an aerosolized "white dust." However, the health effect of these airborne particles is largely unknown. This study aimed to characterize the aerosol particles generated by ultrasonic humidifiers and to investigate their effect on the lung tissue of mice. An ultrasonic humidifier was operated with tap water, high-silica water, ultrapure water, or other water types. In a chamber (0.765 m3, ventilation ratio 11.5 m3/hr), male ICR mice (10-week-old) were exposed by inhalation to an aerosol-containing vapor generated by the humidifier. After exposure for 7 or 14 days, lung tissues and bronchoalveolar lavage fluid (BALF) were collected from each mouse and examined by microarray, quantitative reverse transcription-polymerase chain reaction, and light and electron microscopy. Particles generated from the humidifier operated with tap water had a mass concentration of 0.46 ± 0.03 mg/m3, number concentration of (5.0 ± 1.1) × 10(4)/cm3, and peak size distribution of 183 nm. The particles were phagocytosed by alveolar macrophages in the lung of mice. Inhalation of particles caused dysregulation of genes related to mitosis, cell adhesion molecules, MHC molecules and endocytosis, but did not induce any signs of inflammation or tissue injury in the lung. These results indicate that aerosol particles released from ultrasonic humidifiers operated with tap water initiated a cellular response but did not cause severe acute inflammation in pulmonary tissue. Additionally, high mineral content tap water is not recommended and de-mineralized water should be recommended in order to exclude any adverse effects.

Sono- and photocatalytic activities of SnO2 nanoparticles for degradation of cationic and anionic dyes

NASA Astrophysics Data System (ADS)

Paramarta, Valentinus; Taufik, Ardiansyah; Munisa, Lusitra; Saleh, Rosari

2017-01-01

The current research work focuses on the catalytic activity of SnO2 nanoparticles (NPs) against degradation of both cationic dye (methylene blue) and anionic dye (Congo-red). SnO2 NPs were synthesized under the sol-gel method and were characterized by performing X-ray diffraction, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) Brunauer-Emmet-Teller (BET) surface area analysis and UV-Vis spectroscopy. The results demonstrate that SnO2 NPs has well crystalline structure with the crystallite size of 44 nm. The degradation of dyes was studied under ambient temperature using ultrasonicator and UV light, respectively. The sono- and photocatalytic activities of SnO2 NPs on dyes were analyzed by measuring the change in absorbance of dyes under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the degradation in the concentration of the dyes before and after irradiation of ultrasonic and light, respectively. The influence of other parameters such as catalyst dosage, pH and scavenger have also been investigated. The catalytic activity is enhanced in the presence of ultrasonic irradiation. The degradation of both dyes follows pseudo-first order kinetics. The reusability tests have also been done to ensure the stability of the used catalysts. A reasonable mechanism of sono- and photocatalysis with SnO2 NPs has been proposed by correlating the active radical species involved with the physical properties of the as-synthesized samples.

Ultrasonic Welding of Graphite/Thermoplastic Composite

NASA Technical Reports Server (NTRS)

Hardy, S. S.; Page, D. B.

1982-01-01

Ultrasonic welding of graphite/thermoplastic composite materials eliminates need for fasteners (which require drilling or punching, add weight, and degrade stiffness) and can be totally automated in beam fabrication and assembly jigs. Feasibility of technique has been demonstrated in laboratory tests which show that neither angular orientation nor vacuum affect weld quality.

Synthesis of novel sonocatalyst Er3+:YAlO3/Nb2O5 and its application for sonocatalytic degradation of methamphetamine hydrochloride.

PubMed

Wei, Chunsheng; Yi, Kuiyu; Sun, Guangsheng; Wang, Jun

2018-04-01

The composited sonocatalyst Er 3+ :YAlO 3 /Nb 2 O 5 was prepared by ultrasonic dispersion and high temperature calcinations method. The microstructure of Er 3+ :YAlO 3 was prepared via sol-gel method and Nb 2 O 5 was prepared by hydrothermal method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), ultraviolet-visible (UV-vis) spectra and photoluminescence (PL) spectra, respectively. The sonocatalytic decomposition activity of composite sonocatalyst Er 3+ :YAlO 3 /Nb 2 O 5 was investigated by using ultrasound as sound source and methamphetamine hydrochloride as the target degradation product. The influences of composite sonocatalyst Er 3+ :YAlO 3 /Nb 2 O 5 with different ratios, calcination temperature, ultrasonic power, ultrasonic temperature and recycle times were investigated. The results showed that the sonocatalytic degradation rate was 82.17% after 5 h sonocatalytic decomposition under the condition of ultrasonic power of 700 W, frequency of 45 kHz and surrounding temperature of 30 °C. The sonocatalytic degradation ability of composite sonocatalyst for methamphetamine hydrochloride in aqueous solution was still good after recycled five times. The hydroxyl radicals (OH) and holes (h + ) are identified and hydroxyl radicals (OH) plays a major role during the oxidation process. The experimental results show that sonocatalytic is a new idea for the harmless treatment of amphetamine-type stimulants. Copyright © 2017 Elsevier B.V. All rights reserved.

Porosity estimation of aged mortar using a micromechanical model.

PubMed

Hernández, M G; Anaya, J J; Sanchez, T; Segura, I

2006-12-22

Degradation of concrete structures located in high humidity atmospheres or under flowing water is a very important problem. In this study, a method for ultrasonic non-destructive characterization in aged mortar is presented. The proposed method makes a prediction of the behaviour of aged mortar accomplished with a three phase micromechanical model using ultrasonic measurements. Aging mortar was accelerated by immersing the probes in ammonium nitrate solution. Both destructive and non-destructive characterization of mortar was performed. Destructive tests of porosity were performed using a vacuum saturation method and non-destructive characterization was carried out using ultrasonic velocities. Aging experiments show that mortar degradation not only involves a porosity increase, but also microstructural changes in the cement matrix. Experimental results show that the estimated porosity using the proposed non-destructive methodology had a comparable performance to classical destructive techniques.

Intensification of sonochemical degradation of ammonium perfluorooctanoate by persulfate oxidant.

PubMed

Hao, Feifei; Guo, Weilin; Wang, Anqi; Leng, Yanqiu; Li, Helian

2014-03-01

Ammonium perfluorooctanoate (APFO) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. The decomposition of APFO in aqueous solution with a combination of persulfate oxidant and ultrasonic irradiation was investigated. The effects of operating parameters, such as ultrasonic power, persulfate concentration, APFO concentration, and initial media pH on APFO degradation were discussed. In the absence of persulfate, 35.5% of initial APFO in 46.4 μmol/L solution under ultrasound irradiation, was decomposed rapidly after 120 min with the defluorination ratio reaching 6.73%. In contrast, when 10 mmol/L persulfate was used, 51.2% of initial APFO (46.4 μmol/L) was decomposed and the defluorination ratio reached 11.15% within 120 min reaction time. Enhancement of the decomposition of APFO can be explained by acceleration of substrate decarboxylation, induced by sulfate radical anions formed from the persulfate during ultrasonic irradiation. The SO4(-•)/APFO reactions at the bubble-water interface appear to be the primary pathway for the sonochemical degradation of the perfluorinated surfactants. Copyright © 2013 Elsevier B.V. All rights reserved.

Layer of organic pine forest soil on top of chlorophenol-contaminated mineral soil enhances contaminant degradation.

PubMed

Sinkkonen, Aki; Kauppi, Sari; Simpanen, Suvi; Rantalainen, Anna-Lea; Strömmer, Rauni; Romantschuk, Martin

2013-03-01

Chlorophenols, like many other synthetic compounds, are persistent problem in industrial areas. These compounds are easily degraded in certain natural environments where the top soil is organic. Some studies suggest that mineral soil contaminated with organic compounds is rapidly remediated if it is mixed with organic soil. We hypothesized that organic soil with a high degradation capacity even on top of the contaminated mineral soil enhances degradation of recalcitrant chlorophenols in the mineral soil below. We first compared chlorophenol degradation in different soils by spiking pristine and pentachlorophenol-contaminated soils with 2,4,6-trichlorophenol in 10-L buckets. In other experiments, we covered contaminated mineral soil with organic pine forest soil. We also monitored in situ degradation on an old sawmill site where mineral soil was either left intact or covered with organic pine forest soil. 2,4,6-Trichlorophenol was rapidly degraded in organic pine forest soil, but the degradation was slower in other soils. If a thin layer of the pine forest humus was added on top of mineral sawmill soil, the original chlorophenol concentrations (high, ca. 70 μg g(-1), or moderate, ca. 20 μg g(-1)) in sawmill soil decreased by >40 % in 24 days. No degradation was noticed if the mineral soil was kept bare or if the covering humus soil layer was sterilized beforehand. Our results suggest that covering mineral soil with an organic soil layer is an efficient way to remediate recalcitrant chlorophenol contamination in mineral soils. The results of the field experiment are promising.

Effects of clay minerals on diethyl phthalate degradation in Fenton reactions.

PubMed

Chen, Ning; Fang, Guodong; Zhou, Dongmei; Gao, Juan

2016-12-01

Phthalate esters are a group of plasticizers, which are commonly detected in China's soils and surface water. Fenton reactions are naturally occurring and widely applied in the degradation of contaminants. However, limited research was considered the effects of clay minerals on contaminants degradation with OH oxidation. In this study, batch experiments were conducted to investigate the degradation of diethyl phthalate (DEP) in Fenton reactions in the presence of clay minerals, and the effects of clay type, Fe content in clay structure. The results showed the clay adsorption inhibited total degradation of DEP, and Fe content in clay structure played an important role in DEP degradation, including in solution and adsorbed in clay minerals. Clay minerals with less Fe content (<3%) quenched OH radical, while nontronite with Fe content 19.2% improved OH radical generation and accelerated DEP degradation in solution. The degradation of clay-adsorbed DEP was much slower than DEP in solution. Six main products of DEP degradation were identified, including monoethyl phthalate, phthalate acid, hydroxyl diethyl phthalate, etc. This study implied that phthalate ester's degradation would be much slower in natural water than expected in the presence of clay minerals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultrasonic propagation properties of red oak

Treesearch

Donald E. Yuhas; Bruce G. Isaacson; Daniel L. Schmoldt; Eugene Wengert

1999-01-01

This work was motivated by the need to identify ultrasonic parameters that exhibit the greatest sensitivity to wood degradation as the result of bacterial infection; the so-called ?wetwood? condition. Wetwood infection creates microscopic changes to the wood structure, which then surface as checks and shake following drying. Slower drying schedules can often mitigate...

Enhancement of aerobic biodegradability potential of municipal waste activated sludge by ultrasonic aided bacterial disintegration.

PubMed

Kavitha, S; Jessin Brindha, G M; Sally Gloriana, A; Rajashankar, K; Yeom, Ick Tae; Rajesh Banu, J

2016-01-01

An investigation was performed to study the influence of ultrasonic aided bacterial disintegration on the aerobic degradability of sludge. In first phase of the study, effective floc disruption was achieved at an ultrasonic specific energy input of 2.45kJ/kg TS with 44.5mg/L of Extracellular Polymeric Substance (EPS) release including 0.035U/mL and 0.025U/mL protease and amylase activity respectively. In second phase, experimental outcomes revealed bacterial disintegration of floc disrupted-sludge showing a maximum solubilization of about 23% and was observed to be superior to bacterially disintegrated (11%) and control (6%), respectively. The result of aerobic biodegradability of ultrasonic aided bacterially pretreated sludge showed volatile solids (VS) degradation of about 40.2%. The kinetic study of aerobic biodegradability through non linear regression modelling reveals that floc disrupted sludge showed better biodegradability with decay constant of about 0.19d(-1) relatively higher than the control (0.14d(-1)) and bacterially disintegrated (0.17d(-1)) sludges. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhancement in Diffusion of Electrolyte through Membrane Using Ultrasonic Dialysis Equipment with Plane Membrane

NASA Astrophysics Data System (ADS)

Li, Hui; Ohdaira, Etsuzo; Ide, Masao

1995-05-01

Application of ultrasound to accelerate the dialysis separation of electrolytes through a membrane was studied with ultrasonic dialysis equipment. The experiments were conducted with cellophane membrane and KCl solution, CH3COONa solution, and a mixture of KCl and saponin solutions. It was found that the diffusion velocity of electrolyte through a membrane with ultrasonic irradiation is faster than that without ultrasonic irradiation, and it increases with acoustic pressure. It has become clear that the reasons for enhancement caused by ultrasound are increase in liquid particle velocity and diffusion coefficient due to ultrasonic vibration. It was confirmed that the permeability of the membrane was not degraded by ultrasound in the ranges of acoustic pressure and irradiation time in this study.

Ultrasonic degradation of acetaminophen and naproxen in the presence of single-walled carbon nanotubes.

PubMed

Im, Jong-Kwon; Heo, Jiyong; Boateng, Linkel K; Her, Namguk; Flora, Joseph R V; Yoon, Jaekyung; Zoh, Kyung-Duk; Yoon, Yeomin

2013-06-15

Ultrasonic (US) and single-walled carbon nanotube (SWNT)-catalyzed ultrasonic (US/SWNT) degradation of a pharmaceutical (PhAC) mixture of acetaminophen (AAP) and naproxen (NPX) used as analgesics was carried out in water. In the absence of SWNTs, maximum degradations of AAP and NPX occurred at a high frequency (1000 kHz) and under acidic conditions (pH 3) and different solution temperatures (25 °C at 28 kHz and 35 °C at 1000 kHz) during US reactions. Rapid degradation of PhACs occurred within 10 min at 28 kHz (44.5% for AAP; 90.3% for NPX) and 1000 kHz (39.2% for AAP; 74.8% for NPX) at a SWNT concentration of 45 mgL(-1) under US/SWNT process, compared with 28 kHz (5.2% for AAP; 10.6% for NPX) and 1000 kHz (29.1% for AAP; 46.2% for NPX) under US process. Degradation was associated with the dispersion of SWNTs; small particles acted as nuclei during US reactions, enhancing the H2O2 production yield. NPX removal was greater than AAP removal under all US-induced reaction and SWNT adsorption conditions, which is governed by the chemical properties of PhACs. Based on the results, the optimal treatment performance was observed at 28 kHz with 45 mgL(-1) SWNTs (US/SWNT) within 10 min. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous sound velocity and thickness measurement by the ultrasonic pitch-catch method for corrosion-layer-forming polymeric materials.

PubMed

Kusano, Masahiro; Takizawa, Shota; Sakai, Tetsuya; Arao, Yoshihiko; Kubouchi, Masatoshi

2018-01-01

Since thermosetting resins have excellent resistance to chemicals, fiber reinforced plastics composed of such resins and reinforcement fibers are widely used as construction materials for equipment in chemical plants. Such equipment is usually used for several decades under severe corrosive conditions so that failure due to degradation may result. One of the degradation behaviors in thermosetting resins under chemical solutions is "corrosion-layer-forming" degradation. In this type of degradation, surface resins in contact with a solution corrode, and some of them remain asa corrosion layer on the pristine part. It is difficult to precisely measure the thickness of the pristine part of such degradation type materials by conventional pulse-echo ultrasonic testing, because the sound velocity depends on the degree of corrosion of the polymeric material. In addition, the ultrasonic reflection interface between the pristine part and the corrosion layer is obscure. Thus, we propose a pitch-catch method using a pair of normal and angle probes to measure four parameters: the thicknesses of the pristine part and the corrosion layer, and their respective sound velocities. The validity of the proposed method was confirmed by measuring a two-layer sample and a sample including corroded parts. The results demonstrate that the pitch-catch method can successfully measure the four parameters and evaluate the residual thickness of the pristine part in the corrosion-layer-forming sample. Copyright © 2017 Elsevier B.V. All rights reserved.

Intensification of abamectin pesticide degradation using the combination of ultrasonic cavitation and visible-light driven photocatalytic process: Synergistic effect and optimization study.

PubMed

Mosleh, Soleiman; Rahimi, Mahmood Reza

2017-03-01

Degradation of abamectin pesticide was carried out using visible light driven Cu 2 (OH)PO 4 -HKUST-1 MOF photocatalyst through the sonophotocatalytic technique. Cu 2 (OH)PO 4 -HKUST-1 MOF as a visible-light driven photocatalyst, was synthesized and characterized by XRD, SEM, EDS and DRS. The direct bang gaps of HKUST-1 MOF and Cu 2 (OH)PO 4 -HKUST-1 MOF were estimated about 2.63 and 2.59eV, respectively, which reveals that these photocatalysts can be activated under blue light illumination. All sonophotodegradation experiments were performed using a continuous flow-loop reactor. The central composite design (CCD) methodology was applied for modeling, optimization and investigation of influence of operational parameters, i.e. irradiation time, pH, solution flow rate, oxygen flow rate, initial concentration and photocatalyst dosage on the sonophotocatalytic degradation of abamectin. The maximum degradation efficiency of 99.93% was found at optimal values as 20min, 4, 90mL/min, 0.2mL/min, 30mg/L and 0.4g/L, for irradiation time, pH, solution flow rate, oxygen flow rate, initial concentration and photocatalyst dosage, respectively. Evaluation of the synergism in the combination of ultrasonic and photocatalysis lead to a synergistic index of 2.19, which reveals that coupling of ultrasonic and photocatalysis has a greater efficiency than the sum of individual procedures for degradation of abamectin. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradation Effect of Sulfa Antibiotics by Potassium Ferrate Combined with Ultrasound (Fe(VI)-US)

PubMed Central

Zhang, Kejia; Luo, Zhang; Zhang, Tuqiao; Gao, Naiyun; Ma, Yan

2015-01-01

Sulfa antibiotics are a family of typical broad-spectrum antibiotics, which have become one of the most frequently detected antibiotics in water, posing a great threat to human health and ecosystem. Potassium ferrate is a new type of high-efficiency multifunctional water treatment agent, collecting the effects of oxidation, adsorption, flocculation, coagulation, sterilization, and deodorization. Performance and mechanism of degradation of typical broad-spectrum antibiotics by Fe(VI)-US were further studied, investigating the degradation effect of sulfa antibiotics by single ultrasound, single potassium ferrate, and potassium ferrate-ultrasound (Fe(VI)-US). It was found that Fe(VI)-US technology had a significant role in promoting the degradation of sulfa antibiotics via orthogonal experiments. Factors evaluated included sulfa antibiotics type, pH value, potassium ferrate dosage, ultrasonic frequency, and ultrasonic power, with the pH value and potassium ferrate dosage being affected most significantly. One reason for synergy facilitating the degradation is the common oxidation of potassium ferrate and ultrasound, and the other is that Fe(III) produced promotes the degradation rate. According to the product analysis and degradation pathways of three sulfa antibiotics, ferrate-sonication sulfa antibiotics are removed by hydroxyl radical oxidation. PMID:26347876

Degradation Effect of Sulfa Antibiotics by Potassium Ferrate Combined with Ultrasound (Fe(VI)-US).

PubMed

Zhang, Kejia; Luo, Zhang; Zhang, Tuqiao; Gao, Naiyun; Ma, Yan

2015-01-01

Sulfa antibiotics are a family of typical broad-spectrum antibiotics, which have become one of the most frequently detected antibiotics in water, posing a great threat to human health and ecosystem. Potassium ferrate is a new type of high-efficiency multifunctional water treatment agent, collecting the effects of oxidation, adsorption, flocculation, coagulation, sterilization, and deodorization. Performance and mechanism of degradation of typical broad-spectrum antibiotics by Fe(VI)-US were further studied, investigating the degradation effect of sulfa antibiotics by single ultrasound, single potassium ferrate, and potassium ferrate-ultrasound (Fe(VI)-US). It was found that Fe(VI)-US technology had a significant role in promoting the degradation of sulfa antibiotics via orthogonal experiments. Factors evaluated included sulfa antibiotics type, pH value, potassium ferrate dosage, ultrasonic frequency, and ultrasonic power, with the pH value and potassium ferrate dosage being affected most significantly. One reason for synergy facilitating the degradation is the common oxidation of potassium ferrate and ultrasound, and the other is that Fe(III) produced promotes the degradation rate. According to the product analysis and degradation pathways of three sulfa antibiotics, ferrate-sonication sulfa antibiotics are removed by hydroxyl radical oxidation.

Ultrasonic inspection and analysis techniques in green and dried lumber

Treesearch

Mark E. Schafer; Robert J. Ross; Brian K. Brashaw; Roy D. Adams

1999-01-01

Ultrasonic inspection of lumber has been under investigation for over 20 years, with little commercial impact. Recently, the USDA Forest Products Laboratory (FPL) developed ultrasound-based scanning technology to examine both green and dried lumber. In green lumber, the bacterial infection called wetwood (a significant source of degradation in oak at the kiln-drying...

Influence of microarchitecture alterations on ultrasonic backscattering in an experimental simulation of bovine cancellous bone aging.

PubMed

Apostolopoulos, K N; Deligianni, D D

2008-02-01

An experimental model which can simulate physical changes that occur during aging was developed in order to evaluate the effects of change of mineral content and microstructure on ultrasonic properties of bovine cancellous bone. Timed immersion in hydrochloric acid was used to selectively alter the mineral content. Scanning electron microscopy and histological staining of the acid-treated trabeculae demonstrated a heterogeneous structure consisting of a mineralized core and a demineralized layer. The presence of organic matrix contributed very little to normalized broadband ultrasound attenuation (nBUA) and speed of sound. All three ultrasonic parameters, speed of sound, nBUA and backscatter coefficient, were sensitive to changes in apparent density of bovine cancellous bone. A two-component model utilizing a combination of two autocorrelation functions (a densely populated model and a spherical distribution) was used to approximate the backscatter coefficient. The predicted attenuation due to scattering constituted a significant part of the measured total attenuation (due to both scattering and absorption mechanisms) for bovine cancellous bone. Linear regression, performed between trabecular thickness values and estimated from the model correlation lengths, showed significant linear correlation, with R(2)=0.81 before and R(2)=0.80 after demineralization. The accuracy of estimation was found to increase with trabecular thickness.

Influence of ultrasound on the heterogeneous Fenton-like oxidation of acetic acid.

PubMed

Cihanoğlu, Aydın; Gündüz, Gönül; Dükkancı, Meral

2017-11-01

The main objective of this study is to investigate the effect of ultrasound on the heterogeneous Fenton-like oxidation of acetic acid, which is one of the most resistant carboxylic acids to oxidation. For this purpose, firstly, the degradation of acetic acid was examined by using ultrasound alone and the effects of different parameters such as: type of sonication system, ultrasonic power, and addition of H 2 O 2 were investigated on the degradation of acetic acid. There was no chemical oxygen demand (COD) reduction in the presence of sonication alone. In the presence of the heterogeneous Fenton-like oxidation process alone, at 303 K, COD reduction reached only 7.1% after 2 h of reaction. However, the combination of the heterogeneous Fenton-like oxidation process with ultrasound increased the COD reduction from 7.1% to 25.5% after 2 h of reaction in an ultrasonic bath operated at 40 kHz, while the COD reduction only increased from 7.1% to 8.9% in the ultrasonic reactor operated at 850 kHz. This result indicates that the hybrid process of ultrasound and heterogeneous Fenton-like oxidation is a promising process to degrade acetic acid.

Preparation of Er3+:Y3Al5O12/WO3-KNbO3 composite and application in treatment of methamphetamine under ultrasonic irradiation.

PubMed

Zhang, Hongbo; Huang, Yingying; Li, Guanshu; Wang, Guowei; Fang, Dawei; Song, Youtao; Wang, Jun

2017-03-01

Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder as an effective sonocatalyst was prepared via collosol-gelling-hydrothermal and high-temperature calcination methods. The textures of materials were observed by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In order to estimate the sonocatalytic activity of Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder, the sonocatalytic degradation of methamphetamine (MAPA) was performed. Furthermore, the influences of mass ratio of WO 3 and KNbO 3 , ultrasonic irradiation time, catalyst addition amount, initial methamphetamine (MAPA) concentration and used times on the sonocatalytic degradation of methamphetamine (MAPA) caused by Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 composite powder were investigated by using gas chromatography. Under optimal conditions of 1.00g/L Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 addition amount and 10.00mg/L methamphetamine (MAPA) initial concentration, 68% of methamphetamine (MAPA) could be removed after 150min ultrasonic irradiation. The experimental results showed that the Er 3+ :Y 3 Al 5 O 12 /WO 3 -KNbO 3 as sonocatalyst displayed an excellent sonocatalytic activity in degradation of methamphetamine (MAPA) under ultrasonic irradiation. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasonic nondestructive evaluation of impact-damaged graphite fiber composite

NASA Technical Reports Server (NTRS)

Williams, J. H., Jr.; Lampert, N. R.

1980-01-01

Unidirectional Hercules AS/3501-6 graphite fiber epoxy composites were subjected to repeated controlled low-velocity drop weight impacts in the laminate direction. The degradation was ultrasonically monitored using through-thickness attenuation and a modified stress wave factor (SWF). There appears to be strong correlations between the number of drop-weight impacts, the residual tensile strength, the through-thickness attenuation, and the SWF. The results are very encouraging with respect to the NDE potential of both of these ultrasonic parameters to provide strength characterizations in virgin as well as impact-damaged fiber composite structures.

Improved near-field characteristics of phased arrays for assessing concrete and cementitious materials

NASA Astrophysics Data System (ADS)

Wooh, Shi-Chang; Azar, Lawrence

1999-01-01

The degradation of civil infrastructure has placed a focus on effective nondestructive evaluation techniques to correctly assess the condition of existing concrete structures. Conventional high frequency ultrasonic response are severely affected by scattering and material attenuation, resulting in weak and confusing signal returns. Therefore, low frequency ultrasonic transducers, which avoid this problem of wave attenuation, are commonly used for concrete with limited capabilities. The focus of this research is to ascertain some benefits and limitations of a low frequency ultrasonic phased array transducer. In this paper, we investigate a novel low-frequency ultrasonic phased array and the results of experimental feasibility test for practical condition assessment of concrete structures are reported.

Acousto-Ultrasonic analysis of failure in ceramic matrix composite tensile specimens

NASA Technical Reports Server (NTRS)

Kautz, Harold E.; Chulya, Abhisak

1993-01-01

Three types of acousto-ultrasonic (AU) measurements, stress-wave factor (SWF), lowest antisymmetric plate mode group velocity (VS), and lowest symmetric plate mode group velocity (VL), were performed on specimens before and after tensile failure. Three different Nicalon fiber architectures with ceramic matrices were tested. These composites were categorized as 1D (unidirectional fiber orientation) SiC/CAS glass ceramic, and 2D and 3D woven SiC/SiC ceramic matrix materials. SWF was found to be degraded after tensile failure in all three material categories. VS was found to be degraded only in the 1D SiC/CAS. VL was difficult to determine on the irregular specimen surfaces but appeared unchanged on all failed specimens. 3D woven specimens with heat-treatment at high temperature exhibited degradation only in SWF.

Effect of ultrasonication on anaerobic degradability of solid waste digestate.

PubMed

Boni, M R; D'Amato, E; Polettini, A; Pomi, R; Rossi, A

2016-02-01

This paper evaluates the effect of ultrasonication on anaerobic biodegradability of lignocellulosic residues. While ultrasonication has been commonly applied as a pre-treatment of the feed substrate, in the present study a non-conventional process configuration based on recirculation of sonicated digestate to the biological reactor was evaluated at the lab-scale. Sonication tests were carried out at different applied energies ranging between 500 and 50,000kJ/kg TS. Batch anaerobic digestion tests were performed on samples prepared by mixing sonicated and untreated substrate at two different ratios (25:75 and 75:25 w/w). The results showed that when applied as a post-treatment of digestate, ultrasonication can positively affect the yield of anaerobic digestion, mainly due to the dissolution effect of complex organic molecules that have not been hydrolyzed by biological degradation. A good correlation was found between the CH4 production yield and the amount of soluble organic matter at the start of digestion tests. The maximum gain in biogas production was 30% compared to that attained with the unsonicated substrate, which was tentatively related to the type and concentration of the metabolic products. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sequential low and medium frequency ultrasound assists biodegradation of wheat chaff by white rot fungal enzymes.

PubMed

Oliver, Christine M; Mawson, Raymond; Melton, Laurence D; Dumsday, Geoff; Welch, Jessica; Sanguansri, Peerasak; Singh, Tanoj K; Augustin, Mary Ann

2014-10-13

The consequences of ultrasonic pre-treatment using low (40 kHz) and medium (270 kHz) frequency (40 kHz followed by 270 kHz) on the degradation of wheat chaff (8 g 100ml(-1) acetate buffer, pH 5) were evaluated. In addition, the effects of the ultrasonic pre-treatment on the degradation of the wheat chaff when subsequently exposed to enzyme extracts from two white rot fungi (Phanerochaete chrysosporium and Trametes sp.) were investigated. Pre-treatment by sequential low and medium frequency ultrasound had a disruptive effect on the lignocellulosic matrix. Analysis of the phenolic-derived volatiles after enzymatic hydrolysis showed that biodegradation with the enzyme extract obtained from P. chrysosporium was more pronounced compared to that of the Trametes sp. The efficacy of the ultrasonic pre-treatment was attributed to increased enzyme accessibility of the cellulose fibrils due to sonication-induced disruption of the plant surface structure, as shown by changes in the microstructure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Non-Contact Evaluation for Articular Cartilage Using Ultrasound

NASA Astrophysics Data System (ADS)

Mori, Koji; Nakagawa, Yasuaki; Kuroki, Hiroshi; Nakashima, Keisuke; Ikeuchi, Ken; Mine, Takatomo; Nakamura, Takashi; Kawai, Shinya; Saito, Takashi

In orthopedic field, various new treatments of articular cartilage defect, for example autogenous osteochondral grafts, have been developed. With the spread of these treatments, orthopedists began to focus on the mechanical properties of recovered articular cartilage. The quantitative evaluation of articular cartilage before and after these treatments gives orthopedists the important information to improve these treatments and develop new treatments. We have been investigating the non-contact ultrasonic evaluation for articular cartilage under arthroscopy. In this paper, it was hypothesized that the ultrasonic evaluation depended on the collagen fiber in cartilage. The enzymatically degradation of collagen fiber in cartilage surface was performed. The effect of the degradation on sound velocity, attenuation coefficient and signal intensity, which is the index of cartilage stiffness calculated from the proposed method, was measured. The numerical analysis was performed to clear the relation between the cartilage character and ultrasonic parameters. Experimental and numerical results suggest that the present method can be expanded the sensitive evaluation for cartilage disease in clinical field.

Ethanol production from lignocellulose

DOEpatents

Ingram, Lonnie O.; Wood, Brent E.

2001-01-01

This invention presents a method of improving enzymatic degradation of lignocellulose, as in the production of ethanol from lignocellulosic material, through the use of ultrasonic treatment. The invention shows that ultrasonic treatment reduces cellulase requirements by 1/3 to 1/2. With the cost of enzymes being a major problem in the cost-effective production of ethanol from lignocellulosic material, this invention presents a significant improvement over presently available methods.

Dissolution and reconstitution of casein micelle containing dairy powders by high shear using ultrasonic and physical methods.

PubMed

Chandrapala, Jayani; Martin, Gregory J O; Kentish, Sandra E; Ashokkumar, Muthupandian

2014-09-01

The effect of shear on the solubilization of a range of dairy powders was investigated. The rate of solubilization of low solubility milk protein concentrate and micellar casein powders was examined during ultrasonication, high pressure homogenization and high-shear rotor-stator mixing and compared to low-shear overhead stirring. The high shear techniques were able to greatly accelerate the solubilization of these powders by physically breaking apart the powder agglomerates and accelerating the release of individual casein micelles into solution. This was achieved without affecting the structure of the solubilized proteins. The effect of high shear on the re-establishment of the mineral balance between the casein micelles and the serum was examined by monitoring the pH of the reconstituted skim milk powder after prior exposure to ultrasonication. Only minor differences in the re-equilibration of the pH were observed after sonication for up to 3 min, suggesting that the localized high shear forces exerted by sonication did not significantly affect the mass transfer of minerals from within the casein micelles. Copyright © 2014 Elsevier B.V. All rights reserved.

Study of the Earth's interior using measurements of sound velocities in minerals by ultrasonic interferometry

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

Li, Baosheng; Liebermann, Robert C.

2014-07-29

This paper reviews the progress of the technology of ultrasonic interferometry from the early 1950s to the present day. During this period of more than 60 years, sound wave velocity measurements have been increased from at pressures less than 1 GPa and temperatures less than 800 K to conditions above 25 GPa and temperatures of 1800 K. This is complimentary to other direct methods to measure sound velocities (such as Brillouin and impulsive stimulated scattering) as well as indirect methods (e.g., resonance ultrasound spectroscopy, static or shock compression, inelastic X-ray scattering). Newly-developed pressure calibration methods and data analysis procedures usingmore » a finite strain approach are described and applied to data for the major mantle minerals. The implications for the composition of the Earth’s mantle are discussed. The state-of-the-art ultrasonic experiments performed in conjunction with synchrotron X-radiation can provide simultaneous measurements of the elastic bulk and shear moduli and their pressure and temperature derivatives with direct determination of pressure. The current status and outlook/challenges for future experiments are summarized.« less

Sono-activated persulfate oxidation of diclofenac: Degradation, kinetics, pathway and contribution of the different radicals involved.

PubMed

Monteagudo, J M; El-Taliawy, H; Durán, A; Caro, G; Bester, K

2018-06-20

Degradation of a diclofenac aqueous solution was performed using persulfate anions activated by ultrasound. The objective of this study was to analyze different parameters affecting the diclofenac (DCF) removal reaction by the ultrasonic persulfate (US/PS) process and to evaluate the role played by various intermediate oxidative species such as hydroxyl- and sulfate radicals, superoxide radical anion or singlet oxygen in the removal process as well as to determine a possible reaction pathway. The effects of pH, initial persulfate anion concentration, ultrasonic amplitude and temperature on DCF degradation were examined. Sulfate and hydroxyl radicals were involved in the main reaction pathway of diclofenac. Diclofenac amide and three hydroxy-diclofenac isomers (3´-hydroxy diclofenac, 4´-hydroxy diclofenac and 5-hydroxy diclofenac) were identified as reaction intermediates. Copyright © 2018 Elsevier B.V. All rights reserved.

Photocatalytic degradation of diethyl phthalate using TiO{sub 2} nanoparticles

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

Singla, Pooja, E-mail: pooja.singla@thapar.edu; Pandey, O. P., E-mail: pooja.singla@thapar.edu; Singh, K., E-mail: pooja.singla@thapar.edu

2014-04-24

TiO{sub 2} nanoparticles predominantly in rutile phase are synthesized by ultrasonication assisted sol-gel method. TiO{sub 2} powder is characterized using X-ray powder diffraction and UV-vis diffuse reflectance. TiO{sub 2} is used as catalyst in photocatalytic degradation of Diethyl Phthalate. TiO{sub 2} exhibits good photocatalytic activity for the degradation of diethyl phthalate.

Review of Abiotic Degradation of Chlorinated Solvents by Reactive Iron Minerals

EPA Science Inventory

Abiotic degradation of chlorinated solvents by reactive iron minerals such as iron sulfides, magnetite, green rust, and other Fe(II)-containing minerals has been observed in both laboratory and field conditions. These reactive iron minerals typically form under iron and sulfate ...

Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation.

PubMed

Wang, Jun; Jiang, Zhe; Zhang, Liqun; Kang, Pingli; Xie, Yingpeng; Lv, Yanhui; Xu, Rui; Zhang, Xiangdong

2009-02-01

Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

Sonochemical degradation of perfluorooctanesulfonate in aqueous film-forming foams.

PubMed

Vecitis, Chad D; Wang, Yajuan; Cheng, Jie; Park, Hyunwoong; Mader, Brian T; Hoffmann, Michael R

2010-01-01

Aqueous film-forming foams (AFFFs) are fire extinguishing agents developed by the Navy to quickly and effectively combat fires occurring close to explosive materials and are utilized today at car races, airports, oil refineries, and military locations. Fluorochemical (FC) surfactants represent 1-5% of the AFFF composition, which impart properties such as high spreadability, negligible fuel diffusion, and thermal stability to the foam. FC's are oxidatively recalcitrant, persistent in the environment, and have been detected in groundwater at AFFF training sites. Ultrasonic irradiation of aqueous FCs has been reported to degrade and subsequently mineralize the FC surfactants perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS). Here we present results of the sonochemical degradation of aqueous dilutions of FC-600, a mixture of hydrocarbon (HC) and fluorochemical components including cosolvents, anionic hydrocarbon surfactants, fluorinated amphiphilic surfactants, anionic fluorinated surfactants, and thickeners such as starch. The primary FC surfactant in FC-600, PFOS, was sonolytically degraded over a range of FC-600 aqueous dilutions, 65 ppb < [PFOS]i < 13100 ppb. Sonochemical PFOS-AFFF decomposition rates, RAFFF-PFOS, are similar to PFOS-Milli-Q rates, RMQ-PFOS, indicating that the AFFF matrix only had a minor effect on the sonochemical degradation rate, 0.5 < RAFFF-PFOS/RMQ-PFOS < 2.0, even though the total organic concentration was 50 times the PFOS concentration, [Org]tot/[PFOS] 50, consistent with the superior FC surfactant properties. Sonochemical sulfate production is quantitative, delta[SO42-]/delta[PFOS] > or = 1, indicating that bubble-water interfacial pyrolytic cleavage of the C-S bond in PFOS is the initial degradation step, in agreement with previous studies done in Milli-Q water. Sonochemical fluoride production is significantly below quantitative expectations, delta[F-]/delta[PFOS] 4 vs 17, suggesting that in the AFFF matrix, PFOS' fluorochemical tail is not completely degraded, whereas Milli-Q studies yielded quantitative F- production. Measurements of time-dependent methylene blue active substances and total organic carbon indicate that the other FC-600 components were also sonolytically decomposed.

Investigation of polymeric scaffold degradation for drug delivery and neovascularization applications

NASA Astrophysics Data System (ADS)

Bulusu, Kartik V.; Alibouzar, Mitra; Castro, Nathan J.; Zhang, Lijie G.; Sarkar, Kausik; Plesniak, Michael W.

2016-11-01

Degradable polymer-based prosthetics for the treatment of osseous tissue defects, maxillo-/cranio-facial trauma and brain injury face two common clinical obstacles impeding efficient tissue engraftment i.e., controlled material release and neovascularization. Ascertaining the time scales of polymer degradation for controlled delivery of drugs and nutrients is critical to treatment efficacy and strategy. We incorporated multiple experimental methodologies to understand the driving forces of transport mechanisms in polyvinyl alcohol-based (PVA) 3D-printed scaffolds of different porosity. Scaffold degradation was monitored various pulsatile flow conditions using MEMS-based pressure catheters and an ultrasonic flow rate sensor. Ultrasonic properties (bulk attenuation and sound velocity) were measured to monitor the degradation process in a static, alkaline medium. Viscosity and the absorption spectra variations with PVA-solute concentrations were measured using a rheometer and a spectrophotometer, respectively. A simple mathematical model based on Fick's law of diffusion provides the fundamental description of solute transport from the scaffold matrices. However, macroscopic material release could become anomalous or non-Fickian in complex polymeric scaffold matrices. Supported by the GW Center for Biomimetics and Bioinspired Engineering and NIH Director's New Innovator Award 1DP2EB020549-01.

Combined ultrasound with Fenton treatment for the degradation of carcinogenic polycyclic aromatic hydrocarbons in textile dying sludge.

PubMed

Zhang, Jian-Hao; Zou, Hai-Yuan; Ning, Xun-An; Lin, Mei-Qing; Chen, Chang-Min; An, Tai-Cheng; Sun, Jian

2017-03-22

To develop an effective method to remove the toxic and carcinogenic polycyclic aromatic hydrocarbons (CPAHs) from textile dyeing sludge, five CPAHs were selected to investigate the degradation efficiencies using ultrasound combined with Fenton process (US/Fenton). The results showed that the synergistic effect of the US/Fenton process on the degradation of CPAHs in textile dyeing sludge was significant with the synergy degree of 30.4. During the US/Fenton process, low ultrasonic density showed significant advantage in degrading the CPAHs in textile dyeing sludge. Key reaction parameters on CPAHs degradation were optimized by the central composite design as followed: H 2 O 2 concentration of 152 mmol/L, ultrasonic density of 408 W/L, pH value of 3.7, the molar ratio of H 2 O 2 to Fe 2+ of 1.3 and reaction time of 43 min. Under the optimal conditions of the US/Fenton process, the degradation efficiencies of five CPAHs were obtained as 81.23% (benzo[a]pyrene) to 84.98% (benz[a]anthracene), and the benzo[a]pyrene equivalent (BaP eq ) concentrations of five CPAHs declined by 81.22-85.19%, which indicated the high potency of US/Fenton process for removing toxic CPAHs from textile dyeing sludge.

Extending the working pH of nitrobenzene degradation using ultrasonic/heterogeneous Fenton to the alkaline range via amino acid modification.

PubMed

ElShafei, Gamal M S; Yehia, F Z; Dimitry, O I H; Badawi, A M; Eshaq, Gh

2015-11-01

Oxides of iron, α-Fe2O3 (I), and copper, CuO (II) prepared by usual precipitation method without surfactant were used at room temperature in the process of nitrobenzene (10mgL(-1)) degradation at different pH values with ultrasonic at 20kHz. The degradation was complete in 20 and 30min for (I) and (II), respectively in the pH range 2-7 using1.0gL(-1) of solids and 10mM of H2O2. A remarkable decrease in degradation efficiency was recorded on increasing the pH to values higher than the neutral range. This loss in efficiency was cancelled to a great extent through modifying the used oxides with amino acids. Arginine showed higher improving effect to (II) (1:1 weight ration) than glycine or glutamic acid. Modification of both oxides with increasing amounts of arginine increased the degradation efficiency of (I) in a more regular way than in case of (II). However, the extent of improvement due to amino acid modification was higher in case of (II) because of its originally low degradation efficiency in strongly alkaline media. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of ultrasonic energy on dispersion of aggregates and released amounts of organic matter and polyvalent cations

NASA Astrophysics Data System (ADS)

Kaiser, M.; Kleber, M.; Berhe, A. A.

2010-12-01

Aggregates play important roles in soil carbon storage and stabilization. Identification of scale-dependent mechanisms of soil aggregate formation and stability is necessary to predict and eventually manage the flow of carbon through terrestrial ecosystems. Application of ultrasonic energy is a common tool to disperse soil aggregates. In this study, we used ultra sonic energy (100 to 2000 J cm-3) to determine the amount of polyvalent cations and organic matter involved in aggregation processes in three arable and three forest soils that varied in soil mineral composition. To determine the amount of organic matter and cations released after application of different amount of ultrasonic energy, we removed the coarse fraction (>250 µm). The remaining residue (<250 µm) was mixed with water and ultrasonically dispersed by application of 100, 200, 400, 500, 1000, 1500 and 2000 J cm-3 energy. After centrifugation the supernatant was filtered and the solid residue freeze dried before we analyzed the amounts of water-extracted organic carbon (OC), Fe, Al, Ca, Mn, and Mg in the filtrates. The extracted OM and solid residues were further characterized by Fourier Transformed Infra Red spectroscopy and Scanning Electron Microscopy. Our results show a linear increase in amount of dissolved OC with increasing amounts of ultra sonic energy up to 1500 J cm-3 indicating maximum dispersion of soil aggregates at this energy level independent from soil type or land use. In contrast to Mn, and Mg, the amounts of dissolved Ca, Fe, and Al increase with increasing ultra sonic energy up to 1500 J cm-3. At 1500 J cm-3, the absolute amounts of OC, Ca, Fe, and Al released were specific for each soil type, likely indicating differences in type of OM-mineral interactions involved in micro-scaled aggregation processes. The amounts of dissolved Fe, and Al released after an application of 1500 J cm-3 are not related to oxalate- and dithionite- extractable, or total Al content indicating less disintegration of pedogenic oxides or clay minerals due to high levels of ultrasonic energy.

Winery biomass waste degradation by sequential sonication and mixed fungal enzyme treatments.

PubMed

Karpe, Avinash V; Dhamale, Vijay V; Morrison, Paul D; Beale, David J; Harding, Ian H; Palombo, Enzo A

2017-05-01

To increase the efficiency of winery-derived biomass biodegradation, grape pomace was ultrasonicated for 20min in the presence of 0.25M, 0.5Mand1.0MKOH and 1.0MNaOH. This was followed by treatment with a 1:1 (v/v) mix of crude enzyme preparation derived from Phanerochaete chrysosporium and Trametes versicolor for 18h and a further 18h treatment with a 60:14:4:2 percent ratio combination of enzymes derived from Aspergillus niger: Penicillium chrysogenum: Trichoderma harzianum: P. citrinum, repsectively. Process efficiency was evaluated by its comparison to biological only mixed fungal degradation over 16days. Ultrasonication treatment with 0.5MKOH followed by mixed enzyme treatment yielded the highest lignin degradation of about 13%. Cellulase, β-glucosidase, xylanase, laccase and lignin peroxidase activities of 77.9, 476, 5,390.5, 66.7 and 29,230.7U/mL, respectively, were observed during biomass degradation. Gas chromatography-mass spectrometry (GC-MS) analysis of the degraded material identified commercially important compounds such as gallic acid, lithocholic acid, glycolic acid and lactic acid which were generated in considerable quantities. Thus, the combination of sonication pre-treatment and enzymatic degradation has the potential to considerably improve the breakdown of agricultural biomass and produce commercially useful compounds in markedly less time (<40h) with respect to biological only degradation (16days). Copyright © 2016 Elsevier Inc. All rights reserved.

Bioavailability of methyl parathion adsorbed on clay minerals and iron oxide.

PubMed

Cai, Peng; He, Xiaomin; Xue, Aifang; Chen, Hao; Huang, Qiaoyun; Yu, Jun; Rong, Xinming; Liang, Wei

2011-01-30

Adsorption, desorption and degradation by Pseudomonas putida of methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) on montmorillonite, kaolinite and goethite were studied. Metabolic activities of methyl parathion-degrading bacteria P. putida in the presence of minerals were also monitored by microcalorimetry to determine the degradation mechanism of methyl parathion. Montmorillonite presented higher adsorption capacity and affinity for methyl parathion than kaolinite and goethite. The percentage of degradation of methyl parathion adsorbed on minerals by P. putida was in the order of montmorillonite>kaolinite>goethite. The presence of minerals inhibited the exponential growth and the metabolic activity of P. putida. Among the examined minerals, goethite exhibited the greatest inhibitory effect on bacterial activity, while montmorillonite was the least depressing. The biodegradation of adsorbed methyl parathion by P. putida is apparently not controlled by the adsorption affinity of methyl parathion on minerals and may be mainly governed by the activity of the methyl parathion-degrading bacteria. The information obtained in this study is of fundamental significance for the understanding of the behavior of methyl parathion in soil environments. Copyright © 2010 Elsevier B.V. All rights reserved.

Modeling of ultrasonic degradation of non-volatile organic compounds by Langmuir-type kinetics.

PubMed

Chiha, Mahdi; Merouani, Slimane; Hamdaoui, Oualid; Baup, Stéphane; Gondrexon, Nicolas; Pétrier, Christian

2010-06-01

Sonochemical degradation of phenol (Ph), 4-isopropylphenol (4-IPP) and Rhodamine B (RhB) in aqueous solutions was investigated for a large range of initial concentrations in order to analyze the reaction kinetics. The initial rates of substrate degradation and H(2)O(2) formation as a function of initial concentrations were determined. The obtained results show that the degradation rate increases with increasing initial substrate concentration up to a plateau and that the sonolytic destruction occurs mainly through reactions with hydroxyl radicals in the interfacial region of cavitation bubbles. The rate of H(2)O(2) formation decreases with increasing substrate concentration and reaches a minimum, followed by almost constant production rate for higher substrate concentrations. Sonolytic degradation data were analyzed by the models of Okitsu et al. [K. Okitsu, K. Iwasaki, Y. Yobiko, H. Bandow, R. Nishimura, Y. Maeda, Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration OH radicals and azo dyes, Ultrason. Sonochem. 12 (2005) 255-262.] and Seprone et al. [N. Serpone, R. Terzian, H. Hidaka, E. Pelizzetti, Ultrasonic induced dehalogenation and oxidation of 2-, 3-, and 4-chlorophenol in air-equilibrated aqueous media. Similarities with irradiated semiconductor particulates, J. Phys. Chem. 98 (1994) 2634-2640.] developed on the basis of a Langmuir-type mechanism. The five linearized forms of the Okitsu et al.'s equation as well as the non-linear curve fitting analysis method were discussed. Results show that it is not appropriate to use the coefficient of determination of the linear regression method for comparing the best-fitting. Among the five linear expressions of the Okitsu et al.'s kinetic model, form-2 expression very well represent the degradation data for Ph and 4-IPP. Non-linear curve fitting analysis method was found to be the more appropriate method to determine the model parameters. An excellent representation of the experimental results of sonolytic destruction of RhB was obtained using the Serpone et al.'s model. The Serpone et al.'s model gives a worse fit for the sonolytic degradation data of Ph and 4-IPP. These results indicate that Ph and 4-IPP undergo degradation predominantly at the bubble/solution interface, whereas RhB undergoes degradation at both bubble/solution interface and in the bulk solution. (c) 2010 Elsevier B.V. All rights reserved.

Degradation of N-nitrosodimethylamine (NDMA) and its precursor dimethylamine (DMA) in mineral micropores induced by microwave irradiation.

PubMed

He, Yuanzhen; Cheng, Hefa

2016-05-01

Removal of N-nitrosodimethylamine (NDMA) in drinking water treatment poses a significant technical challenge due to its small molecular size, high polarity and water solubility, and poor biodegradability. Degradation of NDMA and its precursor, dimethylamine (DMA), was investigated by adsorbing them from aqueous solution using porous mineral sorbents, followed by destruction under microwave irradiation. Among the mineral sorbents evaluated, dealuminated ZSM-5 exhibited the highest sorption capacities for NDMA and DMA, which decreased with the density of surface cations present in the micropores. In contrast, the degradation rate of the sorbed NDMA increased with the density of surface cations under microwave irradiation. Evolutions of the degradation products and C/N ratio indicate that the sorbed NDMA and DMA could be eventually mineralized under continuous microwave irradiation. The degradation rate was strongly correlated with the bulk temperature of ZSM-5 and microwave power, which is consistent with the mechanism of pyrolysis caused by formation of micro-scale "hot spots" within the mineral micropores under microwave irradiation. Compared to existing treatment options for NDMA removal, microporous mineral sorption coupled with microwave-induced degradation has the unique advantages of being able to simultaneously remove NDMA and DMA and cause their full mineralization, and thus could serve as a promising alternative method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall.

PubMed

Lowe, Premesh S; Duan, Wenbo; Kanfoud, Jamil; Gan, Tat-Hean

2017-11-04

There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers.

Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall

PubMed Central

Kanfoud, Jamil; Gan, Tat-Hean

2017-01-01

There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers. PMID:29113058

Confocal laser scanning, scanning electron, and transmission electron microscopy investigation of Enterococcus faecalis biofilm degradation using passive and active sodium hypochlorite irrigation within a simulated root canal model.

PubMed

Mohmmed, Saifalarab A; Vianna, Morgana E; Penny, Matthew R; Hilton, Stephen T; Mordan, Nicola; Knowles, Jonathan C

2017-08-01

Root canal irrigation is an important adjunct to control microbial infection. The aim of this study was to investigate the effect of 2.5% (wt/vol) sodium hypochlorite (NaOCl) agitation on the removal, killing, and degradation of Enterococcus faecalis biofilm. A total of 45 root canal models were manufactured using 3D printing with each model comprising an 18 mm length simulated root canal of apical size 30 and taper 0.06. E. faecalis biofilms were grown on the apical 3 mm of the models for 10 days. A total of 60 s of 9 ml of 2.5% NaOCl irrigation using syringe and needle was performed, the irrigant was either left stagnant in the canal or agitated using manual (Gutta-percha), sonic, and ultrasonic methods for 30 s. Following irrigation, the residual biofilms were observed using confocal laser scanning, scanning electron, and transmission electron microscopy. The data were analyzed using one-way ANOVA with Dunnett post hoc tests at a level of significance p ≤ .05. Consequence of root canal irrigation indicate that the reduction in the amount of biofilm achieved with the active irrigation groups (manual, sonic, and ultrasonic) was significantly greater when compared with the passive and untreated groups (p < .05). Collectively, finding indicate that passive irrigation exhibited more residual biofilm on the model surface than irrigant agitated by manual or automated (sonic, ultrasonic) methods. Total biofilm degradation and nonviable cells were associated with the ultrasonic group. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Microwave hydrothermal-assisted preparation of novel spinel-NiFe2O4/natural mineral composites as microwave catalysts for degradation of aquatic organic pollutants.

PubMed

Shen, Manli; Fu, Lu; Tang, Jianhua; Liu, Mingyu; Song, Youtao; Tian, Fangyuan; Zhao, Zhigang; Zhang, Zhaohong; Dionysiou, Dionysios D

2018-05-15

In this study, novel spinel-NiFe 2 O 4 /natural mineral (sepiolite, diatomite and kaolinite) composites were developed using microwave (MW) hydrothermal method, and applied in MW-induced catalytic degradation (NiFe 2 O 4 /natural mineral/MW) of organic pollutants such as sodium dodecyl benzene sulfonate (SDBS), azo fuchsine (AF), methyl parathion (MP), and crystal violet (CVL) in solution. Catalytic activities of three NiFe 2 O 4 /natural mineral composites were compared. The effects of material synthesis process parameters such as molar ratios of NiFe 2 O 4 and natural mineral, and pH of precursor solutions for synthesizing catalysts, and degradation parameters such as MW irradiation time and catalyst reuse cycles were also investigated. The principle on NiFe 2 O 4 /natural mineral/MW degradation was provided. The results reveal that organic pollutants in wastewater can be removed completely using NiFe 2 O 4 /natural mineral/MW within minutes. NiFe 2 O 4 /sepiolite shows higher catalytic activity than the others. The calculated degradation rate constants are 1.865, 0.672, 0.472, and 0.329 min -1 for SDBS, AF, MP, and CVL, respectively, using NiFe 2 O 4 /sepiolite/MW system. The performance of NiFe 2 O 4 /natural mineral can be maintained for three reuse cycles. Active species OH, O 2 - , and h + play main roles in NiFe 2 O 4 /sepiolite/MW degradation. Hence, NiFe 2 O 4 /sepiolite/MW technology with rapid and cost-effective degradation, magnetic separation, and no secondary pollution, demonstrates to be promising in treating organic contaminants in wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Aerobic and anaerobic degradation and mineralization of 14C-chitin by water column and sediment inocula of the York River estuary, Virginia.

PubMed Central

Boyer, J N

1994-01-01

Potential rates of chitin degradation (Cd) and mineralization (Cm) by estuarine water and sediment bacteria were measured as a function of inoculum source, temperature, and oxygen condition. In the water column inoculum, 88 to 93% of the particulate chitin was mineralized to CO2 with no apparent lag between degradation and mineralization. No measurable dissolved pool of radiolabel was found in the water column. For the sediment inocula, 70 to 90% of the chitin was degraded while only 55 to 65% was mineralized to CO2. 14C label recoveries in the dissolved pool were 19 to 21% for sand, 17 to 24% in aerobic mud, and 12 to 21% for the anaerobic mud. This uncoupling between degradation and mineralization occurred in all sediment inocula. More than 98% of the initial 14C-chitin was recovered in the three measured fractions. The highest Cd and Cm values, 30 and 27% day-1, occurred in the water column inoculum at 25 degrees C. The lowest Cd and Cm values were found in the aerobic and anaerobic mud inocula incubated at 15 degrees C. Significant differences in Cd and Cm values among water column and sediment inocula as well as between temperature treatments were evident. An increased incubation temperature resulted in shorter lag times before the onset of chitinoclastic bacterial growth, degradation, and mineralization and resulted in apparent Q10 values of 1.1 for water and 1.3 to 2.1 for sediment inocula. It is clear that chitin degradation and mineralization occur rapidly in the estuary and that water column bacteria may be more important in this process than previously acknowledged. PMID:8117075

Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics

NASA Astrophysics Data System (ADS)

Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

2016-08-01

The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process.

Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics

PubMed Central

Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

2016-01-01

The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process. PMID:27484188

Degradation of organic wastewater by hydrodynamic cavitation combined with acoustic cavitation.

PubMed

Yi, Chunhai; Lu, Qianqian; Wang, Yun; Wang, Yixuan; Yang, Bolun

2018-05-01

In this paper, the decomposition of Rhodamine B (RhB) by hydrodynamic cavitation (HC), acoustic cavitation (AC) and the combination of these individual methods (HAC) have been investigated. The degradation of 20 L RhB aqueous solution was carried out in a self-designed HAC reactor, where hydrodynamic cavitation and acoustic cavitation could take place in the same space simultaneously. The effects of initial concentration, inlet pressure, solution temperature and ultrasonic power were studied and discussed. Obvious synergies were found in the HAC process. The combined method achieved the best conversion, and the synergistic effect in HAC was even up to 119% with the ultrasonic power of 220 W in a treatment time of 30 min. The time-independent synergistic factor based on rate constant was introduced and the maximum value reached 40% in the HAC system. Besides, the hybrid HAC method showed great superiority in energy efficiency at lower ultrasonic power (88-176 W). Therefore, HAC technology can be visualized as a promising method for wastewater treatment with good scale-up possibilities. Copyright © 2018 Elsevier B.V. All rights reserved.

Ultrasonically assisted extraction of calcium and ash from char

NASA Astrophysics Data System (ADS)

Mathumba, E. E.; Mbaya, R. K. K.; Kolesnikov, A.

2018-03-01

This study characterized and removed calcium and ash content from char to improve the chemical quality of char as reductant for titanium smelting application. Calcium in char can be classified in two parts: mineral matter and cationic metals associated with organic matrix. Virgin and chemically treated char was characterized by using ISO 1171, wet chemistry methods, ISO 19579, XRF, and B.E.T. methods. In this present work, demineralization of char with mild chemical leachants such as acetic acid, citric acid, gluconic acid and Ethylene Diamine Tetra Acetic acid with three different ultrasonic power input (150 W, 270 W and 300 W) and semi-dual frequency of 40 kHz tank was investigated. Actual power dissipated into the system was calculated from the calorimetric measurement. An optimum set of process parameters are identified and validated. The ultrasound technology was compared with soaking technology to determine the efficiency of ultrasound system for the removal of calcium. The removal of calcium was exponentially higher with ultrasonic treatment than without it. Results revealed that mild chemical reagents do not harm the carbon content of char. It is evident from the results that amongst the leachants used; acetic and citric acid has caused significant removal of mineral phases.

Material State Awareness for Composites Part II: Precursor Damage Analysis and Quantification of Degraded Material Properties Using Quantitative Ultrasonic Image Correlation (QUIC)

PubMed Central

Patra, Subir; Banerjee, Sourav

2017-01-01

Material state awareness of composites using conventional Nondestructive Evaluation (NDE) method is limited by finding the size and the locations of the cracks and the delamination in a composite structure. To aid the progressive failure models using the slow growth criteria, the awareness of the precursor damage state and quantification of the degraded material properties is necessary, which is challenging using the current NDE methods. To quantify the material state, a new offline NDE method is reported herein. The new method named Quantitative Ultrasonic Image Correlation (QUIC) is devised, where the concept of microcontinuum mechanics is hybrid with the experimentally measured Ultrasonic wave parameters. This unique combination resulted in a parameter called Nonlocal Damage Entropy for the precursor awareness. High frequency (more than 25 MHz) scanning acoustic microscopy is employed for the proposed QUIC. Eight woven carbon-fiber-reinforced-plastic composite specimens were tested under fatigue up to 70% of their remaining useful life. During the first 30% of the life, the proposed nonlocal damage entropy is plotted to demonstrate the degradation of the material properties via awareness of the precursor damage state. Visual proofs for the precursor damage states are provided with the digital images obtained from the micro-optical microscopy, the scanning acoustic microscopy and the scanning electron microscopy. PMID:29258256

Enhancement and inhibition effects of water matrices during the sonochemical degradation of the antibiotic dicloxacillin.

PubMed

Villegas-Guzman, Paola; Silva-Agredo, Javier; Giraldo-Aguirre, Ana L; Flórez-Acosta, Oscar; Petrier, Christian; Torres-Palma, Ricardo A

2015-01-01

The sonochemical degradation of dicloxacillin (DXC) was studied in both synthetic and natural waters. Degradation routes and the effect of experimental conditions such as pH, initial DXC concentration and ultrasonic power were evaluated. Experiments were carried out with a fixed frequency (600kHz). The best performances were achieved using acidic media (pH=3) and high power (60W). The degradation process showed pseudo-first order kinetics as described by the Okitsu model. To evaluate water matrix effects, substrate degradation, in the presence of Fe(2+) and organic compounds such as glucose and 2-propanol, was studied. A significant improvement was achieved with Fe(2+) (1.0mM). Inhibition of the degradation process was observed at a relatively high concentration of 2-propanol (4.9mM), while glucose did not show any effect. Natural water showed an interesting effect: for a low concentration of DXC (6.4μM), an improvement in the degradation process was observed, while at a higher concentration of DXC (0.43mM), degradation was inhibited. Additionally, the extent of degradation of the process was evaluated through the analysis of chemical oxygen demand (COD), antimicrobial activity, total organic carbon (TOC) and biochemical oxygen demand (BOD5). A 30% removal of COD was achieved after the treatment and no change in the TOC was observed. Antimicrobial activity was eliminated after 360min of ultrasonic treatment. After 480min of treatment, a biodegradable solution was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of nuclear graphite elastic properties using laser ultrasonic methods

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

Zeng, Fan W; Han, Karen; Olasov, Lauren R

2015-01-01

Laser ultrasonic methods have been used to characterize the elastic behaviors of commercially-available and legacy nuclear graphites. Since ultrasonic techniques are sensitive to various aspects of graphite microstructure including preferred grain orientation, microcrack orientation and porosity, laser ultrasonics is a candidate technique for monitoring graphite degradation and structural integrity in environments expected in high-temperature, gas-cooled nuclear reactors. Aspects of materials texture can be assessed by studying ultrasonic wavespeeds as a function of propagation direction and polarization. Shear wave birefringence measurements, in particular, can be used to evaluate elastic anisotropy. In this work, laser ultrasonic measurements of graphite moduli have beenmore » made to provide insight into the relationship between the microstructures and the macroscopic stiffnesses of these materials. In particular, laser ultrasonic measurements have been made using laser line sources to produce shear waves with specific polarizations. By varying the line orientation relative to the sample, shear wave birefringence measurements have been recorded. Results from shear wave birefringence measurements show that an isostatically molded graphite, such as PCIB, behaves isotropically, while an extruded graphite, such as H-451, displays significant ultrasonic texture. Graphites have complicated microstructures that depend on the manufacturing processes used, and ultrasonic texture in these materials could originate from grain orientation and preferred microcrack alignment. Effects on material isotropy due to service related microstructural changes are possible and the ultimate aim of this work is to determine the degree to which these changes can be assessed nondestructively using laser ultrasonics measurements« less

Piezo-Catalytic Effect on the Enhancement of the Ultra-High Degradation Activity in the Dark by Single- and Few-Layers MoS2 Nanoflowers.

PubMed

Wu, Jyh Ming; Chang, Wei En; Chang, Yu Ting; Chang, Chih-Kai

2016-05-01

Single- and few-layer MoS2 nanoflowers are first discovered to have a piezo-catalyst effect, exhibiting an ultra-high degradation activity in the dark by introducing external mechanical strains. The degradation ratio of the Rhodamine-B dye solution reaches 93% within 60 s under ultrasonic-wave assistance in the dark. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shearing stability of lubricants

NASA Technical Reports Server (NTRS)

Shiba, Y.; Gijyutsu, G.

1984-01-01

Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

Ultrasonic technique for detection of liquids in copper tubing process lines

NASA Astrophysics Data System (ADS)

Dudley, W. A.

1980-10-01

An ultrasonic pulse-echo method developed for semiquantitative measurement of liquid levels in copper tubing is described. This ultrasonic approach is of particular value when used as a pre-maintenance diagnostic tool in repairing process lines containing hazardous liquids. Performance tests show that water and similar liquids can be directly detected to fill levels as low as 1/16 in. For water fills below 1/16 in., direct level detection is impractical because of signal resolution limitations. However, this fill condition is indirectly measurable and is detected by the effect of observed degradation of the adjacent wall echo pattern. Fill conditions for liquids associated with high sound attenuation such as oil can be indirectly determined.

Geophysical Signatures to Monitor Fluids and Mineralization for CO2 Sequestration in Basalts

NASA Astrophysics Data System (ADS)

Otheim, L. T.; Adam, L.; Van Wijk, K.; Batzle, M. L.; Mcling, T. L.; Podgorney, R. K.

2011-12-01

Carbon dioxide sequestration in large reservoirs can reduce emissions of this green house gas into the atmosphere. Basalts are promising host rocks due to their volumetric extend, worldwide distribution, and recent observations that CO2-water mixtures react with basalt minerals to precipitate as carbonate minerals, trapping the CO2. The chemical reaction between carbonic acid and minerals rich in calcium, magnesium and iron precipitates carbonates in the pore space. This process would increase the elastic modulus and velocity of the rock. At the same time, the higher compressibility of CO2 over water changes the elastic properties of the rock, decreasing the saturated rock bulk modulus and the P-wave velocity. Reservoirs where the rock properties change as a result of fluid or pressure changes are commonly monitored with seismic methods. Here we present experiments to study the feasibility of monitoring CO2 migration in a reservoir and CO2-rock reactions for a sequestration scenario in basalts. Our goal is to measure the rock's elastic response to mineralization with non-contacting ultrasonic lasers, and the effect of fluid substitution at reservoir conditions at seismic and ultrasonic frequencies. For the fluid substitution experiment we observe changes in the P- and S-wave velocities when saturating the sample with super-critical (sc) CO2, CO2-water mixtures and water alone for different pore and confining pressures. The bulk modulus of the rock is significantly dependent on frequency in the 2~to 106~Hz range, for CO2-water mixtures and pure water saturations. Dry and pure CO2 (sc or gas) do not show a frequency dependence on the modulus. Moreover, the shear wave modulus is not dispersive for either fluid. The frequency dependence of the elastic parameters is related to the attenuation (1/Q) of the rock. We will show the correlation between frequency dependent moduli and attenuation data for the different elastic moduli of the rocks. Three other basalt samples were stored in a pressure chamber with a sc CO2-water solution to study the effect of mineralization on the elastic properties of the rock. The rock elastic properties are recorded with non-contacting ultrasonic lasers at room conditions. After 15 weeks the first post-mineralization scan showed differences in the rock velocities with respect to the pre-mineralization scan. The analysis is done through coda wave interferometry and direct arrivals. The samples were inserted back into the pressure vessel for continuing mineralization and subsequent scans. Finally, we will discuss the applicability of Gassmann's equation and how the combination of mineralization together with CO2-water mixture affects the velocity of waves in basalt rocks.

Atrazine and its metabolites degradation in mineral salts medium and soil using an enrichment culture.

PubMed

Kumar, Anup; Singh, Neera

2016-03-01

An atrazine-degrading enrichment culture was used to study degradation of atrazine metabolites viz. hydroxyatrazine, deethylatrazine, and deisopropylatrazine in mineral salts medium. Results suggested that the enrichment culture was able to degrade only hydroxyatrazine, and it was used as the sole source of carbon and nitrogen. Hydroxyatrazine degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as the additional sources of carbon and nitrogen, respectively. The enrichment culture could degrade high concentrations of atrazine (up to 110 μg/mL) in mineral salts medium, and neutral pH was optimum for atrazine degradation. Further, except in an acidic soil, enrichment culture was able to degrade atrazine in three soil types having different physico-chemical properties. Raising the pH of acidic soil to neutral or alkaline enabled the enrichment culture to degrade atrazine suggesting that acidic pH inhibited atrazine-degrading ability. The study suggested that the enrichment culture can be successfully utilized to achieve complete degradation of atrazine and its persistent metabolite hydroxyatrazine in the contaminated soil and water.

Comparison of Enzymatic and Ultrasonic Extraction of Albumin from Defatted Pumpkin (Cucurbita pepo)
Seed Powder

PubMed Central

Tu, Gia Loi; Bui, Thi Hoang Nga; Tran, Thi Thu Tra; Ton, Nu Minh Nguyet

2015-01-01

Summary In this study, ultrasound- and enzyme-assisted extractions of albumin (water-soluble protein group) from defatted pumpkin (Cucurbita pepo) seed powder were compared. Both advanced extraction techniques strongly increased the albumin yield in comparison with conventional extraction. The extraction rate was two times faster in the ultrasonic extraction than in the enzymatic extraction. However, the maximum albumin yield was 16% higher when using enzymatic extraction. Functional properties of the pumpkin seed albumin concentrates obtained using the enzymatic, ultrasonic and conventional methods were then evaluated. Use of hydrolase for degradation of cell wall of the plant material did not change the functional properties of the albumin concentrate in comparison with the conventional extraction. The ultrasonic extraction enhanced water-holding, oil-holding and emulsifying capacities of the pumpkin seed albumin concentrate, but slightly reduced the foaming capacity, and emulsion and foam stability. PMID:27904383

Comparison of Enzymatic and Ultrasonic Extraction of Albumin from Defatted Pumpkin (Cucurbita pepo)
Seed Powder.

PubMed

Tu, Gia Loi; Bui, Thi Hoang Nga; Tran, Thi Thu Tra; Ton, Nu Minh Nguyet; Man Le, Van Viet

2015-12-01

In this study, ultrasound- and enzyme-assisted extractions of albumin (water-soluble protein group) from defatted pumpkin ( Cucurbita pepo ) seed powder were compared. Both advanced extraction techniques strongly increased the albumin yield in comparison with conventional extraction. The extraction rate was two times faster in the ultrasonic extraction than in the enzymatic extraction. However, the maximum albumin yield was 16% higher when using enzymatic extraction. Functional properties of the pumpkin seed albumin concentrates obtained using the enzymatic, ultrasonic and conventional methods were then evaluated. Use of hydrolase for degradation of cell wall of the plant material did not change the functional properties of the albumin concentrate in comparison with the conventional extraction. The ultrasonic extraction enhanced water-holding, oil-holding and emulsifying capacities of the pumpkin seed albumin concentrate, but slightly reduced the foaming capacity, and emulsion and foam stability.

Ultrasonic inspection of carbon fiber reinforced plastic by means of sample-recognition methods

NASA Technical Reports Server (NTRS)

Bilgram, R.

1985-01-01

In the case of carbon fiber reinforced plastic (CFRP), it has not yet been possible to detect nonlocal defects and material degradation related to aging with the aid of nondestructive inspection method. An approach for overcoming difficulties regarding such an inspection involves an extension of the ultrasonic inspection procedure on the basis of a use of signal processing and sample recognition methods. The basic concept involved in this approach is related to the realization that the ultrasonic signal contains information regarding the medium which is not utilized in conventional ultrasonic inspection. However, the analytical study of the phyiscal processes involved is very complex. For this reason, an empirical approach is employed to make use of the information which has not been utilized before. This approach uses reference signals which can be obtained with material specimens of different quality. The implementation of these concepts for the supersonic inspection of CFRP laminates is discussed.

Carbohydrates protect protein against abiotic fragmentation by soil minerals

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

Reardon, Patrick N.; Walter, Eric D.; Marean-Reardon, Carrie L.

The degradation and turnover of soil organic matter is an important part of global carbon cycling and of particular importance with respect to attempts to predict the response of ecosystems to global climate change. Thus, it is important to mechanistically understand the processes by which organic matter can be degraded in the soil environment, including contact with reactive or catalytic mineral surfaces. We have characterized the outcome of the interaction of two minerals, birnessite and kaolinite, with two disaccharides, cellobiose and trehalose. These results show that birnessite reacts with and degrades the carbohydrates, while kaolinite does not. The reaction ofmore » disaccharides with birnessite produces Mn(II), indicating that degradation of the disaccharides is the result of their oxidation by birnessite. Furthermore, we find that both sugars can inhibit the degradation of a model protein by birnessite, demonstrating that the presence of one organic constituent can impact abiotic degradation of another. Therefore, both the reactivity of the mineral matrix and the presence of certain organic constituents influence the outcomes of abiotic degradation. These results suggest the possibility that microorganisms may be able to control the functionality of exoenzymes through the concomitant excretion of protective organic substances, such as those found in biofilms.« less

Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization.

PubMed

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

2001-06-01

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

Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

PubMed

Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

2016-11-15

The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative ultrasonic evaluation of mechanical properties of engineering materials

NASA Technical Reports Server (NTRS)

Vary, A.

1978-01-01

Current progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength properties of engineering materials is reviewed. Even where conventional NDE techniques have shown that a part is free of overt defects, advanced NDE techniques should be available to confirm the material properties assumed in the part's design. There are many instances where metallic, composite, or ceramic parts may be free of critical defects while still being susceptible to failure under design loads due to inadequate or degraded mechanical strength. This must be considered in any failure prevention scheme that relies on fracture analysis. This review will discuss the availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions.

The Detection of Burn-Through Weld Defects Using Noncontact Ultrasonics

PubMed Central

Abbasi, Zeynab; Yuhas, Donald; Zhang, Lu; Basantes, Alexandra-Del-Carmen; Tehrani, Niloofar Nabili; Ozevin, Didem; Indacochea, Ernesto

2018-01-01

Nearly all manufactured products in the metal industry involve welding. The detection and correction of defects during welding improve the product reliability and quality, and prevent unexpected failures. Nonintrusive process control is critical for avoiding these defects. This paper investigates the detection of burn-through damage using noncontact, air-coupled ultrasonics, which can be adapted to the immediate and in-situ inspection of welded samples. The burn-through leads to a larger volume of degraded weld zone, providing a resistance path for the wave to travel which results in lower velocity, energy ratio, and amplitude. Wave energy dispersion occurs due to the increase of weld burn-through resulting in higher wave attenuation. Weld sample micrographs are used to validate the ultrasonic results. PMID:29342875

Ultrasound enhanced glucose release from corn in ethanol plants.

PubMed

Khanal, Samir Kumar; Montalbo, Melissa; van Leeuwen, J; Srinivasan, Gowrishankar; Grewell, David

2007-12-01

This work evaluated the use of high power ultrasonic energy to treat corn slurry in dry corn milling ethanol plants to enhance liquefaction and saccharification for ethanol production. Corn slurry samples obtained before and after jet cooking were subjected to ultrasonic pretreatment for 20 and 40 s at amplitudes of vibration ranging from 180 to 299 microm(pp) (peak to peak amplitude in microm). The resulting samples were then exposed to enzymes (alpha-amylase and glucoamylase) to convert cornstarch into glucose. A comparison of scanning electron micrographs of raw and sonicated samples showed the development of micropores and the disruption of cell walls in corn mash. The corn particle size declined nearly 20-fold following ultrasonic treatment at high power settings. The glucose release rate from sonicated samples increased as much as threefold compared to the control group. The efficiency of ultrasound exceeded 100% in terms of energy gain from the sugar released over the ultrasonic energy supplied. Enzymatic activity was enhanced when the corn slurry was sonicated with simultaneous addition of enzymes. This finding suggests that the ultrasonic energy did not degrade or denature the enzymes during the pretreatment.

Effect of ultrasonic and ozone pre-treatments on pharmaceutical waste activated sludge's solubilisation, reduction, anaerobic biodegradability and acute biological toxicity.

PubMed

Pei, Jin; Yao, Hong; Wang, Hui; Shan, Dan; Jiang, Yichen; Ma, Lanqianya; Yu, Xiaohua

2015-09-01

Ultrasonic and ozone pre-treatment technologies were employed in this study to improve the anaerobic digestion efficiency of pharmaceutical waste activated sludge. The sludge solubilisation achieved 30.01% (150,000 kJ/kg TS) and 28.10% (0.1g O3/g TS) after ultrasonic treatment and ozone treatment. The anaerobic biodegradability after ultrasonic treatment was higher compared to ozonation due to the higher cumulative methane volume observed after 6 days (249 ml vs 190 ml). The ozonated sludge released the highest concentration of Cu(2+) into the liquid phase (6.640 mg L(-1)) compared to 0.530 mg/L for untreated sludge and 0.991 mg/L for sonicated sludge. The acute toxicity test measured by luminescent bacteria showed that anaerobic digestion could degrade toxic compounds and result in a reduction in toxicity. The main mechanism of action led to some differences in the treated sludge exhibiting higher potential for methane production from pharmaceutical waste sludge with ultrasonic treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of a magnetic N-Fe/AC catalyst for aqueous pharmaceutical treatment in heterogeneous sonication system.

PubMed

Zhang, Nan; Zhao, He; Zhang, Guangming; Chong, Shan; Liu, Yucan; Sun, Liyan; Chang, Huazhen; Huang, Ting

2017-02-01

High efficiency and facile separation are desirable for catalysts used in water treatment. In this study, a magnetic catalyst (nitrogen doped iron/activated carbon) was prepared and used for pharmaceutical wastewater treatment. The catalyst was characterized using BET, SEM, XRD, VSM and XPS. Results showed that iron and nitrogen were successfully loaded and doped, magnetic Fe 2 N was formed, large amount of active surface oxygen and Fe(II) were detected, and the catalyst could be easily separated from water. Diclofenac was then degraded using the catalyst in ultrasound system. The catalyst showed high catalytic activity with 95% diclofenac removal. Analysis showed that ·OH attack of diclofenac was a main pathway, and then ·OH generation mechanism was clarified. The effects of catalyst dosage, sonication time, ultrasonic density, initial pH, and inorganic anions on diclofenac degradation were studied. Sulfate anion enhanced the degradation of diclofenac. Mechanism in the catalytic ultrasonic process was analyzed and reactions were clarified. Large quantity of oxidants was generated on the catalyst surface, including ·OH, O 2 - , O - and HO 2 ·, which degraded diclofenac efficiently. In the solution and interior of cavitation bubbles, ·OH and "hot spot" effects contributed to the degradation of diclofenac. Reuse of the catalyst was further investigated to enhance its economy, and the catalyst maintained activity after seven uses. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Mirzazadeh, Hoda; Lashanizadegan, Maryam

2018-05-01

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

Concrete Shield Performance of the VSC-17 Spent Nuclear Fuel Cask

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

Koji Shirai

2006-04-01

The VSC-17 Spent Nuclear Fuel Storage Cask was surveyed for degradation of the concrete shield by radiation measurement, temperature measurement, and ultrasonic testing. No general loss of shielding function was identified.

Mineralization of polycyclic aromatic hydrocarbons by the white rot fungus Pleurotus ostreatus

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

Bezalel, L.; Hadar, Y.; Cerniglia, C.E.

White rot fungi, including Pleurotus ostreatus, have the ability to efficiently degrade lignin, a naturally occurring aromatic polymer. Previous work has found these organisms were able to degrade PAHs and in some cases to mineralize them; most of the work was done with Phanerochaete chrysosporium. P. ostreatus differs from P. chrysosporium in its lignin degradation mechanism. In this study, enzymatic activities were monitored during P. ostreatus growth in the presence of PAHs and the fungus`s ability to mineralize catechol and various PAHs was demonstrated. 29 refs., 3 figs., 1 tab.

Soil Minerals Affect Extracellular Enzyme Activities in Cold and Warm Environments

NASA Astrophysics Data System (ADS)

Yang, Z.; Morin, M. M.; Graham, D. E.; Wullschleger, S. D.; Gu, B.

2017-12-01

Extracellular enzymes are mainly responsible for degrading and cycling soil organic matter (SOM) in both cold and warm terrestrial ecosystems. Minerals can play important roles in affecting soil enzyme activities, however, the interactions between enzyme and soil minerals remain poorly understood. In this study, we developed a model soil-enzyme system to examine the mineral effects on a hydrolytic enzyme (i.e., β-glucosidase) under both cold (4°C) and relatively warm (20 and 30°C) conditions. Minerals including iron oxides and clays (e.g., kaolinite and montmorillonite) were used to mimic different types of soils, and enzyme adsorption experiments were conducted to determine the enzyme interactions with different mineral surfaces. Time-series experiments were also carried out to measure enzymatic degradation of the organic substrates, such as cellobiose and indican. We observed that fractions of adsorbed enzyme and the hydrolytic activity were higher on iron oxides (e.g., hematite) compared to kaolinite and montmorillonite at given experimental conditions. The degradation of cellobiose was significantly faster than that of indican in the presence of minerals. We also found that the adsorption of enzyme was not dependent on the mineral surface areas, but was controlled by the mineral surface charge. In addition, temperature increase from 4 to 30°C enhanced mineral-assisted glucosidase hydrolysis by 2 to 4 fold, suggesting greater degradation under warmer environments. The present work demonstrates that the enzyme activity is influenced not only by the soil temperature but also by the surface chemistry of soil minerals. Our results highlight the need to consider the physical and chemical properties of minerals in biogeochemical models, which could provide a better prediction for enzyme-facilitated SOM transformations in terrestrial ecosystems.

Assessment of bioavailability of pesticides in soils and identification of pesticide degradation drivers using the in-situ Mass Distribution Quotient (iMDQ)

NASA Astrophysics Data System (ADS)

Folberth, Christian

2010-05-01

The in-situ Mass Distribution Quotient (iMDQ) has recently been shown to reliably describe the bioavailability and mineralization of the widely applied pesticide isoproturon in agricultural soils. It is determined by pore water extraction from previously incubated soil samples and subsequent assessment of the mass distribution between solid and liquid phase. The method was verified by comparing the bioavailability with co-metabolic mineralization in soils under optimum microbial soil conditions (water tension -15 kPa and bulk density 1.3 g cm-3). A comparison of the results with the chemical partitioning assessed by the Kd method has shown a higher accuracy of the new method. By combining the iMDQ/pore water extraction method with mineralization of the pesticide under optimum microbial conditions in the soils, further information about mineralization and degradation processes could be obtained or confirmed: a) Metabolically outstanding soils could be identified due to inconsistency between bioavailability and mineralization when compared to the co-metabolic soils. In a metabolically hampered soil, the mineralization was very low compared to the bioavailability and in a soil with metabolically IPU degrading microorganisms the mineralization was extremely high despite low bioavailability. b) Analysis of metabolite patterns in soil water fractions of a degradation experiment allowed for an additional identification of the metabolic status of the soil. In co-metabolic soils, the diversity of metabolites increased proportionally with the degree of mineralization of the parent compound, whereas in a metabolically hampered soil the metabolite pattern was very diverse despite low mineralization. c) A quite stable fractioning between total mineralization of the parent compound to CO2 and build-up of non-extractable bound residues was found. This is a hint that also during co-metabolic degradation that can up to now not be attributed to a certain group of microorganisms, very similar processes take place in different soils. d) It could be shown that soil parameters governing the bioavailability of the compound differ between soils. Although TOC and pH could again be identified as the most important factors for the sorption strength of soils towards isoproturon, the bioavailability itself was driven by a combination of water content and sorption strength that was unique for each soil sample. f) The partitioning of parent compound and primary metabolites remained quite stable during the degradation and mineralization. Further investigations focusing on the microbial side of co-metabolic degradation are in progress. In the future, the method could be used to investigate more compounds, the effectiveness of methods to increase bioavailability in-situ without the need for degradation experiments, and the identification and analysis of degradation pathways in-situ. Other processes that are important for risk assessment, like leaching, have already been investigated with similar methods.

Testing the ecotoxicology of vegetable versus mineral based lubricating oils: 1. Degradation rates using tropical marine microbes.

PubMed

Mercurio, Philip; Burns, Kathryn A; Negri, Andrew

2004-05-01

Vegetable-derived lubricants (VDL) might be more biodegradable than mineral-derived lubricants (MDL) due to the absence of high molecular weight aromatics, but this remains largely untested in tropical conditions. In this laboratory study, the degradation rates of 2-stroke, 4-stroke and hydraulic VDLs were compared with their MDL counterparts in the presence of mangrove and coral reef microbial communities. While MDLs were comprised largely of unresolved saturated and some aromatic hydrocarbons, their VDL counterparts contained, potentially more degradable, fatty acid methyl esters. Degradation of some VDL was observed by day 7, with the 2-stroke VDL markedly consumed by mangrove microorganisms and the hydraulic VDL degraded by both microorganism communities after this short period. All of the VDL groups were significantly more degraded than the comparable MDLs mineral oil lubricants over 14 days in the presence of either mangrove or coral reef microbial communities. In general the mangrove-sourced microorganisms more efficiently degraded the lubricants than reef-sourced microorganisms.

Photo-Fenton Degradation of Organic Dyes Based on a Fe₃O₄ Nanospheres/Biomass Composite Loaded Column.

PubMed

Zheng, Kai; Zhang, Jubo; Wang, Yan; Gao, Longxue; Di, Mingyu; Yuan, Fang; Bao, Wenhui; Yang, Tao; Liang, Daxin

2018-06-01

In order to deal with pollution of organic dyes, magnetic Fe3O4 nanospheres (NPs) with an average diameter of 202 ± 0.5 nm were synthesized by a solvothermal method at 200 °C, and they can efficiently degrade organic dyes (methylene blue (MB), rhodamine B (RhB) and xylenol orange (XO)) aqueous solutions (20 mg/L) within 1 min. Based on this Fenton reagent, Fe3O4 NPs/biomass composite degradation column was made using sawdust as substrate, and it can efficiently degrade organic dyes continually. More importantly, the composite can be regenerated just by an ultrasonic treatment, and its degradation performance almost remains the same.

Ultrasonic disintegration of biosolids for improved biodegradation.

PubMed

Nickel, Klaus; Neis, Uwe

2007-04-01

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

Degradation of alkylphenol ethoxylate surfactants in water with ultrasonic irradiation

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

Destaillats, H.; Hung, H.M.; Hoffmann, M.R.

2000-01-15

During the last years, many efforts have been devoted to the elimination of alkylphenol ethoxylate surfactants from aqueous systems. In this paper, the sonochemical degradation of aqueous solutions of Triton X-100 was performed at an ultrasonic frequency of 358 kHz and an applied power of 50 W. Analysis of the reaction products by HPLC-ES-MS suggests that the hydrophobic alkyl chain is the preferential site for oxidation. Alkylphenol, or short-chain ethoxylated phenols, were not generated as byproducts. To verify this hypothesis, the sonochemical degradation of the corresponding alkylphenols (e.g., tertoctylphenol) was performed under the same conditions; in these cases, similar ratemore » constants and products were observed. These results differ from those reported for the biodegradation of alkylphenol ethoxylates. A substantial increase in the rate constant was observed for the degradation of Triton X-100 below its critical micelle concentration. This observation indicates that micelle formation serves to effectively isolate the free surfactant monomers from the water-air interface of the oscillating cavitation bubbles, thus decreasing the overall efficiency of the sonochemical process. The hydrophobic tail of the molecule is no longer exposed directly to the bubble hot spot when it is pointed into the core of the micelles.« less

Development of Fe3O4/ZrO2 Composite Powered by Nanographene Platelets (NGP) for Degradation of Water Pollutants via Photo- and Sonocatalysis

NASA Astrophysics Data System (ADS)

Kristianto, Yogi; Taufik, Ardiansyah; Saleh, Rosari

2017-03-01

In this study, a series of Fe3O4/ZrO2/nanographene platelets (NGP) composite, with various weight percent (wt%) of NGP (5%, 10% and 15%), were prepared successfully using ultrasonic-assisted followed by simple hydrothermal method. Their physicochemical properties were fairly characterized by X-ray diffraction, fourier transform infrared and thermal gravimetric analysis. Furthermore, their catalytic activities were investigated toward anionic congo red (CR) and cationic methylene blue (MB) as models of organic pollutant under ultraviolet (UV) and ultrasonic (US) irradiation, respectively. The experimental results showed that the incorporation of NGP in Fe3O4/ZrO2 composite improved its efficiency in degrading CR and MB and became maximum at 10wt% of NGP. In addition, the role of active radicals involved in catalytic activities were discussed.

Synergism between ultrasonic pretreatment and white rot fungal enzymes on biodegradation of wheat chaff.

PubMed

Sabarez, Henry; Oliver, Christine Maree; Mawson, Raymond; Dumsday, Geoff; Singh, Tanoj; Bitto, Natalie; McSweeney, Chris; Augustin, Mary Ann

2014-11-01

Lignocellulosic biomass samples (wheat chaff) were pretreated by ultrasound (US) (40kHz/0.5Wcm(-2)/10min and 400kHz/0.5Wcm(-2)/10min applied sequentially) prior to digestion by enzyme extracts obtained from fermentation of the biomass with white rot fungi (Phanerochaete chrysosporium or Trametes sp.). The accessibility of the cellulosic components in wheat chaff was increased, as demonstrated by the increased concentration of sugars produced by exposure to the ultrasound treatment prior to enzyme addition. Pretreatment with ultrasound increased the concentration of lignin degradation products (guaiacol and syringol) obtained from wheat chaff after enzyme addition. In vitro digestibility of wheat chaff was also enhanced by the ultrasonics pretreatment in combination with treatment with enzyme extracts. Degradation was enhanced with the use of a mixture of the enzyme extracts compared to that for a single enzyme extract. Copyright © 2014. Published by Elsevier B.V.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2017-12-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2018-02-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

30 CFR 285.824 - How must I conduct self-inspections?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Section 285.824 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER... months; (2) The type of inspection employed, (i.e., visual, magnetic particle, ultrasonic testing); and...

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation.

PubMed

Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui

2015-08-15

Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89-94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Method and apparatus for measuring surface contour on parts with elevated temperatures

DOEpatents

Horvath, Mark S.; Nance, Roy A.; Cohen, George H.; Fodor, George

1991-01-01

The invention is directed to a method and apparatus for measuring the surface contour of a test piece, such as the bow of a radioactive fuel rod, which is completely immersed in water. The invention utilizes ultrasonic technology and is capable of measuring surface contours of test pieces which are at a higher temperature than the surrounding water. The presence of a test piece at a higher temperature adversely affects the distance measurements by causing thermal variations in the water near the surface of the test piece. The contour measurements depend upon a constant temperature of the water in the path of the ultrasonic wave to provide a constant acoustical velocity (the measurement is made by the time of flight measurement for an ultrasonic wave). Therefore, any variations of water temperature near the surface will introduce errors degrading the measurement. The present invention overcomes these problems by assuring that the supply of water through which the ultrasonic waves travel is at a predetermined and constant temperature.

Pathogenic prion protein is degraded by a manganese oxide mineral found in soils

USGS Publications Warehouse

Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

2009-01-01

Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.

Natural attenuation is enhanced in previously contaminated and coniferous forest soils.

PubMed

Kauppi, Sari; Romantschuk, Martin; Strömmer, Rauni; Sinkkonen, Aki

2012-01-01

Prevalence of organic pollutants or their natural analogs in soil is often assumed to lead to adaptation in the bacterial community, which results in enhanced bioremediation if the soil is later contaminated. In this study, the effects of soil type and contamination history on diesel oil degradation and bacterial adaptation were studied. Mesocosms of mineral and organic forest soil (humus) were artificially treated with diesel oil, and oil hydrocarbon concentrations (GC-FID), bacterial community composition (denaturing gradient gel electrophoresis, DGGE), and oil hydrocarbon degraders (DGGE + sequencing of 16S rRNA genes) were monitored for 20 weeks at 16°C. Degradation was advanced in previously contaminated soils as compared with pristine soils and in coniferous organic forest soil as compared with mineral soil. Contamination affected bacterial community composition especially in the pristine mineral soil, where diesel addition increased the number of strong bands in the DGGE gel. Sequencing of cloned 16S rRNA gene fragments and DGGE bands showed that potential oil-degrading bacteria were found in mineral and organic soils and in both pristine and previously contaminated mesocosms. Fast oil degradation was not associated with the presence of any particular bacterial strain in soil. We demonstrate at the mesocosm scale that previously contaminated and coniferous organic soils are superior environments for fast oil degradation as compared with pristine and mineral soil environments. These results may be utilized in preventing soil pollution and planning soil remediation.

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.

Assessment of damage in ceramics and ceramic matrix composites using ultrasonic techniques

NASA Technical Reports Server (NTRS)

Chu, Y. C.; Baaklini, G. Y.; Rokhlin, S.I.

1993-01-01

This paper addresses the application of ultrasonic sensing to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock or oxidation at elevated temperatures, which often results in elastic anisotropy. This damaged-induced anisotropy is determined by measuring the velocities of ultrasonic waves in different propagation directions. Thermal shock damage is assessed in ceramic samples of reaction bonded silicon nitride (RBSN). Thermal shock treatment from different temperatures up to 1000 C is applied to produce the microcracks. Results indicate that most microcracks produced by thermal shock are located near sample surfaces. Ultrasonic measurements using the surface wave method are found to correlate well with measurements of degradation of mechanical properties obtained independently by other authors using destructive methods. Oxidation damage is assessed in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hr. The Youngs' modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1200 C. This agrees well with the results of destructive tests by other authors. On the other hand, the transverse moduli obtained from ultrasonic measurements decrease continually until 1200 C. Measurements on the shear stiffnesses show behavior similar to the transverse moduli. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.

30 CFR 585.824 - How must I conduct self-inspections?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Section 585.824 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF Environmental and... inspection employed, (i.e., visual, magnetic particle, ultrasonic testing); and (3) A summary of the...

30 CFR 585.824 - How must I conduct self-inspections?

Code of Federal Regulations, 2012 CFR

2012-07-01

... Section 585.824 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF Environmental and... inspection employed, (i.e., visual, magnetic particle, ultrasonic testing); and (3) A summary of the...

30 CFR 585.824 - How must I conduct self-inspections?

Code of Federal Regulations, 2013 CFR

2013-07-01

... Section 585.824 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF Environmental and... inspection employed, (i.e., visual, magnetic particle, ultrasonic testing); and (3) A summary of the...

Dental hard tissue characterization using laser-based ultrasonics

NASA Astrophysics Data System (ADS)

Blodgett, David W.; Massey, Ward L.

2003-07-01

Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

A novel imaging technique based on the spatial coherence of backscattered waves: demonstration in the presence of acoustical clutter

NASA Astrophysics Data System (ADS)

Dahl, Jeremy J.; Pinton, Gianmarco F.; Lediju, Muyinatu; Trahey, Gregg E.

2011-03-01

In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are often attributed to phase aberration and clutter. Phase aberration degrades image quality by distorting the transmitted and received pressure waves, while clutter degrades image quality by introducing incoherent acoustical interference into the received pressure wavefront. Although significant research efforts have pursued the correction of image degradation due to phase aberration, few efforts have characterized or corrected image degradation due to clutter. We have developed a novel imaging technique that is capable of differentiating ultrasonic signals corrupted by acoustical interference. The technique, named short-lag spatial coherence (SLSC) imaging, is based on the spatial coherence of the received ultrasonic wavefront at small spatial distances across the transducer aperture. We demonstrate comparative B-mode and SLSC images using full-wave simulations that include the effects of clutter and show that SLSC imaging generates contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) that are significantly better than B-mode imaging under noise-free conditions. In the presence of noise, SLSC imaging significantly outperforms conventional B-mode imaging in all image quality metrics. We demonstrate the use of SLSC imaging in vivo and compare B-mode and SLSC images of human thyroid and liver.

An Ultrasonic Multi-Beam Concentration Meter with a Neuro-Fuzzy Algorithm for Water Treatment Plants

PubMed Central

Lee, Ho-Hyun; Jang, Sang-Bok; Shin, Gang-Wook; Hong, Sung-Taek; Lee, Dae-Jong; Chun, Myung Geun

2015-01-01

Ultrasonic concentration meters have widely been used at water purification, sewage treatment and waste water treatment plants to sort and transfer high concentration sludges and to control the amount of chemical dosage. When an unusual substance is contained in the sludge, however, the attenuation of ultrasonic waves could be increased or not be transmitted to the receiver. In this case, the value measured by a concentration meter is higher than the actual density value or vibration. As well, it is difficult to automate the residuals treatment process according to the various problems such as sludge attachment or sensor failure. An ultrasonic multi-beam concentration sensor was considered to solve these problems, but an abnormal concentration value of a specific ultrasonic beam degrades the accuracy of the entire measurement in case of using a conventional arithmetic mean for all measurement values, so this paper proposes a method to improve the accuracy of the sludge concentration determination by choosing reliable sensor values and applying a neuro-fuzzy learning algorithm. The newly developed meter is proven to render useful results from a variety of experiments on a real water treatment plant. PMID:26512666

An Ultrasonic Multi-Beam Concentration Meter with a Neuro-Fuzzy Algorithm for Water Treatment Plants.

PubMed

Lee, Ho-Hyun; Jang, Sang-Bok; Shin, Gang-Wook; Hong, Sung-Taek; Lee, Dae-Jong; Chun, Myung Geun

2015-10-23

Ultrasonic concentration meters have widely been used at water purification, sewage treatment and waste water treatment plants to sort and transfer high concentration sludges and to control the amount of chemical dosage. When an unusual substance is contained in the sludge, however, the attenuation of ultrasonic waves could be increased or not be transmitted to the receiver. In this case, the value measured by a concentration meter is higher than the actual density value or vibration. As well, it is difficult to automate the residuals treatment process according to the various problems such as sludge attachment or sensor failure. An ultrasonic multi-beam concentration sensor was considered to solve these problems, but an abnormal concentration value of a specific ultrasonic beam degrades the accuracy of the entire measurement in case of using a conventional arithmetic mean for all measurement values, so this paper proposes a method to improve the accuracy of the sludge concentration determination by choosing reliable sensor values and applying a neuro-fuzzy learning algorithm. The newly developed meter is proven to render useful results from a variety of experiments on a real water treatment plant.

Sorption and oxic degradation of the explosive CL-20 during transport in subsurface sediments.

PubMed

Szecsody, J E; Girvin, D C; Devary, B J; Campbell, J A

2004-08-01

The abiotic sorption and oxic degradation processes that control the fate of the explosive CL-20, Hexanitrohexaazaisowurtzitane, in the subsurface environment were investigated to determine the potential for vadose and groundwater contamination. Sorption of aqueous CL-20 is relatively small (K(d) = 0.02-3.83 cm3 g(-1) for 7 sediments and 12 minerals), which results in only slight retardation relative to water movement. Thus, CL-20 could move quickly through unsaturated and saturated sediments of comparable composition to groundwater, similar to the subsurface behavior of RDX. CL-20 sorption was mainly to mineral surfaces of the sediments, and the resulting isotherm was nonlinear. CL-20 abiotically degrades in oxic environments at slow rates (i.e., 10s to 100s of hours) with a wide variety of minerals, but at fast rates (i.e., minutes) in the presence of 2:1 phyllosilicate clays (hectorite, montmorillonite, nontronite), micas (biotite, illite), and specific oxides (MnO2 and the ferrous-ferric iron oxide magnetite). High concentrations of surface ferrous iron in a dithionite reduced sediment degraded CL-20 the fastest (half-life < 0.05 h), but 2:1 clays containing no structural or adsorbed ferrous iron (hectorite) could also quickly degrade CL-20 (half-life < 0.2 h). CL-20 degradation rates were slower in natural sediments (half-life 3-800 h) compared to minerals. Sediments with slow degradation rates and small sorption would exhibit the highest potential for deep subsurface migration. Products of CL-20 oxic degradation included three high molecular weight compounds and anions (nitrite and formate). The 2-3.5 moles of nitrite produced suggest CL-20 nitro-groups are degraded, and the amount of formate produced (0.2-1.2 moles) suggests the CL-20 cage structure is broken in some sediments. Identification of further degradation products and CL-20 mineralization rates is needed to fully assess the impact of these CL-20 transformation rates on the risk of CL-20 (and degradation product) subsurface movement.

Characterization of an isoproturon mineralizing bacterial culture enriched from a French agricultural soil.

PubMed

Hussain, Sabir; Sørensen, Sebastian R; Devers-Lamrani, Marion; El-Sebai, Talaat; Martin-Laurent, Fabrice

2009-11-01

The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized by a bacterial culture isolated from an agricultural soil regularly exposed to IPU. Molecular analysis of the bacterial culture by DNA fingerprinting, cloning and sequencing of the 16S rRNA genes revealed that it consisted of six different members among whom the dominant was related to Sphingomonas sp. Six bacterial strains belonging to genera Ancylobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Variovorax and Agrobacterium were isolated from the IPU-degrading culture. None of these were able to degrade IPU in pure culture and only the intact culture sustained the ability to mineralize IPU. The composition of the culture appeared stable suggesting that yet unknown interactions are involved in the IPU mineralization. IPU degradation involved the transitory accumulation of three known IPU metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropylaniline and their further degradation. Thus, it indicates a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain. This culture did not degrade other structurally related phenylurea herbicides. The degrading activity of the bacterial culture was deeply influenced by the pH, being completely inhibited at pH 5.5 and optimal at pH 7.5.

Ultrasonic spray pyrolysis synthesis of reduced graphene oxide/anatase TiO2 composite and its application in the photocatalytic degradation of methylene blue in water.

PubMed

Park, Jeong-Ann; Yang, Boram; Lee, Joongki; Kim, In Gyeom; Kim, Jae-Hyun; Choi, Jae-Woo; Park, Hee-Deung; Nah, In Wook; Lee, Sang-Hyup

2018-01-01

Reduced graphene oxide (RGO)/anatase TiO 2 composite was prepared using a simple one-step technique-ultrasonic spray pyrolysis-in order to inhibit the aggregation of TiO 2 nanoparticles and to improve the photocatalytic performance for degradation of methylene blue (MB). Different proportions (0-5 wt%) of RGO/TiO 2 composites were characterized by scanning electronic microscopy (SEM), dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), Raman spectroscopy, UV-vis spectroscopy, and electrochemical impedance spectroscopy (EIS) to verify mechanism. From these analysis, TiO 2 nanoparticles are distributed uniformly on the RGO sheets with crumpled shape during ultrasonic spray pyrolysis and surface area is increasing by increasing portion of RGO. Band gap of RGO 5 /TiO 2 (5 wt% of RGO) composite is 2.72 eV and band gap was reduced by increasing portion of RGO in RGO/TiO 2 composites. The RGO 5 /TiO 2 composite was superior to other lower content of RGO/TiO 2 composites with a rapid transport of charge carriers and an effective charge separation. The highest removal efficiency of MB was obtained at the RGO 5 /TiO 2 composite under UVC irradiation, which coincided with the EIS, and the optimal dose of the composite was determined to be 0.5 g/L. The RGO 5 /TiO 2 composite improve the photocatalytic degradation rate of MB over the TiO 2 due to a retardation of electron-hole recombination. The MB adsorption capacity and photocatalytic degradation efficiency were greatly affected by pH changes and increased with increasing pH due to electrostatic interactions and generation of more hydroxyl radicals. The reusability of RGO 5 /TiO 2 composite was examined during 3 cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrasonic Data Display and Analysis System Developed (Including Fuzzy Logic Analysis) for the Windows-Based PC

NASA Technical Reports Server (NTRS)

Lovelace, Jeffrey J.; Cios, Kryzsztof J.; Roth, Don J.; cAO, wEI n.

2001-01-01

Post-Scan Interactive Data Display (PSIDD) III is a user-oriented Windows-based system that facilitates the display and comparison of ultrasonic contact measurement data obtained at NASA Glenn Research Center's Ultrasonic Nondestructive Evaluation measurement facility. The system is optimized to compare ultrasonic measurements made at different locations within a material or at different stages of material degradation. PSIDD III provides complete analysis of the primary waveforms in the time and frequency domains along with the calculation of several frequency-dependent properties including phase velocity and attenuation coefficient and several frequency-independent properties, like the cross correlation velocity. The system allows image generation on all the frequency-dependent properties at any available frequency (limited by the bandwidth used in the scans) and on any of the frequency-independent properties. From ultrasonic contact scans, areas of interest on an image can be studied with regard to underlying raw waveforms and derived ultrasonic properties by simply selecting the point on the image. The system offers various modes of indepth comparison between scan points. Up to five scan points can be selected for comparative analysis at once. The system was developed with Borland Delphi software (Visual Pascal) and is based on an SQL data base. It is ideal for the classification of material properties or the location of microstructure variations in materials. Along with the ultrasonic contact measurement software that it is partnered with, this system is technology ready and can be transferred to users worldwide.

Understanding nonlinear vibration behaviours in high-power ultrasonic surgical devices

PubMed Central

Mathieson, Andrew; Cardoni, Andrea; Cerisola, Niccolò; Lucas, Margaret

2015-01-01

Ultrasonic surgical devices are increasingly used in oral, craniofacial and maxillofacial surgery to cut mineralized tissue, offering the surgeon high accuracy with minimal risk to nerve and vessel tissue. Power ultrasonic devices operate in resonance, requiring their length to be a half-wavelength or multiple-half-wavelength. For bone surgery, devices based on a half-wavelength have seen considerable success, but longer multiple-half-wavelength endoscopic devices have recently been proposed to widen the range of surgeries. To provide context for these developments, some examples of surgical procedures and the associated designs of ultrasonic cutting tips are presented. However, multiple-half-wavelength components, typical of endoscopic devices, have greater potential to exhibit nonlinear dynamic behaviours that have a highly detrimental effect on device performance. Through experimental characterization of the dynamic behaviour of endoscopic devices, it is demonstrated how geometrical features influence nonlinear dynamic responses. Period doubling, a known route to chaotic behaviour, is shown to be significantly influenced by the cutting tip shape, whereas the cutting tip has only a limited effect on Duffing-like responses, particularly the shape of the hysteresis curve, which is important for device stability. These findings underpin design, aiming to pave the way for a new generation of ultrasonic endoscopic surgical devices. PMID:27547081

A pretreatment method for HPLC analysis of cypermethrin in microbial degradation systems.

PubMed

Liu, Shuliang; Yao, Kai; Jia, Dongying; Zhao, Nan; Lai, Wen; Yuan, Huaiyu

2012-07-01

In this paper, a pretreatment method for high-performance liquid chromatography (HPLC) determination of cypermethrin (CY) in microbial degradation systems was systemically studied, primarily to solve the problem of inaccurate determination of CY concentration caused by its uneven distribution in the systems. A suitable pretreatment method was established, including sampling, extraction and dehydration of CY. Partial sampling could be taken for bacterial and yeast systems in which CY was uniformly dispersed by an emulsifying agent, while total sampling was only suitable for mold systems with or without an emulsifying agent. CY could be fully extracted from the samples in which microbial cells were disrupted by ultrasonic treatment with acetonitrile under ultrasonic condition. The extract could be effectively dehydrated and purified by passing it through an anhydrous Na(2)SO(4) column followed by an elution with acetonitrile. The determination of CY in the pretreated sample by HPLC showed a high precision [relative standard deviation (RSD) = 1.14%, n = 5] and a good stability over a period of five days (RSD = 1.57%, n = 5). The recoveries of CY in microbial degradation systems at three different spiked levels ranged from 95.68 to 108.09% (RSD = 0.50-5.87%, n = 5).

Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites.

PubMed

Areerob, Yonrapach; Cho, Ju Yong; Jang, Won Kweon; Oh, Won-Chun

2018-03-01

Fe 3 O 4 -graphene/ZnO@mesoporous-SiO 2 (MGZ@SiO 2 ) nanocomposites was synthesized via a simple one pot hydrothermal method. The as-obtained samples were investigated using various techniques, as follows: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area (BET) vibrating sample magnetometer (VSM), among others. The sonocatalytic activities of the catalysts were tested according to the oxidation for the removal of methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultrasonic irradiation. The optimal conditions including the irradiation time, pH, dye concentration, catalyst dosage, and ultrasonic intensity are 60min, 11, 50mg/L, 1.00g/L, and 40W/m 2 , respectively. The MGZ@SiO 2 showed the higher enhanced sonocatalytic degradation from among the three dyes; furthermore, the sonocatalytic-degradation mechanism is discussed. This study shows that the MGZ@SiO 2 can be applied asa novel-design catalyst for the removal of organic pollutants from aqueous solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Testosterone-mineralizing culture enriched from swine manure: characterization of degradation pathways and microbial community composition.

PubMed

Yang, Yun-Ya; Pereyra, Luciana P; Young, Robert B; Reardon, Kenneth F; Borch, Thomas

2011-08-15

Environmental releases and fate of steroid sex hormones from livestock and wastewater treatment plants are of increasing regulatory concern. Despite the detection of these hormones in manures, biosolids, and the environment, little attention has been paid to characterization of fecal bacteria capable of hormone degradation. The enrichments of (swine) manure-borne bacteria capable of aerobic testosterone degradation were prepared and the testosterone mineralization pathway was elucidated. Six DNA sequences of bacteria from the Proteobacteria phylum distributed among the genera Acinetobacter, Brevundimonas, Comamonas, Sphingomonas, Stenotrophomonas, and Rhodobacter were identified in a testosterone-degrading enriched culture with testosterone as the sole carbon source. Three degradation products of testosterone were identified as androstenedione, androstadienedione, and dehydrotestosterone using commercially available reference standards, liquid chromatography-UV diode array detection, and liquid chromatography-time-of-flight mass spectrometry (LC-TOF/MS). Three additional degradation products of testosterone were tentatively identified as 9α-hydroxytestosterone, 9α-hydroxyandrostadienedione or 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione, and 9α-hydroxydehydrotestosterone or 9α-hydroxyandrostenedione using LC-TOF/MS. When (14)C-testosterone was introduced to the enriched culture, 49-68% of the added (14)C-testosterone was mineralized to (14)CO(2) within 8 days of incubation. The mineralization of (14)C-testosterone followed pseudo-first-order reaction kinetics in the enriched culture with half-lives (t(1/2)) of 10-143 h. This work suggests that Proteobacteria play an important environmental role in degradation of steroid sex hormones and that androgens have the potential to be mineralized during aerobic manure treatment or after land application to agricultural fields by manure-borne bacteria.

MICROCOSM STUDY OF DEGRADATION OF CHLORINATED SOLVENTS ON SYNTHETIC GREEN RUST MINERALS

EPA Science Inventory

Green rust minerals contain ferrous ion in their structure that can potentially serve as a chemical reductant for degradation of chlorinated solvents. Green rusts are found in zerovalent iron based permeable reactive barriers and in certain soil and sediments. Some previous labor...

Model-Based IN SITU Parameter Estimation of Ultrasonic Guided Waves in AN Isotropic Plate

NASA Astrophysics Data System (ADS)

Hall, James S.; Michaels, Jennifer E.

2010-02-01

Most ultrasonic systems employing guided waves for flaw detection require information such as dispersion curves, transducer locations, and expected propagation loss. Degraded system performance may result if assumed parameter values do not accurately reflect the actual environment. By characterizing the propagating environment in situ at the time of test, potentially erroneous a priori estimates are avoided and performance of ultrasonic guided wave systems can be improved. A four-part model-based algorithm is described in the context of previous work that estimates model parameters whereby an assumed propagation model is used to describe the received signals. This approach builds upon previous work by demonstrating the ability to estimate parameters for the case of single mode propagation. Performance is demonstrated on signals obtained from theoretical dispersion curves, finite element modeling, and experimental data.

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

PubMed

Nasser, A; Mingelgrin, U

2014-07-01

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

Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

PubMed

Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

2015-07-01

Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

Enhanced degradation and mineralization of 4-chloro-3-methyl phenol by Zn-CNTs/O3 system.

PubMed

Liu, Yong; Zhou, Anlan; Liu, Yanlan; Wang, Jianlong

2018-01-01

A novel zinc-carbon nanotubes (Zn-CNTs) composite was prepared, characterized and used in O 3 system for the enhanced degradation and mineralization of chlorinated phenol. The Zn-CNTs was characterized by SEM, BET and XRD, and the degradation of 4-chloro-3-methyl phenol (CMP) in aqueous solution was investigated using Zn-CNTs/O 3 system. The experimental results showed that the rate constant of total organic carbon (TOC) removal was 0.29 min -1 , much higher than that of only O 3 system (0.059 min -1 ) because Zn-CNTs/O 2 system could generate H 2 O 2 in situ, the concentration of H 2 O 2 could reach 156.14 mg/L within 60 min at pH 6.0. The high mineralization ratio of CMP by Zn-CNTs/O 3 occurred at wide pH range (3.0-9.0). The increase of Zn-CNTs dosage or gas flow rate contributed to the enhancement of CMP mineralization. The intermediates of CMP degradation were identified and the possible degradation pathway was tentatively proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation

PubMed Central

Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

2015-01-01

Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant ‘seed bank'. PMID:25535940

Propham mineralization in aqueous medium by anodic oxidation using boron-doped diamond anode: influence of experimental parameters on degradation kinetics and mineralization efficiency.

PubMed

Ozcan, Ali; Sahin, Yücel; Koparal, A Savaş; Oturan, Mehmet A

2008-06-01

This study aims the removal of a carbamate herbicide, propham, from aqueous solution by direct electrochemical advanced oxidation process using a boron-doped diamond (BDD) anode. This electrode produces large quantities of hydroxyl radicals from oxidation of water, which leads to the oxidative degradation of propham up to its total mineralization. Effect of operational parameters such as current, temperature, pH and supporting electrolyte on the degradation and mineralization rate was studied. The applied current and temperature exert a prominent effect on the total organic carbon (TOC) removal rate of the solutions. The mineralization of propham can be performed at any pH value between 3 and 11 without any loss in oxidation efficiency. The propham decay and its overall mineralization reaction follows a pseudo-first-order kinetics. The apparent rate constant value of propham oxidation was determined as 4.8 x 10(-4)s(-1) at 100 mA and 35 degrees C in the presence of 50mM Na(2)SO(4) in acidic media (pH: 3). A general mineralization sequence was proposed considering the identified oxidation intermediates.

Optimisation of chemical oxygen demand removal from landfill leachate by sonocatalytic degradation in the presence of cupric oxide nanoparticles.

PubMed

Amirian, Paria; Bazrafshan, Edris; Payandeh, Abolfazl

2017-06-01

Leachate is the liquid formed when waste breaks down in the landfill and water filters through that waste. This liquid is very toxic and can pollute the land, ground water, and water resources. In most countries, it is mandatory for landfills to be protected against leachate. In addition to all other harms to the environment, disposal of raw landfill leachate can be a major source of hazard to closed water bodies. Hence, treatment of landfill leachate is considered an essential step prior to its discharge from source. This article describes the sonocatalytic degradation of chemical oxygen demand in landfill leachate using cupric oxide nanoparticles as sonocatalyst (cupric oxide/ultrasonic) and aims to establish this method as an effective alternative to currently used approaches. An ideal experimental design was carried out based on a central composite design with response surface methodology. The response surface methodology was used to evaluate the effect of process variables including pH values (3, 7, 11), cupric oxide nanoparticles dose (0.02, 0.035, 0.05 g), reaction time (10, 35, 60 minutes), ultrasonic frequency (35, 37, 130 KHz), and their interaction towards the attainment of their optimum conditions. The derived second-order model, including both significant linear and quadratic terms, seemed to be adequate in predicting responses (R 2  = 0.9684 and prediction R 2  = 0.9581). The optimum conditions for the maximum chemical oxygen demand sonocatalytic degradation of 85.82% were found to be pH 6.9, cupric oxide nanoparticles dosage of 0.05 gr L -1 , and the ultrasonic frequency of 130 kHz at a contact time of 10 min.

Bacterial Production and Contamination Mineralization in Sediments of the Ala Wai Canal, Oahu, Hawaii

DTIC Science & Technology

2009-09-29

fluoranthene (45 mCi mmol-1), and 9-14C- phenanthrene (55 mCi mmol-1) (Sigma Chemical), as well as the lignin degradation intermediate, UL-14C- catechol...intermediate involved in lignin degradation and areas where lignin and other more refractory materials are being metabolized may have more rapid mineralization...indicating much of the lignin -derived organic matter is likely from nonwoody tissue (Figure 25). Lignin degradation in sediment has been measured

Diffused sunlight driven highly synergistic pathway for complete mineralization of organic contaminants using reduced graphene oxide supported photocatalyst.

PubMed

Babu, Sundaram Ganesh; Ramalingam Vinoth; Neppolian, Bernaurdshaw; Dionysiou, Dionysios D; Ashokkumar, Muthupandian

2015-06-30

Diffused sunlight is found to be an effective light source for the efficient degradation and mineralization of organic pollutant (methyl orange as a probe) by sono-photocatalytic degradation using reduced graphene oxide (rGO) supported CuO-TiO2 photocatalyst. The prepared catalysts are characterized by XRD, XPS, UV-vis DRS, PL, photoelectrochemical, SEM-EDS and TEM. A 10 fold synergy is achieved for the first time by combining sonochemical and photocatalytic degradation under diffused sunlight. rGO loading augments the activity of bare CuO-TiO2 more than two fold. The ability of rGO in storing, transferring, and shuttling electrons at the heterojunction between TiO2 and CuO facilitates the separation of photogenerated electron-hole pairs, as evidenced by the photoluminescence results. The complete mineralization of MO and the by-products within a short span of time is confirmed by TOC analysis. Further, hydroxyl radical mediated degradation under diffused sunlight is confirmed by LC-MS. This system shows similar activity for the degradation of methylene blue and 4-chlorophenol indicating the versatility of the catalyst for the degradation of various pollutants. This investigation is likely to open new possibilities for the development of highly efficient diffused sunlight driven TiO2 based photocatalysts for the complete mineralization of organic contaminants. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation of anti-inflammatory drug ketoprofen by electro-oxidation: comparison of electro-Fenton and anodic oxidation processes.

PubMed

Feng, Ling; Oturan, Nihal; van Hullebusch, Eric D; Esposito, Giovanni; Oturan, Mehmet A

2014-01-01

The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8 ± 0.1) × 10(9) M(-1) s(-1) by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.

Direct Determination of Molecular Weight Distribution of Calf-Thymus DNAs and Study of Their Fragmentation under Ultrasonic and Low-Energy IR Irradiations. A Charge Detection Mass Spectrometry Investigation.

PubMed

Halim, Mohammad A; Bertorelle, Franck; Doussineau, Tristan; Antoine, Rodolphe

2018-06-09

Calf-thymus (CT-DNA) is widely used as binding agent. The commercial samples are known to be "highly polymerized DNA" samples. CT-DNA is known to be fragile in particular upon ultrasonic wave irradiation. Degradation products might have dramatic consequence on its bio-sensing activity, and an accurate determination of the molecular weight distribution and stability of commercial samples is highly demanded. We investigated the sensitivity of charge detection mass spectrometry (CDMS), a single-molecule MS method, both with single-pass and ion trap CDMS ("Benner" trap) modes to the determination of the composition and stability (under multiphoton IR irradiation) of calf-thymus DNAs. We also investigated the changes of molecular weight distributions in the course of sonication by irradiating ultrasonic wave to CT-DNA. We report for the first time, the direct molecular weight (MW) distribution of DNA sodium salt from calf-thymus revealing two populations at high (~10 MDa) and low (~3 MDa) molecular weights. We evidence a transition between the high-MW to the low-MW distribution, confirming that the low-MW distribution results from degradation of CT-DNA. Finally, we report also IRMPD experiments carried out on trapped single-stranded linear DNAs from calf-thymus allowing to extract their activation energy for unimolecular dissociation. We show that single-pass CDMS is a direct, efficient and accurate MS-based approach to determine the composition of calf-thymus DNAs. Furthermore, ion trap CDMS allows us to evaluate the stability (both under multiphoton IR irradiation and in the course of sonication by irradiating ultrasonic wave) of calf-thymus DNAs. This article is protected by copyright. All rights reserved.

Ultrasound promoted reaction of Rhodamine B with sodium hypochlorite using sonochemical and dental ultrasonic instruments.

PubMed

Tiong, T Joyce; Price, Gareth J

2012-03-01

The sonochemical acceleration of bleaching of Rhodamine B by sodium hypochlorite has been studied using ultrasound intensities in the range 0-7 W cm(-2). Using a 20 kHz ultrasonic horn, it was shown that ultrasound could significantly shorten the treatment time and/or the concentration of hypochlorite required for the reaction. A number of intermediate species formed during the reaction have been identified. It was demonstrated that the same sonochemical reactions occur during the use of dental ultrasound instruments of the type used in endodontics where hypochlorite solutions act as disinfectants. Results showed pseudo-first order degradation kinetics for the degradation of Rhodamine B for both types of source. Both the distribution of cavitation and the resulting bleaching reactions were dependent on the design of the tips. The bleaching reaction can therefore be used to characterise the behaviour of dental instruments and aid in the optimisation of their performance. Copyright © 2011 Elsevier B.V. All rights reserved.

Ultrasound-assisted extraction of water-soluble polysaccharides from the roots of valerian (Valeriana officinalis L.).

PubMed

Hromádková, Z; Ebringerová, A; Valachovic, P

2002-01-01

The insoluble plant residues, obtained after preparation of medicinal tinctures from the roots of valerian (Valeriana officinalis L.) by classical and ultrasound-assisted extraction with aqueous ethanol in a pilot plant, were subsequently treated with hot water to isolate the accessible polysaccharide cell wall components. At almost equal amounts of the hot-water extractable material, the yields of the recovered polysaccharides were lower in the ultrasonical experiment. This is due to the fact that a part of accessible polysaccharides were already solubilised by the aqueous ethanol and recoverable from the medicinal tincture. Therefore, the net yield of extracted polysaccharides was enhanced in the ultrasonical procedure. This fact as well as the sugar composition and structural features of the isolated polysaccharides suggest that ultrasonication have attacked the integrity of cell walls, released and degraded its most accessible polysaccharides (pectic polysaccharides and starch) and increased also the extractibility of its less accessible components--xylan, mannan and glucan. The water-soluble polysaccharide fractions from both the conventional and ultrasonical experiments exhibit significant immunostimulatory activities in mitogenic and comitogenic thymocyte tests.

Interfacial interaction between methyl parathion-degrading bacteria and minerals is important in biodegradation.

PubMed

Zhao, Gang; Huang, Qiaoyun; Rong, Xingmin; Cai, Peng; Liang, Wei; Dai, Ke

2014-02-01

In the present study, the influence of kaolinite and goethite on microbial degradation of methyl parathion was investigated. We observed that the biodegradation process was improved by kaolinite and depressed by goethite. Calorimetric data further showed that the metabolic activities of degrading cells (Pseudomonas putida) were enhanced by the presence of kaolinite and depressed by the presence of goethite. A semipermeable membrane experiment was performed and results supported the above observations: the promotive effect of kaolinite and the inhibition of goethite for microbial degradation was not found when the bacteria was enclosed by semipermeable membrane and had no direct contact with these minerals, suggesting the important function of the contact of cellular surfaces with mineral particles. The relative larger particles of kaolinite were loosely attached to the bacteria. This attachment made the cells easy to use the sorbed substrate and then stimulated biodegradation. For goethite, small particles were tightly bound to bacterial cells and limited the acquisition of substrate and nutrients, thereby inhibiting biodegradation. These results indicated that interfacial interaction between bacterial cells and minerals significantly affected the biodegradation of pesticides.

An ammonium sulfate/ethanol aqueous two-phase system combined with ultrasonication for the separation and purification of lithospermic acid B from Salvia miltiorrhiza Bunge.

PubMed

Guo, Y X; Han, J; Zhang, D Y; Wang, L H; Zhou, L L

2012-07-01

We studied the effect of ultrasonication extraction technology combined with ammonium sulfate/ethanol aqueous two-phase system (ATPS) for the separation of lithospermic acid B (LAB) from Salvia miltiorrhiza Bunge. According to the literature and preliminary studies, ammonium sulfate concentration, ethanol concentration, pH, ultrasonication power, ultrasonication time and the ratio of solvent-to-solid were investigated using a single factor design to identify the factors affecting separation. Taking into consideration a simultaneous increase in LAB recovery (R (%)) and partition coefficient (K), the best performance of the ATPS was obtained at 25°C and pH 2 using ammonium sulfate 22% (w/w) and ethanol 30% (w/w). To keep the solvent-to-solid ratio at 10, response surface methodology was used to find the optimal ultrasonication power and ultrasonication time. Quadratic models were predicted for LAB yield in the upper phase. Optimal conditions of 572.1 W ultrasonication power and 42.2 min produced a maximum yield of LAB of 42.16 mg g(-1) sample. There was no obvious degradation of LAB with ultrasound under the applied conditions, and the experimental yield of LAB was 42.49 mg g(-1) sample and the purity was 55.28% (w/w), which was much higher than that obtained using conventional extraction. The present study demonstrated that ultrasound coupled with aqueous two-phase systems is very efficient tool for the extraction and purification of LAB from Salvia miltiorrhiza Bunge. Copyright © 2011 Elsevier B.V. All rights reserved.

PSIDD3: Post-Scan Ultrasonic Data Display System for the Windows-Based PC Including Fuzzy Logic Analysis

NASA Technical Reports Server (NTRS)

Lovelace, Jeffrey J.; Cios, Krzysztof J.; Roth, Don J.; Cao, Wei

2000-01-01

Post-Scan Interactive Data Display (PSIDD) III is a user-oriented Windows-based system that facilitates the display and comparison of ultrasonic contact data. The system is optimized to compare ultrasonic measurements made at different locations within a material or at different stages of material degradation. PSIDD III provides complete analysis of the primary wave forms in the time and frequency domains along with the calculation of several frequency dependent properties including Phase Velocity and Attenuation Coefficient and several frequency independent properties, like the Cross Correlation Velocity. The system allows image generation on all of the frequency dependent properties at any available frequency (limited by the bandwidth used in the scans) and on any of the frequency independent properties. From ultrasonic contact scans, areas of interest on an image can be studied with regard to underlying raw waveforms and derived ultrasonic properties by simply selecting the point on the image. The system offers various modes of in-depth comparison between scan points. Up to five scan points can be selected for comparative analysis at once. The system was developed with Borland Delphi software (Visual Pascal) and is based on a SQL database. It is ideal for classification of material properties, or location of microstructure variations in materials.

Ultrasound-modulated optical tomography with intense acoustic bursts.

PubMed

Zemp, Roger J; Kim, Chulhong; Wang, Lihong V

2007-04-01

Ultrasound-modulated optical tomography (UOT) detects ultrasonically modulated light to spatially localize multiply scattered photons in turbid media with the ultimate goal of imaging the optical properties in living subjects. A principal challenge of the technique is weak modulated signal strength. We discuss ways to push the limits of signal enhancement with intense acoustic bursts while conforming to optical and ultrasonic safety standards. A CCD-based speckle-contrast detection scheme is used to detect acoustically modulated light by measuring changes in speckle statistics between ultrasound-on and ultrasound-off states. The CCD image capture is synchronized with the ultrasound burst pulse sequence. Transient acoustic radiation force, a consequence of bursts, is seen to produce slight signal enhancement over pure ultrasonic-modulation mechanisms for bursts and CCD exposure times of the order of milliseconds. However, acoustic radiation-force-induced shear waves are launched away from the acoustic sample volume, which degrade UOT spatial resolution. By time gating the CCD camera to capture modulated light before radiation force has an opportunity to accumulate significant tissue displacement, we reduce the effects of shear-wave image degradation, while enabling very high signal-to-noise ratios. Additionally, we maintain high-resolution images representative of optical and not mechanical contrast. Signal-to-noise levels are sufficiently high so as to enable acquisition of 2D images of phantoms with one acoustic burst per pixel.

Echodentography based on nonlinear time reversal tomography: Ultrasonic nonlinear signature identification

NASA Astrophysics Data System (ADS)

Santos, Serge Dos; Farova, Zuzana; Kus, Vaclav; Prevorovsky, Zdenek

2012-05-01

This paper examines possibilities of using Nonlinear Elastic Wave Spectroscopy (NEWS) methods in dental investigations. Themain task consisted in imaging cracks or other degradation signatures located in dentin close to the Enamel-Dentine Junction (EDJ). NEWS approach was investigated experimentally with a new bi-modal acousto-optic set-up based on the chirp-coded nonlinear ultrasonic time reversal (TR) concepts. Complex internal structure of the tooth is analyzed by the TR-NEWS procedure adapted to tomography-like imaging of the tooth damages. Ultrasonic instrumentation with 10 MHz bandwidth has been set together including laser vibrometer used to detect responses of the tooth on its excitation carried out by a contact piezoelectric transducer. Bi-modal TR-NEWS images of the tooth were created before and after focusing, which resulted from the time compression. The polar B-scan of the tooth realized with TR-NEWS procedure is suggested to be applied as a new echodentography imaging.

Influence of ultrasonication on anaerobic bioconversion of sludge.

PubMed

Mao, Taohong; Show, Kuan-Yeow

2007-04-01

The influence of ultrasonication on hydrolysis, acidogenesis, and methanogenesis in anaerobic decomposition of sludge was investigated. The sonicated sludge exhibited prehydrolysis and preacidogenesis effects in the anaerobic decomposition process. First-order hydrolysis rates increased from 0.0384 day(-1) in the control digester to 0.0672 day(-1) in the digester fed, with sludge sonicated at 0.52 W/mL. The sonication appeared to be ineffective in relation to acidogenesis reaction rates, but it provided a better buffering capacity to diminish the adverse effect of acidification. Digesters fed with sonicated sludge demonstrated enhanced methanogenesis over the control unit. Determination by coenzyme F420 verified that sonication is able to promote the growth of methanogenic biomass and facilitate a positive methanogenic microbial development in suppressing the initial methanogenesis limitation. The results suggest that ultrasonication could enhance anaerobic decomposition of sludge, resulting in an accelerated bioconversion, improved organics degradation, improved biogas production, and increased methane content.

Accelerated biodegradation of selected nematicides in tropical crop soils from Costa Rica.

PubMed

Chin-Pampillo, Juan Salvador; Carazo-Rojas, Elizabeth; Pérez-Rojas, Greivin; Castro-Gutiérrez, Víctor; Rodríguez-Rodríguez, Carlos E

2015-01-01

Degradation and mineralization behavior of selected nematicides was studied in soil samples from fields cultivated with banana, potato, and coffee. Degradation assays in most of the studied soils revealed shorter half-lives for carbofuran (CBF) and ethoprophos (ETP) in samples with a history of treatment with these compounds, which may have been caused by enhanced biodegradation. A short half-life value for CBF degradation was also observed in a banana field with no previous exposure to this pesticide, but with a recent application of the carbamate insecticide oxamyl, which supports the hypothesis that preexposure to oxamyl may cause microbial adaptation towards degradation of CBF, an observation of a phenomenon not yet tested according to the literature reviewed. Mineralization assays for CBF and terbufos (TBF) revealed that history of treatment with these nematicides did not cause higher mineralization rates in preexposed soils when compared to unexposed ones, except in the case of soils from coffee fields. Mineralization half-lives for soils unexposed to these pesticides were significantly shorter than most reports in the literature in the same conditions. Mineralization rates for soils with a previous exposure to these pesticides were also obtained, adding to the very few reports found. This paper contributes valuable data to the low number of reports dealing with pesticide fate in soils from tropical origin.

Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment

NASA Astrophysics Data System (ADS)

Brüchert, Volker; Bröder, Lisa; Sawicka, Joanna E.; Tesi, Tommaso; Joye, Samantha P.; Sun, Xiaole; Semiletov, Igor P.; Samarkin, Vladimir A.

2018-01-01

The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organic-carbon-rich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O2 microelectrode profiling; intact sediment core incubations; 35S-sulfate tracer experiments; pore-water dissolved inorganic carbon (DIC); δ13CDIC; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84 % of the depth-integrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC / NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual end-member calculations, the terrestrial organic carbon contribution varied between 32 and 36 %, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope end-member apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr-1 is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3 Tg C yr-1 is degraded by anaerobic processes, with a terrestrial organic carbon contribution ranging between 0.3 and 0.5 Tg yr-1.

Enhanced degradation of isoproturon in an agricultural soil by a Sphingomonas sp. strain and a microbial consortium.

PubMed

Li, Renyi; Dörfler, Ulrike; Munch, Jean Charles; Schroll, Reiner

2017-02-01

Isoproturon (IPU) degradation in an agricultural soil inoculated with an isolated IPU-degrader strain (Sphingomonas sp. strain AK1, IS) or a microbial consortium (MC) harboring this strain, with or without carrier material, were investigated in soil microcosm experiments during 46 days. Effect of the carrier material and inoculation size on IPU-degradation efficacy of the inoculants were studied. Mineralization, extractable residues and non-extractable residues of 14 C-labeled IPU were analyzed. The low IPU mineralization in untreated soil (7.0%) was enhanced to different extents by inoculation of IS (17.4%-46.0%) or MC (58.9%-67.5%). Concentrations of IPU residues in soils amended with MC (0.002-0.095 μg g dry soil -1 ) were significantly lower than in soils amended with IS (0.02-0.67 μg g dry soil -1 ) and approximately 10 times lower than in the uninoculated soil (0.06-0.80 μg g dry soil -1 ). Less extractable residues and non-extractable residues were detected in soil with higher IPU mineralization. Inoculation size (as indicated by the volume of liquid cultures or by the number of carrier particles) determined the IPU-removal efficacy of IS in soil, but this effect was less pronounced for MC. The low sorption of IPU to soil and the decreasing IPU-mineralizing rates suggested incapability of IS to establish the IPU-mineralizing function in the soil. The thorough removal of IPU and persistent IPU-mineralizing activity of soil inoculated with MC indicated a high persistence of IPU-metabolic trait. Our results showed that microbial consortia might be more efficient than single degrader strains to enhance clean-up of organic chemicals in soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Robust Linuron Degradation in On-Farm Biopurification Systems Exposed to Sequential Environmental Changes▿

PubMed Central

Sniegowski, Kristel; Bers, Karolien; Ryckeboer, Jaak; Jaeken, Peter; Spanoghe, Pieter; Springael, Dirk

2011-01-01

On-farm biopurification systems (BPS) treat pesticide-contaminated wastewater of farms through biodegradation. Adding pesticide-primed soil has been shown to be beneficial for the establishment of pesticide-degrading populations in BPS. However, no data exist on the response of pesticide-degrading microbiota, either endogenous or introduced with pesticide-primed soil, when BPS are exposed to expected less favorable environmental conditions like cold periods, drought periods, and periods without a pesticide supply. Therefore, the response of microbiota mineralizing the herbicide linuron in BPS microcosm setups inoculated either with a linuron-primed soil or a nonprimed soil to a sequence of such less favorable conditions was examined. A period without linuron supply or a drought period reduced the size of the linuron-mineralizing community in both setups. The most severe effect was recorded for the setup containing nonprimed soil, in which stopping the linuron supply decreased the linuron degradation capacity to nondetectable levels. In both systems, linuron mineralization rapidly reestablished after conventional operation conditions were restored. A cold period and feeding with a pesticide mixture did not affect linuron mineralization. The changes in the linuron-mineralizing capacity in microcosms containing primed soil were associated with the dynamics of a particular Variovorax phylotype that previously had been associated with linuron mineralization. This study suggests that the pesticide-mineralizing community in BPS is robust in stress situations imposed by changes in environmental conditions expected to occur on farms. Moreover, it suggests that, in cases where effects do occur, recovery is rapid after restoring conventional operation conditions. PMID:21803897

Degradation and mineralization of chitin in an estuary

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

Boyer, J.

1987-01-01

A method for measuring microbial degradation and mineralization of radiolabeled native chitin is described. /sup 14/C-labeled chitin was synthesized in vivo by injecting shed blue crabs (Callinectes sapidus) with N-acetyl-D-(/sup 14/C)-glucosamine, allowing for its incorporation into the exoskeleton. Rates of chitin degradation and mineralization in estuarine water and sediments were determined as functions of temperature, inoculum source, and oxygen condition. Significant differences in rates between temperature treatments were evident. Q/sub 10/ values ranged from 1.2 to 2.5 for water and sediment, respectively. Increased incubation temperature also resulted in decreased lag times before onset of chitinoclastic bacterial growth and chitin degradation.more » The anaerobic pathway of chitin decomposition by chitinoclastic bacteria was examined with an emphasis on end product coupling to other bacterial types. Actively growing chitinoclastic bacterial isolates produced primarily acetate, hydrogen, and carbon dioxide in broth culture.« less

Photodegradation of Acid Violet 7 with AgBr-ZnO under highly alkaline conditions.

PubMed

Krishnakumar, B; Swaminathan, M

2012-12-01

The photocatalytic activity of AgBr-ZnO was investigated for the degradation of Acid Violet 7 (AV 7) in aqueous solution using UV-A light. AgBr-ZnO is found to be more efficient than commercial ZnO and prepared ZnO at pH 12 for the mineralization of AV 7. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization have been analyzed. Expect oxone, other oxidants decrease the degradation efficiency. Addition of metal ions and anions decrease the degradation efficiency of AgBr-ZnO significantly. The mineralization of AV 7 has also been confirmed by COD measurements. The mechanism of degradation by AgBr-ZnO is proposed to explain its higher activity under UV light. The catalyst is found to be reusable. Copyright © 2012 Elsevier B.V. All rights reserved.

Substantially enhanced degradation of hexachlorocyclohexane isomers by a microbial consortium on acclimation.

PubMed

Elcey, C Daniel; Kunhi, A A Mohammad

2010-01-27

Widespread contamination of the environment, globally, has been caused by extensive and indiscriminate use of hexachlorocyclohexane (HCH) as an insecticide since the 1940s, threatening the biota including humans, and there is an urgent need to eliminate it, preferably through bioremediation technologies. A gamma-HCH-degrading microbial consortium was isolated by enrichment of a soil sample from a sugar cane field having a long history of technical grade HCH application. On acclimation the degrading ability improved substantially. The consortium, which took 10 days to degrade 25 microg mL(-1) of gamma-HCH, initially could mineralize even 300 microg mL(-1) of the substrate within 108 h on acclimation. With 300 microg mL(-1) substrate, the rate of degradation, as calculated for the early exponential phase, was 216 microg mL(-1) day(-1), the highest reported so far. An amount of 400 microg mL(-1) of gamma-HCH, however, was mineralized partially with only 78% Cl(-) release. No apparent accumulation of intermediary metabolites was observed up to 300 microg mL(-1) substrate, indicating a fast rate of mineralization. Aeration, mesophilic temperatures (20-35 degrees C), and near neutral pH (6.0-8.0) were favorable conditions for degradation. The presence of glucose at 1000 microg mL(-1) retarded the degradation, whereas cellulose and sawdust at 1600 microg mL(-1) and glucose at 100 microg mL(-1) did not show any marked effect. The consortium also mineralized alpha-, beta-, and delta-HCH efficiently. The consortium consisted of nine bacterial strains and a fungal strain, and individually they were able to degrade 10 microg mL(-1) of gamma-HCH. This mixed culture holds high potential for deployment in bioremediation of HCH-contaminated soils, waste dumpsites, and water bodies.

Degradation of trimethoprim by gamma irradiation in the presence of persulfate

NASA Astrophysics Data System (ADS)

Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

2016-10-01

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

Differential regulation of phenanthrene biodegradation process by kaolinite and quartz and the underlying mechanism.

PubMed

Gong, Beini; Wu, Pingxiao; Ruan, Bo; Zhang, Yating; Lai, Xiaolin; Yu, Langfeng; Li, Yongtao; Dang, Zhi

2018-05-05

Natural and cost-effective materials such as minerals can serve as supportive matrices to enhance biodegradation of polycyclic aromatic hydrocarbons (PAHs). In this study we evaluated and compared the regulatory role of two common soil minerals, i.e. kaolinite and quartz in phenanthrene (a model PAH) degradation by a PAH degrader Sphingomonas sp. GY2B and investigated the underlying mechanism. Overall kaolinite was more effective than quartz in promoting phenanthrene degradation and bacterial growth. And it was revealed that a more intimate association was established between GY2B and kaolinite. Si and O atoms on mineral surface were demonstrated to be involved in GY2B-mineral interaction. There was an higher polysaccharide/lipid content in the EPS (extracellular polymeric substances) secreted by GY2B on kaolinite than on quartz. Altogether, these results showed that differential bacterial growth, enzymatic activity, EPS composition as well as the interface interaction may explain the effects minerals have on PAH biodegradation. It was implicated that different interface interaction between different minerals and bacteria can affect microbial behavior, which ultimately results in different biodegradation efficiency. Copyright © 2018 Elsevier B.V. All rights reserved.

Processing of ultra-high molecular weight polyethylene/graphite composites by ultrasonic injection moulding: Taguchi optimization.

PubMed

Sánchez-Sánchez, Xavier; Elias-Zuñiga, Alex; Hernández-Avila, Marcelo

2018-06-01

Ultrasonic injection moulding was confirmed as an efficient processing technique for manufacturing ultra-high molecular weight polyethylene (UHMWPE)/graphite composites. Graphite contents of 1 wt%, 5 wt%, and 7 wt% were mechanically pre-mixed with UHMWPE powder, and each mixture was pressed at 135 °C. A precise quantity of the pre-composites mixtures cut into irregularly shaped small pieces were subjected to ultrasonic injection moulding to fabricate small tensile specimens. The Taguchi method was applied to achieve the optimal level of ultrasonic moulding parameters and to maximize the tensile strength of the composites; the results showed that mould temperature was the most significant parameter, followed by the graphite content and the plunger profile. The observed improvement in tensile strength in the specimen with 1 wt% graphite was of 8.8% and all composites showed an increase in the tensile modulus. Even though the presence of graphite produced a decrease in the crystallinity of all the samples, their thermal stability was considerably higher than that of pure UHMWPE. X-ray diffraction and scanning electron microscopy confirmed the exfoliation and dispersion of the graphite as a function of the ultrasonic processing. Fourier transform infrared spectra showed that the addition of graphite did not influence the molecular structure of the polymer matrix. Further, the ultrasonic energy led oxidative degradation and chain scission in the polymer. Copyright © 2018 Elsevier B.V. All rights reserved.

High Piezo-photocatalytic Efficiency of CuS/ZnO Nanowires Using Both Solar and Mechanical Energy for Degrading Organic Dye.

PubMed

Hong, Deyi; Zang, Weili; Guo, Xiao; Fu, Yongming; He, Haoxuan; Sun, Jing; Xing, Lili; Liu, Baodan; Xue, Xinyu

2016-08-24

High piezo-photocatalytic efficiency of degrading organic pollutants has been realized from CuS/ZnO nanowires using both solar and mechanical energy. CuS/ZnO heterostructured nanowire arrays are compactly/vertically aligned on stainless steel mesh by a simple two-step wet-chemical method. The mesh-supported nanocomposites can facilitate an efficient light harvesting due to the large surface area and can also be easily removed from the treated solution. Under both solar and ultrasonic irradiation, CuS/ZnO nanowires can rapidly degrade methylene blue (MB) in aqueous solution, and the recyclability is investigated. In this process, the ultrasonic assistance can greatly enhance the photocatalytic activity. Such a performance can be attributed to the coupling of the built-in electric field of heterostructures and the piezoelectric field of ZnO nanowires. The built-in electric field of the heterostructure can effectively separate the photogenerated electrons/holes and facilitate the carrier transportation. The CuS component can improve the visible light utilization. The piezoelectric field created by ZnO nanowires can further separate the photogenerated electrons/holes through driving them to migrate along opposite directions. The present results demonstrate a new water-pollution solution in green technologies for the environmental remediation at the industrial level.

Bioavailability of minerals in legumes.

PubMed

Sandberg, Ann-Sofie

2002-12-01

The mineral content of legumes is generally high, but the bioavailability is poor due to the presence of phytate, which is a main inhibitor of Fe and Zn absorption. Some legumes also contain considerable amounts of Fe-binding polyphenols inhibiting Fe absorption. Furthermore, soya protein per se has an inhibiting effect on Fe absorption. Efficient removal of phytate, and probably also polyphenols, can be obtained by enzymatic degradation during food processing, either by increasing the activity of the naturally occurring plant phytases and polyphenol degrading enzymes, or by addition of enzyme preparations. Biological food processing techniques that increase the activity of the native enzymes are soaking, germination, hydrothermal treatment and fermentation. Food processing can be optimized towards highest phytate degradation provided that the optimal conditions for phytase activity in the plant is known. In contrast to cereals, some legumes have highest phytate degradation at neutral or alkaline pH. Addition of microbial enzyme preparations seems to be the most efficient for complete degradation during processing. Fe and Zn absorption have been shown to be low from legume-based diets. It has also been demonstrated that nutritional Fe deficiency reaches its greatest prevalence in populations subsisting on cereal- and legume-based diets. However, in a balanced diet containing animal protein a high intake of legumes is not considered a risk in terms of mineral supply. Furthermore, once phytate, and in certain legumes polyphenols, is degraded, legumes would become good sources of Fe and Zn as the content of these minerals is high.

Measurements of ultrasonic backscattered spectral centroid shift from spine in vivo: methodology and preliminary results.

PubMed

Garra, Brian S; Locher, Melanie; Felker, Steven; Wear, Keith A

2009-01-01

Ultrasonic backscatter measurements from vertebral bodies (L3 and L4) in nine women were performed using a clinical ultrasonic imaging system. Measurements were made through the abdomen. The location of a vertebra was identified from the bright specular reflection from the vertebral anterior surface. Backscattered signals were gated to isolate signal emanating from the cancellous interiors of vertebrae. The spectral centroid shift of the backscattered signal, which has previously been shown to correlate highly with bone mineral density (BMD) in human calcaneus in vitro, was measured. BMD was also measured in the nine subjects' vertebrae using a clinical bone densitometer. The correlation coefficient between centroid shift and BMD was r = -0.61. The slope of the linear fit was -160 kHz / (g/cm(2)). The negative slope was expected because the attenuation coefficient (and therefore magnitude of the centroid downshift) is known from previous studies to increase with BMD. The centroid shift may be a useful parameter for characterizing bone in vivo.

Transverse vibration technique to identify deteriorated wood floor systems

Treesearch

R.J. Ross; X. Wang; M.O. Hunt; L.A. Soltis

2002-01-01

The Forest Products Laboratory, USDA Forest Service, has been developing nondestructive evaluation (NDE) techniques to identify degradation of wood in structures and the performance characteristics that remain in the structure. This work has focused on using dynamic testing techniques, particularly stress wave and ultrasonic transmission NDE techniques for both...

Degradation of thiamethoxam by the synergetic effect between anodic oxidation and Fenton reactions.

PubMed

Meijide, J; Gómez, J; Pazos, M; Sanromán, M A

2016-12-05

In this work, a comparative study using anodic oxidation, Fenton and electro-Fenton treatments was performed in order to determine the synergic effect for the removal of thiamethoxan. The results determined that electro-Fenton process showed high efficiency in comparison with Fenton or anodic oxidation. After that, this hybrid process was optimized and the influence of iron catalyst concentration and applied current intensity on the degradation and mineralization were evaluated. Degradation profiles were monitored by high performance liquid chromatography (HPLC) being satisfactorily described by pseudo-first order kinetic model. At the optimal experimental conditions (300mA and 0.2mM Fe(+2)), the complete degradation of thiamethoxam was achieved after 10min. On the other hand, mineralization of thiamethoxam was monitored by total organic carbon (TOC) decay reaching more than 92% of TOC removal after 8h. Furthermore, a plausible mineralization pathway for the thiamethoxam degradation was proposed based on the identification of by-products such as aromatic intermediates, carboxylic acids and inorganic ions released throughout electro-Fenton process. Copyright © 2016 Elsevier B.V. All rights reserved.

Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems.

PubMed

Sharma, Mangalampalli V Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

2008-12-30

The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO2, H-MOR support and different wt% of TiO2 over the support on the photocatalytic degradation and influence of parameters such as TiO2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15wt% TiO2/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and approximately 80% mineralization occurred in 5h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS).

Removal of dicyclohexyl acetic acid from aqueous solution using ultrasound, ozone and their combination.

PubMed

Kumar, Pardeep; Headley, John; Peru, Kerry; Bailey, Jon; Dalai, Ajay

2014-01-01

Naphthenic acids are a complex mixture of organic components, some of which include saturated alkyl-substituted cycloaliphatic carboxylic acids and acyclic aliphatic acids. They are naturally found in hydrocarbon deposits like oil sand, petroleum, bitumen and crude oil. In this study, the oxidation of a relatively high molecular weight naphthenic acid (Dicyclohexyl acetic acid) was investigated using ozonation, ultrasonication and hydrogen peroxide alone and their combinations. Effects on oxidation of dicyclohexyl acetic acid (DAA) were measured for different concentrations of ozone ranging between 0.7 to 3.3 mg L(-1) and pH in the range 6 to 10. Ultrasonication and hydrogen peroxide alone were not effective to oxidize dicyclohexyl acetic acid, but combining ultrasonication with H2O2 had a significant effect on oxidation of dicyclohexyl acetic acid with maximum removal reaching to 84 ± 2.2% with 81 ± 2.1% reduction in chemical oxygen demand (COD). Synergistic effects were observed for combining ultrasonication with ozonation and resulted in 100% DAA removal with 98 ± 0.8% reduction in COD within 15 min at 3.3 mg L(-1) ozone concentration and 130 Watts ultrasonication power. The reaction conditions obtained for the maximum oxidation of DAA and COD removal were used for the degradation of naphthenic acids mixture extracted from oil sands process water (OSPW). The percentage oxidation of NAs mixture extracted from OSPW was 89.3 ± 1.1% in ozonation and combined ozonation and ultrasonication, but COD removal observed was 65 ± 1.2% and 78 ± 1.4% for ozonation and combined ozonation and ultrasonication treatments, respectively.

Lindane degradation by Candida VITJzN04, a newly isolated yeast strain from contaminated soil: kinetic study, enzyme analysis and biodegradation pathway.

PubMed

Salam, Jaseetha Abdul; Das, Nilanjana

2014-04-01

A new yeast strain was isolated from sugarcane cultivation field which was able to utilize lindane as sole carbon source for growth in mineral medium. The yeast was identified and named as Candida sp. VITJzN04 based on a polyphasic approach using morphological, biochemical and 18S rDNA, D1/D2 and ITS sequence analysis. The isolated yeast strain efficiently degraded 600 mg L⁻¹ of lindane within 6 days in mineral medium under the optimal conditions (pH 7; temperature 30 °C and inoculum dosage 0.06 g L⁻¹) with the least half-life of 1.17 days and degradation constant of 0.588 per day. Lindane degradation was tested with various kinetic models and results revealed that the reaction could be described best by first-order and pseudo first-order models. In addition, involvement of the enzymes viz. dechlorinase, dehalogenase, dichlorohydroquinone reductive dechlorinase, lignin peroxidase and manganese peroxidase was noted during lindane degradation. Addition of H2O2 in the mineral medium showed 32 % enhancement of lindane degradation within 3 days. Based on the metabolites identified by GC-MS and FTIR analysis, sequential process of lindane degradation by Candida VITJzN04 was proposed. To the best of our knowledge, this is the first report of isolation and characterization of lindane-degrading Candida sp. and elucidation of enzyme systems during the degradation process.

UV irradiation of biomarkers adsorbed on minerals under Martian-like conditions: Hints for life detection on Mars

NASA Astrophysics Data System (ADS)

Fornaro, Teresa; Boosman, Arjen; Brucato, John R.; ten Kate, Inge Loes; Siljeström, Sandra; Poggiali, Giovanni; Steele, Andrew; Hazen, Robert M.

2018-10-01

Laboratory simulations of Martian conditions are essential to develop quantitative models for the survival of organic biomarkers for future Mars exploration missions. In this work, we report the results of ultraviolet (UV) irradiation processing of biomarkers adsorbed on minerals under Martian-like conditions. Specifically, we prepared Mars soil analogues by doping forsterite, lizardite, antigorite, labradorite, natrolite, apatite and hematite minerals with organic compounds considered as potential biomarkers of extant terrestrial life such as the nucleotides adenosine monophosphate (AMP) and uridine monophosphate (UMP). We characterized such Mars soil analogues by means of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Confocal Raman Imaging Spectroscopy (CRIS), in order to get insights into the specific molecule-mineral interactions and explore the capabilities of different techniques to reveal diagnostic features of these biomarkers. Then, we performed irradiation experiments in the mid-UV spectral region under simulated Martian conditions and under terrestrial ambient conditions for comparison, monitoring the degradation process through DRIFTS. We observed that degradation under Martian-like conditions occurs much slower than in terrestrial ambient conditions. The minerals labradorite and natrolite mainly promote photodegradation of nucleotides, hematite and forsterite exhibit an intermediate degrading effect, while apatite, lizardite and antigorite do not show any significant catalytic effect on the degradation of the target organic species.

Isolation and characterization of an isoproturon mineralizing Sphingomonas sp. strain SH from a French agricultural soil.

PubMed

Hussain, Sabir; Devers-Lamrani, Marion; El Azhari, Najoi; Martin-Laurent, Fabrice

2011-06-01

The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an agricultural soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp. JEM-14, AB219361) and was designated Sphingomonas sp. strain SH. From this strain, a partial sequence of a 1,2-dioxygenase (catA) gene coding for an enzyme degrading catechol putatively formed during IPU mineralization was amplified. Phylogenetic analysis revealed that the catA sequence was related to Sphingomonas spp. and showed a lack of congruence between the catA and 16S rRNA based phylogenies, implying horizontal gene transfer of the catA gene cluster between soil microbiota. The IPU degrading ability of strain SH was strongly influenced by pH with maximum degradation taking place at pH 7.5. SH was only able to mineralize IPU and its known metabolites including 4-isopropylaniline and it could not degrade other structurally related phenylurea herbicides such as diuron, linuron, monolinuron and chlorotoluron or their aniline derivatives. These observations suggest that the catabolic abilities of the strain SH are highly specific to the metabolism of IPU.

Effects of sonochemical parameters and inorganic ions during the sonochemical degradation of crystal violet in water.

PubMed

Guzman-Duque, Fernando; Pétrier, Christian; Pulgarin, Cesar; Peñuela, Gustavo; Torres-Palma, Ricardo A

2011-01-01

This work deals with the ultrasonic degradation (800 kHz) of crystal violet (CV) under different experimental conditions. The effects of saturating gas (argon, carbon dioxide and air), CV concentration (2.45-1225 μmol L(-1)), pH (3-9) and power (20-80 W) were evaluated. The best performances were obtained at 80 W with argon as a saturating gas. The pH had no significant effect. The influence of several water matrices containing anions (chloride, sulphate and bicarbonate) and cations (Fe(2+)) on the sonolytic degradation of CV was also investigated. Significant differences were not observed with the presence of chloride and sulphate. However, at relatively low pollutant concentration (2.45 μmol L(-1)) bicarbonate showed a particular effect: a high bicarbonate concentration (350 mmol L(-1)) produced a detrimental effect, while a low bicarbonate concentration (3 mmol L(-1)) increased the efficiency of the process. The presence of Fe(2+) (1 mmol L(-1)) also increased the CV (49 μmol L(-1)) degradation by 32% after 180 min. Analyses of intermediates by GC-MS led to the identification of several sonochemical by-products: N,N-dimethylaminobenzene, 4-(N,N-dimethylamino)-4'-(N',N'-dimethylamino)benzophenone, and N,N,N',N'-tetramethyl-4,4'-diaminodiphenylmethane. The presence of these aromatic structures showed that the main ultrasonic CV degradation pathway is linked to the reaction with *OH radicals. At the end of the treatment, these early products were converted into biodegradable organic by-products which could be easily treated in a subsequent biological treatment. Copyright © 2010 Elsevier B.V. All rights reserved.

A simple method to determine mineralization of (14) C-labeled compounds in soil.

PubMed

Myung, Kyung; Madary, Michael W; Satchivi, Norbert M

2014-06-01

Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (14) C-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (14) C-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (14) C-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(14) C]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (14) C-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (14) C-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices. © 2014 SETAC.

Damage Characterization and Real-Time Health Monitoring of Aerospace Materials Using Innovative NDE Tools

NASA Astrophysics Data System (ADS)

Matikas, Theodore E.

2010-07-01

The objective of this work is to characterize the damage and monitor in real-time aging structural components used in aerospace applications by means of advanced nondestructive evaluation techniques. Two novel experimental methodologies are used in this study, based on ultrasonic microscopy and nonlinear acoustics. It is demonstrated in this work that ultrasonic microscopy can be successfully utilized for local elastic property measurement, crack-size determination as well as for interfacial damage evaluation in high-temperature materials, such as metal matrix composites. Nonlinear acoustics enables real-time monitoring of material degradation in aerospace structures. When a sinusoidal ultrasonic wave of a given frequency and of sufficient amplitude is introduced into a nonharmonic solid, the fundamental wave distorts as it propagates, and therefore the second and higher harmonics of the fundamental frequency are generated. Measurements of the amplitude of these harmonics provide information on the coefficient of second- and higher-order terms of the stress-strain relation for a nonlinear solid. It is shown in this article that the material bulk nonlinear parameter for metallic alloy samples at different fatigue levels exhibits large changes compared to linear ultrasonic parameters, such as velocity and attenuation.

Anaerobic digestion of ultrasonicated sludge at different solids concentrations - Computation of mass-energy balance and greenhouse gas emissions.

PubMed

Pilli, Sridhar; Yan, S; Tyagi, R D; Surampalli, R Y

2016-01-15

Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10(6) g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output - energy input) of total dry solids (TDS) was 7.89 × 10(-6) kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bioavailable Carbon and the Relative Degradation State of Organic Matter in Active Layer and Permafrost Soils

NASA Astrophysics Data System (ADS)

Jastrow, J. D.; Burke, V. J.; Vugteveen, T. W.; Fan, Z.; Hofmann, S. M.; Lederhouse, J. S.; Matamala, R.; Michaelson, G. J.; Mishra, U.; Ping, C. L.

2015-12-01

The decomposability of soil organic carbon (SOC) in permafrost regions is a key uncertainty in efforts to predict carbon release from thawing permafrost and its impacts. The cold and often wet environment is the dominant factor limiting decomposer activity, and soil organic matter is often preserved in a relatively undecomposed and uncomplexed state. Thus, the impacts of soil warming and permafrost thaw are likely to depend at least initially on the genesis and past history of organic matter degradation before its stabilization in permafrost. We compared the bioavailability and relative degradation state of SOC in active layer and permafrost soils from Arctic tundra in Alaska. To assess readily bioavailable SOC, we quantified salt (0.5 M K2SO4) extractable organic matter (SEOM), which correlates well with carbon mineralization rates in short-term soil incubations. To assess the relative degradation state of SOC, we used particle size fractionation to isolate fibric (coarse) from more degraded (fine) particulate organic matter (POM) and separated mineral-associated organic matter into silt- and clay-sized fractions. On average, bulk SOC concentrations in permafrost were lower than in comparable active layer horizons. Although SEOM represented a very small proportion of the bulk SOC, this proportion was greater in permafrost than in comparable active layer soils. A large proportion of bulk SOC was found in POM for all horizons. Even for mineral soils, about 40% of bulk SOC was in POM pools, indicating that organic matter in both active layer and permafrost mineral soils was relatively undecomposed compared to typical temperate soils. Not surprisingly, organic soils had a greater proportion of POM and mineral soils had greater silt- and clay-sized carbon pools, while cryoturbated soils were intermediate. For organic horizons, permafrost organic matter was generally more degraded than in comparable active layer horizons. However, in mineral and cryoturbated horizons, the presence of permafrost appeared to have little effect on SOC distribution among size fractions. Future studies will investigate the utility of using organic matter pools defined by SEOM and particle size to predict the bioavailable pools characterized through more time-consuming long-term incubation studies of permafrost region soils.

p-Aminophenol degradation by ozonation combined with sonolysis: operating conditions influence and mechanism.

PubMed

He, Zhiqiao; Song, Shuang; Ying, Haiping; Xu, Lejin; Chen, Jianmeng

2007-07-01

The degradation of p-aminophenol (PAP) in aqueous solution by sonolysis, by ozonation, and by a combination of both was investigated in laboratory-scale experiments. Operation parameters such as pH, temperature, ultrasonic energy density and ozone dose were optimized with regard to the efficiency of PAP removal. The concentration of PAP during the reaction was detected by high-pressure liquid chromatography. The concentrations of ammonium ions and nitrate ions were monitored during the degradation. Intermediate products such as 4-iminocyclohexa-2,5-dien-1-one, phenol, but-2-enedioic acid, and acetic acid were detected by gas chromatography coupled with mass spectrometry. The degradation rate of PAP was higher in the combined system than in the linear combination of separate experiments. The degradation efficiency was decreased rapidly when n-butanol was added to the combined reaction system, which showed that some radical reaction might proceed during the laboratory experiments.

Atrazine degradation by bioaugmented sediment from constructed wetlands.

PubMed

Runes, H B; Jenkins, J J; Bottomley, P J

2001-10-01

The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.

Understanding of Materials State and its Degradation using Non-Linear Ultrasound Approaches for Lamb Wave Propagation

DTIC Science & Technology

2015-05-31

Institution : Indian Institute of Technology Madras - Mailing Address : MDS 301, Department of Mechanical Engineering, IIT Campus, Chennia INDIA 600036...in ceramic composites using an ultrasonic guided wave scan system”, 30th Annual Rev. of Quan. NDE, 2003; NASA /TM-2003-212518. [15] J Y Kim, J Qu

ULTRASONICALLY INDUCED DEGRADATION OF MICROCYSTIN-LR AND -RR: IDENTIFICATION OF PRODUCTS, EFFECTS OF PH, FORMATION AND DESTRUCTION OF PEROXIDES

EPA Science Inventory

Microcystins (MCs) are a family of toxic peptides produced by a number of cyanobacteria commonly found in lakes, water reservoirs, and recreational facilities. The increased eutrophication of freshwater supplies has led to an increase in the incidence of cyanobacterial harmful al...

Effect of concentration gradients on biodegradation in bench-scale sand columns with HYDRUS modeling of hydrocarbon transport and degradation.

PubMed

Horel, Agota; Schiewer, Silke; Misra, Debasmita

2015-09-01

The present research investigated to what extent results obtained in small microcosm experiments can be extrapolated to larger settings with non-uniform concentrations. Microbial hydrocarbon degradation in sandy sediments was compared for column experiments versus homogenized microcosms with varying concentrations of diesel, Syntroleum, and fish biodiesel as contaminants. Syntroleum and fish biodiesel had higher degradation rates than diesel fuel. Microcosms showed significantly higher overall hydrocarbon mineralization percentages (p < 0.006) than columns. Oxygen levels and moisture content were likely not responsible for that difference, which could, however, be explained by a strong gradient of fuel and nutrient concentrations through the column. The mineralization percentage in the columns was similar to small-scale microcosms at high fuel concentrations. While absolute hydrocarbon degradation increased, mineralization percentages decreased with increasing fuel concentration which was corroborated by saturation kinetics; the absolute CO2 production reached a steady plateau value at high substrate concentrations. Numerical modeling using HYDRUS 2D/3D simulated the transport and degradation of the investigated fuels in vadose zone conditions similar to those in laboratory column experiments. The numerical model was used to evaluate the impact of different degradation rate constants from microcosm versus column experiments.

CTAB-assisted ultrasonic synthesis, characterization and photocatalytic properties of WO{sub 3}

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

Sánchez-Martínez, D., E-mail: dansanm@gmail.com; Gomez-Solis, C.; Torres-Martinez, Leticia M.

2015-01-15

Highlights: • WO{sub 3} 2D nanostructures were synthesized by ultrasound method assisted with CTAB. • WO{sub 3} morphology was mainly of rectangular nanoplates with a thickness of ∼50 nm. • The highest surface area value of WO{sub 3} was obtained to lowest concentration of CTAB. • WO{sub 3} activity was attributed to morphology, surface area and the addition of CTAB. • WO{sub 3} nanoplates were able to causing almost complete mineralization of rhB and IC. - Abstract: WO{sub 3} 2D nanostructures have been prepared by ultrasound synthesis method assisted with CTAB using different molar ratios. The formation of monoclinic crystalmore » structure of WO{sub 3} was confirmed by X-ray powder diffraction (XRD). The characterization of the WO{sub 3} samples was complemented by analysis of scanning electron microscopy (SEM), which revealed morphology mainly of rectangular nanoplates with a thickness of around 50 nm and length of 100–500 nm. Infrared spectroscopy (FT-IR) was used to confirm the elimination of the CTAB in the synthesized samples. The specific surface area was determinate by the BET method and by means of diffuse reflectance spectroscopy (DRS) it was determinate the band-gap energy (E{sub g}) of the WO{sub 3} samples. The photocatalytic activity of the WO{sub 3} oxide was evaluated in the degradation reactions of rhodamine B (rhB) and indigo carmine (IC) under Xenon lamp irradiation. The highest photocatalytic activity was observed in the samples containing low concentration of CTAB with morphology of rectangular nanoplates and with higher surface area value than commercial WO{sub 3}. Photodegradation of rhB and IC were followed by means of UV–vis absorption spectra. The mineralization degree of organic dyes by WO{sub 3} photocatalyst was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 92% for rhB and 50% for IC after 96 h of lamp irradiation.« less

Geometric Limitations Of Ultrasonic Measurements

NASA Astrophysics Data System (ADS)

von Nicolai, C.; Schilling, F.

2006-12-01

Laboratory experiments are a key for interpreting seismic field observations. Due to their potential in many experimental set-ups, the determination of elastic properties of minerals and rocks by ultrasonic measurements is common in Geosciences. The quality and thus use of ultrasonic data, however, strongly depends on the sample geometry and wavelength of the sound wave. Two factors, the diameter-to-wavelength- ratio and the diameter-to-length-ratio, are believed to be the essential parameters to affect ultrasonic signal quality. In this study, we determined under well defined conditions the restricting dimensional parameters to test the validity of published assumptions. By the use of commercial ultrasonic transducers a number of experiments were conducted on aluminium, alumina, and acrylic glass rods of varying diameter (30-10 mm) and constant length. At each diameter compressional wave travel times were measured by pulse- transmission method. From the observed travel times ultrasonic wave velocities were calculated. One additional experiment was performed with a series of square-shaped aluminium blocks in order to investigate the effect of the geometry of the samples cross-sectional area. The experimental results show that the simple diameter-to-wavelength ratios are not valid even under idealized experimental conditions and more complex relation has to be talen into account. As diameter decreases the P-waves direct phase is increasingly interfered and weakened by sidewall reflections. At very small diameters compressional waves are replaced by bar waves and P-wave signals become non resolvable. Considering the suppression of both effects, a critical D/ë-ratio was determined and compared to experimental set-ups from various publications. These tests indicate that some published and cited data derived from small diameter set-ups are out off the range of physical possibility.

Selecting the best AOP for isoxazolyl penicillins degradation as a function of water characteristics: Effects of pH, chemical nature of additives and pollutant concentration.

PubMed

Villegas-Guzman, Paola; Silva-Agredo, Javier; Florez, Oscar; Giraldo-Aguirre, Ana L; Pulgarin, Cesar; Torres-Palma, Ricardo A

2017-04-01

To provide new insights toward the selection of the most suitable AOP for isoxazolyl penicillins elimination, the degradation of dicloxacillin, a isoxazolyl penicillin model, was studied using different advanced oxidation processes (AOPs): ultrasound (US), photo-Fenton (UV/H 2 O 2 /Fe 2+ ) and TiO 2 photocatalysis (UV/TiO 2 ). Although all processes achieved total removal of the antibiotic and antimicrobial activity, and increased the biodegradability level of the solutions, significant differences concerning the mineralization extend, the pH of the solution, the pollutant concentration and the chemical nature of additives were found. UV/TiO 2 reached almost complete mineralization; while ∼10% mineralization was obtained for UV/H 2 O 2 /Fe 2+ and practically zero for US. Effect of initial pH, mineral natural water and the presence of organic (glucose, 2-propanol and oxalic acid) were then investigated. UV/H 2 O 2 /Fe 2+ and US processes were improved in acidic media, while natural pH favored UV/TiO 2 system. According to both the nature of the added organic compound and the process, inhibition, no effect or enhancement of the degradation rate was observed. The degradation in natural mineral water showed contrasting results according to the antibiotic concentration: US process was enhanced at low concentration of dicloxacillin followed by detrimental effects at high substrate concentrations. A contrary effect was observed during photo-Fenton, while UV/TiO 2 was inhibited in all of cases. Finally, a schema illustrating the enhancement or inhibiting effects of water matrix is proposed as a tool for selecting the best process for isoxazolyl penicillins degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Effect of Different Mixing Methods on Working Time, Setting Time, Dimensional Changes and Film Thickness of Mineral Trioxide Aggregate and Calcium-Enriched Mixture.

PubMed

Shahi, Shahriar; Ghasemi, Negin; Rahimi, Saeed; Yavari, Hamidreza; Janani, Maryam; Mokhtari, Hadi; Bahari, Mahmood; Rabbani, Parastu

2015-01-01

The aim of the present study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic mixing) on the physical properties the working time (WT), setting time (ST), dimensional changes (DC) and film thickness (FT)] of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA). The mentioned physical properties were determined using the ISO 6786:2001 specification. Six samples of each material were prepared for three mixing techniques (totally 36 samples). Data were analyzed using descriptive statistics, two-way ANOVA and Post Hoc Tukey's tests. The level of significance was defined at 0.05. Irrespective of mixing technique, there was no significant difference between the WT and FT of the tested materials. Except for the DC of MTA and the FT of the all materials, other properties were significantly affected with mixing techniques (P<0.05). The ultrasonic technique decreased the ST of MTA and CEM cement and increased the WT of CEM cement (P<0.05). The mixing technique of the materials had no significant effect on the dimensional changes of MTA and the film thickness of both materials.

Vertical small scale variations of sorption and mineralization of three herbicides in subsurface limestone and sandy aquifer

NASA Astrophysics Data System (ADS)

Janniche, G. S.; Mouvet, C.; Albrechtsen, H.-J.

2011-04-01

Vertical variation in sorption and mineralization potential of mecoprop (MCPP), isoproturon and acetochlor were investigated at low concentrations (μg-range) at the cm-scale in unsaturated sub-surface limestone samples and saturated sandy aquifer samples from an agricultural catchment in Brévilles, France. From two intact core drills, four heterogenic limestone sections were collected from 4.50 to 26.40 m below surface (mbs) and divided into 12 sub-samples of 8-25 cm length, and one sandy aquifer section from 19.20 to 19.53 m depth divided into 7 sub-samples of 4-5 cm length. In the sandy aquifer section acetochlor and isoproturon sorption increased substantially with depth; in average 78% (acetochlor) and 61% (isoproturon) per 5 cm. Also the number of acetochlor and isoproturon degraders (most-probable-number) was higher in the bottom half of the aquifer section (93-> 16 000/g) than in the upper half (4-71/g). One 50 cm long limestone section with a distinct shift in color showed a clear shift in mineralization, number of degraders and sorption: In the two brown, uppermost samples, up to 31% mecoprop and up to 9% isoproturon was mineralized during 231 days, the numbers of mecoprop and isoproturon degraders were 1300 to > 16 000/g, and the sorption of both isoproturon and acetochlor was more than three times higher, compared to the two deeper, grayish samples just below where mineralization (≤ 4%) and numbers of degraders (1-520/g) were low for all three herbicides. In both unsaturated limestone and sandy aquifer, variations and even distinct shifts in both mineralization, number of specific degraders and sorption were seen within just 4-15 cm of vertical distance. A simple conceptual model of herbicides leaching to groundwater through a 10 m unsaturated limestone was established, and calculations showed that a 30 cm active layer with the measured sorption and mineralization values hardly impacted the fate of the investigated herbicides, whereas a total thickness of layers of 1 m would substantially increase natural attenuation.

Hermetic edge sealing of photovoltaic modules

NASA Astrophysics Data System (ADS)

Nowlan, M. J.

1983-07-01

The feasibility of using an electrostatic bonding (ESB) and ultrasonic welding process to produce hermetic edge seals on terrestrial solar cell modules was investigated. The fabrication sequence is to attach an aluminum foil "gasket' to the perimeter of a glass sheet. A cell circuit is next encapsulated inside the gasket, and its aluminum foil back cover is seam welded ultrasonically to the gasket. An ESB process for sealing aluminum to glass was developed in an ambient air atmosphere, which eliminates the requirement for a vacuum or pressure vessel. An ultrasonic seam welding process was also developed which did not degrade the quality of the ESB seal. Good quality welds with minimal deformation were produced. The effectiveness of the above described sealing techniques was tested by constructing 400 sq cm (8 x 8 s64 sq in) sample modules, and then subjecting them to nondestructive fine and gross leak tests. The gross leak tests identified several different causes of leaks which were then eliminated by modifying the assembly process.

Hermetic edge sealing of photovoltaic modules

NASA Technical Reports Server (NTRS)

Nowlan, M. J.

1983-01-01

The feasibility of using an electrostatic bonding (ESB) and ultrasonic welding process to produce hermetic edge seals on terrestrial solar cell modules was investigated. The fabrication sequence is to attach an aluminum foil "gasket' to the perimeter of a glass sheet. A cell circuit is next encapsulated inside the gasket, and its aluminum foil back cover is seam welded ultrasonically to the gasket. An ESB process for sealing aluminum to glass was developed in an ambient air atmosphere, which eliminates the requirement for a vacuum or pressure vessel. An ultrasonic seam welding process was also developed which did not degrade the quality of the ESB seal. Good quality welds with minimal deformation were produced. The effectiveness of the above described sealing techniques was tested by constructing 400 sq cm (8 x 8 s64 sq in) sample modules, and then subjecting them to nondestructive fine and gross leak tests. The gross leak tests identified several different causes of leaks which were then eliminated by modifying the assembly process.

Ultraviolet/ultrasound-activated persulfate for degradation of drug by zinc selenide quantum dots: Catalysis and microbiology study.

PubMed

Fakhri, Ali; Naji, Mahsa; Tahami, Shiva

2017-05-01

In this study, wet chemical method used for ZnSe quantum dots (QDs) and characterized by, UV-vis, photoluminescence spectroscopy, X-ray diffraction and transmission electron microscopy. The crystallites size of ZnSe QDs was 4.0nm. The average diameters of ZnSe QDs were 3.0-5.3nm. Ritalin was degraded using the UV/ZnSe QDs/persulfate process. The several parameters investigated for the influence of Rtialin degradation were the temperature, the persulfate concentration, and the initial Ritalin concentration. The values of optimum parameters ware room temperature, concentration persulfate 5mmol/L and initial Ritalin concentration 0.09mmol/L. Comparative analyses showed the maximum degradation of Ritalin was found for ZnSe/persulfate under ultra-visible and ultra-sonic irradiation process. Comparative analysis showed the maximum degradation of Ritalin was found for ZnSe/persulfate under ultra-visible and ultra-sonic irradiation process. The values of first-order rate constants from degradation of Ritalin at 25°C were 0.96×10 -2 , 1.09×10 -2 , 1.59×10 -2 and 2.19×10 -2 for US/PS, UV/PS, ZnSe/US/PS and ZnSe/UV/PS system, respectively. The antibacterial activity evaluation against two bacterials, including Gram-positive bacteria Staphylococcus aureus (ATCC 43300), Bacillus megaterium (ATCC 14581) and Gram-negative bacteria Pseudomonas aeruginosa (ATCC 27853), Micrococcus luteus (ATCC 4698) was considered. It was found that the MIC values for the antibacterial assay in the presence of ZnSe QDs were around 0.30mM with 64.0, 66.0, 79.2, and 83.5% inhibition for the S. aureus, B. megaterium, P. aeruginosa and M. luteus bacterial strains, respectively. Then, results show that the ZnSe QDs have antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-01-01

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

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

PubMed

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

2014-11-01

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

Destruction of amphetamine in aqueous solution using gamma irradiation

NASA Astrophysics Data System (ADS)

Alkhuraiji, Turki S.; Ajlouni, Abdul-Wali

2017-10-01

Amphetamine-type stimulants are among the most prevalent and widespread commonly abused drugs. Amphetamine and its derivatives were detected in aquatic environment. This study aimed to demonstrate experimentally the ability of γ-irradiation combined with persulfate anions (S2O82-) to degrade and mineralize the amphetamine in aqueous solution. An initial amphetamine concentration of 125 μM in distilled water was completely degraded by a γ-ray dose of 2.8 kGy. Generation of the sulfate radical (SO4•-) from the fast reaction of added S2O82- with hydrated electrons (eaq-; keaq-/S2O82- = 1.1×1010 M-1 s-1) improved the efficiency of amphetamine degradation and mineralization. A γ-ray dose of 0.667 and 0.350 kGy in the absence and presence of S2O82- anions degraded 90% of the amphetamine, respectively. For γ-ray/free O2 and γ-ray/S2O82- systems, 11.5 and 7 kGy was required for 50% amphetamine mineralization, respectively. Addition of HCO3- anions lowered the amphetamine degradation yield, whereas N2 gas, SO42-, and Cl- anions had a negligible effect.

Ultrasonic Studies of Composites Undergoing Thermal and Fatigue Loading

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Winfree, William P.; Johnston, Patrick H.

1997-01-01

New composite materials possess attractive properties for use in advanced aircraft. A necessary requirement for their introduction into aeronautic use is an accurate understanding of their long term aging processes so that proper design criteria can be established. In order to understand those properties, these composites must be exposed to thermal and load cycles that are characteristic of flight conditions. Additionally, airline companies will require nondestructive evaluation (NDE) methods that can be used in the field to assess the condition of these new materials as they age. As part of an effort to obtain the required information about new composites for aviation use, we are performing ultrasonic measurements both in the NDE laboratory and in the materials testing laboratory at NASA. The materials testing laboratory is equipped with environmental chambers mounted on load frames so that composite samples can be exposed to thermal and loading cycles representative of flight protocols. Applying both temperature and load simultaneously will help to highlight temperature and load interactions during the aging of these composite materials. This study reports on our initial ultrasonic attenuation results from thermoset and thermoplastic composite samples. Ultrasonic attenuation measurements have been used reliably to assess the effects of material degradation. For example, recently, researchers have shown that by using frequencies of ultrasound on the order of 24 MHz, they could obtain adequate contrast in the evaluation of thermal degradation in these composites. This paper will present data that shows results at a lower frequency range. In addition, we report results on the frequency dependence of attenuation as the slope of attenuation with respect to frequency, beta = delta alpha (f) / delta f. The slope of attenuation is an attractive parameter since it is quantitative, yet does not require interface corrections like conventional quantitative attenuation measurements. This is a consequence of the assumption that interface correction terms are frequently independent. Uncertainty in those corrections terms compromises the value of conventional quantitative attenuation data.

Integrated ultrasonic and petrographical characterization of carbonate building materials

NASA Astrophysics Data System (ADS)

Ligas, Paola; Fais, Silvana; Cuccuru, Francesco

2014-05-01

This paper presents the application of non-destructive ultrasonic techniques in evaluating the conservation state and quality of monumental carbonate building materials. Ultrasonic methods are very effective in detecting the elastic characteristics of the materials and thus their mechanical behaviour. They are non-destructive and effective both for site and laboratory tests, though it should be pointed out that ultrasonic data interpretation is extremely complex, since elastic wave velocity heavily depends on moisture, heterogeneity, porosity and other physical properties of the materials. In our study, considering both the nature of the building materials and the constructive types of the investigated monuments, the ultrasonic investigation was carried out in low frequency ultrasonic range (24 kHz - 54 kHz) with the aim of detecting damages and degradation zones and assessing the alterability of the investigated stones by studying the propagation of the longitudinal ultrasonic pulses. In fact alterations in the materials generally cause a decrease in longitudinal pulse velocity values. Therefore starting from longitudinal velocity values the elasto-mechanical behaviour of the stone materials can be deduced. To this aim empirical and effective relations between longitudinal velocity and mechanical properties of the rocks can be used, by transferring the fundamental concepts of the studies of reservoir rocks in the framework of hydrocarbon research to the diagnostic process on stone materials. The ultrasonic measurements were performed both in laboratory and in situ using the Portable Ultrasonic Non-Destructive Digital Indicating Tester (PUNDIT) by C.N.S. Electronics LTD. A number of experimental sessions were carried out choosing different modalities of data acquisition. On the basis of the results of the laboratory measurements, an in situ ultrasonic survey on significant monuments, have been carried out. The ultrasonic measurements were integrated by a petrographical and petrophysical study of the investigated stone materials to correlate their petrographical-petrophysical features with the elastic ones. From this integrated study results that the modifications in the elasto-mechanical and petrographical-petrophysical features of the investigated carbonate materials are the main causes which reduce their quality as building materials. The use of the ultrasonic method integrated with information on petrography and petrophysics of the rocks has been successful to assess the rock quality and better understanding their alteration process. Acknowledgments: This work was financially supported by Sardinian Local Administration (RAS - LR 7 August 2007, n.7, Promotion of Scientific Research and Innovation in Sardinia - Italy, Responsible Scientist: S. Fais).

Single, simultaneous and sequential applications of ultrasonic frequencies for the elimination of ibuprofen in water.

PubMed

Ziylan-Yavas, Asu; Ince, Nilsun H

2018-01-01

The study is about the assessment of single and multi-frequency operations for the overall degradation of a widely consumed analgesic pharmaceutical-ibuprofen (IBP). The selected frequencies were in the range of 20-1130kHz emissions coming from probes, baths and piezo-electric transducers attached to plate-type devices. Multi-frequency operations were applied either simultaneously as "duals", or sequentially at fixed time intervals; and the total reaction time in all operations was 30-min. The work also covers evaluation of the effect of zero-valent iron (ZVI) on the efficiency of the degradation process and the performance of the reaction systems. It was found that low-frequency probe type devices especially at 20kHz were ineffective when applied singly and without ZVI, and relatively more effective in combined-frequency operations in the presence of ZVI. The power efficiencies of the reactors and/or reaction systems showed that 20-kHz probe was considerably more energy intensive than all others, and was therefore not used in multi-frequency operations. The most efficient reactor in terms of power consumption was the bath (200kHz), which however provided insufficient mineralization of the test chemical. The highest percentage of TOC decay (37%) was obtained in a dual-frequency operation (40/572kHz) with ZVI, in which the energy consumption was neither low nor exceptionally too high. A sequential operation (40+200kHz) in that respect was more efficient, because it required much less energy for a similar TOC decay performance (30%). In general, the degradation of IBP increased with increased power consumption, which in turn reduced the sonochemical yield. The study also showed that advanced Fenton reactions with ZVI were faster in the presence of ultrasound, and the metal was very effective in improving the performance of low-frequency operations. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrasonic effects on titanium tanning of leather.

PubMed

Peng, Biyu; Shi, Bi; Sun, Danhong; Chen, Yaowen; Shelly, Dennis C

2007-03-01

The effects of ultrasound on titanium tanning of leather were investigated. Either 20 or 40 kHz ultrasound was applied to the titanium tanning of pigskins. Five different treatment conditions were carried out and the effects were examined, such as leather shrinkage temperature (T(s)), titanium content and titanium distribution in the leather. Overall heat loading was carefully controlled. Results showed that 20 kHz ultrasound effectively improves titanium agent penetration into the hide and increases the leather's shrinkage temperature. Doubling the frequency to 40 kHz produced negligible enhancements. An impressive 105.6 degrees C T(s) was achieved using 20 kHz ultrasound pretreatment of the tanning liquor followed by 20 kHz ultrasound in the tanning mixture (liquor plus pigskins) in a special salt-free medium. Finally, using a unique ultrasonic tanning drum with 26.5 kHz ultrasound, the T(s) reached a record level of 106.5 degrees C, a value not achieved in conventional (no ultrasound) titanium tanning. The ultrasonic effects on titanium tanning of leather are judged to make a superior mineral tanned leather.

Mineral induced mechanochemical degradation: the imazaquin case.

PubMed

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

2009-03-01

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

Degradation and mineralization of 2,4,6-trinitroresorcine in various photochemical systems.

PubMed

Khue, Do Ngoc; Chat, Nguyen Van; Minh, Do Binh; Lam, Tran Dai; Lan, Pham Hong; Loi, Vu Duc

2013-05-01

Comparison was observed for degradation and mineralization of the explosive 2,4,6-trinitroresorcine (TNR) in different photochemical systems TNR/UV, TNR/UV/TiO2, TNR/UV/H2O2, TNR/UV/O3, TNR/UV/TiO2/H2O2 and TNR/UV/TiO2/O3 using High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC/MS) and Total Organic Carbon (TOC) analysis. Addition of oxidizing agents such as H2O2 or O3 accelerated the rate of TNR conversion and mineralization. Highest reaction rate was obtained in TNR/UV/TiO2/H2O2 system. The intermediate products were characterized and identified by LS-MS technique. The similarity in intermediate products of TNR suggested the analogous reaction pathways of the TNR degradation by these different systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Anaerobic biodegradation of phenolic compounds in digested sludge.

PubMed Central

Boyd, S A; Shelton, D R; Berry, D; Tiedje, J M

1983-01-01

We examined the anaerobic degradation of phenol and the ortho, meta, and para isomers of chlorophenol, methoxyphenol, methylphenol (cresol), and nitrophenol in anaerobic sewage sludge diluted to 10% in a mineral salts medium. Of the 12 monosubstituted phenols studied, only p-chlorophenol and o-cresol were not significantly degraded during an 8-week incubation period. The phenol compounds degraded and the time required for complete substrate disappearance (in weeks) were: phenol (2), o-chlorophenol (3), m-chlorophenol (7), o-methoxyphenol (2), m- and p-methoxyphenol (1), m-cresol (7), p-cresol (3), and o-, m-, and p-nitrophenol (1). Complete mineralization of phenol, o-chlorophenol, m-cresol, p-cresol, o-nitrophenol, p-nitrophenol, and o-, m-, and p-methoxyphenol was observed. In general, the presence of Cl and NO2 groups on phenols inhibited methane production. Elimination or transformation of these substituents was accompanied by increased methane production, o-Chlorophenol was metabolized to phenol, which indicated that dechlorination was the initial degradation step. The methoxyphenols were transformed to the corresponding dihydroxybenzene compounds, which were subsequently mineralized. PMID:6614908

Electrochemical degradation and mineralization of glyphosate herbicide.

PubMed

Tran, Nam; Drogui, Patrick; Doan, Tuan Linh; Le, Thanh Son; Nguyen, Hoai Chau

2017-12-01

The presence of herbicide is a concern for both human and ecological health. Glyphosate is occasionally detected as water contaminants in agriculture areas where the herbicide is used extensively. The removal of glyphosate in synthetic solution using advanced oxidation process is a possible approach for remediation of contaminated waters. The ability of electrochemical oxidation for the degradation and mineralization of glyphosate herbicide was investigated using Ti/PbO 2 anode. The current intensity, treatment time, initial concentration and pH of solution are the influent parameters on the degradation efficiency. An experimental design methodology was applied to determine the optimal condition (in terms of cost/effectiveness) based on response surface methodology. Glyphosate concentration (C 0  = 16.9 mg L -1 ) decreased up to 0.6 mg L -1 when the optimal conditions were imposed (current intensity of 4.77 A and treatment time of 173 min). The removal efficiencies of glyphosate and total organic carbon were 95 ± 16% and 90.31%, respectively. This work demonstrates that electrochemical oxidation is a promising process for degradation and mineralization of glyphosate.

Nondestructive evaluation tools and experimental studies for monitoring the health of space propulsion systems

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1991-01-01

An overview is given of background and information on space propulsion systems on both the programmatic and technical levels. Feasibility experimental studies indicate that nondestructive evaluation tools such as ultrasonic, eddy current and x-ray may be successfully used to monitor the life limiting failure mechanisms of space propulsion systems. Encouraging results were obtained for monitoring the life limiting failure mechanisms for three space propulsion systems; the degradation of tungsten arcjet and magnetoplasmadynamic electrodes; presence and thickness of spallable electrically conducting molybdenum films in ion thrusters; and the degradation of the catalyst in hydrazine thrusters.

30 CFR 875.15 - Reclamation priorities for noncoal program.

Code of Federal Regulations, 2011 CFR

2011-07-01

... from the extreme danger of adverse effects of mineral mining and processing practices; (2) The protection of public health, safety, and general welfare from the adverse effects of mineral mining and... degraded by the adverse effects of mineral mining and processing practices. (c) Enhancement of facilities...

30 CFR 875.15 - Reclamation priorities for noncoal program.

Code of Federal Regulations, 2010 CFR

2010-07-01

... from the extreme danger of adverse effects of mineral mining and processing practices; (2) The protection of public health, safety, and general welfare from the adverse effects of mineral mining and... degraded by the adverse effects of mineral mining and processing practices. (c) Enhancement of facilities...

30 CFR 875.15 - Reclamation priorities for noncoal program.

Code of Federal Regulations, 2012 CFR

2012-07-01

... from the extreme danger of adverse effects of mineral mining and processing practices; (2) The protection of public health, safety, and general welfare from the adverse effects of mineral mining and... degraded by the adverse effects of mineral mining and processing practices. (c) Enhancement of facilities...

30 CFR 875.15 - Reclamation priorities for noncoal program.

Code of Federal Regulations, 2014 CFR

2014-07-01

... from the extreme danger of adverse effects of mineral mining and processing practices; (2) The protection of public health, safety, and general welfare from the adverse effects of mineral mining and... degraded by the adverse effects of mineral mining and processing practices. (c) Enhancement of facilities...

Stress wave attenuation in thin structures by ultrasonic through-transmission

NASA Technical Reports Server (NTRS)

Lee, S. S.; Williams, J. H., Jr.

1980-01-01

The steady state amplitude of the output of an ultrasonic through transmission measurement is analyzed and the result is given in closed form. Provided that the product of the input and output transduction ratios; the specimen-transducer reflection coefficient; the specimen-transducer phase shift parameter; and the material phase velocity are known, this analysis gives a means for determining the through-thickness attenuation of an individual thin sample. Multiple stress wave reflections are taken into account and so signal echoes do not represent a difficulty. An example is presented for a graphite fiber epoxy composite (Hercules AS/3501-6). A direct method for continuous or intermittent monitoring of through thickness attenuation of plate structures which may be subject to service structural degradation is provided.

Enhanced degradation performances of plate-like micro/nanostructured zero valent iron to DDT.

PubMed

Kang, Shenghong; Liu, Shengwen; Wang, Huimin; Cai, Weiping

2016-04-15

Micro/nanostructured zero valent iron (MNZVI) is successfully mass-synthesized by ball-milling the industrially-reduced iron powders. The as-prepared MNZVI is plate-like in morphology with about 2-5μm in planar size and 35-55nm in thickness, and ∼16m(2)/g in specific surface area. Such plate-like MNZVI has demonstrated much higher degradation performances to DDT [or 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane] in the aqueous solution than the commercial ZVI powders under acidic conditions. The MNZVI-induced DDT degradation is also much faster than the previously reported results. The time-dependent DDT removal amount can be described by the pseudo first-order kinetic model. Further experiments have shown that more than 50% of DDT can be mineralized in 20min and the rest is dechlorinated to DDX (the products with less chlorine). It has been revealed that the DDT degradation could be attributed to the acid assisted ZVI-induced mineralization and dechlorination. The mineralization process is dominant during the initial stage within 20min, and the dechlorination is the main reaction in the anaphase of the degradation. This work not only deepens understanding of DDT degradation but also could provide a highly efficient material for the practical treatment of the DDT in a real environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultrasonic extraction of arsenic and selenium from rocks associated with mountaintop removal/valley fills coal mining: Estimation of bioaccessible concentrations.

PubMed

Pumure, I; Renton, J J; Smart, R B

2010-03-01

Ultrasonic extraction (UE) was used to estimate the total bioaccessible fractions of arsenic and selenium released from rocks associated with mountaintop removal/valley fill coal mining. The combined readily bioaccessible amounts of arsenic and selenium in water soluble, exchangeable and NaOH fractions can be extracted from the solid phase within a 20 or 25 min application of 200 W cm(-2) ultrasound energy in nanopure water for selenium and arsenic, respectively. Application of a two-way ANOVA predicted that there are no significant differences (p0.001, n=12) in the extracted arsenic and selenium concentrations between the combined bioaccessible and ultrasonic extracts. The mechanisms for the UE of arsenic and selenium are thought to involve the formation of secondary minerals on the particle surfaces which eventually dissolve with continued sonication. This is supported by the presence of transient Si-O stretching and OH absorption and bending ATR-FTIR peaks at 795.33 cm(-1), 696.61 cm(-1) and 910.81 cm(-1). The subsequent dissolution of secondary minerals is followed by the release of chemical species that include selenium and arsenic. Release rates decrease after the ultrasound energy elastic limit for the particles is reached. Selenium and arsenic are bound differently within the rock lattice because no selenium was detected in the acid soluble fraction and no arsenic was found in the exchangeable fraction. However, selenium was found in the exchangeable fraction and arsenic was found in the acid soluble fraction. The characterization of coal associated rocks is essential to the design of methodologies and procedures that can be used to control the release of arsenic and selenium from valley fills. Published by Elsevier Ltd.

Hydrothermal-precipitation preparation of CdS@(Er3+:Y3Al5O12/ZrO2) coated composite and sonocatalytic degradation of caffeine.

PubMed

Huang, Yingying; Wang, Guowei; Zhang, Hongbo; Li, Guanshu; Fang, Dawei; Wang, Jun; Song, Youtao

2017-07-01

Here, we reported a novel method to dispose caffeine by means of ultrasound irradiation combinated with CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) coated composite as sonocatalyst. The CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) was synthesized via hydrothermal-precipitation method and then characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and UV-vis diffuse reflectance spectra (DRS). After that, the sonocatalytic degradation of caffeine in aqueous solution was conducted adopting CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) and CdS@ZrO 2 coated composites as sonocatalysts. In addition, some influencing factors such as CdS and ZrO 2 molar proportion, caffeine concentration, ultrasonic irradiation time, sonocatalyst dosage and addition of several inorganic oxidants on sonocatalytic degradation of caffeine were investigated by using UV-vis spectra and gas chromatograph. The experimental results showed that the presence of Er 3+ :Y 3 Al 5 O 12 could effectively improve the sonocatalytic degradation activity of CdS@ZrO 2 . To a certain extent some inorganic oxidants can also enhance sonocatalytic degradation of caffeine in the presence of CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ). The best sonocatalytic degradation ratio (94.00%) of caffeine could be obtained when the conditions of 5.00mg/L caffeine, 1.00g/L prepared CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ), 10.00mmol/LK 2 S 2 O 8 , 180min ultrasonic irradiation (40kHz frequency and 50W output power), 100mL total volume and 25-28°C temperature were adopted. It seems that the method of sonocatalytic degradation caused by CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) displayspotentialadvantages in disposing caffeine. Copyright © 2017 Elsevier B.V. All rights reserved.

Survey of advanced nuclear technologies for potential applications of sonoprocessing.

PubMed

Rubio, Floren; Blandford, Edward D; Bond, Leonard J

2016-09-01

Ultrasonics has been used in many industrial applications for both sensing at low power and processing at higher power. Generally, the high power applications fall within the categories of liquid stream degassing, impurity separation, and sonochemical enhancement of chemical processes. Examples of such industrial applications include metal production, food processing, chemical production, and pharmaceutical production. There are many nuclear process streams that have similar physical and chemical processes to those applications listed above. These nuclear processes could potentially benefit from the use of high-power ultrasonics. There are also potential benefits to applying these techniques in advanced nuclear fuel cycle processes, and these benefits have not been fully investigated. Currently the dominant use of ultrasonic technology in the nuclear industry has been using low power ultrasonics for non-destructive testing/evaluation (NDT/NDE), where it is primarily used for inspections and for characterizing material degradation. Because there has been very little consideration given to how sonoprocessing can potentially improve efficiency and add value to important process streams throughout the nuclear fuel cycle, there are numerous opportunities for improvement in current and future nuclear technologies. In this paper, the relevant fundamental theory underlying sonoprocessing is highlighted, and some potential applications to advanced nuclear technologies throughout the nuclear fuel cycle are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Real-time Monitoring Of Damage Evolution In Aerospace Materials Using Nonlinear Acoustics

NASA Astrophysics Data System (ADS)

Matikas, T. E.; Paipetis, A.; Kostopoulos, V.

2008-06-01

This work deals with the development of a novel non-destructive technique based on nonlinear acoustics, enabling real-time monitoring of material degradation in aerospace structures. When a sinusoidal ultrasonic wave of a given frequency and of sufficient amplitude is introduced into a nonlinear or an-harmonic solid, the fundamental wave distorts as it propagates, so that the second and higher harmonics of the fundamental frequency are generated. The measurement of the amplitude of these harmonics provides information on the coefficient of the second and higher order terms of the stress-strain relation for a nonlinear solid. It is demonstrated here that the material bulk nonlinear parameter for titanium alloy samples at different fatigue levels exhibits large changes compared to linear ultrasonic parameters such as velocity and attenuation. However, the use of bulk ultrasonic waves has serious disadvantages for the health monitoring of aerospace structures since it requires the placement of ultrasonic transducers on two, perfectly parallel, opposite sides of the samples. Such a setup is hardly feasible in real field conditions. For this reason, surface acoustic waves (SAW) were used in this study enabling the in-situ characterization of fatigue damage. The experimental setup for measuring the material nonlinear parameter using SAW was realised and the feasibility of the technique for health monitoring of aerospace structures was evaluated.

Degradation of acrylamide by the UV/chlorine advanced oxidation process.

PubMed

Gao, Ze-Chen; Lin, Yi-Li; Xu, Bin; Pan, Yang; Xia, Sheng-Ji; Gao, Nai-Yun; Zhang, Tian-Yang; Chen, Ming

2017-11-01

The degradation of acrylamide (AA) during UV/chlorine advanced oxidation process (AOP) was investigated in this study. The degradation of AA was negligible during UV irradiation alone. However, AA could be effectively degraded and mineralized during UV/chlorination due to the generation of hydroxyl radicals (OH). The degradation kinetics of AA during UV/chlorination fitted the pseudo-first order kinetics with the rate constant between AA and OH radicals being determined as 2.11 × 10 9  M -1  s -1 . The degradation rate and mineralization of AA during UV/chlorination were significantly promoted at acidic conditions as well as increasing chlorine dosage. The volatile degradation products of AA during UV/chlorination were identified using gas chromatography-mass spectrometry and the degradation pathways were then proposed accordingly. The formation of disinfection by-products (DBPs) in Milli-Q water and tap water during UV/chlorination of AA was also investigated. The DBPs included chloroform, dichloroacetonitrile, trichloroacetonitrile, 2,2-dichloroacetamide and 2,2,2-trichloroacetamide. Furthermore, the variations of AA degradation during UV/chlorination in different real water samples were evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative study of ultrasonication, Fenton's oxidation and ferro-sonication treatment for degradation of carbamazepine from wastewater and toxicity test by Yeast Estrogen Screen (YES) assay.

PubMed

Mohapatra, D P; Brar, S K; Tyagi, R D; Picard, P; Surampalli, R Y

2013-03-01

A comparative study of ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) (combination of ultrasonication and Fenton's oxidation) advanced oxidation processes (AOPs) for degradation of carbamazepine (CBZ) from wastewater (WW) is reported for the first time. CBZ is a worldwide used antiepileptic drug, found as a persistent emerging contaminant in many wastewater treatment plants (WWTPs) effluents and other aquatic environments. The oxidation treatments of WW caused an effective removal of the drug. Among the various US, FO and FS pre-treatments carried out, higher soluble chemical oxygen demand (SCOD) and soluble organic carbon (SOC) increment (63 to 86% and 21 to 34%, respectively) was observed during FO pre-treatment process, resulting in higher removal of CBZ (84 to 100%) from WW. Furthermore, analysis of by-products formed during US, FO and FS pre-treatment in WW was carried out by using laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to tandem mass spectrometry (MS/MS). LDTD-APCI-MS/MS analysis indicated formation of two by-products, such as epoxycarbamazepine and hydroxycarbamazepine due to the reaction of hydroxyl radicals (OH) with CBZ during the three types of pre-treatment processes. In addition, the estrogenic activity of US, FO and FS pre-treated sample with CBZ and its by-products was carried out by Yeast Estrogen Screen (YES) assay method. Based upon the YES test results, none of the pre-treated samples showed estrogenic activity. Copyright © 2012 Elsevier B.V. All rights reserved.

Degradation of Chloronitrobenzenes by a Coculture of Pseudomonas putida and a Rhodococcus sp.

PubMed Central

Park, Hee-Sung; Lim, Sung-Jin; Chang, Young Keun; Livingston, Andrew G.; Kim, Hak-Sung

1999-01-01

A single microorganism able to mineralize chloronitrobenzenes (CNBs) has not been reported, and degradation of CNBs by coculture of two microbial strains was attempted. Pseudomonas putida HS12 was first isolated by analogue enrichment culture using nitrobenzene (NB) as the substrate, and this strain was observed to possess a partial reductive pathway for the degradation of NB. From high-performance liquid chromatography-mass spectrometry and 1H nuclear magnetic resonance analyses, NB-grown cells of P. putida HS12 were found to convert 3- and 4-CNBs to the corresponding 5- and 4-chloro-2-hydroxyacetanilides, respectively, by partial reduction and subsequent acetylation. For the degradation of CNBs, Rhodococcus sp. strain HS51, which degrades 4- and 5-chloro-2-hydroxyacetanilides, was isolated and combined with P. putida HS12 to give a coculture. This coculture was confirmed to mineralize 3- and 4-CNBs in the presence of an additional carbon source. A degradation pathway for 3- and 4-CNBs by the two isolated strains was also proposed. PMID:10049867

Degradation of Potassium Rock by Earthworms and Responses of Bacterial Communities in Its Gut and Surrounding Substrates after Being Fed with Mineral

PubMed Central

Liu, Dianfeng; Lian, Bin; Wang, Bin; Jiang, Guofang

2011-01-01

Background Earthworms are an ecosystem's engineers, contributing to a wide range of nutrient cycling and geochemical processes in the ecosystem. Their activities can increase rates of silicate mineral weathering. Their intestinal microbes usually are thought to be one of the key drivers of mineral degradation mediated by earthworms,but the diversities of the intestinal microorganisms which were relevant with mineral weathering are unclear. Methodology/Principal Findings In this report, we show earthworms' effect on silicate mineral weathering and the responses of bacterial communities in their gut and surrounding substrates after being fed with potassium-bearing rock powder (PBRP). Determination of water-soluble and HNO3-extractable elements indicated some elements such as Al, Fe and Ca were significantly released from mineral upon the digestion of earthworms. The microbial communities in earthworms' gut and the surrounding substrates were investigated by amplified ribosomal DNA restriction analysis (ARDRA) and the results showed a higher bacterial diversity in the guts of the earthworms fed with PBRP and the PBRP after being fed to earthworms. UPGMA dendrogram with unweighted UniFrac analysis, considering only taxa that are present, revealed that earthworms' gut and their surrounding substrate shared similar microbiota. UPGMA dendrogram with weighted UniFrac, considering the relative abundance of microbial lineages, showed the two samples from surrounding substrate and the two samples from earthworms' gut had similarity in microbial community, respectively. Conclusions/Significance Our results indicated earthworms can accelerate degradation of silicate mineral. Earthworms play an important role in ecosystem processe since they not only have some positive effects on soil structure, but also promote nutrient cycling of ecosystem by enhancing the weathering of minerals. PMID:22174903

Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254nm/H2O2.

PubMed

Abdelraheem, Wael H M; He, Xuexiang; Duan, Xiaodi; Dionysiou, Dionysios D

2015-01-23

Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254nm/H2O2 advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0mM [H2O2]0, a complete removal of 40.0μM parent PBSA and 25% decrease in TOC were achieved with 190min of UV irradiation; SO4(2-) was formed and reached its maximum level while the release of nitrogen as NH4(+) was much lower (around 50%) at 190min. Sulfate removal was strongly enhanced by increasing [H2O2]0 in the range of 0-4.0mM, with slight inhibition in 4.0-12.0mM. Faster and earlier ammonia formation was observed at higher [H2O2]0. The presence of Br(-) slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl(-). Our study provides important technical and fundamental results on the HO based degradation and mineralization of SO3H and N-containing UV absorber compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes.

PubMed

da Silva, Salatiel Wohlmuth; Klauck, Cláudia Regina; Siqueira, Marco Antônio; Bernardes, Andréa Moura

2015-01-23

Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis - HP, eletrochemical oxidation - EO and photo-assisted electrochemical oxidation - PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250W lamp and a current density of 10mA/cm(2) showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources. Copyright © 2014 Elsevier B.V. All rights reserved.

Kinetics of degradation of surfactant-solubilized fluoranthene by a Sphingomonas paucimobilis

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

Willumsen, P.A.; Arvin, E.

To achieve a better quantitative understanding of the stimulating or inhibiting effect of surfactants on the metabolism of polycyclic aromatic hydrocarbons (PAHs), a biodegradation model describing solubilization, bioavailability, and biodegradation of crystalline fluoranthene is proposed and used to model experimental data. The degradation was investigated in batch systems containing the PAH-degrading bacterium Sphingomonas paucimobilis strain EPA505, the nonionic surfactant Triton X-100, and a fluoranthene-amended liquid mineral salts medium. Surfactant-enhanced biodegradation is complex; however, the biodegradation model predicted fluoranthene disappearance and the initial mineralization well. Surfactant-amendment did increase fluoranthene mineralization rates by strain EPA505; however, the increases were not proportional tomore » the rates of fluoranthene solubilization. The surfactant clearly influenced the microbial PAH metabolism as indicated by a rapid accumulation of colored products and by a surfactant -related decreased in the overall extent of fluoranthene mineralization. Model estimations of the bioavailability of micelle-solubilized fluoranthene, the relatively fast fluoranthene disappearance, and the accumulation of extracellular compounds in the degradation system suggest that low availability of micellar fluoranthene is not the only factor controlling surfactant-enhanced biodegradation. Also factors such as the extent of accumulation and bioavailability of the PAH metabolites and the crystalline solubilization rate in the presence of surfactants may determine the overall effect of surfactant-enhanced biodegradation of high molecular weight PAHs.« less

Modeling of Phenoxy Acid Herbicide Mineralization and Growth of Microbial Degraders in 15 Soils Monitored by Quantitative Real-Time PCR of the Functional tfdA Gene

PubMed Central

Bælum, Jacob; Prestat, Emmanuel; David, Maude M.; Strobel, Bjarne W.

2012-01-01

Mineralization potentials, rates, and kinetics of the three phenoxy acid (PA) herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), were investigated and compared in 15 soils collected from five continents. The mineralization patterns were fitted by zero/linear or exponential growth forms of the three-half-order models and by logarithmic (log), first-order, or zero-order kinetic models. Prior and subsequent to the mineralization event, tfdA genes were quantified using real-time PCR to estimate the genetic potential for degrading PA in the soils. In 25 of the 45 mineralization scenarios, ∼60% mineralization was observed within 118 days. Elevated concentrations of tfdA in the range 1 × 105 to 5 × 107 gene copies g−1 of soil were observed in soils where mineralization could be described by using growth-linked kinetic models. A clear trend was observed that the mineralization rates of the three PAs occurred in the order 2,4-D > MCPA > MCPP, and a correlation was observed between rapid mineralization and soils exposed to PA previously. Finally, for 2,4-D mineralization, all seven mineralization patterns which were best fitted by the exponential model yielded a higher tfdA gene potential after mineralization had occurred than the three mineralization patterns best fitted by the Lin model. PMID:22635998

Effect of ultrasonic agitation on push-out bond strength and adaptation of root-end filling materials

PubMed Central

2018-01-01

Objectives This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Materials and Methods Sixty maxillary canines were divided into 6 groups (n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Results Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA (p < 0.05). US improved the push-out bond strength for all the cements (p < 0.05). Conclusions The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested. PMID:29765903

Effect of ultrasonic agitation on push-out bond strength and adaptation of root-end filling materials.

PubMed

Alcalde, Murilo Priori; Vivan, Rodrigo Ricci; Marciano, Marina Angélica; Duque, Jussaro Alves; Fernandes, Samuel Lucas; Rosseto, Mariana Bailo; Duarte, Marco Antonio Hungaro

2018-05-01

This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Sixty maxillary canines were divided into 6 groups ( n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA ( p < 0.05). US improved the push-out bond strength for all the cements ( p < 0.05). The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested.

An efficient TiO2 coated immobilized system for the degradation studies of herbicide isoproturon: durability studies.

PubMed

Verma, A; Prakash, N T; Toor, A P

2014-08-01

The investigation presents the observations on the use of cement beads for the immobilization of TiO2 for the degradation of herbicide isoproturon. The immobilized system was effective in degrading and mineralizing the herbicide for continuous thirty cycles without losing its durability. Catalyst was characterized by SEM-EDAX for checking the durability of the catalyst. The degradation rate followed first order kinetics as measured by change in absorption intensity in UV range as well as HPLC analysis. Two rounds of TiO2 coating on inert cement beads with average diameter 1.5cm at UV Intensity 25Wm(-2) calcined at 400°C were the optimized conditions for the degradation of herbicide isoproturon. More than 90% TOC and COD reduction along with ammonium ions generation (80%) confirmed the mineralization of isoproturon. Fixed bed baffled reactor studies under solar irradiations using the TiO2 immobilized beads confirmed 85% degradation after 6h. LC-MS studies confirmed the intermediates formation and their subsequent degradation using immobilized system. Copyright © 2014 Elsevier Ltd. All rights reserved.

UV-Vis-Induced Degradation of Phenol over Magnetic Photocatalysts Modified with Pt, Pd, Cu and Au Nanoparticles

PubMed Central

Wysocka, Izabela; Trzciński, Konrad; Łapiński, Marcin; Nowaczyk, Grzegorz; Zielińska-Jurek, Anna

2018-01-01

The combination of TiO2 photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO2 photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO2/SiO2@Fe3O4 nanocomposites were prepared by an ultrasonic-assisted sol-gel method. All prepared samples were characterized by X-ray powder diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), Mott-Schottky analysis and photoluminescence spectroscopy (PL). Phenol oxidation pathways of magnetic photocatalysts modified with Pt, Pd, Cu and Au nanoparticles proceeded by generation of reactive oxygen species, which oxidized phenol to benzoquinone, hydroquinone and catechol. Benzoquinone and maleic acid were products, which were determined in the hydroquinone oxidation pathway. The highest mineralization rate was observed for Pd-TiO2/SiO2@Fe3O4 and Cu-TiO2/SiO2@Fe3O4 photocatalysts, which produced the highest concentration of catechol during photocatalytic reaction. For Pt-TiO2/SiO2@Fe3O4 nanocomposite, a lack of catechol after 60 min of irradiation resulted in low mineralization rate (CO2 formation). It is proposed that the enhanced photocatalytic activity of palladium and copper-modified photocatalysts is related to an increase in the amount of adsorption sites and efficient charge carrier separation, whereas the keto-enol tautomeric equilibrium retards the rate of phenol photomineralization on Au-TiO2/SiO2@Fe3O4. The magnetization hysteresis loop indicated that the obtained hybrid photocatalyst showed magnetic properties and therefore could be easily separated after treatment process. PMID:29316667

Interactions between glycine derivatives and mineral surfaces: Implications for the origins of life on planetary surfaces

NASA Astrophysics Data System (ADS)

Marshall-Bowman, K. J.; Cleaves, H. J.; Sverjensky, D. A.; Hazen, R. M.

2009-12-01

Various mechanisms could have delivered amino acids to the prebiotic Earth (Miller and Orgel 1974). The polymerization of amino acids may have been important for the origin of life, as peptides may have been components for the first self-replicating systems (Kauffman 1971; Yao et al 1998). Though amino acid concentrations in the primitive oceans were likely too dilute for significant oligomerization to occur (Cleaves et al 2009), mineral surface adsorption may have concentrated these biomolecules (Bernal 1951; Lambert 2008). Few studies have examined the catalytic effects of mineral surfaces on aqueous peptide oligomerization or degradation. As unactivated amino acid polymerization is thermodynamically unfavorable and kinetically slow in aqueous solution, we studied the reverse reaction of polymer degradation to measure potential mineral catalysis. Glycine (G) derivatives glycylglycine (GG), diketopiperazine (DKP), and glycylglycylglycine (GGG) were reacted with different minerals (calcite, hematite, montmorillonite, rutile, amorphous silica, and pyrite) in the presence of 0.05 M pH 8.1 KHCO3 buffer and 0.1 M NaCl as background electrolyte. Experiments were performed by reacting the aqueous amino acid derivative-mineral mixtures in a thermostatted oven (modified to accommodate a mechanical rotator) at 25°, 50° or 70°C. Samples were removed after 30, 60, 90, and 140 hours. Samples were then analyzed using high performance liquid chromatography to quantify the products. Besides mineral catalysis, it was determined that degradation of GGG proceeds principally via a GGG → DKP + G mechanism, rather than via GGG → GG + G. Below 70°C kinetics were generally too sluggish to detect catalytic activity over reasonable laboratory time-scales at this pH. At 70°C, pyrite was the only mineral with detectible catalytic effects on the degradation of GGG. GGG degraded ~ 1.5 - 4 x faster in the presence of pyrite than in control reactions, depending on the ratio of solution to mineral surface area. Catalysis was found to be saturable, suggesting the presence of discrete catalytic sites on the mineral surface. These and other results will be presented and discussed. References Bernal, J. D. (1951) The Physical Basis of Life (Routledge, London). Cleaves, H.J., Aubrey, A.D., Bada, J.L. (2009) An evaluation of the critical parameters for abiotic peptide synthesis in submarine hydrothermal systems. Origins of Life Evol Biosph. 39:109-26. Kauffman, S.A. (1971) Cellular homeostasis, epigenesis and replication in randomly aggregated macromolecular systems. Cybernetics and Systems: An International Journal 1: 71 - 96. Lambert, J. (2008) Adsorption and polymerization of amino acids on mineral surfaces: A review. Origins of Life Evol. Biosph. 38: 211-42. Miller, S.L. and Orgel, L.E. (1974) The Origins of Life on the Earth, Prentice Hall (Englewood Cliffs, NJ) Yao, Y., Ghosh, I., Zutshi, R., Chmielewski, J. (1998) Selective amplification by auto- and cross-catalysis in a replicating peptide system. Nature 396, 447 - 450.

Sonocatalytical degradation enhancement for ibuprofen and sulfamethoxazole in the presence of glass beads and single-walled carbon nanotubes.

PubMed

Al-Hamadani, Yasir A J; Chu, Kyoung Hoon; Flora, Joseph R V; Kim, Do-Hyung; Jang, Min; Sohn, Jinsik; Joo, Wanho; Yoon, Yeomin

2016-09-01

Sonocatalytic degradation experiments were carried out to determine the effects of glass beads (GBs) and single-walled carbon nanotubes (SWNTs) on ibuprofen (IBP) and sulfamethoxazole (SMX) removal using low and high ultrasonic frequencies (28 and 1000kHz). In the absence of catalysts, the sonochemical degradation at pH 7, optimum power of 0.18WmL(-1), and a temperature of 15°C was higher (79% and 72%) at 1000kHz than at 28kHz (45% and 33%) for IBP and SMX, respectively. At the low frequency (28kHz) H2O2 production increased significantly, from 10μM (no GBs) to 86μM in the presence of GBs (0.1mm, 10gL(-1)); however, no enhancement was achieved at 1000kHz. In contrast, the H2O2 production increased from 10μM (no SWNTs) to 31μM at 28kHz and from 82μM (no SWNTs) to 111μM at 1000kHz in the presence of SWNTs (45mgL(-1)). Thus, maximum removals of IBP and SMX were obtained in the presence of a combination of GBs and SWNTs at the low frequency (94% and 88%) for 60min contact time; however, >99% and 97% removals were achieved for 40 and 60min contact times at the high frequency for IBP and SMX, respectively. The results indicate that both IBP and SMX degradation followed pseudo-first-order kinetics. Additionally, the enhanced removal of IBP and SMX in the presence of catalysts was because GBs and SWNTs increased the number of free OH radicals due to ultrasonic irradiation and the adsorption capacity increase with SWNT dispersion. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel approaches based on ultrasound for treatment of wastewater containing potassium ferrocyanide.

PubMed

Jawale, Rajashree H; Tandale, Akash; Gogate, Parag R

2017-09-01

Industrial wastewaters containing biorefractory compounds like cyanide offer significant environmental problems attributed to the fact that the conventional methods have limited effectiveness and hence developing efficient treatment approaches is an important requirement. The present work investigates the use of novel treatment approach of ultrasound (US) combined with advanced oxidation techniques for the degradation of potassium ferrocyanide (KFC) for the first time. An ultrasonic bath equipped with longitudinal horn (1kW rated power and 25kHz frequency) has been used. The effect of initial pH (2-9) on the progress of degradation has been investigated initially and subsequently using the optimized pH, effect of addition of hydrogen peroxide (ratio of KFC:H 2 O 2 varied over the range of 1:0.5-1:5) and TiO 2 in the presence of H 2 O 2 (1:1 ratio by weight of TiO 2 ) as process intensifying approach has been studied. Combination of ultrasonic irradiation with ozone (O 3 ) (100-400mg/h) and ultraviolet irradiation (UV) has also been investigated. Use of combination of US with H 2 O 2, H 2 O 2 +TiO 2 and ozone resulted in extent of KFC degradation as 54.2%, 74.82% and 82.41% respectively. Combination of US with both UV and ozone was established to be the best approach yielding 92.47% degradation. The study also focused on establishing kinetic rate constants for all the treatment approaches which revealed that all the approaches followed first order kinetic mechanism with higher rate constants for the combination approaches. Overall, it has been conclusively established that ultrasound based combined treatment schemes are very effective for the treatment of KFC containing wastewaters. Copyright © 2017 Elsevier B.V. All rights reserved.

Fate of organo-mineral particles in streams: Microbial degradation by streamwater & biofilm assemblages

NASA Astrophysics Data System (ADS)

Hunter, W. R.; Raich, M.; Wanek, W.; Battin, T. J.

2013-12-01

Inland waters are of global biogeochemical importance. They receive carbon inputs of ~ 4.8 Pg C/ y of which, 12 % is buried, 18 % transported to the oceans, and 70 % supports aquatic secondary production. However, the mechanisms that determine the fate of organic matter (OM) in these systems are poorly defined. One aspect of this is the formation of organo-mineral complexes in aquatic systems and their potential as a route for OM transport and burial vs. their use as carbon (C) and nitrogen (N) sources within aquatic systems. Organo-mineral particles form by sorption of dissolved OM to freshly eroded mineral surfaces and may contribute to ecosystem-scale particulate OM fluxes. We experimentally tested the availability of mineral-sorbed OM as a C & N source for streamwater microbial assemblages and streambed biofilms. Organo-mineral particles were constructed in vitro by sorption of 13C:15N-labelled amino acids to hydrated kaolin particles, and microbial degradation of these particles compared with equivalent doses of 13C:15N-labelled free amino acids. Experiments were conducted in 120 ml mesocosms over 7 days using biofilms and water sampled from the Oberer Seebach stream (Austria). Each incubation experienced a 16:8 light:dark regime, with metabolism monitored via changes in oxygen concentrations between photoperiods. The relative fate of the organo-mineral particles was quantified by tracing the mineralization of the 13C and 15N labels and their incorporation into microbial biomass. Here we present the initial results of 13C-label mineralization, incorporation and retention within dissolved organic carbon pool. The results indicate that 514 (× 219) μmol/ mmol of the 13:15N labeled free amino acids were mineralized over the 7-day incubations. By contrast, 186 (× 97) μmol/ mmol of the mineral-sorbed amino acids were mineralized over a similar period. Thus, organo-mineral complexation reduced amino acid mineralization by ~ 60 %, with no differences observed between the streamwater and biofilm assemblages. Throughout the incubations, biofilms were observed to leach dissolved organic carbon (DOC). However, within the streamwater assemblage the presence of both organo-mineral particles and kaolin particles was associated with significant DOC removal (-1.7 % and -7.5 % respectively). Consequently, the study demonstrates that mineral and organo-mineral particles can limit the availability of DOC in aquatic systems, providing nucleation sites for flocculation and fresh mineral surfaces, which facilitate OM-sorption. The formation of these organo-mineral particles subsequently restricts microbial OM degradation, potentially altering the transport and facilitating the burial of OM within streams.

Direct degradation of dyes by piezoelectric fibers through scavenging low frequency vibration

NASA Astrophysics Data System (ADS)

Zhu, Ruijian; Xu, Yunhua; Bai, Qing; Wang, Zengmei; Guo, Xinli; Kimura, Hideo

2018-06-01

A newly discovered nanometer material-mediated piezoelectrochemical (PZEC) for the direct conversion of mechanical energy to chemical energy has attracted increasing attention, for its great potential to be a green dye water decomposition technique. However, it is far from being a cost-effective and practical technique because only ultrasonic can be scavenged to decomposed organic pollutant in previous studies. Here, we prepared 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) piezoelectric fibers for the degradation of dye solution via slow stirring and studied the degradation mechanism. It provides a practical, green and low-cost method for decomposing organic dye by scavenging waste mechanical energy from the surrounding environment.

Dynamic Characteristics of Green Sandstone Subjected to Repetitive Impact Loading: Phenomena and Mechanisms

NASA Astrophysics Data System (ADS)

Li, S. H.; Zhu, W. C.; Niu, L. L.; Yu, M.; Chen, C. F.

2018-06-01

A split Hopkinson pressure bar apparatus driven by a pendulum hammer was used to perform uniaxial compression tests to examine the degradation process of green sandstone subjected to repetitive impact loading. The acoustic characteristics, dissipated energy, deformation characteristics, and microstructure evolution were investigated. The representative stress-strain curve can be broken into five stages that were characterized by changes in the axial strain response during impact loading. Both the ultrasonic wave velocity and cumulative dissipated energy exhibited obvious three-stage behavior with respect to the impact number. As the impact number increased, more than one peak was observed in the frequency spectra, and the relative weight of the peak frequency increased in the low-frequency range. According to the evolution of the ultrasonic wave velocity, the degradation process was divided into three stages. By comparing the intact stage I and early stage II microcrack development patterns, the initiation of new cracks and elongation of existing cracks were identified as the main degradation mechanisms. Furthermore, a slight increase in the number of cracks was observed, and microcrack lengths steadily increased. Moreover, due to the low level of microcrack damage, the deformation mechanism was mainly characterized by volume compression during impact loading. In late stage II, the main degradation mechanism was the elongation of existing cracks. Additionally, as microcracks accumulated in the rock samples, cracks were arranged parallel to the loading direction, which led to volume dilation. In stage III, microcracks continued to elongate nearly parallel to the loading direction and then linked to each other, which led to intense degradation in the rock samples. In this stage, rock sample deformation was mainly characterized by volume dilation during impact loading. Finally, rock samples were split into blocks with fractures oriented subparallel to the loading direction. These results can improve the understanding of the stability evaluations of rock structures subjected to repetitive impact loading.

Aerobic mineralization of vinyl chlorides by a bacterium of the order Actinomycetales

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

Phelps, T.J.; Malachowsky, K.; Schram, R.M.

1991-04-01

A gram-positive branched bacterium isolated from a trichloroethylene-degrading consortium mineralized vinyl chloride in growing cultures and cell suspensions. Greater than 67% of the (1,2-{sup 14}C)vinyl chloride was mineralized to carbon dioxide, with approximately 10% of the radioactivity appearing in {sup 14}C-aqueous-phase products.

Experimental Investigation of the Acoustic Nonlinear Behavior in Granular Polymer Bonded Explosives with Progressive Fatigue Damage

PubMed Central

Yang, Zhanfeng; Tian, Yong; Li, Weibin; Zhou, Haiqiang; Zhang, Weibin; Li, Jingming

2017-01-01

The measurement of acoustic nonlinear response is known as a promising technique to characterize material micro-damages. In this paper, nonlinear ultrasonic approach is used to characterize the evolution of fatigue induced micro-cracks in polymer bonded explosives. The variations of acoustic nonlinearity with respect to fatigue cycles in the specimens are obtained in this investigation. The present results show a significant increase of acoustic nonlinearity with respect to fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and fatigue cycles in carbon/epoxy laminates, verifies that an acoustic nonlinear response can be used to evaluate the progressive fatigue damage in the granular polymer bonded explosives. The sensitivity comparison of nonlinear and linear parameters of ultrasonic waves in the specimens shows that nonlinear acoustic parameters are more promising indicators to fatigue induced micro-damage than linear ones. The feasibility study of the micro-damage assessment of polymer bonded explosives by nonlinear ultrasonic technique in this work can be applied to damage identification, material degradation monitoring, and lifetime prediction of the explosive parts. PMID:28773017

Experimental Investigation of the Acoustic Nonlinear Behavior in Granular Polymer Bonded Explosives with Progressive Fatigue Damage.

PubMed

Yang, Zhanfeng; Tian, Yong; Li, Weibin; Zhou, Haiqiang; Zhang, Weibin; Li, Jingming

2017-06-16

The measurement of acoustic nonlinear response is known as a promising technique to characterize material micro-damages. In this paper, nonlinear ultrasonic approach is used to characterize the evolution of fatigue induced micro-cracks in polymer bonded explosives. The variations of acoustic nonlinearity with respect to fatigue cycles in the specimens are obtained in this investigation. The present results show a significant increase of acoustic nonlinearity with respect to fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and fatigue cycles in carbon/epoxy laminates, verifies that an acoustic nonlinear response can be used to evaluate the progressive fatigue damage in the granular polymer bonded explosives. The sensitivity comparison of nonlinear and linear parameters of ultrasonic waves in the specimens shows that nonlinear acoustic parameters are more promising indicators to fatigue induced micro-damage than linear ones. The feasibility study of the micro-damage assessment of polymer bonded explosives by nonlinear ultrasonic technique in this work can be applied to damage identification, material degradation monitoring, and lifetime prediction of the explosive parts.

Potential for Microbial Degradation of cis-Dichloroethene and Vinyl Chloride in Streambed Sediment at the U.S. Department of Energy, Kansas City Plant, Missouri, 2008

USGS Publications Warehouse

Bradley, Paul M.

2009-01-01

A series of carbon-14 (14C) radiotracer-based microcosm experiments was conducted to assess the mechanisms and products of degradation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) in streambed sediments at the U.S. Department of Energy, Kansas City Plant in Kansas City, Missouri. The focus of the investigation was the potential for biotic and abiotic cis-DCE and VC degradation in surficial and underlying hyporheic sediment from the Blue River and its tributaries, Indian Creek and Boone Creek. Substantial degradation of [1,2-14C] cis-DCE and [1,2-14C] VC to 14C-carbon dioxide (14CO2) was observed in all viable surficial sediment microcosms prepared under oxic conditions. No significant accumulation of reductive dechlorination products was observed under these oxic incubation conditions. The results indicate that microbial mineralization processes involving direct oxidation or co-metabolic oxidation are the primary mechanisms of cis-DCE and VC biodegradation in oxic stream sediment at the Kansas City Plant. Substantial mineralization of [1,2-14C] VC also was observed in all viable surficial sediment microcosms incubated in the absence of detectable oxygen (dissolved oxygen concentrations less than 25 micrograms per liter). In general, the accumulation of mineralization products (14CO2 and 14C-methane [14CH4]) predominated with only trace-level detection of the reductive dechlorination product, 14C-ethene. In contrast, microbial degradation of [1,2-14C] cis-DCE by reductive dechlorination or mineralization was not significant in the absence of detectable oxygen. The potential for [1,2-14C] VC biodegradation also was significant in sediments from the deeper hyporheic zones under oxic conditions and in the absence of detectable oxygen. In this study, microbial degradation of [1,2-14C] cis-DCE was not significant in hyporheic sediment treatments under either oxygen condition. Taken together, the results indicate that microbial mineralization processes in streambed sediments at the Kansas City Plant can be an important component of cis-DCE and VC degradation under oxic conditions and of VC degradation even in the absence of detectable oxygen. These results demonstrate that an evaluation of the efficiency of in situ cis-DCE and VC biodegradation in streambed sediments, based solely on observed accumulations of reduced daughter products, may underestimate substantially the total extent of contaminant biodegradation and, thus, the potential importance of the hyporheic zone and streambed sediments as barriers to the discharge of contaminated groundwater.

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.

Resolution Enhancement In Ultrasonic Imaging By A Time-Varying Filter

NASA Astrophysics Data System (ADS)

Ching, N. H.; Rosenfeld, D.; Braun, M.

1987-09-01

The study reported here investigates the use of a time-varying filter to compensate for the spreading of ultrasonic pulses due to the frequency dependence of attenuation by tissues. The effect of this pulse spreading is to degrade progressively the axial resolution with increasing depth. The form of compensation required to correct for this effect is impossible to realize exactly. A novel time-varying filter utilizing a bank of bandpass filters is proposed as a realizable approximation of the required compensation. The performance of this filter is evaluated by means of a computer simulation. The limits of its application are discussed. Apart from improving the axial resolution, and hence the accuracy of axial measurements, the compensating filter could be used in implementing tissue characterization algorithms based on attenuation data.

Biodegradation of ddt (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) by the white rot fungus phanerochaete chrysosporium

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

Bumpus, J.A.; Aust, S.D.

1987-01-01

Extensive biodegradation of 1,1,1-trichloro-2,2bis(4-chlorophenyl)ethane (DDT) by the white rot fungus Phanerochaete chrysosporium was demonstrated by disappearance and mineralization of (14C) DDT in nutrient nitrogen-deficient cultures. Mass balance studies demonstrated the formation of polar and water-soluble metabolites during degradation. Hexane-extractable metabolites identified by gas chromatography-mass spectrometry included 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane(DDD), 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol), 2,2-dichloro-1,1-bis(4-chlorophenyl) ethanol (FW-152), and 4,4'-dichlorobenzophenone (DBP). DDD was the first metabolite observed; it appeared after 3 days of incubation and disappeared from culture upon continued incubation. This, as well as the fact that ((14)C) dicofol was mineralized, demonstrates that intermediates formed during DDT degradation are also metabolized. These results demonstrate thatmore » the pathway for DDT degradation in P. chrysosporium is clearly different from the major pathway proposed for microbial or environmental degradation of DDT. Like P. chrysosporium ME-446 and BKM-F-1767, the white rot fungi Pleurotus ostreatus, Phellinus weirii, and Polyporus versicolor also mineralized DDT.« less

Effects of ultrasonic disintegration of excess sewage sludge.

PubMed

Zielewicz, Ewa

2016-10-01

Breaking down sludge floc (sonodyspergation effect) and destruction of the cell membranes of microorganisms forming floc is a direct effect of ultrasonic disintegration of sludge excess. This results in release of organic material by liquid sludge (the sonolysis effect). Desired technological effects of the disintegration are: to shorten the hydrolytic phase of fermentation, to increase the production of biogas (source of renewable energy) and an increased mineralization (stability) of fermented sludge. The presented study demonstrates research covering thickened excess sludge of various physicochemical properties, collected from nine municipal sewage treatment plants. The sludge was subjected to ultrasonic disintegration using three differently constructed disintegrators and different proportions of sonification area. Direct effects of disintegration were monitored and recorded using selected indicators describing changes in the properties of sludge and increase of substance dispersed and dissolved in the supernatant liquid to be filtered. Studies have demonstrated that those (direct) effects of ultrasonic disintegration depend on the physicochemical properties of the sludge (foremost the concentration of dry solids) that determine their variable susceptibility to the disintegration methods. The direct effects also depend on optimal process conditions (which consist of the construction of the ultrasonic disintegrator), the geometric proportions of the sonication area and the operating parameters of disintegration (which could be appropriately matched to the characteristics of sludge). The most preferable results were obtained for ultrasonic disintegration of sludge with a dry matter concentration C 0 < 4.2 %. The highest effect of sonolysis-an almost 30-fold increase in the COD dissolved in the supernatant-was obtained for the sludge of lowest dry matter (C 0 = 2.0 %), which was sonicated in a reactor with a short transducer of the largest radiating surface area, as well as the lowest ratio between this area and area of reactor. The best effects of disagglomeration of flocks have corresponded with the high value of power density U UD = 880-900 WL(-1).

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted maleic anhydride (MA) affected mechanical properties and oxygen permeability with ultrasonic treatment to higher extent. However, use of compatibilizers led to a higher die pressure and resulted in opaque cast films. The mechanical properties were in agreement with crystallinity of samples. The exfoliated structure was achieved for PA6/clay 30B nanocomposites prepared using ultrasonically assisted single screw extrusion except for untreated nanocomposites containing 10 wt% of clay 30B. Untreated 92.5/7.5 and 90/10 PA6/clay 30B blown films showed the intercalated structure, but the exfoliated structure was achieved with ultrasonic treatment. All cast films of PA6/clay 30B showed the exfoliated structure. FTIR spectroscopy along with XRD results confirmed the existence of alpha and gamma-type crystals in the cast films, with clay particles favoring the formation of gamma-type crystals, and ultrasonic treatment favoring the formation of alpha-type crystals. Both parameters increased crystallinity of cast films improving their mechanical properties and oxygen permeability.

Effect of soil metal contamination on glyphosate mineralization: role of zinc in the mineralization rates of two copper-spiked mineral soils.

PubMed

Kim, Bojeong; Kim, Young Sik; Kim, Bo Min; Hay, Anthony G; McBride, Murray B

2011-03-01

A systematic investigation into lowered degradation rates of glyphosate in metal-contaminated soils was performed by measuring mineralization of [(14)C]glyphosate to (14)CO(2) in two mineral soils that had been spiked with Cu and/or Zn at various loadings. Cumulative (14)CO(2) release was estimated to be approximately 6% or less of the amount of [(14)C]glyphosate originally added in both soils over an 80-d incubation. For all but the highest Cu treatments (400 mg kg(-1)) in the coarse-textured Arkport soil, mineralization began without a lag phase and declined over time. No inhibition of mineralization was observed for Zn up to 400 mg kg(-1) in either soil, suggesting differential sensitivity of glyphosate mineralization to the types of metal and soil. Interestingly, Zn appeared to alleviate high-Cu inhibition of mineralization in the Arkport soil. The protective role of Zn against Cu toxicity was also observed in the pure culture study with Pseudomonas aeruginosa, suggesting that increased mineralization rates in high Cu soil with Zn additions might have been due to alleviation of cellular toxicity by Zn rather than a mineralization specific mechanism. Extensive use of glyphosate combined with its reduced degradation in Cu-contaminated, coarse-textured soils may increase glyphosate persistence in soil and consequently facilitate Cu and glyphosate mobilization in the soil environment. Copyright © 2010 SETAC.

Degradation and mineralization of DDT by the ectomycorrhizal fungi, Xerocomus chrysenteron.

PubMed

Huang, Yi; Wang, Jie

2013-08-01

One strain of ectomycorrhizal fungi, Xerocomus chrysenteron, had been investigated for its ability to degrade 1,1,1-trichloro-2,2-bis(4-chlorophe-nyl) ethane (DDT) by measuring unlabeled DDT and identifying its metabolites, and determining the mineralization of [(13)C]DDT in pure cultures. After 45d incubation, about 55% of the added DDT disappeared from the culture system, less than 5% remained in the nutrient solution, and about 44% was retained in the mycelium. Inoculation with mycelium enhanced the degradation of DDT in soil, and alleviated enrichment of DDT in plants. The metabolites identified by gas chromatography-mass spectrometry were 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), and 4,4'-dichlorobenzophenone (DBP). There were significant differences in the δ(13)C of released CO2 between [(13)C]DDT and DDT cultures, which indicated X. chrysenteron was able to mineralize DDT to CO2. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biodegradation of the High Explosive Hexanitrohexaazaiso-wurtzitane (CL-20)

PubMed Central

Karakaya, Pelin; Christodoulatos, Christos; Koutsospyros, Agamemnon; Balas, Wendy; Nicolich, Steve; Sidhoum, Mohammed

2009-01-01

The aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated. Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse conditions. Variables included the CL-20 concentration; levels of carbon (as glycerol) and ammonium sulfate and yeast extract as sources of nitrogen. Cultures that received CL-20 at the time of inoculation transformed CL-20 completely under all nutrient conditions studied. When CL-20 was added to pre-grown cultures, degradation was limited. The extent of mineralization was monitored by the 14CO2 time evolution; up to 51% mineralization was achieved when the fungus was incubated with [14C]-CL-20. The kinetics of CL-20 biodegradation by Phanerochaete chrysosporium follows the logistic kinetic growth model. PMID:19440524

Biodegradation of the high explosive hexanitrohexaazaiso-wurtzitane (CL-20).

PubMed

Karakaya, Pelin; Christodoulatos, Christos; Koutsospyros, Agamemnon; Balas, Wendy; Nicolich, Steve; Sidhoum, Mohammed

2009-04-01

The aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated. Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse conditions. Variables included the CL-20 concentration; levels of carbon (as glycerol) and ammonium sulfate and yeast extract as sources of nitrogen. Cultures that received CL-20 at the time of inoculation transformed CL-20 completely under all nutrient conditions studied. When CL-20 was added to pre-grown cultures, degradation was limited. The extent of mineralization was monitored by the (14)CO(2) time evolution; up to 51% mineralization was achieved when the fungus was incubated with [(14)C]-CL-20. The kinetics of CL-20 biodegradation by Phanerochaete chrysosporium follows the logistic kinetic growth model.

Bioremediation of PAHs and VOCs: Advances in clay mineral-microbial interaction.

PubMed

Biswas, Bhabananda; Sarkar, Binoy; Rusmin, Ruhaida; Naidu, Ravi

2015-12-01

Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of iron (III) minerals and acidification on the reductive dechlorination of trichloroethylene.

PubMed

Paul, Laiby; Smolders, Erik

2014-09-01

Reductive dechlorination of chlorinated ethenes is inhibited by acidification and by the presence of Fe (III) as a competitive electron acceptor. Synergism between both factors on dechlorination is predicted as reductive dissolution of Fe (III) minerals is facilitated by acidification. This study was set-up to assess this synergism for two common aquifer Fe (III) minerals, goethite and ferrihydrite. Anaerobic microbial dechlorination of trichloroethylene (TCE) by KB-1 culture and formate as electron donor was investigated in anaerobic batch containers at different solution pH values (6.2-7.2) in sand coated with these Fe minerals and a sand only as control. In the absence of Fe, lowering substrate pH from 7.2 to 6.2 increased the time for 90% TCE degradation from 14±1d to 42±4d. At pH 7.2, goethite did not affect TCE degradation time while ferrihydrite increased the degradation time to 19±1d compared to the no Fe control. At pH 6.2, 90% degradation was at 78±1 (ferrihydrite) or 131±1d (goethite). Ferrous iron production in ferrihydrite treatment increased between pH 7.2 and 6.5 but decreased by further lowering pH to 6.2, likely due to reduced microbial activity. This study confirms that TCE is increasingly inhibited by the combined effect of acidification and bioavailable Fe (III), however no evidence was found for synergistic inhibition since Fe reduction did not increase as pH decreases. To the best of our knowledge, this is the first study where effect of pH and Fe (III) reduction on TCE was simultaneously tested. Acid Fe-rich aquifers need sufficient buffering and alkalinity to ensure swift degradation of chlorinated ethenes. Copyright © 2014. Published by Elsevier Ltd.

Elastic anisotropy of layered rocks: Ultrasonic measurements of plagioclase-biotite-muscovite (sillimanite) gneiss versus texture-based theoretical predictions (effective media modeling)

NASA Astrophysics Data System (ADS)

Ivankina, T. I.; Zel, I. Yu.; Lokajicek, T.; Kern, H.; Lobanov, K. V.; Zharikov, A. V.

2017-08-01

In this paper we present experimental and theoretical studies on a highly anisotropic layered rock sample characterized by alternating layers of biotite and muscovite (retrogressed from sillimanite) and plagioclase and quartz, respectively. We applied two different experimental methods to determine seismic anisotropy at pressures up to 400 MPa: (1) measurement of P- and S-wave phase velocities on a cube in three foliation-related orthogonal directions and (2) measurement of P-wave group velocities on a sphere in 132 directions The combination of the spatial distribution of P-wave velocities on the sphere (converted to phase velocities) with S-wave velocities of three orthogonal structural directions on the cube made it possible to calculate the bulk elastic moduli of the anisotropic rock sample. On the basis of the crystallographic preferred orientations (CPOs) of major minerals obtained by time-of-flight neutron diffraction, effective media modeling was performed using different inclusion methods and averaging procedures. The implementation of a nonlinear approximation of the P-wave velocity-pressure relation was applied to estimate the mineral matrix properties and the orientation distribution of microcracks. Comparison of theoretical calculations of elastic properties of the mineral matrix with those derived from the nonlinear approximation showed discrepancies in elastic moduli and P-wave velocities of about 10%. The observed discrepancies between the effective media modeling and ultrasonic velocity data are a consequence of the inhomogeneous structure of the sample and inability to perform long-wave approximation. Furthermore, small differences between elastic moduli predicted by the different theoretical models, including specific fabric characteristics such as crystallographic texture, grain shape and layering were observed. It is shown that the bulk elastic anisotropy of the sample is basically controlled by the CPO of biotite and muscovite and their volume proportions in the layers dominated by phyllosilicate minerals.

Interactions Between Biogenic Silica (BSiO2) and Organic Carbon (POC) During the Recycling of Sinking Particles

NASA Astrophysics Data System (ADS)

Moriceau, B.; Goutx, M.; Guigue, C.; Tamburini, C.; Lee, C.; Armstrong, R. A.; Duflos, M.; Charriere, B.; Ragueneau, O.

2006-12-01

Despite recent progress in understanding the ocean's role in the global carbon cycle, we are not yet able to predict the response of ecosystems to climate change and feedbacks of the ocean onto atmospheric CO2. In particular, particle flux dynamics must be represented more faithfully in ocean models. We know that particulate organic carbon (POC) flux is associated with ballast minerals (BSiO2, CaCO3), but the processes controlling the interactions between carbon and ballast minerals during decomposition must be explored further. The present study aims to provide a better understanding of interactions between carbon and BSiO2 during mineralization of sinking particles. Previous studies have provided evidence that the degradation of the external membrane by bacteria increase the BSiO2 dissolution rate. Alternatively, it has been hypothesized that biogenic silica could protect carbon from degradation. To test this hypothesis, an in-vitro batch experiment using the diatom Skeletonema costatum was conducted. In this experiment, carbon degradation, bacterial growth, and BSiO2 dissolution were followed simultaneously. To identify the processes involved and the types of carbon that eventually interact with BSiO2 during mineralization, the concentrations of different lipids and amino acids were also measured. A strong increase of the degradation rate constant of the POC and PON was observed after dissolution of 40 % of initial BSiO2. This increase is associated to a peak of glycine in total amino acids and a switch between free and attached bacteria. These results suggest that carbon degradation is increased when enough of the frustule is dissolved to uncover the glycine contain inside the frustule, this amino acid may trigger an increase in the concentration of attached bacteria, which may in turn increase the degradation rate constant of organic carbon.

Degradation potentials of dissolved organic carbon (DOC) from thawed permafrost peat

PubMed Central

Panneer Selvam, Balathandayuthabani; Lapierre, Jean-François; Guillemette, Francois; Voigt, Carolina; Lamprecht, Richard E.; Biasi, Christina; Christensen, Torben R.; Martikainen, Pertti J.; Berggren, Martin

2017-01-01

Global warming can substantially affect the export of dissolved organic carbon (DOC) from peat-permafrost to aquatic systems. The direct degradability of such peat-derived DOC, however, is poorly constrained because previous permafrost thaw studies have mainly addressed mineral soil catchments or DOC pools that have already been processed in surface waters. We incubated peat cores from a palsa mire to compare an active layer and an experimentally thawed permafrost layer with regard to DOC composition and degradation potentials of pore water DOC. Our results show that DOC from the thawed permafrost layer had high initial degradation potentials compared with DOC from the active layer. In fact, the DOC that showed the highest bio- and photo-degradability, respectively, originated in the thawed permafrost layer. Our study sheds new light on the DOC composition of peat-permafrost directly upon thaw and suggests that past estimates of carbon-dioxide emissions from thawed peat permafrost may be biased as they have overlooked the initial mineralization potential of the exported DOC. PMID:28378792

Earth mineral resource of the month: asbestos

USGS Publications Warehouse

Virta, Robert L.

2010-01-01

The article discusses the characteristics and feature of asbestos. According to the author, asbestos is a generic name for six needle-shaped minerals that possess high tensile strengths, flexibility, and resistance to chemical and thermal degradation. These minerals are actinolite, amosite, anthophyllite, chrysolite, crocilodite and tremolite. Asbestos is used for strengthening concrete pipe, plastic components, and gypsum plasters.

Visualizing the Vibration of Laryngeal Tissue during Phonation Using Ultrafast Plane Wave Ultrasonography.

PubMed

Jing, Bowen; Tang, Shanshan; Wu, Liang; Wang, Supin; Wan, Mingxi

2016-12-01

Ultrafast plane wave ultrasonography is employed in this study to visualize the vibration of the larynx and quantify the vibration phase as well as the vibration amplitude of the laryngeal tissue. Ultrasonic images were obtained at 5000 to 10,000 frames/s in the coronal plane at the level of the glottis. Although the image quality degraded when the imaging mode was switched from conventional ultrasonography to ultrafast plane wave ultrasonography, certain anatomic structures such as the vocal folds, as well as the sub- and supraglottic structures, including the false vocal folds, can be identified in the ultrafast plane wave ultrasonic image. The periodic vibration of the vocal fold edge could be visualized in the recorded image sequence during phonation. Furthermore, a motion estimation method was used to quantify the displacement of laryngeal tissue from hundreds of frames of ultrasonic data acquired. Vibratory displacement waveforms of the sub- and supraglottic structures were successfully obtained at a high level of ultrasonic signal correlation. Moreover, statistically significant differences in vibration pattern between the sub- and supraglottic structures were found. Variation of vibration amplitude along the subglottic mucosal surface is significantly smaller than that along the supraglottic mucosal surface. Phase delay of vibration along the subglottic mucosal surface is significantly smaller than that along the supraglottic mucosal surface. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

TiO₂ supported over SBA-15: an efficient photocatalyst for the pesticide degradation using solar light.

PubMed

Phanikrishna Sharma, M V; Durga Kumari, V; Subrahmanyam, M

2008-11-01

Photocatalytic degradation and mineralization of pesticides are studied over TiO(2) supported mesoporous SBA-15 composite system using solar light. TiO(2) is immobilized over SBA-15 by solid sate dispersion method. The catalysts are characterized by XRD, surface area, UV-Vis diffused reflectance spectra, SEM and TEM. The detailed photocatalytic degradation studies are carried out over TiO(2), SBA-15 and different TiO(2) wt% supported SBA-15. The activity evaluation parameters such as catalyst amount, pH, and pollutant initial concentration are studied taking isoproturon as a model compound and established conditions for pesticide degradation. The optimum degradation is achieved over 10 wt% TiO(2)/SBA-15 within 30 min and the reaction is following pseudo-first order kinetics. The isoproturon mineralization is monitored with TOC reduction and it takes around 9h for disappearance. The commercial pesticide solutions containing imidacloprid and phosphamidon are also successfully degraded over these composites with the established conditions. The data indicates that 10 wt% TiO(2)/SBA-15 composite is an effective and highly active system for the pesticide degradations.

Non-destructive controlled single-particle light scattering measurement

NASA Astrophysics Data System (ADS)

Maconi, G.; Penttilä, A.; Kassamakov, I.; Gritsevich, M.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

2018-01-01

We present a set of light scattering data measured from a millimeter-sized extraterrestrial rock sample. The data were acquired by our novel scatterometer, which enables accurate multi-wavelength measurements of single-particle samples whose position and orientation are controlled by ultrasonic levitation. The measurements demonstrate a non-destructive approach to derive optical properties of small mineral samples. This enables research on valuable materials, such as those returned from space missions or rare meteorites.

Degradation of paracetamol by pure bacterial cultures and their microbial consortium.

PubMed

Zhang, Lili; Hu, Jun; Zhu, Runye; Zhou, Qingwei; Chen, Jianmeng

2013-04-01

Three bacterial strains utilizing paracetamol as the sole carbon, nitrogen, and energy source were isolated from a paracetamol-degrading aerobic aggregate, and assigned to species of the genera Stenotrophomonas and Pseudomonas. The Stenotrophomonas species have not included any known paracetamol degraders until now. In batch cultures, the organisms f1, f2, and fg-2 could perform complete degradation of paracetamol at concentrations of 400, 2,500, and 2,000 mg/L or below, respectively. A combination of three microbial strains resulted in significantly improved degradation and mineralization of paracetamol. The co-culture was able to use paracetamol up to concentrations of 4,000 mg/L, and mineralized 87.1 % of the added paracetamol at the initial of 2,000 mg/L. Two key metabolites of the biodegradation pathway of paracetamol, 4-aminophenol, and hydroquinone were detected. Paracetamol was degraded predominantly via 4-aminophenol to hydroquinone with subsequent ring fission, suggesting new pathways for paracetamol-degrading bacteria. The degradation of paracetamol could thus be performed by the single isolates, but is stimulated by a synergistic interaction of the three-member consortium, suggesting a possible complementary interaction among the various isolates. The exact roles of each of the strains in the consortium need to be further elucidated.

Degradation of trimethylbenzene isomers by an enrichment culture under N{sub 2}O-reducing conditions

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

Haener, A.; Hoehener, P.; Zeyer, J.

1997-03-01

In mineral oil-contaminated soils and aquifers, monoaromatic hydrocarbons are often a major concern because of high water solubility and toxicity. Under aerobic conditions, these compounds are rapidly mineralized. However, only limited data are available on the anaerobic degradation. This study reports on the growth of an enrichment culture on 1,3,5-trimethylbenzene (TMB) and 1,2,4-TMB under N2O-reducing conditions, and provides carbon mass and electron balances for the biodegradation of 1,3,5-TMB. 43 refs., 3 figs.

Land Use and River Degradation Impact of Sand and Gravel Mining

NASA Astrophysics Data System (ADS)

Syah, Putra Rizal Ichsan; Hartuti, Purnaweni

2018-02-01

Sand and gravel mining is aimed at providing materials for infrastructure development, as well as providing economical source to the miners. However, the impacts of sand and gravel mining could also cause disturbances to ecological balance, since it is closely related to land use change and river degradation, besides causing conflicts in the miners, the government, and the private relationship. Therefore the government regulation and proper supervision are needed to preserve the ecological balance and decreasing the negative impacts of this mining, and therefore guarantee sustainable development.

Effect of different mixing and placement methods on the quality of MTA apical plug in simulated apexification model.

PubMed

Ghasemi, Negin; Janani, Maryam; Razi, Tahmineh; Atharmoghaddam, Faezeh

2017-03-01

It is necessary apical plug material to exhibit proper adaptation with the root canal walls. Presence of voids at the interface between the root canal wall and this material result in micro leakage, which might have a relationship with post treatment disease. The aim of the present study was to evaluate the effect of different mixing (manual and ultrasonic) and placement (manual and manual in association with indirect ultrasonic) method of Mineral Trioxide Aggregate (MTA) on the void count and dimension in the apical plug in natural teeth with simulated open apices. Eighty human maxillary central incisors were selected. After simulation of the open apex model, the teeth were assigned to 4 groups based on the mixing and placement techniques of MTA: group 1, manual mixing and manual placement; group 2, manual mixing and manual placement in association with indirect ultrasonic; group 3, ultrasonic mixing and and manual placement; and group 4, ultrasonic mixing and manual placement in association with indirect ultrasonic. The prepared samples were placed within gypsum sockets in which the periodontal ligament was reconstructed with polyether impression material. In group 1, after mixing, the material was condensed with a hand plugger. In group 2, after mixing, the ultrasonic tip was contacted with the hand plugger for 2 seconds. In groups 3 and 4, mixing was carried out with the ultrasonic tip for 5 seconds and in groups 3 and 4, similar to groups 1 and 2, respectively, the materials were placed as apical plugs, measuring 3 mm in length. A wet cotton pellet was placed at canal orifices and dressed with Cavit. After one week, the cone beam computed tomography (CBCT) technique was used to count the number of voids between the material and root canal walls. The void dimensions were determined using the following scoring system: score 1, absence of voids; score 2, the void size less than half of the dimensions of the evaluated cross-section; score 3, the void size larger than half of the dimensions of the evaluated cross-section. Chi-squared and Fisher's exact tests were used for statistical analyses. Statistical significance was set at P <0.05. The maximum (13) and minimum (3) number of voids were detected in groups 2 and 3, respectively. There were no significant differences between groups 1 and 3 in the number of voids ( p >0.05). Evaluation of void dimensions showed no score 3 in any of the study groups and the dimensions of all the voids conformed to score 2. Under the limitations of the present study, use of ultrasonic mixing and manual placement techniques resulted in a decrease in the number of voids in the apical plug. Key words: Apical plug, MTA, ultrasonic, void.

Aerobic mineralization of vinyl chloride by a bacterium of the order Actinomycetales.

PubMed Central

Phelps, T J; Malachowsky, K; Schram, R M; White, D C

1991-01-01

A gram-positive branched bacterium isolated from a trichloroethylene-degrading consortium mineralized vinyl chloride in growing cultures and cell suspensions. Greater than 67% of the [1,2-14C]vinyl chloride was mineralized to carbon dioxide, with approximately 10% of the radioactivity appearing in cell biomass and another 10% appearing in 14C-aqueous-phase products. PMID:1905522

Sonophotocatalytic mineralization of Norflurazon in aqueous environment.

PubMed

Sathishkumar, Panneerselvam; Mangalaraja, Ramalinga Viswanathan; Rozas, Oscar; Vergara, Carola; Mansilla, Héctor D; Gracia-Pinilla, M A; Anandan, Sambandam

2016-03-01

Norflurazon (4-chloro-5-(methylamino)-2-[3-(trifluoromethyl)phenyl]pyridazin-3(2H)-one; C12H9ClF3N3O) is an excellent weed controlling agent being practiced in the agricultural lands. The excessive addition or the undissolved Norflurazon (maximum solubility 28 mg/L at 25 °C) enters into the aquatic environment and causes the adverse effects associated with its high concentration. To avoid the perilous effects, visible light assisted photocatalysis set-up coupled with the 42 kHz ultrasound producing bath type sonicator is used to completely mineralize the Norflurazon. TiO2, ZnO and gold loaded zinc oxide nanocatalysts were utilized to study the mineralization of Norflurazon. Au-ZnO shows the greater efficiency for the sonophotocatalytic removal of Norflurazon among the various nanocatalysts employed to study the mineralization. The order of Norflurazon mineralization was sonophotocatalysis > sonocatalysis > photocatalysis. The additive effect was achieved for the sonophotocatalytic degradation. The high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometric (LCMS) analyses were employed to identify the various intermediates produced during the mineralization. The identification of four pseudo molecular ions and various intermediates using the LCMS analysis evidently suggests the sonophotocatalytic degradation was preceded in various decay pathways. A suitable mechanism has been proposed for the sonophotocatalytic mineralization of Norflurazon. Copyright © 2015 Elsevier Ltd. All rights reserved.

Persulfate activation by subsurface minerals.

PubMed

Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2010-06-25

Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (<7) and high pH (>12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems. 2010. Published by Elsevier B.V.

Degradation pathways of aniline in aqueous solutions during electro-oxidation with BDD electrodes and UV/H2O2 treatment.

PubMed

Benito, Aleix; Penadés, Aida; Lliberia, Josep Lluis; Gonzalez-Olmos, Rafael

2017-01-01

In this work, it has been studied the mineralization of aniline, a toxic substance of low biodegradability typically found in many industrial wastewaters, through electro-oxidation using boron doped diamond (BDD) electrodes and photo-oxidation (UV photolysis and UV/H 2 O 2 treatments). It was observed that in electro-oxidation and UV/H 2 O 2 , it was feasible to reach aniline mineralizations higher than 85%. Two different degradation routes have been observed during the aniline oxidation in these two treatments. The first route was the mineralization pathway, in which aniline was oxidized to CO 2 , water and nitrate. The second route was the polyaniline pathway in which polyanilines of high molecular weight are formed. The intermediate compounds involved in both degradation routes are different depending on the treatment used. In the electro-oxidation, denitrification processes were also observed. From an economical point of view, electro-oxidation of aniline using BDD electrodes is more interesting than UV/H 2 O 2 due it has an 87% lower operational cost. So, electro-oxidation using BDD electrodes seems to be a more suitable technique for the mineralization of wastewater containing aniline than UV or H 2 O 2 based technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultrasonic simulation of MSBLS multipath fading for orbiter landing configuration

NASA Technical Reports Server (NTRS)

Hayre, H. S.

1978-01-01

The on-shuttle antenna pattern of the MSBLS receiver, and the azimuth and elevation beamwidths were simulated by their corresponding ultrasonic transducer beams. The scanning rate for the azimuth and elevation beams was 1.75 degrees/second. The results were adjusted for full-scale maximum sinusoidal scan rates of 691 and 377 deg/sec for AZ and EL respectively. The rain drops were simulated by air bubbles, with a similar size distribution, in water. The rain volume was created along a part of the propagation path, and not on the runway, because it was found difficult to avoid an accumulation of bubbles on the runway surface and surroundings simulated by the model surface. Multipath fading from the ground, and its possible degrading effect on the orbiter received beam shape and the associated landing guidance parameters is discussed.

Analysis of the tenderisation of jumbo squid (Dosidicus gigas) meat by ultrasonic treatment using response surface methodology.

PubMed

Hu, Yaqin; Yu, Hiaxia; Dong, Kaicheng; Yang, Shuibing; Ye, Xingqian; Chen, Shiguo

2014-10-01

Due to its unique structure, jumbo squid (Dosidicus gigas) meat is sensitive to heat treatment, which makes the traditional squid products taste tough and hard. This study aimed to tenderise jumbo squid meat through ultrasonic treatment. Response surface methodology (RSM) was used to predict the tenderising effect of various treatment conditions. According to the results of RSM, the optimal conditions appeared to be a power of 186.9 W, a frequency of 25.6 kHz, and a time of 30.8 min, and the predicted values of flexibility and firmness under these optimal conditions were 2.40 mm and 435.1 g, respectively. Protein degradation and a broken muscle fibre structure were observed through histological assay and SDS-PAGE, which suggests a satisfactory tenderisation effect. Copyright © 2014. Published by Elsevier Ltd.

High temperature ultrasonic transducers for the generation of guided waves for non-destructive evaluation of pipes

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

Sinding, K.; Searfass, C.; Malarich, N.

2014-02-18

Applications for non-destructive evaluation and structural health monitoring of steam generators require ultrasonic transducers capable of withstanding the high temperatures of the pipes and heat exchangers. These applications require a strong coupling of the transducer to the heat exchanger’s complex geometry at the elevated temperatures. Our objective is to use spray-on piezo-electrics for depositing comb transducers onto the curved surfaces. This paper shows results for composite transducers such as lead zirconate titanate/ bismuth titanate and bismuth titanate/ lithium niobate. The comb transducers were prepared by precision laser ablation. The feasibility of producing second harmonic waves in rods with these spay-onmore » comb transducers was demonstrated and paves the way toward measuring material degradation early-on before crack initiation occurs.« less

High-Performance Acousto-Ultrasonic Scan System Being Developed

NASA Technical Reports Server (NTRS)

Roth, Don J.; Martin, Richard E.; Cosgriff, Laura M.; Gyekenyesi, Andrew L.; Kautz, Harold E.

2003-01-01

Acousto-ultrasonic (AU) interrogation is a single-sided nondestructive evaluation (NDE) technique employing separated sending and receiving transducers. It is used for assessing the microstructural condition and distributed damage state of the material between the transducers. AU is complementary to more traditional NDE methods, such as ultrasonic cscan, x-ray radiography, and thermographic inspection, which tend to be used primarily for discrete flaw detection. Throughout its history, AU has been used to inspect polymer matrix composites, metal matrix composites, ceramic matrix composites, and even monolithic metallic materials. The development of a high-performance automated AU scan system for characterizing within-sample microstructural and property homogeneity is currently in a prototype stage at NASA. This year, essential AU technology was reviewed. In addition, the basic hardware and software configuration for the scanner was developed, and preliminary results with the system were described. Mechanical and environmental loads applied to composite materials can cause distributed damage (as well as discrete defects) that plays a significant role in the degradation of physical properties. Such damage includes fiber/matrix debonding (interface failure), matrix microcracking, and fiber fracture and buckling. Investigations at the NASA Glenn Research Center have shown that traditional NDE scan inspection methods such as ultrasonic c-scan, x-ray imaging, and thermographic imaging tend to be more suited to discrete defect detection rather than the characterization of accumulated distributed micro-damage in composites. Since AU is focused on assessing the distributed micro-damage state of the material in between the sending and receiving transducers, it has proven to be quite suitable for assessing the relative composite material state. One major success story at Glenn with AU measurements has been the correlation between the ultrasonic decay rate obtained during AU inspection and the mechanical modulus (stiffness) seen during fatigue experiments with silicon carbide/silicon carbide (SiC/SiC) ceramic matrix composite samples. As shown in the figure, ultrasonic decay increased as the modulus decreased for the ceramic matrix composite tensile fatigue samples. The likely microstructural reason for the decrease in modulus (and increase in ultrasonic decay) is the matrix microcracking that commonly occurs during fatigue testing of these materials. Ultrasonic decay has shown the capability to track the pattern of transverse cracking and fiber breakage in these composites.

High-Performance Acousto-Ultrasonic Scan System Being Developed

NASA Technical Reports Server (NTRS)

Roth, Don J.; Martin, Richard E.; Cosgriff, Laura M.; Gyekenyesi, Andrew L.; Kautz, Harold E.

2003-01-01

Acousto-ultrasonic (AU) interrogation is a single-sided nondestructive evaluation (NDE) technique employing separated sending and receiving transducers. It is used for assessing the microstructural condition and distributed damage state of the material between the transducers. AU is complementary to more traditional NDE methods, such as ultrasonic cscan, x-ray radiography, and thermographic inspection, which tend to be used primarily for discrete flaw detection. Throughout its history, AU has been used to inspect polymer matrix composites, metal matrix composites, ceramic matrix composites, and even monolithic metallic materials. The development of a high-performance automated AU scan system for characterizing within-sample microstructural and property homogeneity is currently in a prototype stage at NASA. This year, essential AU technology was reviewed. In addition, the basic hardware and software configuration for the scanner was developed, and preliminary results with the system were described. Mechanical and environmental loads applied to composite materials can cause distributed damage (as well as discrete defects) that plays a significant role in the degradation of physical properties. Such damage includes fiber/matrix debonding (interface failure), matrix microcracking, and fiber fracture and buckling. Investigations at the NASA Glenn Research Center have shown that traditional NDE scan inspection methods such as ultrasonic c-scan, x-ray imaging, and thermographic imaging tend to be more suited to discrete defect detection rather than the characterization of accumulated distributed microdamage in composites. Since AU is focused on assessing the distributed microdamage state of the material in between the sending and receiving transducers, it has proven to be quite suitable for assessing the relative composite material state. One major success story at Glenn with AU measurements has been the correlation between the ultrasonic decay rate obtained during AU inspection and the mechanical modulus (stiffness) seen during fatigue experiments with silicon carbide/silicon carbide (SiC/SiC) ceramic matrix composite samples. As shown in the figure, ultrasonic decay increased as the modulus decreased for the ceramic matrix composite tensile fatigue samples. The likely microstructural reason for the decrease in modulus (and increase in ultrasonic decay) is the matrix microcracking that commonly occurs during fatigue testing of these materials. Ultrasonic decay has shown the capability to track the pattern of transverse cracking and fiber breakage in these composites.

Ultrasound degradation of xanthan polymer in aqueous solution: Its scission mechanism and the effect of NaCl incorporation.

PubMed

Saleh, H M; Annuar, M S M; Simarani, K

2017-11-01

Degradation of xanthan polymer in aqueous solution by ultrasonic irradiation was investigated. The effects of selected variables i.e. sonication intensity, irradiation time, concentration of xanthan gum and molar concentration of NaCl in solution were studied. Combined approach of full factorial design and conventional one-factor-at-a-time was applied to obtain optimum degradation at sonication power intensity of 11.5Wcm -2 , irradiation time 120min and 0.1gL -1 xanthan in a salt-free solution. Molecular weight reduction of xanthan gum under sonication was described by an exponential decay function with higher rate constant for polymer degradation in the salt free solution. The limiting molecular weight where fragments no longer undergo scission was determined from the function. The incorporation of NaCl in xanthan solution resulted in a lower limiting molecular weight. The ultrasound-mediated degradation of aqueous xanthan polymer chain agreed with a random scission model. Side chain of xanthan polymer is proposed to be the primary site of scission action. Copyright © 2017 Elsevier B.V. All rights reserved.

Sonocatalytic removal of naproxen by synthesized zinc oxide nanoparticles on montmorillonite.

PubMed

Karaca, Melike; Kıranşan, Murat; Karaca, Semra; Khataee, Alireza; Karimi, Atefeh

2016-07-01

ZnO/MMT nanocomposite as sonocatalyst was prepared by immobilizing synthesized ZnO on the montmorillonite surface. The characteristics of as-prepared nanocomposite were studied by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) techniques. The synthesized samples were used as a catalyst for sonocatalytic degradation of naproxen. ZnO/MMT catalyst in the presence of ultrasound irradiation was more effective compared to pure ZnO nanoparticles and MMT particles in the sonocatalysis of naproxen. The effect of different operational parameters on the sonocatalytic degradation of naproxen including initial drug concentration, sonocatalyst dosage, solution pH, ultrasonic power and the presence of organic and inorganic scavengers were evaluated. It was found that the presence of the scavengers suppressed the sonocatalytic degradation efficiency. The reusability of the nanocomposite was examined in several consecutive runs, and the degradation efficiency decreased only 2% after 5 repeated runs. The main intermediates of naproxen degradation were determined by gas chromatography-mass spectrometry (GC-Mass). Copyright © 2016 Elsevier B.V. All rights reserved.

Sonocatalytic degradation of methylene blue by a novel graphene quantum dots anchored CdSe nanocatalyst.

PubMed

Sajjadi, Saeed; Khataee, Alireza; Kamali, Mehdi

2017-11-01

Cadmium selenide/graphene quantum dots (CdSe/GQDs) nanocatalyst with small band gap energy and a large specific surface area was produced via a facile three-step sonochemical-hydrothermal process. The features of the as-prepared CdSe, GQDs and CdSe/GQDs samples were characterized by photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), diffuse-reflectance spectrophotometer (DRS), and Brunauer-Emmett-Teller (BET) analysis. The sonocatalytic activity of the synthesized CdSe/GQDs was effectively accelerated compared with that of pure CdSe nanoparticles in degradation of methylene blue (MB). The influence of the CdSe/GQDs dosage (0.25-1.25g/L), initial MB concentration (20-30mg/L), initial solution pH (3-12), and ultrasonic output power (200-600W/L) were examined on the sonocatalytic treatment of MB aqueous solutions. The degradation efficiency (DE%) of 99% attained at 1g/L of CdSe/GQDs, 20mg/L of MB, pH of 9, and an output power of 200W/L at 90min of ultrasonic irradiation. Furthermore, DE% increased with addition of K 2 S 2 O 8 and H 2 O 2 as the enhancers via producing more free radicals. However, addition of sulfate, carbonate, and chloride as radical sweeper decreased DE%. Furthermore, well-reusability of the CdSe/GQDs sonocatalyst was demonstrated for 5 successive runs and some of the sonocatalytic generated intermediates were indicated by GC-MS analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Acousto-ultrasonics to Assess Material and Structural Properties

NASA Technical Reports Server (NTRS)

Kautz, Harold E.

2002-01-01

This report was created to serve as a manual for applying the Acousto-Ultrasonic NDE method, as practiced at NASA Glenn, to the study of materials and structures for a wide range of applications. Three state of the art acousto-ultrasonic (A-U) analysis parameters, ultrasonic decay (UD) rate, mean time (or skewing factor, "s"), and the centroid of the power spectrum, "f(sub c)," have been studied and applied at GRC for NDE interrogation of various materials and structures of aerospace interest. In addition to this, a unique application of Lamb wave analysis is shown. An appendix gives a brief overview of Lamb Wave analysis. This paper presents the analysis employed to calculate these parameters and the development and reasoning behind their use. It also discusses the planning of A-U measurements for materials and structures to be studied. Types of transducer coupling are discussed including contact and non-contact via laser and air. Experimental planning includes matching transducer frequency range to material and geometry of the specimen to be studied. The effect on results of initially zeroing the DC component of the ultrasonic waveform is compared with not doing so. A wide range of interrogation problems are addressed via the application of these analysis parameters to real specimens is shown for five cases: Case 1: Differences in density in [0] SiC/RBSN ceramic matrix composite. Case 2: Effect of tensile fatigue cycling in [+/-45] SiC/SiC ceramic matrix composite. Case 3: Detecting creep life, and failure, in Udimet 520 Nickel-Based Super Alloy. Case 4: Detecting Surface Layer Formation in T-650-35/PMR-15 Polymer Matrix Composites Panels due to Thermal Aging. Case 5: Detecting Spin Test Degradation in PMC Flywheels. Among these cases a wide range of materials and geometries are studied.

Enrichment and characterization of anaerobic TNT-degrading bacteria

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

Roberts, D.J.; Pendharkar, S.

1995-12-31

Three media constitutions were used to enrich for mixed cultures capable of degrading 2,4,6-trinitrotoluene (TNT) under strictly anaerobic conditions. The media were derived from a mineral salts solution buffered to pH 7 with CO{sub 2}/bicarbonate and all contained TNT. The cultures were enriched in the TNT mineral salts medium or the TNT mineral salts medium supplemented with glucose, yeast extract, or ammonia in various combinations. Inocula were obtained from a treated soil, previously contaminated with dinoseb and then treated using anaerobic procedures, or from a bench-top aqueous culture, maintained with an extract from a munitions-contaminated soil for more than 4more » years. Several cultures reduced TNT, producing 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene as the major products. The cultures were unable to effectively remove TNT when cross-transferred to the media they were not enriched on, suggesting that different media had enriched different subcultures form the original inoculum. The treated soil provided the most successful inoculum. Two media were chosen for further studies. Medium 1 contained TNT and glucose and produced a culture that might have used TNT as a nitrogen source. Medium 2, containing TNT and yeast extract, enriched cultures that degraded TNT, accumulating small amounts of p-cresol during the degradation.« less

Photocatalytic degradation of 5-nitro-1,2,4-triazol-3-one NTO in aqueous suspension of TiO2. Comparison with Fenton oxidation.

PubMed

Le Campion, L; Giannotti, C; Ouazzani, J

1999-03-01

5-nitro-1,2,4-triazol-3-one (NTO) is a powerful insensitive explosive, present in industrial waste waters. A remediation method based on photochemical decomposition and Fenton oxidation of NTO has been evaluated by monitoring the mineralization of 14C-labelled NTO. The TiO2-catalyzed photodegradation (lambda > 290 nm, TiO2 0.4 g/l, NTO 150 mg/l)) leads to the complete mineralization of NTO in 3 hours. This degradation involves a simultaneous denitrification and ring scission of NTO leading to nitrites, nitrates and carbon dioxide. No significant photo-degradation of NTO was detected in the absence of the catalyst. Long term irradiation over one week, leads to a complete degradation of concentrated NTO (5 g/l), suggesting that this method could be useful to clean-up NTO wastes. Fenton oxidation offers an efficient cost-effective method for NTO remediation. This reaction is faster that the TiO2 catalyzed photolysis and find application on the mineralization of high concentrations of NTO (15 g/l). Fenton oxidation provokes ring cleavage and subsequent elimination of the two carbon atoms of NTO as CO2. During this reaction, the nitro group is completely transformed into nitrates.

Dual element (CCl) isotope approach to distinguish abiotic reactions of chlorinated methanes by Fe(0) and by Fe(II) on iron minerals at neutral and alkaline pH.

PubMed

Rodríguez-Fernández, Diana; Heckel, Benjamin; Torrentó, Clara; Meyer, Armin; Elsner, Martin; Hunkeler, Daniel; Soler, Albert; Rosell, Mònica; Domènech, Cristina

2018-05-07

A dual element CCl isotopic study was performed for assessing chlorinated methanes (CMs) abiotic transformation reactions mediated by iron minerals and Fe(0) to further distinguish them in natural attenuation monitoring or when applying remediation strategies in polluted sites. Isotope fractionation was investigated during carbon tetrachloride (CT) and chloroform (CF) degradation in anoxic batch experiments with Fe(0), with FeCl 2 (aq), and with Fe-bearing minerals (magnetite, Mag and pyrite, Py) amended with FeCl 2 (aq), at two different pH values (7 and 12) representative of field and remediation conditions. At pH 7, only CT batches with Fe(0) and Py underwent degradation and CF accumulation evidenced hydrogenolysis. With Py, thiolytic reduction was revealed by CS 2 yield and is a likely reason for different Λ value (Δδ 13 C/Δδ 37 Cl) comparing with Fe(0) experiments at pH 7 (2.9 ± 0.5 and 6.1 ± 0.5, respectively). At pH 12, all CT experiments showed degradation to CF, again with significant differences in Λ values between Fe(0) (5.8 ± 0.4) and Fe-bearing minerals (Mag, 2 ± 1, and Py, 3.7 ± 0.9), probably evidencing other parallel pathways (hydrolytic and thiolytic reduction). Variation of pH did not significantly affect the Λ values of CT degradation by Fe(0) nor Py. CF degradation by Fe(0) at pH 12 showed a Λ (8 ± 1) similar to that reported at pH 7 (8 ± 2), suggesting CF hydrogenolysis as the main reaction and that CF alkaline hydrolysis (13.0 ± 0.8) was negligible. Our data establish a base for discerning the predominant or combined pathways of CMs natural attenuation or for assessing the effectiveness of remediation strategies using recycled minerals or Fe(0). Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of surfactants on fluoranthene mineralization by Sphingomonas paucimobilis strain EPA 505

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

Lantz, S.; Mueller, J.G.; Lin, J.E.

Past results from surfactant-enriched biodegradation studies have been equivocal because of inhibitory effects of the surfactants and a poor understanding of the characteristics of PAH-degrading microorganisms that make them responsive to surfactants. The authors have studied the mineralization of {sup 14}C-radiolabeled fluoranthene by high cell masses of Sphingomonas paucimobilis, strain EPA 505, and have shown that initial rates of mineralization can be enhanced by concentrations of the surfactant Triton X-100 as high as 2%. Mass balances are reported that show complete degradation of fluoranthene. The presence of soil stimulated biodegradation of fluoranthene in the same manner as surfactants, presumably becausemore » of increased dissolution rates from soil particulates. The usefulness of this bacterium in the bioremediation of PAH-contaminated soil is discussed.« less

Influence of ultrasound or halogen light on microleakage and hardness of enamel adjacent to glass ionomer cement.

PubMed

Guglielmi, Camila Almeida Brandão; Mohana, Anice; Hesse, Daniela; Lenzi, Tathiane Larissa; Bonini, Gabriela Cunha; Raggio, Daniela Prócida

2012-03-01

The use of external sources of energy may accelerate the setting rate of glass ionomer cements (GICs) allowing better initial mechanical properties. To investigate the influence of ultrasound and halogen light on the microleakage and hardness of enamel adjacent to GIC restorations, after artificial caries challenge. Cavities were prepared in 60 primary canines, restored with GIC, and randomly distributed into three groups: control group (CG), light group (LG) - irradiation with a halogen light-curing unit for 60s, and ultrasonic group (UG) - application of ultrasonic scaler device for 15s. All specimens were then submitted to a cariogenic challenge in a pH cycling model. Half of sample in each group were immersed in methylene blue for 4h and sectioned for dye penetration analysis. The remaining specimens were submitted to Knoop cross-sectional microhardness assessments, and mineral changes were calculated for adjacent enamel. Data were compared using Kruskal-Wallis test and two-way ANOVA with 5% significance. Higher dye penetration was observed for the UG (P<0.01). No significant mineral changes were observed between groups (P=0.844). The use of halogen light-curing unit does not seem to interfere with the properties of GICs, whereas the use of ultrasound can affect its marginal sealing. © 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.

Mechanical properties of concrete containing a high volume of tire-rubber particles.

PubMed

Khaloo, Ali R; Dehestani, M; Rahmatabadi, P

2008-12-01

Due to the increasingly serious environmental problems presented by waste tires, the feasibility of using elastic and flexible tire-rubber particles as aggregate in concrete is investigated in this study. Tire-rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete. These particles were used to replace 12.5%, 25%, 37.5%, and 50% of the total mineral aggregate's volume in concrete. Cylindrical shape concrete specimens 15 cm in diameter and 30 cm in height were fabricated and cured. The fresh rubberized concrete exhibited lower unit weight and acceptable workability compared to plain concrete. The results of a uniaxial compressive strain control test conducted on hardened concrete specimens indicate large reductions in the strength and tangential modulus of elasticity. A significant decrease in the brittle behavior of concrete with increasing rubber content is also demonstrated using nonlinearity indices. The maximum toughness index, indicating the post failure strength of concrete, occurs in concretes with 25% rubber content. Unlike plain concrete, the failure state in rubberized concrete occurs gently and uniformly, and does not cause any separation in the specimen. Crack width and its propagation velocity in rubberized concrete are lower than those of plain concrete. Ultrasonic analysis reveals large reductions in the ultrasonic modulus and high sound absorption for tire-rubber concrete.

Synthesis spherical porous hydroxyapatite/graphene oxide composites by ultrasonic-assisted method for biomedical applications.

PubMed

Duan, Peizhen; Shen, Juan; Zou, Guohong; Xia, Xu; Jin, Bo; Yu, Jiaxin

2018-04-10

Spherical porous hydroxyapatite (SHA)/graphene oxide (GO) composites with different GO (w/w) content of 16%, 40%, and 71% have been fabricated through a facile and controllable ultrasonic-assisted method at room temperature. The products were characterized by x-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, mechanical testing and biomimetic mineralization. Results showed SHA were covered by GO, and SHA/GO composites had an irregular surface with different degrees of wrinkles. The elastic modulus and hardness of SHA/GO-3 composites were up to 12.45 ± 0.33 GPa and 686.67 ± 26.95 MPa, which indicated that the contents of GO had an effect on SHA/GO composites. And the mechanical properties of SHA/GO-2 composites were similar to SHA particles. The biomimetic mineralization in SBF solution showed the bone-like apatite layer on composites surface, which demonstrated that the SHA/GO materials had osseointegration property. Moreover, in vitro cytocompatibility of SHA/GO-2 composites and pure GO were evaluated by cell adhesion and proliferation tests using MC3T3-E1 cells, which demonstrated that the SHA/GO composites can act as a good template for the cells growth and adhesion. These results suggested that the SHA/GO composites will be a promising material for biomedical application.

Sonophotocatalysis in advanced oxidation process: a short review.

PubMed

Joseph, Collin G; Li Puma, Gianluca; Bono, Awang; Krishnaiah, Duduku

2009-06-01

Sonophotocatalysis involves the use of a combination of ultrasonic sound waves, ultraviolet radiation and a semiconductor photocatalyst to enhance a chemical reaction by the formation of free radicals in aqueous systems. Researchers have used sonophotocatalysis in a variety of investigations i.e. from water decontamination to direct pollutant degradation. This degradation process provides an excellent opportunity to reduce reaction time and the amount of reagents used without the need for extreme physical conditions. Given its advantages, the sonophotocatalysis process has a futuristic application from an engineering and fundamental aspect in commercial applications. A detailed search of published reports was done and analyzed in this paper with respect to sonication, photocatalysis and advanced oxidation processes.

Organo-mineral complexation alters carbon and nitrogen cycling in stream microbial assemblages

NASA Astrophysics Data System (ADS)

Hunter, William Ross; Wanek, Wolfgang; Prommer, Judith; Mooshammer, Maria; Battin, Tom

2014-05-01

Inland waters are of global biogeochemical importance receiving carbon inputs of ~ 4.8 Pg C y-1. Of this 12 % is buried, 18 % transported to the oceans, and 70 % supports aquatic secondary production. However, the mechanisms that determine the fate of organic matter (OM) in these systems are poorly defined. One important aspect is the formation of organo-mineral complexes in aquatic systems and their potential as a route for OM transport and burial vs. microbial utilization as organic carbon (C) and nitrogen (N) sources. Organo-mineral particles form by sorption of dissolved OM to freshly eroded mineral surfaces and may contribute to ecosystem-scale particulate OM fluxes. We tested the availability of mineral-sorbed OM as a C & N source for streamwater microbial assemblages and streambed biofilms. Organo-mineral particles were constructed in vitro by sorption of 13C:15N-labelled amino acids to hydrated kaolin particles, and microbial degradation of these particles compared with equivalent doses of 13C:15N-labelled free amino acids. Experiments were conducted in 120 ml mesocosms over 7 days using biofilms and streamwater sampled from the Oberer Seebach stream (Austria), tracing assimilation and mineralization of 13C and 15N labels from mineral-sorbed and dissolved amino acids. Here we present data on the effects of organo-mineral sorption upon amino acid mineralization and its C:N stoichiometry. Organo-mineral sorption had a significant effect upon microbial activity, restricting C and N mineralization by both the biofilm and streamwater treatments. Distinct differences in community response were observed, with both dissolved and mineral-stabilized amino acids playing an enhanced role in the metabolism of the streamwater microbial community. Mineral-sorption of amino acids differentially affected C & N mineralization and reduced the C:N ratio of the dissolved amino acid pool. The present study demonstrates that organo-mineral complexes restrict microbial degradation of OM and may, consequently, alter the carbon and nitrogen cycling dynamics within aquatic ecosystems.

Efficient electrochemical degradation of multiwall carbon nanotubes.

PubMed

Reipa, Vytas; Hanna, Shannon K; Urbas, Aaron; Sander, Lane; Elliott, John; Conny, Joseph; Petersen, Elijah J

2018-07-15

As the production mass of multiwall carbon nanotubes (MWCNT) increases, the potential for human and environmental exposure to MWCNTs may also increase. We have shown that exposing an aqueous suspension of pristine MWCNTs to an intense oxidative treatment in an electrochemical reactor, equipped with an efficient hydroxyl radical generating Boron Doped Diamond (BDD) anode, leads to their almost complete mineralization. Thermal optical transmittance analysis showed a total carbon mass loss of over two orders of magnitude due to the electrochemical treatment, a result consistent with measurements of the degraded MWCNT suspensions using UV-vis absorbance. Liquid chromatography data excludes substantial accumulation of the low molecular weight reaction products. Therefore, up to 99% of the initially suspended MWCNT mass is completely mineralized into gaseous products such as CO 2 and volatile organic carbon. Scanning electron microscopy (SEM) images show sporadic opaque carbon clusters suggesting the remaining nanotubes are transformed into structure-less carbon during their electrochemical mineralization. Environmental toxicity of pristine and degraded MWCNTs was assessed using Caenorhabditis elegans nematodes and revealed a major reduction in the MWCNT toxicity after treatment in the electrochemical flow-by reactor. Published by Elsevier B.V.

Ultrasonic device for measuring periodontal attachment levels

NASA Astrophysics Data System (ADS)

Lynch, J. E.; Hinders, M. K.

2002-07-01

Periodontal disease is manifested clinically by a degradation of the ligament that attaches the tooth to the bone. The most widely used diagnostic tool for assessment of periodontal diseases, measurement of periodontal attachment loss with a manual probe, may overestimate attachment loss by as much as 2 mm in untreated sites, while underestimating attachment loss by an even greater margin following treatment. Manual probing is also invasive, which causes patient discomfort. This work describes the development and testing of an ultrasonographic periodontal probe designed to replace manual probing. It uses a thin stream of water to project an ultrasonic beam into the periodontal pocket, and then measures echoes off features within the pocket. To do so, the ultrasonic beam must be narrowed from 2 (the diameter of the transducer) to 0.5 mm (the approximate width of the periodontal pocket at the gingival margin). The proper choice of transducer frequency, the proper method for controlling water flow from the probe, and a model for interpreting these echoes are also addressed. Initial results indicate that the device measures echoes from the hard tissue of the tooth surface, and that the periodontal attachment level can be inferred from these echoes.

Structural health monitoring ultrasonic thickness measurement accuracy and reliability of various time-of-flight calculation methods

NASA Astrophysics Data System (ADS)

Eason, Thomas J.; Bond, Leonard J.; Lozev, Mark G.

2016-02-01

The accuracy, precision, and reliability of ultrasonic thickness structural health monitoring systems are discussed in-cluding the influence of systematic and environmental factors. To quantify some of these factors, a compression wave ultrasonic thickness structural health monitoring experiment is conducted on a flat calibration block at ambient temperature with forty four thin-film sol-gel transducers and various time-of-flight thickness calculation methods. As an initial calibration, the voltage response signals from each sensor are used to determine the common material velocity as well as the signal offset unique to each calculation method. Next, the measurement precision of the thickness error of each method is determined with a proposed weighted censored relative maximum likelihood analysis technique incorporating the propagation of asymmetric measurement uncertainty. The results are presented as upper and lower confidence limits analogous to the a90/95 terminology used in industry recognized Probability-of-Detection assessments. Future work is proposed to apply the statistical analysis technique to quantify measurement precision of various thickness calculation methods under different environmental conditions such as high temperature, rough back-wall surface, and system degradation with an intended application to monitor naphthenic acid corrosion in oil refineries.

Synthesis of phosphonic acid silver-graphene oxide nanomaterials with photocatalytic activity through ultrasonic-assisted method.

PubMed

Li, Yongshen; Song, Yunna; Ma, Zheng; Niu, Shuai; Li, Jihui; Li, Ning

2018-06-01

In this article, phosphonic acid silver-graphene oxide nanomaterials (Nano-PAS-GO) was synthesized from silver nitrate (AgNO 3 ) solution and phosphoric graphene oxide (PGO) via the convenient ultrasonic-assisted method, and the structure and morphology were characterized, and the photocatalytic activity and recyclability were evaluated through photocatalyzing degradation of Rhodamin B (RhB) aqueous solution, and the possible photocatalytic mechanism was also discussed. Based on those, it was confirmed that Nano-PAS-GO has been synthesized from AgNO 3 solution and PGO colloidal suspension under ultrasonic-assisted condition, and Nano-PAS-GO has consisted of phosphoric acid silver nanoparticles and GO with 2D lattice (2D GO lattice) connected in the form of C-P bonds, and the photodegradation rate of Nano-PAS-GO for RhB aqueous solution has reached 93.99%, and Nano-PAS-GO has possessed the nicer recyclability when the photocatalytic time was 50 min. From those results, the strong and stable interface . between PAS nanoparticles and 2D GO lattice connected in the form of the covalent bonds has effectively inhibited the occurrence of the photocorrosion phenomenon. Copyright © 2018 Elsevier B.V. All rights reserved.

Ultrasonic Wall Thickness Monitoring at High Temperatures (>500 °C)

NASA Astrophysics Data System (ADS)

Cegla, F. B.; Allin, J.; Davies, J. O.; Collins, P.; Cawley, P.

2011-06-01

Corrosion and erosion shorten the life of components that are used in the petrochemical industry. In order to mitigate the safety and financial risks posed by the degradation mechanisms, plant operators monitor wall thicknesses at regular inspection intervals. In high temperature locations inspections have to be carried out at plant shut downs because conventional ultrasonic sensors cannot withstand the high operating temperatures. The authors have developed a waveguide based high temperature thickness gauge for monitoring of wall thicknesses in high temperature areas. The waveguide allows the use of conventional transduction systems (max temp. 60 °C) at one end and guides ultrasonic waves into the high temperature region where the inspection is to be carried out. Slender stainless steel waveguides allow a temperature drop of ˜500-600 °C per 200 mm length to be sustained simply by natural convection cooling. This paper describes the technical challenges that had to be overcome (dispersion and source/receiver characteristics) in order to implement this "acoustic cable". A range of experimental results of thickness measurements on components of different thickness, and furnace tests at different temperatures are presented. An accelerated corrosion test that demonstrates the effectiveness of the monitoring for corrosion is also presented.

Sand/cement ratio evaluation on mortar using neural networks and ultrasonic transmission inspection.

PubMed

Molero, M; Segura, I; Izquierdo, M A G; Fuente, J V; Anaya, J J

2009-02-01

The quality and degradation state of building materials can be determined by nondestructive testing (NDT). These materials are composed of a cementitious matrix and particles or fragments of aggregates. Sand/cement ratio (s/c) provides the final material quality; however, the sand content can mask the matrix properties in a nondestructive measurement. Therefore, s/c ratio estimation is needed in nondestructive characterization of cementitious materials. In this study, a methodology to classify the sand content in mortar is presented. The methodology is based on ultrasonic transmission inspection, data reduction, and features extraction by principal components analysis (PCA), and neural network classification. This evaluation is carried out with several mortar samples, which were made while taking into account different cement types and s/c ratios. The estimated s/c ratio is determined by ultrasonic spectral attenuation with three different broadband transducers (0.5, 1, and 2 MHz). Statistical PCA to reduce the dimension of the captured traces has been applied. Feed-forward neural networks (NNs) are trained using principal components (PCs) and their outputs are used to display the estimated s/c ratios in false color images, showing the s/c ratio distribution of the mortar samples.

Photonic efficiency of the photodegradation of paracetamol in water by the photo-Fenton process.

PubMed

Yamal-Turbay, E; Ortega, E; Conte, L O; Graells, M; Mansilla, H D; Alfano, O M; Pérez-Moya, M

2015-01-01

An experimental study of the homogeneous Fenton and photo-Fenton degradation of 4-amidophenol (paracetamol, PCT) is presented. For all the operation conditions evaluated, PCT degradation is efficiently attained by both Fenton and photo-Fenton processes. Also, photonic efficiencies of PCT degradation and mineralization are determined under different experimental conditions, characterizing the influence of hydrogen peroxide (H2O2) and Fe(II) on both contaminant degradation and sample mineralization. The maximum photonic degradation efficiencies for 5 and 10 mg L(-1) Fe(II) were 3.9 (H2O2 = 189 mg L(-1)) and 5 (H2O2 = 378 mg L(-1)), respectively. For higher concentrations of oxidant, H2O2 acts as a "scavenger" radical, competing in pollutant degradation and reducing the reaction rate. Moreover, in order to quantify the consumption of the oxidizing agent, the specific consumption of the hydrogen peroxide was also evaluated. For all operating conditions of both hydrogen peroxide and Fe(II) concentration, the consumption values obtained for Fenton process were always higher than the corresponding values observed for photo-Fenton. This implies a less efficient use of the oxidizing agent for dark conditions.

Gneisses of Brazil's cultural heritage buildings and its most frequent degradations

NASA Astrophysics Data System (ADS)

Gilberto Costa, Antônio

2017-04-01

Macroscopic descriptions of cultural heritage buildings constructed using gneisses in the cities of Rio de Janeiro, Belo Horizonte and Ouro Preto, Brazil, allowed to identify alterations and degradations, in part conditioned by the mineralogical composition and the structures present in these stone materials. It is important to emphasize that: - some changes still begin in the environments where these materials were formed, experiencing an intensification from the processes of extraction, processing and application; - modifications occurring after the applications are understood herein as degradations. The studied gneisses present banding consisting of parts with different thicknesses and mineralogical contents. Due to these differentiated contents, clear bands were identified and constituted essentially by felsic minerals, such as feldspars and quartz, as well as dark bands formed by mafic minerals represented by: biotite, garnets, amphiboles, such as hornblende or pyroxene (hyperstene). In addition to these minerals, low contents of oxides and sulphides were found. Also under the influence of this distribution of minerals, planar structures or foliations, more or less developed, that can be very penetrative have been identified, mainly when these rocks were submitted to the performance of milonitization processes. From the set of changes and degradations observed stand out those related to the decomposition of minerals that make up these materials. In these cases, feldspars and other silicates, such as micas, amphiboles and pyroxenes, were decomposed due to the hydrolysis and products were generated which compromised the resistance of these stone materials, leading to their consequent disintegration. On the other hand, the presence of expansive clays in these products, caused volume increases which also contributed to the expansion of the weathered surface layer (blistering). This process may result detachments in the form of scales to cavities in cases of significant loss of components. Still related to minerals of these rocks, degradations occurred due to the oxidation of the iron present in these rocks in the silicates and oxides. This process, which was more intense in hot, tropical regions, was responsible for chromatic alterations with predominance of reddish color. When the action of this process occurs in conjunction with hydration, it becomes much more effective and manifests itself in much more extensive areas. In these cases, minerals containing iron, for example, have changed to hematite or limonite, causing important chromatic variations identified by the appearance of a yellow-brown coloration in the studied materials. In relation to the structural arrangements, the influence of these in the degradation processes was verified. Here we highlight the exfoliations and detachments parallel to the structures of these materials. Other detachments observed result from the formation of black crusts that end up leading to the appearance of bubbles or spells that eventually evolve into the detachments. Contrary to what is observed for others rocks with feldspar quartz composition, but with hypidiomorphic granular texture, rounding is not frequent.

Dentin-cement Interfacial Interaction

PubMed Central

Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

2012-01-01

The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

Genetic labelling and application of the isoproturon-mineralizing Sphingomonas sp. strain SRS2 in soil and rhizosphere.

PubMed

Kristensen, K E; Jacobsen, C S; Hansen, L H; Aamand, J; Morgan, J A W; Sternberg, C; Sørensen, S R

2006-09-01

To construct a luxAB-labelled Sphingomonas sp. strain SRS2 maintaining the ability to mineralize the herbicide isoproturon and usable for monitoring the survival and distribution of strain SRS2 on plant roots in laboratory systems. We inserted the mini-Tn5-luxAB marker into strain SRS2 using conjugational mating. In the transconjugant mutants luciferase was produced in varying levels. The mutants showed significant differences in their ability to degrade isoproturon. One luxAB-labelled mutant maintained the ability to mineralize isoproturon and was therefore selected for monitoring colonization of barley roots. We successfully constructed a genetically labelled isoproturon-mineralizing-strain SRS2 and demonstrated its ability to survive in soil and its colonization of rhizosphere. The construction of a luxAB-labelled strain SRS2 maintaining the degradative ability, provides a powerful tool for ecological studies serving as the basis for evaluating SRS2 as a bioremediation agent.

Laboratory degradation studies of 14C-atrazine and -isoproturon in soil from sugarcane cultivated fields under Kenyan tropical conditions.

PubMed

Getenga, Z M; Dörfler, U; Schroll, R

2009-06-01

A study to compare the degradation rates of atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diammine) and isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] in soils from sugarcane fields with different practices of herbicides application was carried out. (14)C-atrazine was poorly mineralized to (14)CO(2) (1.10% +/- 0.22%) after 139 days of incubation in soil without previous exposure to atrazine. In the same soil also with no previous isoproturon exposure isoproturon was mineralized to (14)CO(2) by 7.70% +/- 0.94%. Atrazine mineralization after 98 days was 13.4% +/- 0.30% in soil which discontinued the use of atrazine in 1997 while it was 89.9% +/- 1.23% in soil in which atrazine is currently being used. The isoproturon mineralization values were 7.24% +/- 0.85% and 22.97% +/- 0.96% in soil which discontinued atrazine and soil currently using atrazine, respectively.

SERDP ER-1376 Enhancement of In Situ Bioremediation of Energetic Compounds by Coupled Abiotic/Biotic Processes:Final Report for 2004 - 2006

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

Szecsody, James E.; Comfort, Steve; Fredrickson, Herbert L.

2007-08-07

This project was initiated by SERDP to quantify processes and determine the effectiveness of abiotic/biotic mineralization of energetics (RDX, HMX, TNT) in aquifer sediments by combinations of biostimulation (carbon, trace nutrient additions) and chemical reduction of sediment to create a reducing environment. Initially it was hypothesized that a balance of chemical reduction of sediment and biostimulation would increase the RDX, HMX, and TNT mineralization rate significantly (by a combination of abiotic and biotic processes) so that this abiotic/biotic treatment may be a more efficient for remediation than biotic treatment alone in some cases. Because both abiotic and biotic processes aremore » involved in energetic mineralization in sediments, it was further hypothesized that consideration for both abiotic reduction and microbial growth was need to optimize the sediment system for the most rapid mineralization rate. Results show that there are separate optimal abiotic/biostimulation aquifer sediment treatments for RDX/HMX and for TNT. Optimal sediment treatment for RDX and HMX (which have chemical similarities and similar degradation pathways) is mainly chemical reduction of sediment, which increased the RDX/HMX mineralization rate 100 to150 times (relative to untreated sediment), with additional carbon or trace nutrient addition, which increased the RDX/HMX mineralization rate an additional 3 to 4 times. In contrast, the optimal aquifer sediment treatment for TNT involves mainly biostimulation (glucose addition), which stimulates a TNT/glucose cometabolic degradation pathway (6.8 times more rapid than untreated sediment), degrading TNT to amino-intermediates that irreversibly sorb (i.e., end product is not CO2). The TNT mass migration risk is minimized by these transformation reactions, as the triaminotoluene and 2,4- and 2,6-diaminonitrotoluene products that irreversibly sorb are no longer mobile in the subsurface environment. These transformation rates are increased 13 times further by chemical reduction of sediment. Dithionite reduction alone is not an effective treatment for TNT (intermediates that irreversibly sorb are not produced), even though the TNT degradation rate (to 2- or 4-aminodinitrotoluene) increases.« less

High-frequency guided ultrasonic waves to monitor corrosion thickness loss

NASA Astrophysics Data System (ADS)

Fromme, Paul; Bernhard, Fabian; Masserey, Bernard

2017-02-01

Corrosion due to adverse environmental conditions can occur for a range of industrial structures, e.g., ships and offshore oil platforms. Pitting corrosion and generalized corrosion can lead to the reduction of the strength and thus degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided ultrasonic waves propagating along the structure. Using standard ultrasonic transducers with single sided access to the structure, the two fundamental Lamb wave modes were selectively generated simultaneously, penetrating through the complete thickness of the structure. The wave propagation and interference of the guided wave modes depends on the thickness of the structure. Numerical simulations were performed using a 2D Finite Difference Method (FDM) algorithm in order to visualize the guided wave propagation and energy transfer across the plate thickness. Laboratory experiments were conducted and the wall thickness reduced initially uniformly by milling of the steel structure. Further measurements were conducted using accelerated corrosion in salt water. From the measured signal change due to the wave mode interference, the wall thickness reduction was monitored and good agreement with theoretical predictions was achieved. Corrosion can lead to non-uniform thickness reduction and the influence of this on the propagation of the high frequency guided ultrasonic waves was investigated. The wave propagation in a steel specimen with varying thickness was measured experimentally and the influence on the wave propagation characteristics quantified.

Rapid degradation, mineralization and detoxification of pharmaceutically active compounds in aqueous solution during pulsed corona discharge treatment.

PubMed

Singh, Raj Kamal; Philip, Ligy; Ramanujam, Sarathi

2017-09-15

In the present study, plasma generated by pulsed corona discharge was used for the degradation of diclofenac, carbamazepine and ciprofloxacin. Pollutants in aqueous solution were plasma treated under two categories: single and mixed pollutant condition. Mixed pollutant condition showed an antagonistic behaviour and thus the degradation time was higher for mixed condition compared to the single condition. At different voltage and frequencies, degradation efficiency followed the trend, diclofenac>carbamazepine>ciprofloxacin. Acidic pH slightly favoured the degradation process whereas in presence of radical scavengers (HCO 3 - , CO 3 2- and humic acid) the degradation yield was significantly decreased. With an input power of 101.5 W, complete degradation was achieved within 4-16 min of plasma treatment for pharmaceutical's concentrations of 1-10 mg/L. As the pollutant concentration increased from 1 to 10 mg/L, the pseudo first order rate constant decreased, while yield increased. Complete degradation pathway of diclofenac, carbamazepine and ciprofloxacin in plasma treatment process are proposed by identifying the intermediates using LC-MS analysis. TOC analysis confirmed 80% mineralization within 10 min of plasma treatment for higher pharmaceutical's concentrations of 10 mg/L. The microalgae ecotoxicity study and disc diffusion test confirmed the complete detoxification of PACs that took place after 6 min of plasma treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Field solar degradation of pesticides and emerging water contaminants mediated by polymer films containing titanium and iron oxide with synergistic heterogeneous photocatalytic activity at neutral pH.

PubMed

Mazille, F; Schoettl, T; Klamerth, N; Malato, S; Pulgarin, C

2010-05-01

Photocatalytic degradation of phenol, nalidixic acid, mixture of pesticides, and another of emerging contaminants in water was mediated by TiO(2) and iron oxide immobilized on functionalized polyvinyl fluoride films (PVF(f)-TiO(2)-Fe oxide) in a compound parabolic collector (CPC) solar photoreactor. During degradation, little iron leaching (<0.2mgL(-1)) was observed. Phenol was efficiently degraded and mineralized at operational pH<5 and nalidixic acid degradation was complete even at pH 7, but mineralization stopped at 35%. Pesticide mixture was slowly degraded (50%) after 150min of irradiation. Degradation of the emergent contaminant mixture was successful for eight compounds and less efficient for six other compounds. The significant reactivity differences between tested compounds were assigned to the differences in structure namely that the presence of complexing or chelating groups enhanced the rates. PVF(f)-TiO(2)-Fe oxide photoactivity gradually increased during 20 days of experiments. X-ray photoelectron spectroscopy (XPS) measurements revealed significant changes on the catalyst surface. These analyses confirm that during photocatalysis mediated by PVF(f)-TiO(2)-Fe oxide, some iron leaching led to enlargement of the TiO(2) surface exposed to light, increasing its synergy with iron oxides and leading to enhanced pollutant degradation.

Lignocellulose degradation during solid-state fermentation: Pleurotus ostreatus versus Phanerochaete chrysosporium

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

Kerem, Z.; Friesem, D.; Hadar, Y.

Lignocellulose degradation and activities related to lignin degradation were studied in the solid-state fermentation of cotton stalks by comparison two white rot fungi, Pleurotus ostreatus and Phanerochaete chrysosporium. P. chrysosporium grew vigorously, resulting in rapid, nonselective degradation of 55% of the organic components of the cotton stalks within 15 days. In contrast, P. ostreatus grew more slowly with obvious selectivity for lignin degradation and resulting in the degradation of only 20% of the organic matter after 30 days of incubation. The kinetics of {sup 14}C-lignin mineralization exhibited similar differences. In cultures of P. chrysosporium, mineralization ceased after 18 days, resultingmore » in the release of 12% of the total radioactivity as {sup 14}CO{sub 2}. In P. ostreatus, on the other hand, 17% of the total radioactivity was released in a steady rate throughout a period of 60 days of incubation. Laccase activity was only detected in water extracts of the P. ostreatus fermentation. No lignin peroxidase activity was detected in either the water extract or liquid cultures of this fungus. 2-Keto-4-thiomethyl butyric acid cleavage to ethylene correlated to lignin degradation in both fungi. A study of fungal activity under solid-state conditions, in contrast to those done under defined liquid culture, may help to better understand the mechanism involved in lignocellulose degradation.« less

An AgI@g-C3N4 hybrid core@shell structure: Stable and enhanced photocatalytic degradation

NASA Astrophysics Data System (ADS)

Liu, Li; Qi, Yuehong; Yang, Jinyi; Cui, Wenquan; Li, Xingang; Zhang, Zisheng

2015-12-01

A novel visible-light-active material AgI@g-C3N4 was prepared by ultrasonication/chemisorption method. The core@shell structure AgI@g-C3N4 catalyst showed high efficiency for the degradation of MB under visible light irradiation (λ > 420 nm). Nearly 96.5% of MB was degraded after 120 min of irradiation in the presence of the AgI@g-C3N4 photocatalyst. Superior stability was also observed in the cyclic runs indicating that the as prepared hybrid composite is highly desirable for the remediation of organic contaminated wastewaters. The improved photocatalytic performance is due to synergistic effects at the interface of AgI and g-C3N4 which can effectively accelerate the charge separation and reinforce the photostability of hybrid composite. The possible mechanism for the photocatalytic activity of AgI@g-C3N4 was tentatively proposed.

Durability of Cement Composites Reinforced with Sisal Fiber

NASA Astrophysics Data System (ADS)

Wei, Jianqiang

This dissertation focuses mainly on investigating the aging mechanisms and degradation kinetics of sisal fiber, as well as the approaches to mitigate its degradation in the matrix of cement composites. In contrast to previous works reported in the literature, a novel approach is proposed in this study to directly determine the fiber's degradation rate by separately studying the composition changes, mechanical and physical properties of the embedded sisal fibers. Cement hydration is presented to be a crucial factor in understanding fiber degradation behavior. The degradation mechanisms of natural fiber consist of mineralization of cell walls, alkali hydrolysis of lignin and hemicellulose, as well as the cellulose decomposition which includes stripping of cellulose microfibrils and alkaline hydrolysis of amorphous regions in cellulose chains. Two mineralization mechanisms, CH-mineralization and self-mineralization, are proposed. The degradation kinetics of sisal fiber in the cement matrix are also analyzed and a model to predict the degradation rate of cellulose for natural fiber embedded in cement is outlined. The results indicate that the time needed to completely degrade the cellulose in the matrix with cement replacement by 30wt.% metakaolin is 13 times longer than that in pure cement. A novel and scientific method is presented to determine accelerated aging conditions, and to evaluating sisal fiber's degradation rate and durability of natural fiber-reinforced cement composites. Among the static aggressive environments, the most effective approach for accelerating the degradation of natural fiber in cement composites is to soak the samples or change the humidity at 70 °C and higher temperature. However, the dynamic wetting and drying cycling treatment has a more accelerating effect on the alkali hydrolysis of fiber's amorphous components evidenced by the highest crystallinity indices, minimum content of holocellulose, and lowest tensile strength. Based on the understanding of degradation mechanisms, two approaches are proposed to mitigate the degradation of sisal fiber in the cement matrix. In order to relieve the aggressive environment of hydrated cement, cement substitution by a combination of metakaolin and nanoclay, and a combination of rice husk ash and limestone are studied. Both metakaolin and nanoclay significantly optimize the cement hydration, while the combination of these two supplementary cementitious materials validates their complementary and synergistic effect at different stages of aging. The presented approaches effectively reduce the calcium hydroxide content and the alkalinity of the pore solution, thereby mitigating the fiber degradation and improving both the initial mechanical properties and durability of the fiber-cement composites. The role of rice husk ash in cement modification is mainly as the active cementitious supplementary material. In order to improve the degradation resistance of sisal fiber itself, two novel, simple, and economical pretreatments of the fibers (thermal and sodium carbonate treatment) are investigated. Both thermal treatment and Na 2CO3 treatment effectively improve the durability of sisal fiber-reinforced concrete. The thermal treatment achieves improvement of cellulose's crystallization, which ensures the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali pore solution, is formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface.

Separation Process of Fine Coals by Ultrasonic Vibration Gas-Solid Fluidized Bed

PubMed Central

Wei, Hua; Xie, Weining

2017-01-01

Ultrasonic vibration gas-solid fluidized bed was proposed and introduced to separate fine coals (0.5–0.125 mm fraction). Several technological methods such as XRF, XRD, XPS, and EPMA were used to study the composition of heavy products to evaluate the separation effect. Results show that the ultrasonic vibration force field strengthens the particle separation process based on density when the vibration frequency is 35 kHz and the fluidization number is 1.8. The ash difference between the light and heavy products and the recovery of combustible material obtain the maximum values of 47.30% and 89.59%, respectively. The sulfur content of the heavy product reaches the maximum value of 6.78%. Chemical state analysis of sulfur shows that organic sulfur (-C-S-), sulfate-sulfur (-SO4), and pyrite-sulfur (-S2) are confirmed in the original coal and heavy product. Organic sulfur (-C-S-) is mainly concentrated in the light product, and pyrite-sulfur (-S2) is significantly enriched in the heavy product. The element composition, phase composition, backscatter imagery, and surface distribution of elements for heavy product show concentration of high-density minerals including pyrite, quartz, and kaolinite. Some harmful elements such as F, Pb, and As are also concentrated in the heavy product. PMID:28845160

[Piezosurgery for surgically assisted rapid maxillary expansion under local anesthesia].

PubMed

Sun, Hao; Li, Biao; Sun, Hao; Liu, Zhixu; Wang, Xudong

2014-08-01

This study evaluates piezosurgery for surgically assisted rapid maxillary expansion (SARME) under local anesthesia. SARME was performed on adults with maxillary transverse deficiency under local anesthesia with a piezosurgical device. Fourteen patients (six males and eight females) underwent lateral maxillary osteotomies, midpalatal osteotomies, and bilateral pterygomaxillary disjunction. The feelings of patients during the operation were determined through questionnaires. All patients underwent SARME in the out-patient operating room. The surgical procedures were completed under local anesthesia. All patients exhibited satisfactory tolerance. Ultrasonic bone-cutting surgery was recently introduced as a feasible alternative to the conventional tools of cranio-maxillofacial surgery for its technical characteristics of precision and safety. The device used was unique in that cutting action occurred when the tool was employed on mineralized tissues, but stoped on soft tissues. The results of the questionnaires showed that eight (57.14%) patients felt a mild sensation of ultrasonic vibration, tweleve (85.7 1%) felt mild tolerable pain and tooth soreness during surgery, and eleven (78.57%) felt little fear and hardly heard the ultrasonic sound. Preoperative and postoperative six months later measurements showed an evident effect of expansion. Piezosurgery enabled patients to undergo all the steps of SARME under local anesthesia, but more cases and longer follow-up are needed to verif ' the results.

Perfluorinated Surfactant Chain-Length Effects on Sonochemical Kinetics

NASA Astrophysics Data System (ADS)

Campbell, Tammy Y.; Vecitis, Chad D.; Mader, Brian T.; Hoffmann, Michael R.

2009-08-01

The sonochemical degradation kinetics of the aqueous perfluorochemicals (PFCs) perfluorobutanoate (PFBA), perfluorobutanesulfonate (PFBS), perfluorohexanoate (PFHA), and perfluorohexanesulfonate (PFHS) have been investigated. Surface tension measurements were used to evaluate chain-length effects on equilibrium air-water interface partitioning. The PFC air-water interface partitioning coefficients, KeqPF, and maximum surface concentrations, ΓmaxPF, were determined from the surface pressure equation of state for PFBA, PFBS, PFHA, and PFHS. Relative KeqPF values were dependent upon chain length KeqPFHS ≅ 2.1KeqPFHA ≅ 3.9KeqPFBS ≅ 5.0KeqPFBA, whereas relative ΓmaxPF values had minimal chain length dependence ΓmaxPFHS ≅ ΓmaxPFHA ≅ ΓmaxPFBS ≅ 2.2ΓmaxPFBA. The rates of sonolytic degradation were determined over a range of frequencies from 202 to 1060 kHz at dilute (<1 μM) initial PFC concentrations and are compared to previously reported results for their C8 analogs: perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). Under all conditions, the time-dependent PFC sonolytic degradation was observed to follow pseudo-first-order kinetics, i.e., below kinetic saturation, suggesting bubble-water interface populations were significantly below the adsorption maximum. The PFHX (where X = A or S) sonolysis rate constant was observed to peak at an ultrasonic frequency of 358 kHz, similar to that for PFOX. In contrast, the PFBX degradation rate constants had an apparent maximum at 610 kHz. Degradation rates observed for PFHX are similar to previously determined PFOX rates, kapp,358PFOX ≅ kapp,358PFHX. PFOX is sonolytically pyrolyzed at the transiently cavitating bubble-water interface, suggesting that rates should be proportional to equilibrium interfacial partitioning. However, relative equilibrium air-water interfacial partitioning predicts that KeqPFOX ≅ 5KeqPFHX. This suggests that at dilute PFC concentrations, adsorption to the bubble-water interface is ultrasonically enhanced due to high-velocity radial bubble oscillations. PFC sonochemical kinetics are slower for PFBS and further diminished for PFBA as compared to longer analogs, suggesting that PFBX surface films are of lower stability due to their greater water solubility.

Investigation of In-situ Biogeochemical Reduction of Chlorinated Solvents in Groundwater by Reduced Iron Minerals

EPA Science Inventory

Biogeochemical transformation is a process in which chlorinated solvents are degraded abiotically by reactive minerals formed by, at least in part or indirectly from, anaerobic biological processes. Five mulch biowall and/or vegetable oil-based bioremediation applications for tr...

Rock-degrading endophytic bacteria in cacti

Treesearch

M. Esther Puente; Ching Y. Li; Yoav Bashan

2009-01-01

A plant-bacterium association of the cardon cactus (Pachycereus pringlei) and endophytic bacteria promotes establishment of seedlings and growth on igneous rocks without soil. These bacteria weather several rock types and minerals, unbind significant amounts of useful minerals for plants from the rocks, fix in vitro N2. produce...

DEGRADATION OF MTBE INTERMEDIATES USING FENTON'S REAGENT

EPA Science Inventory

In a previous study, the chemical oxidation of MTBE at low concentrations in water using the Fenton's reagent (FR) was investigated. At certain reaction conditions the process achieved 99.99% degradation of MTBE but it did not result in complete MTBE mineralization. In the pres...

Degradation and Mineralization of Phenol Compounds with Goethite Catalyst and Mineralization Prediction Using Artificial Intelligence

PubMed Central

Tisa, Farhana; Davoody, Meysam; Abdul Raman, Abdul Aziz; Daud, Wan Mohd Ashri Wan

2015-01-01

The efficiency of phenol degradation via Fenton reaction using mixture of heterogeneous goethite catalyst with homogeneous ferrous ion was analyzed as a function of three independent variables, initial concentration of phenol (60 to 100 mg /L), weight ratio of initial concentration of phenol to that of H2O2 (1: 6 to 1: 14) and, weight ratio of initial concentration of goethite catalyst to that of H2O2 (1: 0.3 to 1: 0.7). More than 90 % of phenol removal and more than 40% of TOC removal were achieved within 60 minutes of reaction. Two separate models were developed using artificial neural networks to predict degradation percentage by a combination of Fe3+ and Fe2+ catalyst. Five operational parameters were employed as inputs while phenol degradation and TOC removal were considered as outputs of the developed models. Satisfactory agreement was observed between testing data and the predicted values (R2 Phenol = 0.9214 and R2TOC= 0.9082). PMID:25849556

Synthesis and analytical follow-up of the mineralization of a new fluorosurfactant prototype.

PubMed

Peschka, M; Fichtner, N; Hierse, W; Kirsch, P; Montenegro, E; Seidel, M; Wilken, R D; Knepper, T P

2008-08-01

Fluorinated surfactants have become essential in numerous technical applications due to their unparalleled effectiveness and efficiency. The environmental persistence of the non-biodegradable perfluorinated alkyl moiety has become a matter of concern. Therefore, it was searched for new molecules with chemically stable fluorinated end groups which can be microbially transformed into labile fluorinated substances. One prototype substance, 10-(trifluoromethoxy)decane-1-sulfonate, has shown biomineralization. Monitoring the formation of metabolites over time elucidated the mechanism of biotransformation. Analysis was performed utilizing liquid chromatography-single quadrupole mass spectrometry (LC-MS) and quadrupole-time of flight tandem mass spectrometry (QqTOF-MS). It was possible to distinguish between two major degradation pathways of the fluorinated alkylsulfonate derivative: (i) a desulfonation and subsequent oxidation and degradation of the alkyl chain being predominant and (ii) an insertion of oxygen with a subsequent cleavage and degradation of the molecule. The utilized trifluoromethoxy-endgroup resulted in instable trifluoromethanol after degradation of the alkyl chain, which led to a high degree of mineralization of the molecule.

Self-sensitization of tetracycline degradation with simulated solar light catalyzed by ZnO@montmorillonite

NASA Astrophysics Data System (ADS)

Zyoud, Ahed; Jondi, Waheed; AlDaqqah, Najat; Asaad, Sara; Qamhieh, Naser; Hajamohideen, AbdulRazack; Helal, Muath H. S.; Kwon, Hansang; Hilal, Hikmat S.

2017-12-01

Zinc oxide (ZnO) nano-particles were chemically deposited onto montmorillonite (MONT) clay particles. The composite ZnO@MONT was then characterized and used as a catalyst for photo-degradation of aqueous tetracycline. Unlike earlier studies, solar simulated light can be effectively used in this work. The composite shows high efficiency as adsorbent and as a photo-degradation catalyst. Both adsorbed and dissolved tetracycline molecules undergo mineralization under the photo-catalytic conditions, and up to 94% of the contaminant gross amount is completely mineralized. Other forms of ZnO particles, commercial ZnO and synthetic ZnO particles were examined in separate experiments. The ZnO@MONT is superior to both pristine counterparts. The ability of tetracycline to sensitize the supported ZnO particles, to solar simulated light, before being photo-degraded itself, is discussed here for the first time. In addition to enhanced catalytic activity of the ZnO@MONT, the composite can be efficiently recovered and reused with no significant loss of efficiency.

Understanding of Materials State and its Degradation using Non-Linear Ultrasound (NLU) Approaches

DTIC Science & Technology

2011-01-01

Traditional ultrasonic NDE is based on linear theory and normally relies on measuring some particular parameter (sound velocity , attenuation... velocity in the material. In most cases this technique is not considered to be very practical as very small changes in velocity has to be measured. Hence...nonlinear elasticity) of the material the input wave distorts as it propagates. This is attributed to the difference in the wave velocities of the

Rock weathering by indigenous heterotrophic bacteria of Bacillus spp. at different temperature: a laboratory experiment

NASA Astrophysics Data System (ADS)

Štyriaková, I.; Štyriak, I.; Oberhänsli, H.

2012-07-01

The bio-weathering of basalt, granite and gneiss was experimentally investigated in this study. These rock-forming minerals weathered more rapidly via the ubiquitous psychrotrophic heterotrophic bacteria . With indigenous bacteria of Bacillus spp. from sediments of Lake Baikal, we traced the degradation process of silicate minerals to understand the weathering processes occurring at the change temperature in the subsurface environment with organic input. The bacteria mediated dissolution of minerals was monitored with solution and solid chemistry, X-ray analyses as well as microscopic techniques. We determined the impact of the bacteria on the mineral surface and leaching of K, Ca, Mg, Si, Fe, and Al from silicate minerals. In the samples the release of major structural elements of silicates was used as an overall indicator of silicate mineral degradation at 4°C and 18°C from five medium exchanges over 255 days of rock bioleaching. The increase of temperature importantly affected the efficiency of Fe extraction from granite and basalt as well as Si extraction from granite and gneiss. In comparison with elemental extraction order at 4°C, Ca was substituted first by Fe or Si. It is evident that temperature influences rock microbial weathering and results in a change of elements extraction.

Laboratory ultrasonic pulse velocity logging for determination of elastic properties from rock core

NASA Astrophysics Data System (ADS)

Blacklock, Natalie Erin

During the development of deep underground excavations spalling and rockbursting have been recognized as significant mechanisms of violent brittle failure. In order to predict whether violent brittle failure will occur, it is important to identify the location of stiffness transitions that are associated with geologic structure. One approach to identify the effect of geologic structures is to apply borehole geophysical tools ahead of the tunnel advance. Stiffness transitions can be identified using mechanical property analysis surveys that combine acoustic velocity and density data to calculate acoustic estimates of elastic moduli. However, logistical concerns arise since the approach must be conducted at the advancing tunnel face. As a result, borehole mechanical property analyses are rarely used. Within this context, laboratory ultrasonic pulse velocity testing has been proposed as a potential alternative to borehole mechanical property analysis since moving the analysis to the laboratory would remove logistical constraints and improve safety for the evaluators. In addition to the traditional method of conducting velocity testing along the core axis, two new methodologies for point-focused testing were developed across the core diameter, and indirectly along intact lengths of drill core. The indirect test procedure was implemented in a continuous ultrasonic velocity test program along 573m of drill core to identify key geologic structures that generated transitions in ultrasonic elastic moduli. The test program was successful at identifying the location of geologic contacts, igneous intrusions, faults and shear structures. Ultrasonic values of Young's modulus and bulk modulus were determined at locations of significant velocity transitions to examine the potential for energy storage and energy release. Comparison of results from different ultrasonic velocity test configurations determined that the indirect test configuration provided underestimates for values of Young's modulus. This indicated that the test procedure will require modifications to improve coupling of the transducers to the core surface. In order to assess whether laboratory testing can be an alternative to borehole surveys, laboratory velocity testing must be directly assessed with results from acoustic borehole logging. There is also potential for the laboratory velocity program to be used to assess small scale stiffness changes, differences in mineral composition and the degree of fracturing of drill core.

Dichloroethene and Vinyl Chloride Degradation Potential in Wetland Sediments at Twin Lakes and Pen Branch, Savannah River National Laboratory, South Carolina

USGS Publications Warehouse

Bradley, Paul M.

2007-01-01

A series of 14C-radiotracer-based microcosm experiments was conducted to assess the mechanisms and products of degradation of dichloroethene (DCE) and vinyl chloride (VC) in wetland sediments at the Department of Energy (DOE) Savannah River National Laboratory. This project investigated the potential for biotic and abiotic DCE and VC degradation in wetland sediments from the Twin Lakes area of the C-BRP investigative unit and from the portion of Pen Branch located directly down gradient from the CMP investigative unit. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC to 14CO2 was observed in all viable sediment microcosms prepared under oxic conditions. These results indicate that microbial mineralization processes, involving direct oxidation or cometabolic oxidation, are the primary mechanisms of DCE and VC biodegradation in Twin Lake and Pen Branch sediments under oxic conditions. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC was observed in all viable sediment microcosms incubated under anoxic conditions. Production of 14CO2 was observed in all sediment microcosms under anoxic conditions. In general, the accumulation of mineralization products (14CO2 and 14CH4) was comparable to the accumulation of those reduced daughter products (14C-VC, 14C-ethene or 14C-ethane) traditionally identified with chloroethene reductive dechlorination. These results indicate that microbial mineralization processes can be an important component of DCE and VC degradation in Twin Lake and Pen Branch sediments under anoxic conditions. These results demonstrate that an evaluation of the efficiency of in situ DCE and VC biodegradation in Twin Lakes and Pen Branch that is based solely on the observed accumulation of reduced daughter products may underestimate substantially the total extent of contaminant biodegradation and, thus, the contribution of biodegradation to overall contaminant attenuation. No evidence of abiotic degradation of [1,2-14C] DCE or [1,2-14C] VC was observed in heat-sterilized control treatments in this study under oxic or anoxic conditions. Efforts to enrich and isolate microorganisms involved in the mineralization of [1,2-14C] cis-DCE and/or [1,2-14C] VC were unsuccessful.

Mineralization of aniline using hydroxyl/sulfate radical-based technology in a waterfall reactor.

PubMed

Durán, A; Monteagudo, J M; San Martín, I; Amunategui, F J; Patterson, D A

2017-11-01

The aim of this work is to study the applicability of a UV/H 2 O 2 process intensified with persulfate (PS) as a source of SO 4 - radicals to efficiently mineralize a synthetic effluent containing aniline in a glass reactor arranged in a cascade configuration. pH conditions were studied and the concentration of PS was optimized. The synergism for aniline mineralization between the UV/H 2 O 2 process and the combined UV/H 2 O 2 /PS process was quantified in 10.1%. Aniline degradation reached 100% under the UV/H2O2/PS process after 20 min. Its mineralization is favored under acidic conditions and with the presence of persulfate (optimal conditions: 49% in 90 min; pH = 4; [PS] = 250 ppm). On the contrary, the worst conditions were found at pH = 11, since hydrogen peroxide decomposes and carbonates were formed increasing the scavenging effect. The different mechanisms involved (formulated from intermediates identified by mass spectrometry) confirm these results. Aniline was found to follow a degradation pathway where phenol is the main intermediate. The presence of sulfate radicals increases phenol degradation rate leading to a higher mineralization extent. Benzoquinone was identified as the main aromatic oxidation product of phenol, whereas succinic, 4-oxo-pentanoic, fumaric and oxalic acids were detected as aliphatic oxidation products for both UV/H2O2 and UV/H2O2/PS oxidation processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Piezosurgery to perform hyoid bone osteotomies in thyroglossal duct cyst surgery.

PubMed

Salgarelli, Attilio Carlo; Robiony, Massimo; Consolo, Ugo; Collini, Marco; Bellini, Pierantonio

2011-11-01

Ultrasonic bone-cutting surgery has been introduced as a feasible alternative to the conventional sharp instruments used in craniomaxillofacial surgery because of its precision and safety. The device used is unique in that the cutting action occurs when the tool is used on mineralized tissues and stops on soft tissues. This work describes the use of piezosurgery for hyoid bone resection in thyroglossal duct cyst surgery, briefly reviews the literature on the surgical technique, and reports our experience with 12 cases.

Controlling Fluid Flow in the Subsurface through Ureolysis-Controlled Mineral Precipitation

NASA Astrophysics Data System (ADS)

Gerlach, R.; Phillips, A. J.; Cunningham, A. B.; Spangler, L.

2016-12-01

In situ urea hydrolysis has been used by us successfully to manipulate the carbonate alkalinity and control the precipitation of carbonate minerals. Urea hydrolysis can be promoted using microbial cells, enzymes or thermal energy. This technology can be used to mitigate leakage pathways, seal fractures or control fluid transport in the subsurface in hydrocarbon production, enhanced geothermal energy storage, carbon sequestration, nuclear waste disposal, etc. We have completed two field demonstrations of the urea hydrolysis-controlled in situ mineral precipitation technology. The first demonstration showed fracture sealing was possible in a sandstone formation approx. 1120' below ground surface (bgs) and that the fracture had increased resistance to re-fracturing after mineralization treatment. The second field demonstration was performed in a well with an identified channel in the cement near the wellbore at approx. 1020' bgs. The in situ mineralization treatment resulted in reduced pressure decay during shut in periods and reduced injectivity. In addition, a noticeable difference was observed in the solids percentage in the ultrasonic imaging logs before and after biomineralization treatment. The presentation will summarize and put into context the field and our recent laboratory research focusing on permeability manipulation using the in situ ureolysis-driven mineralization technology under ambient and subsurface pressure conditions. We have demonstrated permeability reductions of 3-6 orders of magnitude in 100 µm to 4mm gaps between shale, sandstone and cement/steel interfaces.

Antibiotics do not affect the degradation of fungicides and enhance the mineralization of chlorpyrifos in biomixtures.

PubMed

Castillo-González, Humberto; Pérez-Villanueva, Marta; Masís-Mora, Mario; Castro-Gutiérrez, Víctor; Rodríguez-Rodríguez, Carlos E

2017-05-01

The use of antibiotics in agriculture produces residues in wastewaters. The disposal of such wastewaters in biopurification systems (BPS) employed for the treatment of pesticides could result in the inhibition of the degrading capacity of the biomixtures used in the BPS. We assayed the effect of two commercial formulations of antibiotics used in agriculture, one containing kasugamycin (KSG) and the other oxytetracycline plus gentamicin (OTC+GTM), on the biomixture performance. Doses from 0.1mgkg -1 to 1000mgkg -1 of KSG increased the respiration of the biomixture, and low doses enhanced the mineralization rate of the insecticide 14 C-chlorpyrifos. On the contrary, OTC+GTM depressed the respiration of the biomixture and the initial mineralization rate of 14 C-chlorpyrifos; nonetheless, the antibiotics did not decrease overall mineralization values. The application of both formulations in the biomixture at a relevant concentration did not harm the removal of the fungicides carbendazim and metalaxyl, or their enhanced degradation; on the other hand, the biomixture was unable to dissipate tebuconazol or triadimenol, a result that was unchanged during the addition of the antibiotic formulations. These findings reveal that wastewater containing these antibiotics do not affect the performance of BPS. However, such a response may vary depending on the type of pesticide and microbial consortium in the biomixture. Copyright © 2017 Elsevier Inc. All rights reserved.

Rapid and solvent-saving liquefaction of woody biomass using microwave-ultrasonic assisted technology.

PubMed

Lu, Zexiang; Wu, Zhengguo; Fan, Liwei; Zhang, Hui; Liao, Yiqiang; Zheng, Deyong; Wang, Siqun

2016-01-01

A novel process to rapidly liquefy sawdust using reduced quantities of solvent, was successfully carried out via microwave-ultrasonic assisted technology (MUAT) in a sulphuric acid/polyethylene glycol 400-glycerol catalytic system. The influences of some key parameters on the liquefaction yield were investigated. The results showed that compared with traditional liquefaction, the introduction of MUAT allowed the solvent dosage to be halved and shortened the liquefaction time from 60 to 20 min. The liquefaction yield reached 91% under the optimal conditions. However, the influence on the yield of some parameters such as catalyst concentration, was similar to that of traditional liquefaction, indicating that the application of MUAT possibly only intensified heat and mass transfer rather than altering either the degradation mechanism or pathway. The introduction of MUAT as a process intensification technology has good industrial application potential for woody biomass liquefaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pretreatment combining ultrasound and sodium percarbonate under mild conditions for efficient degradation of corn stover.

PubMed

Nakashima, Kazunori; Ebi, Yuuki; Kubo, Masaki; Shibasaki-Kitakawa, Naomi; Yonemoto, Toshikuni

2016-03-01

Ultrasound (US) can be used to disrupt microcrystalline cellulose to give nanofibers via ultrasonic cavitation. Sodium percarbonate (SP), consisting of sodium carbonate and hydrogen peroxide, generates highly reactive radicals, which cause oxidative delignification. Here, we describe a novel pretreatment technique using a combination of US and SP (US-SP) for the efficient saccharification of cellulose and hemicellulose in lignocellulosic corn stover. Although US-SP pretreatment was conducted under mild condition (i.e., at room temperature and atmospheric pressure), the pretreatment greatly increased lignin removal and cellulose digestibility. We also determined the optimum US-SP treatment conditions, such as ultrasonic power output, pretreatment time, pretreatment temperature, and SP concentration for an efficient cellulose saccharification. Moreover, xylose could be effectively recovered from US-SP pretreated biomass without the formation of microbial inhibitor furfural. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultrasonic synthesis of In-doped SnS nanoparticles and their physical properties

NASA Astrophysics Data System (ADS)

Jamali-Sheini, Farid; Cheraghizade, Mohsen; Yousefi, Ramin

2018-05-01

Indium (In)-doped Tin (II) Sulfide (SnS) nanoparticles (NPs) were synthesized by an ultra-sonication method and their optical, electrical, dielectric and photocatalytic properties were investigated. XRD patterns of the obtained NPs indicated formation of orthorhombic polycrystalline SnS. Field emission scanning electron microscopy exhibited flower-like NPs with particle sizes below 100 nm for both SnS and In-doped SnS samples. Optical analysis showed a decrease in energy band gap of SnS NPs upon In doping. In addition, electrical results demonstrated p-type nature of the synthesized SnS NPs and enhanced electrical conductivity of the NPs due to increased tin vacancy. Dielectric experiments on SnS NPs suggested an electronic polarizations effect to be responsible for changing dielectric properties of the particles, in terms of frequency. Finally, photocatalytic experiments revealed that high degradation power can be obtained using In-doped SnS NPs.

A guided wave dispersion compensation method based on compressed sensing

NASA Astrophysics Data System (ADS)

Xu, Cai-bin; Yang, Zhi-bo; Chen, Xue-feng; Tian, Shao-hua; Xie, Yong

2018-03-01

The ultrasonic guided wave has emerged as a promising tool for structural health monitoring (SHM) and nondestructive testing (NDT) due to their capability to propagate over long distances with minimal loss and sensitivity to both surface and subsurface defects. The dispersion effect degrades the temporal and spatial resolution of guided waves. A novel ultrasonic guided wave processing method for both single mode and multi-mode guided waves dispersion compensation is proposed in this work based on compressed sensing, in which a dispersion signal dictionary is built by utilizing the dispersion curves of the guided wave modes in order to sparsely decompose the recorded dispersive guided waves. Dispersion-compensated guided waves are obtained by utilizing a non-dispersion signal dictionary and the results of sparse decomposition. Numerical simulations and experiments are implemented to verify the effectiveness of the developed method for both single mode and multi-mode guided waves.

Sonocatalytic degradation of malachite green oxalate by a semiconductor metal oxide nanocatalyst.

PubMed

Bhavani, R; Sivasamy, A

2016-12-01

Advanced Oxidation Process (AOP) technologies are considered to be better technique for the degradation or mineralization of many recalcitrant compounds and pollutants. In the present study heterogeneous sonocatalytic degradation of a model organic compound such as Malachite green oxalate (MGO) was carried out in the aqueous phase. Zinc oxide nanorods were prepared by precipitation method employing zinc acetates as precursors and were characterized by FT-IR, XRD, FE-SEM and EDAX analysis. Degradation of MGO in the aqueous phase was studied in detail under the sonocatalytic process. Effects of pH, dye concentration, oxidant concentration, kinetics and effect of electrolytes on dye degradation were carried out to check the efficiency of the sonocatalyst. Effect of energy input on the degradation processes was also investigated. The degradation of dye molecules were monitored by UV-visible spectrophotometer and Chemical Oxygen demand (COD). The dye molecules were readily degraded at above 90% in the pH range 5.0-7.0 under ultrasound with zinc oxide nanorods. The interference of electrolytes like NaCl, KCl, Na 2 CO 3 , NaHCO 3 and MgSO 4 on the degradation of dye molecules were also studied on the sonocatalytic degradation of MGO. From the kinetic studies it was observed that at lower initial concentration of dye molecules the degradation efficiency was above 90%. The rate of the reaction decreased on increasing the initial dye concentrations of the dye molecules. It was observed that the complete mineralization of dye molecules was achieved without the formation of toxic by-products. The reusability of the catalyst also showed the effective degradation of the dye molecules up to five cycles without loss of the catalytic activities. Copyright © 2015 Elsevier Inc. All rights reserved.

Dynamic mechanical properties and anisotropy of synthetic shales with different clay minerals under confining pressure

NASA Astrophysics Data System (ADS)

Gong, Fei; Di, Bangrang; Wei, Jianxin; Ding, Pinbo; Shuai, Da

2018-03-01

The presence of clay minerals can alter the elastic behaviour of reservoir rocks significantly as the type of clay minerals, their volume and distribution, and their orientation control the shale's intrinsic anisotropic behaviours. Clay minerals are the most abundant materials in shale, and it has been proven extremely difficult to measure the elastic properties of natural shale by means of a single variable (in this case, the type of clay minerals), due to the influences of multiple factors, including water, TOC content and complex mineral compositions. We used quartz, clay (kaolinite, illite and smectite), carbonate and kerogen extract as the primary materials to construct synthetic shale with different clay minerals. Ultrasonic experiments were conducted to investigate the anisotropy of velocity and mechanical properties in dry synthetic and natural shale as a function of confining pressure. Velocities in synthetic shale are sensitive to the type of clay minerals, possibly due to the different structures of the clay minerals. The velocities increase with confining pressure and show higher rate of velocity increase at low pressures, and P-wave velocity is usually more sensitive than S-wave velocity to confining pressure according to our results. Similarly, the dynamic Young's modulus and Poisson's ratio increase with applied pressure, and the results also reveal that E11 is always larger than E33 and ν31 is smaller than ν12. Velocity and mechanical anisotropy decrease with increasing stress, and are sensitive to stress and the type of clay minerals. However, the changes of mechanical anisotropy with applied stress are larger compared with the velocity anisotropy, indicating that mechanical properties are more sensitive to the change of rock properties.

SERDP ER-1421 Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA: Final Report

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

Szecsody, James E.; McKinley, James P.; Crocker, Fiona H.

This laboratory-scale project was initiated to investigate in situ abiotic/biotic mineralization of NDMA. Under iron-reducing conditions, aquifer sediments showed rapid abiotic NDMA degradation to dimethylamine (DMA), nitrate, formate, and finally, CO2. These are the first reported experiments of abiotic NDMA mineralization. The NDMA reactivity of these different iron phases showed that adsorbed ferrous iron was the dominant reactive phase that promoted NDMA reduction, and other ferrous phases present (siderite, iron sulfide, magnetite, structural ferrous iron in 2:1 clays) did not promote NDMA degradation. In contrast, oxic sediments that were biostimulated with propane promoted biomineralization of NDMA by a cometabolic monooxygenasemore » enzyme process. Other monooxygenase enzyme processes were not stimulated with methane or toluene additions, and acetylene addition did not block mineralization. Although NDMA mineralization extent was the highest in oxic, biostimulated sediments (30 to 82%, compared to 10 to 26% for abiotic mineralization in reduced sediments), large 1-D column studies (high sediment/water ratio of aquifers) showed 5.6 times higher NDMA mineralization rates in reduced sediment (half-life 410 ± 147 h) than oxic biomineralization (half life 2293 ± 1866 h). Sequential reduced/oxic biostimulated sediment mineralization (half-life 3180 ± 1094 h) was also inefficient compared to reduced sediment. These promising laboratory-scale results for NDMA mineralization should be investigated at field scale. Future studies of NDMA remediation should focus on the comparison of this in situ abiotic NDMA mineralization (iron-reducing environments) to ex situ biomineralization, which has been shown successful in other studies.« less

Sonochemical degradation of endocrine-disrupting organochlorine pesticide Dicofol: Investigations on the transformation pathways of dechlorination and the influencing operating parameters.

PubMed

Debabrata, Panda; Sivakumar, Manickam

2018-08-01

Dicofol, an extensively used organochlorine pesticide and a recommended Stockholm convention persistent organic pollutant (POP) candidate is well known for its endocrine disruptive properties. The sonochemical degradation of Dicofol in aqueous media has been investigated using a 20-kHz probe type sonicator with power inputs from 150 to 450 W. The degradation rate was determined as a function of concentration of Dicofol, solution pH, bulk phase temperature, ultrasonic power density and H 2 O 2 addition. At optimum operating conditions, the pseudo-first-order degradation rate constant (k) was determined to be 0.032 min -1 and the extent of degradation was found to be 86% within 60 min of ultrasound treatment. High performance liquid chromatography (HPLC) and Gas chromatography coupled with mass spectroscopy (GC-MS) analysis indicated the presence of degraded products. The obtained results of Dicofol degradation and control experiments in the presence of H 2 O 2 and radical scavenger test suggest thermal decomposition along with radical attack at bubble-vapor interface to be the dominant degradation pathway. Sonochemical treatment is effective and promising for successful removal of harmful pesticides such as Dicofol and superior removal efficiency for other POPs is expected in the near future with the successful implementation of ultrasound-based wastewater treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway.

PubMed

Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

2017-01-01

In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H 2 O 2 and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H 2 O 2 at a dye to H 2 O 2 molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5-10min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Products from the incomplete metabolism of pyrene by polycyclic aromatic hydrocarbon-degrading bacteria

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

Kazunga, C.; Aitken, M.D.

Pyrene is a regulated pollutant at sites contaminated with polycyclic aromatic hydrocarbons (PAH). It is mineralized by some bacteria but is also transformed to nonmineral products by a variety of other PAH-degrading bacteria. The authors examined the formation of such products by four bacterial strains and identified and further characterized the most apparently significant of these metabolites. Pseudomonas stutzeri strain P16 and Bacillus cereus strain P21 transformed pyrene primarily to cis-4,5-dihydro-4,5-dihydroxypyrene (PYRdHD), the first intermediate in the known pathway for aerobic bacterial mineralization of pyrene. Sphingomonas yanoikuyae strain R1 transformed pyrene to PYRdHD and pyrene-4,5-dione (PYRQ). Both strain R1 andmore » Pseudomonas saccharophila strain P15 transform PYRdHD to PYRQ nearly stoichiometrically, suggesting that PYRQ is formed by oxidation of PYRdHD to 4,5-dihydroxypyrene and subsequent autoxidation of this metabolite. A pyrene-mineralizing organism, Mycobacterium strain PYR-1, also transforms PYRdHD to PYRQ at high initial concentrations of PYRdHD. However, strain PYR-1 is able to use both PYRdHD and PYRQ as growth substrates. PYRdHD strongly inhibited phenanthrene degradation by strains P15 and R1 but had only a minor effect on strains P16 and P21. At their aqueous saturation concentrations, both PYRdHD and PYRQ severely inhibited benzo[a]pyrene mineralization by strains P15 and R1. Collectively, these findings suggest that products derived from pyrene transformation have the potential to accumulate in PAH-contaminated systems and that such products can significantly influence the removal of other PAH. However, these products may be susceptible to subsequent degradation by organisms able to metabolize pyrene more extensively if such organisms are present in the system.« less

Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

NASA Astrophysics Data System (ADS)

Lü, Dongwei; Song, Qian; Wang, Xuchen

2010-01-01

A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components (14:0, 16:0, 16:1, 18:1 and 20:5), and n-alkanes (C16-C23) were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017-0.024 d-1, 0.049-0.103 d-1 and 0.011 to 0.069 d-1, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.

Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 2. Role of Gut Microorganisms.

PubMed

Yang, Yu; Yang, Jun; Wu, Wei-Min; Zhao, Jiao; Song, Yiling; Gao, Longcheng; Yang, Ruifu; Jiang, Lei

2015-10-20

The role of gut bacteria of mealworms (the larvae of Tenebrio molitor Linnaeus) in polystyrene (PS) degradation was investigated. Gentamicin was the most effective inhibitor of gut bacteria among six antibiotics tested. Gut bacterial activities were essentially suppressed by feeding gentamicin food (30 mg/g) for 10 days. Gentamicin-feeding mealworms lost the ability to depolymerize PS and mineralize PS into CO2, as determined by characterizing worm fecula and feeding with (13)C-labeled PS. A PS-degrading bacterial strain was isolated from the guts of the mealworms, Exiguobacterium sp. strain YT2, which could form biofilm on PS film over a 28 day incubation period and made obvious pits and cavities (0.2-0.3 mm in width) on PS film surfaces associated with decreases in hydrophobicity and the formation of C-O polar groups. A suspension culture of strain YT2 (10(8) cells/mL) was able to degrade 7.4 ± 0.4% of the PS pieces (2500 mg/L) over a 60 day incubation period. The molecular weight of the residual PS pieces was lower, and the release of water-soluble daughter products was detected. The results indicated the essential role of gut bacteria in PS biodegradation and mineralization, confirmed the presence of PS-degrading gut bacteria, and demonstrated the biodegradation of PS by mealworms.

Biodegradation of Fresh vs. Oven-Dried Inedible Crop Residue in a Continuously Stirred Tank Reactor

NASA Technical Reports Server (NTRS)

Crawford, Kamau; Strayer, Richard

1998-01-01

The degradation of soluble organics and mineral recovery from fresh and oven-dried biomass were compared in an Intermediate-Scale Aerobic Bioreactor (8 L working volume) to determine if drying crop residue improves performance in a continuously stirred tank reactor (CSTR). The study was conducted in an Intermediate-Scale Aerobic Bioreactor (ISAB) CSTR with dimensions of 390 mm height x 204 mm diameter. The pH in the bioreactor was controlled at 6.0, temperature at 30 C, and aeration at 7.0 L/min. Gases monitored were CO2 evolution and dissolved oxygen. Homogeneously mixed wheat cultures, used either fresh or oven-dried biomass and were leached, then placed in the ISAB for a 4-day degradation period. Studies found that mineral recovery was greater for leached oven-dried crop residue. However, after activity by the mixed microbial communities in the ISAB CSTR, there were little notable differences in the measured mineral recovery and degradation of soluble organic compounds. Degradation of soluble organic compounds was also shown to improve for leached oven-dried crop residue, but after mixing in the CSTR the degradation of the fresh biomass seemed to be slightly greater. Time for the biomass to turn in the CSTR appeared to be one factor for the experimental differences between the fresh and oven-dried biomass. Other factors, although not as defined, were the differing physical structures in the cell walls and varying microbial components of the fresh and oven-dried treatments due to changes in chemical composition after drying of the biomass.

Interaction, at Ambient Temperature and 80 °C, between Minerals and Artificial Seawaters Resembling the Present Ocean Composition and that of 4.0 Billion Years Ago.

PubMed

Carneiro, Cristine E A; Stabile, Antonio C; Gomes, Frederico P; da Costa, Antonio C S; Zaia, Cássia T B V; Zaia, Dimas A M

2017-09-01

Probably one of the most important roles played by minerals in the origin of life on Earth was to pre-concentrate biomolecules from the prebiotic seas. There are other ways to pre concentrate biomolecules such as wetting/drying cycles and freezing/sublimation. However, adsorption is most important. If the pre-concentration did not occur-because of degradation of the minerals-other roles played by them such as protection against degradation, formation of polymers, or even as primitive cell walls would be seriously compromised. We studied the interaction of two artificial seawaters with kaolinite, bentonite, montmorillonite, goethite, ferrihydrite and quartz. One seawater has a major cation and anion composition similar to that of the oceans of the Earth 4.0 billion years ago (ASW 4.0 Ga). In the other, the major cations and anions are an average of the compositions of the seawaters of today (ASWT). When ASWT, which is rich in Na + and Cl - , interacted with bentonite and montmorrilonite structural collapse occurred on the 001 plane. However, ASW 4.0 Ga, which is rich in Mg 2+ and SO 4 2- , did not induce this behavior. When ASW 4.0 Ga was reacted with the minerals for 24 h at room temperature and 80 °C, the release of Si and Al to the fluid was below 1 % of the amount in the minerals-meaning that dissolution of the minerals did not occur. In general, minerals adsorbed Mg 2+ and K + from the ASW 4.0 Ga and these cations could be used for the formation of polymers. Also, when the minerals were mixed with ASW 4.0 Ga at 80 °C and ASWT at room temperature or 80 °C it caused the precipitation of CaSO 4 ∙2H 2 O and halite, respectively. Finally, further experiments (adsorption, formation of polymers, protection of molecules against degradation, primitive cell wall formation) performed under the conditions described in this paper will probably be more representative of what happened on the prebiotic Earth.

Oxidation of 2,4-dichlorophenoxyacetic acid by ionizing radiation: degradation, detoxification and mineralization

NASA Astrophysics Data System (ADS)

Zona, Robert; Solar, Sonja

2003-02-01

The gamma-radiation-induced degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in aerated (A) and in during irradiation air saturated (AS) solutions. Whereas the decomposition rates were not influenced by AS, chloride elimination, detoxification as well as mineralization were significantly enhanced. In the range 50-500 μmol dm -3 2,4-D, degradation showed proportionality to concentration, while chloride formation was successively retarded. The ratios of the pseudo first-order rate constants for degradation and chloride formation, kde/ kCl, increase in AS solutions from 1.4 (50 μmol dm -3) to 2.7 (500 μmol dm -3) and in A solutions from 1.4 to 3.3. In AS for total chloride release 0.7 kGy (50 μmol dm -3) to 10 kGy (500 μmol dm -3) were required, the reduction of organic carbon at 10 kGy was 95% (50 μmol dm -3) and 50% (500 μmol dm -3). Increase and decrease of toxicity during irradiation correlated well with formation and degradation of intermediate phenolic products. The doses for detoxification corresponded to those of total dehalogenation. The oxygen uptake was ˜1.1 ppm 100 Gy -1. The presence of the inorganic components of Vienna drinking water affect the degradation parameters insignificantly.

Innovative approach for benzene degradation using hybrid surface/packed-bed discharge plasmas.

PubMed

Jiang, Nan; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

2013-09-03

An innovative plasma reactor, which generates hybrid surface/packed-bed discharge (HSPBD) plasmas, was employed for the degradation of benzene. The HSPBD reactor was found to display remarkably better benzene degradation, mineralization, and energy performance than surface or packed-bed discharge reactors alone. The degradation efficiency, CO2 selectivity, and energy yield in the HSPBD reactor were 21%, 11%, and 3.9 g kWh-1 higher, respectively, than in a surface discharge reactor and 30%, 21%, and 5.5 g kWh-1 higher, respectively, than in a packed-bed discharge reactor operated at 280 J L-1. Particularly, the benzene degradation in the HSPBD reactor exhibited an unambiguous synergistic enhancement rather than a simple additive effect using the surface discharge and packed-bed discharge reactors. Moreover, in the HSPBD reactor, the formation of byproducts, such as NO2, was suppressed, while O3 was promoted. The use of N2 as the carrier gas was found to be effective for benzene degradation because of the fast reaction rate of N2(A3∑u+) with benzene, and oxygen species derived from the dissociation of O2 were found to be significant in the mineralization process. Thus, the addition of O2 to N2 allows for efficient degradation of benzene, and the optimized amount of O2 was determined to be 3%.

UV-induced photocatalytic degradation of aqueous acetaminophen: the role of adsorption and reaction kinetics.

PubMed

Basha, Shaik; Keane, David; Nolan, Kieran; Oelgemöller, Michael; Lawler, Jenny; Tobin, John M; Morrissey, Anne

2015-02-01

Nanostructured titania supported on activated carbon (AC), termed as integrated photocatalytic adsorbents (IPCAs), were prepared by ultrasonication and investigated for the photocatalytic degradation of acetaminophen (AMP), a common analgesic and antipyretic drug. The IPCAs showed high affinity towards AMP (in dark adsorption studies), with the amount adsorbed proportional to the TiO2 content; the highest adsorption was at 10 wt% TiO2. Equilibrium isotherm studies showed that the adsorption followed the Langmuir model, indicating the dependence of the reaction on an initial adsorption step, with maximum adsorption capacity of 28.4 mg/g for 10 % TiO2 IPCA. The effects of initial pH, catalyst amount and initial AMP concentration on the photocatalytic degradation rates were studied. Generally, the AMP photodegradation activity of the IPCAs was better than that of bare TiO2. Kinetic studies on the photocatalytic degradation of AMP under UV suggest that the degradation followed Langmuir-Hinshelwood (L-H) kinetics, with an adsorption rate constant (K) that was considerably higher than the photocatalytic rate constant (k r), indicating that the photocatalysis of AMP is the rate-determining step during the adsorption/photocatalysis process.

Sonocatalytic degradation of azo fuchsine in the presence of the Co-doped and Cr-doped mixed crystal TiO2 powders and comparison of their sonocatalytic activities.

PubMed

Wang, Jun; Lv, Yanhui; Zhang, Zhaohong; Deng, Yingqiao; Zhang, Liquan; Liu, Bin; Xu, Rui; Zhang, Xiangdong

2009-10-15

In order to degrade some pollutants effectively under ultrasonic irradiation, the Co-doped and Cr-doped mixed crystal TiO(2) powders, with high sonocatalytic activity, were prepared as sonocatalyst. The Co-doped and Cr-doped mixed crystal TiO(2) powders as sonocatalyst were prepared through sol-gel and heat-treated methods from tetrabutylorthotitanate, and then were characterized by XRD and TG-DTA technologies. In order to compare and evaluate the sonocatalytic activity of the Co-doped and Cr-doped mixed crystal TiO(2) powders, the low power ultrasound was as an irradiation source and the azo fuchsine was chosen as a model compound to be degraded. The degradation process was investigated by UV-vis, TOC, ion chromatogram and HPLC techniques. The results indicated that the sonocatalytic activity of Cr-doped mixed crystal TiO(2) powder was higher than that of Co-doped and undoped mixed crystal TiO(2) powder during the sonocatalytic degradation of the azo fuchsine in aqueous solution. These results may be of great significance for driving sonocatalytic method to treat non- or low-transparent industrial wastewaters.

Sunlight-driven photocatalytic degradation of non-steroidal anti-inflammatory drug based on TiO₂ quantum dots.

PubMed

Kaur, Amandeep; Umar, Ahmad; Kansal, Sushil Kumar

2015-12-01

This paper reports the facile synthesis, characterization and solar-light driven photocatalytic degradation of TiO2 quantum dots (QDs). The TiO2 QDs were synthesized by a facile ultrasonic-assisted hydrothermal process and characterized in terms of their structural, morphological, optical and photocatalytic properties. The detailed studies confirmed that the prepared QDs are well-crystalline, grown in high density and exhibiting good optical properties. Further, the prepared QDs were efficiently used as effective photocatalyst for the sun-light driven photocatalytic degradation of ketorolac tromethamine, a well-known non-steroidal anti-inflammatory drug (NSAID). To optimize the photocatalytic degradation conditions, various dose-dependent, pH-dependent, and initial drug-concentration dependent experiments were performed. The detailed solar-light driven photocatalytic experiments revealed that ∼99% photodegradation of ketorolac tromethamine drug solution (10 mg L(-1)) was observed with optimized amount of TiO2 QDs and pH (0.5 g L(-1) and 4.4, respectively) under solar-light irradiations. The observed results demonstrate that simply synthesized TiO2 QDs can efficiently be used for the solar-light driven photocatalytic degradation of harmful drugs and chemicals. Copyright © 2015 Elsevier Inc. All rights reserved.

Performance and Mechanism of Piezo-Catalytic Degradation of 4-Chlorophenol: Finding of Effective Piezo-Dechlorination.

PubMed

Lan, Shenyu; Feng, Jinxi; Xiong, Ya; Tian, Shuanghong; Liu, Shengwei; Kong, Lingjun

2017-06-06

Piezo-catalysis was first used to degrade a nondye pollutant, 4-chlorophenol (4-CP). In this process, hydrothermally synthesized tetragonal BaTiO 3 nano/micrometer-sized particles were used as the piezo-catalyst, and the ultrasonic irradiation with low frequency was selected as the vibration energy to cause the deformation of tetragonal BaTiO 3 . It was found that the piezoelectric potential from the deformation could not only successfully degrade 4-chlorophenol but also effectively dechlorinate it at the same time, and five kinds of dechlorinated intermediates, hydroquinone, benzoquinone, phenol, cyclohexanone, and cyclohexanol, were determined. This is the first sample of piezo-dechlorination. Although various active species, including h + , e - , •H, •OH, •O 2 - , 1 O 2 , and H 2 O 2 , were generated in the piezoelectric process, it was confirmed by ESR, scavenger studies, and LC-MS that the degradation and dechlorination were mainly attributed to •OH radicals. These •OH radicals were chiefly derived from the electron reduction of O 2 , partly from the hole oxidation of H 2 O. These results indicated that the piezo-catalysis was an emerging and effective advanced oxidation technology for degradation and dechlorination of organic pollutants.

Sonocatalytic degradation of an anthraquinone dye using TiO2-biochar nanocomposite.

PubMed

Khataee, Alireza; Kayan, Berkant; Gholami, Peyman; Kalderis, Dimitrios; Akay, Sema

2017-11-01

TiO 2 -biochar (TiO 2 -BC) nanocomposite was synthesized by sol-gel method. The characteristics of the prepared nanocomposite were examined using X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and N 2 adsorption-desorption analysis. The performance of synthesized TiO 2 -BC nanocomposite as efficient sonocatalyst was studied for the degradation of Reactive Blue 69 (RB69). Sonocatalytic degradation of RB69 in the presence of TiO 2 -BC nanocomposite could be explained by the mechanisms of hot spots and sonoluminescence. The optimized values for main operational parameters were determined as pH of 7, TiO 2 -BC dosage of 1.5g/L, RB69 initial concentration of 20mg/L and ultrasonic power of 300W. Furthermore, the effect of OH, h + and O 2 - scavengers on the RB69 degradation efficiency was studied. Gas chromatography-mass spectroscopy analysis was used to identify intermediate compounds formed during the RB69 degradation. The results of repeated applications of TiO 2 -BC in the sonocatalytic process verified its stability in long-term usage. Copyright © 2017 Elsevier B.V. All rights reserved.

Quorum Sensing Disruption in Vibrio harveyi Bacteria by Clay Materials.

PubMed

Naik, Sajo P; Scholin, Jonathon; Ching, San; Chi, Fang; Herpfer, Marc

2018-01-10

This work describes the use of clay minerals as catalysts for the degradation of quorum sensing molecule N-(3-oxooctanoyl)-dl-homoserine lactone. Certain clay minerals as a result of their surface properties and porosity can catalytically degrade the quorum sensing molecule into smaller fragments. The disruption of quorum sensing by clay in a growing Gram-negative Vibrio harveyi bacteria culture was also studied by monitoring luminescence and population density of the bacteria, wherein quenching of bacterial quorum sensing activity was observed by means of luminescence reduction. The results of this study show that food-grade clays can be used as biocatalysts in disrupting bacterial activity in various media.

Light scattering experiments on aqueous solutions of selected cellulose ethers: contribution to the study of polymer-mineral interactions in a new injectable biomaterial.

PubMed

Bohic, S; Weiss, P; Roger, P; Daculsi, G

2001-03-01

Hydroxypropylmethylcellulose (HPMC) is used as a ligand for a bioactive calcium phosphate ceramic (the filler) in a ready-to-use injectable sterilized biomaterial for bone and dental surgery. Light scattering experiments were usually used to study high water-soluble polymers and to determine the basic macromolecular parameters. In order to gain a deeper understanding of polymer/mineral interactions in this type of material, we have investigated the effect of divalent and trivalent ions (Ca(2+), PO(4)(3-)) and steam sterilization on dilute solutions of HPMC and hydroxyethylcellulose (HEC). The sterilization process may cause some degradation of HEC taking into account its high molecular weight and some rigidity of the polymer chain. Moreover, in the case of HPMC, the changes in the conformations rather than degradation process are supposed. These effects of degradation and flocculation are strengthened in alkaline medium. Experimental data suggested the formation of chelate complexes between Ca(2+) and HPMC which improve its affinity to the mineral blend and consolidate the injectable biomaterial even in the case of its hydration by biological fluid. Copyright 2001 Kluwer Academic Publishers

Validation of enhanced stabilization of municipal solid waste under controlled leachate recirculation using FTIR and XRD.

PubMed

Sethi, Sapna; Kothiyal, N C; Nema, Arvind K

2012-07-01

Leachate recirculation at neutral PH accompanied with buffer/nutrients addition has been used successfully in earlier stabilization of municipal solid waste in bioreactor landfills. In the present study, efforts were made to enhance the stabilization rate of municipal solid waste (MSW) and organic solid waste (OSW) in simulated landfill bioreactors by controlling the pH of recirculated leachate towards slightly alkaline side in absence of additional buffer and nutrients addition. Enhanced stabilization in waste samples was monitored with the help of analytical tools like Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). Predominance of bands assigned to inorganic compounds and comparatively lower intensities of bands for organic compounds in the FTIR spectra of waste samples degraded with leachate recirculation under controlled pH confirmed higher rate of biodegradation and mineralization of waste than the samples degraded without controlled leachate recirculation. XRD spectra also confirmed to a greater extent of mineralization in the waste samples degraded under leachate recirculation with controlled pH. Comparison of XRD spectra of two types of wastes pointed out higher degree of mineralization in organic solid waste as compared to municipal solid waste.

Internal loop photo-biodegradation reactor used for accelerated quinoline degradation and mineralization.

PubMed

Chang, Ling; Zhang, Yongming; Gan, Lu; Xu, Hua; Yan, Ning; Liu, Rui; Rittmann, Bruce E

2014-07-01

Biofilm biodegradation was coupled with ultra-violet photolysis using the internal loop photobiodegradation reactor for degradation of quinoline. Three protocols-photolysis alone (P), biodegradation alone (B), and intimately coupled photolysis and biodegradation (P&B)-were used for degradation of quinoline in batch and continuous-flow experiments. For a 1,000 mg/L initial quinoline concentration, the volumetric removal rate for quinoline was 38 % higher with P&B than with B in batch experiments, and the P&B kinetics were the sum of kinetics from the P and B experiments. Continuous-flow experiments with an influent quinoline concentration of 1,000 mg/L also gave significantly greater quinoline removal in P&B, and the quinoline-removal kinetics for P&B were approximately equal to the sum of the removal kinetics for P and B. P&B similarly increased the rate and extent of quinoline mineralization, for which the kinetics for P&B were nearly equal to the sum of kinetics for P and B. These findings support that the rate-limiting step for mineralization was transformation of quinoline, which was accelerated by the simultaneous action of photolysis and biodegradation.

Degradation of ampicillin antibiotic by electrochemical processes: evaluation of antimicrobial activity of treated water.

PubMed

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

2018-05-17

Ampicillin (AMP) is an antibiotic widely used in hospitals and veterinary clinics around the world for treating infections caused by bacteria. Therefore, it is common to find traces of this antibiotic in wastewater from these entities. In this work, we studied the mineralization of this antibiotic in solution as well as the elimination of its antimicrobial activity by comparing different electrochemical advanced oxidation processes (EAOPs), namely electro-oxidation with hydrogen peroxide (EO-H 2 O 2 ), electro-Fenton (EF), and photo electro-Fenton (PEF). With PEF process, a high degradation, mineralization, and complete elimination of antimicrobial activity were achieved in 120-min electrolysis with high efficiency. In the PEF process, fast mineralization rate is caused by hydroxyl radicals (·OH) that are generated in the bulk, on the anode surface, by UV radiation, and most importantly, by the direct photolysis of complexes formed between Fe 3+ and some organic intermediates. Moreover, some products and intermediates formed during the degradation of the antibiotic Ampicillin, such as inorganic ions, carboxylic acids, and aromatic compounds, were determined by photometric and chromatographic methods. An oxidation pathway is proposed for the complete conversion to CO 2 .

Aerobic secondary utilization of a non-growth and inhibitory substrate 2,4,6-trichlorophenol by Sphingopyxis chilensis S37 and sphingopyxis-like strain S32.

PubMed

Aranda, Carlos; Godoy, Félix; Becerra, José; Barra, Ricardo; Martínez, Miguel

2003-08-01

This paper reports 2,4,6-trichlorophenol (246TCP) degradation by Sphingopyxis chilensis S37 and Sphingopyxis chilensis-like strain S32, which were unable to use 246TCP as the sole carbon and energy source. In R2A broth, the strains degraded 246TCP up to 0.5 mM. Results with mixtures of different 246TCP and glucose concentrations in mineral salt media demonstrated dependence on glucose to allow bacterial growth and degradation of 246TCP. Strain S32 degraded halophenol up to 0.2 mM when 5.33 mM glucose was simultaneously added, while strain S37 degraded the compound up to 0.1 mM when 1.33 mM glucose was added. These 246TCP concentrations were lethal for inocula in absence of glucose. Stoichiometric releases of chloride and analysis by HPLC, GC-ECD and GC-MS indicated 246TCP mineralisation by both strains. To our knowledge, this is the first report of bacteria able to mineralize a chlorophenol as a non-growth and inhibitory substrate. The concept of secondary utilization instead of cometabolism is proposed for this activity.

An Ru(II)-Fe(III) bimetallic complex as a multifunctional device for detecting, signal amplifying, and degrading oxalate.

PubMed

Chow, Cheuk-Fai; Ho, Pui-Yu; Gong, Cheng-Bin

2014-09-07

A tetranuclear bimetallic complex, [Ru(II)((t)Bubpy)(CN)4]2-[Fe(III)(H2O)3Cl]2·8H2O (1) has been synthesized and characterized. It was found to be a multifunctional device that can detect, signal amplify, and degrade an organic pollutant, oxalate. Results of the chemosensing studies of 1 toward common anions show that only oxalate selectively induces naked-eye colorimetric and luminometric responses with method detection limits down to 78.7 and 5.5 ppm, respectively from 1. Meanwhile, results of the photo-degradation studies of 1 toward oxalate show that the dissolved organic carbon content of oxalate decreased and reached complete mineralization into CO2 within 6 hours. Complex 1 was also found as the catalyst that amplified the detection signal toward oxalate. Through the photoassisted Fenton reaction by 1, methyl orange, an additional coloring agent, could be degraded so that the visual detection limit of 1 toward oxalate was magnified 50 times from 100 to 2 ppm. The detection, degradation, mineralization and signal amplification were found applicable in real water bodies such as river, pond and underground water with excellent recoveries and relative standard deviation.

Ultrasonic-promoted rapid preparation of PVC/TiO2-BSA nanocomposites: Characterization and photocatalytic degradation of methylene blue.

PubMed

Mallakpour, Shadpour; Shamsaddinimotlagh, Sima

2018-03-01

In the present project in order to prevent agglomeration and better dispersion of TiO 2 nanoparticles (NPs) in the poly(vinyl chloride) (PVC) matrix, initially, the surface of TiO 2 NPs was covered by bovine serum albumin protein (BSA) via sonication method. Then, the TiO 2 -BSA powders were embedded into the PVC matrix using ultrasonic irradiations. With mechanical and magnetic stirring homogenous mixture was not obtained. So sonication process was very essential and vital. Physical, chemical and structural properties of the samples were investigated with various tools. Morphology studies showed the well distribution of spherical TiO 2 NPs in the PVC matrix. TGA analysis showed that nanocomposites (NCs) have higher thermal stability than the pristine polymer. The photocatalytic activity tests by destroying the methylene blue dye on the pristine TiO 2 NPs, TiO 2 -BSA NPs and PVC/TiO 2 -BSA NC 6 wt% were examined. The results showed that the photocatalytic activity of TiO 2 NPs was reduced in the presence of BSA and PVC. It can be concluded that the TiO 2 -BSA NPs and PVC/TiO 2 -BSA NC 6 wt% have UV shielding properties and can protect film from degradation by UV. Copyright © 2017 Elsevier B.V. All rights reserved.

Coupling between high-frequency ultrasound and solar photo-Fenton at pilot scale for the treatment of organic contaminants: an initial approach.

PubMed

Papoutsakis, Stefanos; Miralles-Cuevas, Sara; Gondrexon, Nicolas; Baup, Stéphane; Malato, Sixto; Pulgarin, César

2015-01-01

This study aims to evaluate the performance of a novel pilot-scale coupled system consisting of a high frequency ultrasonic reactor (400kHz) and a compound parabolic collector (CPC). The benefits of the concurrent application of ultrasound and the photo-Fenton process were studied in regard to the degradation behavior of a series of organic pollutants. Three compounds (phenol, bisphenol A and diuron) with different physicochemical properties have been chosen in order to identify possible synergistic effects and to obtain a better estimate of the general feasibility of such a system at field scale (10L). Bisphenol A and diuron were specifically chosen due to their high hydrophobicity, and thus their assumed higher affinity towards the cavitation bubble. Experiments were conducted under ultrasonic, photo-Fenton and combined treatments. Enhanced degradation kinetics were observed during the coupled treatment and synergy factors clearly in excess of 1 have been calculated for phenol as well as for saturated solutions of bisphenol A and diuron. Although the relatively high cost of ultrasound compared to photo-Fenton still presents a significant challenge towards mainstream industrial application, the observed behavior suggests that its prudent use has the potential to significantly benefit the photo-Fenton process, via the decrease of both treatment time and H2O2 consumption. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrasonic cavitation erosion-corrosion behavior of friction stir processed stainless steel.

PubMed

Selvam, Karthikeyan; Mandal, Priya; Grewal, Harpreet Singh; Arora, Harpreet Singh

2018-06-01

Cavitation erosion remains the primary cause of material degradation in fluid machinery components operating at high speed. Micro-jets/shock waves caused by implosion of bubbles on material surface results in significant material loss and premature failure of the components. The presence of corrosive medium further exuberates this effect, causing rapid degradation. Here, we demonstrate a novel pathway to control cavitation erosion-corrosion by tailoring the surface properties using submerged friction stir processing (FSP), a severe plastic deformation process. FSP parameters were varied over wide range of strain-rates to generate tailored microstructures. High strain-rate processing resulted in nearly single phase fine grained structure while low strain-rate processing resulted in phase transformation in addition to grain refinement. As-received and processed samples were subjected to ultrasonic cavitation in distilled water as well as in corrosive environment of 3.5% NaCl solution. Individual roles of cavitation erosion, corrosion and their synergistic effects were analyzed. Depending on the microstructure, processed samples showed nearly 4-6 times higher cavitation erosion resistance compared to as-received alloy. Superior cavitation erosion-corrosion resistance of processed samples was attributed to surface strengthening, higher strain-hardening ability and quick passivation kinetics. The results of current study could be potentially transformative in designing robust materials for hydro-dynamic applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of different advanced oxidation processes for the removal of amoxicillin in aqueous solution.

PubMed

Souza, Fernanda Siqueira; da Silva, Vanessa Vargas; Rosin, Catiusa Kuchak; Hainzenreder, Luana; Arenzon, Alexandre; Féris, Liliana Amaral

2018-03-01

Amoxicillin (AMX) is a widely used penicillin-type antibiotic whose presence in the environment has been investigated. In this work, the degradation of the AMX in aqueous solutions by ozonation, ozonation with UV radiation (O 3 /UV), homogeneous catalytic ozonation (O 3 /Fe 2+ ) and homogeneous photocatalytic ozonation (O 3 /Fe 2+ /UV) was investigated. The performance results have been compared in terms of removal of amoxicillin and total organic carbon (mineralization efficiency). In all processes, complete amoxicillin degradation was obtained after 5 min. However, low mineralization was achieved. For the best available process, the potential toxicity of AMX intermediates formed after ozonation was examined using a Fish Embryo Toxicity test. Results reveal that O 3 in alkaline solution and O 3 /Fe 2+ /UV provide the highest mineralization rates. Ecotoxicity showed that no acute toxicity was observed during the exposure period of 96 h.

Reduced biodegradability of desorption-resistant fractions of polycyclic aromatic hydrocarbons in soil and aquifer solids

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

White, J.C.; Alexander, M.

1996-11-01

Less of the desorption-resistant fractions of phenanthrene and naphthalene than freshly added phenanthrene and naphthalene was mineralized in columns of aquifer solids, loam, or muck. Slurrying columns of hydrocarbon-amended aquifer solids, loam, or muck enhanced the rate and extent of mineralization of desorption-resistant phenanthrene and naphthalene, but degradation was still less than in slurries amended with fresh compound. A substantial portion of the desorption-resistant compound remained undergraded in the slurry. A surfactant and methanol increased the mineralization of resistant phenanthrene in slurries of loam. A mixed culture of microorganisms enriched on desorption-resistant phenanthrene degraded twice as much of this fractionmore » of compound as a pseudomonad. The authors suggest that predictions of the environment fate of toxic chemicals require information on the biodegradability of the fraction of a compound that is resistant to desorption.« less

Nonlinear Wave Mixing Technique for Nondestructive Assessment of Infrastructure Materials

NASA Astrophysics Data System (ADS)

Ju, Taeho

To operate safely, structures and components need to be inspected or monitored either periodically or in real time for potential failure. For this purpose, ultrasonic nondestructive evaluation (NDE) techniques have been used extensively. Most of these ultrasonic NDE techniques utilize only the linear behavior of the ultrasound. These linear techniques are effective in detecting discontinuities in materials such as cracks, voids, interfaces, inclusions, etc. However, in many engineering materials, it is the accumulation of microdamage that leads to degradation and eventual failure of a component. Unfortunately, it is difficult for linear ultrasonic NDE techniques to characterize or quantify such damage. On the other hand, the acoustic nonlinearity parameter (ANLP) of a material is often positively correlated with such damage in a material. Thus, nonlinear ultrasonic NDE methods have been used in recently years to characterize cumulative damage such as fatigue in metallic materials, aging in polymeric materials, and degradation of cement-based materials due to chemical reactions. In this thesis, we focus on developing a suit of novel nonlinear ultrasonic NDE techniques based on the interactions of nonlinear ultrasonic waves, namely wave mixing. First, a noncollinear wave mixing technique is developed to detect localized damage in a homogeneous material by using a pair of noncollinear a longitudinal wave (L-wave) and a shear wave (S-wave). This pair of incident waves make it possible to conduct NDE from a single side of the component, a condition that is often encountered in practical applications. The proposed noncollinear wave mixing technique is verified experimentally by carrying out measurements on aluminum alloy (AA 6061) samples. Numerical simulations using the Finite Element Method (FEM) are also conducted to further demonstrate the potential of the proposed technique to detect localized damage in structural components. Second, the aforementioned nonlinear mixing technique is adapted to develop an NDE technique for characterizing thermal aging of adhesive joints. To this end, a nonlinear spring model is used to simulate the effect of the adhesive layer. Based on this nonlinear spring model, analytical expressions of the resonant wave generated by the adhesive layers is obtained through an asymptotic analysis when the adhesive layer thickness is much smaller than the pertinent wavelength. The solutions are expressed in terms of the properties of the adhesive layer. The nonlinear spring model shows a good agreement with the finite layer model solutions in the limit of a small thickness to wavelength ratio. Third, to demonstrate the effectiveness of this newly developed technique, measurements are conducted on adhesive joint samples made of two aluminum adherends bonded together by a polymer adhesive tape. The samples are aged in a thermal chamber to induce thermal ageing degradation in the adhesive layer. Using the developed wave-mixing technique in conjunction with the nonlinear spring model, we show that the thermal aging damage of the adhesive layer can be quantified from only one side of the sample. Finally, by mixing two L-waves, we develop a mixing technique to nondestructively evaluate the damage induced by alkali-silica reaction (ASR) in concrete. Experimental measurements are conducted on concrete prism samples that contain reactive aggregates and have been subjected to different ASR conditioning. This new technique takes into consideration of the significant attenuation caused by ASR-induced microcracks and scattering by the aggregates. The measurement results show that the ANLP has a much greater sensitivity to ASR damage than other parameters such as attenuation and wave speed. More remarkably, it is also found that the measured acoustic nonlinearity parameter is well-correlated with the reduction of the compressive strength induced by ASR damage. Thus, ANLP can be used to nondestructively track ASR damage in concrete.

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.

Ultrasonic Attenuation Results of Thermoplastic Resin Composites Undergoing Thermal and Fatigue Loading

NASA Technical Reports Server (NTRS)

Madaras, Eric I.

1998-01-01

As part of an effort to obtain the required information about new composites for aviation use, materials and NDE researchers at NASA are jointly performing mechanical and NDE measurements on new composite materials. The materials testing laboratory at NASA is equipped with environmental chambers mounted on load frames that can expose composite materials to thermal and loading cycles representative of flight protocols. Applying both temperature and load simultaneously will help to highlight temperature and load interactions during the aging of these composite materials. This report highlights our initial ultrasonic attenuation results from thermoplastic composite samples that have undergone over 4000 flight cycles to date. Ultrasonic attenuation measurements are a standard method used to assess the effects of material degradation. Recently, researchers have shown that they could obtain adequate contrast in the evaluation of thermal degradation in thermoplastic composites by using frequencies of ultrasound on the order of 24 MHz. In this study, we address the relationship of attenuation measured at lower frequencies in thermoplastic composites undergoing both thermal and mechanical loading. We also compare these thermoplastic results with some data from thermoset composites undergoing similar protocols. The composite s attenuation is reported as the slope of attenuation with respect to frequency, defined as b = Da(f)/Df. The slope of attenuation is an attractive parameter since it is quantitative, yet does not require interface corrections like conventional quantitative attenuation measurements. This latter feature is a consequence of the assumption that interface correction terms are frequency independent. Uncertainty in those correction terms can compromise the value of conventional quantitative attenuation data. Furthermore, the slope of the attenuation more directly utilizes the bandwidth information and in addition, the bandwidth can be adjusted in the post processing stage to compensate for the loss of dynamic range of the signal as the composites age.

Elemental analysis of silicon based minerals by ultrasonic slurry sampling electrothermal vaporisation ICP-MS.

PubMed

Rodríguez, Pablo Fernández; Marchante-Gayón, Juan Manuel; Sanz-Medel, Alfredo

2006-01-15

Ultrasonic slurry sampling electrothermal vaporisation inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) was applied to the elemental analysis of silicate based minerals, such as talc or quartz, without any pre-treatment except the grinding of the sample. The electrothermal vaporisation device consists of a tungsten coil connected to a home-made power supply. The voltage program, carrier gas flow rate and sonication time were optimised in order to obtain the best sensitivity for elements determined. The relationship between the amount of sample in the slurry and the signal intensity was also evaluated. Unfortunately, in all cases, quantification had to be carried out by the standard additions method owing to the strong matrix interferences. The global precision of the proposed method was always better than 12%. The limits of detection, calculated as three times the standard deviation of the blank value divided by the slope of the calibration curve, were between 0.5 ng/g for As and 3.5 ng/g for Ba. The method was validated by comparing the concentrations found for Cu, Mn, Cr, V, Li, Pb, Sn, Mg, U, Ba, Sr, Zn, Sb, Rb and Ce using the proposed methodology with those obtained by conventional nebulisation ICP-MS after acid digestion of the samples in a microwave oven. The concentration range in the solid samples was between 0.2 microg/g for Cr and 60 microg/g for Ba. All results were statistically in agreement with those found by conventional nebulisation.

Degradation studies of transparent conductive electrodes on electroactive poly(vinylidene fluoride) for uric acid measurements

NASA Astrophysics Data System (ADS)

Cardoso, Vanessa F.; Martins, Pedro; Botelho, Gabriela; Rebouta, Luis; Lanceros-Méndez, Senentxu; Minas, Graca

2010-08-01

Biochemical analysis of physiological fluids using, for example, lab-on-a-chip devices requires accurate mixing of two or more fluids. This mixing can be assisted by acoustic microagitation using a piezoelectric material, such as the β-phase of poly(vinylidene fluoride) (β-PVDF). If the analysis is performed using optical absorption spectroscopy and β-PVDF is located in the optical path, the material and its conductive electrodes must be transparent. Moreover, if, to improve the transmission of the ultrasonic waves to the fluids, the piezoelectric transducer is placed inside the fluidic structures, its degradation must be assessed. In this paper, we report on the degradation properties of transparent conductive oxides, namely, indium tin oxide (ITO) and aluminum-doped zinc oxide, when they are used as electrodes for providing acoustic microagitation. The latter promotes mixing of chemicals involved in the measurement of uric acid concentration in physiological fluids. The results are compared with those for aluminum electrodes. We find that β-PVDF samples with ITO electrodes do not degrade either with or without acoustic microagitation.

Endodontic Microsurgical Treatment of a Three-rooted Mandibular First Molar with Separate Distolingual Root: Report of One Case.

PubMed

Wang, Han Guo; Xu, Ning; Yu, Qing

The separate distolingual (DL) roots of three-rooted mandibular first molars are thought to be too difficult for performing apical surgery. This article represents microsurgical treatment of a three-rooted mandibular first molar with a separate DL root. The procedure includes incision and flap retraction, osteotomy, apicoectomy, retropreparation and retrofilling of the root canal, using micro instruments, ultrasonic retrotips and mineral trioxide aggregate (MTA) under a dental operating microscope. Two mm in length of apical root resection, 2 mm in depth of root canal retropreparation with a personalised ultrasonic retrotip, and 2 mm in length of retrofilling with MTA are the key points for accomplishment of apical surgery on separate DL roots. The case was followed up for 15 months after surgery. Clinical and radiographic examinations revealed complete healing of periapical tissue. Separate DL roots of three-rooted mandibular first molars can be treated by endodontic microsurgery with modifications from standard protocol.

ACID-BASE ACCOUNT EFFECTIVENESS FOR DETERMINATION OF MINE WASTE POTENTIAL ACIDITY. (R825549C048)

EPA Science Inventory

The oxidation of sulfide minerals in mine waste is a widespread source of resource degradation, often resulting in the generation of acidic water and mobilization of heavy metals. The quantity of acid forming minerals present in mine waste, dominantly as pyrite (FeS₂

Effects of yeast and bran on phytate degradation and minerals in rice bread.

PubMed

Kadan, R S; Phillippy, B Q

2007-05-01

Rice bread is a potential alternative to wheat bread for gluten-sensitive individuals. Incorporation of rice bran into bread made from white rice flour adds flavor but also phytic acid, which can reduce the bioavailability of minerals. Breads with varied amounts of defatted bran and yeast were prepared to determine their effects on the phytate and mineral contents of the bread. A completely randomized factorial design was used with bran levels of 3.7%, 7.3%, and 10.5% of the dry ingredients and yeast levels of 1.6%, 3.2%, and 4.7%. Increasing the amount of bran decreased the phytate degradation from 42% at the lowest level of bran to 10% at the highest, and the amount of yeast had no significant effect. The bran contributed substantial amounts of magnesium, iron, and zinc. Breads with the lowest level of bran had phytate-to-zinc molar ratios between 5 and 10, which suggest medium zinc bioavailability. Rice bread is a tasty and nutritious food that is a good dietary source of minerals for people who cannot tolerate wheat bread.

An OFDM Receiver with Frequency Domain Diversity Combined Impulsive Noise Canceller for Underwater Network.

PubMed

Saotome, Rie; Hai, Tran Minh; Matsuda, Yasuto; Suzuki, Taisaku; Wada, Tomohisa

2015-01-01

In order to explore marine natural resources using remote robotic sensor or to enable rapid information exchange between ROV (remotely operated vehicles), AUV (autonomous underwater vehicle), divers, and ships, ultrasonic underwater communication systems are used. However, if the communication system is applied to rich living creature marine environment such as shallow sea, it suffers from generated Impulsive Noise so-called Shrimp Noise, which is randomly generated in time domain and seriously degrades communication performance in underwater acoustic network. With the purpose of supporting high performance underwater communication, a robust digital communication method for Impulsive Noise environments is necessary. In this paper, we propose OFDM ultrasonic communication system with diversity receiver. The main feature of the receiver is a newly proposed Frequency Domain Diversity Combined Impulsive Noise Canceller. The OFDM receiver utilizes 20-28 KHz ultrasonic channel and subcarrier spacing of 46.875 Hz (MODE3) and 93.750 Hz (MODE2) OFDM modulations. In addition, the paper shows Impulsive Noise distribution data measured at a fishing port in Okinawa and at a barge in Shizuoka prefectures and then proposed diversity OFDM transceivers architecture and experimental results are described. By the proposed Impulsive Noise Canceller, frame bit error rate has been decreased by 20-30%.

Development of acoustic model-based iterative reconstruction technique for thick-concrete imaging

NASA Astrophysics Data System (ADS)

Almansouri, Hani; Clayton, Dwight; Kisner, Roger; Polsky, Yarom; Bouman, Charles; Santos-Villalobos, Hector

2016-02-01

Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well's health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.1

Simulation of ultrasonic focus aberration and correction through human tissue.

PubMed

Tabei, Makoto; Mast, T Douglas; Waag, Robert C

2003-02-01

Ultrasonic focusing in two dimensions has been investigated by calculating the propagation of ultrasonic pulses through cross-sectional models of human abdominal wall and breast. Propagation calculations used a full-wave k-space method that accounts for spatial variations in density, sound speed, and frequency-dependent absorption and includes perfectly matched layer absorbing boundary conditions. To obtain a distorted receive wavefront, propagation from a point source through the tissue path was computed. Receive focusing used an angular spectrum method. Transmit focusing was accomplished by propagating a pressure wavefront from a virtual array through the tissue path. As well as uncompensated focusing, focusing that employed time-shift compensation and time-shift compensation after backpropagation was investigated in both transmit and receive and time reversal was investigated for transmit focusing in addition. The results indicate, consistent with measurements, that breast causes greater focus degradation than abdominal wall. The investigated compensation methods corrected the receive focus better than the transmit focus. Time-shift compensation after backpropagation improved the focus from that obtained using time-shift compensation alone but the improvement was less in transmit focusing than in receive focusing. Transmit focusing by time reversal resulted in lower sidelobes but larger mainlobes than the other investigated transmit focus compensation methods.

Material State Awareness for Composites Part I: Precursor Damage Analysis Using Ultrasonic Guided Coda Wave Interferometry (CWI).

PubMed

Patra, Subir; Banerjee, Sourav

2017-12-16

Detection of precursor damage followed by the quantification of the degraded material properties could lead to more accurate progressive failure models for composite materials. However, such information is not readily available. In composite materials, the precursor damages-for example matrix cracking, microcracks, voids, interlaminar pre-delamination crack joining matrix cracks, fiber micro-buckling, local fiber breakage, local debonding, etc.-are insensitive to the low-frequency ultrasonic guided-wave-based online nondestructive evaluation (NDE) or Structural Health Monitoring (SHM) (~100-~500 kHz) systems. Overcoming this barrier, in this article, an online ultrasonic technique is proposed using the coda part of the guided wave signal, which is often neglected. Although the first-arrival wave packets that contain the fundamental guided Lamb wave modes are unaltered, the coda wave packets however carry significant information about the precursor events with predictable phase shifts. The Taylor-series-based modified Coda Wave Interferometry (CWI) technique is proposed to quantify the stretch parameter to compensate the phase shifts in the coda wave as a result of precursor damage in composites. The CWI analysis was performed on five woven composite-fiber-reinforced-laminate specimens, and the precursor events were identified. Next, the precursor damage states were verified using high-frequency Scanning Acoustic Microscopy (SAM) and optical microscopy imaging.

Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes.

PubMed

Bottrel, Sue Ellen C; Amorim, Camila C; Leão, Mônica M D; Costa, Elizângela P; Lacerda, Igor A

2014-01-01

In this study, photocatalytic (photo-Fenton and H2O2/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H2O2). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H2O2]0 = 400 mg L(-1). The photo-Fenton process mineralized 70% of the ETU with [H2O2]0 = 800 mg L(-1) and [Fe(2+)] = 400 mg L(-1), and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H2O2 from 800 mg L(-1) to 1200 mg L(-1) did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H2O2 and photo-Fenton processes were determined to be 6.2 × 10(-4) mg L(-1) min(-1) and 7.7 × 10(-4) mg L(-1) min(-1), respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.

Origin and influence of coal mine drainage on streams of the United States

USGS Publications Warehouse

Powell, J.D.

1988-01-01

Degradation of water quality related to oxidation of iron disulfide minerals associated with coal is a naturally occurring process that has been observed since the late seventeenth century, many years before commencement of commercial coal mining in the United States. Disturbing coal strata during mining operations accelerates this natural deterioration of water quality by exposing greater surface areas of reactive minerals to the weathering effects of the atmosphere, hydrosphere, and biosphere. Degraded water quality in the temperate eastern half of the United States is readily detected because of the low mineralization of natural water. Maps are presented showing areas in the eastern United States where concentrations of chemical constituents in water affected by coal mining (pH, dissolved sulfate, total iron, total manganese) exceed background values and indicate effects of coal mining. Areas in the East most affected by mine drainage are in western Pennsylvania, southern Ohio, western Maryland, West Virginia, southern Illinois, western Kentucky, northern Missouri, and southern Iowa. Effects of coal mining on water quality in the more arid western half of the United States are more difficult to detect because of the high degree of mineralization of natural water. Normal background concentrations of constituents are not useful in evaluating effects of coal mine drainage on streams in the more arid West. Three approaches to reduce the effects of coal mining on water quality are: (1) exclusion of oxygenated water from reactive minerals, (2) neutralization of the acid produced, (3) retardation of acid-producing bacteria population in spoil material, by application of detergents that do not produce byproducts requiring disposal. These approaches can be used to help prevent further degradation of water quality in streams by future mining. ?? 1988 Springer-Verlag New York Inc.

Electrochemical advanced oxidation for cold incineration of the pharmaceutical ranitidine: mineralization pathway and toxicity evolution.

PubMed

Olvera-Vargas, Hugo; Oturan, Nihal; Brillas, Enric; Buisson, Didier; Esposito, Giovanni; Oturan, Mehmet A

2014-12-01

Ranitidine (RNTD) is a widely prescribed histamine H2-receptor antagonist whose unambiguous presence in water sources appointed it as an emerging pollutant. Here, the degradation of 0.1 mM of this drug in aqueous medium was studied by electrochemical advanced oxidation processes (EAOPs) like anodic oxidation with electrogenerated H2O2 and electro-Fenton using Pt/carbon-felt, BDD/carbon-felt and DSA-Ti/RuO2–IrO2/carbon-felt cells. The higher oxidation power of the electro-Fenton process using a BDD anode was demonstrated. The oxidative degradation of RNTD by the electrochemically generated OH radicals obeyed a pseudo-first order kinetics. The absolute rate constant for its hydroxylation reaction was 3.39 × 109 M−1 s−1 as determined by the competition kinetics method. Almost complete mineralization of the RNTN solution was reached by using a BDD anode in both anodic oxidation with electrogenerated H2O2 and electro-Fenton processes. Up to 11 cyclic intermediates with furan moiety were detected from the degradation of RNTD, which were afterwards oxidized to short-chain carboxylic acids before their mineralization to CO2 and inorganic ions such as NH4+, NO3− and SO42−. Based on identified products, a plausible reaction pathway was proposed for RNTD mineralization. Toxicity assessment by the Microtox® method revealed that some cyclic intermediates are more toxic than the parent molecule. Toxicity was quickly removed following the almost total mineralization of the treated solution. Overall results confirm the effectiveness of EAOPs for the efficient removal of RNTD and its oxidation by-products from water.

Microbial mineralization of dichloroethene and vinyl chloride under hypoxic conditions

USGS Publications Warehouse

Bradley, Paul M.; Chapelle, Francis H.

2011-01-01

Mineralization of 14C-radiolabled vinyl chloride ([1,2-14C] VC) and cis-dichloroethene ([1,2-14C] cis-DCE) under hypoxic (initial dissolved oxygen (DO) concentrations about 0.1 mg/L) and nominally anoxic (DO minimum detection limit = 0.01 mg/L) was examined in chloroethene-exposed sediments from two groundwater and two surface water sites. The results show significant VC and dichloroethene (DCE) mineralization under hypoxic conditions. All the sample treatments exhibited pseudo-first-order kinetics for DCE and VC mineralization over an extended range of substrate concentrations. First-order rates for VC mineralization were approximately 1 to 2 orders of magnitude higher in hypoxic groundwater sediment treatments and at least three times higher in hypoxic surface water sediment treatments than in the respective anoxic treatments. For VC, oxygen-linked processes accounted for 65 to 85% of mineralization at DO concentrations below 0.1 mg/L, and 14CO2 was the only degradation product observed in VC treatments under hypoxic conditions. Because the lower detection limit for DO concentrations measured in the field is typically 0.1 to 0.5 mg/L, these results indicate that oxygen-linked VC and DCE biodegradation can be significant under field conditions that appear anoxic. Furthermore, because rates of VC mineralization exceeded rates of DCE mineralization under hypoxic conditions, DCE accumulation without concomitant accumulation of VC may not be evidence of a DCE degradative “stall” in chloroethene plumes. Significantly, mineralization of VC above the level that could reasonably be attributed to residual DO contamination was also observed in several nominally anoxic (DO minimum detection limit = 0.01 mg/L) microcosm treatments.

Influence of iron redox cycling on organo-mineral associations in arctic tundra soils

NASA Astrophysics Data System (ADS)

Herndon, E.; AlBashaireh, A.; Duroe, K.; Singer, D. M.

2016-12-01

Geochemical interactions between soil organic matter and minerals influence decomposition in many environments but remain poorly understood in arctic tundra systems. In tundra soils that are periodically to persistently saturated, the accumulation of iron oxyhydroxides and organo-iron precipitates at redox interfaces may inhibit decomposition by binding organic molecules and protecting them from microbial degradation. Here, we couple synchrotron-source spectroscopic techniques with chemical sequential extractions and physical density fractionations to evaluate the spatial distribution and speciation of Fe-bearing phases and associated organic matter in organic and mineral horizons of the seasonally thawed active layer in tundra soils from northern Alaska. Mineral-associated organic matter comprised 63 ± 9% of soil organic carbon stored in the active layer of ice wedge polygons. Ferrous iron produced in anoxic mineral horizons diffused upwards and precipitated as poorly-crystalline oxyhydroxides and organic-bound Fe(III) in the organic horizons. Ferrihydrite and goethite were present as coatings on mineral grains and plant debris and in aggregates with clays and particulate organic matter. Organic matter released through acid-dissolution of iron oxides may represent a small pool of readily-degradable organic molecules temporarily stabilized by sorption to iron oxyhydroxide surfaces, while larger quantities of particulate organic carbon and humic-like substances may be physically protected from decomposition by Fe-oxide coatings and aggregation. We conclude that formation of poorly-crystalline and crystalline iron oxides at redox interfaces contributes to mineral protection of organic matter through sorption, aggregation, and co-precipitation reactions. Further study of organo-mineral associations is necessary to determine the net impact of mineral-stabilization on carbon storage in rapidly warming arctic ecosystems.

Fabrication of TiO2/MoS2@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

NASA Astrophysics Data System (ADS)

Zhang, Weiping; Xiao, Xinyan; Zheng, Lili; Wan, Caixia

2015-12-01

TiO2/MoS2@zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl4 as Ti source, MoS2 as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM-EDS, TEM, XPS, UV-vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO2/MoS2@zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir-Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (kapp) (2.304 h-1) is higher than that of Degussa P25 (0.768 h-1); (3) the heterostructure consisted of zeolite, MoS2 and TiO2 nanostructure could provide synergistic effect for degradation of MO due to the efficient electron transfer process and better absorption property of TiO2/MoS2@zeolite composite photocatalyst.

Developing Effective Continuous On-Line Monitoring Technologies to Manage Service Degradation of Nuclear Power Plants

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

Meyer, Ryan M.; Ramuhalli, Pradeep; Bond, Leonard J.

2011-09-30

Recently, there has been increased interest in using prognostics (i.e, remaining useful life (RUL) prediction) for managing and mitigating aging effects in service-degraded passive nuclear power reactor components. A vital part of this philosophy is the development of tools for detecting and monitoring service-induced degradation. Experience with in-service degradation has shown that rapidly-growing cracks, including several varieties of stress corrosion cracks (SCCs), can grow through a pipe in less than one fuel outage cycle after they initiate. Periodic inspection has limited effectiveness at detecting and managing such degradation requiring a more versatile monitoring philosophy. Acoustic emission testing (AET) and guidedmore » wave ultrasonic testing (GUT) are related technologies with potential for on-line monitoring applications. However, harsh operating conditions within NPPs inhibit the widespread implementation of both technologies. For AET, another hurdle is the attenuation of passive degradation signals as they travel though large components, relegating AET to targeted applications. GUT is further hindered by the complexity of GUT signatures limiting its application to the inspection of simple components. The development of sensors that are robust and inexpensive is key to expanding the use of AET and GUT for degradation monitoring in NPPs and improving overall effectiveness. Meanwhile, the effectiveness of AET and GUT in NPPs can be enhanced through thoughtful application of tandem AET-GUT techniques.« less

Sealing ability of three root-end filling materials prepared using an erbium: Yttrium aluminium garnet laser and endosonic tip evaluated by confocal laser scanning microscopy

PubMed Central

Nanjappa, A Salin; Ponnappa, KC; Nanjamma, KK; Ponappa, MC; Girish, Sabari; Nitin, Anita

2015-01-01

Aims: (1) To compare the sealing ability of mineral trioxide aggregate (MTA), Biodentine, and Chitra-calcium phosphate cement (CPC) when used as root-end filling, evaluated under confocal laser scanning microscope using Rhodamine B dye. (2) To evaluate effect of ultrasonic retroprep tip and an erbium:yttrium aluminium garnet (Er:YAG) laser on the integrity of three different root-end filling materials. Materials and Methods: The root canals of 80 extracted teeth were instrumented and obturated with gutta-percha. The apical 3 mm of each tooth was resected and 3 mm root-end preparation was made using ultrasonic tip (n = 30) and Er:YAG laser (n = 30). MTA, Biodentine, and Chitra-CPC were used to restore 10 teeth each. The samples were coated with varnish and after drying, they were immersed in Rhodamine B dye for 24 h. The teeth were then rinsed, sectioned longitudinally, and observed under confocal laser scanning microscope. Statistical Analysis Used: Data were analyzed using one-way analysis of variance (ANOVA) and a post-hoc Tukey's test at P < 0.05 (R software version 3.1.0). Results: Comparison of microleakage showed maximum peak value of 0.45 mm for Biodentine, 0.85 mm for MTA, and 1.05 mm for Chitra-CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er:YAG laser when compared with ultrasonics, the difference was found to be statistically significant (P < 0.05). Conclusions: Root-end cavities prepared with Er:YAG laser and restored with Biodentine showed superior sealing ability compared to those prepared with ultrasonics. PMID:26180420

Lignin Degradation and Modification by the Soil-Inhabiting Fungus Fusarium proliferatum

PubMed Central

Regalado, V.; Rodriguez, A.; Perestelo, F.; Carnicero, A.; De La Fuente, G.; Falcon, M. A.

1997-01-01

A soil-inhabiting Fusarium proliferatum strain was capable of transforming or degrading nonlabeled and (sup14)C-labeled industrial, natural, and synthetic lignin. The mineralization rate per day (expressed as the percentage of added radioactivity recovered as to (sup14)CO(inf2)) was maximal during primary metabolism. PMID:16535700

Inhalation toxicology. III., Evaluation of thermal degradation products from aircraft and automobile engine oils, aircraft hydraulic fluid, and mineral oil.

DOT National Transportation Integrated Search

1983-04-01

A malfunctioning seal in the gear-reduction box of a turboprop aircraft engine could allow oil to enter the turbine's compressor section, which is the source of bleed air used to pressurize the cabin. Oil, or its degradation products, could have a de...

A new look at the multi-G model for organic carbon degradation in surface marine sediments for coupled benthic-pelagic simulations of the global ocean

NASA Astrophysics Data System (ADS)

Stolpovsky, Konstantin; Dale, Andrew W.; Wallmann, Klaus

2018-06-01

The kinetics of particulate organic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in global biogeochemical or Earth system circulation models to simulate climate-ocean interactions and biogeochemical tracer distributions in the ocean. In an attempt to improve our understanding of the rate and depth distribution of organic carbon mineralization in bioturbated (0-20 cm) sediments at the global scale, we parameterized a 1-D diagenetic model that simulates the mineralization of three discrete POC pools (a multi-G model). The rate constants of the three reactive classes (highly reactive, reactive, refractory) are fixed and determined to be 70, 0.5 and ˜ 0.001 yr-1, respectively, based on the Martin curve model for pelagic POC degradation. In contrast to previous approaches, however, the reactivity of the organic material degraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinking through the water column. Despite the simplifications of describing POC remineralization using G-type approaches, the model is able to simulate a global database (185 stations) of benthic oxygen and nitrate fluxes across the sediment-water interface in addition to porewater oxygen and nitrate distributions and organic carbon burial efficiencies. It is further consistent with degradation experiments using fresh phytoplankton reported in a previous study. We propose that an important yet mostly overlooked consideration in upscaling approaches is the proportion of the reactive POC classes reaching the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC degradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.

Anaerobic Degradation of Benzene, Toluene, Ethylbenzene, and Xylene Compounds by Dechloromonas Strain RCB

PubMed Central

Chakraborty, Romy; O'Connor, Susan M.; Chan, Emily; Coates, John D.

2005-01-01

Dechloromonas strain RCB has been shown to be capable of anaerobic degradation of benzene coupled to nitrate reduction. As a continuation of these studies, the metabolic versatility and hydrocarbon biodegradative capability of this organism were investigated. The results of these revealed that in addition to nitrate, strain RCB could alternatively degrade benzene both aerobically and anaerobically with perchlorate or chlorate [(per)chlorate] as a suitable electron acceptor. Furthermore, with nitrate as the electron acceptor, strain RCB could also utilize toluene, ethylbenzene, and all three isomers of xylene (ortho-, meta-, and para-) as electron donors. While toluene and ethylbenzene were completely mineralized to CO2, strain RCB did not completely mineralize para-xylene but rather transformed it to some as-yet-unidentified metabolite. Interestingly, with nitrate as the electron acceptor, strain RCB degraded benzene and toluene concurrently when the hydrocarbons were added as a mixture and almost 92 μM total hydrocarbons were oxidized within 15 days. The results of these studies emphasize the unique metabolic versatility of this organism, highlighting its potential applicability to bioremediative technologies. PMID:16332859

Recovery of Areas Degraded by Mining Within the Amazon Forest: Interaction of the Physical Condition of Soil and Biological Activity

NASA Astrophysics Data System (ADS)

Ribeiro, A. I.; Mello, G. F.; Longo, R. M.; Fengler, F. H.; Peche Filho, A., Sr.

2017-12-01

One of the greatest natural riches of Brazil is the Amazon rainforest. The Amazon region is known for its abundance of mineral resources, and may include topaz, oil, and especially cassiterite. In this scope, the mining sector in Brazil has great strategic importance because it accounts for approximately 30% of the country's exports with a mineral production of 40 billion dollars (Brazilian Mining Institute, 2015). In this scenario, as a consequence of mining, the Amazonian ecosystem has been undergoing a constant process of degradation. An important artifice in the exploitation of mineral resources is the rehabilitation and/or recovery of degraded areas. This recovery requires the establishment of degradation indicators and also the quality of the soil associated with its biota, since the Amazonian environment is dynamic, heterogeneous and complex in its physical, chemical and biological characteristics. In this way, this work presupposes that it is possible to characterize the different stages of recovery of tillage floor areas in deactivated cassiterite mines, within the Amazonian forest, in order to evaluate the interactions between the level of biological activity (Serrapilheira Height, Coefficient Metabolic, Basal Breath) and physical soil characteristics (aggregate DMG, Porosity, Total Soil Density, Moisture Content), through canonical correlation analysis. The results present correlations between the groups of indicators. Thus, from the use of the groups defined by canonical correlations, it was possible to identify the response of the set of physical and biological variables to the areas at different stages of recovery.

The Optical, Chemical, and Molecular Dissolved Organic Matter Succession Along a Boreal Soil-Stream-River Continuum

NASA Astrophysics Data System (ADS)

Hutchins, Ryan H. S.; Aukes, Pieter; Schiff, Sherry L.; Dittmar, Thorsten; Prairie, Yves T.; del Giorgio, Paul A.

2017-11-01

Soils export large amounts of organic matter to rivers, and there are still major uncertainties concerning the composition and reactivity of this material and its fate within the fluvial network. Here we reconstructed the pattern of movement and processing of dissolved organic matter (DOM) along a soil-stream-river continuum under summer baseflow conditions in a boreal region of Québec (Canada), using a combination of fluorescence spectra, size exclusion chromatography and ultrahigh resolution mass spectrometry. Our results show that there is a clear sequence of selective DOM degradation along the soil-stream-river continuum, which results in pronounced compositional shifts downstream. The soil-stream interface was a hot spot of DOM degradation, where biopolymers and low molecular weight (LMW) compounds were selectively removed. In contrast, processing in the stream channel was dominated by the degradation of humic-like aromatic DOM, likely driven by photolysis, with little further degradation of either biopolymers or LMW compounds. Overall, there was a high degree of coherence between the patterns observed in DOM chemical composition, optical properties, and molecular profiles, and none of these approaches pointed to measurable production of new DOM components, suggesting that the DOM pools removed during transit were likely mineralized to CO2. Our first order estimates suggest that rates of soil-derived DOM mineralization could potentially sustain over half of the measured CO2 emissions from this stream network, with mineralization of biopolymers and humic substances contributing roughly equally to these fluvial emissions.

Aerobic mineralization of MTBE and tert-butyl alcohol by stream-bed sediment microorganisms

USGS Publications Warehouse

Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

1999-01-01

Microorganisms indigenous to the stream-bed sediments at two gasoline- contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.Microorganisms indigenous to the stream-bed sediments at two gasoline-contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.

A Fracture Mechanics Approach to Thermal Shock Investigation in Alumina-Based Refractory

NASA Astrophysics Data System (ADS)

Volkov-Husović, T.; Heinemann, R. Jančić; Mitraković, D.

2008-02-01

The thermal shock behavior of large grain size, alumina-based refractories was investigated experimentally using a standard water quench test. A mathematical model was employed to simulate the thermal stability behavior. Behavior of the samples under repeated thermal shock was monitored using ultrasonic measurements of dynamic Young's modulus. Image analysis was used to observe the extent of surface degradation. Analysis of the obtained results for the behavior of large grain size samples under conditions of rapid temperature changes is given.

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.

Degradation of fluorobenzene and its central metabolites 3-fluorocatechol and 2-fluoromuconate by Burkholderia fungorum FLU100.

PubMed

Strunk, Niko; Engesser, Karl-Heinrich

2013-06-01

A halobenzene-degrading bacterium, Burkholderia fungorum FLU100 (DSM 23736), was isolated due to its outstanding trait to degrade fluorobenzene. Besides fluorobenzene, it utilizes, even in random mixtures, chlorobenzene, bromobenzene, iodobenzene, benzene, and toluene as sole sources of carbon and energy. FLU100 mineralizes mono-halogenated benzenes almost stoichiometrically (according to halide balance); after a lag phase, it also degrades 3-fluorophenol and 3-chlorophenol completely. The FLU100-derived transposon Tn5-mutant FLU100-P14R22 revealed 3-halocatechol to be a central metabolite of this new halobenzene degradation pathway. In FLU100, halocatechols are-as expected-strictly subject to ortho-cleavage of the catechol ring, with meta-cleavage never been observed. The strain is able to completely mineralize 3-fluorocatechol, the principal catecholic metabolite being nearly exclusively formed from fluorobenzene. The temporarily excreted 2-fluoromuconate formed thereof in turn is subsequently metabolized completely. This important finding falsifies the customary opinion of the persistence of 2-fluoromuconate valid up to now. The degradation of 4-fluorocatechol, however, being a very minor intermediate in FLU100, is substantially slower and incomplete and leads to the accumulation of uncharacterized derivatives of muconic acid and muconolactone in the medium. This branch therefore does not seem to be productive. To our knowledge, this represents the first example of the complete metabolism of 3-fluorocatechol via 2-fluoromuconate, a metabolite hitherto described as a dead-end metabolite in fluoroaromatic degradation.

Aging-associated modifications of collagen affect its degradation by matrix metalloproteinases.

PubMed

Panwar, Preety; Butler, Georgina S; Jamroz, Andrew; Azizi, Pouya; Overall, Christopher M; Brömme, Dieter

2018-01-01

The natural aging process and various pathologies correlate with alterations in the composition and the structural and mechanical integrity of the connective tissue. Collagens represent the most abundant matrix proteins and provide for the overall stiffness and resilience of tissues. The structural changes of collagens and their susceptibility to degradation are associated with skin wrinkling, bone and cartilage deterioration, as well as cardiovascular and respiratory malfunctions. Here, matrix metalloproteinases (MMPs) are major contributors to tissue remodeling and collagen degradation. During aging, collagens are modified by mineralization, accumulation of advanced glycation end-products (AGEs), and the depletion of glycosaminoglycans (GAGs), which affect fiber stability and their susceptibility to MMP-mediated degradation. We found a reduced collagenolysis in mineralized and AGE-modified collagen fibers when compared to native fibrillar collagen. GAGs had no effect on MMP-mediated degradation of collagen. In general, MMP digestion led to a reduction in the mechanical strength of native and modified collagen fibers. Successive fiber degradation with MMPs and the cysteine-dependent collagenase, cathepsin K (CatK), resulted in their complete degradation. In contrast, MMP-generated fragments were not or only poorly cleaved by non-collagenolytic cathepsins such as cathepsin V (CatV). In conclusion, our data indicate that aging and disease-associated collagen modifications reduce tissue remodeling by MMPs and decrease the structural and mechanic integrity of collagen fibers, which both may exacerbate extracellular matrix pathology. Copyright © 2017 Elsevier B.V. All rights reserved.

Treatment of N-Nitrosodimethylamine (NDMA) in Groundwater Using a Fluidized Bed Bioreactor

DTIC Science & Technology

2014-01-01

by the propanotroph Rhodococcus ruber ENV425 in batch culture. Figure 1.3 Effect of propane on the mineralization of 14C-NDMA to 14CO2 by the...propanotroph Rhodococcus ruber ENV425. Figure 1.4 Percent mineralization of 14C-NDMA to 14CO2 in microcosms prepared with aquifer solids and... mineralization by ENV425 in WSTF water. Figure 5.3 NDMA degradation by ENV425 in WSTF water. Figure 5.4 Photograph of the laboratory-scale FBR

Inoculation of soil with an Isoproturon degrading microbial community reduced the pool of "real non-extractable" Isoproturon residues.

PubMed

Zhu, Xiaomin; Schroll, Reiner; Dörfler, Ulrike; Chen, Baoliang

2018-03-01

During pesticides degradation, biogenic non-extractable residues ("apparent NER") may not share the same environmental fate and risks with the "real NER" that are bound to soil matrix. It is not clear how microbial community (MC) inoculation for pesticides degradation would influence the NER composition. To investigate degradation efficiency of pesticides Isoproturon (IPU) and NER composition following MC inoculation, clay particles harboring MC that contains the IPU degrading strain, Sphingomonas sp., were inoculated into soil receiving 14 C-labeled IPU addition. Mineralization of IPU was greatly enhanced with MC inoculation that averagely 55.9% of the applied 14 C-IPU was consumed up into 14 CO 2 during 46 days soil incubation. Isoproturon degradation was more thorough with MC than that in the control: much less amount of metabolic products (4.6% of applied IPU) and NER (35.4%) formed in MC treatment, while the percentages were respectively 30.3% for metabolites and 49.8% for NER in the control. Composition of NER shifted with MC inoculation, that relatively larger amount of IPU was incorporated into the biogenic "apparent NER" in comparison with "real NER". Besides its well-recognized role on enhancing mineralization, MC inoculation with clay particles benefits soil pesticides remediation in term of reducing "real NER" formation, which has been previously underestimated. Copyright © 2017 Elsevier Inc. All rights reserved.

Photocatalytic degradation of molinate in aqueous solutions.

PubMed

Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I

2014-11-01

In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

Ultrasound effects on the degradation kinetics, structure, and antioxidant activity of sea cucumber fucoidan.

PubMed

Guo, Xin; Ye, Xingqian; Sun, Yujing; Wu, Dan; Wu, Nian; Hu, Yaqin; Chen, Shiguo

2014-02-05

The effects of ultrasound on the molecular weight, structure, and antioxidant potential of a fucoidan found in Isostichopus badionotus were investigated. The results showed the molecular weight (Mw) of fucoidan decreased obviously after ultrasound treatment. Higher ultrasonic intensity, lower temperature, and lower fucoidan concentrations led to a more effective sonochemical effect. The kinetic model for fucoidan degradation fitted to 1/M(wt)-1/M(w0) = kt at the tested temperature. The optimized degradation conditions by response surface methodology (RSM) were temperature, 12 °C, and intensity, 508 W/cm². Structural analysis by FTIR and NMR indicated the fucoidan kept the linear tetrasaccharide repeating units as the original polysaccharides after the ultrasound treatment, with only slight destruction of the middle nonsulfated fucose units. Antioxidant activity assay showed the antioxidant activity was slightly improved by the ultrasound treatment. The results suggested that ultrasound treatment is an effective approach to decrease the M(w) of fucoidan with only minor structural destruction.

Photo-, sono- and sonophotocatalytic degradation of methylene blue using Fe3O4/ZrO2 composites catalysts

NASA Astrophysics Data System (ADS)

Kristianto, Y.; Taufik, A.; Saleh, R.

2017-07-01

In the present work, magnetite material Fe3O4/ZrO2 with various molar ratios was prepared by the two-step method (sol-gel followed by the ultrasonic-assisted method). The as-prepared samples were fairly characterized by various characterization methods, such as X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM), Fourier Transform Infrared (FT-IR) and Thermal Gravimetric Analysis (TGA). The catalytic performance of the as-prepared samples was evaluated based on the degradation of methylene blue under UV light, ultrasound and combination of UV and ultrasound irradiation. The results revealed that the sample with Fe3O4:ZrO2 molar ratio of 0.5:1 showed the best catalytic performance under UV, ultrasound and UV + ultrasound irradiation. The degradation of methylene blue follows the order: sonophotocatalytic > sonocatalytic > photocatalytic. In addition, the effect of various scavengers has also been studied. Furthermore, all prepared samples could be used as a convenient recyclable catalyst.

Monitoring Microbial Mineralization Using Reverse Stable Isotope Labeling Analysis by Mid-Infrared Laser Spectroscopy

PubMed Central

2017-01-01

Assessing the biodegradation of organic compounds is a frequent question in environmental science. Here, we present a sensitive, inexpensive, and simple approach to monitor microbial mineralization using reverse stable isotope labeling analysis (RIL) of dissolved inorganic carbon (DIC). The medium for the biodegradation assay contains regular organic compounds and 13C-labeled DIC with 13C atom fractions (x(13C)DIC) higher than natural abundance (typically 2–50%). The produced CO2 (x(13C) ≈ 1.11%) gradually dilutes the initial x(13C)DIC allowing to quantify microbial mineralization using mass-balance calculations. For 13C-enriched CO2 samples, a newly developed isotope ratio mid-infrared spectrometer was introduced with a precision of x(13C) < 0.006%. As an example for extremely difficult and slowly degradable compounds, CO2 production was close to the theoretical stoichiometry for anaerobic naphthalene degradation by a sulfate-reducing enrichment culture. Furthermore, we could measure the aerobic degradation of dissolved organic carbon (DOC) adsorbed to granular activated carbon in a drinking water production plant, which cannot be labeled with 13C. Thus, the RIL approach can be applied to sensitively monitor biodegradation of various organic compounds under anoxic or oxic conditions. PMID:28903553

Photodegradation of decabromodiphenyl ether adsorbed onto clay minerals, metal oxides, and sediment.

PubMed

Ahn, Mi-Youn; Filley, Timothy R; Jafvert, Chad T; Nies, Loring; Hua, Inez; Bezares-Cruz, Juan

2006-01-01

The photodebromination of decabromodiphenyl ether (BDE-209) adsorbed onto six different solid matrixes was investigated in sunlight and by irradiation with 350 +/- 50 nm lamps (four lamps at 24 W each). After 14 days of lamp irradiation, BDE-209 degraded with a half-life of 36 and 44 days, respectively, on montmorillonite or kaolinite, with much slower degradation occurring when sorbed on organic carbon-rich natural sediment (t1/2 = 150 days). In late summer and fall sunlight (40.5 degrees N, elevation 600 ft), the half-lives of BDE-209 sorbed on montmorillonite and kaolinite were 261 and 408 days, respectively. Under both irradiation schemes, no significant loss of BDE-209 occurred when sorbed to aluminum hydroxide, iron oxide (ferrihydrite), or manganese dioxide (birnessite). Upon exposure to both lamp and solar light and in the presence of montmorillonite and kaolinite, numerous lesser brominated congeners (tri- to nonabromodiphenyl ethers) were produced. Nearly identical product distribution was evident on montmorillonite and kaolinite. Dark control experiments for each mineral showed no disappearance of BDE-209 or appearance of degradation products. These results suggest that photodegradation of BDE-209 on mineral aerosols during long-range atmospheric transport may be an important fate process for BDE-209 in the environment.

Improving degradation of paracetamol by integrating gamma radiation and Fenton processes.

PubMed

Cruz-González, Germán; Rivas-Ortiz, Iram B; González-Labrada, Katia; Rapado-Paneque, Manuel; Chávez-Ardanza, Armando; Nuevas-Paz, Lauro; Jáuregui-Haza, Ulises J

2016-10-14

Degradation of paracetamol (N-(4-hydroxiphenyl)acetamide) in aqueous solution by gamma radiation, gamma radiation/H2O2 and gamma radiation/Fenton processes was studied. Parameters affecting the radiolysis of paracetamol such as radiation dose, initial concentration of pollutant, pH and initial oxidant concentration were investigated. Gamma radiation was performed using a (60)Co source irradiator. Paracetamol degradation and mineralization increased with increasing absorbed radiation dose, but decreased with increasing initial concentration of the drug in aqueous solution. The addition of H2O2 resulted in an increased effect on irradiation-driven paracetamol degradation in comparison with the performance of the irradiation-driven process alone: paracetamol removal increased from 48.9% in the absence of H2O2 to 95.2% for H2O2 concentration of 41.7 mmol/L. However, the best results were obtained with gamma radiation/Fenton process with 100% of the drug removal at 5 kGy, for optimal H2O2 and Fe(2+) concentrations at 13.9 and 2.3 mmol/L, respectively, with a high mineralization of 63.7%. These results suggest gamma radiation/H2O2 and gamma radiation/Fenton processes as promising methods for paracetamol degradation in polluted wastewaters.

Community structure and PAH ring-hydroxylating dioxygenase genes of a marine pyrene-degrading microbial consortium.

PubMed

Gallego, Sara; Vila, Joaquim; Tauler, Margalida; Nieto, José María; Breugelmans, Philip; Springael, Dirk; Grifoll, Magdalena

2014-07-01

Marine microbial consortium UBF, enriched from a beach polluted by the Prestige oil spill and highly efficient in degrading this heavy fuel, was subcultured in pyrene minimal medium. The pyrene-degrading subpopulation (UBF-Py) mineralized 31 % of pyrene without accumulation of partially oxidized intermediates indicating the cooperation of different microbial components in substrate mineralization. The microbial community composition was characterized by culture dependent and PCR based methods (PCR-DGGE and clone libraries). Molecular analyses showed a highly stable community composed by Alphaproteobacteria (84 %, Breoghania, Thalassospira, Paracoccus, and Martelella) and Actinobacteria (16 %, Gordonia). The members of Thalasosspira and Gordonia were not recovered as pure cultures, but five additional strains, not detected in the molecular analysis, that classified within the genera Novosphingobium, Sphingopyxis, Aurantimonas (Alphaproteobacteria), Alcanivorax (Gammaproteobacteria) and Micrococcus (Actinobacteria), were isolated. None of the isolates degraded pyrene or other PAHs in pure culture. PCR amplification of Gram-positive and Gram-negative dioxygenase genes did not produce results with any of the cultured strains. However, sequences related to the NidA3 pyrene dioxygenase present in mycobacterial strains were detected in UBF-Py consortium, suggesting the representative of Gordonia as the key pyrene degrader, which is consistent with a preeminent role of actinobacteria in pyrene removal in coastal environments affected by marine oil spills.

Short-term effects of mineral particle sizes on cellular degradation activity after implantation of injectable calcium phosphate biomaterials and the consequences for bone substitution.

PubMed

Gauthier, O; Bouler, J M; Weiss, P; Bosco, J; Aguado, E; Daculsi, G

1999-08-01

This in vivo study investigated the influence of two calcium phosphate particle sizes (40-80 microm and 200-500 microm) on the cellular degradation activity associated with the bone substitution process of two injectable bone substitutes (IBS). The tested biomaterials were obtained by associating a biphasic calcium phosphate (BCP) ceramic mineral phase and a 3% aqueous solution of a cellulosic polymer (hydroxypropylmethylcellulose). Both were injected into osseous defects at the distal end of rabbit femurs for 2- and 3-week periods. Quantitative results for tartrate-resistant acid phosphatase (TRAP) cellular activity, new bone formation, and ceramic resorption were studied for statistical purposes. Positive TRAP-stained degradation cells were significantly more numerous for IBS 40-80 than IBS 200-500, regardless of implantation time. BCP degradation was quite marked during the first 2 weeks for IBS 40-80, and bone colonization occurred more extensively for IBS 40-80 than for IBS 200-500. The resorption-bone substitution process occurred earlier and faster for IBS 40-80 than IBS 200-500. Both tested IBS displayed similar biological efficiency, with conserved in vivo bioactivity and bone-filling ability. Differences in calcium phosphate particle sizes influenced cellular degradation activity and ceramic resorption but were compatible with efficient bone substitution.

A review of liquid lubricant thermal/oxidative degradation

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.

1983-01-01

The fundamental processes occurring during the thermal and oxidative degradation of hydrocarbons are reviewed. Particular emphasis is given to various classes of liquid lubricants such as mineral oils, esters, polyphenyl ethers, C-ethers, and fluorinated polyethers. Experimental techniques for determining thermal and oxidative stabilities of lubricants are discussed. The role of inhibitors and catalysis is also covered.

Quantifying the degradation of degradable implants and bone formation in the femoral condyle using micro-CT 3D reconstruction

PubMed Central

Xu, Yichi; Meng, Haoye; Yin, Heyong; Sun, Zhen; Peng, Jiang; Xu, Xiaolong; Guo, Quanyi; Xu, Wenjing; Yu, Xiaoming; Yuan, Zhiguo; Xiao, Bo; Wang, Cheng; Wang, Yu; Liu, Shuyun; Lu, Shibi; Wang, Zhaoxu; Wang, Aiyuan

2018-01-01

Degradation limits the application of magnesium alloys, and evaluation methods for non-traumatic in vivo quantification of implant degradation and bone formation are imperfect. In the present study, a micro-arc-oxidized AZ31 magnesium alloy was used to evaluate the degradation of implants and new bone formation in 60 male New Zealand white rabbits. Degradation was monitored by weighing the implants prior to and following implantation, and by performing micro-computed tomography (CT) scans and histological analysis after 1, 4, 12, 24, 36, and 48 weeks of implantation. The results indicated that the implants underwent slow degradation in the first 4 weeks, with negligible degradation in the first week, followed by significantly increased degradation during weeks 12–24 (P<0.05), and continued degradation until the end of the 48-week experimental period. The magnesium content decreased as the implant degraded (P<0.05); however, the density of the material exhibited almost no change. Micro-CT results also demonstrated that pin volume, pin mineral density, mean ‘pin thickness’, bone surface/bone volume and trabecular separation decreased over time (P<0.05), and that the pin surface area/pin volume, bone volume fraction, trabecular thickness, trabecular number and tissue mineral density increased over time (P<0.05), indicating that the number of bones and density of new bone increased as magnesium degraded. These results support the positive effect of magnesium on osteogenesis. However, from the maximum inner diameter of the new bone loop and diameter of the pin in the same position, the magnesium alloy was not capable of creating sufficient bridges between the bones and biomaterials when there were preexisting gaps. Histological analyses indicated that there were no inflammatory responses around the implants. The results of the present study indicate that a micro-arc-oxidized AZ31 magnesium alloy is safe in vivo and efficiently degraded. Furthermore, the novel bone formation increased as the implant degraded. The findings concluded that micro-CT, which is useful for providing non-traumatic, in vivo, quantitative and precise data, has great value for exploring the degradation of implants and novel bone formation. PMID:29375677

Quantifying the degradation of degradable implants and bone formation in the femoral condyle using micro-CT 3D reconstruction.

PubMed

Xu, Yichi; Meng, Haoye; Yin, Heyong; Sun, Zhen; Peng, Jiang; Xu, Xiaolong; Guo, Quanyi; Xu, Wenjing; Yu, Xiaoming; Yuan, Zhiguo; Xiao, Bo; Wang, Cheng; Wang, Yu; Liu, Shuyun; Lu, Shibi; Wang, Zhaoxu; Wang, Aiyuan

2018-01-01

Degradation limits the application of magnesium alloys, and evaluation methods for non-traumatic in vivo quantification of implant degradation and bone formation are imperfect. In the present study, a micro-arc-oxidized AZ31 magnesium alloy was used to evaluate the degradation of implants and new bone formation in 60 male New Zealand white rabbits. Degradation was monitored by weighing the implants prior to and following implantation, and by performing micro-computed tomography (CT) scans and histological analysis after 1, 4, 12, 24, 36, and 48 weeks of implantation. The results indicated that the implants underwent slow degradation in the first 4 weeks, with negligible degradation in the first week, followed by significantly increased degradation during weeks 12-24 (P<0.05), and continued degradation until the end of the 48-week experimental period. The magnesium content decreased as the implant degraded (P<0.05); however, the density of the material exhibited almost no change. Micro-CT results also demonstrated that pin volume, pin mineral density, mean 'pin thickness', bone surface/bone volume and trabecular separation decreased over time (P<0.05), and that the pin surface area/pin volume, bone volume fraction, trabecular thickness, trabecular number and tissue mineral density increased over time (P<0.05), indicating that the number of bones and density of new bone increased as magnesium degraded. These results support the positive effect of magnesium on osteogenesis. However, from the maximum inner diameter of the new bone loop and diameter of the pin in the same position, the magnesium alloy was not capable of creating sufficient bridges between the bones and biomaterials when there were preexisting gaps. Histological analyses indicated that there were no inflammatory responses around the implants. The results of the present study indicate that a micro-arc-oxidized AZ31 magnesium alloy is safe in vivo and efficiently degraded. Furthermore, the novel bone formation increased as the implant degraded. The findings concluded that micro-CT, which is useful for providing non-traumatic, in vivo , quantitative and precise data, has great value for exploring the degradation of implants and novel bone formation.

Sorption and stability of the polycyclic nitramine explosive CL-20 in soil.

PubMed

Balakrishnan, Vimal K; Monteil-Rivera, Fanny; Gautier, Mathieu A; Hawari, Jalal

2004-01-01

The polycyclic nitramine CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) is being considered for use as a munition, but its environmental fate and impact are unknown. The present study consisted of two main elements. First, sorption-desorption data were measured with soils and minerals to evaluate the respective contributions of organic matter and minerals to CL-20 immobilization. Second, since CL-20 hydrolyzes at a pH of >7, the effect of sorption on CL-20 degradation was examined in alkaline soils. Sorption-desorption isotherms measured using five slightly acidic soils (5.1 < pH < 6.9) containing various amounts of total organic carbon (TOC) revealed a nonlinear sorption that increased with TOC [K(d) (0.33% TOC) = 2.4 L kg(-1); K(d) (20% TOC) = 311 L kg(-1)]. Sorption to minerals (Fe(2)O(3), silica, kaolinite, montmorillonite, illite) was very low (0 < K(d) < 0.6 L kg(-1)), suggesting that mineral phases do not contribute significantly to CL-20 sorption. Degradation of CL-20 in sterile soils having different pH values increased as follows: sandy agricultural topsoil from Varennes, QC, Canada (VT) (pH = 5.6; K(d) = 15 L kg(-1); 8% loss) < clay soil from St. Sulpice, QC, Canada (CSS) (pH = 8.1; K(d) = 1 L kg(-1); 82% loss) < sandy soil provided by Agriculture Canada (SAC) (pH = 8.1, K(d) = approximately 0 L kg(-1); 100% loss). The faster degradation in SAC soil compared with CSS soil was attributed to the absence of sorption in the former. In summary, CL-20 is highly immobilized by soils rich in organic matter. Although sorption retards abiotic degradation, CL-20 still decomposes in soils where pH is >7.5, suggesting that it will not persist in even slightly alkaline soils.

Enhanced photocatalytic efficiency of NiS/TiO{sub 2} composite catalysts using sunset yellow, an azo dye under day light illumination

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

Rajamanickam, D.; Dhatshanamurthi, P.; Shanthi, M., E-mail: shanthimsm@gmail.com

2015-01-15

Highlights: • NiS/TiO{sub 2} was successfully synthesized by sol–gel method. • This new method of preparation gives a homogeneous dispersion of NiS on TiO{sub 2}. • Degradation activity of NiS/TiO{sub 2} is found to be more efficient than other catalysts. • Addition of oxidants enhances the degradation efficiency significantly. • COD measurements reveal the complete mineralization of dye molecules. • The catalyst is found to be reusable. - Abstract: To improve the solar light induced photocatalytic application performances of TiO{sub 2}, in this study, the NiS modified TiO{sub 2} composite photocatalysts with various ratios of NiS to TiO{sub 2} weremore » prepared by sol–gel method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM), energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (B–E–T) surface area measurement methods. The photocatalytic activity of NiS/TiO{sub 2} was investigated for the degradation of sunset yellow (SY) in aqueous solution using solar light. The NiS/TiO{sub 2} is found to be more efficient than prepared TiO{sub 2} and TiO{sub 2}–P25 at pH 7 for the mineralization of SY. The effects of operational parameters such as the amount of photocatalyst, dye concentration and initial pH on photo mineralization of SY have been analyzed. The degradation was strongly enhanced in the presence of oxidants such as H{sub 3}K{sub 5}O{sub 18}S{sub 4} (Oxone), KIO{sub 4}, and KBrO{sub 3}. The mineralization of SY has been identified by COD measurements. The catalyst is found to be reusable.« less

Impact of Inoculation Protocols, Salinity, and pH on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) and Survival of PAH-Degrading Bacteria Introduced into Soil

PubMed Central

Kästner, Matthias; Breuer-Jammali, Maren; Mahro, Bernd

1998-01-01

Degradation of polycyclic aromatic hydrocarbons (PAHs) and survival of bacteria in soil was investigated by applying different inoculation protocols. The soil was inoculated with Sphingomonas paucimobilis BA 2 and strain BP 9, which are able to degrade anthracene and pyrene, respectively. CFU of soil bacteria and of the introduced bacteria were monitored in native and sterilized soil at different pHs. Introduction with mineral medium inhibited PAH degradation by the autochthonous microflora and by the strains tested. After introduction with water (without increase of the pore water salinity), no inhibition of the autochthonous microflora was observed and both strains exhibited PAH degradation. PMID:9435090

Ultrasound-Assisted Synthesis of Titania Nanoparticles, Characterization of Their Thin Films, and Activity in Photooxidation of β-Naphthol

NASA Astrophysics Data System (ADS)

Hurain, Syyeda Sana; Habib, Amir; Hussain, Syed Muzammil; Ul-Haq, Noaman

2015-11-01

Nanosized titania (TiO2) films and powders were prepared from titanium isopropoxide by ultrasonication then ultrasonic aerosol-assisted chemical vapor deposition (UAACVD). X-ray diffraction (XRD), used to study the crystal structure, phase, and crystallite size of TiO2 samples annealed at 500°C, revealed anatase was the main crystalline phase. Scanning electron microscopy and atomic force microscopy revealed the quasi-spherical morphology of the TiO2 nanoparticles; average size distribution was in the range 20-35 nm. Ultraviolet-visible spectroscopy was used to evaluate the photocatalytic activity of the anatase TiO2, on the basis of efficiency of degradation of β-naphthol. Pure TiO2 nanoparticles synthesized by use of sonication-UAACVD then calcination at 500°C enabled effective photodegradation under UV light. This method of synthesis of TiO2 is superior to the reflux-UAACVD method with titanium isopropoxide as precursor.

A thermodynamic approach to nonlinear ultrasonics for material state awareness and prognosis

NASA Astrophysics Data System (ADS)

Chillara, Vamshi Krishna

2017-11-01

We develop a thermodynamic framework for modeling nonlinear ultrasonic damage sensing and prognosis in materials undergoing progressive damage. The framework is based on the internal variable approach and relies on the construction of a pseudo-elastic strain energy function that captures the energetics associated with the damage progression. The pseudo-elastic strain energy function is composed of two energy functions—one that describes how a material stores energy in an elastic fashion and the other describes how material dissipates energy or stores it in an inelastic fashion. Experimental motivation for the choice of the above two functionals is discussed and some specific choices pertaining to damage progression during fatigue and creep are presented. The thermodynamic framework is employed to model the nonlinear response of material undergoing stress relaxation and creep-like degradation. For each of the above cases, evolution of the nonlinearity parameter with damage as well as with macroscopic measurables like accumulated plastic strain is obtained.

Ultrasonic Guided-Wave Scan System Used to Characterize Microstructure and Defects in Ceramic Composites

NASA Technical Reports Server (NTRS)

Roth, Don J.; Cosgriff, Laura M.; Martin, Richard E.; Verrilli, Michael J.; Bhatt, Ramakrishna T.

2004-01-01

Ceramic matrix composites (CMCs) are being developed for advanced aerospace propulsion applications to save weight, improve reuse capability, and increase performance. However, mechanical and environmental loads applied to CMCs can cause discrete flaws and distributed microdamage, significantly reducing desirable physical properties. Such microdamage includes fiber/matrix debonding (interface failure), matrix microcracking, fiber fracture and buckling, oxidation, and second phase formation. A recent study (ref. 1) of the durability of a C/SiC CMC discussed the requirement for improved nondestructive evaluation (NDE) methods for monitoring degradation in these materials. Distributed microdamage in CMCs has proven difficult to characterize nondestructively because of the complex microstructure and macrostructure of these materials. This year, an ultrasonic guided-wave scan system developed at the NASA Glenn Research Center was used to characterize various microstructural and flaw conditions in SiC/SiC (silicon carbide fiber in silicon carbide matrix) and C/SiC (carbon fiber in silicon carbide matrix) CMC samples.

Ultrasonic seam welding on thin silicon solar cells

NASA Technical Reports Server (NTRS)

Stofel, E. J.

1982-01-01

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

Degradation of polycyclic aromatic hydrocarbons (PAHs) in textile dyeing sludge with ultrasound and Fenton processes: Effect of system parameters and synergistic effect study.

PubMed

Lin, Meiqing; Ning, Xun-an; An, Taicheng; Zhang, Jianhao; Chen, Changmin; Ke, Yaowei; Wang, Yujie; Zhang, Yaping; Sun, Jian; Liu, Jingyong

2016-04-15

To establish an efficient oxidation process for the degradation of polycyclic aromatic hydrocarbons (PAHs) in textile dyeing sludge, the effects of various operating parameters were optimized during the ultrasound process, Fenton process and the combined ultrasound-Fenton process. The results showed that the ultrasonic density of 1.80w/cm(3), both H2O2 and Fe(2+) dosages of 140mmol/L and pH 3 were favorable conditions for the degradation of PAHs. The degradation efficiency of high molecular weight PAHs was close to or even higher than that of light molecular weight PAHs. The highest degradation efficiencies of Σ16 PAHs were obtained within 30min in the order of: Fenton (83.5%) >ultrasound-Fenton (75.5%) >ultrasound (45.5%), then the efficiencies were decreased in the other of: ultrasound-Fenton (73.0%) >Fenton (70.3%) >ultrasound (41.4%) in 60min. The extra PAHs were released from the intracellular substances and the cavities of sludge due to the disruption of sludge during the oxidation process. Also, the degradation of PAHs could be inhibited by the other organic matter in the sludge. The combined ultrasound-Fenton process showed more efficient than both ultrasound process and Fenton process not only in the surface of sludge but also in the sludge interior. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic cobalt ferrite composite as an efficient catalyst for photocatalytic oxidation of carbamazepine.

PubMed

He, Yongzhen; Dai, Chaomeng; Zhou, Xuefei

2017-01-01

A magnetic spinel cobalt ferrite nanoparticle composite (CFO) was prepared via an ultrasonication-assisted co-precipitation method. The morphological structure and surface composition of CFO before and after reaction were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and Fourier transform infrared spectroscopy, indicating the consumption of iron oxide during photodegradation. X-ray photoelectron spectroscopy and vibrating sample magnetometry confirm the preparation of the ferrite nanoparticle composite and its magnetic properties. The prepared CFO was then used for the photocatalytic degradation of carbamazepine (CBZ) as an example of pharmaceuticals and personal care products (PPCPs) from aqueous solution. The effects of the nanocomposite dosage, contact time, and solution pH on the photodegradation process were investigated. More than 96% of the CBZ was degraded within 100 min at 0.2 g·L -1 CFO in the presence of UV light. The reactive species for CBZ degradation in the CFO/UV system was identified as hydroxyl radicals by the methanol scavenging method. Combined with the detection of leached iron ions during the process, the CBZ degradation mechanism can be presumed to be heterogeneous and homogeneous photocatalytic degradation in the CFO/UV system. Furthermore, iminostilbene and acridine were detected as intermediate products by GC-MS.

Multi-Source 3d Models Supporting Ultrasonic Test to Investigate AN Egyptian Sculpture of the Archaeological Museum in Bologna

NASA Astrophysics Data System (ADS)

Di Pietra, V.; Donadio, E.; Picchi, D.; Sambuelli, L.; Spanò, A.

2017-02-01

The paper presents the workflow and the results of an ultrasonic 3D investigation and a 3D survey application aimed at the assessment of the internal integrity of an ancient sculpture. The work aimed at highlighting the ability of methods devoted to the 3D geometry acquisition of small objects when applied to diagnosis performed by geophysical investigation. In particular, two methods widely applied for small objects modelling are considered and compared, the digital Photogrammetry with the Structure from Motion (SFM) technique and hand-held 3D scanners. The study concludes with the aim to enhance the final graphical representation of the tomographic results and to subject the obtained results to a quantitative analysis. The survey is applied to the Egyptian naophorous statue of Amenmes and Reshpu, which dates to the reign of Ramses II (1279-1213 BC) or later and is now preserved in the Civic Archaeological Museum in Bologna. In order to evaluate the internal persistency of fractures and visible damages, a 3D Ultrasonic Tomographic Imaging (UTI) test has been performed and a multi-sensor survey (image and range based) was conducted, in order to evaluate the locations of the source and receiver points as accurate as possible The presented test allowed to evaluate the material characteristics, its porosity and degradation state, which particularly affect the lower part of the statue. More in general, the project demonstrated how solution coming from the field of 3D modelling of Cultural Heritage allow the application of 3D ultrasonic tomography also on objects with complex shapes, in addition to the improved representation of the obtained results.

Ultrasound assisted enzymatic depolymerization of aqueous guar gum solution.

PubMed

Prajapat, Amrutlal L; Subhedar, Preeti B; Gogate, Parag R

2016-03-01

The present work investigates the effectiveness of application of low intensity ultrasonic irradiation for the intensification of enzymatic depolymerization of aqueous guar gum solution. The extent of depolymerization of guar gum has been analyzed in terms of intrinsic viscosity reduction. The effect of ultrasonic irradiation on the kinetic and thermodynamic parameters related to the enzyme activity as well as the intrinsic viscosity reduction of guar gum using enzymatic approach has been evaluated. The kinetic rate constant has been found to increase with an increase in the temperature and cellulase loading. It has been observed that application of ultrasound not only enhances the extent of depolymerization but also reduces the time of depolymerization as compared to conventional enzymatic degradation technique. In the presence of cellulase enzyme, the maximum extent of depolymerization of guar gum has been observed at 60 W of ultrasonic rated power and ultrasonic treatment time of 30 min. The effect of ultrasound on the kinetic and thermodynamic parameters as well as the molecular structure of cellulase enzyme was evaluated with the help of the chemical reaction kinetics model and fluorescence spectroscopy. Application of ultrasound resulted in a reduction in the thermodynamic parameters of activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) by 47%, 50%, 65% and 1.97%, respectively. The changes in the chemical structure of guar gum treated using ultrasound assisted enzymatic approach in comparison to the native guar gum were also characterized by FTIR. The results revealed that enzymatic depolymerization of guar gum resulted in a polysaccharide with low degree of polymerization, viscosity and consistency index without any change in the core chemical structure which could make it useful for incorporation in food products. Copyright © 2015 Elsevier B.V. All rights reserved.

New insight into the mechanism of peroxymonosulfate activation by sulfur-containing minerals: Role of sulfur conversion in sulfate radical generation.

PubMed

Zhou, Yang; Wang, Xiaolei; Zhu, Changyin; Dionysiou, Dionysios D; Zhao, Guangchao; Fang, Guodong; Zhou, Dongmei

2018-06-04

Peroxymonosulfate (PMS) or persulfate activation by sulfur-containing minerals has been applied extensively for the degradation of contaminants; however, the role of sulfur conversion in this process has not been fully explored. In this study, pyrite (FeS 2 )-based PMS activation process was developed for diethyl phthalate (DEP) degradation, and its underlying mechanisms were elucidated. PMS was found to be efficiently activated by FeS 2 for DEP degradation and mineralization, achieving 58.9% total organic carbon removal using 0.5 g/L FeS 2 and 2.0 mM PMS. Sulfides were the dominant electron donor for PMS activation, and mediated Fe(II) regeneration to activate PMS on the surface of FeS 2 particles. Meanwhile, different sulfur conversion intermediates, such as S 5 2- , S 8 0 , S 2 O 3 2- , and SO 3 2- , were formed from the oxidation of sulfides by Fe(III) and PMS, and determined by X-ray photoelectron spectroscopy and in-situ attenuated total reflectance Fourier transform infrared spectroscopy analysis. SO 3 2- was the dominant sulfur species responsible for sulfate radicals (SO 4 - ) generation by activating PMS directly or activating Fe(III) to initiate a radical chain reaction, which was supported by the electron paramagnetic resonance results. This study highlights the important role of sulfur conversion in PMS activation by pyrite and provides new insights into the mechanism of oxidant activation by sulfur-containing minerals. Copyright © 2018. Published by Elsevier Ltd.

Eucalyptus development in degraded soil fertilized with sewage sludge and mineral fertilizer

NASA Astrophysics Data System (ADS)

Rodrigues, R. A. F.; Santos, E. B.; Alves, M. C.; Arruda, O. G.

2012-04-01

The aim of this study was to compare the development of eucalyptus in a degraded Oxisol with mineral fertilizer and sewage sludge. The study was conducted in Selviria, Mato Grosso do Sul, Brasil. The culture of eucalyptus was planted in 2003 at 2.0 m x 1.5 m spacing, with application of 60 Mg ha-1 of sewage sludge (dry basis) and mineral fertilizer. After five years (2008) the area received biosolids and mineral fertilizer, and after five months, were evaluated for height and diameter at breast height of Eucalyptus. The experimental design was randomized blocks with four treatments: T1 - control (without addition of inputs), T2 - Mineral fertilization (30 kg ha-1 N, 90 kg ha-1 of P2O5 and 60 kg ha-1 K2O), T3 - Reapplication of 4.64 Mg ha-1 of sewage sludge, dry basis, T4 - Reapplication of 9.28 Mg ha-1 of sewage sludge, dry basis. Before reapplication the biosolids plant height was higher in the eucalyptus with treatment 9.28 Mg ha-1 of sewage sludge (8.03 m) compared to control (5.75 m) and mineral fertilizer (5.91 m) and that treatment 4.64 Mg ha-1 of sewage sludge (6.34 m) did not differ from the previous three. For the diameter at breast height was the highest value for treatment with 9.28 Mg ha-1 (7.78 cm) compared to control (5.23 cm) and 4.64 Mg ha-1 (5.03 cm), and that of mineral fertilizer (5.96 cm) did not differ from all treatments. After reapplication of sludge plant height was higher in the eucalyptus treatment with 9.28 Mg ha-1 of sewage sludge (11.21 m) compared with control (7.51 m), mineral fertilizer (7.77 m) and 4 64 Mg ha-1 (8.07 m), which did not differ. The diameter at breast height had the same behavior before the application of biosolids in the highest value observed being 9.28 Mg ha-1 (8.46 cm) compared with control (5.75 cm) and 4.64 Mg ha-1 (5.03 cm) and that of mineral fertilizer (6.34 cm) did not differ from the others. Reapplication of the dose of 9.28 Mg ha-1 of sewage sludge in degraded Oxisol provided greater height and diameter at breast height from eucalyptus trees.

Iron doped fibrous-structured silica nanospheres as efficient catalyst for catalytic ozonation of sulfamethazine.

PubMed

Bai, Zhiyong; Wang, Jianlong; Yang, Qi

2018-04-01

Sulfonamide antibiotics are ubiquitous pollutants in aquatic environments due to their large production and extensive application. In this paper, the iron doped fibrous-structured silica (KCC-1) nanospheres (Fe-KCC-1) was prepared, characterized, and applied as a catalyst for catalytic ozonation of sulfamethazine (SMT). The effects of ozone dosage, catalyst dosage, and initial concentration of SMT were examined. The experimental results showed that Fe-KCC-1 had large surface area (464.56 m2 g -1 ) and iron particles were well dispersed on the catalyst. The catalyst had high catalytic performance especially for the mineralization of SMT, with mineralization ratio of about 40% in a wide pH range. With addition of Fe-KCC-1, the ozone utilization increased nearly two times than single ozonation. The enhancement of SMT degradation was mainly due to the surface reaction, and the increased mineralization of SMT was due to radical mechanism. Fe-KCC-1 was an efficient catalyst for SMT degradation in catalytic ozonation system.

Characteristics of ZnO nanostructures synthesized by sonochemical reaction: Effects of continuous and pulse waves

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

Widiyastuti, W., E-mail: widi@chem-eng.its.ac.id; Machmudah, Siti; Kusdianto,

Nanostructured ZnO was synthesized by a sonochemical reaction. Ultrasonic irradiation were set up in continuous, pulse in 3 seconds on and a second off (on:off=3:1), and pulse in 2 seconds on and a second off (on:off=2:1) wave modes for 1.5 hours. The characteristics of particles generated by these modes such as morphology, crystallinity, FTIR, photoluminescence, and photocatalytic activity to degrade methylene blue were compared. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The morphology of the generated ZnO particles could be tuned from flower-like, needle- or hairy-like, and spherical structures by changingmore » the mode of ultrasonic irradiation from continuous, on:off=3:1, and on:off=2:1 modes, respectively. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed. The crystalline sizes of particles generated in continuous, on:off=3:1, and on:off=2:1 modes were 28, 27, 24 nm. A similar position of reduction peak of FTIR in all samples indicated that no differences in particles chemical bonding characteristics. Photoluminescence intensity was also decreased with changes the wave mode from continuous to pulse. Photocatalytic activity was also evaluated resulting in particles synthesized by continuous mode had the highest methylene blue degradation degree following by on:off=3:1, and on:off=2:1 modes.« less

Characteristics of ZnO nanostructures synthesized by sonochemical reaction: Effects of continuous and pulse waves

NASA Astrophysics Data System (ADS)

Widiyastuti, W.; Machmudah, Siti; Kusdianto, Nurtono, Tantular; Winardi, Sugeng

2015-12-01

Nanostructured ZnO was synthesized by a sonochemical reaction. Ultrasonic irradiation were set up in continuous, pulse in 3 seconds on and a second off (on:off=3:1), and pulse in 2 seconds on and a second off (on:off=2:1) wave modes for 1.5 hours. The characteristics of particles generated by these modes such as morphology, crystallinity, FTIR, photoluminescence, and photocatalytic activity to degrade methylene blue were compared. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The morphology of the generated ZnO particles could be tuned from flower-like, needle- or hairy-like, and spherical structures by changing the mode of ultrasonic irradiation from continuous, on:off=3:1, and on:off=2:1 modes, respectively. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed. The crystalline sizes of particles generated in continuous, on:off=3:1, and on:off=2:1 modes were 28, 27, 24 nm. A similar position of reduction peak of FTIR in all samples indicated that no differences in particles chemical bonding characteristics. Photoluminescence intensity was also decreased with changes the wave mode from continuous to pulse. Photocatalytic activity was also evaluated resulting in particles synthesized by continuous mode had the highest methylene blue degradation degree following by on:off=3:1, and on:off=2:1 modes.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

A new role for HERPUD1 and ERAD activation in osteoblast differentiation and mineralization.

PubMed

Américo-Da-Silva, Luan; Diaz, Jheimmy; Bustamante, Mario; Mancilla, Georthan; Oyarzún, Ingrid; Verdejo, Hugo E; Quiroga, Clara

2018-03-23

Bone integrity depends on a finely tuned balance between bone synthesis by osteoblasts and resorption by osteoclasts. The secretion capacity of mature osteoblasts requires strict control of proteostasis. Endoplasmic reticulum-associated degradation (ERAD) prevents the accumulation of unfolded ER proteins via dislocation to the cytosol and degradation by the proteasome. The ER membrane protein, homocysteine-inducible endoplasmic reticulum protein with ubiquitin-like domain 1 (HERPUD1), is a key component of the ERAD multiprotein complex which helps to stabilize the complex and facilitate the efficient degradation of unfolded proteins. HERPUD1 expression is strongly up-regulated by the unfolded protein response and cellular stress. The aim of the current study was to establish whether HERPUD1 and ERAD play roles in osteoblast differentiation and maturation. We evaluated preosteoblastic MC3T3-E1 cell and primary rat osteoblast differentiation by measuring calcium deposit levels, alkaline phosphatase activity, and runt-related transcription factor 2 and osterix expression. We found that ERAD and proteasomal degradation were activated and that HERPUD1 expression was increased as osteoblast differentiation progressed. The absence of HERPUD1 blocked osteoblast mineralization in vitro and significantly reduced alkaline phosphatase activity. In contrast, HERPUD1 overexpression activated the osteoblast differentiation program. Our results demonstrate that HERPUD1 and ERAD are important for the activation of the osteoblast maturation program and may be useful new targets for elucidating bone physiology.-Américo-Da-Silva, L., Diaz, J., Bustamante, M., Mancilla, G., Oyarzún, I., Verdejo, H. E., Quiroga, C. A new role for HERPUD1 and ERAD activation in osteoblast differentiation and mineralization.

Removal and mineralization of polycyclic aromatic hydrocarbons by litter-decomposing basidiomycetous fungi.

PubMed

Steffen, K T; Hatakka, A; Hofrichter, M

2002-10-01

Nine strains of litter-decomposing fungi, representing eight species of agaric basidiomycetes, were tested for their ability to remove a mixture of three polycyclic aromatic hydrocarbons (PAHs) (total 60 mg l(-1)) comprising anthracene, pyrene and benzo(a)pyrene (BaP) in liquid culture. All strains were able to convert this mixture to some extent, but considerable differences in degradative activity were observed depending on the species, the Mn(II) concentration, and the particular PAH. Stropharia rugosoannulata was the most efficient degrader, removing or transforming BaP almost completely and about 95% of anthracene and 85% of pyrene, in cultures supplemented with 200 micro M Mn(II), within 6 weeks. In contrast less than 40, 18, and 50% BaP, anthracene and pyrene, respectively, were degraded in the absence of supplemental Mn(II). In the case of Stropharia coronilla, the presence of Mn(II) led to a 20-fold increase of anthracene conversion. The effect of manganese could be attributed to the stimulation of manganese peroxidase (MnP). The maximum activity of MnP increased in S. rugosoannulata cultures from 10 U l(-1) in the absence of Mn(II) to 320 U l(-1) in Mn(II)-supplemented cultures. The latter degraded about 6% of a (14)C-labeled BaP into (14)CO(2) whereas only 0.7% was mineralized in the absence of Mn(II). In solid-state straw cultures, S. rugosoannulata, S. coronilla and Agrocybe praecox mineralized between 4 and 6% of (14)C-labeled BaP within 12 weeks.

Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

PubMed

Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

2016-12-01

Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization.

Characterization of a novel Pseudomonas sp. that mineralizes high concentrations of pentachlorophenol.

PubMed Central

Radehaus, P M; Schmidt, S K

1992-01-01

A pentachlorophenol (PCP)-mineralizing bacterium was isolated from polluted soil and identified as Pseudomonas sp. strain RA2. In batch cultures, Pseudomonas sp. strain RA2 used PCP as its sole source of carbon and energy and was capable of completely degrading this compound as indicated by radiotracer studies, stoichiometric release of chloride, and biomass formation. Pseudomonas sp. strain RA2 was able to mineralize a higher concentration of PCP (160 mg liter-1) than any previously reported PCP-degrading pseudomonad. At a PCP concentration of 200 mg liter-1, cell growth was completely inhibited and PCP was not degraded, although an active population of Pseudomonas sp. RA2 was still present in these cultures after 2 weeks. The inhibitory effect of PCP was partially attributable to its effect on the growth rate of Pseudomonas sp. strain RA2. The highest specific growth rate (mu = 0.09 h-1) was reached at a PCP concentration of 40 mg liter-1 but decreased at higher or lower PCP concentrations, with the lowest mu (0.05 h-1) occurring at 150 mg liter-1. Despite this reduction in growth rate, total biomass production was proportional to PCP concentration at all PCP concentrations degraded by Pseudomonas sp. RA2. In contrast, final cell density was reduced to below expected values at PCP concentrations greater than 100 mg liter-1. These results indicate that, in addition to its effect as an uncoupler of oxidative phosphorylation, PCP may also inhibit cell division in Pseudomonas sp. strain RA2.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1444401

Nonlinear damage detection in composite structures using bispectral analysis

NASA Astrophysics Data System (ADS)

Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele

2014-03-01

Literature offers a quantitative number of diagnostic methods that can continuously provide detailed information of the material defects and damages in aerospace and civil engineering applications. Indeed, low velocity impact damages can considerably degrade the integrity of structural components and, if not detected, they can result in catastrophic failure conditions. This paper presents a nonlinear Structural Health Monitoring (SHM) method, based on ultrasonic guided waves (GW), for the detection of the nonlinear signature in a damaged composite structure. The proposed technique, based on a bispectral analysis of ultrasonic input waveforms, allows for the evaluation of the nonlinear response due to the presence of cracks and delaminations. Indeed, such a methodology was used to characterize the nonlinear behaviour of the structure, by exploiting the frequency mixing of the original waveform acquired from a sparse array of sensors. The robustness of bispectral analysis was experimentally demonstrated on a damaged carbon fibre reinforce plastic (CFRP) composite panel, and the nonlinear source was retrieved with a high level of accuracy. Unlike other linear and nonlinear ultrasonic methods for damage detection, this methodology does not require any baseline with the undamaged structure for the evaluation of the nonlinear source, nor a priori knowledge of the mechanical properties of the specimen. Moreover, bispectral analysis can be considered as a nonlinear elastic wave spectroscopy (NEWS) technique for materials showing either classical or non-classical nonlinear behaviour.

Removal of high concentration p-nitrophenol in aqueous solution by zero valent iron with ultrasonic irradiation (US-ZVI).

PubMed

Lai, Bo; Chen, Zhaoyu; Zhou, Yuexi; Yang, Ping; Wang, Juling; Chen, Zhiqiang

2013-04-15

In this study, the US-ZVI system was used to produce the strong reductants including H and nascent Fe(2+) ions to eliminate the toxicity of the high concentration p-nitrophenol (PNP) wastewater. The effect of the reactor structure, initial pH, ZVI dosage, ultrasonic power and initial PNP concentration on the removal efficiency of PNP from water was investigated intensively. The results show that a higher removal rate can be obtained by using a conical structure reactor, and the lower initial pH can aid the acceleration of PNP removal rate by using US-ZVI system. Furthermore, the removal efficiencies of PNP increased obviously with the increase of initial ZVI concentration from 0 to 15 gL(-1). Also, the treatment capacity of ZVI was enhanced remarkably by the ultrasonic irradiation, and the US-ZVI system can maintain high treatment efficiency for the high concentration PNP wastewater (500-10,000 mgL(-1)). Meanwhile, the high removal efficiency of PNP was mainly resulted from the synergistic reaction of ZVI and US. At last, the main degradation product (i.e., p-aminophenol) was detected by gas chromatography-mass spectrum (GC-MS). Thus, the reaction pathway of PNP in the US-ZVI system is proposed as a reducing process by the H and nascent Fe(2+) ions. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

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

Almansouri, Hani; Clayton, Dwight A; Kisner, Roger A

Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structuresmore » are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well's health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.« less

Influence of 2,4,6-trinitrotoluene (TNT) concentration on the degradation of TNT in explosive-contaminated soils by the white rot fungus Phanerochaete chrysosporium.

PubMed Central

Spiker, J K; Crawford, D L; Crawford, R L

1992-01-01

The ability of Phanerochaete chrysosporium to bioremediate TNT (2,4,6-trinitrotoluene) in a soil containing 12,000 ppm of TNT and the explosives RDX (hexahydro-1,3,5-trinitro-1,3,5- triazine; 3,000 ppm) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine; 300 ppm) was investigated. The fungus did not grow in malt extract broth containing more than 0.02% (wt/vol; 24 ppm of TNT) soil. Pure TNT or explosives extracted from the soil were degraded by P. chrysosporium spore-inoculated cultures at TNT concentrations of up to 20 ppm. Mycelium-inoculated cultures degraded 100 ppm of TNT, but further growth was inhibited above 20 ppm. In malt extract broth, spore-inoculated cultures mineralized 10% of added [14C]TNT (5 ppm) in 27 days at 37 degrees C. No mineralization occurred during [14C]TNT biotransformation by mycelium-inoculated cultures, although the TNT was transformed. PMID:1444437

Isolation and characterization of a bacterium able to degrade high concentrations of iprodione.

PubMed

Cao, Li; Shi, Wenhong; Shu, Rundong; Pang, Jian; Liu, Yuetao; Zhang, Xiaohua; Lei, Yuming

2018-01-01

A bacterial strain CQH-1 capable of mineralizing iprodione was isolated and characterized. On the basis of its morphological, physiological, and biochemical characteristics combined with phylogenetic analysis of its 16S rRNA gene sequence, strain CQH-1 was identified as a Microbacterium sp. CQH-1. It was able to use iprodione and 3,5-dichloroaniline as the sole source of carbon and energy for its growth. It completely degraded 100 mg·L -1 iprodione within 96 h at 30 °C. During the degradation of iprodione by strain CQH-1, 2 compounds were detected in GC-MS analysis and were recognized as N-(3,5-dichlorophenyl)-2,4-dioxoimidazolidine and 3,5-dichloroaniline. So, the biodegradation pathway of iprodione by strain CQH-1 was proposed. This is the first report of an iprodione-mineralizing strain from the genus Microbacterium, and strain CQH-1 might be a promising candidate for application in the bioremediation of iprodione-contaminated environments.

Self-powering/self-cleaning electronic-skin basing on PVDF/TiO2 nanofibers for actively detecting body motion and degrading organic pollutants

NASA Astrophysics Data System (ADS)

Dong, Chuanyi; Fu, Yongming; Zang, Weili; He, Haoxuan; Xing, Lili; Xue, Xinyu

2017-09-01

A flexible self-powering/self-cleaning electronic-skin (e-skin) for actively detecting body motion and degrading organic pollutants has been fabricated from PVDF/TiO2 nanofibers. PVDF/TiO2 nanofibers are synthesized by high voltage electrospinning method. The e-skin can be driven by external mechanical vibration, and actively output piezoelectric impulse. The outputting piezoelectric voltage can be significantly influenced by different applied deformation, acting as both the body-motion-detecting signal and the electricity power for driving the device. The e-skin can detect various body motions, such as pressing, stretching, bending finger and clenching fist. The e-skin also has distinct self-cleaning characteristic through piezo-photocatalytic coupling process. The photocatalytic activity of TiO2 and the piezoelectric effect of PVDF are coupled in a single physical/chemical process, which can efficiently degrade organic pollutants on the e-skin. For example, methylene blue (MB) can be completely degraded within 40 min under UV/ultrasonic irradiation. The present results could provoke a possible new research direction for realizing self-powering multifunctional e-skin.

Degradation of nicotine in water solutions using a water falling film DBD plasma reactor: direct and indirect treatment

NASA Astrophysics Data System (ADS)

Krupež, Jelena; Kovačević, Vesna V.; Jović, Milica; Roglić, Goran M.; Natić, Maja M.; Kuraica, Milorad M.; Obradović, Bratislav M.; Dojčinović, Biljana P.

2018-05-01

Nicotine degradation efficiency in water solutions was studied using a water falling film dielectric barrier discharge (DBD) reactor. Two different treatments were applied: direct treatment, the recirculation of the solution through a DBD reactor, and indirect treatment, the bubbling of the gas from the DBD through the porous filter into the solution. In a separate experiment, samples spiked with nicotine in double distilled water (ddH2O) and tap water were studied and compared after both treatments. Furthermore, the effects of the homogeneous catalysts, namely, Fe2+ and H2O2, were tested in the direct treatment. Nicotine degradation efficiency was determined using high-performance liquid chromatography. A degradation efficiency of 90% was achieved after the direct treatment catalyzed with Fe2+. In order to analyze the biodegradability, mineralization level, and toxicity of the obtained solutions, after all degradation procedures the values of the following parameters were determined: total organic carbon, chemical oxygen demand, biochemical oxygen demand, and the Artemia salina toxicity test. The results showed that an increase in biodegradability was obtained, after all treatments. A partial nicotine mineralization was achieved and the mortality of the A. salina organism decreased in the treated samples, all of which indicating the effective removal of nicotine and the creation of less toxic solutions. Nicotine degradation products were identified using ultrahigh-performance liquid chromatography coupled with a linear ion trap Orbitrap hybrid mass spectrometer and a simple mechanism for oxidative degradation of nicotine in non-thermal plasma systems is proposed.

Assessment of reaction intermediates of gamma radiation-induced degradation of ofloxacin in aqueous solution.

PubMed

Changotra, Rahil; Guin, Jhimli Paul; Varshney, Lalit; Dhir, Amit

2018-06-01

Gamma radiolytic degradation of an antibiotic, ofloxacin (OFX) was investigated under different experimental conditions. The parameters such as initial OFX concentration, solution pH, absorbed dose and the concentrations of inorganic (CO 3 2- ) and organic (t-BuOH) additives were optimized to achieve the efficient degradation of OFX. The degradation dose constant values of OFX were calculated as 2.364, 1.159, 0.776 and 0.618 kGy -1 for the initial OFX concentrations of 0.05, 0.1, 0.15 and 0.2 mM with their corresponding (G (-OFX)) values of 0.481, 0.684, 1.755 and 1.971, respectively. Degradation rate of OFX was significantly increased with increase in the absorbed dose and decrease in the initial OFX concentration under acidic condition when compared to neutral or alkaline condition. Reaction of OFX in the presence of CO 3 2- and t-BuOH showed that the degradation was primarily caused by the reaction of OFX with radiolytically generated reactive hydroxyl radicals. Mineralization extent of OFX was determined in terms of percentage reduction in total organic carbon (TOC) and results revealed that the addition of H 2 O 2 enhanced the mineralization of OFX from 29% to 36.1% with H 2 O 2 dose of 0.5 mM at an absorbed dose of 3.0 kGy. Based on the LC-QTOF-MS analysis, gamma radiolytic degradation intermediates/products of OFX were identified and the possible degradation pathways of OFX were proposed. Cytotoxicity study of the irradiated OFX solutions showed that gamma radiation has potential to detoxify OFX. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative studies in electrochemical degradation of sulfamethoxazole and diclofenac in water by using various electrodes and phosphate and sulfate supporting electrolytes.

PubMed

Sifuna, Fred W; Orata, Francis; Okello, Veronica; Jemutai-Kimosop, Selly

2016-09-18

In this study, the electro-oxidation capacities of Na2SO4 and potassium phosphate buffer supporting electrolytes were tested and compared for destruction of the sulfamethoxazole (SMX) and diclofenac (DCF) on platinum (Pt) electrode and graphite carbon electrode in aqueous medium. The suitability of pharmaceutical active compounds (PhACs) for electrochemical oxidation was tested by cyclic voltammetry (CV) technique performed in the potential range -1.5 to +1.5 V versus Ag/AgCl, which confirmed the electro-activity of the selected PhACs. The degradation and mineralization were monitored by ultraviolet (UV)-Vis spectrophotometry and HPLC. 0.1 M Na2SO4 supporting electrolyte was found to be more effective for mineralization of SMX and DCF, with efficiency of 15-30% more than the 0.1 M phosphate buffer supporting electrolyte on the platinum (Pt) and carbon electrodes. The Pt electrode showed better performance in the degradation of the two PhACs while under the same conditions than the carbon electrode for both 0.1 M Na2SO4 and 0.1 M potassium phosphate buffer supporting electrolytes. The SMX and DCF degradation kinetics best fitted the second-order reaction, with rate constants ranging between 0.000389 and 0.006 mol(2) L(-2) min(-1) and correlation coefficient (R(2)) above 0.987. The second-order degradation kinetics indicated that the rate-determining step in the degradation could be a chemical process, thus suggesting the active involvement of electrolyte radical species in the degradation of SMX and DCF. Results obtained from a real field sample showed a more than 98% removal of the PhACs from the wastewater by electrochemical degradation.

The efficacy of an oxidation pond in mineralizing some industrial waste products with special reference to fluorene degradation: A case study

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

Ahmed, M.T.; Dewedar, A.; Mekki, L.

1999-07-01

The efficacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city in Egypt, was examined. Samples of wastewater collected from the inlet and the outlet were screened for some priority pollutants. Acenaphethene and fluorene were the most frequently detected polycyclic aromatic hydrocarbons, while dimethyl phthalate was the most frequently detected phthalate ester. The spectrum of pollutants, their concentrations and frequencies were similar in the inlet and the outlet, indicating an inferior mineralization capability of the pond. Several degradative bacterial strains were isolated from the pond and grown on M56 minimal media supplemented withmore » different pollutants as the carbon source. The efficacy of pure and mixed cultures to break down fluorene, the most frequently detected pollutant was examined. Fluorene degradation was fast in the first 10 days, the followed by a slow phase. Mixed culture had a higher rate of fluorene degradation in comparison to pure cultures. High performance liquid chromatography analysis of fluorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identified as acetamide. The present work has indicated the poor efficacy of the pond. Lack of primary treatment of industrial effluent at factory level, coupled with shock loads of toxicants that may damage the microorganisms and their degradative capabilities are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to fluctuate and change depending on the rate from the factories discharge and work shifts. Such irregular feeding of persistent pollutants may have led to a wash out of specialized strains of bacteria capable to degrade such persistent pollutants.« less

Investigation of the synergistic effects for p-nitrophenol mineralization by a combined process of ozonation and electrolysis using a boron-doped diamond anode.

PubMed

Qiu, Cuicui; Yuan, Shi; Li, Xiang; Wang, Huijiao; Bakheet, Belal; Komarneni, Sridhar; Wang, Yujue

2014-09-15

Electrolysis and ozonation are two commonly used technologies for treating wastewaters contaminated with nitrophenol pollutants. However, they are often handicapped by their slow kinetics and low yields of total organic carbon (TOC) mineralization. To improve TOC mineralization efficiency, we combined electrolysis using a boron-doped diamond (BDD) anode with ozonation (electrolysis-O3) to treat a p-nitrophenol (PNP) aqueous solution. Up to 91% TOC was removed after 60 min of the electrolysis-O3 process. In comparison, only 20 and 44% TOC was respectively removed by individual electrolysis and ozonation treatment conducted under similar reaction conditions. The result indicates that when electrolysis and ozonation are applied simultaneously, they have a significant synergy for PNP mineralization. This synergy can be mainly attributed to (i) the rapid degradation of PNP to carboxylic acids (e.g., oxalic acid and acetic acid) by O3, which would otherwise take a much longer time by electrolysis alone, and (ii) the effective mineralization of the ozone-refractory carboxylic acids to CO2 by OH generated from multiple sources in the electrolysis-O3 system. The result suggests that combining electrolysis with ozonation can provide a simple and effective way to mutually compensate the limitations of the two processes for degradation of phenolic pollutants. Copyright © 2014 Elsevier B.V. All rights reserved.

Microbial mineralization of cis-dichloroethene and vinyl chloride as a component of natural attenuation of chloroethene contaminants under conditions identified in the field as anoxic

USGS Publications Warehouse

Bradley, Paul M.

2012-01-01

Chlororespiration is a key component of remediation at many chloroethene-contaminated sites. In some instances, limited accumulation of reductive dechlorination daughter products may suggest that natural attenuation is not adequate for site remediation. This conclusion is justified when evidence for parent compound (tetrachloroethene, PCE, or trichloroethene, TCE) degradation is lacking. For many chloroethene-contaminated shallow aquifer systems, however, non-conservative losses of the parent compounds are clear but the mass balance between parent compound attenuation and accumulation of reductive dechlorination daughter products is incomplete. Incomplete mass balance indicates a failure to account for important contaminant attenuation mechanisms, and is consistent with contaminant degradation to non-diagnostic mineralization products. An ongoing technical debate over the potential for mineralization of dichloroethene (DCE) and vinyl chloride (VC) to CO2 in the complete absence of diatomic oxygen has largely obscured the importance of microbial DCE/VC mineralization at dissolved oxygen (DO) concentrations below the current field standard (DO < 0.1-0.5 milligrams per liter) for nominally anoxic conditions. This study demonstrates that oxygen-based microbial mineralization of DCE and VC can be substantial under field conditions that are frequently characterized as "anoxic." Because mischaracterization of operant contaminant biodegradation processes can lead to expensive and ineffective remedial actions, a modified framework for assessing the potential importance of oxygen during chloroethene biodegradation was developed.

Rhizosphere Bacterial Degradation of RDX, Understanding and Enhancement

DTIC Science & Technology

2014-02-01

and other explosives collected, and Paul Higgs (Environmental Coordinator) supplied contaminated soils from Milan Army Ammunition Plant (MAAP; Milan...JS178 (Fournier, Trott et al. 2005) and degraded by Phanerochaete chrysosporium (Fournier, Halasz et al. 2004). Thus, complete mineralization often... innovation , since their replication is independent of the chromosome and they do not generally encode essential functions. Although it was earlier suggested

Aerobic microorganism for the degradation of chlorinated aliphatic hydrocarbons

DOEpatents

Fliermans, Carl B.

1989-01-01

A chlorinated aliphatic hydrocarbon-degrading microorganism, having American Type Culture Collection accession numbers ATCC 53570 and 53571, in a biologically pure culture aseptically collected from a deep subsurface habitat and enhanced, mineralizes trichloroethylene and tetrachloroethylene to HCl, H.sub.2 O and Co.sub.2 under aerobic conditions stimulated by methane, acetate, methanol, tryptone-yeast extract, propane and propane-methane.

Isolation of a thermophilic bacterium capable of low-molecular-weight polyethylene degradation.

PubMed

Jeon, Hyun Jeong; Kim, Mal Nam

2013-02-01

A thermophilic bacterium capable of low-molecular-weight polyethylene (LMWPE) degradation was isolated from a compost sample, and was identified as Chelatococcus sp. E1, through sequencing of the 16S rRNA gene. LMWPE was prepared by thermal degradation of commercial PE in a strict nitrogen atmosphere. LMWPE with a weight-average-molecular-weight (Mw) in the range of 1,700-23,700 was noticeably mineralized into CO(2) by the bacterium. The biodegradability of LMWPE decreased as the Mw increased. The low molecular weight fraction of LMWPE decreased significantly as a result of the degradation process, and thereby both the number-average-molecular-weight and Mw increased after biodegradation. The polydispersity of LMWPE was either narrowed or widened, depending on the initial Mw of LMWPE, due to the preferential elimination of the low molecular weight fraction, in comparison to the high molecular weight portion. LMWPE free from an extremely low molecular weight fraction was also mineralized by the strain at a remarkable rate, and FTIR peaks assignable to C-O stretching appeared as a result of microbial action. The FTIR peaks corresponding to alkenes also became more intense, indicating that dehydrogenations occurred concomitantly with microbial induced oxidation.

Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications*

PubMed Central

Panwar, Preety; Lamour, Guillaume; Mackenzie, Neil C. W.; Yang, Heejae; Ko, Frank; Li, Hongbin; Brömme, Dieter

2015-01-01

During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging. PMID:26224630

Sequential reductive and oxidative biodegradation of chloroethenes stimulated in a coupled bioelectro-process.

PubMed

Lohner, Svenja T; Becker, Dirk; Mangold, Klaus-Michael; Tiehm, Andreas

2011-08-01

This article for the first time demonstrates successful application of electrochemical processes to stimulate sequential reductive/oxidative microbial degradation of perchloroethene (PCE) in mineral medium and in contaminated groundwater. In a flow-through column system, hydrogen generation at the cathode supported reductive dechlorination of PCE to cis-dichloroethene (cDCE), vinyl chloride (VC), and ethene (ETH). Electrolytically generated oxygen at the anode allowed subsequent oxidative degradation of the lower chlorinated metabolites. Aerobic cometabolic degradation of cDCE proved to be the bottleneck for complete metabolite elimination. Total removal of chloroethenes was demonstrated for a PCE load of approximately 1.5 μmol/d. In mineral medium, long-term operation with stainless steel electrodes was demonstrated for more than 300 days. In contaminated groundwater, corrosion of the stainless steel anode occurred, whereas DSA (dimensionally stable anodes) proved to be stable. Precipitation of calcareous deposits was observed at the cathode, resulting in a higher voltage demand and reduced dechlorination activity. With DSA and groundwater from a contaminated site, complete degradation of chloroethenes in groundwater was obtained for two months thus demonstrating the feasibility of the sequential bioelectro-approach for field application.

The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

PubMed

Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

2016-07-01

In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. Copyright © 2016. Published by Elsevier B.V.

Microbial degradation and toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine.

PubMed

Khan, Muhammad Imran; Lee, Jaejin; Park, Joonhong

2012-10-01

In the present work, current knowledge on the potential fate, microbial degradation, and toxicity of hexahydro- 1,3,5-trinitro-1,3,5-triazine (RDX) was thoroughly reviewed, focusing on the toxicological assessment of a variety of potential RDX degradation pathways in bacteria and fungi. The present review on microbial degradation pathways and toxicities of degradation intermediates suggests that, among aerobic RDX degradation pathways, the one via denitration may be preferred in a toxicological perspective, and that among anaerobic pathways, those forming 4- nitro-2,4-diazabutanal (NDAB) via ring cleavage of 1-nitroso- 3,5-dinitro-1,3,5-triazinane (MNX) may be toxicologically advantageous owing to its potential mineralization under partial or complete anoxic conditions. These findings provide important information on RDX-degrading microbial pathways, toxicologically most suitable to be stimulated in contaminated fields.

Effect of pH on the adsorption and photocatalytic degradation of sulfadimidine in Vis/g-C3N4 progress.

PubMed

Yang, Bin; Mao, Xuhui; Pi, Liu; Wu, Yixiao; Ding, Huijun; Zhang, Weihao

2017-03-01

In this study, g-C 3 N 4 was synthesized by thermal polycondensation of melamine and was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy, and scanning electron microscopy. Results showed that g-C 3 N 4 degraded sulfadimidine (SMD) under visible light, in which the adsorption and photocatalytic degradation was influenced by pH. The maximum adsorption capacity was achieved at approximately pH 5. The highest degradation rate constant was obtained at strong acid and alkali. In addition, the degradation mechanism of g-C 3 N 4 was evaluated with the help of quencher agents. The intermediates, degradation pathways, and mineralization of SMD were also determined to evaluate the degradation and oxidation ability of g-C 3 N 4 .

[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.

Nitrogen mineralization and geochemical characteristics of amino acids in surface sediments of a typical polluted area in the Haihe River Basin, China.

PubMed

Zhao, Yu; Shan, Baoqing; Tang, Wenzhong; Zhang, Hong

2015-11-01

Studies of nitrogen mineralization and diagenetic status of organic matter evaluated by total hydrolysable amino acids (THAAs) were designed to test the hypothesis that nitrogen mineralization in sediments was a potential source of ammonium in strongly artificially disturbed rivers such as the Ziya River watershed. Ammonium and organic nitrogen in both water and sediment samples were the major forms of nitrogen in the watershed. NH3-N was significantly correlated with organic nitrogen in both water (R = 0.823, P < 0.01) and sediments (R = 0.787, P < 0.01). Organic nitrogen with an average content of 3,275.21 ± 1,476.10 mg · kg(-1), accounted for 82.73 % of total nitrogen (TN) in sediments. Organic nitrogen was a potential source of ammonia release into overlying water. Nitrogen mineralization experiments showed that accumulated dissolved inorganic nitrogen ranged from 326.15 to 545.72 mg · kg(-1) and accumulated NH3-N ranged from 320.95 to 533.93 mg · kg(-1). Most of the mineralized nitrogen was NH3-N ( approximately 98.17%) and mineralized nitrogen in sediments ranged from 6.20 to 22.10% of TN. Twenty amino acids were detected, accounting for 45.70 % of organic nitrogen. Protein amino acids, accounting for 89.22% of THAAs, were the dominant THAAs in sediments. The ratio of L-glutamic acid to γ-aminobutyric acid and degradation index showed that the organic matter was poorly degraded and presented a high potential risk of ammonium mineralization.

Interaction, at Ambient Temperature and 80 °C, between Minerals and Artificial Seawaters Resembling the Present Ocean Composition and that of 4.0 Billion Years Ago

NASA Astrophysics Data System (ADS)

Carneiro, Cristine E. A.; Stabile, Antonio C.; Gomes, Frederico P.; da Costa, Antonio C. S.; Zaia, Cássia T. B. V.; Zaia, Dimas A. M.

2017-09-01

Probably one of the most important roles played by minerals in the origin of life on Earth was to pre-concentrate biomolecules from the prebiotic seas. There are other ways to pre concentrate biomolecules such as wetting/drying cycles and freezing/sublimation. However, adsorption is most important. If the pre-concentration did not occur—because of degradation of the minerals—other roles played by them such as protection against degradation, formation of polymers, or even as primitive cell walls would be seriously compromised. We studied the interaction of two artificial seawaters with kaolinite, bentonite, montmorillonite, goethite, ferrihydrite and quartz. One seawater has a major cation and anion composition similar to that of the oceans of the Earth 4.0 billion years ago (ASW 4.0 Ga). In the other, the major cations and anions are an average of the compositions of the seawaters of today (ASWT). When ASWT, which is rich in Na+ and Cl-, interacted with bentonite and montmorrilonite structural collapse occurred on the 001 plane. However, ASW 4.0 Ga, which is rich in Mg2+ and SO4 2-, did not induce this behavior. When ASW 4.0 Ga was reacted with the minerals for 24 h at room temperature and 80 °C, the release of Si and Al to the fluid was below 1 % of the amount in the minerals—meaning that dissolution of the minerals did not occur. In general, minerals adsorbed Mg2+ and K+ from the ASW 4.0 Ga and these cations could be used for the formation of polymers. Also, when the minerals were mixed with ASW 4.0 Ga at 80 °C and ASWT at room temperature or 80 °C it caused the precipitation of CaSO4•2H2O and halite, respectively. Finally, further experiments (adsorption, formation of polymers, protection of molecules against degradation, primitive cell wall formation) performed under the conditions described in this paper will probably be more representative of what happened on the prebiotic Earth.

Constant and variable amplitude ultrasonic fatigue of 2024-T351 aluminium alloy at different load ratios.

PubMed

Mayer, H; Fitzka, M; Schuller, R

2013-12-01

Ultrasonic fatigue testing equipment is presented that is capable of performing constant amplitude (CA) and variable amplitude (VA) experiments at different constant load ratios. This equipment is used to study cyclic properties of aluminium alloy 2024-T351 in the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) regime at load ratios R=-1 and R=0.5. CA loading does not reveal a fatigue limit below 10¹⁰ cycles. Cracks leading to VHCF failure start at broken constituent particles. Specimens that survived more than 10¹⁰ cycles at R=-1 contain non-propagating cracks of lengths below grain size. Resonance frequency and nonlinearity parameter β(rel) show changes of vibration properties of specimens at low fractions of their VHCF lifetime. VA lifetimes are measured in the HCF and VHCF regime and compared with Miner calculations. Damage sums decrease with decreasing load (and increasing mean lifetimes) and are lower for R=0.5 than R=-1. Copyright © 2013 Elsevier B.V. All rights reserved.

Microbial community structure and biodegradation activity of particle-associated bacteria in a coal tar contaminated creek

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

Jennifer M. DeBruyn; Gary S. Sayler

The Chattanooga Creek Superfund site (Chattanooga, TN) is one of the most polluted waterways in the southeastern U.S. with high polycyclic aromatic hydrocarbon (PAH) concentrations in the sediments. PAHs associate with suspended solids in the water column, and may be redeposited onto the floodplain. These suspended particles represent an interesting but understudied environment for PAH-degrading microbial communities. This study tested the hypotheses that particle-associated bacterial (PAB) communities have genotypic potential (PAH-dioxygenase genes) and activity (naphthalene and pyrene mineralization), and can contribute to natural attenuation of PAHs in Chattanooga Creek. Upstream of the Superfund site, mineralization ranged from 0.2 to 2.0%more » of added {sup 14}C-naphthalene and 0 to 0.1% {sup 14}C-pyrene (after 40 h), with first order biodegradation rate constants (k{sub 1}) ranging from 1.09 to 9.18 x 10{sup -5} h{sup -1} and 0 to 1.13 x 10{sup -6} h{sup -1}, respectively. Mineralization was significantly greater in PAB communities within the contaminated zone, with 11.8 to 31.2% {sup 14}C-naphthalene (k{sup 1} 5.34 to 14.2 x 10-4 h{sup -1}) and 1.3 to 6.6% {sup 14}C-pyrene mineralized (k{sub 1} 2.89 to 15.0 x 10{sup -5} h{sup -1}). Abundances of nagAc (naphthalene dioxygenase) and nidA (pyrene dioxygenase) genes indicated that PAB communities harbored populations with genetic potential for both low- and high-molecular weight PAH degradation, and quantification of Mycobacterium 16S rDNA genes indicated that PAH-degrading mycobacteria are also prevalent in this environment. Phylogenetic comparisons (T-RFLPs) between PAB and sediments indicated these microbial communities were taxonomically distinct, but shared some functional similarities, namely PAH catabolic genotypes, mineralization capabilities, and community structuring along a contamination gradient. 38 refs., 4 figs., 2 tabs.« less

Electrochemical incineration of omeprazole in neutral aqueous medium using a platinum or boron-doped diamond anode: degradation kinetics and oxidation products.

PubMed

Cavalcanti, Eliane Bezerra; Garcia-Segura, Sergi; Centellas, Francesc; Brillas, Enric

2013-04-01

The electrochemical incineration of omeprazole, a widely prescribed gastrointestinal drug which is detected in natural waters, has been studied in a phosphate buffer of pH 7.0 by anodic oxidation with electrogenerated H(2)O(2) (AO-H(2)O(2)) operating at constant current density (j). The experiments were carried out in a cell equipped with either a Pt or a boron-doped diamond (BDD) anode and an air-diffusion cathode to continuously produce H(2)O(2). In these systems, organics are mainly oxidized by hydroxyl radicals formed at the Pt or BDD surface from water oxidation. A partial total organic carbon (TOC) abatement close to 78% for omeprazole was achieved by AO-H(2)O(2) with a BDD anode after consumption of 18 Ah L(-1) at 100 mA cm(-2), whereas the alternative use of Pt did not allow mineralizing the drug. However, the drug was totally removed using both anodes, although it decayed more rapidly using BDD. In this latter system, increasing j accelerated the degradation process, but lowering the mineralization current efficiency. Greater drug content also enhanced the degradation rate with higher mineralization degree and current efficiency. The kinetics for omeprazole decay always followed a pseudo-first-order reaction and its rate constant increased with increasing j and with decreasing its concentration. Seven heteroaromatic intermediates and four hydroxylated derivatives were detected by LC-MS, while nine short-linear carboxylic acids were identified and quantified by ion-exclusion HPLC. These acids were largely accumulated using Pt and rapidly removed using BDD, thus explaining the partial mineralization of omeprazole achieved by AO-H(2)O(2) with the latter anode. The release of inorganic ions such as NO(3)(-), NH(4)(+) and SO(4)(2-) was followed by ionic chromatography. A plausible reaction sequence for omeprazole mineralization involving all intermediates detected is proposed. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-yield synthesis of vaterite microparticles in gypsum suspension system via ultrasonic probe vibration/magnetic stirring

NASA Astrophysics Data System (ADS)

Wang, Bo; Pan, Zihe; Cheng, Huaigang; Chen, Zuliang; Cheng, Fangqin

2018-06-01

Vaterite-type calcium carbonate particles have some unique properties such as high hydrophilicity, large surface areas, and hierarchical structures consisting of primary vaterite particles in comparison with calcite or aragonite-type polymorphs. In this paper, gypsum (CaSO4·2H2O) suspension is used to synthesize micro-sized vaterite CaCO3 through magnetic stirring (MS) and ultrasonic probe vibration (UPV) methods. The effects of ammonia concentration, CO2 flow rate, solid-liquid ratio on the gypsum carbonation process, mineral phase composition, morphology and particle size distribution of CaCO3 are investigated. The results show that the carbonation process is significantly influenced by ammonia concentration, CO2 flow rate and ultrasound. Comparing with magnetic stirring, ultrasonic probe vibration take less time to reach the complete carbonate reaction. Gypsum is transformed to vaterite with the conversion rate about ∼95% when the mole ratio of NH4+/Ca2+ is 2.4 otherwise the carbonation reaction was uncompleted with gypsum residues left. Comparing with MS method, the UPV method resulted in smaller size and narrower size distribution of as-prepared microparticles and approximately 80% reduction of the particle size was achieved. It is established that increasing the solid-liquid ratio resulted in larger particle size in MS system and smaller particle size in UPV system. Increasing CO2 flow rate caused the particle size decreased in MS system and increased in UPV system.

The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

NASA Technical Reports Server (NTRS)

Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

1983-01-01

As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

Solid State Joining of Magnesium to Steel

NASA Astrophysics Data System (ADS)

Jana, Saumyadeep; Hovanski, Yuri; Pilli, Siva P.; Field, David P.; Yu, Hao; Pan, Tsung-Yu; Santella, M. L.

Friction stir welding and ultrasonic welding techniques were applied to join automotive magnesium alloys to steel sheet. The effect of tooling and process parameters on the post-weld microstructure, texture and mechanical properties was investigated. Static and dynamic loading were utilized to investigate the joint strength of both cast and wrought magnesium alloys including their susceptibility and degradation under corrosive media. The conditions required to produce joint strengths in excess of 75% of the base metal strength were determined, and the effects of surface coatings, tooling and weld parameters on weld properties are presented.

Characterization of triclosan metabolism in Sphingomonas sp. strain YL-JM2C

NASA Astrophysics Data System (ADS)

Mulla, Sikandar I.; Wang, Han; Sun, Qian; Hu, Anyi; Yu, Chang-Ping

2016-02-01

Triclosan (TCS) is one of the most widespread emerging contaminants and has adverse impact on aquatic ecosystem, yet little is known about its complete biodegradation mechanism in bacteria. Sphingomonas sp, strain YL-JM2C, isolated from activated sludge of a wastewater treatment plant, was very effective on degrading TCS. Response surface methodology (RSM) was applied to optimize the conditions like temperature and pH. From RSM, the optimal TCS degradation conditions were found to be 30 °C and pH 7.0. Under optimal conditions, strain YL-JM2C completely mineralized TCS (5 mg L-1) within 72 h. Gas chromatography-mass spectrometry analysis revealed that 2,4-dichlorophenol, 2-chlorohydroquinone and hydroquinone are three main by-products of TCS. Furthermore, stable isotope experimental results revealed that the 13C12-TCS was completely mineralized into CO2 and part of heavier carbon (13C) of labeled TCS was utilized by strain YL-JM2C to synthesize fatty acids (PLFAs). Cell surface hydrophobicity (CSH) and degradation test results suggested that the strain could enhance degradation capacity of TCS through increasing CSH. In addition, the bacterium also completely degraded spiked TCS (5 mg L-1) in wastewater collected from the wastewater treatment plant. Hence, these results suggest that the strain has potential to remediate TCS in the environment.

Cold Incineration of Chlorophenols in Aqueous Solution by Advanced Electrochemical Process Electro-Fenton. Effect of Number and Position of Chlorine Atoms on the Degradation Kinetics

NASA Astrophysics Data System (ADS)

Oturan, Nihal; Panizza, Marco; Oturan, Mehmet A.

2009-09-01

This study reports the kinetics of the degradation of several chlorophenols (CPs), such as monochlorophenols (2-chlorophenol and 4-chlorophenol), dichlorophenols (2,4-dichlorophenol and 2,6- dichlorophenol), trichlorophenols (2,3,5- trichlorophenol and 2,4,5-trichlorophenol), 2,3,5,6-tetrachlorophenol, and pentachlorophenol, by the electro-Fenton process using a carbon felt cathode and a Pt anode. The effect of number and the position of the chlorine atoms in the aromatic ring on the oxidative degradation rate was evaluated and discussed. The oxidation reaction of all the CPs with hydroxyl radicals evidenced a pseudo-first-order kinetics and the rate constant decreased with increasing the number of chlorine atoms. The absolute rate constant of second-order reaction kinetics between CPs and •OH was determined by the competition kinetics method in the range of (3.56-7.75) × 109 M-1 s-1 and follows the same sequence of the apparent rate constants. The mineralization of several CPs and of a mixture of all CPs under study was monitored by the total organic carbon (TOC) removal and the chlorine release during mineralization was followed by ion chromatography. Our results demonstrated that more chlorinated phenols are more difficult to mineralize; however for all the tested CPs, almost quantitative release of chloride ions was obtained after 6 h of treatment.

Sequential decolorization of azo dye and mineralization of decolorization liquid coupled with bioelectricity generation using a pH self-neutralized photobioelectrochemical system operated with polarity reversion.

PubMed

Sun, Jian; Hu, Yongyou; Li, Wanjun; Zhang, Yaping; Chen, Jie; Deng, Feng

2015-05-30

A novel photobioelectrochemical system (PBES) was developed by acclimating algal-bacterial biofilm in both anode and cathode using Chlorella vulgaris and indigenous wastewater bacteria as inoculums. The PBES was operated in polarity reversion mode depend on dark/light alternate reaction to achieve simultaneous pH self-neutralization, azo dye degradation (Congo red) and bioelectricity generation. The anodic accumulated acidity and cathodic accumulated alkalinity were self-neutralized after polarity reversion and hence eliminate the membrane pH gradient. The Congo red was first decolored in the dark anode and the resultant decolorization liquid was subsequently mineralized after the dark anode changing to the photo-biocathode. The presence of C. vulgaris significantly enhanced the two-stage degradation of Congo red, with 93% increases in decolorization rates and 8% increases in mineralization compared to the algae-free BES. The PBES continuously generated stable voltage output over four months under repeatedly reversion of polarity. The maximum power density produced before and after polarity reversion was 78 and 61 mW/m(2), respectively. The synergy between C. vulgaris and mixed bacteria was responsible for the successful operation of the PBES which can be potentially applied to treat wastewater containing azo dye with benefits of enhanced azo dye degradation, high net power output and buffer minimization. Copyright © 2015 Elsevier B.V. All rights reserved.

Decreased Bone Mineral Density in Prader-Willi Syndrome: Comparison With Obese Subjects

PubMed Central

Butler, Merlin G.; Haber, Lawrence; Mernaugh, Ray; Carlson, Michael G.; Price, Ron; Feurer, Irene D.

2016-01-01

Bone density, anthropometric data, and markers of bone turnover were collected on 21 subjects diagnosed with Prader-Willi syndrome (PWS) and compared with 9 subjects with obesity of unknown cause. In addition, urinary N-telopeptide levels were obtained in all subjects. N-telopeptides are the peptide fragments of type I collagen, the major bone matrix material. During periods of active bone degradation or high bone turnover, high levels of N-telopeptides are excreted in the urine. However, no significant difference was detected in the urinary N-telopeptide levels when corrected for creatinine excretion (raw or transformed data) between our subjects with obesity or PWS and the observed effect size of the between-group difference was small. Although N-telopeptide levels were higher but not significantly different in the subjects with PWS compared with obese controls, the subjects with PWS had significantly decreased total bone and spine mineral density and total bone mineral content (all P < 0.001). No differences in N- telopeptide levels or bone mineral density were observed between subjects with PWS and chromosome 15q deletion or maternal disomy. Thus, decreased bone mineral density in subjects with PWS may relate to the lack of depositing bone mineral during growth when bones are becoming more dense (e.g., during adolescence), possibly because of decreased production of sex or growth hormones and/or long-standing hypotonia. It may not be caused by loss, or active degradation, of bone matrix measurable by the methods described in this study further supporting the possible need for hormone therapy during adolescence. PMID:11745993

Mineralization of the Cyclic Nitramine Explosive Hexahydro-1,3,5-Trinitro-1,3,5-Triazine by Gordonia and Williamsia spp.

PubMed Central

Thompson, Karen T.; Crocker, Fiona H.; Fredrickson, Herbert L.

2005-01-01

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a cyclic nitroamine explosive that is a major component in many military high-explosive formulations. In this study, two aerobic bacteria that are capable of using RDX as the sole source of carbon and nitrogen to support their growth were isolated from surface soil. These bacterial strains were identified by their fatty acid profiles and 16S ribosomal gene sequences as Williamsia sp. KTR4 and Gordonia sp. KTR9. The physiology of each strain was characterized with respect to the rates of RDX degradation and [U-14C]RDX mineralization when RDX was supplied as a sole carbon and nitrogen source in the presence and absence of competing carbon and nitrogen sources. Strains KTR4 and KTR9 degraded 180 μM RDX within 72 h when RDX served as the only added carbon and nitrogen source while growing to total protein concentrations of 18.6 and 16.5 μg/ml, respectively. Mineralization of [U-14C]RDX to 14CO2 was 30% by strain KTR4 and 27% by KTR9 when RDX was the only added source of carbon and nitrogen. The addition of (NH4)2SO4 greatly inhibited KTR9's degradation of RDX but had little effect on that of KTR4. These are the first two pure bacterial cultures isolated that are able to use RDX as a sole carbon and nitrogen source. These two genera possess different physiologies with respect to RDX mineralization, and each can serve as a useful microbiological model for the study of RDX biodegradation with regard to physiology, biochemistry, and genetics. PMID:16332812

Tracking the Fate of Explosive-Trinitrotriazine (RDX) in Coastal Marine Ecosystems Using Stable Isotopic Tracer

NASA Astrophysics Data System (ADS)

Ariyarathna, T. S.; Ballentine, M.; Vlahos, P.; Smith, R. W.; Bohlke, J. K.; Tobias, C. R.; Fallis, S.; Groshens, T.; Cooper, C.

2017-12-01

It has been estimated that there are hundreds of explosive-contaminated sites all over the world and managing these contaminated sites is an international challenge. As coastal zones and estuaries are commonly impacted zones, it is vital to understand the fate and transport of munition compounds in these environments. The demand for data on sorption, biodegradation and mineralization of trinitrotriazine (RDX) in coastal ecosystems is the impetus for this study using stable nitrogen isotopes to track its metabolic pathways. Mesocosm experiments representing subtidal vegetated, subtidal unvegetated and intertidal marsh ecocosms were conducted. Steady state concentrations of RDX were maintained in the systems throughout two-week time duration of experiments. Sediment, pore-water and overlying water samples were analyzed for RDX and degradation products. Isotope analysis of the bulk sediments revealed an initial rising inventory of 15N followed by a decay illustrating the role of sediments on sorption and degradation of RDX in anaerobic sediments respectively. Both pore-water and overlying water samples were analyzed for 15N inventories of different inorganic nitrogen pools including ammonium, nitrate, nitrite, nitrous oxide and nitrogen gases. RDX is mineralized to nitrogen gas through a series of intermediates leaving nitrous oxide as the prominent metabolite of RDX. Significant differences in RDX metabolism were observed in the three different ecosystems based on sediment characteristics and redox conditions in the systems. Fine grained organic carbon rich sediments show notably higher mineralization rates of RDX in terms of production of its metabolites. Quantification of degradation and transformation rates leads to mass balances of RDX in the systems. Further analysis of results provides insights for mineralization pathways of RDX into both organic and inorganic nitrogen pools entering the marine nitrogen cycle.

On the Mineral and Vegetal Oils Used as Electroinsulation in Transformers

NASA Astrophysics Data System (ADS)

Şerban, Mariana; Sângeorzan, Livia; Helerea, Elena

Due to the relatively large availability and reduced price, the mineral transformer oils are widely used as electrical insulating liquids. However, mineral oil drastically degrades over time in service. New efforts were made to improve mineral oils characteristics, and other types of liquids like vegetal oils are proposed. This paper deals with new comparative tests on mineral and vegetal oils using as indicator the electric strength. The samples of non-additive mineral oil type TR 30 and vegetal oils of rape, sunflower and corn have been tested with increasing voltage of 60 Hz using different electrodes. The obtained data have been statistical processed. The analyze shows different average values of electrical strength for the different type of sample. New method of testing through electrical breakdown is proposed. Experimental data confirms that it is possible to use as electroinsulation organic vegetal oils in power transformers.

Soil physicochemical properties to evaluate soil degradation under different land use types in a high rainfall tropical region: A case study from South Sulawesi, Indonesia

NASA Astrophysics Data System (ADS)

Ahmad, A.; Lopulisa, C.; Imran, A. M.; Baja, S.

2018-05-01

Intensive cropping in the tropical region always becomes one of important driving forces of soil degradation. The primary aim of this study is to analyze the states and the dynamics of soil physicochemical properties to evaluate soil degradation in the tropical region a high rainfall on agricultural areas in South Sulawesi. A number of soil characteristics were analyzed for physical and chemical properties, and clay minerals with X-ray diffractometer. The degree of soil degradation is determined using Wischmeier and Smith equation. This study reveals that mean annual precipitation in 1979-2016 ranged from 1853.15 to 2981.30 mm/year. For land used for paddy field, palm oil, cacao and coffee plantation, the texture dominated with silt loam-clay loam, cation exchange capacity was 18.63-26.32 cmol+ kg-1, 0.98-2.91% of C-organic, 32-55% of base saturation, 0.1-3.5 cm h-1 of permeability, soil clay minerals were montmorillonite-kaolinite-halloysite, and the index erodibility was 0.3-0.5. Land used for mixed plants and shrubs, the texture dominated with silt loam-sandy clay loam, cation exchange capacity was 18.63-27.12 cmol+ kg-1, 1.09-2.89% of C-organic, 32-55% of base saturation, 0.2-4.9 cm/h of permeability, soil clay minerals were kaolinite-halloysite, and index erodibility was 0.1-0.3. Land use for cultivated in the high intensity of rainfall has changed the physicochemical properties of soils, but cultivated in monoculture has at some degree increased soil erodibility.

Rapid Acyl-Homoserine Lactone Quorum Signal Biodegradation in Diverse Soils†

PubMed Central

Wang, Ya-Juan; Leadbetter, Jared Renton

2005-01-01

Signal degradation impacts all communications. Although acyl-homoserine lactone (acyl-HSL) quorum-sensing signals are known to be degraded by defined laboratory cultures, little is known about their stability in nature. Here, we show that acyl-HSLs are biodegraded in soils sampled from diverse U.S. sites and by termite hindgut contents. When amended to samples at physiologically relevant concentrations, 14C-labeled acyl-HSLs were mineralized to 14CO2 rapidly and, at most sites examined, without lag. A lag-free turf soil activity was characterized in further detail. Heating or irradiation of the soil prior to the addition of radiolabel abolished mineralization, whereas protein synthesis inhibitors did not. Mineralization exhibited an apparent Km of 1.5 μM acyl-HSL, ca. 1,000-fold lower than that reported for a purified acyl-HSL lactonase. Under optimal conditions, acyl-HSL degradation proceeded at a rate of 13.4 nmol · h−1 · g of fresh weight soil−1. Bioassays established that the final extent of signal inactivation was greater than for its full conversion to CO2 but that the two processes were well coupled kinetically. A most probable number of 4.6 × 105 cells · g of turf soil−1 degraded physiologically relevant amounts of hexanoyl-[1-14C]HSL to 14CO2. It would take chemical lactonolysis months to match the level of signal decay achieved in days by the observed biological activity. Rapid decay might serve either to quiet signal cross talk that might otherwise occur between spatially separated microbial aggregates or as a full system reset. Depending on the context, biological signal decay might either promote or complicate cellular communications and the accuracy of population density-based controls on gene expression in species-rich ecosystems. PMID:15746331

Degradation of 4-aminoantipyrine by electro-oxidation with a boron-doped diamond anode: Optimization by central composite design, oxidation products and toxicity.

PubMed

de Melo da Silva, Lucas; Gozzi, Fábio; Sirés, Ignasi; Brillas, Enric; de Oliveira, Silvio Cesar; Machulek, Amilcar

2018-08-01

Electro-oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ) was applied to treat acidic aqueous solutions of 4-aminoantipyrine (4-AA), a persistent drug metabolite of dipyrone, in sulfate medium. Trials were made using a boron-doped diamond anode in the presence of H 2 O 2 electrogenerated on site. A 2 4 central composite design (CCD) was employed to evaluate the effect of four independent variables, namely current density (j), pH, 4-AA concentration and electrolysis time, on the percentages of degradation and mineralization, as well as on mineralization current efficiency (MCE). Predicted responses agreed with observed values, showing linear trendlines with good R 2 and R 2 adj values. The degradation was optimum at j=77.5mAcm -2 , pH3.5 and 62.5mgL -1 4-AA, leading to 63% and 99% removal after 3 and 7min, respectively. For those solutions, the largest mineralization was found at j=77.5mAcm -2 , attaining 45% abatement at 175min. Low MCE values were obtained in all electrolyses. An initial route for 4-AA degradation is proposed based on one dimer and eleven aromatic and aliphatic intermediates detected in the treated solutions at pH3.5 by LC-MS. The initial 62.5mgL -1 solution at pH3.5 presented acute toxicity on Artemia salina larvae, with LC 50 =13.6mgL -1 , being substantially reduced after 3 and 7min of EO-H 2 O 2 at j=77.5mAcm -2 due to the formation of less toxic derivatives. Copyright © 2018 Elsevier B.V. All rights reserved.

Reactive transport modeling of processes controlling the distribution and natural attenuation of phenolic compounds in a deep sandstone aquifer

NASA Astrophysics Data System (ADS)

Mayer, K. U.; Benner, S. G.; Frind, E. O.; Thornton, S. F.; Lerner, D. N.

2001-12-01

Reactive solute transport modeling was utilized to evaluate the potential for natural attenuation of a contaminant plume containing phenolic compounds at a chemical producer in the West Midlands, UK. The reactive transport simulations consider microbially mediated biodegradation of the phenolic compounds (phenols, cresols, and xylenols) by multiple electron acceptors. Inorganic reactions including hydrolysis, aqueous complexation, dissolution of primary minerals, formation of secondary mineral phases, and ion exchange are considered. One-dimensional (1D) and three-dimensional (3D) simulations were conducted. Mass balance calculations indicate that biodegradation in the saturated zone has degraded approximately 1-5% of the organic contaminant plume over a time period of 47 years. Simulations indicate that denitrification is the most significant degradation process, accounting for approximately 50% of the organic contaminant removal, followed by sulfate reduction and fermentation reactions, each contributing 15-20%. Aerobic respiration accounts for less than 10% of the observed contaminant removal in the saturated zone. Although concentrations of Fe(III) and Mn(IV) mineral phases are high in the aquifer sediment, reductive dissolution is limited, producing only 5% of the observed mass loss. Mass balance calculations suggest that no more than 20-25% of the observed total inorganic carbon (TIC) was generated from biodegradation reactions in the saturated zone. Simulations indicate that aerobic biodegradation in the unsaturated zone, before the contaminant entered the aquifer, may have produced the majority of the TIC observed in the plume. Because long-term degradation is limited to processes within the saturated zone, use of observed TIC concentrations to predict the future natural attenuation may overestimate contaminant degradation by a factor of 4-5.

Effects of Cu2+ and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp. strain CDT.

PubMed

Ma, Yini; Zhao, Yingying; Wang, Yongfeng; Li, Xiangzhen; Sun, Feifei; Corvini, Phillippe Francois-Xavier; Ji, Rong

2017-12-01

Soil contamination with tetrabromobisphenol A (TBBPA) has caused great concerns; however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with 14 C-labeled TBBPA for 87 days in the absence and presence of Cu 2+ and humic acids (HA). TBBPA was degraded to organic-solvent extractable (59.4%±2.2%) and non-extractable (25.1%±1.3%) metabolites, mineralized to CO 2 (4.8%±0.8%), and assimilated into cells (10.6%±0.9%) at the end of incubation. When Cu 2+ was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu 2+ to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1%±3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu 2+ and HA were both present, Cu 2+ significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu 2+ and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity. Copyright © 2017. Published by Elsevier B.V.

Anthracycline antibiotics derivate mitoxantrone-Destructive sorption and photocatalytic degradation.

PubMed

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

2018-01-01

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

Methyl t-Butyl Ether Mineralization in Surface-Water Sediment Microcosms under Denitrifying Conditions

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

2001-01-01

Mineralization of [U-14C] methyl t-butyl ether (MTBE) to 14CO2 without accumulation of t-butyl alcohol (TBA) was observed in surface-water sediment microcosms under denitrifying conditions. Methanogenic activity and limited transformation of MTBE to TBA were observed in the absence of denitrification. Results indicate that bed sediment microorganisms can effectively degrade MTBE to nontoxic products under denitrifying conditions.

Bacterial diversity in the active stage of a bioremediation system for mineral oil hydrocarbon-contaminated soils.

PubMed

Popp, Nicole; Schlömann, Michael; Mau, Margit

2006-11-01

Soils contaminated with mineral oil hydrocarbons are often cleaned in off-site bioremediation systems. In order to find out which bacteria are active during the degradation phase in such systems, the diversity of the active microflora in a degrading soil remediation system was investigated by small-subunit (SSU) rRNA analysis. Two sequential RNA extracts from one soil sample were generated by a procedure incorporating bead beating. Both extracts were analysed separately by generating individual SSU rDNA clone libraries from cDNA of the two extracts. The sequencing results showed moderate diversity. The two clone libraries were dominated by Gammaproteobacteria, especially Pseudomonas spp. Alphaproteobacteria and Betaproteobacteria were two other large groups in the clone libraries. Actinobacteria, Firmicutes, Bacteroidetes and Epsilonproteobacteria were detected in lower numbers. The obtained sequences were predominantly related to genera for which cultivated representatives have been described, but were often clustered together in the phylogenetic tree, and the sequences that were most similar were originally obtained from soils and not from pure cultures. Most of the dominant genera in the clone libraries, e.g. Pseudomonas, Acinetobacter, Sphingomonas, Acidovorax and Thiobacillus, had already been detected in (mineral oil hydrocarbon) contaminated environmental samples. The occurrence of the genera Zymomonas and Rhodoferax was novel in mineral oil hydrocarbon-contaminated soil.

Removal of artificial sweetener aspartame from aqueous media by electrochemical advanced oxidation processes.

PubMed

Lin, Heng; Oturan, Nihal; Wu, Jie; Sharma, Virender K; Zhang, Hui; Oturan, Mehmet A

2017-01-01

The degradation and mineralization of aspartame (ASP) in aqueous solution were investigated, for the first time, by electrochemical advanced oxidation processes (EAOPs) in which hydroxyl radicals were formed concomitantly in the bulk from Fenton reaction via in situ electrogenerated Fenton's reagent and at the anode surface from the water oxidation. Experiments were performed in an undivided cylindrical glass cell with a carbon-felt cathode and a Pt or boron-doped diamond (BDD) anode. The effect of Fe 2+ concentration and applied current on the degradation and mineralization kinetics of ASP was evaluated. The absolute rate constant for the reaction between ASP and OH was determined as (5.23 ± 0.02) × 10 9  M -1  s -1 by using the competition kinetic method. Almost complete mineralization of ASP was achieved with BDD anode at 200 mA constant current electrolysis. The formation and generation of the formed carboxylic acids (as ultimate end products before complete mineralization) and released inorganic ion were monitored by ion-exclusion high performance liquid chromatography (HPLC) and ion chromatography techniques, respectively. The global toxicity of the treated ASP solution during treatment was assessed by the Microtox ® method using V. fischeri bacteria luminescence inhibition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visible light photocatalytic activities of template free porous graphitic carbon nitride-BiOBr composite catalysts towards the mineralization of reactive dyes

NASA Astrophysics Data System (ADS)

Kanagaraj, Thamaraiselvi; Thiripuranthagan, Sivakumar; Paskalis, Sahaya Murphin Kumar; Abe, Hideki

2017-12-01

Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x = 5, 10, 30, 50 & 70 wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.

Photo Degradation of Methyl Orange by Persulfate Activated with Zero Valent Iron

NASA Astrophysics Data System (ADS)

Munkoeva, V. A.; Sizykh, M. R.; Batoeva, A. A.

2017-11-01

The oxidative degradation of Methyl Orange (MO) subjected to direct photolysis (Solar) and various oxidative systems was studied. The comparative experiments have shown that MO conversion and mineralization increases in the following order: Solar ∼ Solar/Fe0 ∼ Solar/S2O82- < S2O82-/Fe0 < Solar/S2O82-/Fe0. The influence of the main factors (duration of exposure, the ratio of initial concentrations of MO:S2O82-:Fe0, pH and temperature of the reaction medium) on the degree of MO conversion and mineralization was studied. The optimal pH and temperature of the reaction medium were 5.8 and 25°C, respectively. The rate of MO decomposition and mineralization increased proportionally to the initial concentration of the oxidant at the molar ratios [S2O82-] :[MO] ≤ 12. Judging by the nature of the kinetic curves, a further increase of this ratio is impractical. However, an increase in the oxidant concentration had a positive effect on the degrees of conversion and mineralization of total organic carbon (TOC). Thus, at the ratios of 12:1 and 48:1, the conversion efficiency of TOC was 23 and 60 %, respectively. The optimal concentration of Fe0 was 100 mg/l.

Impact of soil water regime on degradation and plant uptake behaviour of the herbicide isoproturon in different soil types.

PubMed

Grundmann, Sabine; Doerfler, Ulrike; Munch, Jean Charles; Ruth, Bernhard; Schroll, Reiner

2011-03-01

The environmental fate of the worldwide used herbicide isoproturon was studied in four different, undisturbed lysimeters in the temperate zone of Middle Europe. To exclude climatic effects due to location, soils were collected at different regions in southern Germany and analyzed at a lysimeter station under identical environmental conditions. (14)C-isoproturon mineralization varied between 2.59% and 57.95% in the different soils. Barley plants grown on these lysimeters accumulated (14)C-pesticide residues from soil in partially high amounts and emitted (14)CO(2) in an extent between 2.01% and 13.65% of the applied (14)C-pesticide. Plant uptake and (14)CO(2) emissions from plants were inversely linked to the mineralization of the pesticide in the various soils: High isoproturon mineralization in soil resulted in low plant uptake whereas low isoproturon mineralization in soil resulted in high uptake of isoproturon residues in crop plants and high (14)CO(2) emission from plant surfaces. The soil water regime was identified as an essential factor that regulates degradation and plant uptake of isoproturon whereby the intensity of the impact of this factor is strongly dependent on the soil type. Copyright © 2010 Elsevier Ltd. All rights reserved.

Degradation of reactive orange 4 dye using hydrodynamic cavitation based hybrid techniques.

PubMed

Gore, Mohan M; Saharan, Virendra Kumar; Pinjari, Dipak V; Chavan, Prakash V; Pandit, Aniruddha B

2014-05-01

In the present work, degradation of reactive orange 4 dye (RO4) has been investigated using hydrodynamic cavitation (HC) and in combination with other AOP's. In the hybrid techniques, combination of hydrodynamic cavitation and other oxidizing agents such as H2O2 and ozone have been used to get the enhanced degradation efficiency through HC device. The hydrodynamic cavitation was first optimized in terms of different operating parameters such as operating inlet pressure, cavitation number and pH of the operating medium to get the maximum degradation of RO4. Following the optimization of HC parameters, the degradation of RO4 was carried out using the combination of HC with H2O2 and ozone. It has been found that the efficiency of the HC can be improved significantly by combining it with H2O2 and ozone. The mineralization rate of RO4 increases considerably with 14.67% mineralization taking place using HC alone increases to 31.90% by combining it with H2O2 and further increases to 76.25% through the combination of HC and ozone. The synergetic coefficient of greater than one for the hybrid processes of HC+H2O2 and HC+Ozone has suggested that the combination of HC with other oxidizing agents is better than the individual processes for the degradation of dye effluent containing RO4. The combination of HC with ozone proves to be the most energy efficient method for the degradation of RO4 as compared to HC alone and the hybrid process of HC and H2O2. Copyright © 2013 Elsevier B.V. All rights reserved.

Polycyclic Aromatic Hydrocarbon Degradation of Phytoplankton-Associated Arenibacter spp. and Description of Arenibacter algicola sp. nov., an Aromatic Hydrocarbon-Degrading Bacterium

PubMed Central

Rhodes, Glenn; Mishamandani, Sara; Berry, David; Whitman, William B.; Nichols, Peter D.; Semple, Kirk T.; Aitken, Michael D.

2014-01-01

Pyrosequencing of the bacterial community associated with a cosmopolitan marine diatom during enrichment with crude oil revealed several Arenibacter phylotypes, of which one (OTU-202) had become significantly enriched by the oil. Since members of the genus Arenibacter have not been previously shown to degrade hydrocarbons, we attempted to isolate a representative strain of this genus in order to directly investigate its hydrocarbon-degrading potential. Based on 16S rRNA sequencing, one isolate (designated strain TG409T) exhibited >99% sequence identity to three type strains of this genus. On the basis of phenotypic and genotypic characteristics, strain TG409T represents a novel species in the genus Arenibacter, for which the name Arenibacter algicola sp. nov. is proposed. We reveal for the first time that polycyclic aromatic hydrocarbon (PAH) degradation is a shared phenotype among members of this genus, indicating that it could be used as a taxonomic marker for this genus. Kinetic data for PAH mineralization rates showed that naphthalene was preferred to phenanthrene, and its mineralization was significantly enhanced in the presence of glass wool (a surrogate for diatom cell surfaces). During enrichment on hydrocarbons, strain TG409T emulsified n-tetradecane and crude oil, and cells were found to be preferentially attached to oil droplets, indicating an ability by the strain to express cell surface amphiphilic substances (biosurfactants or bioemulsifiers) as a possible strategy to increase the bioavailability of hydrocarbons. This work adds to our growing knowledge on the diversity of bacterial genera in the ocean contributing to the degradation of oil contaminants and of hydrocarbon-degrading bacteria found living in association with marine eukaryotic phytoplankton. PMID:24212584

Simultaneous catalytic degradation of 2,4-D and MCPA herbicides using sulfate radical-based heterogeneous oxidation over persulfate activated by natural hematite (α-Fe2O3/PS)

NASA Astrophysics Data System (ADS)

Kermani, Majid; Mohammadi, Farzad; Kakavandi, Babak; Esrafili, Ali; Rostamifasih, Zeinab

2018-06-01

Herein, a sulfate radical (SO4rad -)-based oxidation process was utilized for simultaneous degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicides using mesoporous hematite-based natural semi-conductor minerals (HM-NSMs) as efficient activators of persulfate (PS). The features of the catalyst were characterized using field emission scanning electron microscopy (FESEM); Brunauer, Emmett and Teller (BET) analysis; X-ray diffraction (XRD); and energy-dispersive X-ray spectroscopy (EDS). The effect of some operational parameters, including solution pH, catalyst loading, PS dosage and temperature, on the performance system of PS/HM-NSMs was examined. A plausible oxidation mechanism for degradation of both pollutants was also proposed. Increasing the removal efficiency of herbicides follows the order of PS/HM-NSM > HM-NSM > PS. In all experiments, the 2,4-D removal rates were slightly lower than those for MCPA, indicating that 2,4-D has a more recalcitrant nature than MCPA. Under optimized conditions, degradation rates of 68.1% and 74.5% were achieved for 2,4-D and MCPA, respectively, during a 120-min reaction. HM-NSM displays a highly synergistic effect on the degradation of herbicides in the presence of PS. The trapping experiments demonstrated that both OHrad and SO4rad - radicals contribute significantly during the degradation of 2,4-D and MCPA and that sulfate radicals were the dominant species. A mineralization degree of 36% was obtained under optimum conditions. In conclusion, the coupling of PS and HM-NSM is a promising and effective technique to degrade organic matter for the treatment of herbicide-contaminated waters and wastewaters under real conditions.

Trimethoprim degradation by Fenton and Fe(II)-activated persulfate processes.

PubMed

Wang, Shizong; Wang, Jianlong

2018-01-01

Trimethoprim is a pollutant ubiquitous in the environment due to its extensive application, and it cannot be effectively removed by conventional wastewater treatment processes. In this study, the Fenton and the Fe(II)-activated persulfate processes were employed to degrade trimethoprim in an aqueous solution. The results showed that the concentration of persulfate, H 2 O 2 and Fe(II) a had significant influence on the degradation of trimethoprim in both processes. De-ionized water spiked with trimethoprim resulted in the complete degradation of trimethoprim (0.05 mM) by the mineralization of 54.9% of Fenton's reagent when the concentrations of H 2 O 2 and Fe(II) were 1 mM and 0.05 mM, respectively. In contrast, 73.4% of trimethoprim was degraded by the mineralization of 40.5% of the Fe(II)-activated persulfate process when the concentration of persulfate and Fe(II) were each 4 mM. Intermediate compounds with different m/z were detected for the Fenton and the Fe(II)-activated persulfate processes, indicating alternative degradation pathways. In the actual wastewater spiked with trimethoprim, the removal efficiency of trimethoprim decreased to 35.8% and 43.6%, respectively, for the Fenton and the Fe(II)-activated persulfate processes. In addition, the decomposition efficiencies for hydrogen peroxide and persulfate were 43.8% and 92.5%, respectively, which was lower than those in the de-ionized water system. These results demonstrated that wastewater components had a negative influence on trimethoprim degradation and the decomposition of the oxidants (persulfate and H 2 O 2 ). In summary, the Fe(II)-activated persulfate process could be used as an alternative technology for treating trimethoprim-containing wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

One-pot synthesis of metal-organic framework@SiO2 core-shell nanoparticles with enhanced visible-light photoactivity.

PubMed

Li, Zong-Qun; Wang, Ai; Guo, Chun-Yan; Tai, Yan-Fang; Qiu, Ling-Guang

2013-10-14

This paper presents a novel strategy to prepare Cu3(BTC)2@SiO2 core-shell nanoparticles in the size range of 200-400 nm using a new one-pot strategy under ultrasonic irradiation at room temperature. In this approach, the silica shell thickness could be finely tuned in the size range of 12-60 nm for various reaction times. Nanocomposite thin films were fabricated on the glass substrates by Sol-Gel spin coating using the products for 1.5 h, 2 h and 2.5 h, respectively, and heat treated using an infrared lamp heating system in air. The photocatalytic degradation of phenol in aqueous solution using Cu2(BTC)3@SiO2 thin films was investigated under visible light irradiation at pH 4. After a 45 min reaction with phenol, the degradation rate was up to 93.1%. Moreover, the thin film photocatalysts could be reused 5 times without appreciable loss of photocatalytic activity for degradation of phenol. The present work clearly shows that the films as photocatalysts showed higher photocatalytic performance.

Comparative study on the process behavior and reaction kinetics in sonocatalytic degradation of organic dyes by powder and nanotubes TiO2.

PubMed

Pang, Yean Ling; Abdullah, Ahmad Zuhairi

2012-05-01

Sonocatalytic degradation of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Rhodamine B and Methylene Blue) catalyzed by powder and nanotubes TiO(2) was studied. Both catalysts were characterized using transmission electron microscope (TEM), surface analyzer, Raman spectroscope and thermal gravimetric analyzer (TGA). Sonocatalytic activity of powder and nanotubes TiO(2) was elucidated based on the degradation of various organic dyes. The former catalyst was favorable for treatment of anionic dyes, while the latter was more beneficial for cationic dyes. Sonocatalytic activity of TiO(2) nanotubes could be up to four times as compared to TiO(2) powder under an ultrasonic power of 100 W and a frequency of 42 kHz. This was associated with the higher surface area and the electrostatic attraction between dye molecules and TiO(2) nanotubes. Fourier transform-infrared spectrometer (FT-IR) was used to identify changes that occurred on the functional group in Rhodamine B molecules and TiO(2) nanotubes after the reaction. Sonocatalytic degradation of Rhodamine B by TiO(2) nanotubes apparently followed the Langmuir-Hinshelwood adsorption kinetic model with surface reaction rate of 1.75 mg/L min. TiO(2) nanotubes were proven for their high potential to be applied in sonocatalytic degradation of organic dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Molecular preservation in Late Cretaceous sauropod dinosaur eggshells.

PubMed

Schweitzer, M H; Chiappe, L; Garrido, A C; Lowenstein, J M; Pincus, S H

2005-04-22

Exceptionally preserved sauropod eggshells discovered in Upper Cretaceous (Campanian) deposits in Patagonia, Argentina, contain skeletal remains and soft tissues of embryonic Titanosaurid dinosaurs. To preserve these labile embryonic remains, the rate of mineral precipitation must have superseded post-mortem degradative processes, resulting in virtually instantaneous mineralization of soft tissues. If so, mineralization may also have been rapid enough to retain fragments of original biomolecules in these specimens. To investigate preservation of biomolecular compounds in these well-preserved sauropod dinosaur eggshells, we applied multiple analytical techniques. Results demonstrate organic compounds and antigenic structures similar to those found in extant eggshells.

Molecular preservation in Late Cretaceous sauropod dinosaur eggshells

PubMed Central

Schweitzer, M.H; Chiappe, L; Garrido, A.C; Lowenstein, J.M; Pincus, S.H

2005-01-01

Exceptionally preserved sauropod eggshells discovered in Upper Cretaceous (Campanian) deposits in Patagonia, Argentina, contain skeletal remains and soft tissues of embryonic Titanosaurid dinosaurs. To preserve these labile embryonic remains, the rate of mineral precipitation must have superseded post-mortem degradative processes, resulting in virtually instantaneous mineralization of soft tissues. If so, mineralization may also have been rapid enough to retain fragments of original biomolecules in these specimens. To investigate preservation of biomolecular compounds in these well-preserved sauropod dinosaur eggshells, we applied multiple analytical techniques. Results demonstrate organic compounds and antigenic structures similar to those found in extant eggshells. PMID:15888409

Effect of process intensifying parameters on the hydrodynamic cavitation based degradation of commercial pesticide (methomyl) in the aqueous solution.

PubMed

Raut-Jadhav, Sunita; Saini, Daulat; Sonawane, Shirish; Pandit, Aniruddha

2016-01-01

Methomyl, a carbamate pesticide, is classified as a pesticide of category-1 toxicity and hence shows harmful effects on both human and aquatic life. In the present work, the degradation of methomyl has been studied by using hydrodynamic cavitation reactor (HC) and its combination with intensifying agents such as H2O2, fenton reagent and ozone (hybrid processes). Initially, the optimization of operating parameters such pH and inlet pressure to the cavitating device (circular venturi) has been carried out for maximizing the efficacy of hydrodynamic cavitation. Further degradation study of methomyl by the application of hybrid processes was carried out at an optimal pH of 2.5 and the optimal inlet pressure of 5 bar. Significant synergetic effect has been observed in case of all the hybrid processes studied. Synergetic coefficient of 5.8, 13.41 and 47.6 has been obtained by combining hydrodynamic cavitation with H2O2, fenton process and ozone respectively. Efficacy of individual and hybrid processes has also been obtained in terms of energy efficiency and extent of mineralization. HC+Ozone process has proved to be the most effective process having highest synergetic coefficient, energy efficiency and the extent of mineralization. The study has also encompassed the identification of intermediate by-products generated during the degradation and has proposed the probable degradation pathway. It has been conclusively established that hydrodynamic cavitation in the presence of intensifying agents can effectively be used for complete degradation of methomyl. Copyright © 2015 Elsevier B.V. All rights reserved.

Identification of concrete deteriorating minerals by polarizing and scanning electron microscopy

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

Gregerova, Miroslava, E-mail: mirka@sci.muni.cz; Vsiansky, Dalibor, E-mail: daliborv@centrum.cz

2009-07-15

The deterioration of concrete represents one of the most serious problems of civil engineering worldwide. Besides other processes, deterioration of concrete consists of sulfate attack and carbonation. Sulfate attack results in the formation of gypsum, ettringite and thaumasite in hardened concrete. Products of sulfate attack may cause a loss of material strength and a risk of collapse of the concrete constructions. The authors focused especially on the microscopical research of sulfate attack. Concrete samples were taken from the Charles Bridge in Prague, Czech Republic. A succession of degrading mineral formation was suggested. Microscope methods represent a new approach to solvingmore » the deterioration problems. They enable evaluation of the state of concrete constructions and in cooperation with hydro-geochemistry, mathematics and statistics permit prediction of the durability of a structure. Considering the number of concrete constructions and their age, research of concrete deterioration has an increasing importance. The results obtained can also be useful for future construction, because they identify the risk factors associated with formation of minerals known to degrade structures.« less

Mineralization of reactive azo dyes present in simulated textile waste water using down flow microaerophilic fixed film bioreactor.

PubMed

Balapure, Kshama; Bhatt, Nikhil; Madamwar, Datta

2015-01-01

The present research emphasizes on degradation of azo dyes from simulated textile wastewater using down flow microaerophilic fixed film reactor. Degradation of simulated textile wastewater (COD 7200mg/L and dye concentration 300mg/L) was studied in a microaerophilic fixed film reactor using pumice stone as a support material under varying hydraulic retention time (HRT) and organic loading rate (OLR). The intense metabolic activity of the inoculated bacterial consortium in the reactor led to 97.5% COD reduction and 99.5% decolorization of simulated wastewater operated under OLR of 7.2kgCODm(3)/d and 24h of HRT. FTIR, (1)H NMR and GC-MS studies revealed the formation of lower molecular weight aliphatic compounds under 24h of HRT, leading to complete mineralization of simulated wastewater. The detection of oxido-reductive enzyme activities suggested the enzymatic reduction of azo bonds prior to mineralization. Toxicity studies indicated that microbial treatment favors detoxification of simulated wastewater. Copyright © 2014 Elsevier Ltd. All rights reserved.

Compressible and Recyclable Monolithic g-C3N4/Melamine Sponge: A Facile Ultrasonic-coating Approach and Enhanced Visible-light Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Yang, Ye; Zhang, Qian; Zhang, Ruiyang; Ran, Tao; Wan, Wenchao; Zhou, Ying

2018-05-01

Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C3N4/melamine sponge (g-C3N4/MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C3N4 on MS skeleton. The monolithic g-C3N4/MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C3N4/MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal, rhodamine B (RhB) degradation and CO2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C3N4, while RhB degradation rate reaches 97.88%, and yield rate of CO and CH4 attains 7.48 and 3.93 μmol g-1 h-1. Importantly, the features of low-density, high porosity, good elasticity and firmness, not only endow g-C3N4/MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.

Improving anaerobic and aerobic degradation by ultrasonic disintegration of biomass.

PubMed

Neis, Uwe; Nickel, Klaus; Lundén, Anna

2008-11-01

Biological cell lysis is known to be the rate-limiting step of anaerobic biosolids degradation. Due to the slow pace by which this reaction occurs, it is necessary to equip treatment plants with large digesters or alternatively incorporate technological aids. High-power ultrasound used to disintegrate bacterial cells has been utilized as a pre-treatment process prior to anaerobic digestion. Through this application, as seen on pilot- and full-scales, it is possible to attain up to 30% more biogas, an increase in VS-destruction of up to 30% and a reduced sludge mass for disposal. Utilizing ultrasound technology in aerobic applications is a new and innovative approach. Improved denitrification through a more readily available internal carbon source, and less excess sludge mass can be traced to the positive effects that sonication of sludge has on the overall biological wastewater treatment process. Reference full-scale installations suggest that the technology is both technically feasible and economically sound.

Preparation of zeolite nanorods by corona discharge plasma for degradation of phenazopyridine by heterogeneous sono-Fenton-like process.

PubMed

Khataee, Alireza; Rad, Tannaz Sadeghi; Vahid, Behrouz; Khorram, Sirous

2016-11-01

The plasma-modified clinoptilolite (PMC) nanorods were prepared from natural clinoptilolite (NC) utilizing environmentally-friendly corona discharge plasma. The PMC and NC were characterized by XRD, FT-IR, SEM, EDX, XPS and BET, which confirmed the nanocatalyst formation. The catalytic performance of the PMC in the heterogeneous sono-Fenton-like process was greater than the NC for treatment of phenazopyridine (PhP). The desired amounts were obtained for experimental parameters including initial pH (5), PMC dosage (2g/L), K2S2O8 concentration (2mmol/L), ultrasonic power (300W) and PhP concentration (10mg/L). Reactive oxygen species scavengers decreased the removal efficiency of the PhP. The treatment process followed pseudo-first order kinetic and seven degradation intermediates were identified by the GC-MS technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of photocalalytic activity of ZnO prepared by spray pyrolis with various precursors

NASA Astrophysics Data System (ADS)

Bourfaa, F.; Lamri Zeggar, M.; A, A.; Aida, M. S.; Attaf, N.

2016-03-01

Semiconductor photocatalysts such as ZnO has attracted much attention in recent years due to their various applications for the degradation of organic pollutants in water, air and in dye sensitized photovoltaic solar cell. In the present work, ZnO thin films were prepared by ultrasonic spray pyrolysis by using different precursors namely: acetate, chloride and zinc nitrate in order to investigate their influence on ZnO photocatalytic activity. The films crystalline structure was studied by mean of X- ray diffraction measurements (XRD) and the films surface morphology by Scanning Electron Microscopy (SEM). The films optical properties were studied by mean of UV-visible spectroscopy. The prepared films were tested for the degradation of the red reactive dye largely used in textile industry. As a result, we found that the zinc nitrate is the best precursor to prepare ZnO thin films suitable for a good photocatalytic activity.

Reaction of bone nanostructure to a biodegrading Magnesium WZ21 implant - A scanning small-angle X-ray scattering time study.

PubMed

Grünewald, T A; Ogier, A; Akbarzadeh, J; Meischel, M; Peterlik, H; Stanzl-Tschegg, S; Löffler, J F; Weinberg, A M; Lichtenegger, H C

2016-02-01

Understanding the implant-bone interaction is of prime interest for the development of novel biodegrading implants. Magnesium is a very promising material in the class of biodegrading metallic implants, owing to its mechanical properties and excellent immunologic response during healing. However, the influence of degrading Mg implants on the bone nanostructure is still an open question of crucial importance for the design of novel Mg implant alloys. This study investigates the changes in the nanostructure of bone following the application of a degrading WZ21 Mg implant (2wt% Y, 1wt% Zn, 0.25wt% Ca and 0.15wt% Mn) in a murine model system over the course of 15months by small angle X-ray scattering. Our investigations showed a direct response of the bone nanostructure after as little as 1month with a realignment of nano-sized bone mineral platelets along the bone-implant interface. The growth of new bone tissue after implant resorption is characterized by zones of lower mineral platelet thickness and slightly decreased order in the stacking of the platelets. The preferential orientation of the mineral platelets strongly deviates from the normal orientation along the shaft and still roughly follows the implant direction after 15months. We explain our findings by considering geometrical, mechanical and chemical factors during the process of implant resorption. The advancement of surgical techniques and the increased life expectancy have caused a growing demand for improved bone implants. Ideally, they should be bio-resorbable, support bone as long as necessary and then be replaced by healthy bone tissue. Magnesium is a promising candidate for this purpose. Various studies have demonstrated its excellent mechanical performance, degradation behaviour and immunologic properties. The structural response of bone, however, is not well known. On the nanometer scale, the arrangement of collagen fibers and calcium mineral platelets is an important indicator of structural integrity. The present study provides insight into nanostructural changes in rat bone at different times after implant placement and different implant degradation states. The results are useful for further improved magnesium alloys. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Analysis of glyphosate degradation in a soil microcosm.

PubMed

la Cecilia, Daniele; Maggi, Federico

2018-02-01

Glyphosate (GLP) herbicide leaching into soil can undergo abiotic degradation and two enzymatic oxidative or hydrolytic reactions in both aerobic and anaerobic conditions; biotic oxidation produces aminomethylphosphonic acid (AMPA). Both GLP and AMPA are phytotoxic. A comprehensive GLP degradation reaction network was developed from the literature to account for the above pathways, and fifteen experimental data sets were used to determine the corresponding Michaelis-Menten-Monod (MMM) kinetic parameters. Various sensitivity analyses were designed to assess GLP and AMPA degradation potential against O 2 (aq) and carbon (C) availability, pH, and birnessite mineral content, and showed that bacteria oxidized or hydrolyzed up to 98% of GLP and only 9% of AMPA. Lack of a C source limited the GLP cometabolic hydrolytic pathways, which produces non-toxic byproducts and promotes AMPA biodegradation. Low bacterial activity in O 2 (aq)-limited conditions or non-neutral pH resulted in GLP accumulation. Birnessite mineral catalyzed fast GLP and AMPA chemodegradation reaching alone efficiencies of 79% and 88%, respectively, regardless of the other variables and produced non-toxic byproducts. Overall, O 2 (aq) and birnessite availability played the major roles in determining the partitioning of GLP and its byproducts mass fluxes across the reaction network, while birnessite, C availability, and pH affected GLP and AMPA biodegradation effectiveness. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nanostructured ZnO-TiO2 thin film oxide as anode material in electrooxidation of organic pollutants. Application to the removal of dye Amido black 10B from water.

PubMed

El-Kacemi, Sana; Zazou, Hicham; Oturan, Nihal; Dietze, Matthias; Hamdani, Mohamed; Es-Souni, Mohammed; Oturan, Mehmet A

2017-01-01

Electrochemical oxidative degradation of diazo dye Amido black 10B (AB10B) as model pollutant in water has been studied using nanostructured ZnO-TiO 2 thin films deposited on graphite felt (GrF) substrate as anode. The influence of various operating parameters, namely the current intensity, the nature and concentration of catalyst, the nature of electrode materials (anode/cathode), and the adsorption of dye and ambient light were investigated. It was found that the oxidative degradation of AB10B followed pseudo first-order kinetics. The optimal operating conditions for the degradation of 0.12 mM (74 mg L -1 ) dye concentration and mineralization of its aqueous solution were determined as GrF-ZnO-TiO 2 thin film anode, 100 mA current intensity, and 0.1 mM Fe 2+ (catalyst) concentration. Under these operating conditions, discoloration of AB10B solution was reached at 60 min while 6 h treatment needed for a mineralization degree of 91 %. Therefore, this study confirmed that the electrochemical process is effective for the degradation of AB10B in water using nanostructured ZnO-TiO 2 thin film anodes.

Pulsed (13)C2-Acetate Protein-SIP Unveils Epsilonproteobacteria as Dominant Acetate Utilizers in a Sulfate-Reducing Microbial Community Mineralizing Benzene.

PubMed

Starke, Robert; Keller, Andreas; Jehmlich, Nico; Vogt, Carsten; Richnow, Hans H; Kleinsteuber, Sabine; von Bergen, Martin; Seifert, Jana

2016-05-01

In a benzene-degrading and sulfate-reducing syntrophic consortium, a clostridium affiliated to the genus Pelotomaculum was previously described to ferment benzene while various sulfate-reducing Deltaproteobacteria and a member of the Epsilonproteobacteria were supposed to utilize acetate and hydrogen as key metabolites derived from benzene fermentation. However, the acetate utilization network within this community was not yet unveiled. In this study, we performed a pulsed (13)C2-acetate protein stable isotope probing (protein-SIP) approach continuously spiking low amounts of acetate (10 μM per day) in addition to the ongoing mineralization of unlabeled benzene. Metaproteomics revealed high abundances of Clostridiales followed by Syntrophobacterales, Desulfobacterales, Desulfuromonadales, Desulfovibrionales, Archaeoglobales, and Campylobacterales. Pulsed acetate protein-SIP results indicated that members of the Campylobacterales, the Syntrophobacterales, the Archaeoglobales, the Clostridiales, and the Desulfobacterales were linked to acetate utilization in descending abundance. The Campylobacterales revealed the fastest and highest (13)C incorporation. Previous experiments suggested that the activity of the Campylobacterales was not essential for anaerobic benzene degradation in the investigated community. However, these organisms were consistently detected in various hydrocarbon-degrading and sulfate-reducing consortia enriched from the same aquifer. Here, we demonstrate that this member of the Campylobacterales is the dominant acetate utilizer in the benzene-degrading microbial consortium.

Split-spectrum processing technique for SNR enhancement of ultrasonic guided wave.

PubMed

Pedram, Seyed Kamran; Fateri, Sina; Gan, Lu; Haig, Alex; Thornicroft, Keith

2018-02-01

Ultrasonic guided wave (UGW) systems are broadly used in several branches of industry where the structural integrity is of concern. In those systems, signal interpretation can often be challenging due to the multi-modal and dispersive propagation of UGWs. This results in degradation of the signals in terms of signal-to-noise ratio (SNR) and spatial resolution. This paper employs the split-spectrum processing (SSP) technique in order to enhance the SNR and spatial resolution of UGW signals using the optimized filter bank parameters in real time scenario for pipe inspection. SSP technique has already been developed for other applications such as conventional ultrasonic testing for SNR enhancement. In this work, an investigation is provided to clarify the sensitivity of SSP performance to the filter bank parameter values for UGWs such as processing bandwidth, filter bandwidth, filter separation and a number of filters. As a result, the optimum values are estimated to significantly improve the SNR and spatial resolution of UGWs. The proposed method is synthetically and experimentally compared with conventional approaches employing different SSP recombination algorithms. The Polarity Thresholding (PT) and PT with Minimization (PTM) algorithms were found to be the best recombination algorithms. They substantially improved the SNR up to 36.9dB and 38.9dB respectively. The outcome of the work presented in this paper paves the way to enhance the reliability of UGW inspections. Copyright © 2017 Elsevier B.V. All rights reserved.

A systematic study of mechanical properties, corrosion behavior and biocompatibility of AZ31B Mg alloy after ultrasonic nanocrystal surface modification.

PubMed

Hou, Xiaoning; Qin, Haifeng; Gao, Hongyu; Mankoci, Steven; Zhang, Ruixia; Zhou, Xianfeng; Ren, Zhencheng; Doll, Gary L; Martini, Ashlie; Sahai, Nita; Dong, Yalin; Ye, Chang

2017-09-01

Magnesium alloys have tremendous potential for biomedical applications due to their good biocompatibility, osteoconductivity, and degradability, but can be limited by their poor mechanical properties and fast corrosion in the physiological environment. In this study, ultrasonic nanocrystal surface modification (UNSM), a recently developed surface processing technique that utilizes ultrasonic impacts to induce plastic strain on metal surfaces, was applied to an AZ31B magnesium (Mg) alloy. The mechanical properties, corrosion resistance, and biocompatibility of the alloy after UNSM treatment were studied systematically. Significant improvement in hardness, yield stress and wear resistance was achieved after the UNSM treatment. In addition, the corrosion behavior of UNSM-treated AZ31B was not compromised compared with the untreated samples, as demonstrated by the weight loss and released element concentrations of Mg and Al after immersion in alpha-minimum essential medium (α-MEM) for 24h. The in vitro biocompatibility of the AZ31B Mg alloys toward adipose-derived stem cells (ADSCs) before and after UNSM processing was also evaluated using a cell culture study. Comparable cell attachments were achieved between the two groups. These studies showed that UNSM could significantly improve the mechanical properties of Mg alloys without compromising their corrosion rate and biocompatibility in vitro. These findings suggest that UNSM is a promising method to treat biodegradable Mg alloys for orthopaedic applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancement of mass transfer by ultrasound: Application to adsorbent regeneration and food drying/dehydration.

PubMed

Yao, Ye

2016-07-01

The physical mechanisms of heat and mass transfer enhancement by ultrasound have been identified by people. Basically, the effect of 'cavitation' induced by ultrasound is the main reason for the enhancement of heat and mass transfer in a liquid environment, and the acoustic streaming and vibration are the main reasons for that in a gaseous environment. The adsorbent regeneration and food drying/dehydration are typical heat and mass transfer process, and the intensification of the two processes by ultrasound is of complete feasibility. This paper makes an overview on recent studies regarding applications of power ultrasound to adsorbent regeneration and food drying/dehydration. The concerned adsorbents include desiccant materials (typically like silica gel) for air dehumidification and other ones (typically active carbon and polymeric resin) for water treatment. The applications of ultrasound in the regeneration of these adsorbents have been proved to be energy saving. The concerned foods are mostly fruits and vegetables. Although the ultrasonic treatment may cause food degradation or nutrient loss, it can greatly reduce the food processing time and decrease drying temperature. From the literature, it can be seen that the ultrasonic conditions (i.e., acoustic frequency and power levels) are always focused on during the study of ultrasonic applications. The increasing number of relevant studies argues that ultrasound is a very promising technology applied to the adsorbent regeneration and food drying/dehydration. Copyright © 2016 Elsevier B.V. All rights reserved.

Compensating temperature-induced ultrasonic phase and amplitude changes

NASA Astrophysics Data System (ADS)

Gong, Peng; Hay, Thomas R.; Greve, David W.; Junker, Warren R.; Oppenheim, Irving J.

2016-04-01

In ultrasonic structural health monitoring (SHM), environmental and operational conditions, especially temperature, can significantly affect the propagation of ultrasonic waves and thus degrade damage detection. Typically, temperature effects are compensated using optimal baseline selection (OBS) or optimal signal stretch (OSS). The OSS method achieves compensation by adjusting phase shifts caused by temperature, but it does not fully compensate phase shifts and it does not compensate for accompanying signal amplitude changes. In this paper, we develop a new temperature compensation strategy to address both phase shifts and amplitude changes. In this strategy, OSS is first used to compensate some of the phase shifts and to quantify the temperature effects by stretching factors. Based on stretching factors, empirical adjusting factors for a damage indicator are then applied to compensate for the temperature induced remaining phase shifts and amplitude changes. The empirical adjusting factors can be trained from baseline data with temperature variations in the absence of incremental damage. We applied this temperature compensation approach to detect volume loss in a thick wall aluminum tube with multiple damage levels and temperature variations. Our specimen is a thick-walled short tube, with dimensions closely comparable to the outlet region of a frac iron elbow where flow-induced erosion produces the volume loss that governs the service life of that component, and our experimental sequence simulates the erosion process by removing material in small damage steps. Our results show that damage detection is greatly improved when this new temperature compensation strategy, termed modified-OSS, is implemented.

Read-across of ready biodegradability based on the substrate specificity of N-alkyl polypropylene polyamine-degrading microorganisms.

PubMed

Geerts, R; van Ginkel, C G; Plugge, C M

2017-04-01

The biodegradation of N-alkyl polypropylene polyamines (NAPPs) was studied using pure and mixed cultures to enable read-across of ready biodegradability test results. Two Pseudomonas spp. were isolated from activated sludge with N-oleyl alkyl propylene diamine and N-coco alkyl dipropylene triamine, respectively. Both strains utilized all NAPPs tested as the sole source of carbon, nitrogen and energy for growth. Mineralization of NAPPs was independent of the alkyl chain length and the size of the polyamine moiety. NAPPs degraded in closed bottle tests (CBTs) using both river water and activated sludge. However, ready biodegradability of NAPPs with alkyl chain lengths of 16-18 carbon atoms and polyamine moieties with three and four nitrogen atoms could not be demonstrated. Biodegradation in the CBT was hampered by their limited bioavailability, making assessment of the true ready biodegradability of these highly adsorptive surfactants impossible. All NAPPs are therefore classified as readily biodegradable through read-across. Read-across is justified by the broad substrate specificity of NAPP-degrading microorganisms, their omnipresence and the mineralization of NAPPs.

Microbial Degradation of Petroleum Hydrocarbon Contaminants: An Overview

PubMed Central

Das, Nilanjana; Chandran, Preethy

2011-01-01

One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon components have been known to belong to the family of carcinogens and neurotoxic organic pollutants. Currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive when amounts of contaminants are large. Mechanical and chemical methods generally used to remove hydrocarbons from contaminated sites have limited effectiveness and can be expensive. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Bioremediation functions basically on biodegradation, which may refer to complete mineralization of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein or transformation of complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. This paper presents an updated overview of petroleum hydrocarbon degradation by microorganisms under different ecosystems. PMID:21350672

Protein enrichment of corn cob heteroxylan waste slurry by thermophilic aerobic digestion using Bacillus stearothermophilus.

PubMed

Ugwuanyi, J Obeta; Harvey, Linda M; McNeil, Brian

2008-10-01

Thermophilic aerobic digestion (TAD) of heteroxylan waste was implemented at waste load of 30gL(-1) with mineral nitrogen supplementation to study effect of the process on waste degradation, protein accretion and quality. Digestions were carried out at 45 50, 55, 60 and 65 degrees C using Bacillusstearothermophilus in a CSTR under batch conditions at 1.0vvm aeration rate, pH 7.0 for a maximum of 120h. Amylase and xylanase activities appeared rapidly in the digest, while basal protease activity appeared early in the digestion and increased towards end of the processes. Highest degradation of volatile suspended solid, hemicellulose and fibre occurred at 55 degrees C while highest degradation of total suspended solid occurred at 60 degrees C. Highest protein accretion (258.8%) and assimilation of mineral nitrogen and soluble protein occurred at 55 degrees C. The % content of amino acids of digest crude protein increased relative to raw waste and with digestion temperature. Quality of digest protein was comparable to the FAO standard for feed use. TAD has potentials for use in the protein enrichment of waste.

Adsorption of phenanthrene on activated carbon increases mineralization rate by specific bacteria.

PubMed

Leglize, Pierre; Alain, Saada; Jacques, Berthelin; Corinne, Leyval

2008-03-01

Bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil is affected by PAH sorption to solid phase. We studied the influence of activated carbon (AC) on phenanthrene (PHE) mineralization by five degrading bacterial strains isolated from contaminated soil. PHE adsorption on AC was important and reduced PHE aqueous concentration up to 90%. PHE degradation was improved in the presence of activated carbon with three of the bacterial strains, named NAH1, MATE3 and MATE7, which produced biofilms, whereas it was not improved with the two other ones, which did not produce biofilms, MATE10 and MATE12. Monitoring PHE distribution during incubation showed that aqueous PHE concentration was significantly higher with the biofilm-producing NAH1 than with MATE10. Bacterial adhesion on AC was also investigated. The precoating of AC with PHE increased NAH1 and MATE3 adhesion to the solid surface (>16 and >13%, respectively). Bacterial properties, such as biofilm production and adhesion to AC capacity seemed to be related to their ability to optimize PHE degradation by improving PHE diffusion and reducing diffusion path length.

Degradation of azo dyes by environmental microorganisms and helminths

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

Kingthom Chung; Stevens, S.E. Jr.

1993-11-01

The degradation of azo dyes by environmental microorganisms, fungi, and helminths is reviewed. Azo dyes are used in a wide variety of products and can be found in the effluent of most sewage treatment facilities. Substantial quantities of these dyes have been deposited in the environment, particularly in streams and rivers. Azo dyes were shown to affect microbial activities and microbial population sizes in the sediments and in the water columns of aquatic habitats. Only a few aerobic bacteria have been found to reduce azo dyes under aerobic conditions, and little is known about the process. A substantial number ofmore » anaerobic bacteria capable of azo dye reduction have been reported. The enzyme responsible for azo dye reduction has been partially purified, and characterization of the enzyme is proceeding. The nematode Ascaris lumbricoides and the cestode Moniezia expanza have been reported to reduce azo dyes anaerobically. Recently the fungus Phanerochaete chrysoporium was reported to mineralize azo dyes via a peroxidation-mediated pathway. A possible degradation pathway for the mineralization of azo dye is proposed and future research needs are discussed.« less

Degradation of paracetamol in aqueous solutions by TiO2 photocatalysis.

PubMed

Yang, Liming; Yu, Liya E; Ray, Madhumita B

2008-07-01

In this study, photo/photocatalytic oxidation of common analgesic and antipyretic drug, paracetamol (acetaminophen), was investigated to determine the optimal operating conditions for degradation in water. UVA (365 nm) radiation alone degraded negligible amount of paracetamol, whereas paracetamol concentration decreased substantially under an irradiation of UVC (254 nm) with marginal changes in total organic carbon (TOC). In the presence of TiO2, much faster photodegradation of paracetamol and effective mineralization occurred; more than 95% of 2.0mM paracetamol was degraded within 80 min. The degradation rate constant decreased with an increase in the initial concentration of paracetamol, while it increased with light intensity and oxygen concentration. The degradation rate also increased with TiO2 loading until a concentration of 0.8 g L(-1). The degradation rate slowly increased between pH 3.5 and 9.5, but significantly decreased with increasing pH between 9.5 and 11.0. Based on the experimental data, a kinetic equation describing paracetamol photocatalytic degradation with various process parameters is obtained.

Reinforcement of poly(amide-imide) containing N-trimellitylimido-L-phenylalanine by using nano α-Al2O3 surface-coupled with bromo-flame retardant under ultrasonic irradiation technique

NASA Astrophysics Data System (ADS)

Mallakpour, Shadpour; Khadem, Elham

2014-10-01

By the uniform dispersion of nanoparticles into a polymer matrix, a substantial improvement of physicochemical properties can be attained. In this study, a series of poly(amide-imide)/Al2O3 nanocomposites (PANC)s based on various amounts of modified α-Al2O3 nanoparticles (ANP)s were prepared using the ultrasonic irradiation method. In the process of manufacturing the nanocomposites (NC)s, severe agglomeration of ANPs into the polymer matrix can be reduced using 2,3,4,5-tetrabromo-6-[(4-hydroxyphenyl)carbamoyl]benzoic acid as novel coupling agent. The effects of modified ANPs on the morphology and properties of the polymer matrix were studied by means of Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermal gravimetric analysis (TGA). The results obtained by TGA showed that the thermal stability of the NCs was improved with the addition of the small amounts of ANPs as effective thermal degradation resistant reinforcement.

A Study of the Potential to Detect Caries Lesions at the White-Spot Stage Using V(Z) Technique

NASA Astrophysics Data System (ADS)

Bakulin, E. Y.; Denisova, L. A.; Maev, R. Gr.

Current wide-spread methods of non-destructive methods of caries diagnostics, such as X-ray techniques, do not provide the possibility to efficiently detect enamel caries lesions at the beginning ("white-spot") stage, when the tooth tissue is only slightly altered and no loss of the tissue occurs. Therefore, it is of paramount importance to develop new, more sensitive methods of caries diagnostics. In this paper, certain aspects of the ultrasonic approach to the problem are discussed - in particular, detection of the enamel's surface caries at the white-spot stage with a focused ultrasonic sensor positioned in front of the caries lesion (without cross-sectioning the tooth). Theoretical model using V(z) approach for layered media was applied to perform computer simulations resulting in V(z) curves for the different parameters of carious tissue and the degree of degradation. The curves were analyzed and it was shown that, comparing to a short-pulse/echo technique, V(z) approach provides much better distinction between sound and carious enamel and even makes possible to evaluate the degree of demineralization.

Effect of the ultrasound-Fenton oxidation process with the addition of a chelating agent on the removal of petroleum-based contaminants from soil.

PubMed

Li, Ying; Li, Fangmin; Li, Fanxiu; Yuan, Fuqian; Wei, Pingfang

2015-12-01

The effects of ultrasonic irradiation, the chelating agent modified Fenton reaction, and a combination of ultrasound and the Fenton method in removing petroleum contaminants from a soil were studied. The results showed that the contaminant removal rate of the Fenton treatment combined with an oxalic acid chelating agent was 55.6% higher than that without a chelating agent. The average removal rate of the contaminants using the ultrasound-Fenton treatment was 59.0% higher than that without ultrasonic treatment. A combination of ultrasound and an Fe(2+)/Fe(3+)-oxalate complex-modified Fenton reagent resulted in significantly higher removal rates of n-alkanes (C(n)H(2n+2), n < 28), isoprenoid hydrocarbons, aromatic hydrocarbons, and saturated polycyclic terpenes compared with the ultrasound treatment alone or the Fenton method. The Fenton reaction and the ultrasound-Fenton treatment can unselectively remove multiple components of residual hydrocarbons and a number of benzene rings in polycyclic aromatic hydrocarbons. The chemistry of the heterocyclic compounds and the position and number of substituents can affect the degradation process.

Ultrasonic chemical synthesis of CdS-reduced graphene oxide nanocomposites with an enhanced visible light photoactivity

NASA Astrophysics Data System (ADS)

Lin, Yi-Chen; Tsai, Du-Cheng; Chang, Zue-Chin; Shieu, Fuh-Sheng

2018-05-01

In this study, we report a facile ultrasonic method to prepare a series of CdS and reduced graphene oxide (CdS/rGO) composites with different weight ratios of graphene at temperature as low as 70 °C for 20 min by employing ammonia as a complexing agent of Cd2+ ions and reducing agent of graphene oxide (GO). Pure CdS particles had a poor crystallinity and aggregated to large particles size. As GO was incorporated into CdS, a uniform dispersion of CdS particles with high crystallinity on rGO sheets was clearly observed. The as-prepared CdS/rGO composites have a wide and strong photo absorption in the visible region and display a substantially improved photocatalytic activity for the degradation of methylene blue under visible light irradiation by forming a heterojunction of rGO and CdS. However, too much rGO will shield the light of the active sites for the CdS nanoparticle surface and thus limit further improvement in the photocatalytic efficiency.

Corrosion monitoring using high-frequency guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Fromme, Paul

2014-02-01

Corrosion develops due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, guided wave modes were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted and the wall thickness reduced by consecutive milling of the steel structure. Further measurements were conducted using accelerated corrosion in a salt water bath and the damage severity monitored. From the measured signal change due to the wave mode interference the wall thickness reduction was monitored. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.