Degradation of CMOS image sensors in deep-submicron technology due to γ-irradiation

NASA Astrophysics Data System (ADS)

Rao, Padmakumar R.; Wang, Xinyang; Theuwissen, Albert J. P.

2008-09-01

In this work, radiation induced damage mechanisms in deep submicron technology is resolved using finger gated-diodes (FGDs) as a radiation sensitive tool. It is found that these structures are simple yet efficient structures to resolve radiation induced damage in advanced CMOS processes. The degradation of the CMOS image sensors in deep-submicron technology due to γ-ray irradiation is studied by developing a model for the spectral response of the sensor and also by the dark-signal degradation as a function of STI (shallow-trench isolation) parameters. It is found that threshold shifts in the gate-oxide/silicon interface as well as minority carrier life-time variations in the silicon bulk are minimal. The top-layer material properties and the photodiode Si-SiO2 interface quality are degraded due to γ-ray irradiation. Results further suggest that p-well passivated structures are inevitable for radiation-hard designs. It was found that high electrical fields in submicron technologies pose a threat to high quality imaging in harsh environments.

Quantification of holmium:YAG optical tip degradation

NASA Astrophysics Data System (ADS)

Mues, Adam C.; Teichman, Joel M. H.; Knudsen, Bodo E.

2009-02-01

The holmium:yttrium aluminum garnet (YAG) laser is the gold standard laser for intracorporeal lithotripsy. Optical fibers are utilized to transmit laser energy to the surface of a stone for fragmentation. During lithotripsy, fiber tip degradation (burn back) can occur. The exact mechanism for tip degradation and related factors are not completely understood, and have not been investigated. This characteristic is important because fiber burn back may affect diminish fragmentation efficiency, increase operative time, and increase cost due to the need for fiber replacement. We hypothesize that fiber tip degradation (burn back) varies amongst different commercially available holmium:YAG laser fibers.

Advanced Oxidation of Tartrazine and Brilliant Blue with Pulsed Ultraviolet Light Emitting Diodes

PubMed Central

Scott, Robert; Mudimbi, Patrick; Miller, Michael E.; Magnuson, Matthew; Willison, Stuart; Phillips, Rebecca; Harper, Willie F.

2018-01-01

This study investigated the effect of ultraviolet light-emitting diodes (UVLEDs) coupled with hydrogen peroxide as an advanced oxidation process (AOP) for the degradation of two test chemicals. Brilliant Blue FCF consistently exhibited greater degradation than tartrazine, with 83% degradation after 300 minutes at the 100% duty cycle compared with only 17% degradation of tartrazine under the same conditions. These differences are attributable to the structural properties of the compounds. Duty cycle was positively correlated with the first-order rate constants (k) for both chemicals but, interestingly, negatively correlated with the normalized first-order rate constants (k/duty cycle). Synergistic effects of both hydraulic mixing and LED duty cycle were manifested as novel oscillations in the effluent contaminant concentration. Further, LED output and efficiency were dependent upon duty cycle and less efficient over time perhaps due to heating effects on semiconductor performance. PMID:28236826

Degradation of organic pollutants by Vacuum-Ultraviolet (VUV): Kinetic model and efficiency.

PubMed

Xie, Pengchao; Yue, Siyang; Ding, Jiaqi; Wan, Ying; Li, Xuchun; Ma, Jun; Wang, Zongping

2018-04-15

Vacuum-Ultraviolet (VUV), an efficient and green method to produce hydroxyl radical (•OH), is effective in degrading numerous organic contaminants in aqueous solution. Here, we proposed an effective and simple kinetic model to describe the degradation of organic pollutants in VUV system, by taking the •OH scavenging effects of formed organic intermediates as co-existing organic matter in whole. Using benzoic acid (BA) as a •OH probe, •OH was regarded vital for pollutant degradation in VUV system, and the thus developed model successfully predicted its degradation kinetics under different conditions. Effects of typical influencing factors such as BA concentrations and UV intensity were investigated quantitatively by the model. Temperature was found to be an important influencing factor in the VUV system, and the quantum yield of •OH showed a positive linear dependence on temperature. Impacts of humic acid (HA), alkalinity, chloride, and water matrices (realistic waters) on the oxidation efficiency were also examined. BA degradation was significantly inhibited by HA due to its scavenging of •OH, but was influenced much less by the alkalinity and chloride; high oxidation efficiency was still obtained in the realistic water. The degradation kinetics of three other typical micropollutants including bisphenol A (BPA), nitrobenzene (NB) and dimethyl phthalate (DMP), and the mixture of co-existing BA, BPA and DMP were further studied, and the developed model predicted the experimental data well, especially in realistic water. It is expected that this study will provide an effective approach to predict the degradation of organic micropollutants by the promising VUV system, and broaden the application of VUV system in water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Magnetic multi-metal co-doped magnesium ferrite nanoparticles: An efficient visible light-assisted heterogeneous Fenton-like catalyst synthesized from saprolite laterite ore.

PubMed

Diao, Yifei; Yan, Zhikai; Guo, Min; Wang, Xidong

2018-02-15

Magnetic nanoparticles of multi-metal co-doped magnesium ferrite (MgFe 2 O 4 ) were synthesized from saprolite laterite ore by a hydrothermal method, and firstly proposed as a heterogeneous photon-Fenton-like catalyst for degradation of Rhodamine B (RhB). The factors that influence the degradation reaction including pH value, the concentration of H 2 O 2 and the amount of catalyst, were systematically investigated. The doped MgFe 2 O 4 exhibited a degradation efficiency up to 96.8%, and the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies about 85.6% and 68.3%, respectively, under visible light illumination for 180min. The high activity is mainly attributed to the high specific surface area of the catalyst and the synergistic interaction between photo-catalytic oxidation and Fenton-like oxidation. Moreover, the catalyst also showed good stability and recycling performance for degrading RhB. After five consecutive degradation cycles, the activity decayed no more than 10%. Compared to other catalysts prepared from pure chemical agents, the multi-metal co-doped MgFe 2 O 4 is more competitive due to its high activity, good stability, ease of recollection, and especially the use of saprolite laterite ore as precursor. This work may provide a new avenue to synthesize efficient ferrite catalysts for degrading organic pollutants in wastewater by using natural minerals. Copyright © 2017 Elsevier B.V. All rights reserved.

Catalytic degradation of picric acid by heterogeneous Fenton-based processes.

PubMed

Dulova, Niina; Trapido, Marina; Dulov, Aleksandr

2011-01-01

The efficiency of goethite, magnetite and iron powder (Fe0) in catalysing the Fenton-based oxidation of picric acid (PA) in aqueous solution was studied. The effect of pH, hydrogen peroxide concentration, and catalyst type and dosage on treatment efficacy was investigated. The adsorption of PA from aqueous solution by heterogeneous catalysts was also examined. The results demonstrated negligible PA removal in H2O2/alpha-FeOOH and H2O2/Fe3O4 systems independent of process pH, and hydrogen peroxide and catalyst dosage. The PA adsorption effects of both iron oxides turned out to be insignificant for all studied pH values and catalyst dosages. The H2O2/Fe0 system proved efficient at degrading PA, but only under acidic conditions (pH 3). The results indicated that, due to rather fast leaching of ferrous ions from the iron powder surface, PA degradation was carried out mainly by the classic Fenton oxidation mechanism in the bulk solution. The adsorption of PA onto the iron powder surface may also contribute to the overall efficiency of PA degradation.

Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods.

PubMed

Al-Sabahi, Jamal; Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

2017-01-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products.

Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods

PubMed Central

Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

2017-01-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products. PMID:29261711

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.

Preventing light-induced degradation in multicrystalline silicon

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

Lindroos, J., E-mail: jeanette.lindroos@aalto.fi; Boulfrad, Y.; Yli-Koski, M.

2014-04-21

Multicrystalline silicon (mc-Si) is currently dominating the silicon solar cell market due to low ingot costs, but its efficiency is limited by transition metals, extended defects, and light-induced degradation (LID). LID is traditionally associated with a boron-oxygen complex, but the origin of the degradation in the top of the commercial mc-Si brick is revealed to be interstitial copper. We demonstrate that both a large negative corona charge and an aluminum oxide thin film with a built-in negative charge decrease the interstitial copper concentration in the bulk, preventing LID in mc-Si.

Preventing light-induced degradation in multicrystalline silicon

NASA Astrophysics Data System (ADS)

Lindroos, J.; Boulfrad, Y.; Yli-Koski, M.; Savin, H.

2014-04-01

Multicrystalline silicon (mc-Si) is currently dominating the silicon solar cell market due to low ingot costs, but its efficiency is limited by transition metals, extended defects, and light-induced degradation (LID). LID is traditionally associated with a boron-oxygen complex, but the origin of the degradation in the top of the commercial mc-Si brick is revealed to be interstitial copper. We demonstrate that both a large negative corona charge and an aluminum oxide thin film with a built-in negative charge decrease the interstitial copper concentration in the bulk, preventing LID in mc-Si.

Zinc oxide tetrapods as efficient photocatalysts for organic pollutant degradation

NASA Astrophysics Data System (ADS)

Liu, Fangzhou; Leung, Yu Hang; Djurisić, Aleksandra B.; Liao, Changzhong; Shih, Kaimin

2014-03-01

Bisphenol A (BPA) and other organic pollutants from industrial wastewater have drawn increasing concern in the past decades regarding their environmental and biological risks, and hence developing strategies of effective degradation of BPA and other organic pollutants is imperative. Metal oxide nanostructures, in particular titanium oxide (TiO2) and zinc oxide (ZnO), have been demonstrated to exhibit efficient photodegradation of various common organic dyes. ZnO tetrapods are of special interest due to their low density of native defects which consequently lead to lower recombination losses and higher photocatalytic efficiency. Tetrapods can be obtained by relatively simple and low-cost vapor phase deposition in large quantity; the micron-scale size would also be advantageous for catalyst recovery. In this study, the photodegradation of BPA with ZnO tetrapods and TiO2 nanostructures under UV illumination were compared. The concentration of BPA dissolved in DI water was analyzed by high-performance liquid chromatography (HPLC) at specified time intervals. It was observed that the photocatalytic efficiency of ZnO tetrapods eventually surpassed Degussa P25 in free-standing form, and more than 80% of BPA was degraded after 60 min. Photodegradation of other organic dye pollutants by tetrapods and P25 were also examined. The superior photocatalytic efficiency of ZnO tetrapods for degradation of BPA and other organic dye pollutants and its correlation with the material properties were discussed.

Scaling Studies of Efficient Raman Converters.

DTIC Science & Technology

1983-07-01

allowed without deleterious effects due to competing processes. These processes include amplified spontaneous emission (Raman superfluorescence...tively introducing noise injection that could potentially degrade conversion efficiency and/or beam quality. The conditions under which these competing ...good beam qual- ity. Section 5.1 discusses Stokes injection level requirements in terms of suppressing competing effects which can reduce conversion

Preparation of magnetic imprinted graphene oxide composite for catalytic degradation of Congo red under dark ambient conditions.

PubMed

Yang, Xiaochao; You, Xiaoxiao; Zhang, Bin; Guo, Chuigen; Yu, Chaosheng

2017-10-01

Magnetic imprinted N-doped P25/Fe 3 O 4 -graphene oxide (MIGNT) was prepared with methyl orange as the dummy template and pyrrole as functional monomer for catalytic degradation of Congo red (CR). Hummers method and the hydrothermal method were used to synthesize Fe 3 O 4 -GO and N-doped P25, respectively. The results of adsorption and degradation experiments showed that the adsorption capacity and catalytic degradation ability of the imprinted composite for CR were obviously higher than those of a non-imprinted one. Moreover, the effect factors on degradation efficiency of CR, such as the initial concentration of CR, catalysis time, pH of the solution and temperature, were investigated. The MIGNT was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, a physical property measurement system and a thermal gravimetric analyzer. The degradation products of CR were detected with high performance liquid chromatography and a mass spectrometer. The MIGNT was a brand-new imprinted composite and had high degradation efficiency for CR under dark ambient conditions. The MIGNT could be recycled conveniently, due to its magnetic property, and could be used as an effective, environmentally friendly and low-cost catalytic degradation material for the treatment of water contaminated by CR.

An efficient method to predict and include Bragg curve degradation due to lung-equivalent materials in Monte Carlo codes by applying a density modulation

NASA Astrophysics Data System (ADS)

Baumann, Kilian-Simon; Witt, Matthias; Weber, Uli; Engenhart-Cabillic, Rita; Zink, Klemens

2017-05-01

Sub-millimetre-sized heterogeneities such as lung parenchyma cause Bragg peak degradation which can lead to an underdose of the tumor and an overdose of healthy tissue when not accounted for in treatment planning. Since commonly used treatment-planning CTs do not resolve the fine structure of lungs, this degradation can hardly be considered. We present a mathematical model capable of predicting and describing Bragg peak degradation due to a lung-equivalent geometry consisting of sub-millimetre voxels filled with either lung tissue or air. The material characteristic ‘modulation power’ is introduced to quantify the Bragg peak degradation. A strategy was developed to transfer the modulating effects of such fine structures to rougher structures such as 2 mm thick CT voxels, which is the resolution of typically used CTs. This is done by using the modulation power to derive a density distribution applicable to these voxels. By replacing the previously used sub-millimetre voxels by 2 mm thick voxels filled with lung tissue and modulating the lung tissue’s density in each voxel individually, we were able to reproduce the Bragg peak degradation. Hence a solution is found to include Bragg curve degradation due to lung-equivalent materials in Monte Carlo-based treatment-planning systems.

Graphene oxide (rGO)-metal oxide (TiO2/Fe3O4) based nanocomposites for the removal of methylene blue

NASA Astrophysics Data System (ADS)

Banerjee, Soma; Benjwal, Poonam; Singh, Milan; Kar, Kamal K.

2018-05-01

Herein, ternary nanocomposites based on titanium dioxide, ferric oxide and reduced graphene oxide (GO) have been developed for photocatalytic degradation of methylene blue. The nanocomposites are prepared by simple sol-gel and wet assembly methods with varying weight ratio of each components to obtain efficient photocatalytic degradation. Due to the synergistic effect among the three components, a swift removal of methylene blue becomes possible under visible and UV light. The rGO-Fe3O4-TiO2 nanocomposite having composition 1:1:2 has achieved maximum degradation of methylene blue from the aqueous solution. About 99% of the dye has been removed within 6 min under UV irradiation, while in presence of visible light, 94% has been degraded from the wastewater. The enhancement of photocatalytic activity in this ternary system is attributed to the efficient separation of charge carriers from TiO2 to rGO under the exposure of light and the initiation of photo-Fenton reaction due to the incorporated Fe3O4 nanoparticles in presence of H2O2, which provides highly reactive hydroxyl ions that mineralize the pollutants. All these results indicate that these ternary nanocomposites possess great potential for both UV and visible light driven methylene blue destruction from the wastewater.

Optimization and application of TiO₂/Ti-Pt photo fuel cell (PFC) to effectively generate electricity and degrade organic pollutants simultaneously.

PubMed

Li, Kan; Zhang, Hongbo; Tang, Tiantian; Xu, Yunlan; Ying, Diwen; Wang, Yalin; Jia, Jinping

2014-10-01

A TiO2/Ti-Pt photo fuel cell (PFC) was established to generate electricity and degrade organic pollutants simultaneously. The electricity generation was optimized through investigation the influences of photoanode calcination temperature and dissolve oxygen on the resistances existing in PFC. TiO2 light quantum yield was also improved in PFC which resulted in a higher PC degradation efficiency. Two kinds of real textile wastewaters were also employed in this PFC system, 62.4% and 50.0% Coulombic efficiency were obtained for 8 h treatment. These refractory wastewaters with high salinity may become good fuels in PFC because a) TiO2 has no selectivity and can degrade nearly any organic substance, b) no more electrolyte is needed due to the high salinity, c) the energy in wastes can be recovered to generate electricity. The electricity generated by the PFC was further applied on a TiO2/Ti rotating disk photoelectrocatalytic reactor. A bias voltage between 0.6 and 0.75 V could be applied and the PC degradation efficiency was significantly improved. This result was similar with that obtained by a 0.7 V DC power. Copyright © 2014 Elsevier Ltd. All rights reserved.

BiVO4 /N-rGO nano composites as highly efficient visible active photocatalyst for the degradation of dyes and antibiotics in eco system.

PubMed

Appavu, Brindha; Thiripuranthagan, Sivakumar; Ranganathan, Sudhakar; Erusappan, Elangovan; Kannan, Kathiravan

2018-04-30

Herein, we report the synthesis of novel nitrogen doped reduced graphene oxide/ BiVO 4 photo catalyst by single step hydrothermal method. The physicochemical properties of the catalysts were characterized using XRD, N 2 adsorption-desorption, Raman, XPS, SEM TEM, DRS-UV and EIS techniques. The synthesized catalysts were tested for their catalytic activity in the photo degradation of some harmful textile dyes (methylene blue & congo red) and antibiotics (metronidazole and chloramphenicol) under visible light irradiation. Reduced charge recombination and enhanced photocatalytic activity were observed due to the concerted effect between BiVO 4 and nitrogen-rGO. The degradation efficiency of BiVO 4 /N-rGO in the degradation of CR and MB was remarkably high i.e 95% and 98% under visible light irradiation. Similarly 95% of MTZ and 93% of CAP were degraded under visible light irradiation. HPLC studies implied that both the dyes and antibiotics were degraded to the maximum extent. The plausible photocatalytic mechanism on the basis of experimental results was suggested. Copyright © 2018 Elsevier Inc. All rights reserved.

Analytical method development of nifedipine and its degradants binary mixture using high performance liquid chromatography through a quality by design approach

NASA Astrophysics Data System (ADS)

Choiri, S.; Ainurofiq, A.; Ratri, R.; Zulmi, M. U.

2018-03-01

Nifedipin (NIF) is a photo-labile drug that easily degrades when it exposures a sunlight. This research aimed to develop of an analytical method using a high-performance liquid chromatography and implemented a quality by design approach to obtain effective, efficient, and validated analytical methods of NIF and its degradants. A 22 full factorial design approach with a curvature as a center point was applied to optimize of the analytical condition of NIF and its degradants. Mobile phase composition (MPC) and flow rate (FR) as factors determined on the system suitability parameters. The selected condition was validated by cross-validation using a leave one out technique. Alteration of MPC affected on time retention significantly. Furthermore, an increase of FR reduced the tailing factor. In addition, the interaction of both factors affected on an increase of the theoretical plates and resolution of NIF and its degradants. The selected analytical condition of NIF and its degradants has been validated at range 1 – 16 µg/mL that had good linearity, precision, accuration and efficient due to an analysis time within 10 min.

Application of Electro-Fenton Technology to Remediation of Polluted Effluents by Self-Sustaining Process

PubMed Central

Fernández de Dios, Maria Ángeles; Iglesias, Olaia; Pazos, Marta; Sanromán, Maria Ángeles

2014-01-01

The applicability of electro-Fenton technology to remediation of wastewater contaminated by several organic pollutants such as dyes and polycyclic aromatic hydrocarbons has been evaluated using iron-enriched zeolite as heterogeneous catalyst. The electro-Fenton technology is an advanced oxidation process that is efficient for the degradation of organic pollutants, but it suffers from the high operating costs due to the need for power investment. For this reason, in this study microbial fuel cells (MFCs) were designed in order to supply electricity to electro-Fenton processes and to achieve high treatment efficiency at low cost. Initially, the effect of key parameters on the MFC power generation was evaluated. Afterwards, the degradation of Reactive Black 5 dye and phenanthrene was evaluated in an electro-Fenton reactor, containing iron-enriched zeolite as catalyst, using the electricity supplied by the MFC. Near complete dye decolourization and 78% of phenanthrene degradation were reached after 90 min and 30 h, respectively. Furthermore, preliminary reusability tests of the developed catalyst showed high degradation levels for successive cycles. The results permit concluding that the integrated system is adequate to achieve high treatment efficiency with low electrical consumption. PMID:24723828

Enhanced cellulose degradation using cellulase-nanosphere complexes.

PubMed

Blanchette, Craig; Lacayo, Catherine I; Fischer, Nicholas O; Hwang, Mona; Thelen, Michael P

2012-01-01

Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

Enhanced Cellulose Degradation Using Cellulase-Nanosphere Complexes

PubMed Central

Blanchette, Craig; Lacayo, Catherine I.; Fischer, Nicholas O.; Hwang, Mona; Thelen, Michael P.

2012-01-01

Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production. PMID:22870287

Use of plan quality degradation to evaluate tradeoffs in delivery efficiency and clinical plan metrics arising from IMRT optimizer and sequencer compromises

PubMed Central

Wilkie, Joel R.; Matuszak, Martha M.; Feng, Mary; Moran, Jean M.; Fraass, Benedick A.

2013-01-01

Purpose: Plan degradation resulting from compromises made to enhance delivery efficiency is an important consideration for intensity modulated radiation therapy (IMRT) treatment plans. IMRT optimization and/or multileaf collimator (MLC) sequencing schemes can be modified to generate more efficient treatment delivery, but the effect those modifications have on plan quality is often difficult to quantify. In this work, the authors present a method for quantitative assessment of overall plan quality degradation due to tradeoffs between delivery efficiency and treatment plan quality, illustrated using comparisons between plans developed allowing different numbers of intensity levels in IMRT optimization and/or MLC sequencing for static segmental MLC IMRT plans. Methods: A plan quality degradation method to evaluate delivery efficiency and plan quality tradeoffs was developed and used to assess planning for 14 prostate and 12 head and neck patients treated with static IMRT. Plan quality was evaluated using a physician's predetermined “quality degradation” factors for relevant clinical plan metrics associated with the plan optimization strategy. Delivery efficiency and plan quality were assessed for a range of optimization and sequencing limitations. The “optimal” (baseline) plan for each case was derived using a clinical cost function with an unlimited number of intensity levels. These plans were sequenced with a clinical MLC leaf sequencer which uses >100 segments, assuring delivered intensities to be within 1% of the optimized intensity pattern. Each patient's optimal plan was also sequenced limiting the number of intensity levels (20, 10, and 5), and then separately optimized with these same numbers of intensity levels. Delivery time was measured for all plans, and direct evaluation of the tradeoffs between delivery time and plan degradation was performed. Results: When considering tradeoffs, the optimal number of intensity levels depends on the treatment site and on the stage in the process at which the levels are limited. The cost of improved delivery efficiency, in terms of plan quality degradation, increased as the number of intensity levels in the sequencer or optimizer decreased. The degradation was more substantial for the head and neck cases relative to the prostate cases, particularly when fewer than 20 intensity levels were used. Plan quality degradation was less severe when the number of intensity levels was limited in the optimizer rather than the sequencer. Conclusions: Analysis of plan quality degradation allows for a quantitative assessment of the compromises in clinical plan quality as delivery efficiency is improved, in order to determine the optimal delivery settings. The technique is based on physician-determined quality degradation factors and can be extended to other clinical situations where investigation of various tradeoffs is warranted. PMID:23822412

Fabrication of Unique Magnetic Bionanocomposite for Highly Efficient Removal of Hexavalent Chromium from Water

PubMed Central

Zhong, Yunlei; Qiu, Xun; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

2016-01-01

Biotreatment of hexavalent chromium has attracted widespread interest due to its cost effective and environmental friendliness. However, the difficult separation of biomass from aqueous solution and the slow hexavalent chromium bioreduction rate are bottlenecks for biotechnology application. In this approach, a core-shell structured functional polymer coated magnetic nanocomposite was prepared for enriching the hexavalent chromium. Then the nanocomposite was connected to the bacteria via amines on bacterial (Bacillus subtilis ATCC-6633) surface. Under optimal conditions, a series of experiments were launched to degrade hexavalent chromium from the aqueous solution using the as-prepared bionanocomposite. Results showed that B. subtilis@Fe3O4@mSiO2@MANHE (BFSM) can degrade hexavalent chromium from the water more effectively (a respectable degradation efficiency of about 94%) when compared with pristine B. subtilis and Fe3O4@mSiO2@MANHE (FSM). Moreover, the BFSM could be separated from the wastewater by magnetic separation technology conveniently due to the Fe3O4 core of FSM. These results indicate that the application of BFSM is a promising strategy for effective treating wastewater containing hexavalent chromium. PMID:27502074

Fabrication of Unique Magnetic Bionanocomposite for Highly Efficient Removal of Hexavalent Chromium from Water

NASA Astrophysics Data System (ADS)

Zhong, Yunlei; Qiu, Xun; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

2016-08-01

Biotreatment of hexavalent chromium has attracted widespread interest due to its cost effective and environmental friendliness. However, the difficult separation of biomass from aqueous solution and the slow hexavalent chromium bioreduction rate are bottlenecks for biotechnology application. In this approach, a core-shell structured functional polymer coated magnetic nanocomposite was prepared for enriching the hexavalent chromium. Then the nanocomposite was connected to the bacteria via amines on bacterial (Bacillus subtilis ATCC-6633) surface. Under optimal conditions, a series of experiments were launched to degrade hexavalent chromium from the aqueous solution using the as-prepared bionanocomposite. Results showed that B. subtilis@Fe3O4@mSiO2@MANHE (BFSM) can degrade hexavalent chromium from the water more effectively (a respectable degradation efficiency of about 94%) when compared with pristine B. subtilis and Fe3O4@mSiO2@MANHE (FSM). Moreover, the BFSM could be separated from the wastewater by magnetic separation technology conveniently due to the Fe3O4 core of FSM. These results indicate that the application of BFSM is a promising strategy for effective treating wastewater containing hexavalent chromium.

Bioelectricity-assisted partial degradation of linear polyacrylamide in a bioelectrochemical system.

PubMed

Cui, Yu-Zhi; Zhang, Jian; Sun, Min; Zhai, Lin-Feng

2015-01-01

The wide application of water-soluble linear polyacrylamides (PAMs) can cause serious environmental pollution. Biological treatment of PAMs receives very limited efficiency due to their recalcitrance to the microbial degradation. Here, we show the bioelectrochemical system (BES) can be used as an effective strategy to improve the biodegradation efficiency of PAMs. A linear PAM with viscosity-average molecular weight of 5 × 10(6) was treated in the anodic chamber of BES reactor, and the change of PAM structure during the degradation process was investigated. The anodic bacteria in the BES demonstrated abilities to utilize the PAM as the sole carbon and nitrogen source to generate electricity. Both the anode-attached and planktonic bacteria contributed to the electricity generation, while the anode-attached community exhibited stronger electron transfer ability than the planktonic one. The closed-circuit and open-circuit operations of the BES reactor obtained chemical oxygen demand (COD) removal efficiencies of 32.5 and 7.4 %, respectively, implying the generation of bioelectricity could enhance the biodegradation of PAM. Structure analysis suggested the carbon chain of PAM was partially degraded in the BES, producing polymeric products with lower molecular weight. The microbial cleavage of the carbon chain was proposed to start from the "head-to-head" linkages and end with the formation of ether bonds.

Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions.

PubMed

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N

2012-03-20

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation.

Efficient Degradation of TCE in Groundwater Using Pd and Electro-generated H2 and O2: A Shift in Pathway from Hydrodechlorination to Oxidation in the Presence of Ferrous Ions

PubMed Central

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N.

2012-01-01

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H2 and O2 is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H2O2 up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radical are detected due to decomposition of H2O2, slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na2SO4, NaCl, NaNO3, NaHCO3, K2SO4, CaSO4 and MgSO4 does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppresses degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation. PMID:22315993

Transient electroluminescence on pristine and degraded phosphorescent blue OLEDs

NASA Astrophysics Data System (ADS)

Niu, Quan; Blom, Paul W. M.; May, Falk; Heimel, Paul; Zhang, Minlu; Eickhoff, Christian; Heinemeyer, Ute; Lennartz, Christian; Crǎciun, N. Irina

2017-11-01

In state-of-the-art blue phosphorescent organic light-emitting diode (PHOLED) device architectures, electrons and holes are injected into the emissive layer, where they are carried by the emitting and hole transporting units, respectively. Using transient electroluminescence measurements, we disentangle the contribution of the electrons and holes on the transport and efficiency of both pristine and degraded PHOLEDs. By varying the concentration of hole transporting units, we show that for pristine PHOLEDs, the transport is electron dominated. Furthermore, degradation of the PHOLEDs upon electrical aging is not related to the hole transport but is governed by a decrease in the electron transport due to the formation of electron traps.

Application of ligninolytic potentials of a white-rot fungus Ganoderma lucidum for degradation of lindane.

PubMed

Kaur, Harsimran; Kapoor, Shammi; Kaur, Gaganjyot

2016-10-01

Lindane, a broad-spectrum organochlorine pesticide, has caused a widespread environmental contamination along with other pesticides due to wrong agricultural practices. The high efficiency, sustainability and eco-friendly nature of the bioremediation process provide an edge over traditional physico-chemical remediation for managing pesticide pollution. In the present study, lindane degradation was studied by using a white-rot fungus, Ganoderma lucidum GL-2 strain, grown on rice bran substrate for ligninolytic enzyme induction at 30 °C and pH 5.6 after incorporation of 4 and 40 ppm lindane in liquid as well as solid-state fermentation. The estimation of lindane residue was carried out by gas chromatography coupled to mass spectrometry (GC-MS) in the selected ion monitoring mode. In liquid-state fermentation, 100.13 U/ml laccase, 50.96 U/ml manganese peroxidase and 17.43 U/ml lignin peroxidase enzymes were obtained with a maximum of 75.50 % lindane degradation on the 28th day of incubation period, whereas under the solid-state fermentation system, 156.82 U/g laccase, 80.11 U/g manganese peroxidase and 18.61 U/g lignin peroxidase enzyme activities with 37.50 % lindane degradation were obtained. The lindane incorporation was inhibitory to the production of ligninolytic enzymes and its own degradation but was stimulatory for extracellular protein production. The dialysed crude enzyme extracts of ligninolytic enzymes were though efficient in lindane degradation during in vitro studies, but their efficiencies tend to decrease with an increase in the incubation period. Hence, lindane-degrading capabilities of G. lucidum GL-2 strain make it a potential candidate for managing lindane bioremediation at contaminated sites.

Least limiting water range of Udox soil under degraded pastures on different sun-exposed faces

NASA Astrophysics Data System (ADS)

Passos, Renato Ribeiro; Marciano da Costa, Liovando; Rodrigues de Assis, Igor; Santos, Danilo Andrade; Ruiz, Hugo Alberto; Guimarães, Lorena Abdalla de Oliveira Prata; Andrade, Felipe Vaz

2017-07-01

The efficient use of water is increasingly important and proper soil management, within the specificities of each region of the country, allows achieving greater efficiency. The South and Caparaó regions of Espírito Santo, Brazil are characterized by relief of `hill seas' with differences in the degree of pasture degradation due to sun exposure. The objective of this study was to evaluate the least limiting water range in Udox soil under degraded pastures with two faces of exposure to the sun and three pedoenvironments. In each pedoenvironment, namely Alegre, Celina, and Café, two areas were selected, one with exposure on the North/West face and the other on the South/East face. In each of these areas, undisturbed soil samples were collected at 0-10 cm depth to determine the least limiting water range. The exposed face of the pasture that received the highest solar incidence (North/West) presented the lowest values in least limiting water range. The least limiting water range proved to be a physical quality indicator for Udox soil under degraded pastures.

Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

PubMed

Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

2016-06-01

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact of humic acid on the photoreductive degradation of perfluorooctane sulfonate (PFOS) by UV/Iodide process.

PubMed

Sun, Zhuyu; Zhang, Chaojie; Chen, Pei; Zhou, Qi; Hoffmann, Michael R

2017-12-15

Iodide photolysis under UV illumination affords an effective method to produce hydrated electrons (e aq - ) in aqueous solution. Therefore, UV/Iodide photolysis can be utilized for the reductive degradation of many recalcitrant pollutants. However, the effect of naturally occurring organic matter (NOM) such as humic and fulvic acids (HA/FA), which may impact the efficiency of UV/Iodide photoreduction, is poorly understood. In this study, the UV photoreductive degradation of perfluorooctane sulfonate (PFOS) in the presence of I - and HA is studied. PFOS undergoes a relatively slow direct photoreduction in pure water, a moderate level of degradation via UV/Iodide, but a rapid degradation via UV/Iodide/HA photolysis. After 1.5 h of photolysis, 86.0% of the initial [PFOS] was degraded in the presence of both I - and HA with a corresponding defluorination ratio of 55.6%, whereas only 51.7% of PFOS was degraded with a defluorination ratio of 4.4% via UV/Iodide illumination in the absence of HA. The relative enhancement in the presence of HA in the photodegradation of PFOS can be attributed to several factors: a) HA enhances the effective generation of e aq - due to the reduction of I 2 , HOI, IO 3 - and I 3 - back to I - ; b) certain functional groups of HA (i.e., quinones) enhance the electron transfer efficiency as electron shuttles; c) a weakly-bonded association of I - and PFOS with HA increases the reaction probability; and d) absorption of UV photons by HA itself produces e aq - . The degradation and defluorination efficiency of PFOS by UV/Iodide/HA process is dependent on pH and HA concentration. As pH increases from 7.0 to 10.0, the enhancement effect of HA improves significantly. The optimal HA concentration for the degradation of 0.03 mM PFOS is 1.0 mg L -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

The different paths and potential risks of photo(-electro)-catalytic degradation for rhodamine B in water by graphene/TiO2 membrane.

PubMed

Ren, Miao; Liu, Haiyang; Qu, Jiao; Zhang, Yanan; Ma, Ying; Yuan, Xing

2018-03-07

The graphene (GR)/TiO 2 membrane was prepared by the sol-gel method and coated on the indium tin oxide (ITO) conductive glass, which showed high and stable photo(-electro)-catalytic activities to rhodamine B (Rh-B) in water. Characterization results showed that the GR was dispersed and wrapped in the needle-like TiO 2 . With GR/TiO 2 membrane and simulated sunlight irradiation, the removal efficiency of Rh-B (10 mg l -1 and pH at 5.4) arrived at 87.6% within 300 min. However, the higher removal efficiency for Rh-B reached to 97.8% by the photo-electro-catalytic degradation with the applied voltage 4 v for 30 min. The ·OH that generated in the photo-catalytic degradation process were responsible for Rh-B decomposition. The ·O 2 - played the significant role in the photo-electro-catalytic degradation of Rh-B. Furthermore, the decarboxylation was also occurred in the photo-electro-catalytic degradation for the Rh-B in water except for the deethylation and hydroxylation in the photo-catalytic degradation. In addition, the toxicities of the intermediates were calculated using the ECOSAR program and the EPIWIN software. The results indicated that the toxicities of intermediates from photo-electro-catalytic degradation for the Rh-B were higher than photo-catalytic degradation, due to the generation of decarboxylate.

Ultrafast detection in particle physics and positron emission tomography using SiPMs

NASA Astrophysics Data System (ADS)

Dolenec, R.; Korpar, S.; Križan, P.; Pestotnik, R.

2017-12-01

Silicon photomultiplier (SiPM) photodetectors perform well in many particle and medical physics applications, especially where good efficiency, insensitivity to magnetic field and precise timing are required. In Cherenkov time-of-flight positron emission tomography the requirements for photodetector performance are especially high. On average only a couple of photons are available for detection and the best possible timing resolution is needed. Using SiPMs as photodetectors enables good detection efficiency, but the large sensitive area devices needed have somewhat limited time resolution for single photons. We have observed an additional degradation of the timing at very low light intensities due to delayed events in distribution of signals resulting from multiple fired micro cells. In this work we present the timing properties of AdvanSiD ASD-NUV3S-P-40 SiPM at single photon level picosecond laser illumination and a simple modification of the time-walk correction algorithm, that resulted in reduced degradation of timing resolution due to the delayed events.

ZnO:Ag nanorods as efficient photocatalysts: Sunlight driven photocatalytic degradation of sulforhodamine B

NASA Astrophysics Data System (ADS)

Raji, R.; K. S., Sibi; K. G., Gopchandran

2018-01-01

Visible light responsive highly photocatalytic ZnO:Ag nanorods with varying Ag concentration were synthesized via co-precipitation method. X-ray diffraction analysis and high resolution transmission electron microscopy investigations confirmed the hexagonal wurtzite phase for these ZnO:Ag nanorods with preferential growth along the (101) plane. Raman shift and luminescence measurements indicated that the incorporation of Ag influences the lattice vibrational modes; there by causing distortion in lattice, inducing silent vibrational modes and emission behavior by quenching of both the band edge and visible emissions respectively. The photocatalytic performance of these nanorods as catalysts was tested by observing the photodegradation of a representative dye pollutant, viz., sulforhodamine B under sunlight irradiation. Photocatalytic performance was evaluated by determining the rate of reaction kinetics, photodegradation efficiency and mineralization efficiency. A high rate constant of 0.552 min-1, chemical oxygen demand value of 5.8 ppm and a mineralization efficiency of 94% were obtained when ZnO: Ag nanorods with an Ag content of 1.5 at.% were used as catalysts. The observed increase in photocatalytic efficiency with Ag content in ZnO:Ag nanorods is attributed to the electron scavenging action of silver, Schottky barrier between the Ag and ZnO interface and the better utilization of sunlight due to enhanced absorption due to plasmons in the visible region. BET analysis indicated that silver doping causes effective surface area of nanorods to increase, which in turn increases the photocatalytic efficiency. The possible mechanism for degradation of dye under sunlight irradiation is described with a schematic and the photostability of the ZnO:Ag nanorods were also tested through five repetitive cycles. This work suggests that the prepared ZnO:Ag nanorods are excellent reusable photocatalysts for the degradation of toxic organic waste in water, which causes severe threat to environment.

The quantity and quality of dissolved organic matter as supplementary carbon source impacts the pesticide-degrading activity of a triple-species bacterial biofilm.

PubMed

Horemans, Benjamin; Vandermaesen, Johanna; Breugelmans, Philip; Hofkens, Johan; Smolders, Erik; Springael, Dirk

2014-01-01

Effects of environmental dissolved organic matter (eDOM) that consists of various low concentration carbonic compounds on pollutant biodegradation by bacteria are poorly understood, especially when it concerns synergistic xenobiotic-degrading consortia where degradation depends on interspecies metabolic interactions. This study examines the impact of the quality and quantity of eDOM, supplied as secondary C-source, on the structure, composition and pesticide-degrading activity of a triple-species bacterial consortium in which the members synergistically degrade the phenylurea herbicide linuron, when grown as biofilms. Biofilms developing on 10 mg L⁻¹ linuron showed a steady-state linuron degradation efficiency of approximately 85 %. The three bacterial strains co-localized in the biofilms indicating syntrophic interactions. Subsequent feeding with eDOM or citrate in addition to linuron resulted into changes in linuron-degrading activity. A decrease in linuron-degrading activity was especially recorded in case of co-feeding with citrate and eDOM of high quality and was always associated with accumulation of the primary metabolite 3,4-dichloroaniline. Improvement of linuron degradation was especially observed with more recalcitrant eDOM. Addition of eDOM/citrate formulations altered biofilm architecture and species composition but without loss of any of the strains and of co-localization. Compositional shifts correlated with linuron degradation efficiencies. When the feed was restored to only linuron, the linuron-degrading activity rapidly changed to the level before the mixed-substrate feed. Meanwhile only minor changes in biofilm composition and structure were recorded, indicating that observed eDOM/citrate effects had been primarily due to repression/stimulation of linuron catabolic activity rather than to biofilm characteristics.

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.

A high-efficiency fibre double-scrambler prototype

NASA Astrophysics Data System (ADS)

Barnes, Stuart I.; MacQueen, Phillip J.

2010-07-01

Results for a high efficiency fibre double-scrambler are reported. The scrambler is based on the concept first presented by Casse and Vieira (1997) but with a substantial improvement in performance. The design uses a simple finite conjugate relay with large magnification followed by a combined scrambler/focal reducer singlet. This approach allows flexibility in the coupling of fibres with various focal ratios and diameters, and can be used to minimize loss of throughput due to focal ratio degradation. A prototype has been constructed using simple off-the-shelf optics which is shown to be capable of coupling a 15m long 300 μm fibre to a 5m long 320 μm fibre with an absolute efficiency of 75%. The focal ratio degradation (FRD) of the prototype is 7% when operated at f/3.65. A fully optimized version with both improved efficiency (>85%) and FRD is intended to be deployed as part of the Hobby Eberly Telescope HRS upgrade.

The Bioconcentration and Degradation of Nonylphenol and Nonylphenol Polyethoxylates by Chlorella vulgaris

PubMed Central

Sun, Hong-Wen; Hu, Hong-Wei; Wang, Lei; Yang, Ying; Huang, Guo-Lan

2014-01-01

Nonylphenol polyethoxylates (NPnEOs), a major class of nonionic surfactants, can easily enter into aquatic environments through various pathways due to their wide applications, which leads to the extensive existence of their relative stable metabolites, namely nonylphenol (NP) and mono- to tri-ethoxylates. This study investigated the bioconcentration and degradation of NP and NPnEO oligomers (n = 1–12) by a green algae, Chlorella vulgaris. Experimental results showed that C. vulgaris can remove NP from water phase efficiently, and bioconcentration and degradation accounted for approximately half of its loss, respectively, with a 48 h BCF (bioconcentration factor) of 2.42 × 103. Moreover, C. vulgaris could concentrate and degrade NPnEOs, distribution profiles of the series homologues of the NPnEOs in algae and water phase were quite different from the initial homologue profile. The 48 h BCF of the NPnEO homologues increased with the length of the EO chain. Degradation extent of total NPnEOs by C. vulgaris was 95.7%, and only 1.1% remained in water phase, and the other 3.2% remained in the algal cells. The algae removed the NPnEOs mainly through degradation. Due to rapid degradation, concentrations of the long chain NPnEO homologous in both water (n ≥ 2) and the algal phase (n ≥ 5) was quite low at the end of a 48 h experiment. PMID:24445260

Carbon catabolite repression and cell dispersal affect degradation of the xenobiotic compound 3,4-dichloroaniline in Comamonas testosteroni WDL7 biofilms.

PubMed

Horemans, Benjamin; Breugelmans, Philip; Hofkens, Johan; Springael, Dirk

2017-03-01

Organic pollutant degrading biofilms in natural ecosystems and water treatment systems are often exposed to other carbon sources in addition to the pollutant. The availability of auxiliary carbon sources can lead to surplus biomass growth, changes in biofilm structure and carbon catabolite repression (CCR) which together will affect pollutant degradation rate and efficiency of the system. To understand the interplay between these processes, continuous biofilms of the 3,4-dichloroaniline (3,4-DCA) degrading Comamonas testosteroni WDL7-RFP were grown in single- and dual-substrate conditions with 3,4-DCA and/or citrate and reciprocal effects on 3,4-DCA/citrate degradation, biofilm biomass and biofilm structure were examined. The main mechanism affecting 3,4-DCA degradation in biofilms in dual-substrate conditions was citrate-mediated CCR as reflected by a decrease in specific 3,4-DCA degrading activity. Growth on citrate partially compensated for the lowered specific 3,4-DCA degradation activity under dual substrate conditions but not to the extent expected from growth observed under single-substrate conditions with citrate. This was explained by higher residual 3,4-DCA concentrations in the presence of citrate that increased cell dispersal in the biofilms. Our results show hampered pollutant removal in biofilms due to a complex interplay of auxiliary organic C source utilization for growth affecting the specific pollutant degradation rate and changes in cell physiology due to increased exposure to the pollutant as a result of lowered pollutant degradation rates. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Wear of sharp aggregates in a rotating drum

NASA Astrophysics Data System (ADS)

Deiros Quintanilla, Ivan; Combe, Gaël; Emeriault, Fabrice; Toni, Jean-Benoît; Voivret, Charles; Ferellec, Jean François

2017-06-01

Aggregates constituting ballast layer wear due to the continuous passage of trains and during the necessary maintenance operations of the track. In order to develop efficient solutions for ballasted tracks design and maintenance, a proper knowledge of the degradation laws of ballast grains is needed. In tribology, the amount of wear due to friction when two surfaces are in contact is classically predicted by Archard's equation. However, due to the continuous evolution of grain angularity and roughness, at the macro-scale wear coefficient cannot be assumed to remain constant, but will depend on the state of degradation of the grain surface. In order to adjust the model to this particular case, the Micro-Deval Attrition test is used. The rotating drum is stopped at intermediate stages and the amount of generated fine particles is measured. Thus the curve of mass loss along time is built. These results are then linked to Archard's model using the values of contact forces and relative displacements extracted from discrete element simulations. Finally, a morphology analysis is performed tracking shape and roughness parameters at different stages of degradation using X-ray tomography and a laser profilometer.

Analytical determination of propeller performance degradation due to ice accretion

NASA Technical Reports Server (NTRS)

Miller, T. L.

1986-01-01

A computer code has been developed which is capable of computing propeller performance for clean, glaze, or rime iced propeller configurations, thereby providing a mechanism for determining the degree of performance degradation which results from a given icing encounter. The inviscid, incompressible flow field at each specified propeller radial location is first computed using the Theodorsen transformation method of conformal mapping. A droplet trajectory computation then calculates droplet impingement points and airfoil collection efficiency for each radial location, at which point several user-selectable empirical correlations are available for determining the aerodynamic penalities which arise due to the ice accretion. Propeller performance is finally computed using strip analysis for either the clean or iced propeller. In the iced mode, the differential thrust and torque coefficient equations are modified by the drag and lift coefficient increments due to ice to obtain the appropriate iced values. Comparison with available experimental propeller icing data shows good agreement in several cases. The code's capability to properly predict iced thrust coefficient, power coefficient, and propeller efficiency is shown to be dependent on the choice of empirical correlation employed as well as proper specification of radial icing extent.

Marine Oil-Degrading Microorganisms and Biodegradation Process of Petroleum Hydrocarbon in Marine Environments: A Review.

PubMed

Xue, Jianliang; Yu, Yang; Bai, Yu; Wang, Liping; Wu, Yanan

2015-08-01

Due to the toxicity of petroleum compounds, the increasing accidents of marine oil spills/leakages have had a significant impact on our environment. Recently, different remedial techniques for the treatment of marine petroleum pollution have been proposed, such as bioremediation, controlled burning, skimming, and solidifying. (Hedlund and Staley in Int J Syst Evol Microbiol 51:61-66, 2001). This review introduces an important remedial method for marine oil pollution treatment-bioremediation technique-which is considered as a reliable, efficient, cost-effective, and eco-friendly method. First, the necessity of bioremediation for marine oil pollution was discussed. Second, this paper discussed the species of oil-degrading microorganisms, degradation pathways and mechanisms, the degradation rate and reaction model, and the factors affecting the degradation. Last, several suggestions for the further research in the field of marine oil spill bioremediation were proposed.

Efficiency degradation due to tracking errors for point focusing solar collectors

NASA Technical Reports Server (NTRS)

Hughes, R. O.

1978-01-01

An important parameter in the design of point focusing solar collectors is the intercept factor which is a measure of efficiency and of energy available for use in the receiver. Using statistical methods, an expression of the expected value of the intercept factor is derived for various configurations and control law implementations. The analysis assumes that a radially symmetric flux distribution (not necessarily Gaussian) is generated at the focal plane due to the sun's finite image and various reflector errors. The time-varying tracking errors are assumed to be uniformly distributed within the threshold limits and allows the expected value calculation.

Toward a Real-Time Measurement-Based System for Estimation of Helicopter Engine Degradation Due to Compressor Erosion

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Simo, Donald L.

2007-01-01

This paper presents a preliminary demonstration of an automated health assessment tool, capable of real-time on-board operation using existing engine control hardware. The tool allows operators to discern how rapidly individual turboshaft engines are degrading. As the compressor erodes, performance is lost, and with it the ability to generate power. Thus, such a tool would provide an instant assessment of the engine s fitness to perform a mission, and would help to pinpoint any abnormal wear or performance anomalies before they became serious, thereby decreasing uncertainty and enabling improved maintenance scheduling. The research described in the paper utilized test stand data from a T700-GE-401 turboshaft engine that underwent sand-ingestion testing to scale a model-based compressor efficiency degradation estimation algorithm. This algorithm was then applied to real-time Health Usage and Monitoring System (HUMS) data from a T700-GE-701C to track compressor efficiency on-line. The approach uses an optimal estimator called a Kalman filter. The filter is designed to estimate the compressor efficiency using only data from the engine s sensors as input.

A distributed real-time model of degradation in a solid oxide fuel cell, part I: Model characterization

NASA Astrophysics Data System (ADS)

Zaccaria, V.; Tucker, D.; Traverso, A.

2016-04-01

Despite the high efficiency and flexibility of fuel cells, which make them an attractive technology for the future energy generation, their economic competitiveness is still penalized by their short lifetime, due to multiple degradation phenomena. As a matter of fact, electrochemical performance of solid oxide fuel cells (SOFCs) is reduced because of different degradation mechanisms, which depend on operating conditions, fuel and air contaminants, impurities in materials, and others. In this work, a real-time, one dimensional (1D) model of a SOFC is used to simulate the effects of voltage degradation in the cell. Different mechanisms are summarized in a simple empirical expression that relates degradation rate to cell operating parameters (current density, fuel utilization and temperature), on a localized basis. Profile distributions of different variables during cell degradation are analyzed. In particular, the effect of degradation on current density, temperature, and total resistance of the cell are investigated. An analysis of localized degradation effects shows how different parts of the cell degrade at a different time rate, and how the various profiles are redistributed along the cell as consequence of different degradation rates.

Degradation of dye Procion Red MX-5B by electrolytic and electro-irradiated technologies using diamond electrodes.

PubMed

Cotillas, Salvador; Clematis, Davide; Cañizares, Pablo; Carpanese, Maria Paola; Rodrigo, Manuel A; Panizza, Marco

2018-05-01

This work focuses on the treatment of synthetic wastewater polluted with dye Procion Red MX-5B by different Electrochemical Advanced Oxidation Processes (EAOP) based on diamond anodes. The influence of the current density and the supporting electrolyte has been studied on dye removal and total mineralization of the organic matter. Results show that electrolysis with diamond electrodes is a suitable technology for an efficient degradation of dye. Nonetheless, the process efficiency increases when using chloride as supporting electrolyte because of the electrochemical generation of hypochlorite in wastewater which significantly contribute to dye removal. On the contrary, the total mineralization of the organic matter is more efficient in sulfate media. In this case, large amounts of peroxodisulfate are electrogenerated, favoring the complete removal of total organic carbon (TOC). On the other hand, lower current densities (10 mA cm -2 ) lead to a more efficient removal of both dye and TOC due to the mass transfer limitations of the technology. Finally, the coupling of UV light irradiation or ultrasound to electrolysis significantly improves the process performance, being photoelectrolysis the most efficient technology for the treatment of wastewater polluted with Procion Red MX-5B. This fact is due to the potential production of free chlorine or sulfate radicals that takes place by the activation of the electrogenerated oxidants. These species are more reactive than oxidants and, therefore, they quickly attack the organic matter present in wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rectenna session: Micro aspects

NASA Technical Reports Server (NTRS)

Gutmann, R. J.

1980-01-01

Two micro aspects of rectenna design are discussed: evaluation of the degradation in net rectenna RF to DC conversion efficiency due to power density variations across the rectenna (power combining analysis) and design of Yagi-Uda receiving elements to reduce rectenna cost by decreasing the number of conversion circuits (directional receiving elements). The first of these involves resolving a fundamental question of efficiency potential with a rectenna, while the second involves a design modification with a large potential cost saving.

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

NASA Astrophysics Data System (ADS)

Nada, Amr A.; Tantawy, Hesham R.; Elsayed, Mohamed A.; Bechelany, Mikhael; Elmowafy, Mohamed E.

2018-04-01

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).

Comparison of efficiency degradation in polycrystalline-Si and CdTe thin-film PV modules via accelerated lifecycle testing

NASA Astrophysics Data System (ADS)

Lai, T.; Potter, B. G.; Simmons-Potter, K.

2017-08-01

Thin-film solar cells normally have the shortest energy payback time due to their simpler mass-production process compared to polycrystalline-Si photovoltaic (PV) modules, despite the fact that crystalline-Si-based technology typically has a longer total lifetime and a higher initial power conversion efficiency. For both types of modules, significant aging occurs during the first two years of usage with slower long-term aging over the module lifetime. The PV lifetime and the return-on-investment for local PV system installations rely on long-term device performance. Understanding the efficiency degradation behavior under a given set of environmental conditions is, therefore, a primary goal for experimental research and economic analysis. In the present work, in-situ measurements of key electrical characteristics (J, V, Pmax, etc.) in polycrystalline-Si and CdTe thin-film PV modules have been analyzed. The modules were subjected to identical environmental conditions, representative of southern Arizona, in a full-scale, industrial-standard, environmental degradation chamber, equipped with a single-sun irradiance source, temperature, and humidity controls, and operating an accelerated lifecycle test (ALT) sequence. Initial results highlight differences in module performance with environmental conditions, including temperature de-rating effects, for the two technologies. Notably, the thin-film CdTe PV module was shown to be approximately 15% less sensitive to ambient temperature variation. After exposure to a seven-month equivalent compressed night-day weather cycling regimen the efficiency degradation rates of both PV technology types were obtained and will be discussed.

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

NASA Astrophysics Data System (ADS)

Ahmed, Oumer

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

In vitro skin decontamination of the organophosphorus pesticide Paraoxon with nanometric cerium oxide CeO2.

PubMed

Salerno, Alicia; Devers, Thierry; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Josse, Denis; Briançon, Stéphanie

2017-04-01

Organophosphorus compounds (OP), which mainly penetrate via the percutaneous pathway, represent a threat for both military and civilians. Body surface decontamination is vital to prevent victims poisoning. The development of a cost-effective formulation, which could be efficient and easy to handle in case of mass contamination, is therefore crucial. Metal oxides nanoparticles, due their large surface areas and the large amount of highly reactive sites, present high reactivity towards OP. First, this study aimed at evaluating the reaction of CeO 2 nanoparticles, synthetized by microwave path and calcined at 500 or 600 °C, with Paraoxon (POX) in aqueous solution. Results showed that both nanoparticles degraded 60%-70% of POX. CeO 2 calcined at 500 °C, owing to its larger specific area, was the most effective. Moreover, the degradation was significantly increased under Ultra-Violet irradiation (initial degradation rate doubled). Then, skin decontamination was studied in vitro using the Franz cell method with pig-ear skin samples. CeO 2 powder and an aqueous suspension of CeO 2 (CeO 2 -W) were applied 1 h after POX exposure. The efficiency of decontamination, including removal and/or degradation of POX, was compared to Fuller's earth (FE) and RSDL lotion which are, currently, the most efficient systems for skin decontamination. CeO 2 -W and RSDL were the most efficient to remove POX from the skin surface and decrease skin absorption by 6.4 compared to the control not decontaminated. FE reduced significantly (twice) the absorbed fraction of POX, contrarily to CeO 2 powder. Considering only the degradation rate of POX, the products ranged in the order CeO 2  > RSDL > CeO 2 -W > FE (no degradation). This study showed that CeO 2 nanoparticles are a promising material for skin decontamination of OP if formulated as a dispersion able to remove POX like CeO 2 -W and to degrade it as CeO 2 powder. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Facile synthesis of zinc oxide nanoparticles decorated graphene oxide composite via simple solvothermal route and their photocatalytic activity on methylene blue degradation.

PubMed

Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Perumal, Suguna; Karthikeyan, Dhanapalan; Lee, Yong Rok

2016-09-01

Zinc oxide nanoparticles decorated graphene oxide (ZnO@GO) composite was synthesized by simple solvothermal method where zinc oxide (ZnO) nanoparticles and graphene oxide (GO) were synthesized via simple thermal oxidation and Hummers method, respectively. The obtained materials were thoroughly characterized by various physico-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Raman spectrum shows the intensity of D to G value was close to one which confirms the obtained GO and ZnO@GO composite possesses moderate graphitization. TEM images shows the ZnO nanoparticles mean size of 15±5nm were dispersed over the wrinkled graphene layers. The photocatalytic performance of ZnO@GO composite on degradation of methylene blue (MB) is investigated and the results show that the GO plays an important role in the enhancement of photocatalytic performance. The synthesized ZnO@GO composite achieves a maximum degradation efficiency of 98.5% in a neutral solution under UV-light irradiation for 15min as compared with pure ZnO (degradation efficiency is 49% after 60min of irradiation) due to the increased light absorption, the reduced charge recombination with the introduction of GO. Moreover, the resulting ZnO@GO composite possesses excellent degradation efficiency as compared to ZnO nanoparticles alone on MB. Copyright © 2016 Elsevier B.V. All rights reserved.

Aerobic TCE degradation by encapsulated toluene-oxidizing bacteria, Pseudomonas putida and Bacillus spp.

PubMed

Kim, Seungjin; Bae, Wookeun; Hwang, Jungmin; Park, Jaewoo

2010-01-01

The degradation rates of toluene and trichloroethylene (TCE) by Pseudomonas putida and Bacillus spp. that were encapsulated in polyethylene glycol (PEG) polymers were evaluated in comparison with the results of exposure to suspended cultures. PEG monomers were polymerized together with TCE-degrading microorganisms, such that the cells were encapsulated in and protected by the matrices of the PEG polymers. TCE concentrations were varied from 0.1 to 1.5 mg/L. In the suspended cultures of P. putida, the TCE removal rate decreased as the initial TCE concentration increased, revealing TCE toxicity or a limitation of reducing power, or both. When the cells were encapsulated, an initial lag period of about 10-20 h was observed for toluene degradation. Once acclimated, the encapsulated P. putida cultures were more tolerant to TCE at an experimental range of 0.6-1.0 mg/L and gave higher transfer efficiencies (mass TCE transformed/mass toluene utilized). When the TCE concentration was low (e.g., 0.1 mg/L) the removal of TCE per unit mass of cells (specific removal) was significantly lower, probably due to a diffusion limitation into the PEG pellet. Encapsulated Bacillus spp. were able to degrade TCE cometabolically. The encapsulated Bacillus spp. gave significantly higher values than did P. putida in the specific removal and the transfer efficiency, particularly at relatively high TCE concentration of approximately 1.0±0.5 mg/L. The transfer efficiency by encapsulated Bacillus spp. in this study was 0.27 mgTCE/mgToluene, which was one to two orders of magnitude greater than the reported values.

Photocatalytic degradation of perfluorooctanoic acid with beta-Ga2O3 in anoxic aqueous solution.

PubMed

Zhao, Baoxiu; Lv, Mou; Zhou, Li

2012-01-01

Perfluorooctanoic acid (PFOA) is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical (HO*) due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with beta-Ga2O3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron (e(cb-)) coming from the beta-Ga2O3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids (PFCAs, CnF2n+i1COOH, 1 < or = n < or = 6) were the dominant products. Furthermore, the concentration of F- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N2. The degradation reaction followed first-order kinetics (k = 0.0239 min(-1), t1/2 = 0.48 hr). PFCAs (CnF2n+1COOH, 1 < or = n < or = 7) were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves e(cb-) attacking the carboxyl of CnF2n+1COOH, resulting in decarboxylation and the generation of CnF2n+1*. The produced CnF2n+1* reacted with H2O, forming CnF2n+1OH, then CnF2n+1OH underwent HF loss and hydrolysis to form CnF2n+1COOH.

High efficiency graphene coated copper based thermocells connected in series

NASA Astrophysics Data System (ADS)

Sindhuja, Mani; Indubala, Emayavaramban; Sudha, Venkatachalam; Harinipriya, Seshadri

2018-04-01

Conversion of low-grade waste heat into electricity had been studied employing single thermocell or flowcells so far. Graphene coated copper electrodes based thermocells connected in series displayed relatively high efficiency of thermal energy harvesting. The maximum power output of 49.2W/m2 for normalized cross sectional electrode area is obtained at 60ºC of inter electrode temperature difference. The relative carnot efficiency of 20.2% is obtained from the device. The importance of reducing the mass transfer and ion transfer resistance to improve the efficiency of the device is demonstrated. Degradation studies confirmed mild oxidation of copper foil due to corrosion caused by the electrolyte.

Rhamnolipid mediated enhanced degradation of chlorpyrifos by bacterial consortium in soil-water system.

PubMed

Singh, Partapbir; Saini, Harvinder Singh; Raj, Mayil

2016-12-01

The study was conducted with the aim to develop an environmentally compatible bio-based system which may rapidly detoxify soil and water polluted by inordinate use of organophosphate (OP) pesticides. Chlorpyrifos was used as model pesticide as it degrade slowly due to its low aqueous phase solubility (2ppm) and formation of antibacterial intermediate 3,5,6, trichloropyridinol (TCP). Five potential bacteria used in this study belonging to genus Pseudomonas, Klebsiella, Stenotrophomonas, Ochrobactrum and Bacillus and their mixed culture system efficiently degraded chlorpyrifos and its toxic intermediates TCP and diethylthiophosphate (DETP) in aqueous medium. However, degradation rate in soil-water based slurry system was slow as it took 10 days to degrade 82% of added chlorpyrifos (50mg/kg) by a potential mixed culture CS2 comprised of isolates F-3 and CH-y. This might be due to strong sorption affinity of chlorpyrifos to soil components which limits its bioavailability. Hence, a crude rhamnolipid biosurfactant produced by ChlD was used which improved the aqueous phase solubility of chlorpyrifos by 2-15 folds. This supported CS2 to attain 30% higher degradation within short period of 6 days as compared to biotic control without surfactant. Thus, this combination of mixed bacterial population with biosurfactant significantly improved the rate of chlorpyrifos degradation in soil without accumulation of toxic intermediates. This environmentally benign biosurfactant may be produced "in situ" and can replace commonly used toxic synthetic surfactants for bioremediation purposes. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed

Koskela, Harri; Hakala, Ullastiina; Vanninen, Paula

2010-06-15

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

Bimetallic Au-Pd nanoparticles on 2D supported graphitic carbon nitride and reduced graphene oxide sheets: A comparative photocatalytic degradation study of organic pollutants in water.

PubMed

Darabdhara, Gitashree; Das, Manash R

2018-04-01

Novel and sustainable bimetallic nanoparticles of Au-Pd on 2D graphitic carbon nitride (g-C 3 N 4 ) and reduced graphene oxide (rGO) sheets was designed adopting an eco-friendly chemical route to obtain Au-Pd/g-C 3 N 4 and Au-Pd/rGO, respectively. Elimination of hazardous pollutants, particularly phenol from water is urgent for environment remediation due to its significant carcinogenicity. Considering this aspect, the Au-Pd/g-C 3 N 4 and Au-Pd/rGO nanocomposites are used as photocatalyst towards degradation of toxic phenol, 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) under natural sunlight and UV light irradiation. Au-Pd/g-C 3 N 4 nanocomposite exhibited higher activity then Au/g-C 3 N 4 , Pd/g-C 3 N 4 and Au-Pd/rGO nanocomposites with more than 95% degradation in 180 min under sunlight. The obtained degradation efficiency of our materials is better than many other reported photocatalysts. Incorporation of nitrogen atoms in the carbon skeleton of g-C 3 N 4 provides much better properties to Au-Pd/g-C 3 N 4 nanocomposite than carbon based Au-Pd/rGO leading to its higher degradation efficiency. Due to the presence of these nitrogen atoms and some defects, g-C 3 N 4 possesses appealing electrical, chemical and functional properties. Photoluminescence results further revealed the efficient charge separation and delayed recombination of photo-induced electron-hole pairs in the Au-Pd/g-C 3 N 4 nanocomposite. Generation of reactive oxygen species during photocatalysis is well explained through photoluminescence study and the sustainability of these photocatalyst was ascertained through reusability study up to eight and five consecutive cycles for Au-Pd/g-C 3 N 4 and Au-Pd/rGO nanocomposites, respectively without substantial loss in its activity. Characterization of the photocatalysts after reaction signified the stability of the nanocomposites and added advantage to our developed photocatalytic system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Production of pyrite nanoparticles using high energy planetary ball milling for sonocatalytic degradation of sulfasalazine.

PubMed

Khataee, Alireza; Fathinia, Siavash; Fathinia, Mehrangiz

2017-01-01

Sonocatalytic performance of pyrite nanoparticles was evaluated by the degradation of sulfasalazine (SSZ). Pyrite nanoparticles were produced via a high energy mechanical ball milling (MBM) in different processing time from 2h to 6h, in the constant milling speed of 320rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) confirmed the production of pyrite nanoparticles during 6h of ball milling with the average size distribution of 20-80nm. The effects of various operational parameters including pH value, catalyst amount (mg/L), SSZ concentration (mg/L), ultrasonic frequency (kHz) and reaction time on the SSZ removal efficiency were examined. The obtained results showed that the maximum removal efficiency of 97.00% was obtained at pH value of 4, catalyst dosage of 0.5g/L, SSZ concentration of 10mg/L and reaction time of 30min. Experimental results demonstrated that the kinetic of the degradation process can be demonstrated using Langmuir-Hinshelwood (L-H) kinetic model. The effect of different inorganic ions such as Cl - , CO 3 2- and SO 4 2- was investigated on the L-H reaction rate (k r ) and adsorption (K s ) constants. Results showed that the presence of the mentioned ions significantly influenced the L-H constants. The impact of ethanol as a OH radical scavenger and some enhancers including H 2 O 2 and K 2 S 2 O 8 was investigated on the SSZ removal efficiency. Accordingly, the presence of ethanol suppressed SSZ degradation due to the quenching of OH radicals and the addition of K 2 S 2 O 8 and H 2 O 2 increased the SSZ removal efficiency, due to the formation of SO 4 - and additional OH radicals, respectively. Under the identical conditions of operating parameters, pyrite nanoparticles maintained their catalytic activity during four consecutive runs. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradation of nitrobenzene wastewater in an acidic environment by Ti(IV)/H2O2/O3 in a rotating packed bed.

PubMed

Yang, Peizhen; Luo, Shuai; Liu, Youzhi; Jiao, Weizhou

2018-06-23

The rotating packed bed (RPB) as a continuous flow reactor performs very well in degradation of nitrobenzene wastewater. In this study, acidic nitrobenzene wastewater was degraded using ozone (O 3 ) combined with hydrogen peroxide and titanium ions (Ti(IV)/H 2 O 2 /O 3 ) or using only H 2 O 2 /O 3 in a RPB. The degradation efficiency of nitrobenzene by Ti(IV)/H 2 O 2 /O 3 is roughly 16.84% higher than that by H 2 O 2 /O 3 , and it reaches as high as 94.64% in 30 min at a H 2 O 2 /O 3 molar ratio of 0.48. It is also found that the degradation efficiency of nitrobenzene is significantly affected by the high gravity factor, H 2 O 2 /O 3 molar ratio, and Ti(IV) concentration, and it reaches a maximum at a high gravity factor of 40, a Ti(IV) concentration of 0.50 mmol/L, a pH of 4.0, a H 2 O 2 /O 3 molar ratio of 0.48, a liquid flow rate of 120 L/h, and an initial nitrobenzene concentration of 1.22 mmol/L. Both direct ozonation and indirect ozonation are involved in the reaction of O 3 with organic pollutants. The indirect ozonation due to the addition of different amounts of tert-butanol (·OH scavenger) in the system accounts for 84.31% of the degradation efficiency of nitrobenzene, indicating that the nitrobenzene is dominantly oxidized by ·OH generated in the RPB-Ti(IV)/H 2 O 2 /O 3 process. Furthermore, the possible oxidative degradation mechanisms are also proposed to better understand the role of RPB in the removal of pollutants. Graphical abstract ᅟ.

Electrical energy per order and current efficiency for electrochemical oxidation of p-chlorobenzoic acid with boron-doped diamond anode.

PubMed

Lanzarini-Lopes, Mariana; Garcia-Segura, Sergi; Hristovski, Kiril; Westerhoff, Paul

2017-12-01

Electrochemical oxidation (EO) is an advanced oxidation process for water treatment to mineralize organic contaminants. While proven to degrade a range of emerging pollutants in water, less attention has been given to quantify the effect of operational variables such applied current density and pollutant concentration on efficiency and energy requirements. Particular figures of merit were mineralization current efficiency (MCE) and electrical energy per order (E EO ). Linear increases of applied current exponentially decreased the MCE due to the enhancement of undesired parasitic reactions that consumed generated hydroxyl radical. E EO values ranged from 39.3 to 331.8 kW h m -3 order -1 . Increasing the applied current also enhanced the E EO due to the transition from kinetics limited by current to kinetics limited by mass transfer. Further increases in current did not influence the removal rate, but it raised the E EO requirement. The E EO requirement diminished when decreasing initial pollutant loading with the increase of the apparent kinetic rate because of the relative availability of oxidant per pollutant molecule in solution at a defined current. Oxidation by-products released were identified, and a plausible degradative pathway has been suggested. Copyright © 2017. Published by Elsevier Ltd.

Oxidative degradation of phenols in sono-Fenton-like systems upon high-frequency ultrasound irradiation

NASA Astrophysics Data System (ADS)

Aseev, D. G.; Sizykh, M. R.; Batoeva, A. A.

2017-12-01

The kinetics of oxidative degradation of phenol and chlorophenols upon acoustic cavitation in the megahertz range (1.7 MHz) is studied experimentally in model systems, and the involvement of in situ generated reactive oxygen species (ROSs) is demonstrated. The phenols subjected to high frequency ultrasound (HFUS) are ranked in terms of their rate of conversion: 2,4,6-trichlorophenol > 2,4-dichlorophenol 2-chlorophenol > 4-chlorophenol phenol. Oxidative degradation upon HFUS irradiation is most efficient at low concentrations of pollutants, due to the low steady-state concentrations of the in situ generated ROSs. A dramatic increase is observed in the efficiency of oxidation in several sonochemical oxidative systems (HFUS in combination with other chemical oxidative factors). The system with added Fe2+ (a sono-Fenton system) derives its efficiency from hydrogen peroxide generated in situ as a result of the recombination of OH radicals. The S2O8 2-/Fe2+/HFUS system has a synergetic effect on substrate oxidation that is attributed to a radical chain mechanism. In terms of the oxidation rates, degrees of conversion, and specific energy efficiencies of 4-chlorophenol oxidation based on the amount of oxidized substance per unit of expended energy the considered sonochemical oxidative systems form the series HFUS < S2O8 2-/HFUS < S2O8 2-/Fe2+/HFUS.

Mushroom as a product and their role in mycoremediation

PubMed Central

2014-01-01

Mushroom has been used for consumption as product for a long time due to their flavor and richness in protein. Mushrooms are also known as mycoremediation tool because of their use in remediation of different types of pollutants. Mycoremediation relies on the efficient enzymes, produced by mushroom, for the degradation of various types of substrate and pollutants. Besides waste degradation, mushroom produced a vendible product for consumption. However, sometimes they absorb the pollutant in their mycelium (biosorption process) and cannot be consumed due to absorbed toxicants. This article reviews the achievement and current status of mycoremediation technology based on mushroom cultivation for the remediation of waste and also emphasizes on the importance of mushroom as product. This critical review is also focused on the safety aspects of mushroom cultivation on waste. PMID:24949264

Mild extraction methods using aqueous glucose solution for the analysis of natural dyes in textile artefacts dyed with Dyer's madder (Rubia tinctorum L.).

PubMed

Ford, Lauren; Henderson, Robert L; Rayner, Christopher M; Blackburn, Richard S

2017-03-03

Madder (Rubia tinctorum L.) has been widely used as a red dye throughout history. Acid-sensitive colorants present in madder, such as glycosides (lucidin primeveroside, ruberythric acid, galiosin) and sensitive aglycons (lucidin), are degraded in the textile back extraction process; in previous literature these sensitive molecules are either absent or present in only low concentrations due to the use of acid in typical textile back extraction processes. Anthraquinone aglycons alizarin and purpurin are usually identified in analysis following harsh back extraction methods, such those using solvent mixtures with concentrated hydrochloric acid at high temperatures. Use of softer extraction techniques potentially allows for dye components present in madder to be extracted without degradation, which can potentially provide more information about the original dye profile, which varies significantly between madder varieties, species and dyeing technique. Herein, a softer extraction method involving aqueous glucose solution was developed and compared to other back extraction techniques on wool dyed with root extract from different varieties of Rubia tinctorum. Efficiencies of the extraction methods were analysed by HPLC coupled with diode array detection. Acidic literature methods were evaluated and they generally caused hydrolysis and degradation of the dye components, with alizarin, lucidin, and purpurin being the main compounds extracted. In contrast, extraction in aqueous glucose solution provides a highly effective method for extraction of madder dyed wool and is shown to efficiently extract lucidin primeveroside and ruberythric acid without causing hydrolysis and also extract aglycons that are present due to hydrolysis during processing of the plant material. Glucose solution is a favourable extraction medium due to its ability to form extensive hydrogen bonding with glycosides present in madder, and displace them from the fibre. This new glucose method offers an efficient process that preserves these sensitive molecules and is a step-change in analysis of madder dyed textiles as it can provide further information about historical dye preparation and dyeing processes that current methods cannot. The method also efficiently extracts glycosides in artificially aged samples, making it applicable for museum textile artefacts. Copyright © 2017 Elsevier B.V. All rights reserved.

Rectenna session: Micro aspects. [energy conversion

NASA Technical Reports Server (NTRS)

Gutmann, R. J.

1980-01-01

Two micro aspects of the rectenna design are addressed: evaluation of the degradation in net rectenna RF to DC conversion efficiency due to power density variations across the rectenna (power combining analysis) and design of Yagi-Uda receiving elements to reduce rectenna cost by decreasing the number of conversion circuits (directional receiving elements). The first of these micro aspects involves resolving a fundamental question of efficiency potential with a rectenna, while the second involves a design modification with a large potential cost saving.

Analysis of the Effects of Impurities in Silicon. [to determine solar cell efficiency

NASA Technical Reports Server (NTRS)

Wohlgemuth, J. H.; Lafky, W. M.; Burkholder, J. H.

1979-01-01

A solar cell fabrication and analysis program to determine the effects on the resultant solar cell efficiency of impurities incorporated into silicon is conducted. Flight quality technologies and quality assurance are employed to assure that variations in cell performance are due to the impurities incorporated in the silicon. The type and level of impurity doping in each test lot is given and the mechanism responsible for the degradation of cell performance is identified and correlated to the doped impurities.

Paracetamol degradation intermediates and toxicity during photo-Fenton treatment using different iron species.

PubMed

Trovó, Alam G; Pupo Nogueira, Raquel F; Agüera, Ana; Fernandez-Alba, Amadeo R; Malato, Sixto

2012-10-15

The photo-Fenton degradation of paracetamol (PCT) was evaluated using FeSO(4) and the iron complex potassium ferrioxalate (FeOx) as iron source under simulated solar light. The efficiency of the degradation process was evaluated considering the decay of PCT and total organic carbon concentration and the generation of carboxylic acids, ammonium and nitrate, expressed as total nitrogen. The results showed that the degradation was favored in the presence of FeSO(4) in relation to FeOx. The higher concentration of hydroxylated intermediates generated in the presence of FeSO(4) in relation to FeOx probably enhanced the reduction of Fe(III) to Fe(II) improving the degradation efficiency. The degradation products were determined using liquid chromatography electrospray time-of-flight mass spectrometry. Although at different concentrations, the same intermediates were generated using either FeSO(4) or FeOx, which were mainly products of hydroxylation reactions and acetamide. The toxicity of the sample for Vibrio fischeri and Daphnia magna decreased from 100% to less than 40% during photo-Fenton treatment in the presence of both iron species, except for D. magna in the presence of FeOx due to the toxicity of oxalate to this organism. The considerable decrease of the sample toxicity during photo-Fenton treatment using FeSO(4) indicates a safe application of the process for the removal of this pharmaceutical. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Degradation modeling of high temperature proton exchange membrane fuel cells using dual time scale simulation

NASA Astrophysics Data System (ADS)

Pohl, E.; Maximini, M.; Bauschulte, A.; vom Schloß, J.; Hermanns, R. T. E.

2015-02-01

HT-PEM fuel cells suffer from performance losses due to degradation effects. Therefore, the durability of HT-PEM is currently an important factor of research and development. In this paper a novel approach is presented for an integrated short term and long term simulation of HT-PEM accelerated lifetime testing. The physical phenomena of short term and long term effects are commonly modeled separately due to the different time scales. However, in accelerated lifetime testing, long term degradation effects have a crucial impact on the short term dynamics. Our approach addresses this problem by applying a novel method for dual time scale simulation. A transient system simulation is performed for an open voltage cycle test on a HT-PEM fuel cell for a physical time of 35 days. The analysis describes the system dynamics by numerical electrochemical impedance spectroscopy. Furthermore, a performance assessment is performed in order to demonstrate the efficiency of the approach. The presented approach reduces the simulation time by approximately 73% compared to conventional simulation approach without losing too much accuracy. The approach promises a comprehensive perspective considering short term dynamic behavior and long term degradation effects.

[Characterization of a thermophilic Geobacillus strain DM-2 degrading hydrocarbons].

PubMed

Liu, Qing-kun; Wang, Jun; Li, Guo-qiang; Ma, Ting; Liang, Feng-lai; Liu, Ru-lin

2008-12-01

A thermophilic Geobacillus strain DM-2 from a deep-subsurface oil reservoir was investigated on its capability of degrading crude oil under various conditions as well as its characters on degrading hydrocarbons in optimal conditions. The results showed that Geobacillus strain DM-2 was able to degrade crude oil under anoxic wide-range conditions with pH ranging from 4.0 to 10.0, high temperature in the range of 45-70 degrees C and saline concentration ranging from 0.2% to 3.0%. Furthermore, the optimal temperature and pH value for utilizing hydrocarbons by the strain were 60 degrees C and 7.0, respectively. Under such optimal conditions, the strain utilized liquid paraffine emulsified by itself as its carbon source for growth; further analysis by gas chromatography (GC) and infrared absorption spectroscopy demonstrated that it was able to degrade n-alkanes (C14-C30), branched-chain alkanes and aromatic hydrocarbons in crude oil and could also utilize long-chain n-alkanes from C16 to C36, among of which the degradation efficiency of C28 was the highest, up to 88.95%. One metabolite of the strain oxidizing alkanes is fatty acid.While utilizing C16 as carbon source for 5 d, only one fatty acid-acetic acid was detected by HPLC and MS as the product, with the amount of 0.312 g/L, which indicated that it degraded n-alkanes with pathway of inferior terminal oxidation,and then followed by a beta-oxidation pathway. Due to its characters of efficient emulsification, high-performance degradation of hydrocarbons and fatty-acid production under high temperature and anoxic condition, the strain DM-2 may be potentially applied to oil-waste treatment and microbial enhanced heavy oil recovery in extreme conditions.

Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

NASA Astrophysics Data System (ADS)

Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

2017-04-01

Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

Oxidative degradation of nalidixic acid by nano-magnetite via Fe2+/O2-mediated reactions.

PubMed

Ardo, Sandy G; Nélieu, Sylvie; Ona-Nguema, Georges; Delarue, Ghislaine; Brest, Jessica; Pironin, Elsa; Morin, Guillaume

2015-04-07

Organic pollution has become a critical issue worldwide due to the increasing input and persistence of organic compounds in the environment. Iron minerals are potentially able to degrade efficiently organic pollutants sorbed to their surfaces via oxidative or reductive transformation processes. Here, we explored the oxidative capacity of nano-magnetite (Fe3O4) having ∼ 12 nm particle size, to promote heterogeneous Fenton-like reactions for the removal of nalidixic acid (NAL), a recalcitrant quinolone antibacterial agent. Results show that NAL was adsorbed at the surface of magnetite and was efficiently degraded under oxic conditions. Nearly 60% of this organic contaminant was eliminated after 30 min exposure to air bubbling in solution in the presence of an excess of nano-magnetite. X-ray diffraction (XRD) and Fe K-edge X-ray absorption spectroscopy (XANES and EXAFS) showed a partial oxidation of magnetite to maghemite during the reaction, and four byproducts of NAL were identified by liquid chromatography-mass spectroscopy (UHPLC-MS/MS). We also provide evidence that hydroxyl radicals (HO(•)) were involved in the oxidative degradation of NAL, as indicated by the quenching of the degradation reaction in the presence of ethanol. This study points out the promising potentialities of mixed valence iron oxides for the treatment of soils and wastewater contaminated by organic pollutants.

Effective anodic oxidation of naproxen by platinum nanoparticles coated FTO glass.

PubMed

Chin, Ching-Ju Monica; Chen, Tsan-Yao; Lee, Menshan; Chang, Chiung-Fen; Liu, Yu-Ting; Kuo, Yu-Tsun

2014-07-30

This study investigated applications of the electrochemical anodic oxidation process with Pt-FTO and Pt/MWCNTs-FTO glasses as anodes on the treatment of one of the most important emerging contaminants, naproxen. The anodes used in this study have been synthesized using commercial FTO, MWCNTs and Pt nanoparticles (PtNP). XRD patterns of Pt nanoparticles coated on FTO and MWCNTs revealed that MWCNTs can prevent the surface of PtNPs from sintering and thus provide a greater reaction sites density to interact with naproxen, which have also been confirmed by higher degradation and mineralization efficiencies in the Pt/MWCNTs-FTO system. Results from the CV analysis showed that the Pt-FTO and Pt/MWCNTs-FTO electrodes possessed dual functions of decreasing activation energy and interactions between hydroxyl radicals to effectively degrade naproxen. The lower the solution pH value, the better the degradation efficiency. The existence of humic acid indeed inhibited the degradation ability of naproxen due to the competitions in the multiple-component system. The electrochemical degradation processes were controlled by diffusion mechanism and two major intermediates of 2-acetyl-6-methoxynaphthalene and 2-(6-Hydroxy-2-naphthyl)propanoic acid were identified. This study has successfully demonstrated new, easy, flexible and effective anodic materials which can be feasibly applied to the electrochemical oxidation of naproxen. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrolysis and Sulfation Pattern Effects on Release of Bioactive Bone Morphogenetic Protein-2 from Heparin-Based Microparticles.

PubMed

Tellier, Liane E; Miller, Tobias; McDevitt, Todd C; Temenoff, Johnna S

2015-10-28

Glycosaminoglycans (GAGs) such as heparin are promising materials for growth factor delivery due to their ability to efficiently bind positively charged growth factors including bone morphogenetic protein-2 (BMP-2) through their negatively charged sulfate groups. Therefore, the goal of this study was to examine BMP-2 release from heparin-based microparticles (MPs) after first, incorporating a hydrolytically degradable crosslinker and varying heparin content within MPs to alter MP degradation and second, altering the sulfation pattern of heparin within MPs to vary BMP-2 binding and release. Using varied MP formulations, it was found that the time course of MP degradation for 1 wt% heparin MPs was ~4 days slower than 10 wt% heparin MPs, indicating that MP degradation was dependent on heparin content. After incubating 100 ng BMP-2 with 0.1 mg MPs, most MP formulations loaded BMP-2 with ~50% efficiency and significantly more BMP-2 release (60% of loaded BMP-2) was observed from more sulfated heparin MPs (MPs with ~100% and 80% of native sulfation). Similarly, BMP-2 bioactivity in more sulfated heparin MP groups was at least four-fold higher than soluble BMP-2 and less sulfated heparin MP groups, as determined by an established C2C12 cell alkaline phosphatase (ALP) assay. Ultimately, the two most sulfated 10 wt% heparin MP formulations were able to efficiently load and release BMP-2 while enhancing BMP-2 bioactivity, making them promising candidates for future growth factor delivery applications.

Influence of dihydroxybenzenes on paracetamol and ciprofloxacin degradation and iron(III) reduction in Fenton processes.

PubMed

Costa E Silva, Beatriz; de Lima Perini, João Angelo; Nogueira, Raquel F Pupo

2017-03-01

The degradation of paracetamol (PCT) and ciprofloxacin (CIP) was compared in relation to the generation of dihydroxylated products, Fe(III) reduction and reaction rate in the presence of dihydroxybenzene (DHB) compounds, or under irradiation with free iron (Fe 3+ ) or citrate complex (Fecit) in Fenton or photo-Fenton process. The formation of hydroquinone (HQ) was observed only during PCT degradation in the dark, which increased drastically the rate of PCT degradation, since HQ formed was able to reduce Fe 3+ and contributed to PCT degradation efficiency. When HQ was initially added, PCT and CIP degradation rate in the dark was much higher in comparison to the absence of HQ, due to the higher and faster formation of Fe 2+ at the beginning of reaction. In the absence of HQ, no CIP degradation was observed; however, when HQ was added after 30 min, the degradation rate increased drastically. Ten PCT hydroxylated intermediates were identified in the absence of HQ, which could contribute for Fe(III) reduction and consequently to the degradation in a similar way as HQ. During CIP degradation, only one product of hydroxyl radical attack on benzene ring and substitution of the fluorine atom was identified when HQ was added to the reaction medium.

A novel ZrHIO6ṡ4H2O catalyst for degradation of organic dyes at room temperature

NASA Astrophysics Data System (ADS)

Li, Jiayin; Ma, Xinping; Qian, Meifan; Liu, Haoran; Liu, Qiying; Zhao, Caixian; Tian, Li; Chen, Lijuan; Tang, Jianting

It is interesting to obtain catalysts to degrade organic dye pollutants at room temperature for simultaneous purposes of environment-treating and energy-saving. In this work, a novel ZrHIO6ṡ4H2O catalyst was synthesized by reacting ZrO(NO3)2 with H5IO6 in aqueous nitric acid. The catalyst was found effective in degradation of rhodamine B (RhB) or methylene blue (MB) dyes at room temperature without light illumination. We used the ultraviolet-visible (UV-Vis) absorption spectra of dye solution as well as X-ray photoelectron spectroscopy (XPS) of ZrHIO6ṡ4H2O to confirm that the dye degradation was due to its catalytic role. Importantly, the ZrHIO6ṡ4H2O catalyst can be recycled five times without obvious activity loss and it achieved higher mineralization efficiency than the previously reported analogue in the degradation experiments.

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.

Cobalt nanoparticles encapsulated in nitrogen-rich carbon nanotubes as efficient catalysts for organic pollutants degradation via sulfite activation.

PubMed

Wu, Deming; Ye, Peng; Wang, Manye; Wei, Yi; Li, Xiaoxia; Xu, Aihua

2018-06-15

The activation of sulfite by heterogeneous catalysts displays a great potential in the development of new sulfate radials based technologies for wastewater treatment. Herein, cobalt nanoparticles embedded in N-doped carbon nanotubes (Co@NC) were prepared by a simple pyrolysis method. Due to the synergistic effects of the cobalt nanoparticles and N-doped carbon nanotubes, the Co@NC catalyst intrinsically shows an outstanding efficiency, excellent reusability and high stability in the catalytic oxidation of methyl orange (MO) in the presence of sulfite and dioxygen. The structure and efficiency of the catalyst was significantly affected by the content of cobalt and pyrolysis temperature. Several quenching experiments and electron paramagnetic resonance were carried out to investigate the catalytic mechanism. It is found that hydroxyl and sulfate radicals worked together to degrade MO in the system. The formation and decomposition of peroxymonosulfate may be an important route of these reactive radicals production. The effect of different anions, bicarbonate concentration, initial solution pH and dye types on the performance of the catalyst was also studied. This study can open a new approach for design and preparation of encapsulated cobalt in carbon materials as effective catalysts for pollutants degradation via sulfite activation. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of nitrogen doping on the microstructure and visible light photocatalysis of titanate nanotubes by a facile cohydrothermal synthesis via urea treatment

NASA Astrophysics Data System (ADS)

Hu, Cheng-Ching; Hsu, Tzu-Chien; Lu, Shan-Yu

2013-09-01

A facile one-step cohydrothermal synthesis via urea treatment has been adopted to prepare a series of nitrogen-doped titanate nanotubes with highly efficient visible light photocatalysis of rhodamine B, in an effect to identify the effect of nitrogen doping on the photodegradation efficiency. The morphology and microstructure of the thus-prepared N-doped titanates were characterized by nitrogen adsorption/desorption isotherms, transmission electron microscopy, and scanning electron microscopy. With increasing urea loadings, the N-doped titanates change from a porous multi-layer and nanotube-shaped to a dense and aggregated particle-shaped structure, accompanied with reduced specific surface area and pore volume and enhanced pore diameter. Interstitial linkage to titanate via Tisbnd Osbnd N and Tisbnd Nsbnd O is confirmed by X-ray photoelectron spectroscopy. Factors governing the photocatalytic degradation such as the specific surface area of the catalyst and the degradation pathway are analyzed, a mechanistic illustration on the photodegradation is provided, and a 3-stage degradation mechanism is identified. The synergistic contribution due to the enhanced deethylation and chromophore cleavage on rhodamine B molecules and the reduced band gap on the catalyst TiO2 by interstitial nitrogen-doping has been accounted for the high photodegradation efficiency of the N-doped titanate nanotubes.

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.

Different types of degradable vectors from low-molecular-weight polycation-functionalized poly(aspartic acid) for efficient gene delivery.

PubMed

Dou, X B; Hu, Y; Zhao, N N; Xu, F J

2014-03-01

Poly(aspartic acid) (PAsp) has been employed as the potential backbone for the preparation of efficient gene carriers, due to its low cytotoxicity, good biodegradability and excellent biocompatibility. In this work, the degradable linear or star-shaped PBLA was first prepared via ring-opining polymerization of β-benzyl-L-aspartate N-carboxy anhydride (BLA-NCA) initiated by ethylenediamine (ED) or ED-functionalized cyclodextrin cores. Then, PBLA was functionalized via aminolysis reaction with low-molecular-weight poly(2-(dimethylamino)ethyl methacrylate) with one terminal primary amine group (PDMAEMA-NH2), followed by addition of excess ED or ethanolamine (EA) to complete the aminolysis process. The obtained different types of cationic PAsp-based vectors including linear or star PAsp-PDM-NH2 and PAsp-PDM-OH exhibited good condensation capability and degradability, benefiting gene delivery process. In comparison with gold standard polyethylenimine (PEI, ∼ 25 kDa), the cationic PAsp-based vectors, particularly star-shaped ones, exhibited much better transfection performances. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chondroitin Lyase from a Marine Arthrobacter sp. MAT3885 for the Production of Chondroitin Sulfate Disaccharides.

PubMed

Kale, Varsha; Friðjónsson, Ólafur; Jónsson, Jón Óskar; Kristinsson, Hörður G; Ómarsdóttir, Sesselja; Hreggviðsson, Guðmundur Ó

2015-08-01

Chondroitin sulfate (CS) saccharides from cartilage tissues have potential application in medicine or as dietary supplements due to their therapeutic bioactivities. Studies have shown that depolymerized CS saccharides may display enhanced bioactivity. The objective of this study was to isolate a CS-degrading enzyme for an efficient production of CS oligo- or disaccharides. CS-degrading bacteria from marine environments were enriched using in situ artificial support colonization containing CS from shark cartilage as substrate. Subsequently, an Arthrobacter species (strain MAT3885) efficiently degrading CS was isolated from a CS enrichment culture. The genomic DNA from strain MAT3885 was pyro-sequenced by using the 454 FLX sequencing technology. Following assembly and annotation, an orf, annotated as family 8 polysaccharide lyase genes, was identified, encoding an amino acid sequence with a similarity to CS lyases according to NCBI blastX. The gene, designated choA1, was cloned in Escherichia coli and expressed downstream of and in frame with the E. coli malE gene for obtaining a high yield of soluble recombinant protein. Applying a dual-tag system (MalE-Smt3-ChoA1), the MalE domain was separated from ChoA1 with proteolytic cleavage using Ulp1 protease. ChoA1 was defined as an AC-type enzyme as it degraded chondroitin sulfate A, C, and hyaluronic acid. The optimum activity of the enzyme was at pH 5.5-7.5 and 40 °C, running a 10-min reaction. The native enzyme was estimated to be a monomer. As the recombinant chondroitin sulfate lyase (designated as ChoA1R) degraded chondroitin sulfate efficiently compared to a benchmark enzyme, it may be used for the production of chondroitin sulfate disaccharides for the food industry or health-promoting products.

Electrochemical degradation of 5-FU using a flow reactor with BDD electrode: Comparison of two electrochemical systems.

PubMed

Ochoa-Chavez, A S; Pieczyńska, A; Fiszka Borzyszkowska, A; Espinoza-Montero, P J; Siedlecka, E M

2018-06-01

In this study, the electrochemical degradation process of 5-fluorouracil (5-FU) in aqueous media was performed using a continuous flow reactor in an undivided cell (system I), and in a divided cell with a cationic membrane (Nafion ® 424) (system II). In system I, 75% of 5-FU degradation was achieved (50 mg L -1 ) with a applied current density j app  = 150 A m -2 , volumetric flow rate qv = 13 L h -1 , after 6 h of electrolysis (k app  = 0.004 min -1 ). The removal efficiency of 5-FU was higher (95%) when the concentration was 5 mg L -1 under the same conditions. Nitrates (22% of initial amount of N), fluorides (27%) and ammonium (10%) were quantified after 6 h of electrolysis. System II, 77% of 5-FU degradation was achieved (50 mg L -1 ) after 6 h of electrolysis (k app  = 0.004 min -1 ). The degradation rate of 5-FU was complete when the concentration was 5 mg L -1 under the same conditions. Nitrates (29% of initial amount of N), fluorides (25%) and ammonium (5%) were quantified after 6 h of electrolysis. In addition, the main organic byproducts identified by mass spectroscopy were aliphatic compound with carbonyl and carboxyl functionalities. Due to, the mineralization of 5-FU with acceptable efficiency of 88% found in system II (j app of 200 A m -2 ), this system seems to be more promising in the cytostatic drug removal. Moreover the efficiency of 5-FU removal in diluted solutions is better in system II than in system I. Copyright © 2018 Elsevier Ltd. All rights reserved.

Secretion of small proteins is species-specific within Aspergillus sp.

PubMed

Valette, Nicolas; Benoit-Gelber, Isabelle; Falco, Marcos Di; Wiebenga, Ad; de Vries, Ronald P; Gelhaye, Eric; Morel-Rouhier, Mélanie

2017-03-01

Small secreted proteins (SSP) have been defined as proteins containing a signal peptide and a sequence of less than 300 amino acids. In this analysis, we have compared the secretion pattern of SSPs among eight aspergilli species in the context of plant biomass degradation and have highlighted putative interesting candidates that could be involved in the degradative process or in the strategies developed by fungi to resist the associated stress that could be due to the toxicity of some aromatic compounds or reactive oxygen species released during degradation. Among these candidates, for example, some stress-related superoxide dismutases or some hydrophobic surface binding proteins (HsbA) are specifically secreted according to the species . Since these latter proteins are able to recruit lytic enzymes to the surface of hydrophobic solid materials and promote their degradation, a synergistic action of HsbA with the degradative system may be considered and need further investigations. These SSPs could have great applications in biotechnology by optimizing the efficiency of the enzymatic systems for biomass degradation. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

[Degradation of p-nitrophenol by high voltage pulsed discharge and ozone processes].

PubMed

Pan, Li-li; Yan, Guo-qi; Zheng, Fei-yan; Liang, Guo-wei; Fu, Jian-jun

2005-11-01

The vigorous oxidation by ozone and the high energy by pulsed discharge are utilized to degrade the big hazardous molecules. And these big hazardous molecules become small and less hazardous by this process in order to improve the biodegradability. When pH value is 8-9, the concentration of p-nitrophenol solution can be degraded by 96.8% and the degradation efficiency of TOC is 38.6% by ozone and pulsed discharge treatment for 30 mins. The comparison results show that the combination treatment efficiency is higher than the separate, so the combination of ozone and pulsed discharge has high synergism. It is approved that the phenyl degradation efficiency is high and the degradation efficiency of linear molecules is relative low.

Studying the fate of non-volatile organic compounds in a commercial plasma air purifier.

PubMed

Schmid, Stefan; Seiler, Cornelia; Gerecke, Andreas C; Hächler, Herbert; Hilbi, Hubert; Frey, Joachim; Weidmann, Simon; Meier, Lukas; Berchtold, Christian; Zenobi, Renato

2013-07-15

Degradation of non-volatile organic compounds-environmental toxins (methyltriclosane and phenanthrene), bovine serum albumin, as well as bioparticles (Legionella pneumophila, Bacillus subtilis, and Bacillus anthracis)-in a commercially available plasma air purifier based on a cold plasma was studied in detail, focusing on its efficiency and on the resulting degradation products. This system is capable of handling air flow velocities of up to 3.0m s(-1) (3200Lmin(-1)), much higher than other plasma-based reactors described in the literature, which generally are limited to air flow rates below 10Lmin(-1). Mass balance studies consistently indicated a reduction in concentration of the compounds/particles after passage through the plasma air purifier, 31% for phenanthrene, 17% for methyltriclosane, and 80% for bovine serum albumin. L. pneumophila did not survive passage through the plasma air purifier, and cell counts of aerosolized spores of B. subtilis and B. anthracis were reduced by 26- and 15-fold, depending on whether it was run at 10Hz or 50Hz, respectively. However rather than chemical degradation, deposition on the inner surfaces of the plasma air purifier occured. Our interpretation is that putative "degradation" efficiencies were largely due to electrostatic precipitation rather than to decomposition into smaller molecules. Copyright © 2013 Elsevier B.V. All rights reserved.

Device Modeling and Characterization for CIGS Solar Cells

NASA Astrophysics Data System (ADS)

Song, Sang Ho

We studied the way to achieve high efficiency and low cost of CuIn1-xGaxSe2 (CIGS) solar cells. The Fowler-Nordheim (F-N) tunneling currents at low bias decreased the shunt resistances and degraded the fill factor and efficiency. The activation energies of majority traps were directly related with F-N tunneling currents by the energy barriers. Air anneals decreased the efficiency from 7.74% to 5.18% after a 150 °C, 1000 hour anneal. The decrease of shunt resistance due to F-N tunneling and the increase of series resistance degrade the efficiencies of solar cells. Air anneal reduces the free carrier densities by the newly generated Cu interstitial defects (Cui). Mobile Cui defects induce the metastability in CIGS solar cell. Since oxygen atoms are preferred to passivate the Se vacancies thus Cu interstitial defects explains well metastability of CIGS solar cells. Lattice mismatch and misfit stress between layers in CIGS solar cells can explain the particular effects of CIGS solar cells. The misfits of 35.08° rotated (220/204) CIGS to r-plane (102) MoSe2 layers are 1% ˜ -4% lower than other orientation and the lattice constants of two layers in short direction are matched at Ga composition x=0.35. This explains well the preferred orientation and the maximum efficiency of Ga composition effects. Misfit between CIGS and CdS generated the dislocations in CdS layer as the interface traps. Thermionic emission currents due to interface traps limit the open circuit voltage at high Ga composition. The trap densities were calculated by critical thickness and dislocation spacing and the numerical device simulation results were well matched with the experimental results. A metal oxide broken-gap p-n heterojunction is suggested for tunnel junction for multi-junction polycrystalline solar cells and we examined the characteristics of broken-gap tunnel junction by numerical simulation. Ballistic transport mechanism explains well I-V characteristics of broken-gap junction. P-type Cu2O and n-type In2O3 broken-gap heterojunction is effective with the CIGS tandem solar cells. The junction has linear I-V characteristics with moderate carrier concentration (2x1017 cm-3) and the resistance is lower than GaAs tunnel junction. The efficiency of a CGS/CIS tandem solar cells was 24.1% with buffer layers. And no significant degradations are expected due to broken gap junction.

Wastewater treatment by sonophotocatalysis using PEG modified TiO2 film in a circular Photocatalytic-Ultrasonic system.

PubMed

Hu, Xiaohong; Zhu, Qi; Gu, Zhibin; Zhang, Nan; Liu, Na; Stanislaus, Mishma S; Li, Dawei; Yang, Yingnan

2017-05-01

TiO 2 photocatalyst film recently has been utilized as the potential candidate for the wastewater treatment, due to its high stability and low toxicity. In order to further increase the photocatalytic ability and stability, different molecular weight of polyethylene glycol (PEG) were used to modify TiO 2 structure to synthesize porous thin film used in the developed Photocatalytic-Ultrasonic system in this work. The results showed that PEG2000 modified TiO 2 calcinated under 450°C for 2h exhibited the highest photocatalytic activity, attributed to the smallest crystallite size and optimal particle size. Over 95.0% of rhodamine B (Rh B) was photocatalytically degraded by optimized PEG 2000 -TiO 2 film after 60min of UV irradiation, while only about 50.8% of Rh B was decolored over pure TiO 2 film. Furthermore, optimized PEG 2000 -TiO 2 film was used in a circular Photocatalytic-Ultrasonic system, and the obtained synergy (0.6519) of sonophotocatalysis indicated its extremely high efficiency for Rh B degradation. In this Photocatalytic-Ultrasonic system, larger amount of PEG 2000 -TiO 2 coated glass beads, stronger ultrasonic power and longer experimental time could result to higher degradation efficiency of Rh B. In addition, repetitive experiments showed that about 97.2% of Rh B were still degraded in the fifth experiment by sonophotocatalysis using PEG 2000 -TiO 2 film. Therefore, PEG 2000 -TiO 2 film used in Photocatalytic-Ultrasonic system has promising potential for wastewater treatment, due to its excellent photocatalytic activity and high stability. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel method for the synergistic remediation of oil-water mixtures using nanoparticles and oil-degrading bacteria.

PubMed

Alabresm, Amjed; Chen, Yung Pin; Decho, Alan W; Lead, Jamie

2018-07-15

Releases of crude oil and other types of oil from numerous sources can impose catastrophic physical, chemical, and biological effects on aquatic ecosystems. While currently-used oil removal techniques possess many advantages, they have inherent limitations, including low removal efficiencies and waste disposal challenges. The present study quantified the synergistic interactions of polyvinylpyrrolidone (PVP) coated magnetite nanoparticles (NP) and oil-degrading bacteria for enhanced oil removal at the laboratory scale. The results showed that at relatively high oil concentrations (375 mg L -1 ), NP alone could remove approximately 70% of lower-chain alkanes (C9-C22) and 65% of higher-chain (C23-C26), after only 1 h, when magnetic separation of NP was used. Removal efficiency did not increase significantly after that, which was likely due to saturation of the NP with oil. Microbial bioremediation, using strains of oil-degrading bacteria, removed almost zero oil immediately but 80-90% removal after 24-48 h. The combination of NPs and oil-degrading bacterial strains worked effectively to remove essentially 100% of oil within 48 h or less. This was likely due to the sorption of oil components to NPs and their subsequent utilization by bacteria as a joint Fe and C source, although the mechanisms of removal require further testing. Furthermore, results showed that the emission of selected volatile organic compounds (VOCs) and semi volatile organic compounds (SVOCs) were reduced after addition of NPs and bacteria separately. When combined, VOC and SVOC emissions were reduced by up to 80%. Copyright © 2018 Elsevier B.V. All rights reserved.

A hybrid LBG/lattice vector quantizer for high quality image coding

NASA Technical Reports Server (NTRS)

Ramamoorthy, V.; Sayood, K.; Arikan, E. (Editor)

1991-01-01

It is well known that a vector quantizer is an efficient coder offering a good trade-off between quantization distortion and bit rate. The performance of a vector quantizer asymptotically approaches the optimum bound with increasing dimensionality. A vector quantized image suffers from the following types of degradations: (1) edge regions in the coded image contain staircase effects, (2) quasi-constant or slowly varying regions suffer from contouring effects, and (3) textured regions lose details and suffer from granular noise. All three of these degradations are due to the finite size of the code book, the distortion measures used in the design, and due to the finite training procedure involved in the construction of the code book. In this paper, we present an adaptive technique which attempts to ameliorate the edge distortion and contouring effects.

Investigations into B-O defect formation-dissociation in CZ-silicon and their effect on solar cell performance

NASA Astrophysics Data System (ADS)

Basnyat, Prakash M.

About 30% of the total market share of industrial manufacture of silicon solar cells is taken by single crystalline Czochralski (CZ) grown wafers. The efficiency of solar cells fabricated on boron-doped Czochralski silicon degrades due to the formation of metastable defects when excess electrons are created by illumination or minority carrier injection during forward bias. The recombination path can be removed by annealing the cell at about 200° C but recombination returns on exposure to light. Several mono-crystalline and multi-crystalline solar cells have been characterized by methods such as laser beam induced current (LBIC), Four-Probe electrical resistivity etc. to better understand the light induced degradation (LID) effect in silicon solar cells. All the measurements are performed as a function of light soaking time. Annealed states are produced by exposing the cells/wafer to temperature above 200° C for 30 minutes and light soaked state was produced by exposure to 1000 W/m2 light using AM1.5 solar simulator for 72 hours. Dark I-V data are analyzed by a software developed at NREL. This study shows that LID, typically, has two components- a bulk component that arises from boron-oxygen defects and a surface component that appears to be due to the SiNx:H-Si interface. With the analysis of dark saturation current (J02), it is seen that the surface LID increases with an increase in the q/2kT component. Results show that cell performance due to bulk effect is fully recovered upon annealing where as surface LID does not recover fully. This statement is also verified by the study of mc- silicon solar cells. Multi-crystalline silicon solar cell has very low oxygen content and, therefore, recombination sites will not be able to form. This shows that there is no bulk degradation in mc- Si solar cells but they exhibit surface degradation. The results suggest that a typical Cz-silicon solar cell with an initial efficiency of ˜18% could suffer a reduction in efficiency to ˜ 17.5% after the formation of a metastable defect, out of which ˜ 0.4% comes from a bulk effect and ˜0.1% is linked to a surface effect.

Chlorophyll loss associated with heat-induced senescence in bentgrass.

PubMed

Jespersen, David; Zhang, Jing; Huang, Bingru

2016-08-01

Heat stress-induced leaf senescence is characterized by the loss of chlorophyll from leaf tissues. The objectives of this study were to examine genetic variations in the level of heat-induced leaf senescence in hybrids of colonial (Agrostis capillaris)×creeping bentgrass (Agrostis stolonifera) contrasting in heat tolerance, and determine whether loss of leaf chlorophyll during heat-induced leaf senescence was due to suppressed chlorophyll synthesis and/or accelerated chlorophyll degradation in the cool-season perennial grass species. Plants of two hybrid backcross genotypes ('ColxCB169' and 'ColxCB190') were exposed to heat stress (38/33°C, day/night) for 28 d in growth chambers. The analysis of turf quality, membrane stability, photochemical efficiency, and chlorophyll content demonstrated significant variations in the level of leaf senescence induced by heat stress between the two genotypes, with ColXCB169 exhibiting a lesser degree of decline in chlorophyll content, photochemical efficiency and membrane stability than ColXCB190. The assays of enzymatic activity or gene expression of several major chlorophyll-synthesizing (porphobilinogen deaminase, Mg-chelatase, protochlorophyllide-reductase) and chlorophyll-degrading enzymes (chlorophyllase, pheophytinase, and chlorophyll-degrading peroxidase) indicated heat-induced decline in leaf chlorophyll content was mainly due to accelerated chlorophyll degradation, as manifested by increased gene expression levels of chlorophyllase and pheophytinase, and the activity of pheophytinase (PPH), while chlorophyll-synthesizing genes and enzymatic activities were not differentially altered by heat stress in the two genotypes. The analysis of heat-induced leaf senescence of pph mutants of Arabidopsis further confirmed that PPH could be one enzymes that plays key roles in regulating heat-accelerated chlorophyll degradation. Further research on enzymes responsible in part for the loss of chlorophyll during heat-induced senescence could aid in the development of genotypes with stay-green traits either through marker assisted selection or transgenic approaches. Copyright © 2016. Published by Elsevier Ireland Ltd.

Identification of vessel wall degradation in ascending thoracic aortic aneurysms with OCT

PubMed Central

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

2014-01-01

Degradation of the wall of human ascending thoracic aorta has been assessed through Optical Coherence Tomography (OCT). OCT images of the media layer of the aortic wall exhibit micro-structure degradation in case of diseased aortas from aneurysmal vessels. The OCT indicator of degradation depends on the dimension of areas of the media layer where backscattered reflectivity becomes smaller due to a disorder on the morphology of elastin, collagen and smooth muscle cells (SMCs). Efficient pre-processing of the OCT images is required to accurately extract the dimension of degraded areas after an optimized thresholding procedure. OCT results have been validated against conventional histological analysis. The OCT qualitative assessment has achieved a pair sensitivity-specificity of 100%-91.6% in low-high degradation discrimination when a threshold of 4965.88µm2 is selected. This threshold suggests to have physiological meaning. The OCT quantitative evaluation of degradation achieves a correlation of 0.736 between the OCT indicator and the histological score. This in-vitro study can be transferred to the clinical scenario to provide an intraoperative assessment tool to guide cardiovascular surgeons in open repair interventions. PMID:25426332

Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions

PubMed Central

Yin, Penghua; Hu, Zhihao; Song, Xin; Liu, Jianguo; Lin, Na

2016-01-01

Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C–50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO4−• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO4−•, followed by a HF elimination process aided by •OH, which produces one-CF2-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn−1F2n−1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs. PMID:27322298

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.

Extremely high efficient nanoreactor with Au@ZnO catalyst for photocatalysis

NASA Astrophysics Data System (ADS)

Su, Chung-Yi; Yang, Tung-Han; Gurylev, Vitaly; Huang, Sheng-Hsin; Wu, Jenn-Ming; Perng, Tsong-Pyng

2015-10-01

We fabricated a photocatalytic Au@ZnO@PC (polycarbonate) nanoreactor composed of monolayered Au nanoparticles chemisorbed on conformal ZnO nanochannel arrays within the PC membrane. A commercial PC membrane was used as the template for deposition of a ZnO shell into the pores by atomic layer deposition (ALD). Thioctic acid (TA) with sufficient steric stabilization was used as a molecular linker for functionalization of Au nanoparticles in a diameter of 10 nm. High coverage of Au nanoparticles anchored on the inner wall of ZnO nanochannels greatly improved the photocatalytic activity for degradation of Rhodamine B. The membrane nanoreactor achieved 63% degradation of Rhodamine B within only 26.88 ms of effective reaction time owing to its superior mass transfer efficiency based on Damköhler number analysis. Mass transfer limitation can be eliminated in the present study due to extremely large surface-to-volume ratio of the membrane nanoreactor.

Photocatalytic degradation of commercially sourced naphthenic acids by TiO2-graphene composite nanomaterial.

PubMed

Liu, Juncheng; Wang, Lin; Tang, Jingchun; Ma, Jianli

2016-04-01

Naphthenic acids (NAs) are a major contributor to the toxicity in oil sands process-affected water (OSPW), which is produced by hot water extraction of bitumen. NAs are extremely difficult to be degraded due to its complex ring and side chain structure. Photocatalysis is recognized as a promising technology in the removal of refractory organic pollutants. In this work, TiO2-graphene (P25-GR) composites were synthesized by means of solvothermal method. The results showed that P25-GR composite exhibited better photocatalytic activity than pure P25. The removal efficiency of naphthenic acids in acid solution was higher than that in neutral and alkaline solutions. It was the first report ever known on the photodegradation of NAs based on graphene, and this process achieved a higher removal rate than other photocatalysis degradation of NAs in a shorter reaction time. LC/MS analysis showed that macromolecular NAs (carbon number 17-22, z value -2) were easy to be degraded than the micromolecular ones (carbon number 11-16, z value -2). Furthermore, the reactive oxygen species that play the main role in the photocatalysis system were studied. It was found that holes and ·OH were the main reactive species in the UV/P25-GR photocatalysis system. Given the high removal efficiency of refractory organic pollutants and the short degradation time, photodegradation based on composite catalysts has a broad and practical prospect. The study on the photodegradation of commercially sourced NAs may provide a guidance for the degradation of OSPW NAs by this method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hot phonon effect on electron velocity saturation in GaN: A second look

NASA Astrophysics Data System (ADS)

Khurgin, Jacob; Ding, Yujie J.; Jena, Debdeep

2007-12-01

A theoretical model is developed for electron velocity saturation in high power GaN transistors. It is shown that electron velocity at high electric fields is reduced due to heating of electron gas since the high density of nonequilibrium LO phonons cannot efficiently transfer heat to the lattice. However, the resulting degradation of electron velocity is found to be weaker than previously reported. The results are compared with experimental data, and the ways to improve the efficiency of cooling the electron gas to increase the drift velocity are discussed.

Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation.

PubMed

Maleki, Afshin; Safari, Mahdi; Shahmoradi, Behzad; Zandsalimi, Yahya; Daraei, Hiua; Gharibi, Fardin

2015-11-01

In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

Self-organized TiO2 nanotube arrays in the photocatalytic degradation of methylene blue under UV light irradiation

NASA Astrophysics Data System (ADS)

Chung, Eun Hyuk; Baek, Seong Rim; Yu, Seong Mi; Kim, Jong Pil; Hong, Tae Eun; Kim, Hyun Gyu; Bae, Jong-Seong; Jeong, Euh Duck; Khan, F. Nawaz; Jung, Ok-sang

2015-04-01

Nanostructured titanium dioxide (NTiO2) is known to possess efficient photocatalytic activity and to have diverse applications in many fields due to its chemical stability, high surface area/volume ratio, high transmittance, and high refractive index in the visible and the near-ultraviolet regions. These facts prompted us to develop TiO2 nanotube (TiO2 NT) arrays through electrochemical anodic oxidation involving different electrolytes comprised of phosphoric acid — hydrofluoric acid aqueous systems by varying the voltage and the time. The annealing temperature of the nanotubes, TiO2 NTs, were varied to modify the surface morphology and were characterized by using X-ray diffraction and scanning electron microscopy. Scanning electron microscopy and X-ray diffraction results showed that the samples had uniform morphologies and good crystalline structures of the anatase phase at lower annealing temperatures and of the rutile phase at higher annealing temperatures. A secondary-ion mass-spectrometry analysis was used to investigate the surface atoms and to conduct a depth profile analysis of the TiO2 NTs. The efficiency of the photocatalytic activity of the TiO2 NT arrays in degrading methylene blue (MB) was investigated under UV-Vis light irradiation. The maximum photocatalytic activity was achieved for the samples with lower annealing temperatures due to their being in the anatase phase and having a higher surface area and a smaller crystal size, which play important roles in the degradation of organic pollutants.

Mechanism insight of PFOA degradation by ZnO assisted-photocatalytic ozonation: Efficiency and intermediates.

PubMed

Wu, Dan; Li, Xukai; Tang, Yiming; Lu, Ping; Chen, Weirui; Xu, Xiaoting; Li, Laisheng

2017-08-01

Zinc oxide (ZnO) nanorods were prepared by a directly pyrolysis method and employed as catalyst for perfluorooctanoic acid (PFOA) degradation. Comparative experiments were conducted to discuss the catalytic activity and flexibility of ZnO. After ZnO addition, the best PFOA degradation efficiency (70.5%) was achieved by ZnO/UV/O 3 system, only 9.5% by sole ozonation and 18.2% by UV 254 light irradiation. PFOA degradation was sensitive with pH value and temperature. The better PFOA removal efficiency was achieved at acidic condition. A novel relationship was found among PFOA degradation efficiency with hydroxyl radicals and photo-generated holes. Hydroxyl radicals generated on the surfaces of ZnO nanorods played dominant roles in PFOA degradation. PFOA degradation was found to follow the photo-Kolbe reaction mechanism. C 2 -C 7 shorter-chain perfluorocarboxylic acids and fluoride ion were detected as main intermediates during PFOA degradation process. Based on the results, a proposal degradation pathway was raised. Copyright © 2017 Elsevier Ltd. All rights reserved.

Decoupling degradation in exciton formation and recombination during lifetime testing of organic light-emitting devices

NASA Astrophysics Data System (ADS)

Hershey, Kyle W.; Suddard-Bangsund, John; Qian, Gang; Holmes, Russell J.

2017-09-01

The analysis of organic light-emitting device degradation is typically restricted to fitting the overall luminance loss as a function of time or the characterization of fully degraded devices. To develop a more complete understanding of degradation, additional specific data are needed as a function of luminance loss. The overall degradation in luminance during testing can be decoupled into a loss in emitter photoluminescence efficiency and a reduction in the exciton formation efficiency. Here, we demonstrate a method that permits separation of these component efficiencies, yielding the time evolution of two additional specific device parameters that can be used in interpreting and modeling degradation without modification to the device architecture or introduction of any additional post-degradation characterization steps. Here, devices based on the phosphor tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) are characterized as a function of initial luminance and emissive layer thickness. The overall loss in device luminance is found to originate primarily from a reduction in the exciton formation efficiency which is exacerbated in devices with thinner emissive layers. Interestingly, the contribution to overall degradation from a reduction in the efficiency of exciton recombination (i.e., photoluminescence) is unaffected by thickness, suggesting a fixed exciton recombination zone width and degradation at an interface.

Photocatalytic degradation of the diazo dye naphthol blue black in water using MWCNT/Gd,N,S-TiO2 nanocomposites under simulated solar light.

PubMed

Mamba, Gcina; Mbianda, Xavier Yangkou; Mishra, Ajay Kumar

2015-07-01

A simple sol-gel method was employed to prepare gadolinium, nitrogen and sulphur tridoped titania decorated on oxidised multiwalled carbon nanotubes (MWCNT/Gd,N,S-TiO2), using titanium (IV) butoxide and thiourea as titanium and nitrogen and sulphur source, respectively. Samples of varying gadolinium loadings (0.2%, 0.6%, 1.0% and 3.0% Gd3+) relative to titania were prepared to investigate the effect of gadolinium loading and the amounts of carbon nanotubes, nitrogen and sulphur were kept constant for all the samples. Furthermore, the prepared nanocomposites were evaluated for the degradation of naphthol blue black (NBB) in water under simulated solar light irradiation. Higher degradation efficiency (95.7%) was recorded for the MWCNT/Gd,N,S-TiO2 (0.6% Gd) nanocomposites. The higher photocatalytic activity is attributed to the combined effect of improved visible light absorption and charge separation due to the synergistic effect of Gd, MWCNTs, N, S and TiO2. Total organic carbon (TOC) analysis revealed a higher degree of complete mineralisation of naphthol blue black (78.0% TOC removal) which minimises the possible formation of toxic degradation by-products such as the aromatic amines. The MWCNT/Gd,N,S-TiO2 (0.6% Gd) was fairly stable and could be re-used for five times, reaching a maximum degradation efficiency of 91.8% after the five cycles. Copyright © 2015. Published by Elsevier B.V.

Degradation of florfenicol in water by UV/Na2S 2O 8 process.

PubMed

Gao, Yu-Qiong; Gao, Nai-Yun; Deng, Yang; Yin, Da-Qiang; Zhang, Yan-Sen

2015-06-01

UV irradiation-activated sodium persulfate (UV/PS) was studied to degrade florfenicol (FLO), a phenicol antibiotic commonly used in aquaculture, in water. Compared with UV/H2O2 process, UV/PS process achieves a higher FLO degradation efficiency, greater mineralization, and less cost. The quantum yield for direct photolysis of FLO and the second-order rate constant of FLO with sulfate radicals were determined. The effects of various factors, namely PS concentration, anions (NO3 (-), Cl(-), and HCO3 (-)), ferrous ion, and humic acid (HA), on FLO degradation were investigated. The results showed that the pseudo-first-order rate constant increased linearly with increased PS concentration. The tested anions all adversely affected FLO degradation performance with the order of HCO3 (-) > Cl(-) > NO3 (-). Coexisting ferrous ions enhanced FLO degradation at a Fe(2+)/PS molar ratio under 1:1. HA significantly inhibited FLO degradation due to radical scavenging and light-screening effect. Toxicity assessment showed that it is capable of controlling the toxicity for FLO degradation. These findings indicated that UV/PS is a promising technology for water polluted by antibiotics, and the treatment is optimized only after the impacts of water characteristics are carefully considered.

Gas-liquid hybrid discharge-induced degradation of diuron in aqueous solution.

PubMed

Feng, Jingwei; Zheng, Zheng; Luan, Jingfei; Li, Kunquan; Wang, Lianhong; Feng, Jianfang

2009-05-30

Degradation of diuron in aqueous solution by gas-liquid hybrid discharge was investigated for the first time. The effect of output power intensity, pH value, Fe(2+) concentration, Cu(2+) concentration, initial conductivity and air flow rate on the degradation efficiency of diuron was examined. The results showed that the degradation efficiency of diuron increased with increasing output power intensity and increased with decreasing pH values. In the presence of Fe(2+), the degradation efficiency of diuron increased with increasing Fe(2+) concentration. The degradation efficiency of diuron was decreased during the first 4 min and increased during the last 10 min with adding of Cu(2+). Decreasing the initial conductivity and increasing the air flow rate were favorable for the degradation of diuron. Degradation of diuron by gas-liquid hybrid discharge fitted first-order kinetics. The pH value of the solution decreased during the reaction process. Total organic carbon removal rate increased in the presence of Fe(2+) or Cu(2+). The generated Cl(-1), NH(4)(+), NO(3)(-), oxalic acid, acetic acid and formic acid during the degradation process were also detected. Based on the detected Cl(-1) and other intermediates, a possible degradation pathway of diuron was proposed.

Intimate Coupling of Photocatalysis and Biodegradation for Degrading Phenol Using Different Light Types: Visible Light vs UV Light.

PubMed

Zhou, Dandan; Xu, Zhengxue; Dong, Shanshan; Huo, Mingxin; Dong, Shuangshi; Tian, Xiadi; Cui, Bin; Xiong, Houfeng; Li, Tingting; Ma, Dongmei

2015-07-07

Intimate coupling of photocatalysis and biodegradation (ICPB) technology is attractive for phenolic wastewater treatment, but has only been investigated using UV light (called UPCB). We examined the intimate coupling of visible-light-induced photocatalysis and biodegradation (VPCB) for the first time. Our catalyst was prepared doping both of Er(3+) and YAlO3 into TiO2 which were supported on macroporous carriers. The macroporous carriers was used to support for the biofilms as well. 99.8% removal efficiency of phenol was achieved in the VPCB, and this was 32.6% higher than that in the UPCB. Mineralization capability of UPCB was even worse, due to less adsorbable intermediates and cell lysis induced soluble microbial products release. The lower phenol degradation in the UPCB was due to the serious detachment of the biofilms, and then the microbes responsible for phenol degradation were insufficient due to disinfection by UV irradiation. In contrast, microbial communities in the carriers were well protected under visible light irradiation and extracellular polymeric substances secretion was enhanced. Thus, we found that the photocatalytic reaction and biodegradation were intimately coupled in the VPCB, resulting in 64.0% removal of dissolved organic carbon. Therefore, we found visible light has some advantages over UV light in the ICPB technology.

Bioinformatics Analysis and Characterization of Highly Efficient Polyvinyl Alcohol (PVA)-Degrading Enzymes from the Novel PVA Degrader Stenotrophomonas rhizophila QL-P4.

PubMed

Wei, Yahong; Fu, Jing; Wu, Jianying; Jia, Xinmiao; Zhou, Yunheng; Li, Cuidan; Dong, Mengxing; Wang, Shanshan; Zhang, Ju; Chen, Fei

2018-01-01

Polyvinyl alcohol (PVA) is used widely in industry, and associated environmental pollution is a serious problem. Herein, we report a novel, efficient PVA degrader, Stenotrophomonas rhizophila QL-P4, isolated from fallen leaves from a virgin forest in the Qinling Mountains. The complete genome was obtained using single-molecule real-time (SMRT) technology and corrected using Illumina sequencing. Bioinformatics analysis revealed eight PVA/vinyl alcohol oligomer (OVA)-degrading genes. Of these, seven genes were predicted to be involved in the classic intracellular PVA/OVA degradation pathway, and one (BAY15_3292) was identified as a novel PVA oxidase. Five PVA/OVA-degrading enzymes were purified and characterized. One of these, BAY15_1712, a PVA dehydrogenase (PVADH), displayed high catalytic efficiency toward PVA and OVA substrate. All reported PVADHs only have PVA-degrading ability. Most importantly, we discovered a novel PVA oxidase (BAY15_3292) that exhibited higher PVA-degrading efficiency than the reported PVADHs. Further investigation indicated that BAY15_3292 plays a crucial role in PVA degradation in S. rhizophila QL-P4. Knocking out BAY15_3292 resulted in a significant decline in PVA-degrading activity in S. rhizophila QL-P4. Interestingly, we found that BAY15_3292 possesses exocrine activity, which distinguishes it from classic PVADHs. Transparent circle experiments further proved that BAY15_3292 greatly affects extracellular PVA degradation in S. rhizophila QL-P4. The exocrine characteristics of BAY15_3292 facilitate its potential application to PVA bioremediation. In addition, we report three new efficient secondary alcohol dehydrogenases (SADHs) with OVA-degrading ability in S. rhizophila QL-P4; in contrast, only one OVA-degrading SADH was reported previously. IMPORTANCE With the widespread application of PVA in industry, PVA-related environmental pollution is an increasingly serious issue. Because PVA is difficult to degrade, it accumulates in aquatic environments and causes chronic toxicity to aquatic organisms. Biodegradation of PVA, as an economical and environment-friendly method, has attracted much interest. To date, effective and applicable PVA-degrading bacteria/enzymes have not been reported. Herein, we report a new efficient PVA degrader ( S. rhizophila QL-P4) that has five PVA/OVA-degrading enzymes with high catalytic efficiency, among which BAY15_1712 is the only reported PVADH with both PVA- and OVA-degrading abilities. Importantly, we discovered a novel PVA oxidase (BAY15_3292) that is not only more efficient than other reported PVA-degrading PVADHs but also has exocrine activity. Overall, our findings provide new insight into PVA-degrading pathways in microorganisms and suggest S. rhizophila QL-P4 and its enzymes have the potential for application to PVA bioremediation to reduce or eliminate PVA-related environmental pollution. Copyright © 2017 American Society for Microbiology.

Automated array assembly task development of low-cost polysilicon solar cells

NASA Technical Reports Server (NTRS)

Jones, G. T.

1980-01-01

Development of low cost, large area polysilicon solar cells was conducted in this program. Three types of polysilicon materialk were investigated. A theoretical and experimenal comparison between single crystal silicon and polysilicon solar cell efficiency was performed. Significant electrical performance differences were observed between types of wafer material, i.e. fine grain and coarse grain polysilicon and single crystal silicon. Efficiency degradation due to grain boundaries in fin grain and coarse grain polysilicon was shown to be small. It was demonstrated that 10 percent efficient polysilicon solar cells can be produced with spray on n+ dopants. This result fulfills an important goal of this project, which is the production of batch quantity of 10 percent efficient polysilicon solar cells.

Acetaminophen degradation by electro-Fenton and photoelectro-Fenton using a double cathode electrochemical cell.

PubMed

de Luna, Mark Daniel G; Veciana, Mersabel L; Su, Chia-Chi; Lu, Ming-Chun

2012-05-30

Acetaminophen is a widely used drug worldwide and is one of the most frequently detected in bodies of water making it a high priority trace pollutant. This study investigated the applicability of the electro-Fenton and photoelectro-Fenton processes using a double cathode electrochemical cell in the treatment of acetaminophen containing wastewater. The Box-Behnken design was used to determine the effects of initial Fe(2+) and H(2)O(2) concentrations and applied current density. Results showed that all parameters positively affected the degradation efficiency of acetaminophen with the initial Fe(2+) concentration being the most significant parameter for both processes. The acetaminophen removal efficiency for electro-Fenton was 98% and chemical oxygen demand (COD) removal of 43% while a 97% acetaminophen removal and 42% COD removal were observed for the photoelectro-Fenton method operated at optimum conditions. The electro-Fenton process was only able to obtain 19% total organic carbon (TOC) removal while the photoelectro-Fenton process obtained 20%. Due to negligible difference between the treatment efficiencies of the two processes, the electro-Fenton method was proven to be more economically advantageous. The models obtained from the study were applicable to a wide range of acetaminophen concentrations and can be used in scale-ups. Thirteen different types of intermediates were identified and a degradation pathway was proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

Novel integrated electrodialysis/electro-oxidation process for the efficient degradation of 2,4-dichlorophenoxyacetic acid.

PubMed

Raschitor, A; Llanos, J; Cañizares, P; Rodrigo, M A

2017-09-01

This work presents a novel approach of wastewater treatment technology that consists of a combined electrodialysis/electro-oxidation process, specially designed to allow increasing the efficiency in the oxidation of ionic organic pollutants contained in diluted waste. Respect to conventional electrolysis, the pollutant is simultaneously concentrated and oxidized, enhancing the performance of the cell due to the higher concentration achieved in the nearness of the anode. A proof of concept is tested with the ionic pesticide 2,4-D (2,4-dichlorophenoxyacetic acid) and results show that the efficiency of this new technology overcomes that electrolysis by more than double, regardless the supporting electrolyte used (either NaCl or Na 2 SO 4 ). Moreover, the removal rate of 2,4-D when using NaCl was found to be more efficient, due to the best performance of the electrode material selected (DSA ® ) towards the formation of oxidants in chloride supporting electrolyte. These results open the way for overcoming the efficiency limitations of electrochemical treatment processes for the treatment of solutions with low concentrated ionic pollutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of different factors on photodefluorination of perfluorinated compounds by hydrated electrons in organo-montmorillonite system.

PubMed

Tian, Haoting; Gu, Cheng

2018-01-01

Perfluorinated compounds (PFCs) are considered as the most recalcitrant organic contaminants. Our previous research has shown that PFCs can be completely defluorinated in the UV/organoclay/3-indole acetic acid system, however, the factors that could affect the degradation of PFCs, are still not clear. In this study, we further investigated the effect of different indole derivatives and organo-modified montmorillonite on the degradation of perfluooctanoic acid (PFOA). Based on multiple linear regression analysis, our results clearly indicate that hydrated electron yields of indole derivatives, adsorption of PFOA and indole derivatives on organo-montmorillonite contributed independently to the degradation of PFOA. In addition, the results also show that the presence of humic substance (even at 10 mg C L -1 ) would not significantly suppress the degradation process due to the strong adsorption of humic substance on the organo-montmorillonite surface. This study would provide more information to design an efficient and environment-friendly system for degradation of PFCs, and this technique will have great potential for treatment of persistent contaminants under mild reaction conditions. Copyright © 2017. Published by Elsevier Ltd.

Photocatalytic Degradation of 4-Nitrophenol by C, N-TiO2: Degradation Efficiency vs. Embryonic Toxicity of the Resulting Compounds

NASA Astrophysics Data System (ADS)

Osin, Oluwatomiwa A.; Yu, Tianyu; Cai, Xiaoming; Jiang, Yue; Peng, Guotao; Cheng, Xiaomei; Li, Ruibin; Qin, Yao; Lin, Sijie

2018-06-01

The photocatalytic activity of TiO2 based photocatalysts can be improved by structural modification and elemental doping. In this study, through rational design, one type of carbon and nitrogen co-doped TiO2 (C, N-TiO2) photocatalyst with mesoporous structure was synthesized with improved photocatalytic activity in degrading 4-nitrophenol under simulated sunlight irradiation. The photocatalytic degradation efficiency of the C, N-TiO2 was much higher than the anatase TiO2 (A-TiO2) based on absorbance and HPLC analyses. Moreover, using zebrafish embryos, we showed that the intermediate degradation compounds generated by photocatalytic degradation of 4-nitrophenol had higher toxicity than the parent compound. A repeated degradation process was necessary to render complete degradation and non-toxicity to the zebrafish embryos. Our results demonstrated the importance of evaluating the photocatalytic degradation efficiency in conjunction with the toxicity assessment of the degradation compounds.

Photocatalytic Degradation of 4-Nitrophenol by C, N-TiO2: Degradation Efficiency vs. Embryonic Toxicity of the Resulting Compounds.

PubMed

Osin, Oluwatomiwa A; Yu, Tianyu; Cai, Xiaoming; Jiang, Yue; Peng, Guotao; Cheng, Xiaomei; Li, Ruibin; Qin, Yao; Lin, Sijie

2018-01-01

The photocatalytic activity of TiO 2 based photocatalysts can be improved by structural modification and elemental doping. In this study, through rational design, one type of carbon and nitrogen co-doped TiO 2 (C, N-TiO 2 ) photocatalyst with mesoporous structure was synthesized with improved photocatalytic activity in degrading 4-nitrophenol under simulated sunlight irradiation. The photocatalytic degradation efficiency of the C, N-TiO 2 was much higher than the anatase TiO 2 (A-TiO 2 ) based on absorbance and HPLC analyses. Moreover, using zebrafish embryos, we showed that the intermediate degradation compounds generated by photocatalytic degradation of 4-nitrophenol had higher toxicity than the parent compound. A repeated degradation process was necessary to render complete degradation and non-toxicity to the zebrafish embryos. Our results demonstrated the importance of evaluating the photocatalytic degradation efficiency in conjunction with the toxicity assessment of the degradation compounds.

Study on degrading graphene oxide in wastewater under different conditions for developing an efficient and economical degradation method.

PubMed

Li, Ting; Zhang, Chao-Zhi; Gu, Chengyue

2017-12-01

With popular application of graphene and graphene oxide (GO), they have been discharged into water. Graphene and GO harm organisms. However, an efficient and economical method for removing graphene and GO in wastewater has seldom been reported. Graphene can be oxidized by hydrogen peroxide to give GO; therefore, degradation of graphene oxide is an important step in the procedure of removal of graphene from water. In this paper, GO degradation via photo-Fenton reaction under different conditions was carried out. Experimental results suggested that GO in wastewater can be efficiently and economically degraded into carbon dioxide and H 2 O when pH value is 3, concentration of H 2 O 2 and FeCl 3 are 35 mM and 5 ppm, respectively. Degradation mechanism of GO was suggested based on UV-vis absorption spectra, scanning electron microscopy, X-ray diffraction and liquid chromatography-mass spectra data of degradation intermediates. This paper suggests an efficient and economical degradation way of GO in wastewater.

Degradation of Chlorophenols by Alcaligenes eutrophus JMP134(pJP4) in Bleached Kraft Mill Effluent

PubMed Central

Valenzuela, J.; Bumann, U.; Cespedes, R.; Padilla, L.; Gonzalez, B.

1997-01-01

The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degradation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semicontinuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichlorophenoxyacetate (400 ppm) or 2,4,6-trichlorophenol (40 to 100 ppm) were extensively degraded (70 to 100%). In short-term batch incubations, indigenous microorganisms were unable to degrade such of compounds. Degradation of 2,4,6-trichlorophenol by strain JMP134 was significantly lower at 200 to 400 ppm of compound. This strain was also able to degrade 2,4-dichlorophenoxyacetate, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-trichlorophenol when bleached Kraft mill effluent was amended with mixtures of these compounds. On the other hand, the chlorophenol concentration and the indigenous microorganisms inhibited the growth and survival of the strain in short-term incubations. In long-term (>1-month) incubations, strain JMP134 was unable to maintain a large, stable population, although extensive 2,4,6-trichlorophenol degradation was still observed. The latter is probably due to acclimation of the indigenous microorganisms to degrade 2,4,6-trichlorophenol. Acclimation was observed only in long-term, semicontinuous microcosms. PMID:16535488

Degradation of Silicone Encapsulants in CPV Optics

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

Cai, Can; Miller, David C.; Tappan, Ian A.

High efficiency multijunction solar cells in terrestrial concentrator photovoltaic (CPV) modules are becoming an increasingly cost effective and viable option in utility scale power generation. As with other utility scale photovoltaics, CPV modules need to guarantee operational lifetimes of at least 25 years. The reliability of optical elements in CPV modules poses a unique materials challenge due to the increased UV irradiance and enhanced temperature cycling associated with concentrated solar flux. The polymeric and thin film materials used in the optical elements are especially susceptible to UV damage, diurnal temperature cycling and active chemical species from the environment. We usedmore » fracture mechanics approaches to study the degradation modes including: the adhesion between the encapsulant and the cell or secondary optical element; and the cohesion of the encapsulant itself. Understanding the underlying mechanisms of materials degradation under elevated stress conditions is critical for commercialization of CPV technology and can offer unique insights into degradation modes in similar encapsulants used in other photovoltaic modules.« less

Degradation of Silicone Encapsulants in CPV Optics: Preprint

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

Miller, David C.; Tappan, Ian A.; Cai, Can

High efficiency multijunction solar cells in terrestrial concentrator photovoltaic (CPV) modules are becoming an increasingly cost effective and viable option in utility scale power generation. As with other utility scale photovoltaics, CPV modules need to guarantee operational lifetimes of at least 25 years. The reliability of optical elements in CPV modules poses a unique materials challenge due to the increased UV irradiance and enhanced temperature cycling associated with concentrated solar flux. The polymeric and thin film materials used in the optical elements are especially susceptible to UV damage, diurnal temperature cycling and active chemical species from the environment. We usedmore » fracture mechanics approaches to study the degradation modes including: the adhesion between the encapsulant and the cell or secondary optical element; and the cohesion of the encapsulant itself. Understanding the underlying mechanisms of materials degradation under elevated stress conditions is critical for commercialization of CPV technology and can offer unique insights into degradation modes in similar encapsulants used in other photovoltaic modules.« less

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.

A case study of in situ oil contamination in a mangrove swamp (Rio De Janeiro, Brazil).

PubMed

Brito, Elcia M S; Duran, Robert; Guyoneaud, Rémy; Goñi-Urriza, Marisol; García de Oteyza, T; Crapez, Miriam A C; Aleluia, Irene; Wasserman, Julio C A

2009-08-01

Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation.

Ground-water quality in the Santa Rita, Buellton, and Los Olivos hydrologic subareas of the Santa Ynez River basin, Santa Barbara County, California

USGS Publications Warehouse

Hamlin, S.N.

1985-01-01

Groundwater quality in the upper Santa Ynez River Valley in Santa Barbara County has degraded due to both natural and anthropogenic causes. The semiarid climate and uneven distribution of rainfall has limited freshwater recharge and caused salt buildup in water supplies. Tertiary rocks supply mineralized water. Agricultural activities (irrigation return flow containing fertilizers and pesticides, cultivation, feedlot waste disposal) are a primary cause of water quality degradation. Urban development, which also causes water quality degradation (introduced contaminants, wastewater disposal, septic system discharge, and land fill disposal of waste), has imposed stricter requirements on water supply quality. A well network was designed to monitor changes in groundwater quality related to anthropogenic activities. Information from this network may aid in efficient management of the groundwater basins as public water supplies, centered around three basic goals. First is to increase freshwater recharge to the basins by conjunctive surface/groundwater use and surface-spreading techniques. Second is to optimize groundwater discharge by efficient timing and spacing of pumping. Third is to control and reduce sources of groundwater contamination by regulating wastewater quality and distribution and, preferably, by exporting wastewaters from the basin. (USGS)

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

TiO2 supported on reed straw biochar as an adsorptive and photocatalytic composite for the efficient degradation of sulfamethoxazole in aqueous matrices.

PubMed

Zhang, Hanyu; Wang, Zhaowei; Li, Ruining; Guo, Jialei; Li, Yan; Zhu, Junmin; Xie, Xiaoyun

2017-10-01

Heterogeneous photocatalysis namely titanium dioxide supported on reed straw biochar (acid pre-treated) (TiO 2 /pBC) was synthesized by sol-gel method. The morphology, surface area and structure of TiO 2 /pBC were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD). Low calcination condition maintained the structure of biochar completely and prevented the agglomeration of TiO 2 particles. Due to the combination of adsorption and photocatalysis, TiO 2 /pBC performed higher removal efficiency of sulfamethoxazole (SMX) than pure TiO 2 powder under UV light irradiation. The photocatalytic degradation (PCD) of SMX was also studied with the water collected from the Yellow River. Three high concentration inorganic anions (Cl - , NO 3 - , SO 4 2- ) of the river exerted certain degree of detrimental effects on the contaminant degradation. TiO 2 /pBC showed stable photocatalytic activity after five sequential PCD cycles. The biochar was able to promote further PCD on TiO 2 by adsorbing SMX and intermediates thereby prolonging the separation lifetime of electrons (e - ) and valence band hole (h + ). The transformation intermediates of SMX were identified and three possible degradation reactions of hydroxylation, opening of isoxazole ring and cleavage of SN bond might occur during the PCD of SMX. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of bisphenol A and acute toxicity reduction by different thermo-tolerant ascomycete strains isolated from arid soils.

PubMed

Mtibaà, Rim; Olicón-Hernández, Dario Rafael; Pozo, Clementina; Nasri, Moncef; Mechichi, Tahar; González, Jesus; Aranda, Elisabet

2018-07-30

Four different laccase-producing strains were isolated from arid soils and used for bisphenol A (BPA) degradation. These strains were identified as Chaetomium strumarium G5I, Thielavia arenaria CH9, Thielavia arenaria HJ22 and Thielavia arenaria SM1(III) by internal transcribed spacer 5.8 S rDNA analysis. Residual BPA was evaluated by HPLC analysis during 48 h of incubation. A complete removal of BPA was observed by the whole cell fungal cultures within different times, depending on each strain. C. strumarium G5I was the most efficient degrader, showing 100% of removal within 8 h of incubation. The degradation of BPA was accompanied by the production of laccase and dye decolorizing peroxidase (DyP) under degradation conditions. The presence of aminobenzotriazole (ABT) as an inhibitor of cytochrome P450s monooxygenases (CYP) demonstrated a slight decrease in BPA removal rate, suggesting the effective contribution of CYP in the conversion. The great involvement of laccase in BPA transformation together with cell-associated enzymes, such as CYP, was supported by the identification of hydroxylated metabolites by ultra-high performance liquid chromatography-mass spectroscopy (UHPLC-MS). The metabolic pathway of BPA transformation was proposed based on the detected metabolites. The acute toxicity of BPA and its products was investigated and showed a significant reduction, except for T. arenaria SM1(III) that did not caused reduction of toxicity (IC 50 < 8%), possibly due to the presence of toxic metabolites. The results of the present study point out the potential application of the isolated ascomycetes in pollutant removal processes, especially C. strumarium G5I as an efficient degrader of BPA. Copyright © 2018 Elsevier Inc. All rights reserved.

The correlation between structural properties, geometrical features, and photoactivity of freestanding TiO2 nanotubes in comparative degradation of 2,4-dichlorophenol and methylene blue

NASA Astrophysics Data System (ADS)

Vahabzadeh Pasikhani, Javad; Gilani, Neda; Ebrahimian Pirbazari, Azadeh

2018-02-01

Freestanding TiO2 nanotubes (FSNTs) with various physical dimensions were fabricated by two-step anodization process with different voltages and anodization times. The detachment method employed in this study involved voltage reduction at the end of the second step and ultrasonic chemical treatment. The results demonstrated that this detachment method is a beneficial technique to create thin open-mouthed and closed-end FSNTs (with lengths of 6-14 μm). Moreover, the influences of anodization conditions on photocatalytic activity, structural properties and geometrical features of FSNTs in comparative degradation of two non-colored (2,4-dichlorophenol) and colored (methylene blue) pollutants were investigated. Findings revealed that the quantity of the photocatalyst utilized is an effective parameter and using the optimum weight (10 mg/100 ml of 2,4-dichlorophenol) could increase the efficiency of the process up to 21%. Further, the results demonstrated that if equal optimum weights of FSNTs are chosen, decreases in voltage and anodization time significantly influence the structural properties, geometrical features, and photodegradation efficiency. The enhancement achieved in the degradation of both 2,4-dichlorophenol and methylene blue using the nanotubes with the shortest diameter (54 nm) and length (6.5 μm), which possess the lowest porosity (0.5) and also the highest surface area (0.53 m2 g-1), nanotubes’ density (19 cm2 cm-2) and wall thickness to length ratio (2). In addition, the results obtained indicated that the degradation reactions follow first-order kinetics in the degradation of the both pollutants. The apparent degradation rate constant of methylene blue was approximately 1.2 times greater than of the 2,4-dichlorophenol due to the negative charge of the nanotubes’ surface and electrostatic adsorptions.

Revealing potential functions of VBNC bacteria in polycyclic aromatic hydrocarbons biodegradation.

PubMed

Su, X M; Bamba, A M; Zhang, S; Zhang, Y G; Hashmi, M Z; Lin, H J; Ding, L X

2018-04-01

The bioremediation of polycyclic aromatic hydrocarbon (PAH)-contaminated sites is not running smoothly, because of the lower activity of PAH-degrading bacteria in actual bioremediation applications. The phenomenon of "viable but nonculturable" (VBNC) state may be a main limiting factor for their poor biodegradation capabilities of PAHs. Due to their abilities of entering into the VBNC state, most of bacterial populations with PAH-degradation potential remain unculturable. Resuscitation of VBNC bacteria will enhance the degradation capability of indigenous bacteria which will eventually obtain their better capabilities in environmental bioremediation. Although evidences have been presented indicating that resuscitation of VBNC bacteria in polychlorinated biphenyl (PCB)-contaminated environments not only significantly enhanced PCB degradation, but also obtained novel highly efficient PCB-degrading bacteria, scanty information is available on the VBNC bacteria in PAH-contaminated sites. VBNC bacteria, as a vast majority of potential microbial resource could be the repository of novel highly efficient PAH-biodegraders. Therefore, studies need to be done on resuscitation of VBNC bacteria to overcome key bottlenecks in bioremediation of PAH-contaminated sites. This mini-review provides a new insight into the potential functions of VBNC bacteria in PAHs biodegradation. As the vast majority microbial resource, viable but nonculturable (VBNC) bacteria, which showed their potential functions in polycyclic aromatic hydrocarbons (PAHs) biodegradation, can be of great significance in environmental bioremediation. It is therefore important to resuscitate VBNC bacteria for their better capabilities. Meanwhile, preventing the indigenous functional community from entering into the VBNC state will also maintain the high activity of PAH-degrading bacteria in actual bioremediation applications. Undoubtedly, much more work needs to be done to reveal indigenous micro-organisms in the VBNC state from the perspective of environmental functions. © 2018 The Society for Applied Microbiology.

An in vivo model to assess magnesium alloys and their biological effect on human bone marrow stromal cells.

PubMed

Yoshizawa, Sayuri; Chaya, Amy; Verdelis, Kostas; Bilodeau, Elizabeth A; Sfeir, Charles

2015-12-01

Magnesium (Mg) alloys have many unique qualities which make them ideal candidates for bone fixation devices, including biocompatibility and degradation in vivo. Despite a rise in Mg alloy production and research, there remains no standardized system to assess their degradation or biological effect on human stem cells in vivo. In this study, we developed a novel in vivo model to assess Mg alloys for craniofacial and orthopedic applications. Our model consists of a collagen sponge seeded with human bone marrow stromal cells (hBMSCs) around a central Mg alloy rod. These scaffolds were implanted subcutaneously in mice and analyzed after eight weeks. Alloy degradation and biological effect were determined by microcomputed tomography (microCT), histological staining, and immunohistochemistry (IHC). MicroCT showed greater volume loss for pure Mg compared to AZ31 after eight weeks in vivo. Histological analysis showed that hBMSCs were retained around the Mg implants after 8 weeks. Furthermore, immunohistochemistry showed the expression of dentin matrix protein 1 and osteopontin around both pure Mg and AZ31 with implanted hBMSCs. In addition, histological sections showed a thin mineral layer around all degrading alloys at the alloy-tissue interface. In conclusion, our data show that degrading pure Mg and AZ31 implants are cytocompatible and do not inhibit the osteogenic property of hBMSCs in vivo. These results demonstrate that this model can be used to efficiently assess the biological effect of corroding Mg alloys in vivo. Importantly, this model may be modified to accommodate additional cell types and clinical applications. Magnesium (Mg) alloys have been investigated as ideal candidates for bone fixation devices due to high biocompatibility and degradation in vivo, and there is a growing need of establishing an efficient in vivo material screening system. In this study, we assessed degradation rate and biological effect of Mg alloys by transplanting Mg alloy rod with human bone marrow stromal cells seeded on collagen sponge subcutaneously in mice. After 8 weeks, samples were analyzed by microcomputed tomography and histological staining. Our data show that degrading Mg alloys are cytocompatible and do not inhibit the osteogenic property of hBMSCs in vivo. These results demonstrate that this model can be used to efficiently assess the biological effect of corroding Mg alloys in vivo. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Graphene as a thin-film catalyst booster: graphene-catalyst interface plays a critical role.

PubMed

Chae, Sieun; Jin Choi, Won; Sang Chae, Soo; Jang, Seunghun; Chang, Hyunju; Lee, Tae Il; Kim, Youn Sang; Lee, Jeong-O

2017-12-08

Due to its extreme thinness, graphene can transmit some surface properties of its underlying substrate, a phenomenon referred to as graphene transparency. Here we demonstrate the application of the transparency of graphene as a protector of thin-film catalysts and a booster of their catalytic efficiency. The photocatalytic degradation of dye molecules by ZnO thin films was chosen as a model system. A ZnO thin film coated with monolayer graphene showed greater catalytic efficiency and long-term stability than did bare ZnO. Interestingly, we found the catalytic efficiency of the graphene-coated ZnO thin film to depend critically on the nature of the bottom ZnO layer; graphene transferred to a relatively rough, sputter-coated ZnO thin film showed rather poor catalytic degradation of the dye molecules while a smooth sol-gel-synthesized ZnO covered with monolayer graphene showed enhanced catalytic degradation. Based on a systematic investigation of the interface between graphene and ZnO thin films, we concluded the transparency of graphene to be critically dependent on its interface with a supporting substrate. Graphene supported on an atomically flat substrate was found to efficiently transmit the properties of the substrate, but graphene suspended on a substrate with a rough nanoscale topography was completely opaque to the substrate properties. Our experimental observations revealed the morphology of the substrate to be a key factor affecting the transparency of graphene, and should be taken into account in order to optimally apply graphene as a protector of catalytic thin films and a booster of their catalysis.

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

Tang, Boxin; Schneiderman, Deborah K.; Zare Bidoky, Fazel

We have designed printable, biocompatible, and degradable ion gels by combining a novel ABA triblock aliphatic polyester, poly(ε-decalactone)-b-poly(dl-lactide)-b-poly(ε-decalactone), and a low toxicity ionic liquid, 1-butyl-1-methylpyrrolidinium bistrifluoromethanesulfonylimide ([P14][TFSI]). Due to the favorable compatibility between amorphous poly(dl-lactide) and [P14][TFSI] and the insolubility of the poly(ε-decalactone), the triblock polymer forms self-assembled micellar cross-links similar to thermoplastic elastomers, which ensures similar processing conditions and mechanical robustness during the fabrication of printed electrolyte-gated organic transistor devices. Additionally, the ester backbone in the polymer structure enables efficient hydrolytic degradation of these ion gels compared to those made previously using carbon-backbone polymers.

Fenton-like oxidation of 2,4-DCP in aqueous solution using iron-based nanoparticles as the heterogeneous catalyst.

PubMed

Li, Renchao; Gao, Ying; Jin, Xiaoying; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2015-01-15

In this report, various iron-based nanoparticles (nZVI, n-Ni/Fe, n-Pd/Fe) were used for both heterogeneous Fenton oxidation of 2,4-dichlorophenol (2,4-DCP) and reductive dechlorination of 2,4-DCP in order to understand their roles in the Fenton oxidation and the reductive degradation of 2,4-DCP. The dechlorination efficiency of 2,4-DCP using nZVI, n-Ni/Fe, n-Fe/Pd and Fe(2)(+) was 6.48%, 6.80%, 15.95%, 5.02%, while Fenton oxidation efficiency of 2,4-DCP was 57.87%, 34.23%, 27.94%, 19.61% after 180 min, respectively. The new findings included a higher dechlorination using n-Fe/Pd due to Pd effective catalysis and the effective heterogeneous Fenton oxidation using nZVI depending on reductive dechlorination and heterogeneous Fenton oxidation occurs simultaneously. However, nZVI as the potential catalyst for heterogeneous Fenton was observed, and SEM, EDS and XRD demonstrate that change on the nZVI surface occurred due to the Fe(2+) leaching, and Total Organic Carbon (TOC) (30.71%) shows that 2,4-DCP was degraded. Furthermore, the experiment indicates that the pH values and concentration of 2,4-DCP significantly impacted on the heterogeneous Fenton oxidation of 2,4-DCP and the data fits well with the pseudo first-order kinetic model, which was a diffusion-controlled reaction. Finally, a possible mechanism for degradation of 2,4-DCP was proposed. Copyright © 2014 Elsevier Inc. All rights reserved.

Natural soil mediated photo Fenton-like processes in treatment of pharmaceuticals: Batch and continuous approach.

PubMed

Changotra, Rahil; Rajput, Himadri; Dhir, Amit

2017-12-01

This paper manifests the potential viability of soil as a cost-free catalyst in photo-Fenton-like processes for treating pharmaceuticals at large scale. Naturally available soil without any cost intensive modification was utilized as a catalyst to degrade pharmaceuticals, specifically ornidazole (ORZ) and ofloxacin (OFX). Soil was characterized and found enriched with various iron oxides like hematite, magnetite, goethite, pyrite and wustite, which contributes toward enhanced dissolution of Fe 3+ than Fe 2+ in the aqueous solution resulting in augmented rate of photo-Fenton reaction. The leached iron concentration in solution was detected during the course of experiments. The degradation of ORZ and OFX was assessed in solar induced batch experiments using H 2 O 2 as oxidant and 95% ORZ and 92% OFX removal was achieved. Elevated efficiencies were achieved due to Fe 2+ /Fe 3+ cycling, producing more hydroxyl radical leading to the existence of homogeneous and heterogeneous reactions simultaneously. The removal efficiency of solar photo-Fenton like process was also compared to photo-Fenton process with different irradiation sources (UV-A and UV-B) and were statistically analysed. Continuous-scale studies were conducted employing soil either in the form of soil beads or as a thin layer spread on the surface of baffled reactor. Soil beads were found to have satisfactory reusability and stability. 84 and 79% degradation of ORZ and OFX was achieved using soil as thin layer while with soil beads 71 and 68% degradation, respectively. HPLC and TOC study confirmed the efficient removal of both the compounds. Toxicity assessment demonstrates the inexistence of toxic intermediates during the reaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of clofibric acid in acidic aqueous medium by electro-Fenton and photoelectro-Fenton.

PubMed

Sirés, Ignasi; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric

2007-01-01

Acidic aqueous solutions of clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid), the bioactive metabolite of various lipid-regulating drugs, have been degraded by indirect electrooxidation methods such as electro-Fenton and photoelectro-Fenton with Fe(2+) as catalyst using an undivided electrolytic cell with a Pt anode and an O(2)-diffusion cathode able to electrogenerate H(2)O(2). At pH 3.0 about 80% of mineralization is achieved with the electro-Fenton method due to the efficient production of oxidant hydroxyl radical from Fenton's reaction between Fe(2+) and H(2)O(2), but stable Fe(3+) complexes are formed. The photoelectro-Fenton method favors the photodecomposition of these species under UVA irradiation, reaching more than 96% of decontamination. The mineralization current efficiency increases with rising metabolite concentration up to saturation and with decreasing current density. The photoelectro-Fenton method is then viable for treating acidic wastewaters containing this pollutant. Comparative degradation by anodic oxidation (without Fe(2+)) yields poor decontamination. Chloride ion is released during all degradation processes. The decay kinetics of clofibric acid always follows a pseudo-first-order reaction, with a similar rate constant in electro-Fenton and photoelectro-Fenton that increases with rising current density, but decreases at greater metabolite concentration. 4-Chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol, along with carboxylic acids such as 2-hydroxyisobutyric, tartronic, maleic, fumaric, formic and oxalic, are detected as intermediates. The ultimate product is oxalic acid, which forms very stable Fe(3+)-oxalato complexes under electro-Fenton conditions. These complexes are efficiently photodecarboxylated in photoelectro-Fenton under the action of UVA light.

Effect of loading types on performance characteristics of a trickle-bed bioreactor and biofilter during styrene/acetone vapor biofiltration.

PubMed

Halecky, Martin; Paca, Jan; Kozliak, Evguenii; Jones, Kim

2016-07-02

A 2:1 (w/w) mixture of styrene (STY) and acetone (AC) was subjected to lab-scale biofiltration under varied loading in both a trickle bed reactor (TBR) and biofilter (BF) to investigate substrate interactions and determine the limits of biofiltration efficiency of typical binary air pollutant mixtures containing both hydrophobic and polar components. A comparison of the STY/AC mixture degradation in the TBR and BF revealed higher pollutant removal efficiencies and degradation rates in the TBR, with the pollutant concentrations increasing up to the overloading limit. The maximum styrene degradation rates were 12 and 8 gc m(-3) h(-1) for the TBR and BF, respectively. However, the order of performance switched in favor of the BF when the loading was conducted by increasing air flow rate while keeping the inlet styrene concentration (Cin) constant in contrast to loading by increasing Cin. This switch may be due to a drastic difference in the effective surface area between these two reactors, so the biofilter becomes the reactor of choice when the rate-limiting step switches from biochemical processes to mass transfer by changing the loading mode. The presence of acetone in the mixture decreased the efficiency of styrene degradation and its degradation rate at high loadings. When the overloading was lifted by lowering the pollutant inlet concentrations, short-term back-stripping of both substrates in both reactors into the outlet air was observed, with a subsequent gradual recovery taking several hours and days in the BF and TBR, respectively. Removal of excess biomass from the TBR significantly improved the reactor performance. Identification of the cultivable strains, which was performed on Day 763 of continuous operation, showed the presence of 7 G(-) bacteria, 2 G(+) bacteria and 4 fungi. Flies and larvae of Lycoriella nigripes survived half a year of the biofilter operation by feeding on the biofilm resulting in the maintenance of a nearly constant pressure drop.

Visible light driven photocatalytic degradation of rhodamine B using Mg doped cobalt ferrite spinel nanoparticles synthesized by microwave combustion method

NASA Astrophysics Data System (ADS)

Sundararajan, M.; John Kennedy, L.; Nithya, P.; Judith Vijaya, J.; Bououdina, M.

2017-09-01

Co1-xMgxFe2O4 (0≤x≤0.5) spinel nanoparticles were synthesized by a simple microwave combustion method. The characterization of the samples were performed using X-ray diffraction (XRD) analysis, scanning electron (SEM) microscopy, energy dispersive X-ray (EDX) analysis, UV-visible and diffuse reflectance (DRS) spectroscopy, photoluminescence (PL) spectroscopy, Fourier transformed infrared (FT-IR) spectroscopy and vibrating sample magnetometry (VSM) analysis. The XRD patterns indicate the formation of cubic inverse spinel structure. The calculated average crystallite size using Debye Scherrer's equation is found to be around 46-38 nm. The morphology of spinel nanoparticles was observed from SEM images and the elemental mapping of magnesium doped cobalt ferrite was obtained by using energy dispersive X-ray technique. Optical studies were carried out for the deeper understanding of the conduction band (CB) and valence band (VB) edges of the synthesized nanoparticles. The intrinsic stretching vibrations of Fe3+-O2- in tetrahedral sites leads to the appearance of IR band at around 573 cm-1. The magnetic properties such as remanence magnetization (Mr), coercivity (Hc) and saturation magnetization (Ms) were calculated from the hysteresis curves. The maximum photocatalytic degradation efficiency for Co0.6Mg0.4Fe2O4 is around (99.5%) when compared to that of CoFe2O4 whose efficiency is around (73.0%). The improvement in photocatalytic degradation efficiency is due to the effective separation and prevention of electron-hole pair recombination. The R2 values for the first order rate kinetics are found to be better than R2 values for the second order rate kinetics and this proves that photocatalytic degradation of RhB dye follows first order kinetics. The probable mechanism for the photocatalytic degradation of RhB dye is proposed.

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

PubMed

Vanek, T; Silva, A; Halecky, M; Paca, J; Ruzickova, I; Kozliak, E; Jones, K

2017-07-29

The ability of a bubble column reactor (BCR) to biodegrade a mixture of styrene and acetone vapors was evaluated to determine the factors limiting the process efficiency, with a particular emphasis on the presence of degradation intermediates and oxygen levels. The results obtained under varied loadings and ratios were matched with the dissolved oxygen levels and kinetics of oxygen mass transfer, which was assessed by determination of k L a coefficients. A 1.5-L laboratory-scale BCR was operated under a constant air flow of 1.0 L.min -1 , using a defined mixed microbial population as a biocatalyst. Maximum values of elimination capacities/maximum overall specific degradation rates of 75.5 gC.m -3 .h -1 /0.197 gC.gdw -1 .h -1 , 66.0 gC.m -3 .h -1 /0.059 gC.gdw -1 .h -1 , and 45.8 gC.m -3 .h -1 /0.027 gC.gdw -1 .h -1 were observed for styrene/acetone 2:1, styrene-rich and acetone-rich mixtures, respectively, indicating significant substrate interactions and rate limitation by biological factors. The BCR removed both acetone and styrene near-quantitatively up to a relatively high organic load of 50 g.m -3 .h -1 . From this point, the removal efficiencies declined under increasing loading rates, accompanied by a significant drop in the dissolved oxygen concentration, showing a process transition to oxygen-limited conditions. However, the relatively efficient pollutant removal from air continued, due to significant oxygen mass transfer, up to a threshold loading rate when the accumulation of acetone and degradation intermediates in the aqueous medium became significant. These observations demonstrate that oxygen availability is the limiting factor for efficient pollutant degradation and that accumulation of intermediates may serve as an indicator of oxygen limitation. Microbial (activated sludge) analyses revealed the presence of amoebae and active nematodes that were not affected by variations in operational conditions.

Synergistic enzymatic and microbial lignin conversion

DOE PAGES

Zhao, Cheng; Xie, Shangxian; Pu, Yunqiao; ...

2015-10-02

We represent the utilization of lignin for fungible fuels and chemicals and it's one of the most imminent challenges in modern biorefineries. However, bioconversion of lignin is highly challenging due to its recalcitrant nature as a phenolic heteropolymer. This study addressed the challenges by revealing the chemical and biological mechanisms for synergistic lignin degradation by a bacterial and enzymatic system, which significantly improved lignin consumption, cell growth and lipid yield. The Rhodococcus opacus cell growth increased exponentially in response to the level of laccase treatment, indicating the synergy between laccase and bacterial cells in lignin degradation. Other treatments like ironmore » and hydrogen peroxide showed limited impact on cell growth. Chemical analysis of lignin under various treatments further confirmed the synergy between laccase and cells at the chemical level. 31P nuclear magnetic resonance (NMR) suggested that laccase, R. opacus cell and Fenton reaction reagents promoted the degradation of different types of lignin functional groups, elucidating the chemical basis for the synergistic effects. 31P NMR further revealed that laccase treatment had the most significant impact for degrading the abundant chemical groups. The results were further confirmed by the molecular weight analysis and lignin quantification by the Prussian blue assay. The cell–laccase fermentation led to a 17-fold increase of lipid production. Overall, the study indicated that laccase and R. opacus can synergize to degrade lignin efficiently, likely through rapid utilization of monomers generated by laccase to promote the reaction toward depolymerization. The study provided a potential path for more efficient lignin conversion and development of consolidated lignin conversion.« less

Synergistic enzymatic and microbial lignin conversion

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

Zhao, Cheng; Xie, Shangxian; Pu, Yunqiao

We represent the utilization of lignin for fungible fuels and chemicals and it's one of the most imminent challenges in modern biorefineries. However, bioconversion of lignin is highly challenging due to its recalcitrant nature as a phenolic heteropolymer. This study addressed the challenges by revealing the chemical and biological mechanisms for synergistic lignin degradation by a bacterial and enzymatic system, which significantly improved lignin consumption, cell growth and lipid yield. The Rhodococcus opacus cell growth increased exponentially in response to the level of laccase treatment, indicating the synergy between laccase and bacterial cells in lignin degradation. Other treatments like ironmore » and hydrogen peroxide showed limited impact on cell growth. Chemical analysis of lignin under various treatments further confirmed the synergy between laccase and cells at the chemical level. 31P nuclear magnetic resonance (NMR) suggested that laccase, R. opacus cell and Fenton reaction reagents promoted the degradation of different types of lignin functional groups, elucidating the chemical basis for the synergistic effects. 31P NMR further revealed that laccase treatment had the most significant impact for degrading the abundant chemical groups. The results were further confirmed by the molecular weight analysis and lignin quantification by the Prussian blue assay. The cell–laccase fermentation led to a 17-fold increase of lipid production. Overall, the study indicated that laccase and R. opacus can synergize to degrade lignin efficiently, likely through rapid utilization of monomers generated by laccase to promote the reaction toward depolymerization. The study provided a potential path for more efficient lignin conversion and development of consolidated lignin conversion.« less

Microbial Consortium with High Cellulolytic Activity (MCHCA) for Enhanced Biogas Production

PubMed Central

Poszytek, Krzysztof; Ciezkowska, Martyna; Sklodowska, Aleksandra; Drewniak, Lukasz

2016-01-01

The use of lignocellulosic biomass as a substrate in agricultural biogas plants is very popular and yields good results. However, the efficiency of anaerobic digestion, and thus biogas production, is not always satisfactory due to the slow or incomplete degradation (hydrolysis) of plant matter. To enhance the solubilization of the lignocellulosic biomass various physical, chemical and biological pretreatment methods are used. The aim of this study was to select and characterize cellulose-degrading bacteria, and to construct a microbial consortium, dedicated for degradation of maize silage and enhancing biogas production from this substrate. Over 100 strains of cellulose-degrading bacteria were isolated from: sewage sludge, hydrolyzer from an agricultural biogas plant, cattle slurry and manure. After physiological characterization of the isolates, 16 strains (representatives of Bacillus, Providencia, and Ochrobactrum genera) were chosen for the construction of a Microbial Consortium with High Cellulolytic Activity, called MCHCA. The selected strains had a high endoglucanase activity (exceeding 0.21 IU/mL CMCase activity) and a wide range of tolerance to various physical and chemical conditions. Lab-scale simulation of biogas production using the selected strains for degradation of maize silage was carried out in a two-bioreactor system, similar to those used in agricultural biogas plants. The obtained results showed that the constructed MCHCA consortium is capable of efficient hydrolysis of maize silage, and increases biogas production by even 38%, depending on the inoculum used for methane fermentation. The results in this work indicate that the mesophilic MCHCA has a great potential for application on industrial scale in agricultural biogas plants. PMID:27014244

Effect of geochemical properties on degradation of trichloroethylene by stabilized zerovalent iron nanoparticle with Na-acrylic copolymer.

PubMed

Chen, Meng-yi; Su, Yuh-fan; Shih, Yang-hsin

2014-11-01

Stable nanoscale zero-valent iron (NZVI) particles have been developed to remediate chlorinated compounds. The degradation kinetics and efficiency of trichloroethylene (TCE) by a commercial stabilized NZVI with Na-acrylic copolymer (acNZVI) were investigated and compared with those by laboratory-synthesized NZVI and carboxymethyl cellulose (CMC)-stabilized NZVI particles. Results show that the degradation of TCE by acNZVI was faster than that by NZVI and CMC-NZVI. Increase in temperature enhanced the degradation rate and efficiency of TCE with acNZVI. The activation energy of TCE degradation by acNZVI was estimated to be 23 kJ/mol. The degradation rate constants of TCE decreased from 0.064 to 0.026 min(-1) with decrease in initial pH from 9.03 to 4.23. Common groundwater anions including NO3(-), Cl(-), HCO3(-), and SO4(2-) inhibited slightly the degradation efficiencies of TCE by acNZVI. The Na-acrylic copolymer-stabilized NZVI, which exhibited high degradation kinetics and efficiency, could be a good remediation agent for chlorinated organic compounds. Copyright © 2014 Elsevier Ltd. All rights reserved.

Degradation of PPCPs in activated sludge from different WWTPs in Denmark.

PubMed

Chen, Xijuan; Vollertsen, Jes; Nielsen, Jeppe Lund; Dall, Agnieszka Gieraltowska; Bester, Kai

2015-12-01

Pharmaceuticals and Personal care products (PPCPs) are often found in effluents from wastewater treatment plants (WWTPs) due to insufficient removal during wastewater treatment processes. To understand the factors affecting the removal of PPCPs in classical activated sludge WWTPs, the present study was performed to assess the removal of frequently occurring pharmaceuticals (Naproxen, Fenoprofen, Ketoprofen, Dichlofenac, Carbamazepine) and the biocide Triclosan in activated sludge from four different Danish WWTPs. The respective degradation constants were compared to operational parameters previous shown to be of importance for degradation of micropollutants such as biomass concentration, and sludge retention time (SRT). The most rapid degradation, was observed for NSAID pharmaceuticals (55-90% for Fenoprofen, 77-94% for Ketoprofen and 46-90% for Naproxen), followed by Triclosan (61-91%), while Dichlofenac and Carbamazepine were found to be persistent in the systems. Degradation rate constants were calculated as 0.0026-0.0407 for NSAID pharmaceuticals and 0.0022-0.0065 for triclosan. No relationships were observed between degradation rates and biomass concentrations in the diverse sludges. However, for the investigated PPCPs, the optimal SRT was within 14-20 days (for these values degradation of these PPCPs was the most efficient). Though all of these parameters influence the degradation rate, none of them seems to be overall decisive. These observations indicate that the biological composition of the sludge is more important than the design parameters of the respective treatment plant.

Evaluation of fuel cell system efficiency and degradation at development and during commercialization

NASA Astrophysics Data System (ADS)

Gemmen, R. S.; Johnson, C. D.

Two primary parameters stand out for characterizing fuel cell system performance. The first and most important parameter is system efficiency. This parameter is relatively easy to define, and protocols for its assessment are already available. Another important parameter yet to be fully considered is system degradation. Degradation is important because customers desire to know how long their purchased fuel cell unit will last. The measure of degradation describes this performance factor by quantifying, for example, how the efficiency of the unit degrades over time. While both efficiency and degradation concepts are readily understood, the coupling between these two parameters must also be understood so that proper testing and evaluation of fuel cell systems is achieved. Tests not properly performed, and results not properly understood, may result in improper use of the evaluation data, producing improper R&D planning decisions and financial investments. This paper presents an analysis of system degradation, recommends an approach to its measurement, and shows how these two parameters are related and how one can be "traded-off" for the other.

Efficient photocatalytic degradation of perfluorooctanoic acid by a wide band gap p-block metal oxyhydroxide InOOH

NASA Astrophysics Data System (ADS)

Xu, Jingjing; Wu, Miaomiao; Yang, Jingwen; Wang, Zhengmei; Chen, Mindong; Teng, Fei

2017-09-01

In this work, we prepared a new wide band gap semiconductor, p-block metal oxyhydroxide InOOH, which exhibits efficient activity for perfluorooctanoic acid (PFOA) degradation under mild conditions and UV light irradiation. The apparent rate constant for PFOA degradation by InOOH is 27.6 times higher than that for P25 titania. Results show that ionized PFOA (C7F15COO-) can be adsorbed much more efficiently on the surface of InOOH than P25. Then, the adsorbed C7F15COO- can be decomposed directly by photo-generated holes to form C7F15COOrad radicals. This process is the key step for the photocalytic degradation of PFOA. Major degradation intermediates, fluoride ions and perfluorinated carboxylic acids (PFCAs) with shorter chain lengths were detected during PFOA degradation. A possible pathway for photocatalytic degradation of PFOA is proposed based on the experimental results. Therefore, this studies indicates a potential new material and method for the efficient treatment of PFCA pollutants under mild conditions.

Inhibition of citral degradation in an acidic aqueous environment by polyoxyethylene alkylether surfactants.

PubMed

Maswal, Masrat; Dar, Aijaz Ahmad

2013-06-15

Citral is a flavour component widely used in food and cosmetic industries, but is chemically unstable and degrades over time in aqueous solutions due to acid-catalysed and oxidative reactions leading to loss of desirable flavour. The present study reveals the effect of non-ionic micellar solutions of Brij30 and Brij35 on the extent of solubilisation and stabilisation of citral. The rate of chemical degradation of citral in acidic aqueous solutions was found to be highest, which was subsequently reduced significantly within these studied surfactant systems, suggesting protection of citral from an acidic environment once it is incorporated into the micelles. The work concludes that polyoxyethylene alkylether surfactants with lower HLB value, less dense hydrophilic corona and more hydrophobic core volume are efficient in solubilising and stabilising citral against an acidic environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Synthesis of metal free ultrathin graphitic carbon nitride sheet for photocatalytic dye degradation of Rhodamine B under visible light irradiation

NASA Astrophysics Data System (ADS)

Rahman, Shakeelur; Momin, Bilal; Higgins M., W.; Annapure, Uday S.; Jha, Neetu

2018-04-01

In recent times, low cost and metal free photocatalyts driven under visible light have attracted a lot of interest. One such photo catalyst researched extensively is bulk graphitic carbon nitride sheets. But the low surface area and weak mobility of photo generated electrons limits its photocatalytic performance in the visible light spectrum. Here we present the facile synthesis of ultrathin graphitic carbon nitride using a cost effective melamine precursor and its application in highly efficient photocatalytic dye degradation of Rhodamine B molecules. Compared to bulk graphitic carbon nitride, the synthesized ultrathin graphitic carbon nitride shows an increase in surface area, a a decrease in optical band gap and effective photogenerated charge separation which facilitates the harvest of visible light irradiation. Due to these optimal properties of ultrathin graphitic carbon nitride, it shows excellent photocatalytic activity with photocatalytic degradation of about 95% rhodamine B molecules in 1 hour.

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.

[Progress on biodegradation of polylactic acid--a review].

PubMed

Li, Fan; Wang, Sha; Liu, Weifeng; Chen, Guanjun

2008-02-01

Polylactic acid is a high molecular-weight polyester made from renewable resources such as corn or starch. It is a promising biodegradable plastic due to its mechanical properties, biocompatibility and biodegradability. To achieve natural recycling of polylactic acid, relative microorganisms and the underlying mechanisms in the biodegradation has become an important issue in biodegradable materials. Up to date, most isolated microbes capable of degrading polylactic acid belong to actinomycetes. Proteases secreted by these microorganisms are responsible for the degradation. However, subtle differences exist between these polylactic acid degrading enzymes and typical proteases with respect to substrate binding and catalysis. Amino acids relative to catalysis are postulated to be highly plastic allowing their catalytic hydrolysis of polylactic acid. In this paper we reviewed current studies on biodegradation of polylactic acid concerning its microbial, enzymatic reactions and the possible mechanisms. We also discussed the probability of biologically recycling PLA by applying highly efficient strains and enzymes.

Degradation of selected organophosphate pesticides in wastewater by dielectric barrier discharge plasma.

PubMed

Hu, Yingmei; Bai, Yanhong; Yu, Hu; Zhang, Chunhong; Chen, Jierong

2013-09-01

In this paper, degradation of selected organophosphate pesticides (dichlorvos and dimethoate) in wastewater by dielectric barrier discharge plasma (DBD) was studied. DBD parameters, i.e. discharge powers and air-gap distances, differently affect their degradation efficiency. The results show that better degradation efficiency is obtained with a higher discharge power and a shorter air-gap distance. The effect of radical intervention degradation was also investigated by adding radical scavenger (tert-butyl alcohol) to the pesticide solution during the experiments. The result shows that the degradation efficiency is restrained in the presence of radical scavenger. It clearly demonstrates that hydroxyl radicals are most likely the main driver for degradation process. Moreover, the kinetics indicate that the disappearance rate of pesticides follows the first-order rate law when the initial concentration of the solution is low, but shifts to zero-order at a higher initial concentration.

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

PubMed

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

2014-08-30

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

The engineered biofiltration system

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

Pisotti, D.A.

1997-12-31

For years, biofiltration has meant compost, peat, bark, leave mulch, or any combination of these as the substrate to house microorganisms. This has lead to a number of operational and maintenance problems, including: compaction, channeling, anaerobic zones, dry spots, pressure drop, and media degradation. All of these cause reduced efficiency and increased maintenance and increased operational costs. For these reasons inert media, including plastic beads and low grade carbons have been added to the media for buffering capacity, resists compaction, channeling and to increase efficiency. This has led to search for a more reliable and sturdy media. The media themore » authors chose was activated carbon. Pelletized activated carbon was the ideal candidate due to its uniform size and shape, its inherent hardness, adsorptive capacity, and its ability to withstand microbial degradation. The pressure drop of the system will remain constant after microbial growth occurs, due to the ability to wash the media bed. Carbon allows for the removal of excess biomass which can not be performed on organic media, this is one of the problems leading to media degradation, too many microbes and not enough food (i.e. VOCs). Carbon also allows for spike or increased loads to be treated without performance suffering. Carbon also has tremendous surface area, which allows more microorganisms to be present in a smaller volume, therefore reducing the overall size of the biofilter vessel. This paper will discuss further the findings of a pilot test that was performed using activated carbon as the media for microbial growth. This paper will show the performance of the carbon based biofilter system with respect to pressure drop, residence time, removal efficiency, microbial populations, temperature, moisture, and water requirements. The pilot unit is 350 acfm and operated for 4 months on an air stream in which the contaminant concentrations varied greatly every few minutes.« less

Highly-reliable operation of 638-nm broad stripe laser diode with high wall-plug efficiency for display applications

NASA Astrophysics Data System (ADS)

Yagi, Tetsuya; Shimada, Naoyuki; Nishida, Takehiro; Mitsuyama, Hiroshi; Miyashita, Motoharu

2013-03-01

Laser based displays, as pico to cinema laser projectors have gathered much attention because of wide gamut, low power consumption, and so on. Laser light sources for the displays are operated mainly in CW, and heat management is one of the big issues. Therefore, highly efficient operation is necessitated. Also the light sources for the displays are requested to be highly reliable. 638 nm broad stripe laser diode (LD) was newly developed for high efficiency and highly reliable operation. An AlGaInP/GaAs red LD suffers from low wall plug efficiency (WPE) due to electron overflow from an active layer to a p-cladding layer. Large optical confinement factor (Γ) design with AlInP cladding layers is adopted to improve the WPE. The design has a disadvantage for reliable operation because the large Γ causes high optical density and brings a catastrophic optical degradation (COD) at a front facet. To overcome the disadvantage, a window-mirror structure is also adopted in the LD. The LD shows WPE of 35% at 25°C, highest record in the world, and highly stable operation at 35°C, 550 mW up to 8,000 hours without any catastrophic optical degradation.

Microbial keratinases: industrial enzymes with waste management potential.

PubMed

Verma, Amit; Singh, Hukum; Anwar, Shahbaz; Chattopadhyay, Anirudha; Tiwari, Kapil K; Kaur, Surinder; Dhilon, Gurpreet Singh

2017-06-01

Proteases are ubiquitous enzymes that occur in various biological systems ranging from microorganisms to higher organisms. Microbial proteases are largely utilized in various established industrial processes. Despite their numerous industrial applications, they are not efficient in hydrolysis of recalcitrant, protein-rich keratinous wastes which result in environmental pollution and health hazards. This paved the way for the search of keratinolytic microorganisms having the ability to hydrolyze "hard to degrade" keratinous wastes. This new class of proteases is known as "keratinases". Due to their specificity, keratinases have an advantage over normal proteases and have replaced them in many industrial applications, such as nematicidal agents, nitrogenous fertilizer production from keratinous waste, animal feed and biofuel production. Keratinases have also replaced the normal proteases in the leather industry and detergent additive application due to their better performance. They have also been proved efficient in prion protein degradation. Above all, one of the major hurdles of enzyme industrial applications (cost effective production) can be achieved by using keratinous waste biomass, such as chicken feathers and hairs as fermentation substrate. Use of these low cost waste materials serves dual purposes: to reduce the fermentation cost for enzyme production as well as reducing the environmental waste load. The advent of keratinases has given new direction for waste management with industrial applications giving rise to green technology for sustainable development.

Polysaccharide-thickened aqueous fluoride solutions for rapid destruction of the nerve agent VX. Introducing the opportunity for extensive decontamination scenarios.

PubMed

Elias, Shlomi; Saphier, Sigal; Columbus, Ishay; Zafrani, Yossi

2014-01-01

Among the chemical warfare agents, the extremely toxic nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is a target of high importance in the development of decontamination methods, due to its indefinite persistence on common environmental surfaces. Liquid decontaminants are mostly characterized by high corrosivity, usually offer poor coverage, and tend to flow and accumulate in low areas. Therefore, the development of a noncorrosive decontaminant, sufficiently viscous to resist dripping from the contaminated surface, is necessary. In the present paper we studied different polysaccharides-thickened fluoride aqueous solutions as noncorrosive decontaminants for rapid and efficient VX degradation to the nontoxic product EMPA (ethyl methylphosphonic acid). Polysaccharides are environmentally benign, natural, and inexpensive. Other known decontaminants cannot be thickened by polysaccharides, due to the sensitivity of the latter toward basic or oxidizing agents. We found that the efficiency of VX degradation in these viscous solutions in terms of kinetics and product identity is similar to that of KF aqueous solutions. Guar gum (1.5 wt %) with 4 wt % KF was chosen for further evaluation. The benign nature, rheological properties, adhering capabilities to different surfaces, and decontamination from a porous matrix were examined. This formulation showed promising properties for implementation as a spray decontaminant for common and sensitive environmental surfaces.

Exploitation of Trametes versicolor for bioremediation of endocrine disrupting chemicals in bioreactors

PubMed Central

Sannia, Giovanni; Raganati, Francesca; Olivieri, Giuseppe; Marzocchella, Antonio; Schlosser, Dietmar

2017-01-01

Endocrine disrupting chemicals (EDCs) are environmental contaminants causing increasing concerns due to their toxicity, persistence and ubiquity. In the present study, degradative capabilities of Trametes versicolor, Pleurotus ostreatus and Phanerochaete chrysosporium to act on five EDCs, which represent different classes of chemicals (phenols, parabens and phthalate) and were first applied as single compounds, were assessed. T. versicolor was selected due to its efficiency against target EDCs and its potentialities were exploited against a mixture of EDCs in a cost-effective bioremediation process. A fed-batch approach as well as a starvation strategy were applied in order to reduce the need for input of ‘fresh’ biomass, and avoid the requirement for external nutrients. The fungus was successfully operated in two different bioreactors over one week. Semi-batch cultures were carried out by daily adding a mixture of EDCs to the bioreactors in a total of five consecutive degradation cycles. T. versicolor was able to efficiently remove all compounds during each cycle converting up to 21 mg L-1 day-1 of the tested EDCs. The maintained ability of T. versicolor to remove EDCs without any additional nutrients represents the main outcome of this study, which enables to forecast its application in a water treatment process. PMID:28575092

Exploitation of Trametes versicolor for bioremediation of endocrine disrupting chemicals in bioreactors.

PubMed

Pezzella, Cinzia; Macellaro, Gemma; Sannia, Giovanni; Raganati, Francesca; Olivieri, Giuseppe; Marzocchella, Antonio; Schlosser, Dietmar; Piscitelli, Alessandra

2017-01-01

Endocrine disrupting chemicals (EDCs) are environmental contaminants causing increasing concerns due to their toxicity, persistence and ubiquity. In the present study, degradative capabilities of Trametes versicolor, Pleurotus ostreatus and Phanerochaete chrysosporium to act on five EDCs, which represent different classes of chemicals (phenols, parabens and phthalate) and were first applied as single compounds, were assessed. T. versicolor was selected due to its efficiency against target EDCs and its potentialities were exploited against a mixture of EDCs in a cost-effective bioremediation process. A fed-batch approach as well as a starvation strategy were applied in order to reduce the need for input of 'fresh' biomass, and avoid the requirement for external nutrients. The fungus was successfully operated in two different bioreactors over one week. Semi-batch cultures were carried out by daily adding a mixture of EDCs to the bioreactors in a total of five consecutive degradation cycles. T. versicolor was able to efficiently remove all compounds during each cycle converting up to 21 mg L-1 day-1 of the tested EDCs. The maintained ability of T. versicolor to remove EDCs without any additional nutrients represents the main outcome of this study, which enables to forecast its application in a water treatment process.

The complexities of hydrolytic enzymes from the termite digestive system.

PubMed

Saadeddin, Anas

2014-06-01

The main challenge in second generation bioethanol production is the efficient breakdown of cellulose to sugar monomers (hydrolysis). Due to the recalcitrant character of cellulose, feedstock pretreatment and adapted hydrolysis steps are needed to obtain fermentable sugar monomers. The conventional industrial production process of second-generation bioethanol from biomass comprises several steps: thermochemical pretreatment, enzymatic hydrolysis and sugar fermentation. This process is undergoing continuous optimization in order to increase the bioethanol yield and reduce the economic cost. Therefore, the discovery of new enzymes with high lignocellulytic activity or new strategies is extremely important. In nature, wood-feeding termites have developed a sophisticated and efficient cellulose degrading system in terms of the rate and extent of cellulose hydrolysis and exploitation. This system, which represents a model for digestive symbiosis has attracted the attention of biofuel researchers. This review describes the termite digestive system, gut symbionts, termite enzyme resources, in vitro studies of isolated enzymes and lignin degradation in termites.

Efficient ASK-assisted system for expression and purification of plant F-box proteins.

PubMed

Li, Haiou; Yao, Ruifeng; Ma, Sui; Hu, Shuai; Li, Suhua; Wang, Yupei; Yan, Chun; Xie, Daoxin; Yan, Jianbin

2017-11-01

Ubiquitin-mediated protein degradation plays an essential role in plant growth and development as well as responses to environmental and endogenous signals. F-box protein is one of the key components of the SCF (SKP1-CUL1-F-box protein) E3 ubiquitin ligase complex, which recruit specific substrate proteins for subsequent ubiquitination and 26S proteasome-mediated degradation to regulate developmental processes and signaling networks. However, it is not easy to obtain purified F-box proteins with high activity due to their unstable protein structures. Here, we found that Arabidopsis SKP-like proteins (ASKs) can significantly improve soluble expression of F-box proteins and maintain their bioactivity. We established an efficient ASK-assisted method to express and purify plant F-box proteins. The method meets a broad range of criteria required for the biochemical analysis or protein crystallization of plant F-box proteins. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Measuring Road Network Vulnerability with Sensitivity Analysis

PubMed Central

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

2017-01-01

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

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

PubMed

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

2017-07-31

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

Differential accumulation of photosynthetic proteins regulates diurnal photochemical adjustments of PSII in common fig (Ficus carica L.) leaves.

PubMed

Mlinarić, Selma; Antunović Dunić, Jasenka; Skendrović Babojelić, Martina; Cesar, Vera; Lepeduš, Hrvoje

2017-02-01

Molecular processes involved in photosystem II adaptation of woody species to diurnal changes in light and temperature conditions are still not well understood. Regarding this, here we investigated differences between young and mature leaves of common fig (Ficus carica L.) in photosynthetic performance as well as accumulation of the main photosynthetic proteins: light harvesting complex II, D1 protein and Rubisco large subunit. Investigated leaf types revealed different adjustment mechanisms to keep effective photosynthesis. Rather stable diurnal accumulation of light harvesting complex II in mature leaves enabled efficient excitation energy utilization (negative L-band) what triggered faster D1 protein degradation at high light. However, after photoinhibition, greater accumulation of D1 during the night enabled them faster recovery. So, the most photosynthetic parameters, as the maximum quantum yield for primary photochemistry, electron transport and overall photosynthetic efficiency in mature leaves successfully restored to their initial values at 1a.m. Reduced connectivity of light harvesting complexes II to its reaction centers (positive L-band) in young leaves increased dissipation of excess light causing less pressure to D1 and its slower degradation. Decreased electron transport in young leaves, due to reduced transfer beyond primary acceptor Q A - most probably additionally induced degradation of Rubisco large subunit what consequently led to the stronger decrease of overall photosynthetic efficiency in young leaves at noon. Copyright © 2016 Elsevier GmbH. All rights reserved.

A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study.

PubMed

Li, Guang; Luo, Shouhua; Yan, Yuling; Gu, Ning

2015-01-01

The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons. In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image. By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator. The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study

PubMed Central

2015-01-01

Background The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons. Methods In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image. Results By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator. Conclusions The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion. PMID:25602532

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.

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.

Radiolysis of paracetamol in dilute aqueous solution

NASA Astrophysics Data System (ADS)

Szabó, László; Tóth, Tünde; Homlok, Renáta; Takács, Erzsébet; Wojnárovits, László

2012-09-01

Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2-3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily.

High-temperature superconductor antenna investigations

NASA Technical Reports Server (NTRS)

Karasack, Vincent G.

1990-01-01

The use of superconductors to increase antenna radiation efficiency and gain is examined. Although the gain of all normal-metal antennas can be increased through the use of superconductors, some structures have greater potential for practical improvement than others. Some structures suffer a great degradation in bandwidth when replaced with superconductors, while for others the improvement in efficiency is trivial due to the minimal contribution of the conductor loss mechanism to the total losses, or the already high efficiency of the structure. The following antennas and related structures are discussed: electrically small antennas, impedance matching of antennas, microstrip antennas, microwave and millimeter-wave antenna arrays, and superdirective arrays. The greatest potential practical improvements occur for large microwave and millimeter-wave arrays and the impedance matching of antennas.

Rift Valley fever virus NSs inhibits host transcription independently of the degradation of dsRNA-dependent Protein Kinase PKR

PubMed Central

Kalveram, Birte; Lihoradova, Olga; Indran, Sabarish V.; Lokugamage, Nandadeva; Head, Jennifer A.; Ikegami, Tetsuro

2012-01-01

Rift Valley fever virus (RVFV) encodes one major virulence factor, the NSs protein. NSs suppresses host general transcription, including interferon (IFN)-β mRNA synthesis, and promotes degradation of the dsRNA-dependent protein kinase (PKR). We generated a novel RVFV mutant (rMP12-NSsR173A) specifically lacking the function to promote PKR degradation. rMP12-NSsR173A infection induces early phosphorylation of eIF2α through PKR activation, while retaining the function to inhibit host general transcription including IFN-β gene inhibition. MP-12 NSs but not R173A NSs binds to wt PKR. R173A NSs formed filamentous structure in nucleus in a mosaic pattern, which was distinct from MP-12 NSs filament pattern. Due to early phosphorylation of eIF2α, rMP12-NSsR173A could not efficiently accumulate viral proteins. Our results suggest that NSs-mediated host general transcription suppression occurs independently of PKR degradation, while the PKR degradation is important to inhibit the phosphorylation of eIF2α in infected cells undergoing host general transcription suppression. PMID:23063407

Rift Valley fever virus NSs inhibits host transcription independently of the degradation of dsRNA-dependent protein kinase PKR.

PubMed

Kalveram, Birte; Lihoradova, Olga; Indran, Sabarish V; Lokugamage, Nandadeva; Head, Jennifer A; Ikegami, Tetsuro

2013-01-20

Rift Valley fever virus (RVFV) encodes one major virulence factor, the NSs protein. NSs suppresses host general transcription, including interferon (IFN)-β mRNA synthesis, and promotes degradation of the dsRNA-dependent protein kinase (PKR). We generated a novel RVFV mutant (rMP12-NSsR173A) specifically lacking the function to promote PKR degradation. rMP12-NSsR173A infection induces early phosphorylation of eIF2α through PKR activation, while retaining the function to inhibit host general transcription including IFN-β gene inhibition. MP-12 NSs but not R173A NSs binds to wt PKR. R173A NSs formed filamentous structure in nucleus in a mosaic pattern, which was distinct from MP-12 NSs filament pattern. Due to early phosphorylation of eIF2α, rMP12-NSsR173A could not efficiently accumulate viral proteins. Our results suggest that NSs-mediated host general transcription suppression occurs independently of PKR degradation, while the PKR degradation is important to inhibit the phosphorylation of eIF2α in infected cells undergoing host general transcription suppression. Copyright © 2012 Elsevier Inc. All rights reserved.

Degradation and metabolism of synthetic plastics and associated products by Pseudomonas sp.: capabilities and challenges.

PubMed

Wilkes, R A; Aristilde, L

2017-09-01

Synthetic plastics, which are widely present in materials of everyday use, are ubiquitous and slowly-degrading polymers in environmental wastes. Of special interest are the capabilities of microorganisms to accelerate their degradation. Members of the metabolically diverse genus Pseudomonas are of particular interest due to their capabilities to degrade and metabolize synthetic plastics. Pseudomonas species isolated from environmental matrices have been identified to degrade polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polyethylene terephthalate, polyethylene succinate, polyethylene glycol and polyvinyl alcohol at varying degrees of efficiency. Here, we present a review of the current knowledge on the factors that control the ability of Pseudomonas sp. to process these different plastic polymers and their by-products. These factors include cell surface attachment within biofilms, catalytic enzymes involved in oxidation or hydrolysis of the plastic polymer, metabolic pathways responsible for uptake and assimilation of plastic fragments and chemical factors that are advantageous or inhibitory to the biodegradation process. We also highlight future research directions required in order to harness fully the capabilities of Pseudomonas sp. in bioremediation strategies towards eliminating plastic wastes. © 2017 The Society for Applied Microbiology.

Enhanced photocatalytic activity of nanocellulose supported zinc oxide composite for RhB dye as well as ciprofloxacin drug under sunlight/visible light

NASA Astrophysics Data System (ADS)

Tavker, Neha; Sharma, Manu

2018-05-01

Zinc oxide nanoparticles were synthesised from zinc acetate di-hydrate via co-precipitation method. Nanocellulose was isolated from agrowaste using chemo-mechanical treatments and characterized. Nanocellulose supported zinc oxide composites were prepared through in-situ method by adding different amounts of nanocellulose. The photocatalytic efficiency of pure Zno and nanocellulose supported ZnO was calculated using RhB dye under visible light and sun light. The composites which had nanocellulose in greater ratio showed higher degradation efficiency in sunlight rather than visible light for both; dye and drug. All the composites showed high rate of photodegradation compared to bare ZnO and bare nanocellulose. The enhancement in photocatalytic activity was observed maximum where the amount of cellulose was maximum. The maximum observed rate was 0.025 min-1 using Ciprofloxacin drug due to the increase in lifetime of Z4 sample delaying the electron and hole pair recombination. The degrading efficiency of nanocellulose supported zinc oxide (NC/ZnO) composite for RhB was found to be 35% in visible, 76% in sunlight and 75% for ciprofloxacin under sunlight.

Preliminary Feasibility Study of Benzo(a)Pyrene Oxidative Degradation by Fenton Treatment

PubMed Central

Homem, Vera; Dias, Zélia; Santos, Lúcia; Alves, Arminda

2009-01-01

Polycyclic aromatic hydrocarbons (PAHs) are considered priority compounds due to their toxic and carcinogenic nature. The concern about water contamination and the consequent human exposure has encouraged the development of new methods for PAHs removal. The purpose of this work was to study the feasibility of a degradation process of benzo(a)pyrene (BaP) in aqueous matrices by oxidation with Fenton reagent. A laboratory unit was designed to optimize the factors which may influence the process: pH (3.5 to 6.0), temperature (30 to 70°C), H2O2 (20 to 150 mg L−1), Fe2+ concentration (2.75 to 5.50 mg L−1), and the initial concentration of the pollutant (10 to 100 μg L−1). The pH did not influence significantly the results in the range studied. An increase in temperature from 30 to 70°C improved the removal efficiency from 90% to 100%. The same effect was observed for ferrous ion concentrations from 2.75 to 5.50 mg L−1 (increase from 78% to 100% removal). The H2O2 concentration played a double role during the process: from 20 to 50 mg L−1 an increase in the removal efficiency was achieved, but for higher concentrations (>50 mg L−1) the degradation is lower. This study proved that the degradation of benzo(a)pyrene by Fenton's reagent is a viable process. PMID:19936125

Isolation and lipid degradation profile of Raoultella planticola strain 232-2 capable of efficiently catabolizing edible oils under acidic conditions.

PubMed

Sugimori, Daisuke; Watanabe, Mika; Utsue, Tomohiro

2013-01-01

The lipids (fats and oils) degradation capabilities of soil microorganisms were investigated for possible application in treatment of lipids-contaminated wastewater. We isolated a strain of the bacterium Raoultella planticola strain 232-2 that is capable of efficiently catabolizing lipids under acidic conditions such as in grease traps in restaurants and food processing plants. The strain 232-2 efficiently catabolized a mixture (mixed lipids) of commercial vegetable oil, lard, and beef tallow (1:1:1, w/w/w) at 20-35 °C, pH 3-9, and 1,000-5,000 ppm lipid content. Highly effective degradation rate was observed at 35 °C and pH 4.0, and the 24-h degradation rate was 62.5 ± 10.5 % for 3,000 ppm mixed lipids. The 24-h degradation rate for 3,000 ppm commercial vegetable oil, lard, beef tallow, mixed lipids, and oleic acid was 71.8 %, 58.7 %, 56.1 %, 55.3 ± 8.5 %, and 91.9 % at pH 4 and 30 °C, respectively. R. planticola NBRC14939 (type strain) was also able to efficiently catabolize the lipids after repeated subculturing. The composition of the culture medium strongly influenced the degradation efficiency, with yeast extract supporting more complete dissimilation than BactoPeptone or beef extract. The acid tolerance of strain 232-2 is proposed to result from neutralization of the culture medium by urease-mediated decomposition of urea to NH(3). The rate of lipids degradation increased with the rates of neutralization and cell growth. Efficient lipids degradation using strain 232-2 has been achieved in the batch treatment of a restaurant wastewater.

Co-Metabolic Degradation of β-Cypermethrin and 3-Phenoxybenzoic Acid by Co-Culture of Bacillus licheniformis B-1 and Aspergillus oryzae M-4.

PubMed

Zhao, Jiayuan; Chi, Yuanlong; Xu, Yingchao; Jia, Dongying; Yao, Kai

2016-01-01

The degradation efficiency of organic contaminants and their associated metabolites by co-culture of microbes is mainly limited by toxic intermediates from co-metabolic degradation. In this study, we investigated the degradation of β-cypermethrin (β-CY) and 3-phenoxybenzoic acid (3-PBA) by co-culture of Bacillus licheniformis B-1 and Aspergillus oryzae M-4, as well as the influences of β-CY and 3-PBA metabolites on their degradation and the growth of strains B-1 and M-4. Our results indicated that 100 mg/L β-CY was degraded by 78.85%, and 3-PBA concentration was 0.05 mg/L after 72 h. Compared with using only strain B-1, the half-life (t1/2) of β-CY by using the two strains together was shortened from 84.53 h to 38.54 h, and the yield coefficient of 3-PBA was decreased from 0.846 to 0.001. At 100 mg/L of 3-PBA and gallic acid, β-CY and 3-PBA degradation were only 17.68% and 40.45%, respectively. As the toxic intermediate derived from co-metabolic degradation of β-CY by strain B-1, 3-PBA was efficiently degraded by strain M-4, and gallic acid, as the toxic intermediate from co-metabolic degradation of 3-PBA by strain M-4, was efficiently degraded by strain B-1. These results provided a promising approach for efficient biodegradation of β-CY and 3-PBA.

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.

Reliable LC-MS quantitative glycomics using iGlycoMab stable isotope labeled glycans as internal standards.

PubMed

Zhou, Shiyue; Tello, Nadia; Harvey, Alex; Boyes, Barry; Orlando, Ron; Mechref, Yehia

2016-06-01

Glycans have numerous functions in various biological processes and participate in the progress of diseases. Reliable quantitative glycomic profiling techniques could contribute to the understanding of the biological functions of glycans, and lead to the discovery of potential glycan biomarkers for diseases. Although LC-MS is a powerful analytical tool for quantitative glycomics, the variation of ionization efficiency and MS intensity bias are influencing quantitation reliability. Internal standards can be utilized for glycomic quantitation by MS-based methods to reduce variability. In this study, we used stable isotope labeled IgG2b monoclonal antibody, iGlycoMab, as an internal standard to reduce potential for errors and to reduce variabililty due to sample digestion, derivatization, and fluctuation of nanoESI efficiency in the LC-MS analysis of permethylated N-glycans released from model glycoproteins, human blood serum, and breast cancer cell line. We observed an unanticipated degradation of isotope labeled glycans, tracked a source of such degradation, and optimized a sample preparation protocol to minimize degradation of the internal standard glycans. All results indicated the effectiveness of using iGlycoMab to minimize errors originating from sample handling and instruments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Online estimation of internal stack temperatures in solid oxide fuel cell power generating units

NASA Astrophysics Data System (ADS)

Dolenc, B.; Vrečko, D.; Juričić, Ɖ.; Pohjoranta, A.; Pianese, C.

2016-12-01

Thermal stress is one of the main factors affecting the degradation rate of solid oxide fuel cell (SOFC) stacks. In order to mitigate the possibility of fatal thermal stress, stack temperatures and the corresponding thermal gradients need to be continuously controlled during operation. Due to the fact that in future commercial applications the use of temperature sensors embedded within the stack is impractical, the use of estimators appears to be a viable option. In this paper we present an efficient and consistent approach to data-driven design of the estimator for maximum and minimum stack temperatures intended (i) to be of high precision, (ii) to be simple to implement on conventional platforms like programmable logic controllers, and (iii) to maintain reliability in spite of degradation processes. By careful application of subspace identification, supported by physical arguments, we derive a simple estimator structure capable of producing estimates with 3% error irrespective of the evolving stack degradation. The degradation drift is handled without any explicit modelling. The approach is experimentally validated on a 10 kW SOFC system.

Design of Aminopolymer Structure to Enhance Performance and Stability of CO2 Sorbents: Poly(propylenimine) vs Poly(ethylenimine).

PubMed

Pang, Simon H; Lee, Li-Chen; Sakwa-Novak, Miles A; Lively, Ryan P; Jones, Christopher W

2017-03-15

Studies on aminopolymer/oxide composite materials for direct CO 2 capture from air have often focused on the prototypical poly(ethylenimine) (PEI) as the aminopolymer. However, it is known that PEI will oxidatively degrade at elevated temperatures. This degradation has been ascribed to the presence of secondary amines, which, when oxidized, lose their CO 2 capture capacity. Here, we demonstrate the use of small molecule poly(propylenimine) (PPI) in linear and dendritic architectures supported in silica as adsorbent materials for direct CO 2 capture from air. Regardless of amine loading or aminopolymer architecture, the PPI-based sorbents are found to be more efficient for CO 2 capture than PEI-based sorbents. Moreover, PPI is found to be more resistant to oxidative degradation than PEI, even while containing secondary amines, as supported by FTIR, NMR, and ESI-MS studies. These results suggest that PPI-based CO 2 sorbents may allow for longer sorbent working lifetimes due to an increased tolerance to sorbent regeneration conditions and suggest that the presence of secondary amines may not mean that all aminopolymers will oxidatively degrade.

Impact of liposomal encapsulation on degradation of anthocyanins of black carrot extract by adding ascorbic acid.

PubMed

Guldiken, Burcu; Gibis, Monika; Boyacioglu, Dilek; Capanoglu, Esra; Weiss, Jochen

2017-03-22

Black carrot anthocyanins are known to be relatively stable because they contain acylated anthocyanins. The degradation of vitamin C (l-ascorbic acid) on anthocyanins is a known fact in beverage systems. In this study, the effects of various liposomal systems, including black carrot extract (0.1%, 0.2%, 0.4% w/w) and lecithin (1%, 2%, 4% w/w), on the color and degradation of anthocyanin in different ascorbic acid (0.01%, 0.025%, 0.05%, 0.1% w/w) concentrations were examined via UV/VIS spectroscopy and visual control of the color. The physical characteristics of the liposomal systems resulted in particle diameters of 41-46 nm and zeta-potentials of (-23)-(-20) mV. The encapsulation efficiencies of the liposomal systems increased up to 50% with increasing lecithin concentrations. The encapsulation of black carrot extract in liposomes enhanced the color and stability of the anthocyanins during storage. This study showed that the degradation of anthocyanins due to ascorbic acid can be reduced by liposomes in aqueous solutions.

The Correction of Fiber Throughput Variation due to Focal Ratio Degradation

NASA Astrophysics Data System (ADS)

Chen, Jianjun; Bai, Zhongrui; Li, Guangwei; Zhang, Haotong

2014-01-01

The focal ratio degradation (FRD) of optical fibers is a major source causing light loss to astronomical multi-fibre instruments like LAMOST (Oliveira, A. C, et al. 2005). The effects of stress and twist during mounting and rotation of the fibers could change the FRD for individual fibers (Clayton 1989), which means that the transmission efficiency of each individual fiber will vary. We investigate such throughput variation among LAMOST fibers and its relevance to the intensity of sky emission lines (Garstang 1989) over the full wavelength coverage. On the basis of the work, we present an approach to correct the varied fiber throughput by measuring the strength of the sky emission lines as the secondary throughput correction.

Efficient photocatalytic degradation of rhodamine 6G with a quantum dot-metal organic framework nanocomposite.

PubMed

Kaur, Rajnish; Vellingiri, Kowsalya; Kim, Ki-Hyun; Paul, A K; Deep, Akash

2016-07-01

The hybrid structures of metal organic frameworks (MOFs) and nanoparticles may offer the realization of effective photocatalytic materials due to combined benefits of the porous and molecular sieving properties of MOF matrix and the functional characteristics of encapsulated nanoparticles. In this study, cadmium telluride (CdTe) quantum dots (QD) are conjugated with a europium-MOF for the synthesis of a novel nanocomposite material with photocatalytic properties. Successful synthesis of a QD/Eu-MOF nanocomposite was characterized with various spectroscopic and microscopic techniques. This QD/Eu-MOF is found to be an effective catalyst to complete the degradation of Rhodamine 6G dye within 50 min. Copyright © 2016 Elsevier Ltd. All rights reserved.

Role of Autophagy in Glycogen Breakdown and Its Relevance to Chloroquine Myopathy

PubMed Central

Zirin, Jonathan; Nieuwenhuis, Joppe; Perrimon, Norbert

2013-01-01

Several myopathies are associated with defects in autophagic and lysosomal degradation of glycogen, but it remains unclear how glycogen is targeted to the lysosome and what significance this process has for muscle cells. We have established a Drosophila melanogaster model to study glycogen autophagy in skeletal muscles, using chloroquine (CQ) to simulate a vacuolar myopathy that is completely dependent on the core autophagy genes. We show that autophagy is required for the most efficient degradation of glycogen in response to starvation. Furthermore, we show that CQ-induced myopathy can be improved by reduction of either autophagy or glycogen synthesis, the latter possibly due to a direct role of Glycogen Synthase in regulating autophagy through its interaction with Atg8. PMID:24265594

Assessment of the degradation efficiency of full-scale biogas plants: A comparative study of degradation indicators.

PubMed

Li, Chao; Nges, Ivo Achu; Lu, Wenjing; Wang, Haoyu

2017-11-01

Increasing popularity and applications of the anaerobic digestion (AD) process has necessitated the development and identification of tools for obtaining reliable indicators of organic matter degradation rate and hence evaluate the process efficiency especially in full-scale, commercial biogas plants. In this study, four biogas plants (A1, A2, B and C) based on different feedstock, process configuration, scale and operational performance were selected and investigated. Results showed that the biochemical methane potential (BMP) based degradation rate could be use in incisively gauging process efficiency in lieu of the traditional degradation rate indicators. The BMP degradation rates ranged from 70 to 90% wherein plants A2 and C showed the highest throughput. This study, therefore, corroborates the feasibility of using the BMP degradation rate as a practical tool for evaluating process performance in full-scale biogas processes and spots light on the microbial diversity in full-scale biogas processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

High Beginning-of-Life Efficiency p/n InP Solar Cells

NASA Technical Reports Server (NTRS)

Hoffman, Richard W., Jr.; Fatemi, Navid S.; Weizer, Victor G.; Jenkins, Phillip P.; Ringel, Steven A.; Scheiman, David A.; Wilt, David M.; Brinker, David J.

2004-01-01

We have achieved a new record efficiency of 17.6%, (AM0) for a p/n InP homo-epitaxy solar cell. In addition, we have eliminated a previously observed photo-degradation of cell performance, which was due to losses in J(sub sc). Cells soaked in AM0 spectrum at one-sun intensity for an hour showed no significant change in cell performance. We have discovered carrier passivation effects when using Zn as the p-type dopant in the OMVPE growth of InP and have found a method to avoid the unexpected effects which result from typical operation of OMVPE cell growth.

Turbine Engine Clearance Control Systems: Current Practices and Future Directions

NASA Astrophysics Data System (ADS)

Lattime, Scott B.; Steinetz, Bruce M.

2002-09-01

Improved blade tip sealing in the high pressure compressor (HPC) and high pressure turbine (HPT) can provide dramatic reductions in specific fuel consumption (SFC), time-on-wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed 1M. Engine removal from service is primarily due to spent exhaust gas temperature (EGT) margin caused mainly by the deterioration of HPT components. Increased blade tip clearance is a major factor in hot section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero gas turbine engine HPT performance degradation and the mechanisms that promote these losses are discussed. Benefits to the HPT due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next generation engine clearance control systems.

Turbine Engine Clearance Control Systems: Current Practices and Future Directions

NASA Technical Reports Server (NTRS)

Lattime, Scott B.; Steinetz, Bruce M.

2002-01-01

Improved blade tip sealing in the high pressure compressor (HPC) and high pressure turbine (HPT) can provide dramatic reductions in specific fuel consumption (SFC), time-on-wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed $1M. Engine removal from service is primarily due to spent exhaust gas temperature (EGT) margin caused mainly by the deterioration of HPT components. Increased blade tip clearance is a major factor in hot section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero gas turbine engine HPT performance degradation and the mechanisms that promote these losses are discussed. Benefits to the HPT due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next generation engine clearance control systems.

Operating aerobic wastewater treatment at very short sludge ages enables treatment and energy recovery through anaerobic sludge digestion.

PubMed

Ge, Huoqing; Batstone, Damien J; Keller, Jurg

2013-11-01

Conventional abattoir wastewater treatment processes for carbon and nutrient removal are typically designed and operated with a long sludge retention time (SRT) of 10-20 days, with a relatively high energy demand and physical footprint. The process also generates a considerable amount of waste activated sludge that is not easily degradable due to the long SRT. In this study, an innovative high-rate sequencing batch reactor (SBR) based wastewater treatment process with short SRT and hydraulic retention time (HRT) is developed and characterised. The high-rate SBR process was shown to be most effective with SRT of 2-3 days and HRT of 0.5-1 day, achieving >80% reduction in chemical oxygen demand (COD) and phosphorus and approximately 55% nitrogen removal. A majority of carbon removal (70-80%) was achieved by biomass assimilation and/or accumulation, rather than oxidation. Anaerobic degradability of the sludge generated in the high-rate SBR process was strongly linked to SRT, with measured degradability extent being 85% (2 days SRT), 73% (3 days), and 63% (4 days), but it was not influenced by digestion temperature. However, the rate of degradation for 3 and 4 days SRT sludge was increased by 45% at thermophilic conditions compared to mesophilic conditions. Overall, the treatment process provides a very compact and energy efficient treatment option for highly degradable wastewaters such as meat and food processing, with a substantial space reduction by using smaller reactors and a considerable net energy output through the reduced aerobic oxidation and concurrent increased methane production potential through the efficient sludge digestion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of temperature and irradiation influence on the physicochemical properties of Aspirin

NASA Astrophysics Data System (ADS)

Al-Maydama, Hussein M.; Abduljabbar, Adlia A.; Al-Maqtari, Maher A.; Naji, Khalid M.

2018-04-01

Pure Aspirin samples were treated with a wide spectrum of light (γ-ray, UV- lamp and sunlight) and 40 °C temperature at various time of exposure. The changes in the thermal degradation parameters, crystalline structure, morphology and purity due to radiation and temperature treatments of Aspirin were pursued by comparing their TGA, XRD, SEM and HPLC results. The non-isothermal thermogravimetric analysis curves (TG, DTG and DSC) at 10 °C min-1 heating rate, under nitrogen flow and overheating range of 25-650 °C showed two degradation steps for the treated and untreated Aspirin samples. Accordingly, their thermal behavior and thermal stability were determined. Aspirin samples treated with 40 °C and UV-12 h were proven to be of the lowest thermal stability as their TDTG values (166.7 and 168.8 °C) were lower than that of the untreated sample (TDTG = 181 °C). The degradation kinetics parameters (i.e. activation energy, pre-exponential factor and order of reaction), life time prediction and thermodynamic parameters (ΔG*, ΔH* and ΔS*) were worked out using the Coats-Redfern (CR) expression and standard equations. The lowest activation energy (104.3 kJ mol-1) associated with the highest degradation rate was observed for the UV-12 h treated Aspirin sample. Crystallinity percentage was estimated from XRD and DSC, whereas, morphology and purity changes due to treatments were detected by scanning electron microscopy (SEM) and HPLC. The significant change in crystallinity from the XRD results of the treated Aspirin samples occurred in the (32.2%-58.7%) range. The photocatalytic degradation of Aspirin samples before and after treatments was carried out using TiO2/sunlight system. The photocatalytic degradation of all samples followed pseudo first order kinetics and the shelf life, rate of reaction and efficiency of degradation were determined and discussed. The highest degradation percentage (∼99%) and the associated lowest shelf life (4.3-5.8 min) were observed in the photocatalytic degradation of the 40 °C, UV-12 h, γ-ray-aqueous and sunlight treated samples.

Degradation properties of protein and carbohydrate during sludge anaerobic digestion.

PubMed

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

2015-09-01

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

Nano-zinc oxide incorporated graphene oxide/nanocellulose composite for the adsorption and photo catalytic degradation of ciprofloxacin hydrochloride from aqueous solutions.

PubMed

Anirudhan, T S; Deepa, J R

2017-03-15

Purpose of this study is to report the synthetic procedure of a novel photo catalyst, nano zinc oxide incorporated graphene oxide/nanocellulose (ZnO-GO/NC) for the effective adsorption and subsequent photo degradation of ciprofloxacin (CF), an antibiotic widely used in the poultry. Self cleaning property in cellulose was achieved by introducing a nano zinc oxide incorporated graphene oxide into nanocellulose (NC) matrix. By incorporating nano zinc oxide (ZnO) in graphene oxide (GO), band gap could be tuned to 2.4eV and after the composite formation with NC, the band gap was enhanced to 2.8eV which is in the visible region. Thus the degradation of the CF was achieved under the visible light. Photo degradation was due to electron hole interaction. The step wise modification in the synthesis ZnO-GO/NC was characterized using FT-IR, XRD, SEM, EDS, AFM, DRS-UV and BET N 2 adsorption isotherm techniques. The values of surface area, pore volume and pore radius were found to be 12.68m 2 /g, 0.026mL/g and 12.5nm, respectively. Efficiency in the adsorption process of CF onto ZnO-GO/NC was verified by batch adsorption technique. The optimum pH was found to be 5.5 and dose of the ZnO-GO/NC was optimized as 2.0g/L. Equilibrium was attained at 120min and the adsorption of drug followed second-order kinetics. Sips isotherm was the best fitted model and could explain the nature of interaction of CF with ZnO-GO/NC. The studies revealed that the degradation followed first-order kinetics and the optimum pH for the degradation process was found to be 6.0 and achieved a maximum degradation efficiency of 98.0%. The reusability of ZnO-GO/NC after five consecutive cycles indicated it to be a potential candidate for the removal and degradation of CF from aquatic environment. Copyright © 2016 Elsevier Inc. All rights reserved.

Degradation of atenolol via heterogeneous activation of persulfate by using BiOCl@Fe3O4 catalyst under simulated solar light irradiation.

PubMed

Shi, Yahong; Chen, Hongche; Wu, Yanlin; Dong, Wenbo

2018-01-01

Efficient oxidative degradation of pharmaceutical pollutants in aquatic environments is of great importance. This study used magnetic BiOCl@Fe 3 O 4 catalyst to activate persulfate (PS) under simulated solar light irradiation. This degradation system was evaluated using atenolol (ATL) as target pollutant. Four reactive species were identified in the sunlight/BiOCl@Fe 3 O 4 /PS system. The decreasing order of the contribution of each reactive species on ATL degradation was as follows: h +  ≈ HO ·  > O 2 ·-  > SO 4 ·- . pH significantly influenced ATL degradation, and an acidic condition favored the reaction. High degradation efficiencies were obtained at pH 2.3-5.5. ATL degradation rate increased with increased catalyst and PS contents. Moreover, ATL mineralization was higher in the sunlight/BiOCl@Fe 3 O 4 /PS system than in the sunlight/BiOCl@Fe 3 O 4 or sunlight/PS system. Nine possible intermediate products were identified through LC-MS analysis, and a degradation pathway for ATL was proposed. The BiOCl@Fe 3 O 4 nanomagnetic composite catalyst was synthesized in this work. This catalyst was easily separated and recovered from a treated solution by using a magnet, and it demonstrated a high catalytic activity. Increased amount of the BiOCl@Fe 3 O 4 catalyst obviously accelerated the efficiency of ATL degradation, and the reusability of the catalyst allowed the addition of a large dosage of BiOCl@Fe 3 O 4 to improve the degradation efficiency.

Evaluation of Fuel Cell Operation and Degradation

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

Williams, Mark; Gemmen, Randall; Richards, George

The concepts of area specific resistance (ASR) and degradation are developed for different fuel cell operating modes. The concepts of exergetic efficiency and entropy production were applied to ASR and degradation. It is shown that exergetic efficiency is a time-dependent function useful describing the thermal efficiency of a fuel cell and the change in thermal efficiency of a degrading fuel cell. Entropy production was evaluated for the cases of constant voltage operation and constant current operation of the fuel cell for a fuel cell undergoing ohmic degradation. It was discovered that the Gaussian hypergeometric function describes the cumulative entropy andmore » electrical work produced by fuel cells operating at constant voltage. The Gaussian hypergeometric function is found in many applications in modern physics. This paper builds from and is an extension of several papers recently published by the authors in the Journal of The Electrochemical Society (ECS), ECS Transactions, Journal of Power Sources, and the Journal of Fuel Cell Science and Technology.« less

Physical mechanisms affecting hot carrier-induced degradation in gallium nitride HEMTs

NASA Astrophysics Data System (ADS)

Mukherjee, Shubhajit

Gallium Nitride or GaN-based high electron mobility transistors (HEMTs) is currently the most promising device technology in several key military and civilian applications due to excellent high-power as well as high-frequency performance. Even though the performance figures are outstanding, GaN-based HEMTs are not as mature as some competing technologies, which means that establishing the reliability of the technology is important to enable use in critical applications. The objective of this research is to understand the physical mechanisms affecting the reliability of GaN HEMTs at moderate drain biases (typically VDS < 30 V in the devices considered here). The degradation in device performance is believed to be due to the formation or modification of charged defects near the interface by hydrogen depassivation processes (due to electron-activated hydrogen removal) from energetic carriers. A rate-equation describing the defect generation process is formulated based on this assumption. A combination of ensemble Monte-Carlo (EMC) simulation statistics, ab-initio density functional theory (DFT) calculations, and accelerated stress experiments is used to relate the candidate defects to the overall degradation behavior (VT and gm). The focus of this work is on the 'semi-ON' mode of transistor operation in which the degradation is usually observed to be at its highest. This semi-ON state is reasonably close to the biasing region of class-AB high power amplifiers, which are popular because of the combination of high efficiency and low distortion that is associated with this configuration. The carrier-energy distributions are obtained using an EMC simulator that was developed specifically for III-V HFETs. The rate equation is used to model the degradation at different operating conditions as well as longer stress times from the result of one short duration stress test, by utilizing the carrier-energy distribution obtained from EMC simulations for one baseline condition. This work also attempts to identify the spatial location of these defects, and how this impacts the V T shift and gm degradation of the devices.

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

PubMed Central

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

2017-01-01

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

Effectiveness of a model constructed wetland system containing Cyperus papyrus in degrading diesel oil

NASA Astrophysics Data System (ADS)

Harbowo, Danni Gathot; Choesin, Devi Nandita

2014-03-01

Synergism between wetland systems and the provision of degrading bacterial inoculum is now being developed for the recovery of areas polluted waters of pollutants. In connection with the frequent cases of diesel oil pollution in the waters of Indonesia, we need a way of water treatment as an efficient. In this study conducted a series of tests to develop an construcred wetland design that can effectively degrade diesel oil. Tested five systems: blanko (A), substrated, without bacterial inoculums, and vegetation (B); with the addition of inoculum (C); subsrated and vegetated (D); substrated and vegetated with the addition of inoculum (E). Vegetation used in this study is Cyperus papyrus because it has the ability to absorb pollutants. Inoculum used was Pseudomonas aeruginosa and Enterobacter aerogenes which is a bacteria degrading organic compounds commonly found in water. To measure the effectiveness of the system, use several indicators to see the degradation of pollutants, namely changes in viscosity, surface tension of pollutants, and the emergence of compound degradation. Based on the results of the study can be determined that the substrated and vegetated system with Cyperus papyrus inoculum (E) was considered the most capable of degrading diesel oil due to the large changes in all parameters. In the system E, 40.6% increase viscosity, surface tension decreased 32.7%, the appearance of degradation compounds with relatively 3614.7 points, and increased to 227.8% TDS. In addition the environmental conditions in the system E also supports the growth of vegetation and degrading microbes.

Improved photocatalytic degradation rates of phenol achieved using novel porous ZrO2-doped TiO2 nanoparticulate powders.

PubMed

McManamon, Colm; Holmes, Justin D; Morris, Michael A

2011-10-15

This paper studies the photocatalytic degradation of phenol using zirconia-doped TiO(2) nanoparticles. ZrO(2) was chosen due to its promising results during preliminary studies. Particles smaller than 10nm were synthesised and doped with quantities of ZrO(2) ranging from 0.5 to 4% (molar metal content). Particles were calcined at different temperatures to alter the TiO(2) structure, from anatase to rutile, in order to provide an ideal ratio of the two phases. Powder X-ray diffraction (PXRD) analysis was used to examine the transformation between anatase and rutile. Degradation of phenol was carried out using a 40 W UV bulb at 365 nm and results were measured by UV-vis spectrometry. TEM images were obtained and show the particles exhibit a highly ordered structure. TiO(2) doped with 1% ZrO(2) (molar metal content) calcined at 700 °C proved to be the most efficient catalyst. This is due to an ideal anatase:rutlie ratio of 80:20, a large surface area and the existence of stable electron-hole pairs. ZrO(2) doping above the optimum loading acted as an electron-hole recombination centre for electron-hole pairs and reduced photocatalytic degradation. Synthesised photocatalysts compared favourably to the commercially available photocatalyst P25. The materials also demonstrated the ability to be recycled with similar results to those achieved on fresh material after 5 uses. Copyright © 2011 Elsevier B.V. All rights reserved.

A new sono-electrochemical method for enhanced detoxification of hydrophilic chloroorganic pollutants in water.

PubMed

Yasman, Yakov; Bulatov, Valery; Gridin, Vladimir V; Agur, Sabina; Galil, Noah; Armon, Robert; Schechter, Israel

2004-09-01

A new method for detoxification of hydrophilic chloroorganic pollutants in effluent water was developed, using a combination of ultrasound waves, electrochemistry and Fenton's reagent. The advantages of the method are exemplified using two target compounds: the common herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and its derivative 2,4-dichlorophenol (2,4-DCP). The high degradation power of this process is due to the large production of oxidizing hydroxyl radicals and high mass transfer due to sonication. Application of this sono-electrochemical Fenton process (SEF) treatment (at 20 kHz) with quite a small current density, accomplished almost 50% oxidation of 2,4-D solution (300 ppm, 1.2 mM) in just 60 s. Similar treatments ran for 600 s resulted in practically full degradation of the herbicide; sizable oxidation of 2,4-DCP also occurs. The main intermediate compounds produced in the SEF process were identified. Their kinetic profile was measured and a chemical reaction scheme was suggested. The efficiency of the SEF process is tentatively much higher than the reference degradation methods and the time required for full degradation is considerably shorter. The SEF process maintains high performance up to concentrations which are higher than reference methods. The optimum concentration of Fe2+ ions required for this process was found to be of about 2 mM, which is lower than that in reference techniques. These findings indicate that SEF process may be an effective method for detoxification of environmental water.

Microbial degradation of lignin: how a bulky recalcitrant polymer is efficiently recycled in nature and how we can take advantage of this

PubMed Central

Ruiz‐Dueñas, Francisco J.; Martínez, Ángel T.

2009-01-01

Summary Lignin is the second most abundant constituent of the cell wall of vascular plants, where it protects cellulose towards hydrolytic attack by saprophytic and pathogenic microbes. Its removal represents a key step for carbon recycling in land ecosystems, as well as a central issue for industrial utilization of plant biomass. The lignin polymer is highly recalcitrant towards chemical and biological degradation due to its molecular architecture, where different non‐phenolic phenylpropanoid units form a complex three‐dimensional network linked by a variety of ether and carbon–carbon bonds. Ligninolytic microbes have developed a unique strategy to handle lignin degradation based on unspecific one‐electron oxidation of the benzenic rings in the different lignin substructures by extracellular haemperoxidases acting synergistically with peroxide‐generating oxidases. These peroxidases posses two outstanding characteristics: (i) they have unusually high redox potential due to haem pocket architecture that enables oxidation of non‐phenolic aromatic rings, and (ii) they are able to generate a protein oxidizer by electron transfer to the haem cofactor forming a catalytic tryptophanyl‐free radical at the protein surface, where it can interact with the bulky lignin polymer. The structure–function information currently available is being used to build tailor‐made peroxidases and other oxidoreductases as industrial biocatalysts. PMID:21261911

Production by Tobacco Transplastomic Plants of Recombinant Fungal and Bacterial Cell-Wall Degrading Enzymes to Be Used for Cellulosic Biomass Saccharification.

PubMed

Longoni, Paolo; Leelavathi, Sadhu; Doria, Enrico; Reddy, Vanga Siva; Cella, Rino

2015-01-01

Biofuels from renewable plant biomass are gaining momentum due to climate change related to atmospheric CO2 increase. However, the production cost of enzymes required for cellulosic biomass saccharification is a major limiting step in this process. Low-cost production of large amounts of recombinant enzymes by transgenic plants was proposed as an alternative to the conventional microbial based fermentation. A number of studies have shown that chloroplast-based gene expression offers several advantages over nuclear transformation due to efficient transcription and translation systems and high copy number of the transgene. In this study, we expressed in tobacco chloroplasts microbial genes encoding five cellulases and a polygalacturonase. Leaf extracts containing the recombinant enzymes showed the ability to degrade various cell-wall components under different conditions, singly and in combinations. In addition, our group also tested a previously described thermostable xylanase in combination with a cellulase and a polygalacturonase to study the cumulative effect on the depolymerization of a complex plant substrate. Our results demonstrate the feasibility of using transplastomic tobacco leaf extracts to convert cell-wall polysaccharides into reducing sugars, fulfilling a major prerequisite of large scale availability of a variety of cell-wall degrading enzymes for biofuel industry.

Electrical efficiency and droop in MQW LEDs

NASA Astrophysics Data System (ADS)

Malyutenko, V. K.

2014-02-01

It is believed that low power conversion efficiency in commercial MQW LEDs occurs as a result of efficiency droop, current-induced dynamic degradation of the internal quantum efficiency, injection efficiency, and extraction efficiency. Broadly speaking, all these "quenching" mechanisms could be referred to as the optical losses. The vast advances of high-power InGaN and AlGaInP MQW LEDs have been achieved by addressing these losses. In contrast to these studies, in this paper we consider an alternative approach to make high-power LEDs more efficient. We identify current-induced electrical efficiency degradation (EED) as a strong limiting factor of power conversion efficiency. We found that EED is caused by current crowding followed by an increase in current-induced series resistance of a device. By decreasing the current spreading length, EED also causes the optical efficiency to degrade and stands for an important aspect of LED performance. This paper gives scientists the opportunity to look for different attributes of EED.

Rhizosphere of Avicennia marina (Forsk.) Vierh. as a landmark for polythene degrading bacteria.

PubMed

Shahnawaz, Mohd; Sangale, Manisha K; Ade, Avinash B

2016-07-01

Due to high durability, cheap cost, and ease of manufacture, 311 million tons of plastic-based products are manufactured around the globe per annum. The slow/least rate of plastic degradation leads to generation of million tons of plastic waste per annum, which is of great environmental concern. Of the total plastic waste generated, polythene shared about 64 %. Various methods are available in the literature to tackle with the plastic waste, and biodegradation is considered as the most accepted, eco-friendly, and cost-effective method of polythene waste disposal. In the present study, an attempt has been made to isolate, screen, and characterize the most efficient polythene degrading bacteria by using rhizosphere soil of Avicennia marina as a landmark. From 12 localities along the west coast of India, a total of 123 bacterial isolates were recorded. Maximum percent weight loss (% WL; 21.87 ± 6.37 %) was recorded with VASB14 at pH 3.5 after 2 months of shaking at room temperature. Maximum percent weight gain (13.87 ± 3.6 %) was reported with MANGB5 at pH 7. Maximum percent loss in tensile strength (% loss in TS; 87.50 ± 4.8 %) was documented with VASB1 at pH 9.5. The results based on the % loss in TS were only reproducible. Further, the level of degradation was confirmed by scanning electron microscopic (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. In SEM analysis, scions/crakes were found on the surface of the degraded polythene, and mass of bacterial cell was also recorded on the weight-gained polythene strips. Maximum reduction in carbonyl index (4.14 %) was recorded in untreated polythene strip with Lysinibacillus fusiformis strain VASB14/WL. Based on 16S ribosomal RNA (rRNA) gene sequence homology, the most efficient polythene degrading bacteria were identified as L. fusiformis strainVASB14/WL and Bacillus cereus strain VASB1/TS.

Conversion efficiency limits and bandgap designs for multi-junction solar cells with internal radiative efficiencies below unity.

PubMed

Zhu, Lin; Mochizuki, Toshimitsu; Yoshita, Masahiro; Chen, Shaoqiang; Kim, Changsu; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

2016-05-16

We calculated the conversion-efficiency limit ηsc and the optimized subcell bandgap energies of 1 to 5 junction solar cells without and with intermediate reflectors under 1-sun AM1.5G and 1000-sun AM1.5D irradiations, particularly including the impact of internal radiative efficiency (ηint) below unity for realistic subcell materials on the basis of an extended detailed-balance theory. We found that the conversion-efficiency limit ηsc significantly drops when the geometric mean ηint* of all subcell ηint in the stack reduces from 1 to 0.1, and that ηsc degrades linearly to logηint* for ηint* below 0.1. For ηint*<0.1 differences in ηsc due to additional intermediate reflectors became very small if all subcells are optically thick for sun light. We obtained characteristic optimized bandgap energies, which reflect both ηint* decrease and AM1.5 spectral gaps. These results provide realistic efficiency targets and design principles.

ZrO2/MoS2 heterojunction photocatalysts for efficient photocatalytic degradation of methyl orange

NASA Astrophysics Data System (ADS)

Prabhakar Vattikuti, Surya Veerendra; Byon, Chan; Reddy, Chandragiri Venkata

2016-10-01

We report a simple solution-chemistry approach for the synthesis of ZrO2/MoS2 hybrid photocatalysts, which contain MoS2 as a cocatalyst. The material is usually obtained by a wet chemical method using ZrO(NO3)2 or (NH4)6Mo7O24·4H2O and C8H6S as precursors. The structural features of obtained materials were characterized by X-ray diffraction (XRD), highresolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG-DTA), N2 adsorption-desorption, and photoluminescence (PL). The influence on the photocatalytic activity of the MoS2 cocatalyst concentration with ZrO2 nanoparticles was studied. The MZr-2 hybrid sample had the highest photocatalytic activity for the degradation of methyl orange (MO), which was 8.45 times higher than that of pristine ZrO2 ascribed to high specific surface area and absorbance efficiency. Recycling experiments revealed that the reusability of the MZr-2 hybrid was due to the low photocorrosive effect and good catalytic stability. PL spectra confirmed the electronic interaction between ZrO2 and MoS2. The photoinduced electrons could be easily transferred from CB of ZrO2 to the MoS2 cocatalyst, which facilitate effective charge separation and enhanced the photocatalytic degradation in the UV region. A photocatalytic mechanism is proposed. It is believed that the ZrO2/MoS2 hybrid structure has promise as a photocatalyst with low cost and high efficiency for photoreactions.

Abatement of trichloroethylene using DBD plasma

NASA Astrophysics Data System (ADS)

Vesali-Naseh, M.; Xu, S.; Xu, L.; Khodadadi, A.; Mortazavi, Y.; Ostrikov, K.

2014-08-01

Dielectric barrier discharge plasma was used to oxidize trichloroethylene (TCE) in 21% of O2 in carriers of N2 and He. The degradation products of TCE were analyzed using gas chromatography mass spectrometry. TCE was decomposed completely at optimum energy density of 260 and 300 J/l for He and N2, respectively and its conversion followed zero order reaction. The TCE removal efficiency is decreased in humid air due to interception of reactive intermediates by OH radicals.

Chitosan-carboxymethylcellulose based microcapsules formulation for controlled release of active ingredients from cosmeto textile

NASA Astrophysics Data System (ADS)

Roy, J. C.; Ferri, A.; Salaün, F.; Giraud, S.; Chen, G.; Jinping, G.

2017-10-01

Chitosan-based emulsions were prepared at pH from 4.0 to 6.0. The zeta potential and droplet size were monitored at different pH. Double emulsions (wateroil- water) were observed due to the stiff conformation of chitosan at pH 4.0. At pH 5.0, the emulsion droplets were the smallest (2.9 μm) of the experimental pH range. The emulsion droplets were well dispersed due to high surface charge of chitosan (for example, +50 mV at pH 5.5) in entire pH range. The emulsion was treated with carboxymethyl cellulose (CMC) for neutralizing the charged chitosan on the surface of emulsion droplets. Above 10×10-2 mg/ml of CMC, no change in zeta potential was observed indicating no more free chitosan existed after neutralization with CMC. The emulsion was then crosslinked with different amount of glutaraldehyde. Upon increasing the amount of glutaraldehyde, the amount of core content inside the microcapsule and encapsulation efficiency of shell materials decreased gradually. The Dynamic Scanning Calorimetry data confirmed no interaction between core and shell material in the microencapsulation process. The thermal degradation of the microcapsules was examined by thermogravimetric analysis and a gradual decrease in the degradation temperature upon increasing glutaraldehyde concentration was found. The tuning of CMC concentration can provide valuable information regarding stable emulsion and efficient microcapsule formulation via coacervation.

Continuous flow photochemistry.

PubMed

Gilmore, Kerry; Seeberger, Peter H

2014-06-01

Due to the narrow width of tubing/reactors used, photochemistry performed in micro- and mesoflow systems is significantly more efficient than when performed in batch due to the Beer-Lambert Law. Owing to the constant removal of product and facility of flow chemical scalability, the degree of degradation observed is generally decreased and the productivity of photochemical processes is increased. In this Personal Account, we describe a wide range of photochemical transformations we have examined using both visible and UV light, covering cyclizations, intermolecular couplings, radical polymerizations, as well as singlet oxygen oxygenations. Copyright © 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of process variables and kinetics on the degradation of 2,4-dichlorophenol using advanced reduction processes (ARP).

PubMed

Yu, Xingyue; Cabooter, Deirdre; Dewil, Raf

2018-05-24

This study aims at investigating the efficiency and kinetics of 2,4-DCP degradation via advanced reduction processes (ARP). Using UV light as activation method, the highest degradation efficiency of 2,4-DCP was obtained when using sulphite as a reducing agent. The highest degradation efficiency was observed under alkaline conditions (pH = 10.0), for high sulphite dosage and UV intensity, and low 2,4-DCP concentration. For all process conditions, first-order reaction rate kinetics were applicable. A quadratic polynomial equation fitted by a Box-Behnken Design was used as a statistical model and proved to be precise and reliable in describing the significance of the different process variables. The analysis of variance demonstrated that the experimental results were in good agreement with the predicted model (R 2  = 0.9343), and solution pH, sulphite dose and UV intensity were found to be key process variables in the sulphite/UV ARP. Consequently, the present study provides a promising approach for the efficient degradation of 2,4-DCP with fast degradation kinetics. Copyright © 2018 Elsevier B.V. All rights reserved.

Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization

PubMed Central

Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

2016-01-01

Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria. PMID:27176711

[Microwave assisted UV electrodeless discharge lamp photochemical degradation of 4-chlorophenol in aquatic solutions].

PubMed

Ai, Zhi-hui; Jiang, Jun-qing; Yang, Peng; Zhou, Tao; Lu, Xiao-hua

2004-07-01

A microwave assisted UV electrodeless discharge lamp system (MW/UV) was used for photo-degradation of 4CP simulated wastewater. In order to evaluate the degradation efficiency of 4CP, UV spectrophotometry and ion chromatography were used for determination of 4CP and Cl- respectively. The degradation rate in MW/UV system was higher than that in the UV system within 120min, which were 52.40% and 21.56% respectively. The degradation efficiency was improved by increasing pH value of the solution, aerating O2 gas, enhancing light intensity, or adding H2O2 oxidant. The degradation of 4CP under MW/UV accords with the first order kinetics equation.

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

PubMed

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

2017-11-01

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

Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature.

PubMed

Shao, Liming; Wang, Tianfeng; Li, Tianshui; Lü, Fan; He, Pinjing

2013-07-01

Aerobic and anaerobic digestion are popular methods for the treatment of waste activated sludge. However, the differences in degradation of sludge during aerobic and anaerobic digestion remain unclear. In this study, the sludge degradation during aerobic and anaerobic digestion was investigated at mesophilic temperature, focused on protein based on the degradation efficiency and degree of humification. The duration of aerobic and anaerobic digestion was about 90 days. The final degradation efficiency of volatile solid was 66.1 ± 1.6% and 66.4 ± 2.4% under aerobic and anaerobic conditions, respectively. The final degradation efficiency of protein was 67.5 ± 1.4% and 65.1 ± 2.6% under aerobic and anaerobic conditions, respectively. The degradation models of volatile solids were consistent with those of protein under both aerobic and anaerobic conditions. The solubility of protein under aerobic digestion was greater than that under anaerobic digestion. Moreover, the humification index of dissolved organic matter of aerobic digestion was greater than that during anaerobic digestion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Degradation of polyvinyl alcohol (PVA) by UV/chlorine oxidation: Radical roles, influencing factors, and degradation pathway.

PubMed

Ye, Bei; Li, Yue; Chen, Zhuo; Wu, Qian-Yuan; Wang, Wen-Long; Wang, Ting; Hu, Hong-Ying

2017-11-01

Polyvinyl alcohol (PVA) is widely used in industry but is difficult to degrade. In this study, the synergistic effect of UV irradiation and chlorination on degradation of PVA was investigated. UV irradiation or chlorination alone did not degrade PVA. By contrast, UV/chlorine oxidation showed good efficiency for PVA degradation via generation of active free radicals, such as OH and Cl. The relative importance of these two free radicals in the oxidation process was evaluated, and it was shown that OH contributed more to PVA degradation than Cl did. The degradation of PVA followed pseudo first order kinetics. The rate constant k increased linearly from 0 min -1 to 0.3 min -1 with increasing chlorine dosage in range of 0 mg/L to 20 mg/L. However, when the chlorine dosage was increased above 20 mg/L, scavenging effect of free radicals occurred, and the degradation efficiency of PVA did not increase much more. Acidic media increased the degradation efficiency of PVA by UV/chlorine oxidation more than basic or neutral media because of the higher ratio of [HOCl]/[OCl - ], higher free radical quantum yields, and the lower free radical quenching effect under acidic conditions. Results of Fourier Transform Infrared Spectroscopy showed that carbonyl groups in degradation products were formed during UV/chlorine oxidation, and a possible degradation pathway via alcohol to carbonyl was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of space-radiation damage and temperature on CCD noise for the Lyman FUSE mission

NASA Astrophysics Data System (ADS)

Murowinski, Richard G.; Gao, Linzhuang; Deen, Mohamed J.

1993-09-01

Charge coupled device (CCD) imaging arrays are becoming more frequently used in space vehicles and equipment, especially space-based astronomical telescopes. It is important to understand the effects of radiation on a CCD so that its performance degradation during mission lifetime can be predicted, and so that methods to prevent unacceptable performance degradation can be found. Much recent work by various groups has focused on the problems surrounding the loss of charge transfer efficiency and the increase in dark current and dark current spikes in CCDs. The use of a CCD as the fine error sensor in the Lyman Far Ultraviolet Spectroscopic Explorer (FUSE) is limited by its noise performance. In this work we attempt to understand some of the factors surrounding the noise degradation due to radiation in a space environment. Later, we demonstrate how low frequency noise can be used as a characterization tool for studying proton radiation damage in CCDs.

Effects of HPA-nonlinearity on a 4-DPSK/OFDM-signal for a digital sound broadcasting signal

NASA Astrophysics Data System (ADS)

Rapp, Christoph

1991-10-01

Orthogonal Frequency Division Multiplexing (OFDM) in conjunction with a 4 Differential Phase Shift Keying (DPSK) modulation format has been proposed for the future Digital Audio Broadcasting system (DAB), that should provide compact disk sound quality in portable, vehicular and fixed receivers. With properly chosen parameters, this system should be appropriate for both terrestrial and satellite transmission. The influence of the nonlinear distorsions introduced by the High Power Amplifier (HPA) of the transmitter is examined. In particular, the degradations in power efficiency due to intermodulation effects and backoff operating, as well as spectral degradations are investigated. It is shown for three different kinds of limiting amplifier models, that even with an output backoff in the region of 5 to 6 dB, the degradation of, for example a 512 carrier 4 DPSK/OFDM system relative to the linear case is below 1.7 dB (Pb = 0.0001), while the regenerated sidelobes of the transmitted spectrum are kept below -20 dB.

Kinetics of alkali-based photocathode degradation

DOE PAGES

Pavlenko, Vitaly; Liu, Fangze; Hoffbauer, Mark A.; ...

2016-11-02

Here, we report on a kinetic model that describes the degradation of the quantum efficiency (QE) of Cs 3Sb and negative electron affinity (NEA) GaAs photocathodes under UHV conditions. Additionally, the generally accepted irreversible chemical change of a photocathode’s surface due to reactions with residual gases, such as O 2, CO 2, and H 2O, the model incorporates an intermediate reversible physisorption step, similar to Langmuir adsorption. Moreover, this intermediate step is needed to satisfactorily describe the strongly non-exponential QE degradation curves for two distinctly different classes of photocathodes –surface-activated and “bulk,” indicating that in both systems the QE degradationmore » results from surface damage. The recovery of the QE upon improvement of vacuum conditions is also accurately predicted by this model with three parameters (rates of gas adsorption, desorption, and irreversible chemical reaction with the surface) comprising metrics to better characterize the lifetime of the cathodes, instead of time-pressure exposure expressed in Langmuir units.« less

Degradations to microprocessor-based systems due to environmental stressors

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

Messman, P. A.; Peilai, Z.; Goodenow, D. A.

Recent studies indicate that EMI/RFI is the most significant environmental Stressor with potential for leading to digital systems degradation and failure. With digital I and C and wireless technology becoming standard in many industrial environments, nuclear power plant operators of current and future plants will or already have implemented these technologies seeking to leverage the economic benefits of such technology. With digital I and C systems' higher susceptibility to EMI/RFI and the increased environmental noise introduced by wireless-based systems, this produces a dangerous combination that could lead to logic errors, equipment damage, and faults in digital I and C. Failuresmore » to these systems, especially to safety-critical systems, could lead to loss of system, which would pose a safety risk and decrease in operational efficiency. In order to better understand system degradations by these means and aid in regulation and guidance, we propose to experimentally study the susceptibility of digital I and C to wireless technology. (authors)« less

Diatomite Modified Immobilized Delftia sp. for the Bio-Abiotic Removal of Antibiotics Amoxicillin in the Aqueous System

NASA Astrophysics Data System (ADS)

Gao, Lijuan; Sun, Jing; Guan, Kai; Shen, Tingting; Wang, Xikui

2017-05-01

Diatomite modified sodium alginate (Si/SA) immobilized Delftia sp. A2(2011) (STT01) was applied to degrade amoxicillin. The immobilized pellets provided a direct and visual probe for the degradation process due to their intrinsic bright colour. The results demonstrated that 100% of amoxicillin and 68.5% of CODcr removal were achieved after 72 h, comparing with the cases of sodium alginate (SA) system (81.2%, 46.9%) and the free cells system (60.5%, 35.5%). The degradation kinetics was in good agreement with Michaelis-Menten equation. The maximum rate (Vm ) and Michaelis constant (Km ) were calculated as 9.09 mg L-1 h-1 and 228 mg L-1, respectively. The results further revealed that diatomite not only acted as immobilization support to improve the mechanical strength and lifetime of the pellets but also as absorbent to promote the treatment efficiency. Therefore, both enzymatic catalysis and chemisorption were responsible for the removal of amoxicillin.

Biological treatment of TMAH (tetra-methyl ammonium hydroxide) in a full-scale TFT-LCD wastewater treatment plant.

PubMed

Hu, Tai-Ho; Whang, Liang-Ming; Liu, Pao-Wen Grace; Hung, Yu-Ching; Chen, Hung-Wei; Lin, Li-Bin; Chen, Chia-Fu; Chen, Sheng-Kun; Hsu, Shu Fu; Shen, Wason; Fu, Ryan; Hsu, Romel

2012-06-01

This study evaluated biological treatment of TMAH in a full-scale methanogenic up-flow anaerobic sludge blanket (UASB) followed by an aerobic bioreactor. In general, the UASB was able to perform a satisfactory TMAH degradation efficiency, but the effluent COD of the aerobic bioreactor seemed to increase with an increased TMAH in the influent wastewater. The batch test results confirmed that the UASB sludge under methanogenic conditions would be favored over the aerobic ones for TMAH treatment due to its superb ability of handling high strength of TMAH-containing wastewaters. Based on batch experiments, inhibitory chemicals present in TFT-LCD wastewater like surfactants and sulfate should be avoided to secure a stable methanogenic TMAH degradation. Finally, molecular monitoring of Methanomethylovorans hollandica and Methanosarcina mazei in the full-scale plant, the dominant methanogens in the UASB responsible for TMAH degradation, may be beneficial for a stable TMAH treatment performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enhancement effects of chelating agents on the degradation of tetrachloroethene in Fe(III) catalyzed percarbonate system

PubMed Central

Miao, Zhouwei; Gu, Xiaogang; Lu, Shuguang; Brusseau, Mark L.; Zhang, Xiang; Fu, Xiaori; Danish, Muhammad; Qiu, Zhaofu; Sui, Qian

2015-01-01

The performance of Fe(III)-based catalyzed sodium percarbonate (SPC) for stimulating the oxidation of tetrachloroethene (PCE) for groundwater remediation applications was investigated. The chelating agents citric acid monohydrate (CIT), oxalic acid (OA), and Glutamic acid (Glu) significantly enhanced the degradation of PCE. Conversely, ethylenediaminetetraacetic acid (EDTA) had a negative impact on PCE degradation, which may due to its strong Fe chelation and HO• scavenging abilities. However, excessive SPC or chelating agent will retard PCE degradation. In addition, investigations using free radical probe compounds and radical scavengers revealed that PCE was primarily degraded by HO• radical oxidation in both the chelated and non-chelated systems, while O2•− also participated in the non-chelated system and the OA and Glu modified systems. According to the electron paramagnetic resonance (EPR) studies, the presence of HO• in the Fe(III)/SPC system was maintained much longer than that in the Fe(II)/SPC system. The results indicated that the addition of CIT, OA or Glu indeed enhanced the generation of HO• in the first 10 min and promoted degradation efficiency by increasing the amount of Fe(III) and maintaining the concentration of HO• radicals in solution. In conclusion, chelated Fe(III)-based catalyzed SPC oxidation is a promising method for the remediation of PCE-contaminated groundwater. PMID:26549979

Degradable Molybdenum Oxide Nanosheets with Rapid Clearance and Efficient Tumor Homing Capabilities as a Therapeutic Nanoplatform.

PubMed

Song, Guosheng; Hao, Jiali; Liang, Chao; Liu, Teng; Gao, Min; Cheng, Liang; Hu, Junqing; Liu, Zhuang

2016-02-05

Molybdenum oxide (MoOx) nanosheets with high near-infrared (NIR) absorbance and pH-dependent oxidative degradation properties were synthesized, functionalized with polyethylene glycol (PEG), and then used as a degradable photothermal agent and drug carrier. The nanosheets, which are relatively stable under acidic pH, could be degraded at physiological pH. Therefore, MoOx-PEG distributed in organs upon intravenous injection would be rapidly degraded and excreted without apparent in vivo toxicity. MoOx-PEG shows efficient accumulation in tumors, the acidic pH of which then leads to longer tumor retention of those nanosheets. Along with the capability of acting as a photothermal agent for effective tumor ablation, MoOx-PEG can load therapeutic molecules with high efficiencies. This concept of inorganic theranostic nanoagent should be relatively stable in tumors to allow imaging and treatment, while being readily degradable in normal organs to enable rapid excretion and avoid long-term retention/toxicity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal oxide composite enabled nanotextured Si photoanode for efficient solar driven water oxidation.

PubMed

Sun, Ke; Pang, Xiaolu; Shen, Shaohua; Qian, Xueqiang; Cheung, Justin S; Wang, Deli

2013-05-08

We present a study of a transition metal oxide composite modified n-Si photoanode for efficient and stable water oxidation. This sputter-coated composite functions as a protective coating to prevent Si from photodecomposition, a Schottky heterojunction, a hole conducting layer for efficient charge separation and transportation, and an electrocatalyst to reduce the reaction overpotential. The formation of mixed-valence oxides composed of Ni and Ru effectively modifies the optical, electrical, and catalytic properties of the coating material, as well as the interfaces with Si. The successful application of this oxide composite on nanotextured Si demonstrates improved conversion efficiency due to enhanced catalytic activity, minimized reflection, and increased surface reaction sites. Although the coated nanotextured Si shows a noticeable degradation from 500 cycles of operation, the oxide composite provides a simple method to enable unstable photoanode materials for solar fuel conversion.

Degradation of Acid Blue 25 in aqueous media using 1700kHz ultrasonic irradiation: ultrasound/Fe(II) and ultrasound/H(2)O(2) combinations.

PubMed

Ghodbane, Houria; Hamdaoui, Oualid

2009-06-01

In this work, the sonolytic degradation of an anthraquinonic dye, C.I. Acid Blue 25 (AB25), in aqueous phase using high frequency ultrasound waves (1700kHz) for an acoustic power of 14W was investigated. The sonochemical efficiency of the reactor was evaluated by potassium iodide dosimeter, Fricke reaction and hydrogen peroxide production yield. The three investigated methods clearly show the production of oxidizing species during sonication and well reflect the sonochemical effects of high frequency ultrasonic irradiation. The effect of operational conditions such as the initial AB25 concentration, solution temperature and pH on the degradation of AB25 was studied. Additionally, the influence of addition of salts on the degradation of dye was examined. The rate of AB25 degradation was dependent on initial dye concentration, pH and temperature. Addition of salts increased the degradation of dye. Experiments conducted using distilled and natural waters demonstrated that the degradation was more efficient in the natural water compared to distilled water. To increase the efficiency of AB25 degradation, experiments combining ultrasound with Fe(II) or H(2)O(2) were conducted. Fe(II) induced the dissociation of ultrasonically produced hydrogen peroxide, leading to additional OH radicals which enhance the degradation of dye. The combination of ultrasound with hydrogen peroxide looks to be a promising option to increase the generation of free radicals. The concentration of hydrogen peroxide plays a crucial role in deciding the extent of enhancement obtained for the combined process. The results of the present work indicate that ultrasound/H(2)O(2) and ultrasound/Fe(II) processes are efficient for the degradation of AB25 in aqueous solutions by high frequency ultrasonic irradiation.

Nanoscale zerovalent iron-mediated degradation of DDT in soil.

PubMed

Han, Yuling; Shi, Nan; Wang, Huifang; Pan, Xiong; Fang, Hua; Yu, Yunlong

2016-04-01

Nanoscale zerovalent iron (nZVI)-mediated degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) was investigated in a spiked soil under different conditions (iron sources, iron dosage, soil moisture, temperature, and soil types) and DDT-contaminated field. The degradation efficiency of p,p'-DDT by nZVI and nZVI coated with sodium oleate (SO-nZVI) was much higher than that by nZVI coated with polyimide (PI-nZVI). The rapid degradation of p,p'-DDT by nZVI only occurred in flooded soil. The degradation half-life of p,p'-DDT decreased significantly from 58.3 to 27.6 h with nZVI dosage from 0.5 to 2.0% and from 46.5 to 32.0 h with temperature from 15 to 35 °C. The degradation efficiency of p,p'-DDT by nZVI differed in Jinhua (JH), Jiaxing (JX), Xiaoshan (XS), Huajiachi (HJC), and Heilongjiang (HLJ) soils. A good correlation was found between the degradation half-life of p,p'-DDT and multiple soil properties. The probable nZVI-mediated degradation pathway of p,p'-DDT in soil was proposed as DDT → DDD/DDE → DDNS → DDOH based on the metabolites identified by GC-MS. The in situ degradation efficiency of residual DDTs in a contaminated field was profoundly enhanced by the addition of nZVI as compared to the control. It is concluded that nZVI might be an efficient agent for the remediation of DDT-contaminated soil under anaerobic environment.

Kinetic models and pathways of ronidazole degradation by chlorination, UV irradiation and UV/chlorine processes.

PubMed

Qin, Lang; Lin, Yi-Li; Xu, Bin; Hu, Chen-Yan; Tian, Fu-Xiang; Zhang, Tian-Yang; Zhu, Wen-Qian; Huang, He; Gao, Nai-Yun

2014-11-15

Degradation kinetics and pathways of ronidazole (RNZ) by chlorination (Cl2), UV irradiation and combined UV/chlorine processes were investigated in this paper. The degradation kinetics of RNZ chlorination followed a second-order behavior with the rate constants calculated as (2.13 ± 0.15) × 10(2) M(-2) s(-1), (0.82 ± 0.52) × 10(-2) M(-1) s(-1) and (2.06 ± 0.09) × 10(-1) M(-1) s(-1) for the acid-catalyzed reaction, as well as the reactions of RNZ with HOCl and OCl(-), respectively. Although UV irradiation degraded RNZ more effectively than chlorination did, very low quantum yield of RNZ at 254 nm was obtained as 1.02 × 10(-3) mol E(-1). RNZ could be efficiently degraded and mineralized in the UV/chlorine process due to the generation of hydroxyl radicals. The second-order rate constant between RNZ and hydroxyl radical was determined as (2.92 ± 0.05) × 10(9) M(-1) s(-1). The degradation intermediates of RNZ during the three processes were identified with Ultra Performance Liquid Chromatography - Electrospray Ionization - mass spectrometry and the degradation pathways were then proposed. Moreover, the variation of chloropicrin (TCNM) and chloroform (CF) formation after the three processes were further evaluated. Enhanced formation of CF and TCNM precursors during UV/chlorine process deserves extensive attention in drinking water treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Case Study of Petroleum Degradation in Different Soil Textural Classes.

PubMed

Kogbara, Reginald B; Ayotamuno, Josiah M; Worlu, Daniel C; Fubara-Manuel, Isoteim

2016-01-01

Patents have been granted for a number of techniques for petroleum biodegradation including use of micro-organisms for degradation of hydrocarbon-based substances and for hydrocarbon degradation in oil reservoirs, but there is a dearth of information on hydrocarbon degradation in different soil textures. Hence, this work investigated the effects of different soil textures on degradation of petroleum hydrocarbons during a six-week period. Five soil textural classes commonly found in Port Harcourt metropolis, Nigeria, namely sand, loamy sand, sandy loam, silty clay and clay, were employed. The soils were contaminated with the same amount of crude oil and then remediated by biostimulation. Selected soil properties were monitored over time. Bacterial numbers declined significantly in the fine soil textures after petroleum contamination, but were either unaffected or increased significantly in the coarser soil textures. Hydrocarbon losses ranged from 42% - 99%; the sandy loam had the highest, while the clay soil had the least total hydrocarbon content (THC) reduction. The total heterotrophic bacterial (THB) counts generally corroborated the THC results. Fold increase in bacterial numbers due to remediation treatment decreased with increasing clay content. The results suggest that higher sand than clay content of soil favours faster hydrocarbon degradation. Hydrocarbon degradation efficiency increased with silt content among soil groupings such as fine and coarse soils but not necessarily with increasing silt content of soil. Thus, there seems to be cut-off sand and clay contents in soil at which the effect of the silt content becomes significant.

Zipper-interacting protein kinase is involved in regulation of ubiquitination of the androgen receptor, thereby contributing to dynamic transcription complex assembly.

PubMed

Felten, A; Brinckmann, D; Landsberg, G; Scheidtmann, K H

2013-10-10

We have recently identified apoptosis-antagonizing transcription factor (AATF), tumor-susceptibility gene 101 (TSG101) and zipper-interacting protein kinase (ZIPK) as novel coactivators of the androgen receptor (AR). The mechanisms of coactivation remained obscure, however. Here we investigated the interplay and interdependence between these coactivators and the AR using the endogenous prostate specific antigen (PSA) gene as model for AR-target genes. Chromatin immunoprecipitation in combination with siRNA-mediated knockdown revealed that recruitment of AATF and ZIPK to the PSA enhancer was dependent on AR, whereas recruitment of TSG101 was dependent on AATF. Association of AR and its coactivators with the PSA enhancer or promoter occurred in cycles. Dissociation of AR-transcription complexes was due to degradation because inhibition of the proteasome system by MG132 caused accumulation of AR at enhancer/promoter elements. Moreover, inhibition of degradation strongly reduced transcription, indicating that continued and efficient transcription is based on initiation, degradation and reinitiation cycles. Interestingly, knockdown of ZIPK by siRNA had a similar effect as MG132, leading to reduced transcription but enhanced accumulation of AR at androgen-response elements. In addition, knockdown of ZIPK, as well as overexpression of a dominant-negative ZIPK mutant, diminished polyubiquitination of AR. Furthermore, ZIPK cooperated with the E3 ligase Mdm2 in AR-dependent transactivation, assembled into a single complex on chromatin and phosphorylated Mdm2 in vitro. These results suggest that ZIPK has a crucial role in regulation of ubiquitination and degradation of the AR, and hence promoter clearance and efficient transcription.

Experimental characterization of a direct conversion amorphous selenium detector with thicker conversion layer for dual-energy contrast-enhanced breast imaging.

PubMed

Scaduto, David A; Tousignant, Olivier; Zhao, Wei

2017-08-01

Dual-energy contrast-enhanced imaging is being investigated as a tool to identify and localize angiogenesis in the breast, a possible indicator of malignant tumors. This imaging technique requires that x-ray images are acquired at energies above the k-shell binding energy of an appropriate radiocontrast agent. Iodinated contrast agents are commonly used for vascular imaging, and require x-ray energies greater than 33 keV. Conventional direct conversion amorphous selenium (a-Se) flat-panel imagers for digital mammography show suboptimal absorption efficiencies at these higher energies. We use spatial-frequency domain image quality metrics to evaluate the performance of a prototype direct conversion flat-panel imager with a thicker a-Se layer, specifically fabricated for dual-energy contrast-enhanced breast imaging. Imaging performance was evaluated in a prototype digital breast tomosynthesis (DBT) system. The spatial resolution, noise characteristics, detective quantum efficiency, and temporal performance of the detector were evaluated for dual-energy imaging for both conventional full-field digital mammography (FFDM) and DBT. The zero-frequency detective quantum efficiency of the prototype detector is improved by approximately 20% over the conventional detector for higher energy beams required for imaging with iodinated contrast agents. The effect of oblique entry of x-rays on spatial resolution does increase with increasing photoconductor thickness, specifically for the most oblique views of a DBT scan. Degradation of spatial resolution due to focal spot motion was also observed. Temporal performance was found to be comparable to conventional mammographic detectors. Increasing the a-Se thickness in direct conversion flat-panel imagers results in better performance for dual-energy contrast-enhanced breast imaging. The reduction in spatial resolution due to oblique entry of x-rays is appreciable in the most extreme clinically relevant cases, but may not profoundly affect reconstructed images due to the algorithms and filters employed. Degradation to projection domain spatial resolution is thus outweighed by the improvement in detective quantum efficiency for high-energy x-rays. © 2017 American Association of Physicists in Medicine.

Microbial degradation of 4-monobrominated diphenyl ether in an aerobic sludge and the DGGE analysis of diversity.

PubMed

Chen, Chun-Yao; Wang, Chun-Kang; Shih, Yang-Hsin

2010-07-01

Polybrominated diphenyl ethers (PBDEs) were applied as flame retardant additives in polymers for many plastic and electronic products. Due to their ubiquitous distribution in the environment, potential toxicity to human and tendency for bioaccumulation, PBDEs have raised public safety concern. In this study we examined the degradation of 4-monobrominated diphenyl ether (4-BDE) in aerobic sludge, as a model for PBDE biodegradation. Degradation of 4-BDE was observed in aerobic sludge. Co-metabolism with toluene or diphenyl ether facilitated 4-BDE biodegradation in terms of kinetics and efficiency. Diphenyl ether seems to perform slightly better as an auxiliary carbon source than toluene in facilitating 4-BDE degradation. During the experiment we identified diphenyl ether by gas chromatography/mass spectrometry(GC/MS), which indicates that an anaerobic debromination has occurred. Bacterial community composition was monitored with denaturing gradient gel electrophoresis. The fragments enriched in 4-BDE-degrading aerobic sludge samples belong to presumably a novel anaerobic Clostridiales species distantly related to all known debrominating microbes. This suggests that 4-BDE biodegradation can occur in anaerobic micro-niche in an apparently aerobic environment, by a previously unknown bacterial species. These findings can provide better understandings of biodegradation of brominated diphenyl ethers and can facilitate the prediction of the fate of PBDEs in the environment.

A New Synergetic Nanocomposite for Dye Degradation in Dark and Light

PubMed Central

V., Lakshmi Prasanna; Rajagopalan, Vijayaraghavan

2016-01-01

Environmental hazard caused due to the release of dyes in effluents is a concern in many countries. Among the various methods to combat this problem, Advanced Oxidation Process, in which semiconductor photocatalysts are used, is considered the most effective one. These materials release Reactive Oxygen Species (ROS) such as hydroxyl radical and superoxide in suspension that degrade the dyes into non-toxic minerals. However, this process requires visible or UV light for activation. Hence, there is a need to develop materials that release ROS, both in the absence and in the presence of light, so that the efficiency of dye removal is enhanced. Towards this objective, we have designed and synthesized a new nanocomposite ZnO2/polypyrrole which releases ROS even in the dark. The ROS released in the dark and in light were estimated by standard methods. It is to be noted that ZnO2 degrades the dye only under UV light but not in dark or in the presence of visible light. We propose the mechanism of dye degradation in dark and light. The synergically coupled nanocomposite of ZnO2/ppy is the first example that degrades dyes in the dark, through advanced oxidation process without employing additional reagents. PMID:27929084

Light-current-induced acceleration of degradation of methylammonium lead iodide perovskite solar cells

NASA Astrophysics Data System (ADS)

Xiang, Yuren; Zhang, Fan; He, Junjie; Lian, Jiarong; Zeng, Pengju; Song, Jun; Qu, Junle

2018-04-01

The photo-conversion efficiency of perovskite solar cells (PSCs) has been improved considerably in recent years, but the poor stability of PSCs still prevents their commercialization. In this report, we use the rate of the integrated short-circuit current change (Drate) to investigate the performance degradation kinetics and identify the degradation of PSCs that is accelerated by the light current. The value of Drate increases by an order of magnitude from about 0.02 to 0.35 mA cm-2·min-1 after light-IV testing. The accelerated degradation progress is proven to be dominated by the hydration process and the migration of the iodine ions of the light current. The migration of the iodine ions enhances the hydration process through a chain reaction, enabling the formation of fast diffusion channels for both H2O and O2, which induce the rapid decomposition of the perovskite film and increase the density of the trap state. The X-ray photoelectron spectroscopy measurement data also indicate that the super oxygen may be formed due to the PCBM damage caused by the migration iodine ions. An understanding of the degradation acceleration mechanism would provide an insight into the effect of ion migration on the stability of PSCs.

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

PubMed

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

1999-03-01

The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions.

Influence of UV lamp, sulfur(IV) concentration, and pH on bromate degradation in UV/sulfite systems: Mechanisms and applications.

PubMed

Xiao, Qian; Wang, Ting; Yu, Shuili; Yi, Peng; Li, Lei

2017-03-15

Bromate (BrO 3 - ) is a possible human carcinogen regulated worldwide at a strict standard of 10 μg/L in drinking water. Removal of BrO 3 - by advanced reduction processes (ARPs) has attracted much attention due to its high reduction efficiency and easier combination with ultraviolet (UV) disinfection. In this study, we employed a UV/sulfite process to degrade BrO 3 - and studied the effects of UV lamp, sulfur(IV) concentration, and pH on effectiveness of the system in degrading BrO 3 - . Low-pressure UV lamps (UV-L) instead of medium-pressure UV lamps (UV-M) were selected because of the high ultraviolet-C (UV-C) efficiency of UV-L. The increased sulfur(IV) concentration is proportionally correlated with enhanced degradation kinetics. BrO 3 - reduction was improved by increasing pH when pH is within 6.0-9.0, and principal component analysis demonstrated that pH is the most influential factor over sulfur(IV) concentration and type of UV lamp. Degradation mechanisms at different pH levels were subsequently investigated. Results showed that the reduction reactions are induced by hydrated electron (e aq - ) at pH > 9.0, by H at pH 4.0, and by both e aq - and H at pH 7.0. Effective quantum efficiency for the formation of e aq - and H in the photocatalytic systems was determined to be 0.109 ± 0.001 and 0.034 ± 0.001 mol E -1 , respectively. Furthermore, mass balance calculation of bromine and sulfur at pH 7 showed that bromide, sulfate and possibly dithionate ions were the major products, and a degradation pathway was proposed accordingly. Moreover, UV/sulfite processes could reduce the initial bromate concentration of 0.1 mM by 82% and 95% in the presence and absence of O 2 in tap water respectively, and 99% in the absence of O 2 in deionized water within 20 min at pH 9.0 and 2.0 mM sulfur (IV). Copyright © 2017 Elsevier Ltd. All rights reserved.

New insight of hybrid membrane to degrade Congo red and Reactive yellow under sunlight.

PubMed

Rajeswari, A; Jackcina Stobel Christy, E; Pius, Anitha

2018-02-01

A study was carried out to investigate the degradation of organic contaminants (Congo red and Reactive yellow - 105) using cellulose acetate - polystyrene (CA-PS) membrane with and without ZnO impregnation. Scanning electron microscope (SEM), electron dispersive analysis of X-rays (EDAX), Fourier transform infrared spectrometer (FTIR), atomic force microscope (AFM) and thermogravimeric analysis (TG-DTA) analysis were carried out to characterize bare and ZnO impregnated CA-PS membranes. Membrane efficiency was also tested for pure water flux and antifouling performance. The modified membrane showed almost 85% water flux recovery. Blending of ZnO nanoparticles to CA-PS matrix could decrease membrane fouling and increase permeation quality of the membrane with above 90% of photocatalytic degradation efficiency for dyes. The rate of degradation of dyes was observed using UV-Vis spectrometer. Reusability of CA-PS-ZnO membrane was studied and no significant change was noted in the degradation efficiency until fourth cycle. Langmuir-Hinshelwood kinetic model well describes the photo degradation capacity and the degradation of dyes CR and RY - 105 exhibited pseudo-first order kinetics. The regression coefficient (R) of CR and RY - 105 found to be 0.99. The novelty of the prepared CA-PS-ZnO membrane is that it has better efficiency and high thermal stability than our previously reported material. Therefore, ZnO impregnated CA-PS membrane had proved to be an innovative alternative for the degradation of CR and RY - 105 dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Realizing luminescent downshifting in ZnO thin films by Ce doping with enhancement of photocatalytic activity

NASA Astrophysics Data System (ADS)

Narayanan, Nripasree; Deepak, N. K.

2018-04-01

ZnO thin films doped with Ce at different concentration were deposited on glass substrates by spray pyrolysis technique. XRD analysis revealed the phase purity and polycrystalline nature of the films with hexagonal wurtzite geometry and the composition analysis confirmed the incorporation of Ce in the ZnO lattice in the case of doped films. Crystalline quality and optical transmittance diminished while electrical conductivity enhanced with Ce doping. Ce doping resulted in a red-shift of optical energy gap due to the downshift of the conduction band minimum after merging with Ce related impurity bands formed below the conduction band in the forbidden gap. In the room temperature photoluminescence spectra, UV emission intensity of the doped films decreased while the intensity of the visible emission band increased drastically implying the degradation in crystallinity as well as the incorporation of defect levels capable of luminescence downshifting. Ce doping showed improvement in photocatalytic efficiency by effectively trapping the free carriers and then transferring for dye degradation. Thus Ce doped ZnO thin films are capable of acting as luminescent downshifters as well as efficient photocatalysts.

CdS nanoparticles immobilized on porous carbon polyhedrons derived from a metal-organic framework with enhanced visible light photocatalytic activity for antibiotic degradation

NASA Astrophysics Data System (ADS)

Yang, Cao; Cheng, Jianhua; Chen, Yuancai; Hu, Yongyou

2017-10-01

The CdS/MOF-derived porous carbon (MPC) composite as an efficient visible-light-driven photocatalyst was prepared through the pyrolysis of ZIF-8 and subsequent growth of CdS. The porous and functionalized MPC enables intimate and discrete growth of CdS nanoparticles. This unique structure not only reduces the bulk recombination owing to nano-size effect of CdS, but also suppresses the surface recombination due to the discrete growth of CdS nanoparticles on MPC polyhedrons, which facilitates electron transfer and charge separation. Moreover, such a composite material possessed good adsorption ability toward the antibiotic pollutants because of the amino-functionalized surface. As a result, the as-prepared CdS/MPC composites showed excellent photocatalytic performance for the antibiotic degradation, significantly improving the photoactivity of CdS. Importantly, the CdS/MPC composite with the CdS loading of 20 wt% exhibited the highest photocatalytic efficiency of approximately 91% and apparent rate constant of 0.024 min-1.

Vortex Stabilized Plasma for Rapid Water Disinfection & Pharmaceutical Degradation

NASA Astrophysics Data System (ADS)

Hershcovitch, Ady

2016-10-01

Good quality drinking water is dwindling for large segments of the world population. Aggravating the problem is proliferation of antibiotics in the water supply, which give rise to drug resistant pathogens. One option for water supply increase is recycling waste and polluted water by inexpensive, environmentally friendly methods. Presently disinfection uses chemicals and UV radiation. Chemicals are limited by residual toxicity, while UV consumes much electricity. Current methods can remove only certain classes of drugs due to their large variety of physical and chemical properties. Plasmas in water are very attractive for degrading all pharmaceuticals and deactivating pathogens: intense arc current can physically break up any molecular bonds. UV radiation, ozone, etc. generation inside the water volume disinfects. Present utilized plasmas: glow, pulsed arcs are not power efficient; vortex stabilized plasmas are power efficient that can advance water treatment state-of-the-art by orders of magnitude. Proposed techniquefeatures novel components facilitating large diameter vortex stabilized in-water arcs with optimized plasma parameters for maximal UV-C emission; and harvests hydrogen centered by the vortex.

High resolution, low cost solar cell contact development

NASA Technical Reports Server (NTRS)

Mardesich, N.

1979-01-01

The experimental work demonstrating the feasibility of the MIDFILM process as a low cost means of applying solar cell collector metallization as reported. Cell efficiencies of above 14% (AMl, 28 C) were achieved with fritted silver metallization. Environmental tests suggest that the metallization is slightly humidity sensitive and degradation is observed on cells with high series resistance. The major yield loss in the fabrication of cells was due to discontinuous grid lines, resulting in high series resitance. Standard lead-tin solder plated interconnections do not appear compatible with the MIDFILM contact. Copper, nickel and molybdemun base powder were investigated as low cost metallization systems. The copper based powder degraded the cell response. The nickel and molybdenum base powders oxidized when sintered in the oxidizing atmosphere necessary to ash the photoresin.

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

NASA Astrophysics Data System (ADS)

López-Ballesteros, Ana; Oyonarte, Cecilio; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Rosario Moya, M.; Domingo, Francisco

2018-01-01

Currently, drylands occupy more than one-third of the global terrestrial surface and are recognized as areas vulnerable to land degradation. The concept of land degradation stems from the loss of an ecosystem's biological productivity due to long-term loss of natural vegetation or depletion of soil nutrients. Drylands' key role in the global carbon (C) balance has been recently demonstrated, but the effects of land degradation on C sequestration by these ecosystems still need to be investigated. In the present study, we compared net C and water vapor fluxes, together with satellite, meteorological and vadose zone (CO2, water content and temperature) measurements, between two nearby (˜ 23 km) experimental sites representing natural (i.e., site of reference) and degraded grazed semiarid grasslands. We utilized data acquired over 6 years from two eddy covariance stations located in southeastern Spain with highly variable precipitation magnitude and distribution. Results show a striking difference in the annual C balances with an average net CO2 exchange of 196 ± 40 (C release) and -23 ± 2 g C m-2 yr-1 (C fixation) for the degraded and natural sites, respectively. At the seasonal scale, differing patterns in net CO2 fluxes were detected over both growing and dry seasons. As expected, during the growing seasons, greater net C uptake over longer periods was observed at the natural site. However, a much greater net C release, probably derived from subterranean ventilation, was measured at the degraded site during drought periods. After subtracting the nonbiological CO2 flux from net CO2 exchange, flux partitioning results point out that, during the 6 years of study, gross primary production, ecosystem respiration and water use efficiency were, on average, 9, 2 and 10 times higher, respectively, at the natural site versus the degraded site. We also tested differences in all monitored meteorological and soil variables and CO2 at 1.50 m belowground was the variable showing the greatest intersite difference, with ˜ 1000 ppm higher at the degraded site. Thus, we believe that subterranean ventilation of this vadose zone CO2, previously observed at both sites, partly drives the differences in C dynamics between them, especially during the dry season. It may be due to enhanced subsoil-atmosphere interconnectivity at the degraded site.

Direct evaluation of influence of electron damage on the subcell performance in triple-junction solar cells using photoluminescence decays.

PubMed

Tex, David M; Nakamura, Tetsuya; Imaizumi, Mitsuru; Ohshima, Takeshi; Kanemitsu, Yoshihiko

2017-05-16

Tandem solar cells are suited for space applications due to their high performance, but also have to be designed in such a way to minimize influence of degradation by the high energy particle flux in space. The analysis of the subcell performance is crucial to understand the device physics and achieve optimized designs of tandem solar cells. Here, the radiation-induced damage of inverted grown InGaP/GaAs/InGaAs triple-junction solar cells for various electron fluences are characterized using conventional current-voltage (I-V) measurements and time-resolved photoluminescence (PL). The conversion efficiencies of the entire device before and after damage are measured with I-V curves and compared with the efficiencies predicted from the time-resolved method. Using the time-resolved data the change in the carrier dynamics in the subcells can be discussed. Our optical method allows to predict the absolute electrical conversion efficiency of the device with an accuracy of better than 5%. While both InGaP and GaAs subcells suffered from significant material degradation, the performance loss of the total device can be completely ascribed to the damage in the GaAs subcell. This points out the importance of high internal electric fields at the operating point.

Pharmaceutical Applications of Nanoparticle Carriers

NASA Astrophysics Data System (ADS)

Heurtault, B.; Schuber, F.; Frisch, B.

Once it has been administered, an active principle still has to face many physiological barriers on the way to its target, and this may significantly affect its efficiency. These different barriers depend to a great extent on the active ingredient itself and on the way it is administered. They may be constituted by enzymes, an acidic or basic pH, or cell membranes that must be crossed. As a consequence, the active principle may be degraded or distributed to organs other than the therapeutic target. This can reduce the efficiency of the administered dose, or even lead to toxicity with regard to organs other than the target. For example, this situation is observed in trials for the oral administration of insulin (for treating type I diabetes). One point is that this molecule is weakly absorbed by the digestive epithelium (first barrier). Secondly, it undergoes enzymatic degradation by gastric proteases (second barrier). As a consequence, the free form of the molecule cannot be administered orally. This is why insulin is mainly administered subcutaneously, so that it attains the blood circulation directly. However, such a means of administration requires specific training of the patient. This example shows that lack of efficiency and/or difficulties in using certain molecules are not necessarily due to their pharmacology, but rather in some cases to their physicochemical properties.

Common Methodology for Efficient Airspace Operations

NASA Technical Reports Server (NTRS)

Sridhar, Banavar

2012-01-01

Topics include: a) Developing a common methodology to model and avoid disturbances affecting airspace. b) Integrated contrails and emission models to a national level airspace simulation. c) Developed capability to visualize, evaluate technology and alternate operational concepts and provide inputs for policy-analysis tools to reduce the impact of aviation on the environment. d) Collaborating with Volpe Research Center, NOAA and DLR to leverage expertise and tools in aircraft emissions and weather/climate modeling. Airspace operations is a trade-off balancing safety, capacity, efficiency and environmental considerations. Ideal flight: Unimpeded wind optimal route with optimal climb and descent. Operations degraded due to reduction in airport and airspace capacity caused by inefficient procedures and disturbances.

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.

Degradation of natural organic matter by UV/chlorine oxidation: Molecular decomposition, formation of oxidation byproducts and cytotoxicity.

PubMed

Wang, Wen-Long; Zhang, Xue; Wu, Qian-Yuan; Du, Ye; Hu, Hong-Ying

2017-11-01

The degradation of natural organic matters (NOMs) by the combination of UV and chlorine (UV/chlorine) was investigated in this study. UV/chlorine oxidation can effectively degrade NOMs, with the degradation of chromophores (∼80%) and fluorophores (76.4-80.8%) being more efficient than that of DOC (15.1-18.6%). This effect was attributed to the chromophores and fluorophores (double bonds, aromatic groups and phenolic groups) being preferentially degraded by UV/chlorine oxidation, particularly reactive groups with high electron donating capacity. Radical species •OH and •Cl were generated during UV/chlorine oxidation, with the contribution of •OH 1.4 times as high as that of •Cl. The degradation kinetics of different molecular weight (MW) fractions suggests that UV/chlorine oxidation degrades high MW fractions into low MW fractions, with the degradation rates of high MW fractions (>3000 Da) 4.5 times of those of medium MW fractions (1000-3000 Da). In comparison with chlorination alone, UV/chlorine oxidation did not increase the formation (30 min) and formation potential (24 h) of trihalomethanes, but instead promoted the formation and formation potential of haloacetic acids and chloral hydrate. Adsorbable organic halogen (AOX) formed from UV/chlorine oxidation of NOM were 0.8 times higher than those formed from chlorination. Cytotoxicity studies indicated that the cytotoxicity of NOM increased after both chlorination and UV/chlorine oxidation, which may be due to the formation of AOX. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterization of novel plasmonic Ag/AgX-CNTs (X = Cl, Br, I) nanocomposite photocatalysts and synergetic degradation of organic pollutant under visible light.

PubMed

Shi, Huixian; Chen, Jiangyao; Li, Guiying; Nie, Xin; Zhao, Huijun; Wong, Po-Keung; An, Taicheng

2013-08-14

A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition-precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, scanning electron microscopy, and ultraviolet-visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.

Method of restoring degraded solar cells

DOEpatents

Staebler, David L.

1983-01-01

Amorphous silicon solar cells have been shown to have efficiencies which degrade as a result of long exposure to light. Annealing such cells in air at a temperature of about 200.degree. C. for at least 30 minutes restores their efficiency.

Visual signal detection in structured backgrounds. II. Effects of contrast gain control, background variations, and white noise

NASA Technical Reports Server (NTRS)

Eckstein, M. P.; Ahumada, A. J. Jr; Watson, A. B.

1997-01-01

Studies of visual detection of a signal superimposed on one of two identical backgrounds show performance degradation when the background has high contrast and is similar in spatial frequency and/or orientation to the signal. To account for this finding, models include a contrast gain control mechanism that pools activity across spatial frequency, orientation and space to inhibit (divisively) the response of the receptor sensitive to the signal. In tasks in which the observer has to detect a known signal added to one of M different backgrounds grounds due to added visual noise, the main sources of degradation are the stochastic noise in the image and the suboptimal visual processing. We investigate how these two sources of degradation (contrast gain control and variations in the background) interact in a task in which the signal is embedded in one of M locations in a complex spatially varying background (structured background). We use backgrounds extracted from patient digital medical images. To isolate effects of the fixed deterministic background (the contrast gain control) from the effects of the background variations, we conduct detection experiments with three different background conditions: (1) uniform background, (2) a repeated sample of structured background, and (3) different samples of structured background. Results show that human visual detection degrades from the uniform background condition to the repeated background condition and degrades even further in the different backgrounds condition. These results suggest that both the contrast gain control mechanism and the background random variations degrade human performance in detection of a signal in a complex, spatially varying background. A filter model and added white noise are used to generate estimates of sampling efficiencies, an equivalent internal noise, an equivalent contrast-gain-control-induced noise, and an equivalent noise due to the variations in the structured background.

Study on effects of temperature, moisture and pH in degradation and degradation kinetics of aldrin, endosulfan, lindane pesticides during full-scale continuous rotary drum composting.

PubMed

Ali, Muntjeer; Kazmi, A A; Ahmed, Naseem

2014-05-01

Study focused on effects of temperature, moisture and pH on degradation and degradation kinetics of aldrin, endosulfan (α), endosulfan (β) and lindane during vegetable waste composting using full-scale continuous rotary drum composter (FSCRDC). Extraction, concentration and quantification of pesticides were made from waste material at different stages by ultra-sonification, silica gel column and GC-MS analysis. Removal efficiency of aldrin, endosulfan α, endosulfan β and lindane was found 85.67%, 84.95%, 83.20% and 81.36% respectively due to optimum temperature, moisture, pH and enhanced microbial activity. Maximum temperature in inlet zone was found 60-65°C which is most suitable for complex microbial population. After feeding and turning in inlet zone, temperature reduced to 38°C from 60 to 65°C and regained it within 7-8h, and pH reduced to 5.3±0.2 from 7.5±0.3 in 4h and regained it in 10h. Heterotrophic bacteria Bacillus sp., Pseudomonas sp. and Lactobacillus sp. also decreased from 4.4×10(3) to 7.80×10(2)CFU g(-1) in 2 h due to gradual variation in temperature and pH. No significant temperature change was found in middle and outlet zones during feeding and turning. Degradation of pesticides was observed as first order kinetics and half-life of aldrin, endosulfan α, endosulfan β and lindane was reduced to 25.54, 18.43, 18.43 and 27.43 d from 1095, 60, 270 and 160 d respectively. Thus, the observations in contrast of removal and degradation kinetics of organochlorine pesticides residues in vegetable waste though full-scale rotary drum composting proved it the best suited technique. Copyright © 2014 Elsevier Ltd. All rights reserved.

Degradation of polycyclic aromatic hydrocarbons (PAHs) present in used motor oil and implications for urban runoff quality

NASA Astrophysics Data System (ADS)

Ferreira, M.; Stenstrom, M. K.; Lau, S.

2013-12-01

Polycyclic aromatic hydrocarbons (PAHs) are common organic pollutants of urban stormwater runoff due to atmospheric deposition, vehicle-related discharges, and coal tar pavement sealants. The US EPA lists sixteen PAHs as priority pollutants and seven of those are potential carcinogenic compounds. Due to their molecular structure, PAHs tend to attach to particles that will subsequently be deposited as sediments in waterways. This study focuses on the degradation of PAHs present in used motor oil. Four experimental setups were used to simulate volatilization and photooxidation in the degradation of sixteen PAHs as observed for up to 54 days. The volatilization-only experiment showed substantial reduction only in the concentration of Napthalene (Nap). However, photooxidation-only was more efficient in degrading PAHs. In this process, substantial reduction in the concentrations of Nap, Acenapthene (Anthe), Anthracene (ANT), Fluoranthene (FLT), Pyrene (PYR), Benz[a]anthracene (BaA), Benzo[a]pyrene (BaP), Indeno[1,2,3,cd]pyrene (INP), and Benz[g,h,i]perylene (BghiP) were observed as early as five days. The two volatilization-photooxidation experiments exhibited substantial reduction in the concentrations of Fluorene (FLU), Chrysene (CHR) and Benzo[b]fluoranthene (BbF), in addition to the PAHs reduced by photooxidation-only. Phenanthrene (PHE), Fluoranthene (FLT), and Benzo[b]fluoranthene (BbF) only exhibited substantial decreased concentrations after 20 days in the volatilization-photooxidation experiment. One PAH, acenapthylene (Anthy), was not detected in the original sample of used motor oil. The highest degradations were observed in the combined volatilization-photooxidation experiment. In regions with infrequent rainfall, such as Southern California, molecules of PAHs attached to highway particles will have time to undergo degradation prior to transport. Therefore, PAHs may be present in lower concentrations in highway runoff in dry climates than in rainy climates. To support this hypothesis, a review of highway-related PAHs concentrations is presented.

Heparin-based hydrogels with tunable sulfation & degradation for anti-inflammatory small molecule delivery.

PubMed

Peng, Yifeng; Tellier, Liane E; Temenoff, Johnna S

2016-08-16

Sustained release of anti-inflammatory agents remains challenging for small molecule drugs due to their low molecular weight and hydrophobicity. Therefore, the goal of this study was to control the release of a small molecule anti-inflammatory agent, crystal violet (CV), from hydrogels fabricated with heparin, a highly sulfated glycosaminoglycan capable of binding positively-charged molecules such as CV. In this system, both electrostatic interactions between heparin and CV and hydrogel degradation were tuned simultaneously by varying the level of heparin sulfation and varying the amount of dithiothreitol within hydrogels, respectively. It was found that heparin sulfation significantly affected CV release, whereby more sulfated heparin hydrogels (Hep and Hep(-N)) released CV with near zero-order release kinetics (R-squared values between 0.96-0.99). Furthermore, CV was released more quickly from fast-degrading hydrogels than slow-degrading hydrogels, providing a method to tune total CV release between 5-15 days while maintaining linear release kinetics. In particular, N-desulfated heparin hydrogels exhibited efficient CV loading (∼90% of originally included CV), near zero-order CV release kinetics, and maintenance of CV bioactivity after release, making this hydrogel formulation a promising CV delivery vehicle for a wide range of inflammatory diseases.

Electrospray ionization mass spectrometry of the photodegradation of naphthenic acids mixtures irradiated with titanium dioxide.

PubMed

Headley, John V; Du, Jing-Long; Peru, Kerry M; McMartin, Dena W

2009-05-01

Electrospray ionization mass spectrometry was used to study the photodegradation of an oil sands naphthenic acid (NA) mixture, a commercial Fluka NA mixture and a candidate NA, 4-Methyl-cyclohexaneaceticic acid (4-MCHAA) irradiated with TiO(2) (P25) suspension under both fluorescent and natural sunlight. Under natural sunlight irradiation over the TiO(2) suspension, approximately 75% of compounds in the NA mixtures and 100% of 4-MCHAA were degraded in 8 h. No degradation was observed under dark conditions, regardless of the presence or absence of TiO(2). The structural formula of the NAs is given by C(n)H(2n + z)O(2), where n represents the carbon number and z specifies a homologous family with 0-6 rings (z = 0 to -12). The degree of degradation was noted to vary among the NA mixtures and the candidate NA compound with more efficient degradation achieved for molecules with -z values from 0 to 6. The difference in the efficacy of the photocatalysis was likely due to the structure and size of the compounds. In the case of -z = 6 to 12, steric constraints are a key factor what hinders photocatalysis.

454-Pyrosequencing analysis of highly adapted azo dye-degrading microbial communities in a two-stage anaerobic-aerobic bioreactor treating textile effluent.

PubMed

Köchling, Thorsten; Ferraz, Antônio Djalma Nunes; Florencio, Lourdinha; Kato, Mario Takayuki; Gavazza, Sávia

2017-03-01

Azo dyes, which are widely used in the textile industry, exhibit significant toxic characteristics for the environment and the human population. Sequential anaerobic-aerobic reactor systems are efficient for the degradation of dyes and the mineralization of intermediate compounds; however, little is known about the composition of the microbial communities responsible for dye degradation in these systems. 454-Pyrosequencing of the 16S rRNA gene was employed to assess the bacterial biodiversity and composition of a two-stage (anaerobic-aerobic) pilot-scale reactor that treats effluent from a denim factory. The anaerobic reactor was inoculated with anaerobic sludge from a domestic sewage treatment plant. Due to the selective composition of the textile wastewater, after 210 days of operation, the anaerobic reactor was dominated by the single genus Clostridium, affiliated with the Firmicutes phylum. The aerobic biofilter harbored a diverse bacterial community. The most abundant phylum in the aerobic biofilter was Proteobacteria, which was primarily represented by the Gamma, Delta and Epsilon classes followed by Firmicutes and other phyla. Several bacterial genera were identified that most likely played an essential role in azo dye degradation in the investigated system.

Investigation of the persistence of nerve agent degradation analytes on surfaces through wipe sampling and detection with ultrahigh performance liquid chromatography-tandem mass spectrometry.

PubMed

Willison, Stuart A

2015-01-20

The persistence of chemical warfare nerve agent degradation analytes on surfaces is important, from indicating the presence of nerve agent on a surface to guiding environmental restoration of a site after a release. Persistence was investigated for several chemical warfare nerve agent degradation analytes on indoor surfaces and presents an approach for wipe sampling of surfaces, followed by wipe extraction and liquid chromatography-tandem mass spectrometry detection. Commercially available wipe materials were investigated to determine optimal wipe recoveries. Tested surfaces included porous/permeable (vinyl tile, painted drywall, and wood) and largely nonporous/impermeable (laminate, galvanized steel, and glass) surfaces. Wipe extracts were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). UPLC provides a separation of targeted degradation analytes in addition to being nearly four times faster than high-performance liquid chromatography, allowing for greater throughput after a large-scale contamination incident and subsequent remediation events. Percent recoveries from nonporous/impermeable surfaces were 60-103% for isopropyl methylphosphonate (IMPA), GB degradate; 61-91% for ethyl methylphosphonate (EMPA), VX degradate; and 60-98% for pinacolyl methylphosphonate (PMPA), GD degradate. Recovery efficiencies for methyl phosphonate (MPA), nerve agent degradate, and ethylhydrogen dimethylphosphonate (EHDMAP), GA degradate, were lower, perhaps due to matrix effects. Diisopropyl methylphosphonate, GB impurity, was not recovered from surfaces. The resulting detection limits for wipe extracts were 0.065 ng/cm(2) for IMPA, 0.079 ng/cm(2) for MPA, 0.040 ng/cm(2) for EMPA, 0.078 ng/cm(2) for EHDMAP, and 0.013 ng/cm(2) for PMPA. The data indicate that laboratories may hold wipe samples for up to 30 days prior to analysis. Target analytes were observed to persist on surfaces for at least 6 weeks.

Photocatalytic and Photoelectrochemically Degradation of Chlorsulfuron herbicide

NASA Astrophysics Data System (ADS)

Guo, Xu; Liu, Hongwei; Miao, Jinjie; Ma, Zhen

2017-12-01

Photocatalytic and photo electrochemical (PEC) degradation of chlorsulfuron herbicide were studied. Two novel PEC electrodes Ti/IrO2-Pt-WO3 (TIW) and Ti/IrO2-Pt-Ag3PO4 (TIA) were designed and some important factors were studied. Lower current density showed lower removal efficiency than higher conditions by electrochemical method. Furthermore, PEC showed higher degradation efficiency than the sum of individual EO and photocatalytic methode.

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

PubMed

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

2012-07-01

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

Smart Carbon Nanotubes with Laser-Controlled Behavior in Gene Delivery and Therapy through a Non-Digestive Trafficking Pathway.

PubMed

Kong, Fenfen; Liu, Fei; Li, Wei; Guo, Xiaomeng; Wang, Zuhua; Zhang, Hanbo; Li, Qingpo; Luo, Lihua; Du, Yongzhong; Jin, Yi; You, Jian

2016-12-01

Near-infrared (NIR) laser-controlled gene delivery presents some benefits in gene therapy, inducing enhanced gene transfection efficiency. In this study, a "photothermal transfection" agent is obtained by wrapping poly(ethylenimine)-cholesterol derivatives (PEI-Chol) around single-walled carbon nanotubes (SWNTs). The PEI-Chol modified SWNTs (PCS) are effective in compressing DNA molecules and protecting them from DNaseI degradation. Compared to the complexes formed by PEI with DNA (PEI/DNA), complexes of PCS and DNA that are formed (PCS/DNA) exhibit a little lower toxicity to HEK293 and HeLa cells under the same PEI molecule weight and weight ratios. Notably, caveolae-mediated cellular uptake of PCS/DNA occurs, which results in a safer intracellular transport of the gene due to the decreased lysosomal degradation in comparison with that of PEI/DNA whose internalization mainly depends on clathrin rather than caveolae. Furthermore, unlike PEI/DNA, PCS/DNA exhibits a photothermal conversion ability, which promotes DNA release from PCS under NIR laser irradiation. The NIR laser-mediated photothermal transfection of PCS 10K /plasmid TP53 (pTP53) results in more apoptosis and necrosis of HeLa cells in vitro than other groups, and achieves a higher tumor-growth inhibition in vivo than naked pTP53, PEI 25K /pTP53, and PCS 10K /pTP53 alone. The enhanced transfection efficiency of PCS/DNA can be attributed to more efficient DNA internalization into the tumor cells, promotes detachment of DNA from PCS under the mediation of NIR laser and higher DNA stability in the cells due to caveolae-mediated cellular uptake of the complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method of restoring degraded solar cells

DOEpatents

Staebler, D.L.

1983-02-01

Amorphous silicon solar cells have been shown to have efficiencies which degrade as a result of long exposure to light. Annealing such cells in air at a temperature of about 200 C for at least 30 minutes restores their efficiency. 2 figs.

Bioremediation of polycyclic aromatic hydrocarbon (PAH) compounds: (acenaphthene and fluorene) in water using indigenous bacterial species isolated from the Diep and Plankenburg rivers, Western Cape, South Africa.

PubMed

Alegbeleye, Oluwadara Oluwaseun; Opeolu, Beatrice Olutoyin; Jackson, Vanessa

This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa and their ability to degrade two PAH compounds: acenaphthene and fluorene. A total of 19 bacterial isolates were obtained from the Diep and Plankenburg rivers among which four were identified as acenaphthene and fluorene degrading isolates. In simulated batch scale experiments, the optimum temperature for efficient degradation of both compounds was determined in a shaking incubator after 14 days, testing at 25°C, 30°C, 35°C, 37°C, 38°C, 40°C and 45°C followed by experiments in a Stirred Tank Bioreactor using optimum temperature profiles from the batch experiment results. All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded both compounds at 37°C, 37°C, 30°C and 35°C respectively. The degradation of fluorene was more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila degraded a mean total of 98.60%, 95.70%, 90.20% and 99.90% acenaphthene, respectively and 99.90%, 97.90%, 98.40% and 99.50% fluorene, respectively. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and may be used on a larger, commercial scale to bioremediate PAH contaminated river systems. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Optimization of Enterobacter cloacae (KU923381) for diesel oil degradation using response surface methodology (RSM).

PubMed

Ramasamy, Sugumar; Arumugam, Arumugam; Chandran, Preethy

2017-02-01

Efficiency of Enterobacter cloacae KU923381 isolated from petroleum hydrocarbon contaminated soil was evaluated in batch culture and bioreactor mode. The isolate were screened for biofilm formation using qualitative and quantitative assays. Response surface methodology (RSM) was used to study the effect of pH, temperature, glucose concentration, and sodium chloride on diesel degradation. The predicted values for diesel oil degradation efficiency by the statistical designs are in a close agreement with experimental data (R 2 = 99.66%). Degradation efficiency is increased by 36.78% at pH = 7, temperature = 35°C, glucose = 5%, and sodium chloride concentration = 5%. Under the optimized conditions, the experiments were performed for diesel oil degradation by gas chromatographic mass spectrometric analysis (GC-MS). GC-MS analysis confirmed that E. cloacae had highly degrade hexadecane, heptadecane, tridecane, and docosane by 99.71%, 99.23%, 99.66%, and 98.34% respectively. This study shows that rapid bioremoval of hydrocarbons in diesel oil is acheived by E. cloacae with abet of biofilm formation. The potential use of the biofilms for preparing trickling filters (gravel particles) for the degradation of hydrocarbons from petroleum wastes before their disposal in the open environment is highly suggested. This is the first successful attempt for artificially establishing petroleum hydrocarbon degrading bacterial biofilm on solid substrates in bioreactor.

Photocatalytic degradation of pentachlorophenol by visible light Ν-F-TiO₂ in the presence of oxalate ions: optimization, modeling, and scavenging studies.

PubMed

Antonopoulou, M; Konstantinou, I

2015-06-01

The efficiency of heterogeneous photocatalysis using N-F-TiO2 as photocatalyst to degrade a priority pollutant, pentachlorophenol (PCP), in the presence of oxalates (OA) was investigated in detail. Response surface methodology was used to optimize the effect of three variables (catalyst concentration, OA/PCP ratio, and pH) on the photocatalytic degradation of pentachlorophenol. A quadratic model was established as a functional relationship between three independent variables and the degradation efficiency of PCP. The results of model fitting and statistical analysis demonstrated that the pH played a key role in the degradation of PCP. Within the studied experimental ranges, the optimum conditions for maximum PCP degradation efficiency (97.5 %) were: catalyst concentration 600 mg L(-1), OA/PCP ratio 2, and pH 10. The contribution of HO(·), O2 (·-), and e(-) produced during the photocatalytic treatment was investigated with the addition of scavengers. The photocatalytic degradation was essentially proceeded through an oxidative mechanism at both acid and alkaline pH values by HO(.) and O2 (·-) radicals attack. It was found that O2 (·-) were the major reactive species involved in PCP degradation in pH 4 and HO(·) in pH 10.

Degradation of 3,3'-iminobis-propanenitrile in aqueous solution by Fe(0)/GAC micro-electrolysis system.

PubMed

Lai, Bo; Zhou, Yuexi; Yang, Ping; Yang, Jinghui; Wang, Juling

2013-01-01

The degradation of 3,3'-iminobis-propanenitrile was investigated using the Fe(0)/GAC micro-electrolysis system. Effects of influent pH value, Fe(0)/GAC ratio and granular activated carbon (GAC) adsorption on the removal efficiency of the pollutant were studied in the Fe(0)/GAC micro-electrolysis system. The degradation of 3,3'-iminobis-propanenitrile was affected by influent pH, and a decrease of the influent pH values from 8.0 to 4.0 led to the increase of degradation efficiency. Granular activated carbon was added as cathode to form macroscopic galvanic cells between Fe(0) and GAC and enhance the current efficiency of the Fe(0)/GAC micro-electrolysis system. The GAC could only adsorb the pollutant and provide buffer capacity for the Fe(0)/GAC micro-electrolysis system, and the macroscopic galvanic cells of the Fe(0)/GAC micro-electrolysis system played a leading role in degradation of 3,3'-iminobis-propanenitrile. With the analysis of the degradation products with GC-MS, possible reaction pathway for the degradation of 3,3'-iminobis-propanenitrile by the Fe(0)/GAC micro-electrolysis system was suggested. Copyright © 2012 Elsevier Ltd. All rights reserved.

Interfacial hydrothermal synthesis of SnO{sub 2} nanorods towards photocatalytic degradation of methyl orange

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

Hou, L.R., E-mail: houlr629@163.com; Lian, L.; Zhou, L.

2014-12-15

Highlights: • Efficient interfacial hydrothermal strategy was developed. • 1D SnO{sub 2} nanorods as an advanced photocatalyst. • SnO{sub 2} nanorods exhibit photocatalytic degradation of the MO. - Abstract: One-dimensional (1D) SnO{sub 2} nanorods (NRs) have been successfully synthesized by means of an efficient interfacial hydrothermal strategy. The resulting product was physically characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, etc. The as-fabricated SnO{sub 2} NRs exhibited excellent photocatalytic degradation of the methyl orange with high degradation efficiency of 99.3% with only 60 min ultra violet light irradiation. Meanwhile, the 1D SnO{sub 2} NRs exhibited intriguing photostabilitymore » after four recycles.« less

Enhanced organic pollutants degradation and electricity production simultaneously via strengthening the radicals reaction in a novel Fenton-photocatalytic fuel cell system.

PubMed

Zhao, Kai; Zeng, Qingyi; Bai, Jing; Li, Jinhua; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

2017-01-01

An enhanced result in organic pollutants degradation and simultaneous electricity production has been achieved by establishing a novel Fenton-photocatalytic fuel cell (Fenton-PFC) system in which TiO 2 nanotube arrays (TNA) was designed as a photoanode and ferrous ions were added. The proposed Fenton-PFC system can expand the radical reaction for organic pollutants degradation from the surface of electrodes to the whole solution system due to a continuous photoelectric Fenton reaction without continually adding any external voltage and ferrous ions. The cyclic reactions between ferrous ions (Fe 2+ /Fe 3+ ) and radicals and related species (HO, HO 2 , O 2 - and H 2 O 2 etc.) can be achieved at electrodes surface via a self-bias voltage yielded by the PFC. More importantly, the proposed Fenton-PFC system has hardly any sludge due to an effective radical reaction using a small amount of ferrous ions. The degradation rate of refractory organics, such as methyl orange, methylene blue, congo red and tetracycline, increased from 34.99%, 43.75%, 40.58% and 34.40% (the traditional PFC without Fe 2+ ) to 97.34%, 95.36%, 93.23% and 73.80% (the Fenton-PFC within Fe 2+ ) respectively after 60 min operation. Meanwhile, the electricity generation is up to 1.21-2.04 times larger than the traditional PFC. The proposed Fenton-PFC system provides a more economical and efficient way for energy recovery and wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photocatalytic degradation of leather dye over ZnO catalyst supported on alumina and glass surfaces.

PubMed

Sakthivel, S; Neppoiian, B; Palanichamy, M; Arabindoo, B; Murugesan, V

2001-01-01

The photocatalytic degradation of leather dye, Acid green 16, has been investigated over a ZnO catalyst supported on two different materials, namely alumina and glass beads (3-5 mm diameter). Sunlight was used as the energy source. The alumina-supported ZnO outperformed the glass-supported ZnO under identical operational conditions suggesting that the dye molecules are adsorbed on the alumina supports to make a high concentration environment around the loaded ZnO. The degradation efficiency was greater at pH = 4 compared to other acidic and neutral pH. Also, the degradation efficiency was a little bit higher in alkaline medium, which correlates with the adsorption behaviour of acid green 16 on the alumina supported ZnO. The influence of inorganic oxidants like H2O2, FeCl3 and Fenton reagent on the degradation efficiency were systematically studied. The decolourisation and extent of degradation of the dye were determined by UV-VIS spectroscopy and COD reflux methods, respectively. Complete mineralisation of the dye was conformed by High performance liquid chromatography (HPLC) analysis.

Analysis of twelve-month degradation in three polycrystalline photovoltaic modules

NASA Astrophysics Data System (ADS)

Lai, T.; Potter, B. G.; Simmons-Potter, K.

2016-09-01

Polycrystalline silicon photovoltaic (PV) modules have the advantage of lower manufacturing cost as compared to their monocrystalline counterparts, but generally exhibit both lower initial module efficiencies and more significant early-stage efficiency degradation than do similar monocrystalline PV modules. For both technologies, noticeable deterioration in power conversion efficiency typically occurs over the first two years of usage. Estimating PV lifetime by examining the performance degradation behavior under given environmental conditions is, therefore, one of continual goals for experimental research and economic analysis. In the present work, accelerated lifecycle testing (ALT) on three polycrystalline PV technologies was performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability, providing an illumination uniformity of 98% over a 2 x 1.6m area. In order to investigate environmental aging effects, timedependent PV performance (I-V characteristic) was evaluated over a recurring, compressed day-night cycle, which simulated local daily solar insolation for the southwestern United States, followed by dark (night) periods. During a total test time of just under 4 months that corresponded to a year equivalent exposure on a fielded module, the temperature and humidity varied in ranges from 3°C to 40°C and 5% to 85% based on annual weather profiles for Tucson, AZ. Removing the temperature de-rating effect that was clearly seen in the data enabled the computation of normalized efficiency degradation with time and environmental exposure. Results confirm the impact of environmental conditions on the module long-term performance. Overall, more than 2% efficiency degradation in the first year of usage was observed for all thee polycrystalline Si solar modules. The average 5-year degradation of each PV technology was estimated based on their determined degradation rates.

Effects of wavelength and water quality on photodegradation of N-Nitrosodimethylamine (NDMA).

PubMed

Sakai, Hiroshi; Takamatsu, Tatsuro; Kosaka, Koji; Kamiko, Naoyuki; Takizawa, Satoshi

2012-10-01

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that yields a cancer risk of 10(-6) at concentrations as low as 0.7 ng L(-1). Tentative guideline values are set at 3 ng L(-1) in California, USA; 9 ng L(-1) in Ontario, Canada; 40 ng L(-1) nationwide in Canada; and 100 ng L(-1) by the World Health Organization. NDMA is a great concern in treating reclaimed water as well as drinking water. UV degradation can be considered effective degradation method. A 1-log reduction of NDMA is achieved by 1000 mJ cm(-2) of a 254-nm low pressure (LP) mercury UV lamp. However, a higher degradation efficiency than that provided by LP lamps is desired in practical treatment. In this study, the effects of wavelength and water quality were investigated to achieve higher degradation efficiency. The effects of wavelength were examined by comparing three UV lamps: a 222-nm Kr Cl Excimer UV lamp, a 254-nm LP mercury UV lamp, and a 230- to 270-nm filtered medium pressure (FMP) mercury UV lamp. The 222-nm lamp and FMP lamp achieved 4 times and 2.8 times higher degradation efficiency, respectively, than the conventional 254-nm LP lamp. Effects on water quality were also simulated by using absorption spectrum data of nitrate solutions and process water from a drinking-water treatment plant. In the simulation, the 222-nm lamp was affected by UV-absorbing compounds in the water, whereas the FMP lamp showed more stable degradation efficiency. Appropriate use of these three types of lamps could enhance the efficiency of degradation of NDMA. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Device Engineering and Degradation Mechanism Study of All-Phosphorescent White Organic Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Xu, Lisong

As a possible next-generation solid-state lighting source, white organic light-emitting diodes (WOLEDs) have the advantages in high power efficiency, large area and flat panel form factor applications. Phosphorescent emitters and multiple emitting layer structures are typically used in high efficiency WOLEDs. However due to the complexity of the device structure comprising a stack of multiple layers of organic thin films, ten or more organic materials are usually required, and each of the layers in the stack has to be optimized to produce the desired electrical and optical functions such that collectively a WOLED of the highest possible efficiency can be achieved. Moreover, device degradation mechanisms are still unclear for most OLED systems, especially blue phosphorescent OLEDs. Such challenges require a deep understanding of the device operating principles and materials/device degradation mechanisms. This thesis will focus on achieving high-efficiency and color-stable all-phosphorescent WOLEDs through optimization of the device structures and material compositions. The operating principles and the degradation mechanisms specific to all-phosphorescent WOLED will be studied. First, we investigated a WOLED where a blue emitter was based on a doped mix-host system with the archetypal bis(4,6-difluorophenyl-pyridinato-N,C2) picolinate iridium(III), FIrpic, as the blue dopant. In forming the WOLED, the red and green components were incorporated in a single layer adjacent to the blue layer. The WOLED efficiency and color were optimized through variations of the mixed-host compositions to control the electron-hole recombination zone and the dopant concentrations of the green-red layers to achieve a balanced white emission. Second, a WOLED structure with two separate blue layers and an ultra-thin red and green co-doped layer was studied. Through a systematic investigation of the placement of the co-doped red and green layer between the blue layers and the material compositions of these layers, we were able to achieve high-efficiency WOLEDs with controllable white emission characteristics. We showed that we can use the ultra-thin co-doped layer and two blue emitting layers to manipulate exciton confinement to certain zones and energy transfer pathways between the various hosts and dopants. Third, a blue phosphorescent dopant tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (Ir(iprpmi)3) with a low ionization potential (HOMO 4.8 eV) and propensity for hole-trapping was studied in WOLEDs. In a bipolar host, 2,6-bis(3-(carbazol-9-yl)phenyl)-pyridine (DCzPPy), Ir(iprpmi)3 was found to trap holes at low concentrations but transport holes at higher concentrations. By adjusting the dopant concentration and thereby the location of the recombination zone, we were able to demonstrate blue and white OLEDs with external quantum efficiencies over 20%. The fabricated WOLEDs shows high color stability over a wide range of luminance. Moreover, the device lifetime has also been improved with Ir(iprpmi)3 as the emitter compared to FIrpic. Last, we analyzed OLED degradation using Laser Desorption Time-Of-Flight Mass Spectrometry (LDI-TOF-MS) technique. By carefully and systematically comparing the LDI-TOF patterns of electrically/optically stressed and controlled (unstressed) OLED devices, we were able to identify some prominent degradation byproducts and trace possible chemical pathways involving specific host and dopant materials.

Effective sulfur and energy recovery from hydrogen sulfide through incorporating an air-cathode fuel cell into chelated-iron process.

PubMed

Sun, Min; Song, Wei; Zhai, Lin-Feng; Cui, Yu-Zhi

2013-12-15

The chelated-iron process is among the most promising techniques for the hydrogen sulfide (H2S) removal due to its double advantage of waste minimization and resource recovery. However, this technology has encountered the problem of chelate degradation which made it difficult to ensure reliable and economical operation. This work aims to develop a novel fuel-cell-assisted chelated-iron process which employs an air-cathode fuel cell for the catalyst regeneration. By using such a process, sulfur and electricity were effectively recovered from H2S and the problem of chelate degradation was well controlled. Experiment on a synthetic sulfide solution showed the fuel-cell-assisted chelated-iron process could maintain high sulfur recovery efficiencies generally above 90.0%. The EDTA was preferable to NTA as the chelating agent for electricity generation, given the Coulombic efficiencies (CEs) of 17.8 ± 0.5% to 75.1 ± 0.5% for the EDTA-chelated process versus 9.6 ± 0.8% to 51.1 ± 2.7% for the NTA-chelated process in the pH range of 4.0-10.0. The Fe (III)/S(2-) ratio exhibited notable influence on the electricity generation, with the CEs improved by more than 25% as the Fe (III)/S(2-) molar ratio increased from 2.5:1 to 3.5:1. Application of this novel process in treating a H2S-containing biogas stream achieved 99% of H2S removal efficiency, 78% of sulfur recovery efficiency, and 78.6% of energy recovery efficiency, suggesting the fuel-cell-assisted chelated-iron process was effective to remove the H2S from gas streams with favorable sulfur and energy recovery efficiencies. Copyright © 2013 Elsevier B.V. All rights reserved.

Nonylphenol biodegradation characterizations and bacterial composition analysis of an effective consortium NP-M2.

PubMed

Bai, Naling; Abuduaini, Rexiding; Wang, Sheng; Zhang, Meinan; Zhu, Xufen; Zhao, Yuhua

2017-01-01

Nonylphenol (NP), ubiquitously detected as the degradation product of nonionic surfactants nonylphenol polyethoxylates, has been reported as an endocrine disrupter. However, most pure microorganisms can degrade only limited species of NP with low degradation efficiencies. To establish a microbial consortium that can effectively degrade different forms of NP, in this study, we isolated a facultative microbial consortium NP-M2 and characterized the biodegradation of NP by it. NP-M2 could degrade 75.61% and 89.75% of 1000 mg/L NP within 48 h and 8 days, respectively; an efficiency higher than that of any other consortium or pure microorganism reported so far. The addition of yeast extract promoted the biodegradation more significantly than that of glucose. Moreover, surface-active compounds secreted into the extracellular environment were hypothesized to promote high-efficiency metabolism of NP. The detoxification of NP by this consortium was determined. The degradation pathway was hypothesized to be initiated by oxidization of the benzene ring, followed by step-wise side-chain biodegradation. The bacterial composition of NP-M2 was determined using 16S rDNA library, and the consortium was found to mainly comprise members of the Sphingomonas, Pseudomonas, Alicycliphilus, and Acidovorax genera, with the former two accounting for 86.86% of the consortium. The high degradation efficiency of NP-M2 indicated that it could be a promising candidate for NP bioremediation in situ. Copyright © 2016 Elsevier Ltd. All rights reserved.

UV stabilization of wood by nano metal oxides dispersed in propylene glycol.

PubMed

Nair, Sreeja; Nagarajappa, Giridhar B; Pandey, Krishna K

2018-06-01

Nanoparticles of some of the metal oxides are known to have high UV protective efficiency. The UV filtering efficiency of nanoparticles invariably depends on their size and stability in the dispersion. In the present work, a stable dispersion of nanoparticles of three metal oxides, zinc oxide (ZnO), cerium oxide (CeO 2 ) and titanium dioxide (TiO 2 ), was prepared in propylene glycol (PG) using ultrasonication. The method is easy and useful as no additional surfactant or dispersant is needed. The particle size and its distribution was confirmed by Scanning Electron Microscopy and Dynamic Light Scattering. The stability of dispersion was assessed by UV-visible absorption spectroscopy. The UV stability of wood surfaces of Wrightia tinctoria coated with nanodispersions of ZnO, CeO 2 and TiO 2 was evaluated under laboratory conditions in an accelerated weathering tester. Changes in the colour and FTIR spectra of exposed specimens were measured periodically. Rapid colour darkening (yellowing) was observed in uncoated and PG coated specimens. In contrast, nanodispersion coated specimens prevented photo-yellowing considerably with significant reduction in colour changes examined by CIE L*, a*, b* and ΔE*. Increase in concentration of nanoparticles in the dispersion imparted higher resistance to UV induced degradation. However, increased concentration of nanoparticles reduced the transparency of the coating. FTIR analysis indicated rapid degradation of lignin in uncoated and PG coated specimens due to UV exposure. Coating of wood surfaces with nanodispersions restricted lignin degradation. The study also demonstrates the potential of propylene glycol as a dispersant for developing stable and efficient UV protective nanodispersions for wood coating. Copyright © 2018 Elsevier B.V. All rights reserved.

Tyrosine-phosphorylation of AAV2 vectors and its consequences on viral intracellular trafficking and transgene expression

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

Zhong Li; Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL; Genetics Institute, University of Florida College of Medicine, Gainesville, FL

2008-11-25

We have documented that epidermal growth factor receptor protein tyrosine kinase (EGFR-PTK) signaling negatively affects intracellular trafficking and transduction efficiency of recombinant adeno-associated virus 2 (AAV2) vectors. Specifically, inhibition of EGFR-PTK signaling leads to decreased ubiquitination of AAV2 capsid proteins, which in turn, facilitates viral nuclear transport by limiting proteasome-mediated degradation of AAV2 vectors. In the present studies, we observed that AAV capsids can indeed be phosphorylated at tyrosine residues by EGFR-PTK in in vitro phosphorylation assays and that phosphorylated AAV capsids retain their structural integrity. However, although phosphorylated AAV vectors enter cells as efficiently as their unphosphorylated counterparts, theirmore » transduction efficiency is significantly reduced. This reduction is not due to impaired viral second-strand DNA synthesis since transduction efficiency of both single-stranded AAV (ssAAV) and self-complementary AAV (scAAV) vectors is decreased by {approx} 68% and {approx} 74%, respectively. We also observed that intracellular trafficking of tyrosine-phosphorylated AAV vectors from cytoplasm to nucleus is significantly decreased, which results from ubiquitination of AAV capsids followed by proteasome-mediated degradation, although downstream consequences of capsid ubiquitination may also be affected by tyrosine-phosphorylation. These studies provide new insights into the role of tyrosine-phosphorylation of AAV capsids in various steps in the virus life cycle, which has implications in the optimal use of recombinant AAV vectors in human gene therapy.« less

Simulation study of GaAsP/Si tandem cells including the impact of threading dislocations on the luminescent coupling between the cells

NASA Astrophysics Data System (ADS)

Onno, Arthur; Harder, Nils-Peter; Oberbeck, Lars; Liu, Huiyun

2016-03-01

A model, derived from the detailed balance model from Shockley and Queisser, has been adapted to monolithically grown GaAsP/Si tandem dual junction solar cells. In this architecture, due to the difference of lattice parameters between the silicon bottom cell - acting as the substrate - and the GaAsP top cell, threading dislocations (TDs) arise at the IIIV/ Si interface and propagate in the top cell. These TDs act as non-radiative recombination centers, degrading the performances of the tandem cell. Our model takes into account the impact of TDs by integrating the NTT model developed by Yamaguchi et. al.. Two surface geometries have been investigated: flat and ideally textured. Finally the model considers the luminescent coupling (LC) between the cells due to reemitted photons from the top cell cascading to the bottom cell. Without dislocations, LC allows a greater flexibility in the cell design by rebalancing the currents between the two cells when the top cell presents a higher short-circuit current. However we show that, as the TD density (TDD) increases, nonradiative recombinations take over radiative recombinations in the top cell and the LC is quenched. As a result, nonoptimized tandem cells with higher short-circuit current in the top cell experience a very fast degradation of efficiency for TDDs over 104cm-2. On the other hand optimized cells with matching currents only experience a small efficiency drop for TDDs up to 105cm-2. High TDD cells therefore need to be current-matched for optimal performances as the flexibility due to LC is lost.

Microbial degradation of lignin: how a bulky recalcitrant polymer is efficiently recycled in nature and how we can take advantage of this.

PubMed

Ruiz-Dueñas, Francisco J; Martínez, Angel T

2009-03-01

Lignin is the second most abundant constituent of the cell wall of vascular plants, where it protects cellulose towards hydrolytic attack by saprophytic and pathogenic microbes. Its removal represents a key step for carbon recycling in land ecosystems, as well as a central issue for industrial utilization of plant biomass. The lignin polymer is highly recalcitrant towards chemical and biological degradation due to its molecular architecture, where different non-phenolic phenylpropanoid units form a complex three-dimensional network linked by a variety of ether and carbon-carbon bonds. Ligninolytic microbes have developed a unique strategy to handle lignin degradation based on unspecific one-electron oxidation of the benzenic rings in the different lignin substructures by extracellular haemperoxidases acting synergistically with peroxide-generating oxidases. These peroxidases poses two outstanding characteristics: (i) they have unusually high redox potential due to haem pocket architecture that enables oxidation of non-phenolic aromatic rings, and (ii) they are able to generate a protein oxidizer by electron transfer to the haem cofactor forming a catalytic tryptophanyl-free radical at the protein surface, where it can interact with the bulky lignin polymer. The structure-function information currently available is being used to build tailor-made peroxidases and other oxidoreductases as industrial biocatalysts. © 2009 The Authors. Journal compilation © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

Evaluation of the effect of organic pro-degradant concentration in polypropylene exposed to the natural ageing

NASA Astrophysics Data System (ADS)

Montagna, L. S.; Catto, A. L.; Rossini, K.; Forte, M. M. C.; Santana, R. M. C.

2014-05-01

The production and consumption of plastics in the last decade has recorded a remarkable increase in the scientific and industrial interest in environmentally degradable polymer (EDPs). Polymers wastes are deposited improperly, such as dumps, landfills, rivers and seas, causing a serious problem by the accumulation in the environment. The abiotic processes, like the photodegradation, are the most efficient occurring in the open environmental, where the polymers undergo degradation from the action of sunlight that result from direct exposure to solar radiation, however depend of the type of chemical ageing, which is the principal component of climatic ageing. The subject of this work is to study the influence of concentration of organic pro-degradant (1, 2 and 3 % w/w) in the polypropylene (PP) exposed in natural ageing. PP samples with and without the additive were processed in plates square form, obtained by thermal compression molding (TCM) using a press at 200°C under 2 tons for 5 min, and then were exposed at natural ageing during 120 days. The presence of organic additive influenced on PP degradability, this fact was assessed by changes in the thermal and morphology properties of the samples after 120 days of natural ageing. Scanning Electronic Microscopy (SEM) results of the morphological surface of the modified PP samples showed greater degradation photochemical oxidative when compared to neat PP, due to increase of rugosity and formation of microvoids. PP samples with different pro-degradant concentration under natural ageing presented a degree of crystallinity, obtained by Differential Scanning Calorimeter (DSC) increases in comparing the neat PP.

A Sensor-Based Method for Diagnostics of Machine Tool Linear Axes.

PubMed

Vogl, Gregory W; Weiss, Brian A; Donmez, M Alkan

2015-01-01

A linear axis is a vital subsystem of machine tools, which are vital systems within many manufacturing operations. When installed and operating within a manufacturing facility, a machine tool needs to stay in good condition for parts production. All machine tools degrade during operations, yet knowledge of that degradation is illusive; specifically, accurately detecting degradation of linear axes is a manual and time-consuming process. Thus, manufacturers need automated and efficient methods to diagnose the condition of their machine tool linear axes without disruptions to production. The Prognostics and Health Management for Smart Manufacturing Systems (PHM4SMS) project at the National Institute of Standards and Technology (NIST) developed a sensor-based method to quickly estimate the performance degradation of linear axes. The multi-sensor-based method uses data collected from a 'sensor box' to identify changes in linear and angular errors due to axis degradation; the sensor box contains inclinometers, accelerometers, and rate gyroscopes to capture this data. The sensors are expected to be cost effective with respect to savings in production losses and scrapped parts for a machine tool. Numerical simulations, based on sensor bandwidth and noise specifications, show that changes in straightness and angular errors could be known with acceptable test uncertainty ratios. If a sensor box resides on a machine tool and data is collected periodically, then the degradation of the linear axes can be determined and used for diagnostics and prognostics to help optimize maintenance, production schedules, and ultimately part quality.

Photocatalytic degradation of recalcitrant organic pollutants in water using a novel cylindrical multi-column photoreactor packed with TiO2-coated silica gel beads.

PubMed

Li, Dawei; Zhu, Qi; Han, Chengjie; Yang, Yingnan; Jiang, Weizhong; Zhang, Zhenya

2015-03-21

A novel cylindrical multi-column photocatalytic reactor (CMCPR) has been developed and successfully applied for the degradation of methyl orange (MO), amoxicillin (AMX) and 3-chlorophenol (3-CP) in water. Due to its higher adsorption capacity and simpler molecular structure, 3-CP compared with MO and AMX obtained the highest photodegradation (100%) and mineralization (78.1%) after 300-min photocatalytic reaction. Electrical energy consumption for photocatalytic degradation of MO, AMX and 3-CP using CMCPR was 5.79×10(4), 7.31×10(4) and 2.52×10(4) kW h m(-3) order(-1), respectively, which were less than one-thousand of those by reported photoreactors. The higher flow rate (15 mL min(-1)), lower initial concentration (5 mg L(-1)) and acidic condition (pH 3) were more favorable for the photocatalytic degradation of MO using CMCPR. Five repetitive operations of CMCPR achieved more than 97.0% photodegradation of MO in each cycle and gave a relative standard deviation of 0.72%. In comparison with reported slurry and thin-film photoreactors, CMCPR exhibited higher photocatalytic efficiency, lower energy consumption and better repetitive operation performance for the degradation of MO, AMX and 3-CP in water. The results demonstrated the feasibility of utilizing CMCPR for the degradation of recalcitrant organic pollutants in water. Copyright © 2014 Elsevier B.V. All rights reserved.

A Sensor-Based Method for Diagnostics of Machine Tool Linear Axes

PubMed Central

Vogl, Gregory W.; Weiss, Brian A.; Donmez, M. Alkan

2017-01-01

A linear axis is a vital subsystem of machine tools, which are vital systems within many manufacturing operations. When installed and operating within a manufacturing facility, a machine tool needs to stay in good condition for parts production. All machine tools degrade during operations, yet knowledge of that degradation is illusive; specifically, accurately detecting degradation of linear axes is a manual and time-consuming process. Thus, manufacturers need automated and efficient methods to diagnose the condition of their machine tool linear axes without disruptions to production. The Prognostics and Health Management for Smart Manufacturing Systems (PHM4SMS) project at the National Institute of Standards and Technology (NIST) developed a sensor-based method to quickly estimate the performance degradation of linear axes. The multi-sensor-based method uses data collected from a ‘sensor box’ to identify changes in linear and angular errors due to axis degradation; the sensor box contains inclinometers, accelerometers, and rate gyroscopes to capture this data. The sensors are expected to be cost effective with respect to savings in production losses and scrapped parts for a machine tool. Numerical simulations, based on sensor bandwidth and noise specifications, show that changes in straightness and angular errors could be known with acceptable test uncertainty ratios. If a sensor box resides on a machine tool and data is collected periodically, then the degradation of the linear axes can be determined and used for diagnostics and prognostics to help optimize maintenance, production schedules, and ultimately part quality. PMID:28691039

Phenol-degrading anode biofilm with high coulombic efficiency in graphite electrodes microbial fuel cell.

PubMed

Zhang, Dongdong; Li, Zhiling; Zhang, Chunfang; Zhou, Xue; Xiao, Zhixing; Awata, Takanori; Katayama, Arata

2017-03-01

A microbial fuel cell (MFC), with graphite electrodes as both the anode and cathode, was operated with a soil-free anaerobic consortium for phenol degradation. This phenol-degrading MFC showed high efficiency with a current density of 120 mA/m 2 and a coulombic efficiency of 22.7%, despite the lack of a platinum catalyst cathode and inoculation of sediment/soil. Removal of planktonic bacteria by renewing the anaerobic medium did not decrease the performance, suggesting that the phenol-degrading MFC was not maintained by the planktonic bacteria but by the microorganisms in the anode biofilm. Cyclic voltammetry analysis of the anode biofilm showed distinct oxidation and reduction peaks. Analysis of the microbial community structure of the anode biofilm and the planktonic bacteria based on 16S rRNA gene sequences suggested that Geobacter sp. was the phenol degrader in the anode biofilm and was responsible for current generation. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

An evaluation of electronic cigarette formulations and aerosols for harmful and potentially harmful constituents (HPHCs) typically derived from combustion.

PubMed

Wagner, Karl A; Flora, Jason W; Melvin, Matt S; Avery, Karen C; Ballentine, Regina M; Brown, Anthony P; McKinney, Willie J

2018-06-01

U.S. FDA draft guidance recommends reporting quantities of designated harmful and potentially harmful constituents (HPHCs) in e-cigarette e-liquids and aerosols. The HPHC list comprises potential matrix-related compounds, flavors, nicotine, tobacco-related impurities, leachables, thermal degradation products, and combustion-related compounds. E-cigarettes contain trace levels of many of these constituents due to tobacco-derived nicotine and thermal degradation. However, combustion-related HPHCs are not likely to be found due to the relatively low operating temperatures of most e-cigarettes. The purpose of this work was to use highly sensitive, selective, and validated analytical methods to determine if these combustion-related HPHCs (three aromatic amines, five volatile organic compounds, and the polycyclic aromatic hydrocarbon benzo[a]pyrene) are detectable in commercial refill e-liquids, reference e-cigarette e-liquids, and aerosols generated from rechargeable e-cigarettes with disposable cartridges (often referred to as "cig-a-likes"). In addition, the transfer efficiency of these constituents from e-liquid to aerosol was evaluated when these HPHCs were added to the e-liquids prior to aerosol formation. This work demonstrates that combustion-related HPHCs are not present at measurable levels in the commercial and reference e-liquids or e-cigarette aerosols tested. Additionally, when combustion-related HPHCs are added to the e-liquids, they transfer to the aerosol with transfer efficiencies ranging from 49% to 99%. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Adsorption-photodegradation of humic acid in water by using ZnO coupled TiO2/bamboo charcoal under visible light irradiation.

PubMed

Wang, Xuejiang; Wu, Zhen; Wang, Yin; Wang, Wei; Wang, Xin; Bu, Yunjie; Zhao, Jianfu

2013-11-15

ZnO coupled TiO2/bamboo charcoal (ZnO-TiO2/BC) was prepared using the sol-gel method combined with microwave irradiation. The ZnO-TiO2/BC and TiO2/BC were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption (BET), and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). The ZnO dopant promoted the transformation of anatase TiO2 to rutile phase, and a significant red shift of absorption edge was brought out due to the interfacial coupling effect between ZnO and TiO2 particles. The BET specific surface area and total pore volume decreased with ZnO doping, indicating that some micropores were blocked. SEM studies indicated that ZnO was almost uniformly deposited on the surface of the ZnO-TiO2/BC. The adsorption and photocatalytic degradation experiments showed that the photo-degrade efficiency for Zno-TiO2/BC was higher than that of TiO2/BC, and for both composites, the removal efficiency of HA increased as pH decreased from 10.0 to 2.0. The degradation of HA by ZnO-TiO2/BC and TiO2/BC fitted well with the Langmuir-Hinshelwood kinetics model, and HA degradation was achieved through a synergistic mechanism of adsorption and photocatalysis. ZnO-TiO2/BC could be used as an effective and alternative photocatalyst for the treatment of water contaminated by organic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

Fenton-like Degradation of Phenol Catalyzed by a Series of Fe-Containing Mixed Oxides Systems

NASA Astrophysics Data System (ADS)

Alhmoud, T. T.; Mahmoud, S. S.; Hammoudeh, A. Y.

2018-02-01

In our attempts to develop a solid catalyst to degrade organic pollutants in wastewater via the Fenton-like reaction, six Fe-containing mixed oxide systems were prepared by means of the sol-gel auto-combustion method to have the following stoichiometries: CuFe1.2O2.8, BaFe7.2O11.8, BaFe7.2Cu2O13.8, BaFe5.4V3O16.6, BaFe4.8Cu2V3O17.7 and Ag2Fe5.4V3O16.6. The prepared systems were thermally treated at 550°C, 650°C, 800°C and 1100°C, and then characterized by XRD to identify the present phases. The systems were tested with respect to their catalytic efficiency in the degradation of phenol (200 ppm) in water where CuFe1.2O2.8 was found to be the most reactive one (80% removal in 60 min). It showed thereby first-order kinetics and an enhanced behavior under irradiation with a 30-W LED light source. The positive role of irradiation was most obvious in the case of Ag2Fe5.4V3O16.6 in which almost complete conversion was achieved in 120 min compared to only 45% in the same period but without irradiation. However, increasing the temperature at which thermal treatment is performed was found to suppress the catalytic activity of the system. Due to their high efficiency and rather low leaching rates of constituents, CuFe1.2O2.8 or Ag2Fe5.4V3O16.6 seem to be very promising in the Fenton-like degradation of organic pollutants.

Assessment of potential positive effects of nZVI surface modification and concentration levels on TCE dechlorination in the presence of competing strong oxidants, using an experimental design.

PubMed

Kaifas, Delphine; Malleret, Laure; Kumar, Naresh; Fétimi, Wafa; Claeys-Bruno, Magalie; Sergent, Michelle; Doumenq, Pierre

2014-05-15

Nanoscale zero-valent iron (nZVI) particles are efficient for the remediation of aquifers polluted by trichloroethylene (TCE). But for on-site applications, their reactivity can be affected by the presence of common inorganic co-pollutants, which are equally reduced by nZVI particles. The aim of this study was to assess the potential positive effects of nZVI surface modification and concentration level on TCE removal in the concomitant presence of two strong oxidants, i.e., Cr(VI) and NO3(-). A design of experiments, testing four factors (i.e. nZVI concentration, nZVI surface modification, Cr(VI) concentration and NO3(-) concentration), was used to select the best trials for the identification of the main effects of the factors and of the factors interactions. The effects of these factors were studied by measuring the following responses: TCE removal rates at different times, degradation kinetic rates, and the transformation products formed. As expected, TCE degradation was delayed or inhibited in most of the experiments, due to the presence of inorganics. The negative effects of co-pollutants can be palliated by combining surface modification with a slight increase in nZVI concentration. Encouragingly, complete TCE removal was achieved for some given experimental conditions. Noteworthily, nZVI surface modification was found to promote the efficient degradation of TCE. When degradation occurred, TCE was mainly transformed into innocuous non-chlorinated transformation products, while hazardous chlorinated transformation products accounted for a small percentage of the mass-balance. Copyright © 2014 Elsevier B.V. All rights reserved.

Distribution of electrical energy consumption for the efficient degradation control of THMs mixture in sonophotolytic process.

PubMed

Park, Beomguk; Cho, Eunju; Son, Younggyu; Khim, Jeehyeong

2014-11-01

Sonophotolytic degradation of THMs mixture with different electrical energy ratio was carried out for efficient design of process. The total consumed electrical energy was fixed around 50W, and five different energy conditions were applied. The maximum degradation rate showed in conditions of US:UV=1:3 and US:UV=0:4. This is because the photolytic degradation of bromate compounds is dominant degradation mechanism for THMs removal. However, the fastest degradation of total organic carbon was observed in a condition of US:UV=1:3. Because hydrogen peroxide generated by sonication was effectively dissociated to hydroxyl radicals by ultraviolet, the concentration of hydroxyl radical was maintained high. This mechanism provided additional degradation of organics. This result was supported by comparison between the concentration of hydrogen peroxide sole and combined process. Consequently, the optimal energy ratio was US:UV=1:3 for degradation of THMs in sonophotolytic process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO2.

PubMed

Ozmen, Murat; Güngördü, Abbas; Erdemoglu, Sema; Ozmen, Nesrin; Asilturk, Meltem

2015-08-01

The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO2. Undoped and Mn-doped TiO2 nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO2 was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO2 nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO2 increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2-4h of degradation. However, biochemical assays showed that both Mn-doped TiO2 and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn-doped TiO2 should be considered due to nanomaterial applications and for spilled nanoparticles in an aquatic ecosystem. Also, the risk of nanoparticles should be considered using indicator reference biochemical markers to verify the environmental health impacts. Copyright © 2015 Elsevier B.V. All rights reserved.

Leachate from Municipal Waste Landfill and Its Natural Degradation-A Case Study of Zubří, Zlín Region.

PubMed

Václavík, Vojtěch; Ondrašiková, Ivana; Dvorský, Tomáš; Černochová, Kateřina

2016-09-01

This work deals with the natural degradation of leachate from an old reclaimed landfill by means of a biological pond. Hamra is a municipal waste landfill with a limited formation of leachate, which has already been reclaimed. Leachate in this location is disposed of using natural biogeochemical method, and it is subsequently discharged into a surface stream. The main issue dealt with here is the long-term effectiveness of natural degradation of leachate and the limits of its use. The solutions of these fundamental questions took advantage of a database of analytical assessments collected during a long-term monitoring of the landfill site. The primary degradation trends and the long-term development have been revealed and described on the basis of these assessments. The main benefit of the biological pond is the dilution of the dominant contaminants, especially of inorganic character. In the case of ammonium ions, they show nitrification caused by their transition from the reduction into oxidizing environment. From a long term point of view, the disadvantage of natural degradation of leachate can be seen in the gradual reduction in efficiency due to the concentration of the substances or an undesired growth of water plants, which can be successfully eliminated, for example, by means of targeted aeration and by maintaining vegetation in the pond and its surroundings. The biological potential of the locality is very favorable and, despite its anthropogenic load, it creates a location with suitable living conditions for many water animals and plants. That is why it can be concluded that the efficiency of the natural biochemical cleaning elements can be considered as sufficient, taking into account the nature of the deposited waste, the quantity and quality of leachate, as well as the climate character of the locality.

Humidity versus photo-stability of metal halide perovskite films in a polymer matrix.

PubMed

Manshor, Nurul Ain; Wali, Qamar; Wong, Ka Kan; Muzakir, Saifful Kamaluddin; Fakharuddin, Azhar; Schmidt-Mende, Lukas; Jose, Rajan

2016-08-21

Despite the high efficiency of over 21% reported for emerging thin film perovskite solar cells, one of the key issues prior to their commercial deployment is to attain their long term stability under ambient and outdoor conditions. The instability in perovskite is widely conceived to be humidity induced due to the water solubility of its initial precursors, which leads to decomposition of the perovskite crystal structure; however, we note that humidity alone is not the major degradation factor and it is rather the photon dose in combination with humidity exposure that triggers the instability. In our experiment, which is designed to decouple the effect of humidity and light on perovskite degradation, we investigate the shelf-lifetime of CH3NH3PbI3 films in the dark and under illumination under high humidity conditions (Rel. H. > 70%). We note minor degradation in perovskite films stored in a humid dark environment whereas upon exposure to light, the films undergo drastic degradation, primarily owing to the reactive TiO2/perovskite interface and also the surface defects of TiO2. To enhance its air-stability, we incorporate CH3NH3PbI3 perovskite in a polymer (poly-vinylpyrrolidone, PVP) matrix which retained its optical and structural characteristics in the dark for ∼2000 h and ∼800 h in room light soaking, significantly higher than a pristine perovskite film, which degraded completely in 600 h in the dark and in less than 100 h when exposed to light. We attribute the superior stability of PVP incorporated perovskite films to the improved structural stability of CH3NH3PbI3 and also to the improved TiO2/perovskite interface upon incorporating a polymer matrix. Charge injection from the polymer embedded perovskite films has also been confirmed by fabricating solar cells using them, thereby providing a promising future research pathway for stable and efficient perovskite solar cells.

A Highly Efficient Xylan-Utilization System in Aspergillus niger An76: A Functional-Proteomics Study.

PubMed

Gong, Weili; Dai, Lin; Zhang, Huaiqiang; Zhang, Lili; Wang, Lushan

2018-01-01

Xylan constituted with β-1,4-D-xylose linked backbone and diverse substituted side-chains is the most abundant hemicellulose component of biomass, which can be completely and rapidly degraded into fermentable sugars by Aspergillus niger . This is of great value for obtaining renewable biofuels and biochemicals. To clarify the underlying mechanisms associated with highly efficient xylan degradation, assimilation, and metabolism by A. niger , we utilized functional proteomics to analyze the secreted proteins, sugar transporters, and intracellular proteins of A. niger An76 grown on xylan-based substrates. Results demonstrated that the complete xylanolytic enzyme system required for xylan degradation and composed of diverse isozymes was secreted in a sequential order. Xylan-backbone-degrading enzymes were preferentially induced by xylose or other soluble sugars, which efficiently produced large amounts of xylooligosaccharides (XOS) and xylose; however, XOS was more efficient than xylose in triggering the expression of the key transcription activator XlnR, resulting in higher xylanase activity and shortening xylanase-production time. Moreover, the substituted XOS was responsible for improving the abundance of side-chain-degrading enzymes, specific transporters, and key reductases and dehydrogenases in the pentose catabolic pathway. Our findings indicated that industries might be able to improve the species and concentrations of xylan-degrading enzymes and shorten fermentation time by adding abundant intermediate products of natural xylan (XOS) to cultures of filamentous fungi.

A Highly Efficient Xylan-Utilization System in Aspergillus niger An76: A Functional-Proteomics Study

PubMed Central

Gong, Weili; Dai, Lin; Zhang, Huaiqiang; Zhang, Lili; Wang, Lushan

2018-01-01

Xylan constituted with β-1,4-D-xylose linked backbone and diverse substituted side-chains is the most abundant hemicellulose component of biomass, which can be completely and rapidly degraded into fermentable sugars by Aspergillus niger. This is of great value for obtaining renewable biofuels and biochemicals. To clarify the underlying mechanisms associated with highly efficient xylan degradation, assimilation, and metabolism by A. niger, we utilized functional proteomics to analyze the secreted proteins, sugar transporters, and intracellular proteins of A. niger An76 grown on xylan-based substrates. Results demonstrated that the complete xylanolytic enzyme system required for xylan degradation and composed of diverse isozymes was secreted in a sequential order. Xylan-backbone-degrading enzymes were preferentially induced by xylose or other soluble sugars, which efficiently produced large amounts of xylooligosaccharides (XOS) and xylose; however, XOS was more efficient than xylose in triggering the expression of the key transcription activator XlnR, resulting in higher xylanase activity and shortening xylanase-production time. Moreover, the substituted XOS was responsible for improving the abundance of side-chain-degrading enzymes, specific transporters, and key reductases and dehydrogenases in the pentose catabolic pathway. Our findings indicated that industries might be able to improve the species and concentrations of xylan-degrading enzymes and shorten fermentation time by adding abundant intermediate products of natural xylan (XOS) to cultures of filamentous fungi. PMID:29623069

Degradation of anti-inflammatory drugs in municipal wastewater by heterogeneous photocatalysis and electro-Fenton process.

PubMed

Villanueva-Rodríguez, Minerva; Bello-Mendoza, Ricardo; Hernández-Ramírez, Aracely; Ruiz-Ruiz, Edgar J

2018-03-01

Non-steroidal anti-inflammatory drugs (NSAID) are compounds frequently found in municipal wastewater and their degradation by conventional wastewater treatment plants (WWTP) is generally incomplete. This study compared the efficiency of two advanced oxidation processes (AOP), namely heterogeneous photocatalysis (HP) and electro-Fenton (EF), in the degradation of a mixture of common NSAID (diclofenac, ibuprofen and naproxen) dissolved in either deionized water or effluent from a WWTP. Both processes were effective in degrading the NSAID mixture and the trend of degradation was as follows, diclofenac > naproxen > ibuprofen. EF with a current density of 40 mA cm -2 and 0.3 mmol Fe 2+  L -1 was the most efficient process to mineralize the organic compounds, achieving up to 92% TOC removal in deionized water and 90% in the WWTP effluent after 3 h of reaction. HP with 1.4 g TiO 2  L -1 at pH 7 under sunlight, produced 85% TOC removal in deionized water and 39% in WWTP effluent also after 3 h treatment. The lower TOC removal efficiency shown by HP with the WWTP effluent was attributed mainly to the scavenging of reactive species by background organic matter in the wastewater. On the contrary, inorganic ions in the wastewater may produce oxidazing species during the EF process, which contributes to a higher degradation efficiency. EF is a promising option for the treatment of anti-inflammatory pharmaceuticals in municipal WWTP at competitive electrical energy efficiencies.

Improving the catalytic effect of peroxodisulfate and peroxodiphosphate electrochemically generated at diamond electrode by activation with light irradiation.

PubMed

de Araújo, Danyelle Medeiros; Sáez, Cristina; Cañizares, Pablo; Rodrigo, Manuel Andrés; Martínez-Huitle, Carlos A

2018-05-21

Boron doped diamond (BDD) anode has been used to oxidatively remove Rhodamine B (RhB), as persistent organic pollutant, from synthetic wastewater by electrolysis, photoelectrolysis and chemical oxidation containing sulfate and phosphate as supporting electrolytes. RhB is effectively oxidized by electrolysis and by chemical oxidation with the oxidants separately produced by electrolyzing sulfate or phosphate solutions (peroxodisulfate and peroxodiphosphate, respectively). The results showed that light irradiation improved the electrolysis of RhB due to the activation of oxidants under irradiation at high current densities. Meanwhile, the efficiency of the chemical oxidation approach by ex situ electrochemical production of oxidants was not efficient to degrade RhB. Copyright © 2018 Elsevier Ltd. All rights reserved.

Degradation of organic dyes by a new heterogeneous Fenton reagent - Fe2GeS4 nanoparticle.

PubMed

Shi, Xiaoguo; Tian, Ang; You, Junhua; Yang, He; Wang, Yuzheng; Xue, Xiangxin

2018-07-05

The heterogeneous Fenton system has become the hotspot in the decontamination field due to its effective degradation performance with a wide pH range. Based on the unstable chemical properties of pyrite, in this article, Fe 2 GeS 4 nanoparticles with better thermodynamic stability were prepared by vacuum sintering and high energy ball milling and its potential as Fenton reagent was investigated for the first time. Three determinants of the heterogeneous Fenton system including the iron source, hydrogen peroxide, pH and the degradation mechanism were investigated. The catalyst dosage of 0.3 g/L, initial H 2 O 2 concentration in the Fenton system of 50 m mol/L and pH of 7 were chosen as the best operational conditions. An almost complete degradation was achieved within 5 min for methylene blue and rhodamine b while 10 min for methyl orange. The total organic carbon removal efficiencies of Fe 2 GeS 4 heterogeneous Fenton system for methylene blue, methyl orange and rhodamine b in 10 min were 56.3%, 66.2% and 74.2%, respectively. It's found that the degradation ability could be attributed to a heterogeneous catalysis occurring at the Fe 2 GeS 4 surface together with a homogeneous catalysis in the aqueous phase by the dissolved iron ions. Copyright © 2018 Elsevier B.V. All rights reserved.

Insight into Enzymatic Degradation of Corn, Wheat, and Soybean Cell Wall Cellulose Using Quantitative Secretome Analysis of Aspergillus fumigatus.

PubMed

Sharma Ghimire, Prakriti; Ouyang, Haomiao; Wang, Qian; Luo, Yuanming; Shi, Bo; Yang, Jinghua; Lü, Yang; Jin, Cheng

2016-12-02

Lignocelluloses contained in animal forage cannot be digested by pigs or poultry with 100% efficiency. On contrary, Aspergillus fumigatus, a saprophytic filamentous fungus, is known to harbor 263 glycoside hydrolase encoding genes, suggesting that A. fumigatus is an efficient lignocellulose degrader. Hence the present study uses corn, wheat, or soybean as a sole carbon source to culture A. fumigatus under animal physiological condition to understand how cellulolytic enzymes work together to achieve an efficient degradation of lignocellulose. Our results showed that A. fumigatus produced different sets of enzymes to degrade lignocelluloses derived from corn, wheat, or soybean cell wall. In addition, the cellulolytic enzymes produced by A. fumigatus were stable under acidic condition or at higher temperatures. Using isobaric tags for a relative and absolute quantification (iTRAQ) approach, a total of ∼600 extracellular proteins were identified and quantified, in which ∼50 proteins were involved in lignocellulolysis, including cellulases, hemicellulases, lignin-degrading enzymes, and some hypothetical proteins. Data are available via ProteomeXchange with identifier PXD004670. On the basis of quantitative iTRAQ results, 14 genes were selected for further confirmation by RT-PCR. Taken together, our results indicated that the expression and regulation of lignocellulolytic proteins in the secretome of A. fumigatus were dependent on both nature and complexity of cellulose, thus suggesting that a different enzyme system is required for degradation of different lignocelluloses derived from plant cells. Although A. fumigatus is a pathogenic fungus and cannot be directly used as an enzyme source, as an efficient lignocellulose degrader its strategy to synergistically degrade various lignocelluloses with different enzymes can be used to design enzyme combination for optimal digestion and absorption of corn, wheat, or soybean that are used as forage of pig and poultry.

Chlorpyrifos degradation in a biomixture of biobed at different maturity stages.

PubMed

Tortella, G R; Rubilar, O; Castillo, M d P; Cea, M; Mella-Herrera, R; Diez, M C

2012-06-01

The biomixture is a principal element controlling the degradation efficacy of the biobed. The maturity of the biomixture used in the biobed affects its overall performance of the biobed, but this is not well studied yet. The aim of this research was to evaluate the effect of using a typical composition of Swedish biomixture at different maturity stages on the degradation of chlorpyrifos. Tests were made using biomixture at three maturity stages: 0 d (BC0), 15 d (BC15) and 30 d (BC30); chlorpyrifos was added to the biobeds at final concentration of 200, 320 and 480 mg kg(-1). Chlorpyrifos degradation in the biomixture was monitored over time. Formation of TCP (3,5,6-trichloro-2-pyrinidol) was also quantified, and hydrolytic and phenoloxidase activities measured. The biomixture efficiently degraded chlorpyrifos (degradation efficiency >50%) in all the evaluated maturity stages. However, chlorpyrifos degradation decreased with increasing concentrations of the pesticide. TCP formation occurred in all biomixtures, but a major accumulation was observed in BC30. Significant differences were found in both phenoloxidase and hydrolytic activities in the three maturity stages of biomixture evaluated. Also, these two biological activities were affected by the increase in pesticide concentration. In conclusion, our results demonstrated that chlorpyrifos can be degraded efficiently in all the evaluated maturity stages. Copyright © 2012 Elsevier Ltd. All rights reserved.

Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community

PubMed Central

Lezcano, María Ángeles; Morón-López, Jesús; Agha, Ramsy; López-Heras, Isabel; Nozal, Leonor; Quesada, Antonio; El-Shehawy, Rehab

2016-01-01

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlrA gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr+ and mlr− bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains (Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection (Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr+ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr− strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non-mlr microcystin degradation pathways. Considering the abundance of the mlr− bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non-mlr degradation pathways deserves special attention. PMID:27827872

High Efficient Visible-Light Photocatalytic Performance of Cu/ZnO/rGO Nanocomposite for Decomposing of Aqueous Ammonia and Treatment of Domestic Wastewater.

PubMed

He, Shiying; Hou, Pengfu; Petropoulos, Evangelos; Feng, Yanfang; Yu, Yingliang; Xue, Lihong; Yang, Linzhang

2018-01-01

Photocatalytic removal of ammonium-nitrogen ( NH 4 + -N) from water using solar energy is an approach of high interest and applicability due to the convenience in application. ZnO has a great potential in photocatalytic decomposition of NH 4 + -N and conversion of this nutrient to under visible light irradiations. However the applicability of pristine ZnO though is limited due to its reduced capacity to utilize light from natural light. Herein, we report a two-step ZnO-modified strategy (Cu-doped ZnO nanoparticles, immobilized on reduced graphene oxide (rGO) sheets) for the promotion of photocatalytic degradation of NH 4 + -N under visible light. UV-Vis spectra showed that the Cu/ZnO/rGO can be highly efficient in the utilization of photons from the visible region. Hence, Cu/ZnO/rGO managed to demonstrate adequate photocatalytic activity and effective NH 4 + -N removal from water under visible light compared to single ZnO. Specifically, up to 83.1% of NH 4 + -N (initial concentration 50 mg·L -1 , catalyst dosage 2 g·L -1 , pH 10) was removed within 2 h retention time under Xe lamp irradiation. From the catalysis, the major by-product was N 2 . The high ammonia degradation efficiency from the ZnO/Cu/rGO is attributed to the improvement of the reactive oxygen species (ROSs) production efficiency and the further activation of the interfacial catalytic sites. This study also demonstrated that such nanocomposite is a recyclable agent. Its NH 4 + -N removal capacity remained effective even after five batch cycles. In addition, Cu/ZnO/rGO was applied to treat real domestic wastewater, and it was found that chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies can reach 84.3, 80.7, and 90.3%, respectively. Thus, Cu/ZnO/rGO in the presence of solar light can be a promising photocatalyst in the field of wastewater treatment.

Soil washing in combination with homogeneous Fenton-like oxidation for the removal of 2,4,4'-trichlorodiphenyl from soil contaminated with capacitor oil.

PubMed

Ma, Xiao-Hong; Zhao, Ling; Lin, Zhi-Rong; Dong, Yuan-Hua

2016-04-01

Detoxification by chemical oxidation of polychlorinated biphenyls (PCBs) in contaminated soils is very difficult and inefficient because PCBs typically associate with the solid phase or exist as non-aqueous-phase liquids due to their low solubility and slow desorption rates, and thus, they are difficult to remove from soils by using traditional, water-based elution techniques. Surfactant can enhance washing efficiency of PCBs from contaminated soils. This study used Brij 58, Brij 30, Tween 80, and 2-hydroxypropyl-β-cyclodextrin (HPCD) to solubilize 2,4,4'-trichlorodiphenyl (PCB28) from soil contaminated with capacitor oil into solution. The feasibility of PCB28 oxidation in soil washing wastewater through a Fe(3+)-catalyzed Fenton-like reaction was subsequently examined. Washing with 10 g L(-1) Brij 58 solution showed the highest extraction efficiency (up to 61.5 %) compared with that of the three other surfactants. The total concentration of PCB28 in contaminated soil at 25 °C after 48-h extraction was 286 mg L(-1). In contrast to conditions in which no washing agent was added, addition of the four washing agents decreased the efficiency of PCB28 degradation by the Fenton-like reaction, with the decrease due to addition of 10 g L(-1) Brij 58 solution being the smallest. The optimal concentration of H2O2 for preventing its useless decomposition was found to be 50 mM. The efficiency of PCB28 removal was lower when the initial concentration of PCB28 treated in the Fenton-like reaction was higher. The degradation efficiencies of PCB28 at initial concentrations of 0.1, 10, and 176 mg L(-1) in 10 g L(-1) Brij 58 solution at 25 °C and pH 3.0 and 9 h of reaction using 50 mM H2O2 were 64.1, 42.0, and 34.6 %, respectively. This result indicates that soil washing combined with Fenton-like oxidation may be a practical approach for the remediation of PCB-contaminated soil.

Fenton-like reaction: a possible way to efficiently remove illicit drugs and pharmaceuticals from wastewater.

PubMed

Mackuľak, Tomáš; Mosný, Michal; Grabic, Roman; Golovko, Oksana; Koba, Olga; Birošová, Lucia

2015-03-01

We analyzed 13 psychoactive pharmaceuticals, illicit drugs and their metabolites in wastewater treatment plant influent and effluent and the possibility of their degradation by biological and chemical processes. Tramadol (413-853 ng/L) and methamphetamine (460-682 ng/L) were the most concentrated compounds in the wastewater in winter and summer, respectively. A significant decrease in the concentration of tramadol in wastewater was measured during the summer. The lowest efficiency was observed for tramadol, venlafaxine, citalopram and oxazepam (∼ 10%) and the highest efficiency was observed for amphetamine and THC-COOH (∼ 80%). The efficiency of compound degradation via the Fenton reaction, a modified Fenton reaction and different degradation (by algae, wood-rotting fungi and enzymes at influent versus effluent) was determined. The Fenton reaction and its modification were efficient at eliminating these substances in comparison with the tested biological processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Structure–efficiency relationships of cyclodextrin scavengers in the hydrolytic degradation of organophosphorus compounds

PubMed Central

Letort, Sophie; Bosco, Michaël; Cornelio, Benedetta; Brégier, Frédérique; Daulon, Sébastien; Gouhier, Géraldine

2017-01-01

New derivatives of cyclodextrins were prepared in order to determine the relative importance of the structural key elements involved in the degradation of organophosphorus nerve agents. To avoid a competitive inclusion between the organophosphorus substrate and the iodosobenzoate group, responsible for its degradation, the latter group had to be covalently bound to the cyclodextrin scaffold. Although the presence of the α nucleophile iodosobenzoate was a determinant in the hydrolysis process, an imidazole group was added to get a synergistic effect towards the degradation of the agents. The degradation efficiency was found to be dependent on the relative position of the heterocycle towards the reactive group as well as on the nature of the organophosphorus derivative. PMID:28382180

Structure-efficiency relationships of cyclodextrin scavengers in the hydrolytic degradation of organophosphorus compounds.

PubMed

Letort, Sophie; Bosco, Michaël; Cornelio, Benedetta; Brégier, Frédérique; Daulon, Sébastien; Gouhier, Géraldine; Estour, François

2017-01-01

New derivatives of cyclodextrins were prepared in order to determine the relative importance of the structural key elements involved in the degradation of organophosphorus nerve agents. To avoid a competitive inclusion between the organophosphorus substrate and the iodosobenzoate group, responsible for its degradation, the latter group had to be covalently bound to the cyclodextrin scaffold. Although the presence of the α nucleophile iodosobenzoate was a determinant in the hydrolysis process, an imidazole group was added to get a synergistic effect towards the degradation of the agents. The degradation efficiency was found to be dependent on the relative position of the heterocycle towards the reactive group as well as on the nature of the organophosphorus derivative.

Substrate degradation by the proteasome: a single-molecule kinetic analysis

PubMed Central

Lu, Ying; Lee, Byung-hoon; King, Randall W; Finley, Daniel; Kirschner, Marc W

2015-01-01

To address how the configuration of conjugated ubiquitins determines the recognition of substrates by the proteasome, we analyzed the degradation kinetics of substrates with chemically defined ubiquitin configurations. Contrary to the view that a tetraubiquitin chain is the minimal signal for efficient degradation, we find that distributing the ubiquitins as diubiquitin chains provides a more efficient signal. To understand how the proteasome actually discriminates among ubiquitin configurations, we developed single-molecule assays that distinguished intermediate steps of degradation kinetically. The level of ubiquitin on a substrate drives proteasome-substrate interaction, whereas the chain structure of ubiquitin affects translocation into the axial channel on the proteasome. Together these two features largely determine the susceptibility of substrates for proteasomal degradation. PMID:25859050

Efficient transformation of DDT by peroxymonosulfate activated with cobalt in aqueous systems: Kinetics, products, and reactive species identification.

PubMed

Qin, Wenxiu; Fang, Guodong; Wang, Yujun; Wu, Tongliang; Zhu, Changyin; Zhou, Dongmei

2016-04-01

Recently, sulfate radical ( [Formula: see text] ) based-advanced oxidation technologies (AOTs) have been attracted great attention in the remediation of contaminated soil and groundwater. In the present study, Co(2+) ions activated peroxymonosulfate (PMS) system was used to degrade 1, 1, 1-trichloro-2, 2'bis(p-chlorophenyl) ethane (DDT) in aqueous solutions. It was found that DDT was efficiently degraded in the PMS/Co(II) solutions within several hours, and the degradation efficiency of DDT was dependent on the concentrations of PMS and Co(II), and the optimum molar ratio of PMS and Co(II) was 50:1. The degradation kinetics of DDT were well described with pseudo-first-order equations over a range of temperature (10-40 °C), and the activation energy that was calculated with Arrhenius equation was 72.3 ± 2.6 kJ/mol. Electron paramagnetic resonance (EPR) and GC-MS techniques were applied to identify the intermediates and reactive species for DDT degradation. The results indicated that [Formula: see text] and OH were the main reactive species accounting for DDT degradation. Dichlorobenzophenone, 4-chlorobenzoic acid and benzylalcohol were the dominant intermediates for DDT degradation, and the likely degradation pathway of DDT was proposed on the basis of these identified products. Increasing pH inhibited the formation of [Formula: see text] and OH, and thus decreased the catalytic degradation of DDT. Cl(-) ion was found to significantly inhibit, while [Formula: see text] and dissolved oxygen had limited effects on DDT degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adsorption Assisted Photocatalytic Removal of Methyl Orange by MgAl2O4-Sb2S3 Composite Material.

PubMed

Muneeb, Muhammad; Ismail, Bushra; Fazal, Tanzeela; Khan, Abdur Rehman; Afzia, Mehwish

2016-01-01

The current article is about the water treatment in which colored water contaminated by methyl orange has been used for adsorption assisted photocatalysis. Coupling of photocatalysis with the traditional water treatment processes has been in practice since last couple of years for the improvement of degradation efficiencies, for example, photocatalysis coupled with ultrafilteration, adsorption, flocculation, biological methods, photolysis, membrane distillation, etc. Among all these coupling approaches, adsorption assisted photocatalysis being a very simple and highly efficient approach is suffering from few drawbacks on the account of high cost, low stability and surface area of the adsorbent support. The present study is a contribution towards improvement in this coupling approach. A low cost, highly stable spinel magnesium aluminate (MgAl2O4) material synthesized at nanoscale is used for composite formation with antimony sulphide (Sb2S3) material having high absorption coefficient in the visible light of solar spectrum. A review of recent patents shows that the field of photoctalysis is dominated by the traditional TiO2 catalyst. The modification of TiO2 by either composite formation or by doping is the main focus. Coprecipitation method is used for the synthesis of spinel in which the desired precursors in the respective molar ratios were mixed and annealing of the resulting precipitates was carried out at 800oC for 8 h. Sb2S3 was synthesized by the hydrothermal method in which the required molar solution of precursors was mixed with urea solution and the whole mixture was maintained at 105oC for 6 hrs in a Teflon lined autoclave. The resulting suspension was then annealed at 37oC for 3 hours. The composite of Sb2S3 and MgAl2O4 has been synthesized by mixing both the materials in 1:1 and heat treated in an oven at a temperature of 200oC. Peaks in X-ray diffraction pattern correspond to both the Sb2S3 and spinel phase. All the peaks corresponding to the Sb2S3 and spinel phase were found to be shifted to higher d-spacing values. This indicates the expansion of unit cells of the Sb2S3 and MgAl2O4 phases. Thermal studies show that only 3% weight loss is observed at a temperature of 200-1000oC which may be due to the loss of surface water from the sample. Surface area, pore volume and pore size obtained from N2 adsorption were 143m2/g, 0.21cc/g and 23.26Å, respectively. The removal efficiency of 0.1g catalyst for methyl orange solution of 5mg/L concentration after reaction in dark conditions for the time of one hour was calculated to be 24% owing to the adsorption. The visible light degradation efficiency of the 0.1g catalyst for 1, 5, 19, 25 and 50 mg/L concentrations of MO solutions were 97, 93, 75, 72 and 62% respectively. The dosage of the catalyst was found to have a direct relationship with the degradation efficiency. Lower pH was found suitable for the degradation owing to better interaction of catalyst surface and the adsorbed dye. Percent degradation increased with the increase in the time and temperature of reaction. The degradation kinetics followed pseudo first order rate equation; the calculated value of rate constant was 0.0102 min-1. The mechanism involves the excitation of electrons in the valence band of Sb2S3 to the conduction band by the absorption of visible and UV light. The electrons and holes participate in the surface reactions resulting in the formation of superoxide and hydroxyl radicals which degrade the targeted polluted. Lower concentration of MO solutions, acidic pH, higher catalyst dosage and greater reaction times were found suitable for the degradation efficiency.

Study of the Staebler-Wronski degradation effect in a-Si:H based p-i-n solar cell

NASA Technical Reports Server (NTRS)

Naseem, H. A.; Brown, W. D.; Ang, S. S.

1993-01-01

Conversion of solar energy into electricity using environmentally safe and clean photovoltaic methods to supplement the ever increasing energy needs has been a cherished goal of many scientists and engineers around the world. Photovoltaic solar cells on the other hand, have been the power source for satellites ever since their introduction in the early sixties. For widespread terrestrial applications, however, the cost of photovoltaic systems must be reduced considerably. Much progress has been made in the recent past towards developing economically viable terrestrial systems, and the future looks highly promising. Thin film solar cells offer cost reductions mainly from their low processing cost, low material cost, and choice of low cost substrates. These are also very attractive for space applications because of their high power densities (power produced per kilogram of solar cell pay load) and high radiation resistance. Amorphous silicon based solar cells are amongst the top candidates for economically viable terrestrial and space based power generation. Despite very low federal funding during the eighties, amorphous silicon solar cell efficiencies have continually been improved - from a low 3 percent to over 13 percent now. Further improvements have been made by the use of multi-junction tandem solar cells. Efficiencies close to 15 percent have been achieved in several labs. In order to be competitive with fossil fuel generated electricity, it is believed that module efficiency of 15 percent or cell efficiency of 20 percent is required. Thus, further improvements in cell performance is imperative. One major problem that was discovered almost 15 years ago in amorphous silicon devices is the well known Staebler-Wronski Effect. Efficiency of amorphous silicon solar cells was found to degrade upon exposure to sunlight. Until now their is no consensus among the scientists on the mechanism for this degradation. Efficiency may degrade anywhere from 10 percent to almost 50 percent within the first few months of operation. In order to improve solar cell efficiencies, it is clear that the cause or causes of such degradation must be found and the processing conditions altered to minimize the loss in efficiency. This project was initiated in 1987 to investigate a possible link between metallic impurities, in particular, Ag, and this degradation. Such a link was established by one of the NASA scientists for the light induced degradation of n+/p crystalline silicon solar cells.

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

PubMed

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

2016-01-01

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

Effect of ultrasonic frequency on degradation of methylene blue in the presence of particle

NASA Astrophysics Data System (ADS)

Kobayashi, Daisuke; Suzuki, Atsushi; Takahashi, Tomoki; Matsumoto, Hideyuki; Kuroda, Chiaki; Otake, Katsuto; Shono, Atsushi

2012-05-01

Techniques for the degradation of hazardous organic compounds have been investigated such as solvent extraction, incineration, chemical dehalogenation and biodegradation, etc. Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. In addition, the sonochemical reaction is enhanced by particle addition. However, the enhancement mechanism of particle addition has not been investigated well, because ultrasound enhances not only chemical reaction but also mass transfer. In this study, the degradation process of methylene blue as the model hazardous organic compound by ultrasonic irradiation was investigated. The effects of ultrasonic irradiation condition on degradation rate were investigated. The effect of ultrasonic frequency on improvement of degradation reaction by particle addition was also investigated. In addition, the effects of ultrasonic frequency on ultrasonic power and chemical efficiency were investigated by calorimetry and SE value. The degradation rate constants were estimated from the results of temporal change of the concentration of methylene blue assuming first order kinetics for the decomposition. There was a linear relation in the degradation rate and the ultrasonic power. In addition, the degradation rates at 127 kHz and 490 kHz were much larger than that at 22.8 kHz. The effect of ultrasonic frequency on sonochemical efficiency has been investigated, and the sonochemical effects in the range of frequency of 200 - 500 kHz are 10 times larger than those in the lower or higher frequency regions. Therefore, the degradation rate of methylene blue was considered to estimate using sonochemical efficiency. The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle. On the other hand, the enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and species of particle. The relationship between particle size and resonance diameter of ultrasound is considered to influence the enhancement of ultrasonic degradation process.

The field experiments and model of the natural dust deposition effects on photovoltaic module efficiency.

PubMed

Jaszczur, Marek; Teneta, Janusz; Styszko, Katarzyna; Hassan, Qusay; Burzyńska, Paulina; Marcinek, Ewelina; Łopian, Natalia

2018-04-20

The maximisation of the efficiency of the photovoltaic system is crucial in order to increase the competitiveness of this technology. Unfortunately, several environmental factors in addition to many alterable and unalterable factors can significantly influence the performance of the PV system. Some of the environmental factors that depend on the site have to do with dust, soiling and pollutants. In this study conducted in the city centre of Kraków, Poland, characterised by high pollution and low wind speed, the focus is on the evaluation of the degradation of efficiency of polycrystalline photovoltaic modules due to natural dust deposition. The experimental results that were obtained demonstrated that deposited dust-related efficiency loss gradually increased with the mass and that it follows the exponential. The maximum dust deposition density observed for rainless exposure periods of 1 week exceeds 300 mg/m 2 and the results in efficiency loss were about 2.1%. It was observed that efficiency loss is not only mass-dependent but that it also depends on the dust properties. The small positive effect of the tiny dust layer which slightly increases in surface roughness on the module performance was also observed. The results that were obtained enable the development of a reliable model for the degradation of the efficiency of the PV module caused by dust deposition. The novelty consists in the model, which is easy to apply and which is dependent on the dust mass, for low and moderate naturally deposited dust concentration (up to 1 and 5 g/m 2 and representative for many geographical regions) and which is applicable to the majority of cases met in an urban and non-urban polluted area can be used to evaluate the dust deposition-related derating factor (efficiency loss), which is very much sought after by the system designers, and tools used for computer modelling and system malfunction detection.

Biodegradation of organic pollutants in saline wastewater by halophilic microorganisms: a review.

PubMed

Castillo-Carvajal, Laura C; Sanz-Martín, José Luis; Barragán-Huerta, Blanca E

2014-01-01

Agro-food, petroleum, textile, and leather industries generate saline wastewater with a high content of organic pollutants such as aromatic hydrocarbons, phenols, nitroaromatics, and azo dyes. Halophilic microorganisms are of increasing interest in industrial waste treatment, due to their ability to degrade hazardous substances efficiently under high salt conditions. However, their full potential remains unexplored. The isolation and identification of halophilic and halotolerant microorganisms from geographically unrelated and geologically diverse hypersaline sites supports their application in bioremediation processes. Past investigations in this field have mainly focused on the elimination of polycyclic aromatic hydrocarbons and phenols, whereas few studies have investigated N-aromatic compounds, such as nitro-substituted compounds, amines, and azo dyes, in saline wastewater. Information regarding the growth conditions and degradation mechanisms of halophilic microorganisms is also limited. In this review, we discuss recent research on the removal of organic pollutants such as organic matter, in terms of chemical oxygen demand (COD), dyes, hydrocarbons, N-aliphatic and N-aromatic compounds, and phenols, in conditions of high salinity. In addition, some proposal pathways for the degradation of aromatic compounds are presented.

Photodegradation of organic pollutants using N-titanium oxide catalyst.

PubMed

Shinde, S S; Bhosale, C H; Rajpure, K Y

2014-12-01

Photoelectrocatalytic degradation of typical aromatic compounds with persistent reaction rate is studied using thin layers of N-titanium dioxide deposited on transparent and conducting glass substrates. Backside illuminated flow-through parallel plate photoelectrochemical reactors is used and electrical bias for suppressing charge carrier recombination is applied externally. The degradation experiments are performed under solar irradiation with the conditions aimed at reducing contaminant concentrations to maximal tolerated levels as specified under environmental regulations. From the observed COD-time relations, rate constants normalized to unit volume and photocurrent (kinetic parameters), characterizing the efficiency of the electrochemical oxidation process involving photogenerated valence band holes or their immediate reaction products, are calculated and compared to the decrease of optical extinction of the solutions. The parameters for salicylic acid, 4-chlorophenol, benzoic acid and oxalic acid are found to decrease as the main absorption peaks of these substances diminish in due course of degradation reaction. In order to realize a complete mineralization of such compounds, which should be an ultimate aim of water purification, COD and TOC is analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

Solvothermal synthesis of P25/Bi2WO6 nanocomposite photocatalyst and photocatalytic degradation of ethylene under visible light

NASA Astrophysics Data System (ADS)

Song, Xianliang; Wang, Haidan; Li, Yingying; Ye, Shengying; Dionysiou, Dionysios D.

2018-05-01

P25/Bi2WO6 nanocomposite photocatalysts were synthesized by solvothermal method, and their photocatalytic activities were evaluated for the degradation of ethylene under visible light irradiation. The results show that P25/Bi2WO6 nanocomposites have higher photocatalytic activity than P25 and pure Bi2WO6. When the loading amount of P25 is 35%, the photocatalytic degradation of ethylene under visible light is the highest, which is 4.5 and 2.2 times higher than that of P25 and Bi2WO6, respectively. The improvement of the photocatalytic activity of the nanocomposite is mainly due to the formation of the staggered heterojunctions in the contact interface of P25 and Bi2WO6. This can refine the grain and produce lattice defects in the interface of the composite, which could provide more active sites. Therefore, the separation efficiency of the photogenerated electron-hole pair is improved, and the spectral response range is extended to the visible light region, thereby the absorption and utilization of light energy is improved.

Improvement of ethanol production from crystalline cellulose via optimizing cellulase ratios in cellulolytic Saccharomyces cerevisiae.

PubMed

Liu, Zhuo; Inokuma, Kentaro; Ho, Shih-Hsin; den Haan, Riaan; van Zyl, Willem H; Hasunuma, Tomohisa; Kondo, Akihiko

2017-06-01

Crystalline cellulose is one of the major contributors to the recalcitrance of lignocellulose to degradation, necessitating high dosages of cellulase to digest, thereby impeding the economic feasibility of cellulosic biofuels. Several recombinant cellulolytic yeast strains have been developed to reduce the cost of enzyme addition, but few of these strains are able to efficiently degrade crystalline cellulose due to their low cellulolytic activities. Here, by combining the cellulase ratio optimization with a novel screening strategy, we successfully improved the cellulolytic activity of a Saccharomyces cerevisiae strain displaying four different synergistic cellulases on the cell surface. The optimized strain exhibited an ethanol yield from Avicel of 57% of the theoretical maximum, and a 60% increase of ethanol titer from rice straw. To our knowledge, this work is the first optimization of the degradation of crystalline cellulose by tuning the cellulase ratio in a cellulase cell-surface display system. This work provides key insights in engineering the cellulase cocktail in a consolidated bioprocessing yeast strain. Biotechnol. Bioeng. 2017;114: 1201-1207. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Synthetic Gene Network with Positive Feedback Loop Amplifies Cellulase Gene Expression in Neurospora crassa.

PubMed

Matsu-Ura, Toru; Dovzhenok, Andrey A; Coradetti, Samuel T; Subramanian, Krithika R; Meyer, Daniel R; Kwon, Jaesang J; Kim, Caleb; Salomonis, Nathan; Glass, N Louise; Lim, Sookkyung; Hong, Christian I

2018-05-18

Second-generation or lignocellulosic biofuels are a tangible source of renewable energy, which is critical to combat climate change by reducing the carbon footprint. Filamentous fungi secrete cellulose-degrading enzymes called cellulases, which are used for production of lignocellulosic biofuels. However, inefficient production of cellulases is a major obstacle for industrial-scale production of second-generation biofuels. We used computational simulations to design and implement synthetic positive feedback loops to increase gene expression of a key transcription factor, CLR-2, that activates a large number of cellulases in a filamentous fungus, Neurospora crassa. Overexpression of CLR-2 reveals previously unappreciated roles of CLR-2 in lignocellulosic gene network, which enabled simultaneous induction of approximately 50% of 78 lignocellulosic degradation-related genes in our engineered Neurospora strains. This engineering results in dramatically increased cellulase activity due to cooperative orchestration of multiple enzymes involved in the cellulose degradation pathway. Our work provides a proof of principle in utilizing mathematical modeling and synthetic biology to improve the efficiency of cellulase synthesis for second-generation biofuel production.

A novel health indicator for on-line lithium-ion batteries remaining useful life prediction

NASA Astrophysics Data System (ADS)

Zhou, Yapeng; Huang, Miaohua; Chen, Yupu; Tao, Ye

2016-07-01

Prediction of lithium-ion batteries remaining useful life (RUL) plays an important role in an intelligent battery management system. The capacity and internal resistance are often used as the batteries health indicator (HI) for quantifying degradation and predicting RUL. However, on-line measurement of capacity and internal resistance are hardly realizable due to the not fully charged and discharged condition and the extremely expensive cost, respectively. Therefore, there is a great need to find an optional way to deal with this plight. In this work, a novel HI is extracted from the operating parameters of lithium-ion batteries for degradation modeling and RUL prediction. Moreover, Box-Cox transformation is employed to improve HI performance. Then Pearson and Spearman correlation analyses are utilized to evaluate the similarity between real capacity and the estimated capacity derived from the HI. Next, both simple statistical regression technique and optimized relevance vector machine are employed to predict the RUL based on the presented HI. The correlation analyses and prediction results show the efficiency and effectiveness of the proposed HI for battery degradation modeling and RUL prediction.

Effects of atmospheric turbulence on the imaging performance of optical system

NASA Astrophysics Data System (ADS)

Al-Hamadani, Ali H.; Zainulabdeen, Faten Sh.; Karam, Ghada Sabah; Nasir, Eman Yousif; Al-Saedi, Abaas

2018-05-01

Turbulent effects are very complicated and still not entirely understood. Light waves from an astronomical object are distorted as they pass through the atmosphere. The refractive index fluctuations in the turbulent atmosphere induce an optical path difference (OPD) between different parts of the wavefront, distorted wavefronts produce low-quality images and degrade the image beyond the diffraction limit. In this paper the image degradation due to 2-D Gaussian atmospheric turbulence is considered in terms of the point spread function (PSF), and Strehl ratio as an image quality criteria for imaging systems with different apertures using the pupil function teqneque. A general expression for the degraded PSF in the case of circular and square apertures (with half diagonal = √{π/2 } , and 1) diffraction limited and defocused optical system is considered. Based on the derived formula, the effect of the Gaussian atmospheric turbulence on circular and square pupils has been studied with details. Numerical results show that the performance of optical systems with square aperture is more efficient at high levels of atmospheric turbulence than the other apertures.

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.

Pilot-Scale Silicone Process for Low-Cost Carbon Dioxide Capture. Final Scientific/Technical Report

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

Hancu, Dan; Wood, Benjamin; Genovese, Sarah

GE Global Research has developed, over the last 8 years, a platform of cost effective CO 2 capture technologies based on a non-aqueous aminosilicone solvent (GAP-1m). As demonstrated in a previous funded DOE project (DE-FE0007502), the GAP-1m solvent has increased CO 2 working capacity, lower volatility and corrosivity than the benchmark aqueous amine technology. The current report describes the cooperative program between GE Global Research (GE GRC), and the National Carbon Capture Center (NCCC) to design, construct, and operate a pilot-scale process using GAP-1m solvent to demonstrate its performance at 0.5 MWe. (i) Performance of the GAP-1m solvent was demonstratedmore » in a 0.5 MWe pilot with real flue gas for over 900 hrs. of operation using two alternative desorption designs: a Continuous Stirred Tank Reactor (CSTR), and a Steam Stripper Column (SSC). The CSTR is a one-stage separation unit with reduced space requirements, and capital cost. The alternative is a multi-stage separation column, with improved desorption efficiency. Testing the two desorber options allowed us to identify the most cost effective, and space efficient desorber solution. (ii) CSTR Campaign: The CSTR desorber unit was designed, fabricated and integrated with the pilot solvent test unit (PSTU), replacing the PSTU Steam Stripper Column at NCCC. Solvent management and waste water special procedures were implemented to accommodate operation of the non-aqueous solvent in the PSTU. Performance of the GAP-1m solvent with the CSTR was demonstrated for over 500 hrs. while varying temperature of the desorption (230 – 265 oF), solvent circulation rate (GAP-1m : CO 2 (molar) = 1.5 – 4), and flue gas flow rates (0.2 – 0.5 MWe). Solvent carry-over in the CO 2 product was minimized by maintaining water content below 5 wt.%, and desorption pressure at 7 psig. CO 2 capture efficiency achieved was 95% at 0.25 MWe (GAP-1m : CO 2 = 4 (molar), 230 oF desorption), and 65% at 0.5 MWe (GAP-1m : CO 2 (molar) = 1.5, 248 oF). Solvent loss was dominated by thermal degradation of the rich solvent. (iii) Steam Stripper Column Campaign: Higher expected cost of the solvent vs. aqueous amines makes solvent management a top priority to maintain the low cost for the process. During the testing of the GAP-1m solvent with the CSTR, thermal degradation of the rich solvent was found to be the main mechanism in solvent loss. Small amounts of water in the working solution were found to be an effective way to enable steam stripping, thereby lowering desorption temperature, and hence reducing thermal degradation. Steam stripping also increased working capacity by 30% due to a more efficient desorption. The concept was first tested in a glass stripping column (lab scale, GE GRC), optimized in a continuous bench scale system (2 kWe, GE GRC), and demonstrated in a 0.5 MWe PSTU at NCCC. No special system modifications were required to the PSTU to accommodate the testing of the non-aqueous GAP-1 solvent with the regenerator column. SSC was found to be more robust towards solvent entrainment (H 2O < 35 wt.%). 90 – 95% CO 2 capture efficiency was achieved under stoichiometric conditions at 0.5 MWe (235 oF desorption, 2 psig and 19 wt. % H 2O). Both CO 2 capture efficiency and specific duty reached optimum conditions at 18 wt.% H 2O. Low amine degradation (< 0.05 wt.%/day) was recorded over 350 hrs. of operation. Controlled water addition to GAP-1m solvent decreased the desorption temperature, thermal degradation, and improved the CO 2 working capacity due to more efficient absorption and desorption processes. Under these conditions, the GAP-1m solvent exhibited a 25% increased working capacity, and 10% reduction in specific steam duty vs. MEA, at 10 oF lower desorption temperature. (iv) Techno-economic Analysis: The pilot-scale PSTU engineering data were used to update the capture system process models, and the techno-economic analysis was performed for a 550 MW coal fired power plant. The 1st year CO 2 removal cost for the aminosilicone-based carbon-capture process was evaluated at $48/ton CO 2 using the steam stripper column. This is a 20% reduction compared to MEA, primarily due to lower overall capital cost. CO 2 cost using the CSTR desorber is dominated by the economics of the solvent make-up. The steam stripper desorber is the preferred unit operation due to a more efficient desorption, and reduced solvent make-up rate. Further reduction in CO 2 capture cost is expected by lowering the manufacturing cost of the solvent, implementing flowsheet optimization and/or implementing the next generation aminosilicone solvent with improved stability and increased CO 2 working capacity.« less

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

PubMed

Rahimi, Sajad; Ayati, Bita; Rezaee, Abbas

2016-06-01

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

Interfacial engineering of electron transport layer using Caesium Iodide for efficient and stable organic solar cells

NASA Astrophysics Data System (ADS)

Upama, Mushfika Baishakhi; Elumalai, Naveen Kumar; Mahmud, Md Arafat; Wright, Matthew; Wang, Dian; Xu, Cheng; Haque, Faiazul; Chan, Kah Howe; Uddin, Ashraf

2017-09-01

Polymer solar cells (PSCs) have gained immense research interest in the recent years predominantly due to low-cost, solution process-ability, and facile device fabrication. However, achieving high stability without compromising the power conversion efficiency (PCE) serves to be an important trade-off for commercialization. In line with this, we demonstrate the significance of incorporating a CsI/ZnO bilayer as electron transport layer (ETL) in the bulk heterojunction PSCs employing low band gap polymer (PTB7) and fullerene (PC71BM) as the photo-active layer. The devices with CsI/ZnO interlayer exhibited substantial enhancement of 800% and 12% in PCE when compared to the devices with pristine CsI and pristine ZnO as ETL, respectively. Furthermore, the UV and UV-ozone induced degradation studies revealed that the devices incorporating CsI/ZnO bilayer possess excellent decomposition stability (∼23% higher) over the devices with pristine ZnO counterparts. The incorporation of CsI between ITO and ZnO was found to favorably modify the energy-level alignment at the interface, contributing to the charge collection efficiency as well as protecting the adjacent light absorbing polymer layers from degradation. The mechanism behind the improvement in PCE and stability is analyzed using the electrochemical impedance spectroscopy and dark I-V characteristics.

Photocatalytic degradation of furfural in aqueous solution by N-doped titanium dioxide nanoparticles.

PubMed

Veisi, Farzaneh; Zazouli, Mohammad Ali; Ebrahimzadeh, Mohammad Ali; Charati, Jamshid Yazdani; Dezfoli, Amin Shiralizadeh

2016-11-01

The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO 2 /Sun and N-TiO 2 /UV) in a lab-scale batch photoreactor. The N-TiO 2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO 2 /UV and N-TiO 2 /Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO 2 /UV process was higher than that using the N-TiO 2 /Sun process.

Silicon Carbide Radioisotope Batteries

NASA Technical Reports Server (NTRS)

Rybicki, George C.

2005-01-01

The substantial radiation resistance and large bandgap of SiC semiconductor materials makes them an attractive candidate for application in a high efficiency, long life radioisotope battery. To evaluate their potential in this application, simulated batteries were constructed using SiC diodes and the alpha particle emitter Americium Am-241 or the beta particle emitter Promethium Pm-147. The Am-241 based battery showed high initial power output and an initial conversion efficiency of approximately 16%, but the power output decayed 52% in 500 hours due to radiation damage. In contrast the Pm-147 based battery showed a similar power output level and an initial conversion efficiency of approximately 0.6%, but no degradation was observed in 500 hours. However, the Pm-147 battery required approximately 1000 times the particle fluence as the Am-242 battery to achieve a similar power output. The advantages and disadvantages of each type of battery and suggestions for future improvements will be discussed.

Mesoporous Ga-TiO₂: Role of Oxygen Vacancies for the Photocatalytic Degradation Under Visible Light.

PubMed

Myilsamy, M; Mahalakshmi, M; Subha, N; Murugesan, V

2018-02-01

Gallium doped mesoporous TiO2 with different weight percentages were synthesized by sol-gel method using Pluronic P123 as the structure directing template. The physico-chemical properties of all the synthesized catalysts were determined by XRD, TEM, SEM-EDAX, N2 adsorption-desorption studies, XPS, UV-vis DRS, FT-IR and photoluminescence spectroscopy. 1.0 wt% Ga-TiO2 exhibited the highest photocatalytic efficiency among all the synthesized materials under visible light due to the high surface area, reduced band gap and suppressed electron-hole recombination. Ga3+ ions substitutions for Ti4+ ions in TiO2 lattice created oxygen vacancies in TiO2 lattice, which created a defect energy level below the conduction band of TiO2 and hence the band gap was reduced. The oxygen vacancy defects was playing significant role to improve the adsorption of oxygen molecules, hydroxide ions and cationic rhodamine B (RhB) on TiO2 surface in an aqueous medium. The lifetime of the charge carriers was also enhanced by trapping the photogenerated electrons in oxygen vacancies and transferring them to the adsorbed O2 to produce superoxide anion radicals (O-. 2 ). The photo-induced holes at valence band reduced the adsorbed OH- ions and produced a large number of .OH radicals, which subsequently degraded the RhB. Hence oxygen vacancies created by gallium doping on TiO2 enhanced the photocatalytic efficiency for the degradation of RhB under visible light.

Biofiltration of gasoline and ethanol-amended gasoline vapors.

PubMed

Soares, Marlene; Woiciechowski, Adenise L; Kozliak, Evguenii I; Paca, Jan; Soccol, Carlos R

2012-01-01

Assuming the projected increase in use of ethanol as a biofuel, the current study was conducted to compare the biofiltration efficiencies for plain and 25% ethanol-containing gasoline. Two biofilters were operated in a downflow mode for 7 months, one of them being compost-based whereas the other using a synthetic packing material, granulated tire rubber, inoculated with gasoline-degrading microorganisms. Inlet concentrations measured as total hydrocarbon (TH) ranged from 1.9 to 5.8 g m(-3) at a constant empty bed retention time of 6.84 min. Contrary to the expectations based on microbiological considerations, ethanol-amended gasoline was more readily biodegraded than plain hydrocarbons, with the respective steady state elimination capacities of 26-43 and 14-18 gTH m(-3) h(-1) for the compost biofilter. The efficiency of both biofilters significantly declined upon the application of higher loads of plain gasoline, yet immediately recovering when switched back to ethanol-blended gasoline. The unexpected effect of ethanol in promoting gasoline biodegradation was explained by increasing hydrocarbon partitioning into the aqueous phase, with mass transfer being rate limiting for the bulk of components. The tire rubber biofilter, after a long acclimation, surpassed the compost biofilter in performance, presumably due to the 'buffering' effect of this packing material increasing the accessibility of gasoline hydrocarbons to the biofilm. With improved substrate mass transfer, biodegradable hydrocarbons were removed in the tire rubber biofilter's first reactor stage, with most of the remaining poorly degradable smaller-size hydrocarbons being degraded in the second stage.

Reactive Black 5 as electron donor and/or electron acceptor in dual chamber of solar photocatalytic fuel cell.

PubMed

Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusuf, Sara Yasina; Yusoff, NikAthirah; Lee, Sin-Li

2018-07-01

The role of azo dye Reactive Black 5 (RB5) as an electron donor and/or electron acceptor could be distinguished in dual chamber of photocatalytic fuel cell (PFC). The introduction of RB5 in anode chamber increased the voltage generation in the system since degradation of RB5 might produce electrons which also would transfer through external circuit to the cathode chamber. The removal efficiency of RB5 with open and closed circuit was 8.5% and 13.6%, respectively and removal efficiency for open circuit was low due to the fact that recombination of electron-hole pairs might happen in anode chamber since without connection to the cathode, electron cannot be transferred. The degradation of RB5 in cathode chamber with absence of oxygen showed that electrons from anode chamber was accepted by dye molecules to break its azo bond. The presence of oxygen in cathode chamber would improve the oxygen reduction rate which occurred at Platinum-loaded carbon (Pt/C) cathode electrode. The V oc , J sc and P max for different condition of ultrapure water at cathode chamber also affected their fill factor. The transportation of protons to cathode chamber through Nafion membrane could decrease the pH of ultrapure water in cathode chamber and undergo hydrogen evolution reaction in the absence of oxygen which then increased degradation rate of RB5 as well as its electricity generation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of eco-physiological indicators in Northeast Asia dryland regions based on MODIS products and ecological models

NASA Astrophysics Data System (ADS)

Kang, W.

2017-12-01

Ecosystem carbon-energy-water circles have significant effect on function and structure and vice verse. Based on these circles mechanism, some eco-physiological indicators, like Transpiration (T), gross primary productivity (GPP), light use efficiency (LUE) and water use efficiency (WUE), are commonly applied to assess terrestrial ecosystem function and structure dynamics. The ecosystem weakened function and simple structure in Northeast dryland regions resulted from land degradation or desertification, which could be demonstrated by above-mentioned indicators. In this study, based on MODIS atmosphere (MYD07, MYD04, MYD06 data) and land products (MYD13A2 NDVI, MYD11A1 LST, MYD15A2 LAI and land cover data), we first retrieved transpiration and LUE via Penman-Monteith Model and modified Vegetation Photosynthesis Model (VPM), respectively; and then evaluated dynamics of these eco-physiological indicators (Tair, VPD, T, LUE, GPP and WUE) and some hotspots were found for next land degradation assessment. The results showed: (1) LUE and WUE are lower in barren or sparsely vegetated area and grasslands than in forest and croplands. (2) Whereas, all indicators presented higher variability in grassland area, particularly in east Mongolia. (3) GPP and transpiration have larger variability than other indicators due to fraction of absorbed Photosynthetically active radiation (FPAR). These eco-physiological indicators are expected to continue to change under future climate change and to help to assess land degradation from ecosystem energy-water-carbon perspectives.

Hydrocarbon degradation and plant colonization of selected bacterial strains isolated from the rhizsophere and plant interior of Italian ryegrass and Birdsfoot trefoil

NASA Astrophysics Data System (ADS)

Sohail, Y.; Andria, V.; Reichenauer, T. G.; Sessitsch, A.

2009-04-01

Hydrocarbon-degrading strains were isolated from the rhizosphere, root and shoot interior of Italian ryegrass (Lolium multiflorum var. Taurus), Birdsfoot trefoil (Lotus corniculatus var. Leo) grown in a soil contaminated with petroleum oil. Strains were tested regarding their phylogeny and their degradation efficiency. The most efficient strains were tested regarding their suitability to be applied for phytoremediation of diesel oils. Sterilized and non-sterilized agricultural soil, with and with out compost, were spiked with diesel and used for planting Italian ryegrass and birdsfoot trefoil. Four selected strains with high degradation activities, derived from the rhizosphere and plant interior, were selected for individual inoculation. Plants were harvested at flowering stage and plant biomass and hydrocarbon degradation was determined. Furthermore, it was investigated to which extent the inoculant strains were able to survive and colonize plants. Microbial community structures were analysed by 16S rRNA and alkB gene analysis. Results showed efficient colonization by the inoculant strains and improved degradation by the application of compost combined with inoculation as well as on microbial community structures will be presented.

Recent progress in degradation and stabilization of organic solar cells

NASA Astrophysics Data System (ADS)

Cao, Huanqi; He, Weidong; Mao, Yiwu; Lin, Xiao; Ishikawa, Ken; Dickerson, James H.; Hess, Wayne P.

2014-10-01

Stability is of paramount importance in organic semiconductor devices, especially in organic solar cells (OSCs). Serious degradation in air limits wide applications of these flexible, light-weight and low-cost power-generation devices. Studying the stability of organic solar cells will help us understand degradation mechanisms and further improve the stability of these devices. There are many investigations into the efficiency and stability of OSCs. The efficiency and stability of devices even of the same photoactive materials are scattered in different papers. In particular, the extrinsic degradation that mainly occurs near the interface between the organic layer and the cathode is a major stability concern. In the past few years, researchers have developed many new cathodes and cathode buffer layers, some of which have astonishingly improved the stability of OSCs. In this review article, we discuss the recent developments of these materials and summarize recent progresses in the study of the degradation/stability of OSCs, with emphasis on the extrinsic degradation/stability that is related to the intrusion of oxygen and water. The review provides detailed insight into the current status of research on the stability of OSCs and seeks to facilitate the development of highly-efficient OSCs with enhanced stability.

High activity of g-C3N4/multiwall carbon nanotube in catalytic ozonation promotes electro-peroxone process.

PubMed

Guo, Zhuang; Cao, Hongbin; Wang, Yuxian; Xie, Yongbing; Xiao, Jiadong; Yang, Jin; Zhang, Yi

2018-06-01

Three kinds of graphitic carbon nitride materials (bulk, porous and nanosheet g-C 3 N 4 ) were composited with a multiwall carbon nanotube (MWCNT) by a hydrothermal method, and the obtained b-C 3 N 4 /CNT, p-C 3 N 4 /CNT and n-C 3 N 4 /CNT materials were used in the electrodes for electro-peroxone process. It was found that the n-C 3 N 4 /CNT composite exhibited the highest efficiency in oxalate degradation, though it performed the worst in the oxygen-reduction reaction for H 2 O 2 production. The n-C 3 N 4 /CNT composite exhibited higher activity than CNT and other composites in catalytic ozonation experiments, due to the higher pyrrolic-N content modified on the CNT surface and higher surface area. It also has higher electron transfer ability, which benefited to the electro-reduction of both O 2 and O 3 . The result confirmed that catalytic ozonation process was an important means to enhance the degradation efficiency in the electro-peroxone process, besides peroxone process and O 3 -electrolysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Radiolytic degradation of a new diglycol-diamide ligand for actinide and lanthanide co-extraction from spent nuclear fuel

NASA Astrophysics Data System (ADS)

Ossola, Annalisa; Macerata, Elena; Tinonin, Dario A.; Faroldi, Federica; Giola, Marco; Mariani, Mario; Casnati, Alessandro

2016-07-01

Within the Partitioning and Transmutation strategies, great efforts have been devoted in the last decades to the development of lipophilic ligands able to co-extract trivalent Lanthanides (Ln) and Actinides (An) from spent nuclear fuel. Because of the harsh working conditions these ligands undergo, it is important to prove their chemical and radiolytic stability during the counter-current multi-stage extraction process. In the present work the hydrolytic and radiolytic resistance of the freshly prepared and aged organic solutions containing the new ligand (2,6-bis[(N-methyl-N-dodecyl)carboxamide]-4-methoxy-tetrahydro-pyran) were investigated in order to evaluate the impact on the safety and efficiency of the process. Liquid-liquid extraction tests with spiked solutions showed that the ligand extracting performances are strongly impaired by storing the samples at room temperature and in the light. Moreover, the extracting efficiency of the irradiated samples resulted to be influenced by gamma irradiation, while selectivity remains unchanged. Preliminary mass spectrometric data showed that degradation is mainly due to the acid-catalysed reaction of the ligand carboxamide and ether groups with the 1-octanol present in the diluent.

Enhancing the Photovoltaic Performance of Perovskite Solar Cells with a Down-Conversion Eu-Complex.

PubMed

Jiang, Ling; Chen, Wangchao; Zheng, Jiawei; Zhu, Liangzheng; Mo, Li'e; Li, Zhaoqian; Hu, Linhua; Hayat, Tasawar; Alsaedi, Ahmed; Zhang, Changneng; Dai, Songyuan

2017-08-16

Organometal halide perovskite solar cells (PSCs) have shown high photovoltaic performance but poor utilization of ultraviolet (UV) irradiation. Lanthanide complexes have a wide absorption range in the UV region and they can down-convert the absorbed UV light into visible light, which provides a possibility for PSCs to utilize UV light for higher photocurrent, efficiency, and stability. In this study, we use a transparent luminescent down-converting layer (LDL) of Eu-4,7-diphenyl-1,10-phenanthroline (Eu-complex) to improve the light utilization efficiency of PSCs. Compared with the uncoated PSC, the PSC coated with Eu-complex LDL on the reverse of the fluorine-doped tin oxide glass displayed an enhancement of 11.8% in short-circuit current density (J sc ) and 15.3% in efficiency due to the Eu-complex LDL re-emitting UV light (300-380 nm) in the visible range. It is indicated that the Eu-complex LDL plays the role of enhancing the power conversion efficiency as well as reducing UV degradation for PSCs.

Optical determination of Shockley-Read-Hall and interface recombination currents in hybrid perovskites

PubMed Central

Sarritzu, Valerio; Sestu, Nicola; Marongiu, Daniela; Chang, Xueqing; Masi, Sofia; Rizzo, Aurora; Colella, Silvia; Quochi, Francesco; Saba, Michele; Mura, Andrea; Bongiovanni, Giovanni

2017-01-01

Metal-halide perovskite solar cells rival the best inorganic solar cells in power conversion efficiency, providing the outlook for efficient, cheap devices. In order for the technology to mature and approach the ideal Shockley-Queissier efficiency, experimental tools are needed to diagnose what processes limit performances, beyond simply measuring electrical characteristics often affected by parasitic effects and difficult to interpret. Here we study the microscopic origin of recombination currents causing photoconversion losses with an all-optical technique, measuring the electron-hole free energy as a function of the exciting light intensity. Our method allows assessing the ideality factor and breaks down the electron-hole recombination current into bulk defect and interface contributions, providing an estimate of the limit photoconversion efficiency, without any real charge current flowing through the device. We identify Shockley-Read-Hall recombination as the main decay process in insulated perovskite layers and quantify the additional performance degradation due to interface recombination in heterojunctions. PMID:28317883

Thermally stable, highly efficient, ultraflexible organic photovoltaics

PubMed Central

Xu, Xiaomin; Fukuda, Kenjiro; Karki, Akchheta; Park, Sungjun; Kimura, Hiroki; Jinno, Hiroaki; Watanabe, Nobuhiro; Yamamoto, Shuhei; Shimomura, Satoru; Kitazawa, Daisuke; Yokota, Tomoyuki; Umezu, Shinjiro; Nguyen, Thuc-Quyen; Someya, Takao

2018-01-01

Flexible photovoltaics with extreme mechanical compliance present appealing possibilities to power Internet of Things (IoT) sensors and wearable electronic devices. Although improvement in thermal stability is essential, simultaneous achievement of high power conversion efficiency (PCE) and thermal stability in flexible organic photovoltaics (OPVs) remains challenging due to the difficulties in maintaining an optimal microstructure of the active layer under thermal stress. The insufficient thermal capability of a plastic substrate and the environmental influences cannot be fully expelled by ultrathin barrier coatings. Here, we have successfully fabricated ultraflexible OPVs with initial efficiencies of up to 10% that can endure temperatures of over 100 °C, maintaining 80% of the initial efficiency under accelerated testing conditions for over 500 hours in air. Particularly, we introduce a low-bandgap poly(benzodithiophene-cothieno[3,4-b]thiophene) (PBDTTT) donor polymer that forms a sturdy microstructure when blended with a fullerene acceptor. We demonstrate a feasible way to adhere ultraflexible OPVs onto textiles through a hot-melt process without causing severe performance degradation. PMID:29666257

The characterization of secondary lithium-ion battery degradation when operating complex, ultra-high power pulsed loads

NASA Astrophysics Data System (ADS)

Wong, Derek N.

The US Navy is actively developing all electric fleets, raising serious questions about what is required of onboard power supplies in order to properly power the ship's electrical systems. This is especially relevant when choosing a viable power source to drive high power propulsion and electric weapon systems in addition to the conventional loads deployed aboard these types of vessels. Especially when high pulsed power loads are supplied, the issue of maintaining power quality becomes important and increasingly complex. Conventionally, a vessel's electrical power is generated using gas turbine or diesel driven motor-generator sets that are very inefficient when they are used outside of their most efficient load condition. What this means is that if the generator is not being utilized continuously at its most efficient load capacity, the quality of the output power may also be effected and fall outside of the acceptable power quality limits imposed through military standards. As a solution to this potential problem, the Navy has proposed using electrochemical storage devices since they are able to buffer conventional generators when the load is operating below the generator's most efficient power level or able to efficiently augment a generator when the load is operating in excess of the generator's most efficient power rating. Specifically, the US Navy is interested in using commercial off-the-shelf (COTS) lithium-ion batteries within an intelligently controlled energy storage module that could act as either a prime power supply for on-board pulsed power systems or as a backup generator to other shipboard power systems. Due to the unique load profile of high-rate pulsed power systems, the implementation of lithium-ion batteries within these complex systems requires them to be operated at very high rates and the effects these things have on cell degradation has been an area of focus. There is very little published research into the effects that high power transient or pulsed loading has on the degradation mechanisms of secondary lithium-ion cells. Prior to performing this work, it was unclear if the implementation of lithium-ion batteries in highly transient load conditions at high rate would accelerate cell degradation mechanisms that have been previously considered as minor issues. This work has focused on answering these previously unanswered questions. In early experiments performed here, COTS lithium-iron-phosphate (LFP) cells were studied under high-rate, transient load conditions and it was found that their capacity fade deviated from the traditional linear behavior and exponentially declined until no charge could be accepted when recharge was attempted at high rate. These findings indicated that subjecting LFP chemistries to transient, high rate charge/discharge profiles induced rapid changes in the electrode/electrolyte interface that rendered the cells useless when high rate recharge was required. These findings suggested there was more phenomena to learn about how these cells degraded under high rate pulsed conditions before they are fielded in Naval applications. Therefore, the research presented here has been focused on understanding the degradation mechanisms that are unique to LFP cells when they are cycled under pulsed load profiles at high charge and discharge rates. In particular, the work has been focused on identifying major degradation reactions that occur by studying the surface chemistry of cycled electrode materials. Efforts have been performed to map the impedance evolution of both cathode and anode half cells, respectively, using a novel three electrode technique that was developed for this research. Using this technique, the progression of degradation has been mapped using analysis of differential capacitance spectrums. In both the three electrode EIS mapping and differential capacitance analysis that has been performed, electrical component models have been developed. The results presented will show that there are unique degradation mechanisms induced through high rate pulsed loading conditions that are not normally seen in low rate continuous cycling of LFP cells.

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.

Method of differential-phase/absolute-amplitude QAM

DOEpatents

Dimsdle, Jeffrey William [Overland Park, KS

2007-07-03

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Method of differential-phase/absolute-amplitude QAM

DOEpatents

Dimsdle, Jeffrey William [Overland Park, KS

2008-10-21

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Method of differential-phase/absolute-amplitude QAM

DOEpatents

Dimsdle, Jeffrey William [Overland Park, KS

2009-09-01

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Method of differential-phase/absolute-amplitude QAM

DOEpatents

Dimsdle, Jeffrey William [Overland Park, KS

2007-07-17

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Method of differential-phase/absolute-amplitude QAM

DOEpatents

Dimsdle, Jeffrey William

2007-10-02

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Treatment of oily port wastewater effluents using the ultraviolet/hydrogen peroxide photodecomposition system.

PubMed

Siedlecka, Ewa Maria; Stepnowski, Piotr

2006-08-01

This paper presents the nonselective degradation of mechanically pretreated oily wastewater by hydrogen peroxide (H2O2) in the presence and absence of UV irradiation. The effect of chemical oxidation on wastewater biodegradability was also examined. The exclusive use of H2O2 photolyzed by daylight results in quite efficient degradation rates for the low peroxide concentrations used. Higher hydrogen peroxide concentrations inhibit degradation of organic contaminants in the wastewater. The degradation rates of all contaminants are relatively high with an advanced oxidation system (UV/H2O2), but degradation efficiencies are not distinguishably different when 20 or 45 minutes of UV irradiation is used. The excess of H2O2 used in the process can inhibit phenolic degradation and may lead to the formation of a new phenolic fraction. The biodegradability of port wastewater did not increase significantly following the application of the advanced oxidation process.

Quantitating protein synthesis, degradation, and endogenous antigen processing.

PubMed

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

2003-03-01

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

Pd-MnO2 nanoparticles/TiO2 nanotube arrays (NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light.

PubMed

Thabit, Mohamed; Liu, Huiling; Zhang, Jian; Wang, Bing

2017-10-01

Pd-MnO 2 /TiO 2 nanotube arrays (NTAs) photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO 2 /TiO 2 NTAs photo electrodes were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet-visible diffuse reflectance spectrum (DRS); photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination (xenon light). The performed analyses illustrated that Pd-MnO 2 codoped particles were successfully deposited onto the surface of the TiO 2 nanotube arrays; DRS results showed significant improvement in visible light absorption which was between 400 and 700nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant (Rhodamine B) illustrated a superior photocatalytic (PC) efficiency of approximately 95% compared to the bare TiO 2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of OH radicals. Copyright © 2017. Published by Elsevier B.V.

Preparation of transition metal composite graphite felt cathode for efficient heterogeneous electro-Fenton process.

PubMed

Liang, Liang; Yu, Fangke; An, Yiran; Liu, Mengmeng; Zhou, Minghua

2017-01-01

A composite graphite felt (GF) modified with transition metal was fabricated and used as cathode in heterogeneous electro-Fenton (EF) for methyl orange (MO) degradation. Characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), the morphology and surface physicochemical properties of the cathodes after modification were observed considerably changed. After loading metals, the current response became higher, the accumulation of H 2 O 2 and the degradation efficiency of MO were improved. Under the same conditions, GF-Co had the highest catalytic activity for electro-reduction of O 2 to H 2 O 2 and MO degradation. At pH 3, 99 % of MO degradation efficiency was obtained using GF-Co after 120 min treatment and even at initial pH 9, 82 % of that was obtained. TOC removal efficiency reached 93.8 % using GF-Co at pH 3 after 120 min treatment while that was 12.3 % using GF. After ten-time runs, the mineralization ratio of the GF-Co was still 89.5 %, suggesting that GF-Co was very promising for wastewater treatment. The addition of isopropanol proved that · OH played an important role in degradation of MO.

Destroying lignocellulosic matters for enhancing methane production from excess sludge.

PubMed

Hao, Xiaodi; Hu, Yuansheng; Cao, Daqi

2016-01-01

A lot of lignocellulosic matters are usually present in excess sludge, which are hardly degraded in anaerobic digestion (AD) and thus remains mostly in digested sludge. This is a reason why the conversion rate of sludge organics into energy (CH4) is often low. Obviously, the hydrolysis of AD cannot destruct the structure of lignocellulosic matters. Structural destruction of lignocellulosic matters has to be performed in AD. In this study, pretreatments with the same principles as cell disintegration of sludge were applied to destruct lignocellulosic matters so that these materials could be converted to CH4 via AD. Acid, alkali, thermal treatment and ultrasonic were used in the experiments to observe the destructed/degraded efficiency of lignocellulosic matters. Thermal treatment was found to be the most effective pretreatment. Under optimized conditions (T = 150 °C and t = 30  min), pretreated sludge had a degraded rate of 52.6% in AD, due to easy destruction and/or degradation of hemicelluloses and celluloses in pretreatment. The sludge pretreated by thermal treatment could enhance the CH4 yield (mL CH4 g(-1) VSS) by 53.6% compared to raw sludge. Economically, the thermal treatment can balance the input energy with the produced energy (steam and electricity).

A comparison of organophosphate degradation genes and bioremediation applications.

PubMed

Iyer, Rupa; Iken, Brian; Damania, Ashish

2013-12-01

Organophosphates (OPs) form the bulk of pesticides that are currently in use around the world accounting for more than 30% of the world market. They also form the core for many nerve-based warfare agents including sarin and soman. The widespread use and the resultant build-up of OP pesticides and chemical nerve agents has led to the development of major health problems due to their extremely toxic interaction with any biological system that encounters them. Growing concern over the accumulation of OP compounds in our food products, in the soils from which they are harvested and in wastewater run-off has fuelled a growing interest in microbial biotechnology that provides cheap, efficient OP detoxification to supplement expensive chemical methods. In this article, we review the current state of knowledge of OP pesticide and chemical agent degradation and attempt to clarify confusion over identification and nomenclature of two major families of OP-degrading enzymes through a comparison of their structure and function. The isolation, characterization, utilization and manipulation of the major detoxifying enzymes and the molecular basis of degradation of OP pesticides and chemical nerve agents are discussed as well as the achievements and technological advancements made towards the bioremediation of such compounds. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Fe1-xZnxS ternary solid solution as an efficient Fenton-like catalyst for ultrafast degradation of phenol.

PubMed

Gao, Jing; Liu, Yutang; Xia, Xinnian; Wang, Longlu; Dong, Wanyue

2018-07-05

Heterogeneous Fenton-like system has been proved to be an promising alternative to Fenton system due to its easy separation. However, it's a challenge to design heterogeneous Fenton-like catalysts with high activity and great durability. Here, ternary solid solution Fe 1-x Zn x S were prepared via hydrothermal synthesis as heterogeneous Fenton-like catalysts. The Fe 0.7 Zn 0.3 S sample exhibited state of the art activity for yielding OH by H 2 O 2 decomposition, and the ultrafast degradation of phenol was achieved in 4 min at initial acidic condition under room temperature. The phenol degradation rate constant of Fe 0.7 Zn 0.3 S was 99 and 70 times of ZnS and FeS, respectively. Further, we show that the unique structural configuration of iron atoms, the formation of FeS 2 -pyrite with (200) plane, are responsible for the excellent activity. The intermediate products were identified by LC-MS and a possible pathway was accordingly proposed to elucidate the mechanism of phenol degradation by OH. Overall, this work provides an idea for the rational design of the relevant heterogeneous Fenton-like catalysts. Copyright © 2018 Elsevier B.V. All rights reserved.

Optimization of degradation of Reactive Black 5 (RB5) and electricity generation in solar photocatalytic fuel cell system.

PubMed

Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusoff, NikAthirah; Lee, Sin-Li; Yusuf, Sara Yasina

2017-10-01

The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their V oc , J sc and P max . The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biological treatment of thin-film transistor liquid crystal display (TFT-LCD) wastewater using aerobic and anoxic/oxic sequencing batch reactors.

PubMed

Lei, Chin-Nan; Whang, Liang-Ming; Chen, Po-Chun

2010-09-01

The amount of pollutants produced during manufacturing processes of thin-film transistor liquid crystal display (TFT-LCD) substantially increases due to an increasing production of the opto-electronic industry in Taiwan. This study presents the treatment performance of one aerobic and one anoxic/oxic (A/O) sequencing batch reactors (SBRs) treating synthetic TFT-LCD wastewater containing dimethyl sulfoxide (DMSO), monoethanolamine (MEA), and tetra-methyl ammonium hydroxide (TMAH). The long-term monitoring results for the aerobic and A/O SBRs demonstrate that stable biodegradation of DMSO, MEA, and TMAH can be achieved without any considerably adverse impacts. The ammonium released during MEA and TMAH degradation can also be completely oxidized to nitrate through nitrification in both SBRs. Batch studies on biodegradation rates for DMSO, MEA, and TMAH under anaerobic, anoxic, and aerobic conditions indicate that effective MEA degradation can be easily achieved under all three conditions examined, while efficient DMSO and TMAH degradation can be attained only under anaerobic and aerobic conditions, respectively. The potential odor problem caused by the formation of malodorous dimethyl sulfide from DMSO degradation under anaerobic conditions, however, requires insightful consideration in treating DMSO-containing wastewater. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Nicosulfuron Biodegradation by a Novel Cold-Adapted Strain Oceanisphaera psychrotolerans LAM-WHM-ZC.

PubMed

Zhou, Shan; Song, Jinlong; Dong, Weiwei; Mu, Yingchun; Zhang, Qi; Fan, Ziwen; Wang, Yanwei; Kong, Delong; Zhou, Yiqing; Jiang, Xu; Zhao, Bin; Han, Gang; Ruan, Zhiyong

2017-11-29

Nicosulfuron is a common environmental pollutant, posing a great threat to aquatic systems and causing significant damage to crops. This study reported a cold-adapted strain Oceanisphaera psychrotolerans LAM-WHM-ZC, which efficiently degrades nicosulfuron over a wide range of temperatures (5 to 40 °C). The Box-Behnken design method was used to optimize the degradation conditions. O. psychrotolerans LAM-WHM-ZC can degrade 92.4% and 74.6% of initially supplemented 100 mg/L nicosulfuron under the optimum and low temperature of 18.1 and 5 °C, respectively, within 7 days. O. psychrotolerans LAM-WHM-ZC was found to be highly efficient in degrading cinosulfuron, chlorsulfuron, rimsulfuron, bensulfuron methyl, and ethametsulfuron methyl. Metabolites from nicosulfuron degradation were identified by UPLC-MS, and a possible degradation pathway was proposed. Furthermore, O. psychrotolerans LAM-WHM-ZC can also degrade nicosulfuron in soil; 78.6% and 67.4% of the initial nicosulfuron supplemented at 50 mg/kg were removed at 18.1 and 5 °C, respectively, within 15 days.

Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

PubMed

Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

2014-11-01

Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

Degradation and decolorization of monosodium glutamate wastewater with Coriolus versicolor.

PubMed

Jia, Cuiying; Kang, Ruijuan; Zhang, Yuhui; Zhang, Yong; Cong, Wei

2007-10-01

Degradation and decolorization of monosodium glutamate wastewater (MSGW) with Coriolus versicolor were firstly carried out. The effects of various operation parameters namely wastewater concentrations, pH, culture time and incidence of sterilization on maximum percentage of degradation and decolorization of wastewater were investigated. Studies of mycelium and enzyme for C. versicolor degradation and decolorization were estimated in this study. Ten percentage of wastewater concentration and pH = 5.0 were found to be the most suitable ones among the other experiments. The highest degradation and decolorization efficiency of wastewater was obtained at the fifth day of cultivation, which was displayed with more than 70% chemical oxygen demand removal, 83% total sugar removal and 55% color removal, respectively. Sterile operation had no remarkable effect on the degradation and decolorization efficiency for C. versicolor. Mycelium and the extra cellular fungal enzyme were both necessary for the degradation and decolorization of MSGW. C. versicolor possesses great potential and economic advantages in MSGW treatment.

Degradation of imidacloprid in wastewater by dielectric barrier discharge system

NASA Astrophysics Data System (ADS)

Li, Kebin

2018-03-01

The degradation behavior of imidacloprid in wastewater was investigated with dielectric barrier discharge (DBD) system and the effect of several factors that could influence degradation process was explored in this study. The study showed that imidacloprid could be effectively removed by DBD system under certain conditions. The optimal removal efficiency was 75.6% when applied voltage was 75 V and 160 min was selected as the discharge time. Moreover, lower conductivity and alkaline environment were favorable for the imidacloprid degradation. The presence of Cu2+ and Fe2+ could benefit for the imidacloprid degradation, however the catalytic effect of Cu2+ was lower than that of Fe2+. Furthermore, methanol as scavenger decreased the removal efficiency of imidacloprid owing to the scavenger inhibited the generation of hydroxyl radicals during the DBD process.

Engineering Neprilysin Activity and Specificity to Create a Novel Therapeutic for Alzheimer’s Disease

PubMed Central

Webster, Carl I.; Burrell, Matthew; Olsson, Lise-Lotte; Fowler, Susan B.; Digby, Sarah; Sandercock, Alan; Snijder, Arjan; Tebbe, Jan; Haupts, Ulrich; Grudzinska, Joanna; Jermutus, Lutz; Andersson, Christin

2014-01-01

Neprilysin is a transmembrane zinc metallopeptidase that degrades a wide range of peptide substrates. It has received attention as a potential therapy for Alzheimer’s disease due to its ability to degrade the peptide amyloid beta. However, its broad range of peptide substrates has the potential to limit its therapeutic use due to degradation of additional peptides substrates that tightly regulate many physiological processes. We sought to generate a soluble version of the ectodomain of neprilysin with improved activity and specificity towards amyloid beta as a potential therapeutic for Alzheimer’s disease. Extensive amino acid substitutions were performed at positions surrounding the active site and inner surface of the enzyme and variants screened for activity on amyloid beta 1–40, 1–42 and a variety of other physiologically relevant peptides. We identified several mutations that modulated and improved both enzyme selectivity and intrinsic activity. Neprilysin variant G399V/G714K displayed an approximately 20-fold improved activity on amyloid beta 1–40 and up to a 3,200-fold reduction in activity on other peptides. Along with the altered peptide substrate specificity, the mutant enzyme produced a markedly altered series of amyloid beta cleavage products compared to the wild-type enzyme. Crystallisation of the mutant enzyme revealed that the amino acid substitutions result in alteration of the shape and size of the pocket containing the active site compared to the wild-type enzyme. The mutant enzyme offers the potential for the more efficient degradation of amyloid beta in vivo as a therapeutic for the treatment of Alzheimer’s disease. PMID:25089527

Nano-based sensor for assessment of weaponry structural degradation

NASA Astrophysics Data System (ADS)

Brantley, Christina L.; Edwards, Eugene; Ruffin, Paul B.; Kranz, Michael

2016-04-01

Missiles and weaponry-based systems are composed of metal structures that can degrade after prolonged exposure to environmental elements. A particular concern is accumulation of corrosion that generally results from prolonged environmental exposure. Corrosion, defined as the unintended destruction or deterioration of a material due to its interaction with the environment, can negatively affect both equipment and infrastructure. System readiness and safety can be reduced if corrosion is not detected, prevented and managed. The current corrosion recognition methods (Visual, Radiography, Ultrasonics, Eddy Current, and Thermography) are expensive and potentially unreliable. Visual perception is the most commonly used method for determining corrosion in metal. Utilization of an inductance-based sensor system is being proposed as part of the authors' research. Results from this research will provide a more efficient, economical, and non-destructive sensing approach. Preliminary results demonstrate a highly linear degradation within a corrosive environment due to the increased surface area available on the sensor coupon. The inductance of the devices, which represents a volume property of the coupon, demonstrated sensitivity to corrosion levels. The proposed approach allows a direct mass-loss measurement based on the change in the inductance of the coupon when placed in an alternating magnetic field. Prototype devices have demonstrated highly predictable corrosion rates that are easily measured using low-power small electronic circuits and energy harvesting methods to interrogate the sensor. Preliminary testing demonstrates that the device concept is acceptable and future opportunities for use in low power embedded applications are achievable. Key results in this paper include the assessment of typical Army corrosion cost, degradation patterns of varying metal materials, and application of wireless sensors elements.

Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

NASA Astrophysics Data System (ADS)

Makama, A. B.; Salmiaton, A.; Saion, E. B.; Choong, T. S. Y.; Abdullah, N.

2016-07-01

Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl2 and Na2S) in the presence of fixed amount of ZnCO3 nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-Ct/C0) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

Rapid, Efficient and Versatile Strategies for Functionally Sophisticated Polymers and Nanoparticles: Degradable Polyphosphoesters and Anisotropic Distribution of Chemical Functionalities

NASA Astrophysics Data System (ADS)

Zhang, Shiyi

The overall emphasis of this dissertation research included two kinds of asymmetrically-functionalized nanoparticles with anisotropic distributions of chemical functionalities, three degradable polymers synthesized by organocatalyzed ring-opening polymerizations, and two polyphosphoester-based nanoparticle systems for various biomedical applications. Inspired by the many hierarchical assembly processes that afford complex materials in Nature, the construction of asymmetrically-functionalized nanoparticles with efficient surface chemistries and the directional organization of those building blocks into complex structures have attracted much attention. The first method generated a Janus-faced polymer nanoparticle that presented two orthogonally click-reactive surface chemistries, thiol and azido. This robust method involved reactive functional group transfer by templating against gold nanoparticle substrates. The second method produced nanoparticles with sandwich-like distribution of crown ether functionalities through a stepwise self-assembly process that utilized crown ether-ammonium supramolecular interactions to mediate inter-particle association and the local intra-particle phase separation of unlike hydrophobic polymers. With the goal to improve the efficiency of the production of degradable polymers with tunable chemical and physical properties, a new type of reactive polyphosphoester was synthesized bearing alkynyl groups by an organocatalyzed ring-opening polymerization, the chemical availability of the alkyne groups was investigated by employing "click" type azide-alkyne Huisgen cycloaddition and thiol-yne radical-mediated reactions. Based on this alkyne-functionalized polyphosphoester polymer and its two available "click" type reactions, two degradable nanoparticle systems were developed. To develop the first system, the well defined poly(ethylene oxide)-block-polyphosphester diblock copolymer was transformed into a multifunctional Paclitaxel drug conjugate by densely attaching the polyphosphoester block with azide-functionalized Paclitaxel by azide-alkyne Huisgen cycloaddition. This Paclitaxel drug conjugate provides a powerful platform for combinational cancer therapy and bioimaging due to its ultra-high Paclitaxel loading (> 65 wt%), high water solubility (>6.2 mg/mL for PTX) and easy functionalization. Another polyphosphoester-based nanoparticle system has been developed by a programmable process for the rapid and facile preparation of a family of nanoparticles with different surface charges and functionalities. The non-ionic, anionic, cationic and zwitterionic nanoparticles with hydrodynamic diameters between 13 nm to 21 nm and great size uniformity could be rapidly prepared from small molecules in 6 h or 2 days. The anionic and zwitterionic nanoparticles were designed to load silver ions to treat pulmonary infections, while the cationic nanoparticles are being applied to regulate lung injuries by serving as a degradable iNOS inhibitor conjugates. In addition, a direct synthesis of acid-labile polyphosphoramidate by organobase-catalyzed ring-opening polymerization and an improved two-step preparation of polyphosphoester ionomer by acid-assisted cleavage of phosphoramidate bonds on polyphosphoramidate were developed. Polyphosphoramidate and polyphosphoester ionomers may be applied to many applications, due to their unique chemical and physical properties.

Comparison of the protection effectiveness of acrylic polyurethane coatings containing bark extracts on three heat-treated North American wood species: Surface degradation

NASA Astrophysics Data System (ADS)

Kocaefe, Duygu; Saha, Sudeshna

2012-04-01

High temperature heat-treatment of wood is a very valuable technique which improves many properties (biological durability, dimensional stability, thermal insulating characteristics) of natural wood. Also, it changes the natural color of wood to a very attractive dark brown color. Unfortunately, this color is not stable if left unprotected in external environment and turns to gray or white depending on the wood species. To overcome this problem, acrylic polyurethane coatings are applied on heat-treated wood to delay surface degradations (color change, loss of gloss, and chemical modifications) during aging. The acrylic polyurethane coatings which have high resistance against aging are further modified by adding bark extracts and/or lignin stabilizer to enhance their effectiveness in preventing the wood aging behavior. The aging characteristic of this coating is compared with acrylic polyurethane combined with commercially available organic UV stabilizers. In this study, their performance on three heat-treated North American wood species (jack pine, quaking aspen and white birch) are compared under accelerated aging conditions. Both the color change data and visual assessment indicate improvement in protective characteristic of acrylic polyurethane when bark extracts and lignin stabilizer are used in place of commercially available UV stabilizer. The results showed that although acrylic polyurethane with bark extracts and lignin stabilizer was more efficient compared to acrylic polyurethane with organic UV stabilizers in protecting heat-treated jack pine, it failed to protect heat-treated aspen and birch effectively after 672 h of accelerated aging. This degradation was not due to the coating adhesion loss or coating degradation during accelerated aging; rather, it was due to the significant degradation of heat-treated aspen and birch surface beneath this coating. The XPS results revealed formation of carbonyl photoproducts after aging on the coated surfaces and chain scission of Csbnd N of urethane linkages.

Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community.

PubMed

Lezcano, María Ángeles; Morón-López, Jesús; Agha, Ramsy; López-Heras, Isabel; Nozal, Leonor; Quesada, Antonio; El-Shehawy, Rehab

2016-11-03

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlr A gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlr A gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr ⁺ and mlr - bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains ( Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection ( Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr ⁺ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr - strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non- mlr microcystin degradation pathways. Considering the abundance of the mlr - bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non- mlr degradation pathways deserves special attention.

Synergistic rhizosphere degradation of γ-hexachlorocyclohexane (lindane) through the combinatorial plant-fungal action.

PubMed

Asemoloye, Michael Dare; Ahmad, Rafiq; Jonathan, Segun Gbolagade

2017-01-01

Fungi are usually involved in degradation/deterioration of many anthropogenic wastes due to their verse enzyme secretions and adaptive capabilities. In this study, five dominant fungal strains were isolated from an aged lindane polluted site, they were all mixed (100 mg each) together with pent mushroom compost (SMC) and applied to lindane polluted soil (5 kg) at 10, 20, 30, 40% and control 0% (soil with no treatment), these were used to grow M. maximus Jacq for 3 months. To establish lindane degradation, deductions such as Degradation rate (K1), Half-life (t1/2) and Degradation efficiency (DE) were made based on the analyzed lindane concentrations before and after the experiment. We also tested the presence and expressions of phosphoesterases (mpd and opd-A) and catechol 1,2-dioxygenases (efk2 and efk4) genes in the strains. The stains were identified as Aspergillus niger (KY693970); Talaromyces atroroseus (KY488464), Talaromyces purpurogenus (KY488468), Yarrowia lipolytica (KY488469) and Aspergillus flavus (KY693973) through morphological and molecular methods. Combined rhizospheric action of M. maximus and fungi speed up lindane degradation rate, initially detected lindane concentration of 45 mg/kg was reduced to 11.26, 9.34 and 11.23 mg/kg in 20, 30 and 40% treatments respectively making 79.76, 85.93 and 88.67% degradation efficiencies. K1 of 1.29 was recorded in control while higher K1 of 1.60, 1.96 and 2.18 /day were recorded in 20, 30 and 40% treatments respectively. The best t1/2 of 0.32 and 0.35 /day were recorded in 40 and 30% compared to control (0.54 /day). All the strains were also affirmed to possess the tested genes; opd was overexpressed in all the strains except KY693973 while mpd was overexpressed in KY693970, KY488464 but moderately expressed in KY488468, KY488469 and KY693973. However, efk genes were under-expressed in most of the strains except KY488469 and KY693973 which showed moderate expression of efk4. This work suggests that the synergistic association of the identified rhizospheric fungi and M. maximus roots could be used to remove lindane in soil at a limited time period and this combination could be used at large scale.

Synergistic rhizosphere degradation of γ-hexachlorocyclohexane (lindane) through the combinatorial plant-fungal action

PubMed Central

Ahmad, Rafiq; Jonathan, Segun Gbolagade

2017-01-01

Fungi are usually involved in degradation/deterioration of many anthropogenic wastes due to their verse enzyme secretions and adaptive capabilities. In this study, five dominant fungal strains were isolated from an aged lindane polluted site, they were all mixed (100 mg each) together with pent mushroom compost (SMC) and applied to lindane polluted soil (5 kg) at 10, 20, 30, 40% and control 0% (soil with no treatment), these were used to grow M. maximus Jacq for 3 months. To establish lindane degradation, deductions such as Degradation rate (K1), Half-life (t1/2) and Degradation efficiency (DE) were made based on the analyzed lindane concentrations before and after the experiment. We also tested the presence and expressions of phosphoesterases (mpd and opd-A) and catechol 1,2-dioxygenases (efk2 and efk4) genes in the strains. The stains were identified as Aspergillus niger (KY693970); Talaromyces atroroseus (KY488464), Talaromyces purpurogenus (KY488468), Yarrowia lipolytica (KY488469) and Aspergillus flavus (KY693973) through morphological and molecular methods. Combined rhizospheric action of M. maximus and fungi speed up lindane degradation rate, initially detected lindane concentration of 45 mg/kg was reduced to 11.26, 9.34 and 11.23 mg/kg in 20, 30 and 40% treatments respectively making 79.76, 85.93 and 88.67% degradation efficiencies. K1 of 1.29 was recorded in control while higher K1 of 1.60, 1.96 and 2.18 /day were recorded in 20, 30 and 40% treatments respectively. The best t1/2 of 0.32 and 0.35 /day were recorded in 40 and 30% compared to control (0.54 /day). All the strains were also affirmed to possess the tested genes; opd was overexpressed in all the strains except KY693973 while mpd was overexpressed in KY693970, KY488464 but moderately expressed in KY488468, KY488469 and KY693973. However, efk genes were under-expressed in most of the strains except KY488469 and KY693973 which showed moderate expression of efk4. This work suggests that the synergistic association of the identified rhizospheric fungi and M. maximus roots could be used to remove lindane in soil at a limited time period and this combination could be used at large scale. PMID:28859100

Construction of RGO/CdIn2S4/g-C3N4 ternary hybrid with enhanced photocatalytic activity for the degradation of tetracycline hydrochloride

NASA Astrophysics Data System (ADS)

Xiao, Peng; Jiang, Deli; Ju, Lixin; Jing, Junjie; Chen, Min

2018-03-01

Although RGO shows great advantage in promoting charge separation and transfer of semiconductor, construction of an efficient RGO-incorporated photocatalyst is still challenging. Herein, RGO was employed to construct novel RGO/CdIn2S4/g-C3N4 (donated as RGO/CIS/CN) ternary photocatalyst by a facile hydrothermal method for the degradation of tetracycline hydrochloride (TC). The RGO/CIS/CN ternary photocatalyst showed significantly enhanced photocatalytic activity towards the degradation of TC as compared to the binary CIS/CN, CIS/CN, and CN/RGO. The photoluminescence and photocurrent response results indicate that this enhanced photocatalytic activity can be mainly ascribed to the improved charge separation and transfer efficiency. Based on the radical trapping and electron spin resonance results, the superoxide radicals and holes are proposed to play an important role in the degradation of TC over RGO/CIS/CN ternary photocatalyst. This work paves new opportunities for the synthesis of RGO-incorporated ternary photocatalyst as an efficient photocatalyst for the degradation of organic contaminant.

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

NASA Astrophysics Data System (ADS)

Li, Xiaojuan; Jin, Bo; Huang, Jingwen; Zhang, Qingchun; Peng, Rufang; Chu, Shijin

2018-06-01

In this study, novel ternary Fe2O3/ZnO/ZnFe2O4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.

Bioremediation of hydrocarbon degradation in a petroleum-contaminated soil and microbial population and activity determination.

PubMed

Wu, Manli; Li, Wei; Dick, Warren A; Ye, Xiqiong; Chen, Kaili; Kost, David; Chen, Liming

2017-02-01

Bioremediation of hydrocarbon degradation in petroleum-polluted soil is carried out by various microorganisms. However, little information is available for the relationships between hydrocarbon degradation rates in petroleum-contaminated soil and microbial population and activity in laboratory assay. In a microcosm study, degradation rate and efficiency of total petroleum hydrocarbons (TPH), alkanes, and polycyclic aromatic hydrocarbons (PAH) in a petroleum-contaminated soil were determined using an infrared photometer oil content analyzer and a gas chromatography mass spectrometry (GC-MS). Also, the populations of TPH, alkane, and PAH degraders were enumerated by a modified most probable number (MPN) procedure, and the hydrocarbon degrading activities of these degraders were determined by the Biolog (MT2) MicroPlates assay. Results showed linear correlations between the TPH and alkane degradation rates and the population and activity increases of TPH and alkane degraders, but no correlation was observed between the PAH degradation rates and the PAH population and activity increases. Petroleum hydrocarbon degrading microbial population measured by MPN was significantly correlated with metabolic activity in the Biolog assay. The results suggest that the MPN procedure and the Biolog assay are efficient methods for assessing the rates of TPH and alkane, but not PAH, bioremediation in oil-contaminated soil in laboratory. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification and mitigation of narrow spectral artifacts that degrade searches for persistent gravitational waves in the first two observing runs of Advanced LIGO

NASA Astrophysics Data System (ADS)

Covas, P. B.; Effler, A.; Goetz, E.; Meyers, P. M.; Neunzert, A.; Oliver, M.; Pearlstone, B. L.; Roma, V. J.; Schofield, R. M. S.; Adya, V. B.; Astone, P.; Biscoveanu, S.; Callister, T. A.; Christensen, N.; Colla, A.; Coughlin, E.; Coughlin, M. W.; Crowder, S. G.; Dwyer, S. E.; Eggenstein, H.-B.; Hourihane, S.; Kandhasamy, S.; Liu, W.; Lundgren, A. P.; Matas, A.; McCarthy, R.; McIver, J.; Mendell, G.; Ormiston, R.; Palomba, C.; Papa, M. A.; Piccinni, O. J.; Rao, K.; Riles, K.; Sammut, L.; Schlassa, S.; Sigg, D.; Strauss, N.; Tao, D.; Thorne, K. A.; Thrane, E.; Trembath-Reichert, S.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Adams, C.; Adhikari, R. X.; Ananyeva, A.; Appert, S.; Arai, K.; Aston, S. M.; Austin, C.; Ballmer, S. W.; Barker, D.; Barr, B.; Barsotti, L.; Bartlett, J.; Bartos, I.; Batch, J. C.; Bejger, M.; Bell, A. S.; Betzwieser, J.; Billingsley, G.; Birch, J.; Biscans, S.; Biwer, C.; Blair, C. D.; Blair, R. M.; Bork, R.; Brooks, A. F.; Cao, H.; Ciani, G.; Clara, F.; Clearwater, P.; Cooper, S. J.; Corban, P.; Countryman, S. T.; Cowart, M. J.; Coyne, D. C.; Cumming, A.; Cunningham, L.; Danzmann, K.; Costa, C. F. Da Silva; Daw, E. J.; DeBra, D.; DeRosa, R. T.; DeSalvo, R.; Dooley, K. L.; Doravari, S.; Driggers, J. C.; Edo, T. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fair, H.; Galiana, A. Fernández; Ferreira, E. C.; Fisher, R. P.; Fong, H.; Frey, R.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gateley, B.; Giaime, J. A.; Giardina, K. D.; Goetz, R.; Goncharov, B.; Gras, S.; Gray, C.; Grote, H.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, E. D.; Hammond, G.; Hanks, J.; Hanson, J.; Hardwick, T.; Harry, G. M.; Heintze, M. C.; Heptonstall, A. W.; Hough, J.; Inta, R.; Izumi, K.; Jones, R.; Karki, S.; Kasprzack, M.; Kaufer, S.; Kawabe, K.; Kennedy, R.; Kijbunchoo, N.; Kim, W.; King, E. J.; King, P. J.; Kissel, J. S.; Korth, W. Z.; Kuehn, G.; Landry, M.; Lantz, B.; Laxen, M.; Liu, J.; Lockerbie, N. A.; Lormand, M.; MacInnis, M.; Macleod, D. M.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Marsh, P.; Martin, I. W.; Martynov, D. V.; Mason, K.; Massinger, T. J.; Matichard, F.; Mavalvala, N.; McClelland, D. E.; McCormick, S.; McCuller, L.; McIntyre, G.; McRae, T.; Merilh, E. L.; Miller, J.; Mittleman, R.; Mo, G.; Mogushi, K.; Moraru, D.; Moreno, G.; Mueller, G.; Mukund, N.; Mullavey, A.; Munch, J.; Nelson, T. J. N.; Nguyen, P.; Nuttall, L. K.; Oberling, J.; Oktavia, O.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ottaway, D. J.; Overmier, H.; Palamos, J. R.; Parker, W.; Pele, A.; Penn, S.; Perez, C. J.; Phelps, M.; Pierro, V.; Pinto, I.; Principe, M.; Prokhorov, L. G.; Puncken, O.; Quetschke, V.; Quintero, E. A.; Radkins, H.; Raffai, P.; Ramirez, K. E.; Reid, S.; Reitze, D. H.; Robertson, N. A.; Rollins, J. G.; Romel, C. L.; Romie, J. H.; Ross, M. P.; Rowan, S.; Ryan, K.; Sadecki, T.; Sanchez, E. J.; Sanchez, L. E.; Sandberg, V.; Savage, R. L.; Sellers, D.; Shaddock, D. A.; Shaffer, T. J.; Shapiro, B.; Shoemaker, D. H.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Sorazu, B.; Spencer, A. P.; Staley, A.; Strain, K. A.; Sun, L.; Tanner, D. B.; Tasson, J. D.; Taylor, R.; Thomas, M.; Thomas, P.; Toland, K.; Torrie, C. I.; Traylor, G.; Tse, M.; Tuyenbayev, D.; Vajente, G.; Valdes, G.; van Veggel, A. A.; Vecchio, A.; Veitch, P. J.; Venkateswara, K.; Vo, T.; Vorvick, C.; Wade, M.; Walker, M.; Ward, R. L.; Warner, J.; Weaver, B.; Weiss, R.; Weßels, P.; Willke, B.; Wipf, C. C.; Wofford, J.; Worden, J.; Yamamoto, H.; Yancey, C. C.; Yu, Hang; Yu, Haocun; Zhang, L.; Zhu, S.; Zucker, M. E.; Zweizig, J.; LSC Instrument Authors

2018-04-01

Searches are under way in Advanced LIGO and Virgo data for persistent gravitational waves from continuous sources, e.g. rapidly rotating galactic neutron stars, and stochastic sources, e.g. relic gravitational waves from the Big Bang or superposition of distant astrophysical events such as mergers of black holes or neutron stars. These searches can be degraded by the presence of narrow spectral artifacts (lines) due to instrumental or environmental disturbances. We describe a variety of methods used for finding, identifying and mitigating these artifacts, illustrated with particular examples. Results are provided in the form of lists of line artifacts that can safely be treated as non-astrophysical. Such lists are used to improve the efficiencies and sensitivities of continuous and stochastic gravitational wave searches by allowing vetoes of false outliers and permitting data cleaning.

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

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

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

Antioxidant activity from encapsulated Cinnamaldehyde-Chitosan

NASA Astrophysics Data System (ADS)

Ariestiani, Bonita; Purbowatingrum; Ngadiwiyana; Ismiyarto; Fachriyah, Enny; Nurani, Khikmah

2018-05-01

Cinnamaldehyde compound is a powerful antioxidant agent that can effectively combat the free radicals referred to superoxide anions and hydroxy radicals, as well as other free radicals in in vitro testing. An antioxidant is an electron donor or reductant. antioxidants are also compounds that can inhibit oxidation reactions by binding to free radicals and highly reactive molecules. As a result, cell damage will be inhibited. However, the use of this compound still provides unsatisfactory results due to its degradation during the absorption process. The solution offered to solve the problem is by encapsulated it within chitosan nanoparticles that serve to protect the bioactive compound from degradation, increases of solubility and delivery of a bioactive compound to the target site by using freeze-drying technique. The value of encapsulation efficiency (EE) of cinnamaldyhde which encapsulated within chitosan nanoparticles is about 74,389% also antioxidant activity test showed that cinnamaldehyde encapsulated by nanochitosan could inhibit free radicals of 223.44 in IC50.

Factors and processes modulating phenotypes in neuronopathic lysosomal storage diseases.

PubMed

Jakóbkiewicz-Banecka, Joanna; Gabig-Cimińska, Magdalena; Banecka-Majkutewicz, Zyta; Banecki, Bogdan; Węgrzyn, Alicja; Węgrzyn, Grzegorz

2014-03-01

Lysosomal storage diseases are inherited metabolic disorders caused by genetic defects causing deficiency of various lysosomal proteins, and resultant accumulation of non-degraded compounds. They are multisystemic diseases, and in most of them (>70%) severe brain dysfunctions are evident. However, expression of various phenotypes in particular diseases is extremely variable, from non-neuronopathic to severely neurodegenerative in the deficiency of the same enzyme. Although all lysosomal storage diseases are monogenic, clear genotype-phenotype correlations occur only in some cases. In this article, we present an overview on various factors and processes, both general and specific for certain disorders, that can significantly modulate expression of phenotypes in these diseases. On the basis of recent reports describing studies on both animal models and clinical data, we propose a hypothesis that efficiency of production of compounds that cannot be degraded due to enzyme deficiency might be especially important in modulation of phenotypes of patients suffering from lysosomal storage diseases.

Detection of some volatile degradation products released during photoexposition of ranitidine in a solid state.

PubMed

Jamrógiewicz, Marzena; Wielgomas, Bartosz

2013-03-25

Ranitidine (RAN) is on top of the list of prescribed drugs, due to its popularity as a selective H2-receptor antagonist, which efficiently decreases the amount of acid produced in the stomach. RAN is not stable both in a solid state and in a solution, which creates manufacturing problems, requires appropriate storage conditions, and results in a short drug shelf-life. The aim of this work was to study the emission of volatile degradation products generated during photoexposition of ranitidine hydrochloride in a solid state. Significant changes in volatile profile of irradiated RAN were detected using HS-SPME-GC-MS. Sixteen major peaks were noticed on the chromatograms of irradiated ranitidine and the structures of some compounds were elucidated, while the presence of acetaldoxime, thiazole, dimethylformamide, dimethylacetamide and 5-methylfurfural was confirmed by means of the analysis of the authentic standards. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaluation of the effect of organic pro-degradant concentration in polypropylene exposed to the natural ageing

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

Montagna, L. S., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Catto, A. L., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Rossini, K., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br

The production and consumption of plastics in the last decade has recorded a remarkable increase in the scientific and industrial interest in environmentally degradable polymer (EDPs). Polymers wastes are deposited improperly, such as dumps, landfills, rivers and seas, causing a serious problem by the accumulation in the environment. The abiotic processes, like the photodegradation, are the most efficient occurring in the open environmental, where the polymers undergo degradation from the action of sunlight that result from direct exposure to solar radiation, however depend of the type of chemical ageing, which is the principal component of climatic ageing. The subject ofmore » this work is to study the influence of concentration of organic pro-degradant (1, 2 and 3 % w/w) in the polypropylene (PP) exposed in natural ageing. PP samples with and without the additive were processed in plates square form, obtained by thermal compression molding (TCM) using a press at 200°C under 2 tons for 5 min, and then were exposed at natural ageing during 120 days. The presence of organic additive influenced on PP degradability, this fact was assessed by changes in the thermal and morphology properties of the samples after 120 days of natural ageing. Scanning Electronic Microscopy (SEM) results of the morphological surface of the modified PP samples showed greater degradation photochemical oxidative when compared to neat PP, due to increase of rugosity and formation of microvoids. PP samples with different pro-degradant concentration under natural ageing presented a degree of crystallinity, obtained by Differential Scanning Calorimeter (DSC) increases in comparing the neat PP.« less

Insight into synergistically enhanced adsorption and visible light photocatalytic performance of Z-scheme heterojunction of SrTiO3(La,Cr)-decorated WO3 nanosheets

NASA Astrophysics Data System (ADS)

Liu, Xin; Jiang, Junzhe; Jia, Yushuai; Qiu, Jinmin; Xia, Tonglin; Zhang, Yuhong; Li, Yuqin; Chen, Xiangshu

2017-08-01

The efficient treatment of dye wastewater has been a hot topic of environment field. The integration of adsorption and photocatalytic degradation via fabrication of bi-component heterojunction photocatalyst is considered as a facile and effective strategy to enhance the dye elimination efficiency. In this report, a Z-scheme heterojunction material, SrTiO3(La,Cr)/WO3 with bifunction of adsorption and photocatalysis was successfully synthesized for efficient removal of methylene blue (MB) under visible light irradiation. The morphology and microstructure characterization demonstrates that the SrTiO3(La,Cr) nanoparticles are uniformly decorated on the WO3 nanosheets, forming an intimate heterojunction interface. MB degradation results indicate that the removal efficiency by the synergistic adsorption-photocatalysis process is greatly improved compared to pure WO3 and SrTiO3(La,Cr) with the adsorption and photocatalytic activity closely related to the composition of the material. The possible mechanism for the enhanced photocatalytic activity could be ascribed to the formation of a Z-scheme heterojunction system based on active species trapping experiments. Furthermore, the investigations of adsorption kinetics and isotherm show that the adsorption process follows pseudo-second-order kinetic model and Langmuir isotherm, respectively. Due to the synergistic advantages of negative zeta potential, large surface area and accelerated separation of photogenerated carriers driven by Z-scheme heterojunction, SrTiO3(La,Cr)/WO3 exhibits excellent adsorption-photocatalytic performance and stability on MB removal, which could be potentially used for practical wastewater treatment.

Evaluation of degradation of antibiotic tetracycline in pig manure by electron beam irradiation.

PubMed

Cho, Jae-Young

2010-04-01

This study was carried out to evaluate the degradation efficiency and intermediate products of the tetracycline from artificially contaminated pig manure using of electron beam irradiation as a function of the absorbed dose. The degradation efficiency of tetracycline was 42.77% at 1 kGy, 64.20% at 3 kGy, 77.83% at 5 kGy, and 90.50% at 10 kGy. The initial concentration of tetracycline (300 mg kg(-1)) in pig manure decreased significantly to 24.2 +/- 5.3 mg kg(-1) after electron beam irradiation at 10 kGy. The radiolytic degradation products of tetracycline were 1,4-benzenedicarboxylic acid, hexadecanoic acid, 9-octadecenamide, 11-octadecenamide, and octadecanoic acid.

Photocatalytic degradation properties of V-doped TiO2 to automobile exhaust.

PubMed

Wang, Tong; Shen, Dongya; Xu, Tao; Jiang, Ruiling

2017-05-15

To improve the photocatalytic degradation properties of titanium dioxide (TiO 2 ) used as raw materials for purifying automobile exhaust (AE), the vanadium (V)-doped TiO 2 samples were prepared. The photocatalytic degradation efficiencies of V-doped TiO 2 to each component in AE were evaluated under ultraviolet (UV) and visible light irradiation, respectively. Results indicated that the photocatalytic activity of V-doped TiO 2 to AE was higher than that of pure TiO 2 , and the optimal V dopant content of TiO 2 was 1.0% under UV light irradiation. The degradation efficiencies of V-doped TiO 2 to NOx and HC were higher than those to CO 2 and CO in AE because of the reversible reaction between CO 2 and CO. In addition, it was found that the photocatalytic degradation efficiencies of V-doped TiO 2 to each component in AE were also increased under visible light irradiation. The V-doped TiO 2 also showed higher degradation efficiencies to NOx and HC than those to CO 2 and CO under visible light irradiation. The V doped TiO 2 presented higher photocatalytic activity to CO 2 than that to CO, but the reversible reaction between CO and CO 2 was not found under visible light irradiation. The photocatalytic reactions of pure and V-doped TiO 2 samples to each component in AE followed the first order kinetic pathway under the two light irradiations. It is concluded that the V doping is a feasible method to improve the photocatalytic degradation properties of TiO 2 to AE for air purification, developing a sustainable environmental purification technology based on TiO 2 materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation into adsorption and photocatalytic degradation of gaseous benzene in an annular fluidized bed photocatalytic reactor.

PubMed

Geng, Qijin; Tang, Shankang; Wang, Lintong; Zhang, Yunchen

2015-01-01

The adsorption and photocatalytic degradation of gaseous benzene were investigated considering the operating variables and kinetic mechanism using nano-titania agglomerates in an annular fluidized bed photocatalytic reactor (AFBPR) designed. The special adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of benzene were determined by linear regression analysis at various gas velocities and relative humidities (RH). Based on a series of photocatalytic degradation kinetic equations, the influences of operating variables on degradation efficiency, apparent reaction rate coefficient and half-life were explored. The findings indicated that the operating variables have obviously influenced the adsorption/photocatalytic degradation and corresponding kinetic parameters. In the photocatalytic degradation process, the relationship between photocatalytic degradation efficiency and RH indicated that water molecules have a dual-function which was related to the structure characteristics of benzene. The optimal operating conditions for photocatalytic degradation of gaseous benzene in AFBPR were determined as the fluidization number at 1.9 and RH required related to benzene concentration. This investigation highlights the importance of controlling RH and benzene concentration in order to obtain the desired synergy effect in photocatalytic degradation processes.

Chitosan layered gold nanorods as synergistic therapeutics for photothermal ablation and gene silencing in triple-negative breast cancer.

PubMed

Yang, Zhizhou; Liu, Tengfei; Xie, Yan; Sun, Zhaorui; Liu, Hongmei; Lin, Jinfeng; Liu, Changjing; Mao, Zong-Wan; Nie, Shinan

2015-10-01

Small interfering RNAs (siRNAs) are extensively studied due to their promising potential as therapeutic agents for a wide variety of diseases, including cancer. However, efficient delivery of siRNAs to target cells and tissues is problematic due to a lack of suitable delivery vehicles. In this work, we developed a layer-by-layer assembled chitosan-gold nanorods (Chit-Au NRs) siRNA delivery system to overcome biological barriers upon systemic injection. This platform was able to protect siRNAs form degradation upon exposure to ribonuclease (RNase) or serum. Confocal and intravital microscopy reveals that Chit-Au NRs/siRNAs are successfully delivered into target cells and tissue, and can efficiently escape from endosomal/lysosomal structures. Furthermore, Chit-Au NRs/siRNA were found to accumulate in high levels in tumor tissue. The delivery system was able to inhibit the oncogene expression (pyruvate kinase isozymeM2, PKM2) in MDA-MB-231 triple negative breast cancer cells, resulting in suppression of cell proliferation and migration. Moreover, the anticancer efficacy was further enhanced through NR-mediated photothermal ablation. In conclusion, the synergistic therapeutic properties of Chit-Au NRs/siRNA enable effective suppression of cancer growth. Small interfering RNA (siRNA) therapy has promising therapeutic applications, since the expression of any protein can be suppressed. However the successful implementation of siRNA has been challenging, due to rapid degradation, poor intracellular uptake and insufficient endosomal escape. Here, we have developed a gold nanorod/chitosan-based delivery vehicle for siRNA therapy. This platform successfully overcomes the afore-mentioned challenges and can simultaneously be used for photothermal therapy, due to the optical properties of gold nanorods. We show that the anticancer activity is dramatically improved by combining thermal therapy with gene silencing. Furthermore, the Au NRs carrier shows high accumulation in tumor tissue and high transfection efficiency. This manuscript has been reviewed and approved by all co-authors. The research has not been disclosed or published and is not under consideration for publication elsewhere. We would appreciate if the manuscript could be reviewed and considered for publication in Acta BIOMATERIALIA. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An Experimental Framework for Executing Applications in Dynamic Grid Environments

NASA Technical Reports Server (NTRS)

Huedo, Eduardo; Montero, Ruben S.; Llorente, Ignacio M.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

The Grid opens up opportunities for resource-starved scientists and engineers to harness highly distributed computing resources. A number of Grid middleware projects are currently available to support the simultaneous exploitation of heterogeneous resources distributed in different administrative domains. However, efficient job submission and management continue being far from accessible to ordinary scientists and engineers due to the dynamic and complex nature of the Grid. This report describes a new Globus framework that allows an easier and more efficient execution of jobs in a 'submit and forget' fashion. Adaptation to dynamic Grid conditions is achieved by supporting automatic application migration following performance degradation, 'better' resource discovery, requirement change, owner decision or remote resource failure. The report also includes experimental results of the behavior of our framework on the TRGP testbed.

Activation of peroxydisulfate by gas-liquid pulsed discharge plasma to enhance the degradation of p-nitrophenol

NASA Astrophysics Data System (ADS)

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

2017-06-01

Pulsed discharge in water and over water surfaces generates ultraviolet radiation, local high temperature, shock waves, and chemical reactive species, including hydroxyl radicals, hydrogen peroxide, and ozone. Pulsed discharge plasma (PDP) can oxidize and mineralize pollutants very efficiently, but high energy consumption restricts its application for industrial wastewater treatment. A novel method for improving the energy efficiency of wastewater treatment by PDP was proposed, in which peroxydisulfate (PDS) was added to wastewater and PDS was activated by PDP to produce more strong oxidizing radicals, including sulfate radicals and hydroxyl radicals, leading to a higher oxidation capacity for the PDP system. The experimental results show that the increase in solution conductivity slightly decreased the discharge power of the pulse discharge over the water surface. An increase in the discharge intensity improved the activation of PDS and therefore the degradation efficiency and energy efficiency of p-nitrophenol (PNP). An increase in the addition dosage of PDS greatly facilitated the degradation of PNP at a molar ratio of PDS to PNP of lower than 80:1, but the performance enhancement was no longer obvious at a dosage of more than 80:1. Under an applied voltage of 20 kV and a gas discharge gap of 2 mm, the degradation efficiency and energy efficiency of the PNP reached 90.7% and 45.0 mg kWh-1 for the plasma/PDS system, respectively, which was 34% and 18.0 mg kWh-1 higher than for the discharge plasma treatment alone. Analysis of the physical and chemical effects indicated that ozone and hydrogen peroxide were important for PNP degradation and UV irradiation and heat from the discharge plasma might be the main physical effects for the activation of PDS.

Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water

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

Mohamed, Alaa; Mechanical Design and Production Engineering Department, Cairo University, 12613 Giza; Production Engineering and Printing Technology Department, Akhbar El Yom Academy, 12655 Giza

2016-02-15

In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO{sub 2} nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity comparedmore » to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles. - Highlights: • Develop effective photocatalyst based on PAN–CNT/TiO{sub 2}–NH{sub 2} composite nanofibers. • High photodegradation efficiency and fast kinetics was obtained. • Regeneration of the composite nanofibers allowed the reuse of these material. • Mechanism of the photocatalytic degradation was proposed. • The flexibility of the composite nanofibers allows use in a continuous operation mode.« less

Antidiabetic activity from cinnamaldydhe encapsulated by nanochitosan

NASA Astrophysics Data System (ADS)

Purbowatingrum; Ngadiwiyana; Fachriyah, E.; Ismiyarto; Ariestiani, B.; Khikmah

2018-04-01

Diabetes mellitus (DM) is a disease characterized by chronic hyperglycemia and metabolic disorders of carbohydrates, proteins, and fats due to reduced function of insulin. Treatment of diabetes can be done by insulin therapy or hypoglycemic drugs. Hypoglycemic drugs usually contain compounds that can inhibit the action of α-glucosidase enzymes that play a role in breaking carbohydrates into blood sugar. Cinnamaldehyde has α-glucosidase inhibit activity because it has a functional group of alkene that is conjugated with a benzene ring and a carbonyl group. However, the use of this compound still provides unsatisfactory results due to its degradation during the absorption process. The solution offered to solve the problem is by encapsulated it within chitosan nanoparticles that serve to protect the bioactive compound from degradation, increases of solubility and delivery of a bioactive compound to the target site by using freeze-drying technique. The value of encapsulation efficiency (EE) of cinnamaldyhde which encapsulated within chitosan nanoparticles is about 74%. Inhibition test result showed that cinnamaldehyde-chitosan nanoparticles at 100 ppm could inhibit α-glucosidase activity in 23.9% with 134,13 in IC50. So it can be concluded that cinnamaldehyde can be encapsulated in nanoparticles of chitosan and proved that it could inhibit α-glucosidase.

Azo dye degradation pathway and bacterial community structure in biofilm electrode reactors.

PubMed

Cao, Xian; Wang, Hui; Zhang, Shuai; Nishimura, Osamu; Li, Xianning

2018-05-31

In this study, the degradation pathway of the azo dye X-3B was explored in biofilm electrode reactors (BERs). The X-3B and chemical oxygen demand (COD) removal efficiencies were evaluated under different voltages, salinities, and temperatures. The removal efficiencies increased with increasing voltage. Additionally, the BER achieved maximum X-3B removal efficiencies of 66.26% and 75.27% at a NaCl concentration of 0.33 g L -1 and temperature of 32 °C, respectively; it achieved a COD removal efficiency of 75.64% at a NaCl concentration of 0.330 g L -1 . Fourier transform infrared spectrometry and gas chromatography-mass spectrometry analysis indicated that the X-3B biodegradation process first involved the interruption of the conjugated double-bond, resulting in aniline, benzodiazepine substance, triazine, and naphthalene ring formation. These compounds were further degraded into lower-molecular-weight products. From this, the degradation pathway of the azo dye X-3B was proposed in BERs. The relative abundances of the microbial community at the phylum and genus levels were affected by temperature, the presence of electrons, and an anaerobic environment in the BERs. To achieve better removal efficiencies, further studies on the functions of the microorganisms are needed. Copyright © 2018. Published by Elsevier Ltd.

CTAB-assisted synthesis of monoclinic BiVO4 photocatalyst and its highly efficient degradation of organic dye under visible-light irradiation.

PubMed

Yin, Wenzong; Wang, Wenzhong; Zhou, Lin; Sun, Songmei; Zhang, Ling

2010-01-15

A highly efficient monoclinic BiVO(4) photocatalyst (C-BVO) was synthesized by an aqueous method with the assistance of cetyltrimethylammonium bromide (CTAB). The structure, morphology and photophysical properties of the C-BVO were characterized by XRD, FE-SEM and diffuse reflectance spectroscopy, respectively. The photocatalytic efficiencies were evaluated by the degradation of rhodamine B (RhB) under visible-light irradiation, revealing that the degradation rate over the C-BVO was much higher than that over the reference BiVO(4) prepared by aqueous method and over the one prepared by solid-state reaction. The efficiency of de-ethylation and that of the cleavage of conjugated chromophore structure were investigated, respectively. The chemical oxygen demand (COD) values of the RhB were measured after the photocatalytic degradation over the C-BVO and demonstrated a 53% decrease in COD. The effects of CTAB on the synthesis of C-BVO were investigated, which revealed that CTAB not only changed the reaction process via the formation of BiOBr as an intermediate, but also facilitated the transition from BiOBr to BiVO(4). Comparison experiments were carried out and showed that the existence of impurity level makes significant contribution to the high photocatalytic efficiency of the C-BVO.

Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water.

PubMed

Mohamed, Alaa; El-Sayed, Ramy; Osman, T A; Toprak, M S; Muhammed, M; Uheida, A

2016-02-01

In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO2 nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity compared to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles. Copyright © 2015 Elsevier Inc. All rights reserved.

Solar/UV-induced photocatalytic degradation of three commercial textile dyes.

PubMed

Neppolian, B; Choi, H C; Sakthivel, S; Arabindoo, Banumathi; Murugesan, V

2002-01-28

The photocatalytic degradation of three commercial textile dyes with different structure has been investigated using TiO(2) (Degussa P25) photocatalyst in aqueous solution under solar irradiation. Experiments were conducted to optimise various parameters viz. amount of catalyst, concentration of dye, pH and solar light intensity. Degradation of all the dyes were examined by using chemical oxygen demand (COD) method. The degradation efficiency of the three dyes is as follows: Reactive Yellow 17(RY17) > Reactive Red 2(RR2) > Reactive Blue 4 (RB4), respectively. The experimental results indicate that TiO(2) (Degussa P25) is the best catalyst in comparison with other commercial photocatalysts such as, TiO(2) (Merck), ZnO, ZrO(2), WO(3) and CdS. Though the UV irradiation can efficiently degrade the dyes, naturally abundant solar irradiation is also very effective in the mineralisation of dyes. The comparison between thin-film coating and aqueous slurry method reveals that slurry method is more efficient than coating but the problems of leaching and the requirement of separation can be avoided by using coating technique. These observations indicate that all the three dyes could be degraded completely at different time intervals. Hence, it may be a viable technique for the safe disposal of textile wastewater into the water streams.

Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

PubMed Central

Al-Sabahi, Jamal; Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

2016-01-01

Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO) nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC) was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region. PMID:28773363

Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol.

PubMed

Al-Sabahi, Jamal; Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

2016-03-28

Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO) nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC) was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

Design and synthesis of metal complexes of (2E)-2-[(2E)-3-phenylprop-2-en-1-ylidene]hydrazinecarbothioamide and their photocatalytic degradation of methylene blue.

PubMed

Krishna, P Murali; Reddy, N B Gopal; Kottam, Nagaraju; Yallur, B C; Katreddi, Hussain Reddy

2013-01-01

The photocatalytic degradation has been considered to be an efficient process for the degradation of organic pollutants, which are present in the effluents released by industries. The photocatalytic bleaching of cationic dye methylene blue was carried out spectrometrically on irradiation of UV light using Cu(II), Ni(II), and Co(II) complexes of (2E)-2-[(2E)-3-phenylprop-2-en-1-ylidene]hydrazinecarbothioamide (HL). The effects of pH and metal ion were studied on the efficiency of the reaction. Cu(II) complex shows better catalytic activity and the highest percentage degradation (~88.8%) of methylene blue was observed at pH 12. A tentative mechanism has also been proposed for the photocatalytic degradation of methylene blue.

[Immobilization of introduced bacteria and degradation of pyrene and benzo(alpha) pyrene in soil by immobilized bacteria].

PubMed

Wang, Xin; Li, Peijun; Song, Shouzhi; Zhong, Yong; Zhang, Hui; Verkhozina, E V

2006-11-01

In this study, introduced bacteria were applied in the bioremediation of pyrene and benzo (alpha) pyrene in organic pollutants-contaminated soils, aimed to test whether it was feasible to introduce bacteria to environmental engineering. Three introduced bacteria were immobilized separately or together to degrade the pyrene and benzo (alpha) pyrene in soil, taking dissociated bacteria as the control, and comparing with three indigenous bacteria. The results showed that immobilized introduced bacteria, either single or mixed, had higher degradation efficiency than dissociated bacteria. Compared with indigenous bacteria, some introduced bacteria had predominance to some degree. The introduced bacteria-mixture had better degradation efficiency after being immobilized. The degradation rate of pyrene and benzo(alpha) pyrene after treated with immobilized bacteria-( B61-B67)-mixture for 96 hours was 43.49% and 38.55%, respectively.

Detecting and monitoring deforestation and forest degradation: Issues and obstacles for Southeast Asia

Treesearch

Douglas Muchoney; Sharon Hamann

2013-01-01

Forest degradation can be defined as the loss of forest volume, biomass and/or forest productivity caused by natural or human influences. Achieving Reduced Emissions from Deforestation and Forest Degradation (REDD+) requires that deforestation and degradation can be efficiently, reliably, and cost-effectively detected and quantified, often where ground and aerial...

Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling

NASA Astrophysics Data System (ADS)

Ju, Yaping; Zhang, Chuhua

2016-03-01

Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

Biodecolorization of recalcitrant dye as the sole sourceof nutrition using Curvularia clavata NZ2 and decolorization ability of its crude enzymes.

PubMed

Neoh, Chin Hong; Lam, Chi Yong; Lim, Chi Kim; Yahya, Adibah; Bay, Hui Han; Ibrahim, Zaharah; Noor, Zainura Zainon

2015-08-01

Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet-visible (UV-vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5's metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90%. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88-92%) and 1000 ppm (70-77%) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5.

Electrochemically modified dissolved organic matter accelerates the combining photodegradation and biodegradation of 17α-ethinylestradiol in natural aquatic environment.

PubMed

He, Huan; Huang, Bin; Fu, Gen; Xiong, Dan; Xu, Zhixiang; Wu, Xinhao; Pan, Xuejun

2018-06-15

The photochemical conversion and microbial transformation of pollutants mediated by dissolved organic matter (DOM), including 17α-ethinylestradiol (EE2), are often accompanied in natural water. However, there are few studies to explore the connection and mechanism between the two processes. This research aims to investigate the mechanism of DOM after electrochemically modification mediated EE2 combining photodegradation and biodegradation in the environment and it want to explain the natural phenomena of DOM after electrochemical advanced treatment entering the water environment mediated EE2 natural degradation. The results showed that combining photodegradation with biodegradation rates of EE2 mediated by DOM and electrochemically modified DOM (E-DOM) were promoted obviously. The efficiency of EE2 biodegradation was shown to be strongly correlated with electron accepting capacity (EAC) of DOM. Electrochemical modification can increase the EAC of DOM leading to EE2 biodegradation accelerated, and it also can form more triplet-state DOM moieties to promote the EE2 photodegradation in irradiation conditions, due to the increasing of quinone-type structures in DOM. Moreover, cell polymeric secretion (CPS) secreted from the microorganism could be stimulated to an excited state by irradiation, and that also accelerated EE2 degradation. Photolysis combined with biochemical degradation yielded less toxic degradation products. This study shows that the emission of DOM in wastewater after electrochemical treatment could accelerate estrogen degradation and play a positive role on the pollutant transformation in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

The effect of operational parameters on the photocatalytic degradation of Congo red organic dye using ZnO-CdS core-shell nano-structure coated on glass by Doctor Blade method.

PubMed

Habibi, Mohammad Hossein; Rahmati, Mohammad Hossein

2015-02-25

Photocatalytic degradation of Congo red was investigated using ZnO-CdS core-shell nano-structure coated on glass by Doctor Blade method in aqueous solution under irradiation. Field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques were used for the morphological and structural characterization of ZnO-CdS core-shell nanostructures. XRD results showed diffractions of wurtzite zinc oxide core and wurtzite cadmium sulfide shell. FESEM results showed that nanoparticles are nearly hexagonal with an average diameter of about 50 nm. The effect of catalyst loading, UV-light irradiation time and solution pH on photocatalytic degradation of Congo red was studied and optimized values were obtained. Results showed that the employment of efficient photocatalyst and selection of optimal operational parameters may lead to complete decolorization of dye solutions. It was found that ZnO-CdS core-shell nano-structure is more favorable for the degradation of Congo red compare to pure ZnO or pure CdS due to lower electron hole recombination. The results showed that the photocatalytic degradation rate of Congo red is enhanced with increasing the content of ZnO up to ZnO(0.2 M)/CdS(0.075 M) which is reached 88.0% within 100 min irradiation. Copyright © 2014 Elsevier B.V. All rights reserved.

Augmenting atrazine and hexachlorobenzene degradation under different soil redox conditions in a bioelectrochemistry system and an analysis of the relevant microorganisms.

PubMed

Wang, Hui; Cao, Xian; Li, Lei; Fang, Zhou; Li, Xianning

2018-01-01

Soil microbial fuel cells (MFCs) are a sustainable technology that degrades organic pollutants while generating electricity. However, there have been no detailed studies of the mechanisms of pollutant degradation in soil MFCs. In this study, the effects of external resistance and electrode effectiveness on atrazine and hexachlorobenzene (HCB) degradation were evaluated, the performance of soil MFCs in the degradation of these pollutants under different soil redox conditions was assessed, and the associated microorganisms in the anode were investigated. With an external resistance of 20Ω, the degradation efficiencies of atrazine and HCB were 95% and 78%, respectively. The degradation efficiency, degradation rate increased with decreasing external resistance, while the half-life decreased. There were different degradation trends for different pollutants under different soil redox conditions. The fastest degradation rate of atrazine was in the upper MFC section (aerobic), whereas that of HCB was in the lower MFC section (anaerobic). The results showed that electrode effectiveness played a significant role in pollution degradation. In addition, the microbial community analysis demonstrated that Proteobacteria, especially Deltaproteobacteria involved in current generation was extremely abundant (27.49%) on soil MFC anodes, although the percentage abundances of atrazine degrading Rhodocyclaceae (8.77%), Desulfitobacterium (0.64%), and HCB degrading Desulfuromonas (0.73%), were considerably lower. The results of the study suggested that soil MFCs can enhance the degradation of atrazine and HCB, and bioelectrochemical reduction was the main mechanism for the pollutants degradation. Copyright © 2017 Elsevier Inc. All rights reserved.

Kinetic study of acetaminophen degradation by visible light photocatalysis.

PubMed

Gotostos, Mary Jane N; Su, Chia-Chi; De Luna, Mark Daniel G; Lu, Ming-Chun

2014-01-01

In this work, a novel photocatalyst K3[Fe(CN)6]/TiO2 synthesized via a simple sol-gel method was utilized to degrade acetaminophen (ACT) under visible light with the use of blue and green LED lights. Parameters (medium pH, initial concentration of reactant, catalyst concentration, temperature, and number of blue LED lights) affecting photocatalytic degradation of ACT were also investigated. The experimental result showed that compared to commercially available Degussa P-25 (DP-25) photocatalyst, K3[Fe(CN)6]/TiO2 gave higher degradation efficiency and rate constant (kapp) of ACT. The degradation efficiency or kapp decreased with increasing initial ACT concentration and temperature, but increased with increased number of blue LED lamps. Additionally, kapp increased as initial pH was increased from 5.6 to 6.9, but decreased at a high alkaline condition (pH 8.3). Furthermore, the degradation efficiency and kapp of ACT increased as K3[Fe(CN)6]/TiO2 loading was increased to 1 g L(-1) but decreased and eventually leveled off at photocatalyst loading above this value. Photocatalytic degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system follows a pseudo-first-order kinetics. The Langmuir-Hinshelwood equation was also satisfactorily used to model the degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system indicated by a satisfactory linear correlation between 1/kapp and Co, with kini = 6.54 × 10(-4) mM/min and KACT = 17.27 mM(-1).

Degradation of pesticide mixture on modified matrix of a biopurification system with alternatives lignocellulosic wastes.

PubMed

Urrutia, C; Rubilar, O; Tortella, G R; Diez, M C

2013-08-01

The biobed systems were designed to retain and to degrade pesticides through the properties of a biomixture composed of straw (ST), topsoil and peat (PT) 2:1:1 v/v. The ST is the main substrate in the biomixture, as it allows the proliferation of fungi that promotes pesticide degradation. The use of readily available components in the biomixture is an important aspect to build a biobed. Therefore, potential use of readily available wastes as barley husk (BH), sawdust (SW) and oat husk (OH), as total or partial substitutes of ST were tested in pesticide degradation studies. Metabolite formation and the biological activities were also evaluated. Biomixture composed of OH was highly efficient in pesticide degradation, with t½ values of 28.6, 58.9 and 26.8 d for atrazine (ATZ), chlorpyrifos (CHL) and isoproturon (ISP). On the other hand, comparable for degrading capacities with the ST based biomixture were obtained with SW and BH, but only as partial replacement. Contrarily, high t½ values (more than 100 d) were obtained in biomixtures with total substitution of ST by SW or BH. Metabolite formation was observed in all biomixtures tested, but without clear formation patterns. Moreover, high and stable biological activity was observed in the biomixtures composed of OH. Therefore, our results demonstrated that ST can be partial or totally replaced by OH in the biomixture allowing an efficient degradation of pesticide mixture. However, it is recommended that ST can be only partially replaced by BH and SW in the biomixture to allow efficient pesticide degradation. Copyright © 2013. Published by Elsevier Ltd.

Current State of Knowledge in Microbial Degradation of Polycyclic Aromatic Hydrocarbons (PAHs): A Review

PubMed Central

Ghosal, Debajyoti; Ghosh, Shreya; Dutta, Tapan K.; Ahn, Youngho

2016-01-01

Polycyclic aromatic hydrocarbons (PAHs) include a group of organic priority pollutants of critical environmental and public health concern due to their toxic, genotoxic, mutagenic and/or carcinogenic properties and their ubiquitous occurrence as well as recalcitrance. The increased awareness of their various adverse effects on ecosystem and human health has led to a dramatic increase in research aimed toward removing PAHs from the environment. PAHs may undergo adsorption, volatilization, photolysis, and chemical oxidation, although transformation by microorganisms is the major neutralization process of PAH-contaminated sites in an ecologically accepted manner. Microbial degradation of PAHs depends on various environmental conditions, such as nutrients, number and kind of the microorganisms, nature as well as chemical property of the PAH being degraded. A wide variety of bacterial, fungal and algal species have the potential to degrade/transform PAHs, among which bacteria and fungi mediated degradation has been studied most extensively. In last few decades microbial community analysis, biochemical pathway for PAHs degradation, gene organization, enzyme system, genetic regulation for PAH degradation have been explored in great detail. Although, xenobiotic-degrading microorganisms have incredible potential to restore contaminated environments inexpensively yet effectively, but new advancements are required to make such microbes effective and more powerful in removing those compounds, which were once thought to be recalcitrant. Recent analytical chemistry and genetic engineering tools might help to improve the efficiency of degradation of PAHs by microorganisms, and minimize uncertainties of successful bioremediation. However, appropriate implementation of the potential of naturally occurring microorganisms for field bioremediation could be considerably enhanced by optimizing certain factors such as bioavailability, adsorption and mass transfer of PAHs. The main purpose of this review is to provide an overview of current knowledge of bacteria, halophilic archaea, fungi and algae mediated degradation/transformation of PAHs. In addition, factors affecting PAHs degradation in the environment, recent advancement in genetic, genomic, proteomic and metabolomic techniques are also highlighted with an aim to facilitate the development of a new insight into the bioremediation of PAH in the environment. PMID:27630626

Efficient degradation of trichloroethylene in water using persulfate activated by reduced graphene oxide-iron nanocomposite.

PubMed

Ahmad, Ayyaz; Gu, Xiaogang; Li, Li; Lv, Shuguang; Xu, Yisheng; Guo, Xuhong

2015-11-01

Graphene oxide (GO) and nano-sized zero-valent iron-reduced graphene oxide (nZVI-rGO) composite were prepared. The GO and nZVI-rGO composite were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The size of nZVI was about 6 nm as observed by TEM. The system of nZVI-rGO and persulfate (PS) was used for the degradation of trichloroethylene (TCE) in water, and showed 26.5% more efficiency as compared to nZVI/PS system. The different parameters were studied to determine the efficiency of nZVI-rGO to activate the PS system for the TCE degradation. By increasing the PS amount, TCE removal was also improved while no obvious effect was observed by varying the catalyst loading. Degradation was decreased as the TCE initial concentration was increased from 20 to 100 mg/L. Moreover, when initial solution pH was increased, efficiency deteriorated to 80%. Bicarbonate showed more negative effect on TCE removal among the solution matrix. To better understand the effects of radical species in the system, the scavenger tests were performed. The •SO4(-) and •O2(-) were predominant species responsible for TCE removal. The nZVI-rGO-activated PS process shows potential applications in remediation of highly toxic organic contaminants such as TCE present in the groundwater. Graphical abstract Persulfate activated by reduced graphene oxide and nano-sized zero-valent iron composite can be used for efficient degradation of trichloroethylene (TCE) in water.

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.

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

PubMed

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

2013-01-01

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

Sustainable biodegradation of phenol by immobilized Bacillus sp. SAS19 with porous carbonaceous gels as carriers.

PubMed

Ke, Qian; Zhang, Yunge; Wu, Xilin; Su, Xiaomei; Wang, Yuyang; Lin, Hongjun; Mei, Rongwu; Zhang, Yu; Hashmi, Muhammad Zaffar; Chen, Chongjun; Chen, Jianrong

2018-09-15

In this study, high-efficient phenol-degrading bacterium Bacillus sp. SAS19 which was isolated from activated sludge by resuscitation-promoting factor (Rpf) addition, were immobilized on porous carbonaceous gels (CGs) for phenol degradation. The phenol-degrading capabilities of free and immobilized Bacillus sp. SAS19 were evaluated under various initial phenol concentrations. The obtained results showed that phenol could be removed effectively by both free and immobilized Bacillus sp. SAS19. Furthermore, for degradation of phenol at high concentrations, long-term utilization and recycling were more readily achieved for immobilized bacteria as compared to free bacteria. Immobilized bacteria exhibited significant increase in phenol-degrading capabilities in the third cycle of recycling and reuse, which demonstrated 87.2% and 100% of phenol (1600 mg/L) degradation efficiency at 12 and 24 h, respectively. The present study revealed that immobilized Bacillus sp. SAS19 can be potentially used for enhanced treatment of synthetic phenol-laden wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Insights into the mechanism of persulfate activated by rice straw biochar for the degradation of aniline.

PubMed

Wu, Yao; Guo, Jing; Han, Yijie; Zhu, Junyi; Zhou, Lixiang; Lan, Yeqing

2018-06-01

This study investigated the degradation of aniline by persulfate (PS) activated with rice straw biochar (RSBC). The results demonstrate that aniline could be rapidly decomposed by a combination of PS and RSBC. The degradation efficiency of aniline was up to 94.1% within 80 min, and meanwhile 52% of the total organic carbon was removed. In the initial pH range of 3-9, aniline could be efficiently removed. Reactive species resulting in the rapid degradation of aniline were investigated via radical and hole quenching experiments with various scavengers (e.g., methanol, tert-butyl alcohol and EDTA) and electron paramagnetic resonance technique. Based on the analysis and observation made here, it is speculated that the predominant reactive species responsible for the degradation of aniline may be holes instead of SO 4 - and OH radicals. It is concluded that RSBC could be used as an effective catalyst to activate PS for the degradation of aniline. Copyright © 2018 Elsevier Ltd. All rights reserved.

Bio-softening of mature coconut husk for facile coir recovery.

PubMed

Suganya, D S; Pradeep, S; Jayapriya, J; Subramanian, S

2007-06-01

Bio-softening of the mature coconut husk using Basidiomyceteous fungi was attempted to recover the soft and whiter fibers. The process was faster and more efficient in degrading lignin and toxic phenolics. Phanerochaete chrysosporium, Pleurotus eryngii and Ceriporiopsis subvermispora were found to degrade lignin efficiently without any appreciable loss of cellulose, yielding good quality fiber ideal for dyeing.

Biodegradation of 3,5-dimethyl-2,4-dichlorophenol in saline wastewater by newly isolated Penicillium sp. yz11-22N2.

PubMed

Yan, Zhou; He, Huijun; Yang, Chunping; Zeng, Guangming; Luo, Le; Jiao, Panpan; Li, Huiru; Lu, Li

2017-07-01

In this study, the performance of 3,5-dimethyl-2,4-dichlorophenol (DCMX) degradation by a screened strain was investigated. 18S rDNA and the neighbor-joining method were used for identification of the isolated strain. The results of phylogenetic analysis and scanning electron micrographs showed that the most probable identity of the screened strain should be Penicillium sp. Growth characteristics of Penicillium sp. and degradation processes of DCMX were examined. Fourier transform infrared spectroscopy of the inoculated DCMX solution was recorded, which supported the capacity of DCMX degradation by the screened Penicillium sp. Under different salinity conditions, the highest growth rate and removal efficiency for DCMX were obtained at pH6.0. The removal efficiency decreased from 100% to 66% when the DCMX concentration increased from 5 to 60mg/L, respectively. Using a Box-Behnken design, the maximum DCMX removal efficiency was determined to be 98.4%. With acclimation to salinity, higher removal efficiency could be achieved. The results demonstrate that the screened Penicillium sp. has the capability for degradation of DCMX. Copyright © 2017. Published by Elsevier B.V.

Temporal Alterations in the Secretome of the Selective Ligninolytic Fungus Ceriporipsis subvermispora during growth on Aspen Wood Reveal this Organism's Strategy for Degrading Lighnocellulose

Treesearch

Chiaki Hori; Jill Gaskell; Kiyohiko Igarashi; Phil Kersten; Michael Mozuch; Masahiro Samejima; Dan Cullen

2014-01-01

The white-rot basidiomycetes efficiently degrade all wood cell wall polymers. Generally, these fungi simultaneously degrade cellulose and lignin, but certain organisms, such as Ceriporiopsis subvermispora, selectively remove lignin in advance of cellulose degradation. However, relatively little is known about themechanismof selective ligninolysis. To...

Degradation of polycyclic aromatic hydrocarbons in crumb tyre rubber catalysed by rutile TiO2 under UV irradiation.

PubMed

Yu, Kai; Huang, Linyue; Lou, Lan-Lan; Chang, Yue; Dong, Yanling; Wang, Huan; Liu, Shuangxi

2015-01-01

The polycyclic aromatic hydrocarbons (PAHs) in crumb tyre rubber were firstly degraded under UV irradiation in the presence of rutile TiO2 and hydrogen peroxide. The effects of light intensity, catalyst amount, oxidant amount, initial pH value, co-solvent content, and reaction time on degradation efficiency of typical PAHs in crumb tyre rubber were studied. The results indicated that UV irradiation, rutile TiO2, and hydrogen peroxide were beneficial to the degradation of PAHs and co-solvent could accelerate the desorption of PAHs from crumb tyre rubber. Up to 90% degradation efficiency of total 16 PAHs could be obtained in the presence of rutile TiO2 (1 wt%) and hydrogen peroxide (1.0 mL) under 1800 µW cm(-2) UV irradiation for 48 h. The high molecular weight PAHs (such as benz(a)pyrene) were more difficult to be degraded than low molecular weight PAHs (such as phenanthrene, chrysene). Moreover, through the characterization of reaction solution and degradation products via GC-MS, it was proved that the PAHs in crumb tyre rubber were successfully degraded.

Improved WO3 photocatalytic efficiency using ZrO2 and Ru for the degradation of carbofuran and ampicillin.

PubMed

Gar Alalm, Mohamed; Ookawara, Shinichi; Fukushi, Daisuke; Sato, Akira; Tawfik, Ahmed

2016-01-25

The photocatalytic degradation of carbofuran (pesticide) and ampicillin (pharmaceutical) using synthesized WO3/ZrO2 nanoparticles under simulated solar light was investigated. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectra analyses were used to characterize the prepared catalysts. The optimum ratio of WO3 to ZrO2 was determined to be 1:1 for the degradation of both contaminants. The degradation of carbofuran and ampicillin by WO3/ZrO2 after 240 min of irradiation was 100% and 96%, respectively. Ruthenium (Ru) was employed as an additive to WO3/ZrO2 to enhance the photocatalytic degradation rate. Ru/WO3/ZrO2 exhibited faster degradation rates than WO3/ZrO2. Furthermore, 100% and 97% degradation of carbofuran and ampicillin, respectively, was achieved using Ru/WO3/ZrO2 after 180 min of irradiation. The durability of the catalyst was investigated by reusing the same suspended catalyst, which achieved 92% of its initial efficiency. The photocatalytic degradation of ampicillin and carbofuran followed pseudo-first order kinetics according to the Langmuir-Hinshelwood model. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of ZnO Photocatalyst for the Efficient and Rapid Photocatalytic Degradation of Azo Dyes.

PubMed

Chen, Xiaoqing; Wu, Zhansheng; Liu, Dandan; Gao, Zhenzhen

2017-12-01

Zinc oxide (ZnO) photocatalysts were synthesized by sol-gel method using zinc acetate as precursor for degradation of azo dyes under UV irradiation. The resultant samples were characterized by different techniques, such as XRD, SEM, and EDX. The influence of preparation conditions such as calcination temperature and composite ratio on the degradation of methyl orange (MO) was investigated. ZnO prepared with a composite ratio of 4:1 and calcination temperature of 400 °C exhibited 99.70% removal rate for MO. The effect of operation parameters on the degradation was also studied. Results showed that the removal rate of azo dyes increased with the increased dosage of catalyst and decreased initial concentration of azo dyes and the acidic condition is favorable for degradation. Furthermore, the kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of azo dyes fitted the first-order kinetics and superoxide ions were the main species. The proposed photocatalyst can efficiently and rapidly degrade azo dyes; thus, this economical and environment-friendly photocatalyst can be applied to the treatment of wastewater contaminated with synthetic dyes.

Using soil enzymes to explain observed differences in the response of soil decomposition to nitrogen fertilization

NASA Astrophysics Data System (ADS)

Stone, M.; Weiss, M.; Goodale, C. L.

2010-12-01

Soil microbes produce extracellular enzymes that degrade a variety of carbon-rich polymers contained within soil organic matter (SOM). These enzymes are key regulators of the terrestrial carbon cycle. However, basic information about the kinetics of extracellular enzymes and key environmental variables that regulate their catalytic ability is lacking. This study aims to clarify the mechanisms by which microbial carbon-degrading enzymes drive different responses to nitrogen (N) fertilization in soil decomposition at two sites with long-term N fertilization experiments, the Bear Brook (BB) forest in Maine and Fernow Forest (FF) in West Virginia. We examined a suite of cellulolytic and lignolytic enzymes that break down common SOM constituents. We hypothesized that enzymes derived from the site with a higher mean annual temperature (FF) would be more heat-tolerant, and retain their catalytic efficiency (Km) as temperature rises, relative to enzymes from the colder environment (BB). We further hypothesized that cellulolytic enzyme activity would be unaffected by N, while oxidative enzyme activity would be suppressed in N-fertilized soils. To test these hypotheses and examine the interactive effects of temperature and N, we measured enzyme activity in unfertilized and N-fertilized soils under a range of laboratory temperature manipulations. Preliminary results show a significant decrease in cellulolytic enzyme efficiency with temperature at the colder site (BB), as well as a significant increase in efficiency due to N-fertilization for two cellulolytic enzymes. Oxidative enzyme activity shows a marginally significant reduction due to N-fertilization at BB. These results suggest that soil warming may produce a negative feedback on carbon turnover in certain climates, while N-fertilization may alter the relative decomposition rates of different soil organic matter constituents. FF activity will be analyzed in a similar manner and the two sites will be compared in order to fully assess our hypotheses.

Rapid degradation of aniline in aqueous solution by ozone in the presence of zero-valent zinc.

PubMed

Zhang, Jing; Wu, Yao; Qin, Chao; Liu, Liping; Lan, Yeqing

2015-12-01

The effects of Zn(0) dosage from 0.1 to 1.3gL(-1), pH from 2 to 12 and temperature from 288 to 318K on the degradation of aniline in aqueous solution by ozone in the presence of Zn(0) were investigated through batch experiments. The results demonstrated that Zn(0) had a significantly synergistic role in the degradation of aniline by ozone. A complete decomposition of the initial aniline (10mgL(-1)) was achieved by ozone together with Zn(0) within 25min, and meanwhile nearly 70% of the total organic carbon in the solution was removed. The decomposition efficiency of aniline markedly increased with an increase of Zn(0) dosage. However, temperature exerted a slight impact on the degradation of aniline and the optimum removal efficiency of aniline was realized at 298K. Aniline was efficiently degraded at all the tested pHs except for 12. Free radicals were investigated by electron paramagnetic resonance technique and free radical scavengers. H2O2 concentration generated during the reactions was analyzed using a photometric method. Based on the results obtained in this study, it is proposed that O2(-) instead of OH is the dominant active species responsible for the degradation of aniline. It is concluded that ozone combined with Zn(0) is an effective and promising approach to the degradation of organic pollutants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Probiotics and Other Key Determinants of Dietary Oxalate Absorption1

PubMed Central

Liebman, Michael; Al-Wahsh, Ismail A.

2011-01-01

Oxalate is a common component of many foods of plant origin, including nuts, fruits, vegetables, grains, and legumes, and is typically present as a salt of oxalic acid. Because virtually all absorbed oxalic acid is excreted in the urine and hyperoxaluria is known to be a considerable risk factor for urolithiasis, it is important to understand the factors that have the potential to alter the efficiency of oxalate absorption. Oxalate bioavailability, a term that has been used to refer to that portion of food-derived oxalate that is absorbed from the gastrointestinal tract (GIT), is estimated to range from 2 to 15% for different foods. Oxalate bioavailability appears to be decreased by concomitant food ingestion due to interactions between oxalate and coingested food components that likely result in less oxalic acid remaining in a soluble form. There is a lack of consensus in the literature as to whether efficiency of oxalate absorption is dependent on the proportion of total dietary oxalate that is in a soluble form. However, studies that directly compared foods of varying soluble oxalate contents have generally supported the proposition that the amount of soluble oxalate in food is an important determinant of oxalate bioavailability. Oxalate degradation by oxalate-degrading bacteria within the GIT is another key factor that could affect oxalate absorption and degree of oxaluria. Studies that have assessed the efficacy of oral ingestion of probiotics that provide bacteria with oxalate-degrading capacity have led to promising but generally mixed results, and this remains a fertile area for future studies. PMID:22332057

Solar-based detoxification of phenol and p-nitrophenol by sequential TiO2 photocatalysis and photosynthetically aerated biological treatment.

PubMed

Essam, Tamer; Aly Amin, Magdy; El Tayeb, Ossama; Mattiasson, Bo; Guieysse, Benoit

2007-04-01

Simulated solar UV/TiO(2) photocatalysis was efficient to detoxify a mixture of 100 mgphenoll(-1) and 50 mgp-nitrophenol (PNP) l(-1) and allow the subsequent biodegradation of the remaining pollutants and their photocatalytic products under photosynthetic aeration with Chlorella vulgaris. Photocatalytic degradation of phenol and PNP was well described by pseudo-first order kinetics (r(2)>0.98) with removal rate constants of 1.9x10(-4) and 2.8x10(-4)min(-1), respectively, when the pollutants were provided together and 5.7x10(-4) and 9.7x10(-4)min(-1), respectively, when they were provided individually. Photocatalytic pre-treatment of the mixture during 60 h removed 50+/-1% and 62+/-2% of the phenol and PNP initially present but only 11+/-3% of the initial COD. Hydroquinone, nitrate and catechol were identified as PNP photocatalytic products and catechol and hydroquinone as phenol photocatalytic products. Subsequent biological treatment of the pre-treated samples removed the remaining contaminants and their photocatalytic products as well as 81-83% of the initial COD, allowing complete detoxification of the mixture to C. vulgaris. Similar detoxification efficiencies were recorded after biological treatment of the irradiated mixture with activated sludge microflora or with an acclimated consortia composed of a phenol-degrading Alcaligenes sp. and a PNP-degrading Arthrobacter sp., although the acclimated strains biodegraded the remaining pollutants faster. Biological treatment of the non-irradiated mixture was inefficient due to C. vulgaris inhibition.

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX

PubMed Central

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-01-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 – HdmX and Wip1, leading to efficient elimination of tumour cells. PMID:21546907

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX.

PubMed

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-11-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 - HdmX and Wip1, leading to efficient elimination of tumour cells.

Solar and Galactic Cosmic Rays Observed by SOHO

NASA Astrophysics Data System (ADS)

Curdt, W.; Fleck, B.

Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to ≈77% of its original level over roughly 1 1/2 solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mechanism. We compare the daily CRF observed by the Oulu station with the daily SOHO SEU rate and with the degradation curve of the solar arrays. The Oulu CRF and the SOHO SSR SEU rate are both modulated by the solar cycle and are highly correlated, except for sharp spikes in the SEU rate, caused by isolated SEP events, which also show up as discontinuities in the otherwise slowly decreasing solar ray efficiency. This allows to discriminate between effects with solar and non-solar origin and to compare the relative strength of both. We find that during solar cycle 23 (1996 Apr 1 -- 2008 Aug 31) only 6% of the total number of SSR SEUs were caused by SEPs; the remaining 94% were due to galactic cosmic rays. During the maximum period of cycle 23 (2000 Jan 1 -- 2003 Dec 31), the SEP contribution increased to 22%, and during 2001, the year with the highest SEP rate, to 30%. About 40% of the total solar array degradation during the 17 years from Jan 1996 through Feb 2013 can be attributed to proton events, i.e. the effect of a series of short-lived, violent SEP events is comparable to the cycle-integrated damage by cosmic rays.

Efficient biodegradation of cyanide and ferrocyanide by Na-alginate beads immobilized with fungal cells of Trichoderma koningii.

PubMed

Zhou, Xiaoying; Liu, Lixing; Chen, Yunpeng; Xu, Shufa; Chen, Jie

2007-09-01

Cyanide or metal cyanide contaminations have become serious environmental and food-health problems. A fungal mutant of Trichoderma koningii, TkA8, constructed by restriction enzyme-mediated integration, has been verified to have a high cyanide degradation ability in our previous study. In this study, the mutant cells were entrapped in sodium-alginate (Na-alginate) immobilization beads to degrade cyanide and ferrocyanide in a liquid mineral medium. The results showed that the fungus in immobilization beads consisting of 3% Na-alginate and 3% CaCl2 could degrade cyanide more efficiently than a nonimmobilized fungal culture. For maximum degradation efficiency, the optimal ratio of Na-alginate and wet fungal biomass was 20:1 (m/m) and the initial pH was 6.5. In comparison, cell immobilization took at least 3 and 8 days earlier, respectively, to completely degrade cyanide and ferrocyanide. In addition, we showed that the immobilized beads could be easily recovered from the medium and reused for up to 5 batches without significant losses of fungal remediation abilities. The results of this study provide a promising alternative method for the large-scale remediation of soil or water systems from cyanide contamination.

Dissolving microneedles for DNA vaccination: Improving functionality via polymer characterization and RALA complexation

PubMed Central

Cole, Grace; McCaffrey, Joanne; Ali, Ahlam A.; McBride, John W.; McCrudden, Cian M.; Vincente-Perez, Eva M.; Donnelly, Ryan F.; McCarthy, Helen O.

2017-01-01

ABSTRACT DNA vaccination holds the potential to treat or prevent nearly any immunogenic disease, including cancer. To date, these vaccines have demonstrated limited immunogenicity in vivo due to the absence of a suitable delivery system which can protect DNA from degradation and improve transfection efficiencies in vivo. Recently, microneedles have been described as a novel physical delivery technology to enhance DNA vaccine immunogenicity. Of these devices, dissolvable microneedles promise a safe, pain-free delivery system which may simultaneously improve DNA stability within a solid matrix and increase DNA delivery compared to solid arrays. However, to date little work has directly compared the suitability of different dissolvable matrices for formulation of DNA-loaded microneedles. Therefore, the current study examined the ability of 4 polymers to formulate mechanically robust, functional DNA loaded dissolvable microneedles. Additionally, complexation of DNA to a cationic delivery peptide, RALA, prior to incorporation into the dissolvable matrix was explored as a means to improve transfection efficacies following release from the polymer matrix. Our data demonstrates that DNA is degraded following incorporation into PVP, but not PVA matrices. The complexation of DNA to RALA prior to incorporation into polymers resulted in higher recovery from dissolvable matrices, and increased transfection efficiencies in vitro. Additionally, RALA/DNA nanoparticles released from dissolvable PVA matrices demonstrated up to 10-fold higher transfection efficiencies than the corresponding complexes released from PVP matrices, indicating that PVA is a superior polymer for this microneedle application. PMID:27846370

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.

CAT-tailing as a fail-safe mechanism for efficient degradation of stalled nascent polypeptides

PubMed Central

Kostova, Kamena K.; Hickey, Kelsey L.; Osuna, Beatriz A.; Hussmann, Jeffrey A.; Frost, Adam; Weinberg, David E.; Weissman, Jonathan S.

2017-01-01

Ribosome stalling leads to recruitment of the Ribosome Quality control Complex (RQC), which targets the partially synthesized polypeptide for proteasomal degradation through the action of the ubiquitin ligase Ltn1p. A second core RQC component, Rqc2p, modifies the nascent polypeptide by adding a Carboxy-terminal Alanine and Threonine (CAT) tail through a non-canonical elongation reaction. Here we explore the role of CATtailing in nascent-chain degradation in budding yeast. We show that Ltn1p can efficiently access only nascent chain lysines immediately proximal to the ribosome exit tunnel. For substrates without Ltn1p-accessible lysines, CAT-tailing enables degradation by exposing lysines sequestered in the ribosome exit tunnel. Thus, CAT-tails do not serve as a degron, but rather provide a fail-safe mechanism that expands the range of RQC-degradable substrates. PMID:28751611

Photochemical and photocatalytic degradation of trans-resveratrol.

PubMed

Silva, Cláudia Gomes; Monteiro, Judith; Marques, Rita R N; Silva, Adrián M T; Martínez, Cristina; Canle, Moisés; Faria, Joaquim Luís

2013-04-01

Photochemical and photocatalytic degradation of the emerging pollutant trans-resveratrol has been studied under different irradiation wavelengths and using different TiO2 catalysts. trans-Resveratrol was more easily degraded when irradiated using the whole spectral range (UV-Vis) rather than with UV and near-UV to visible irradiation. The main intermediate of trans-resveratrol phototransformation was identified as its isomer cis-resveratrol. Different TiO2 catalysts were used to carry out the photocatalytic degradation of trans-resveratrol. Catalysts properties such as crystallite dimensions, surface area and presence of hydroxy surface groups are shown to be crucial to the photocatalytic efficiency of the materials tested. From the point of view of trans-resveratrol abatement, the photocatalytic process was more efficient than the pure photochemical one resulting in higher degradation rates and higher organic content removal. Six photoproducts of trans-resveratrol phototransformation were identified mainly resulting from the attack of the hydroxyl radical to the organic molecule.

Biodegradation of phthalate esters by newly isolated Rhizobium sp. LMB-1 and its biochemical pathway of di-n-butyl phthalate.

PubMed

Tang, W-J; Zhang, L-S; Fang, Y; Zhou, Y; Ye, B-C

2016-07-01

To isolate a novel strain that could degrade many kinds PAEs efficiently and investigate the DBP-degrading pathway in this strain. Based on its 16S rRNA gene sequence, the strain was identified as Rhizobium sp. This strain, named LMB-1, can also utilize phthalates, such as DEHP, DMP, DBP and DEP. During the degradation of DBP, six possible metabolites, diethyl phthalate, mono-ethyl phthalate, di-methyl phthalate, mono-methyl phthalate, phthalic acid and tartaric acid, were identified by gas chromatography-mass spectrometry (GC-MS) analysis, and the degradation pathway of DBP was also identified in this study. In summary, strain LMB-1, identified as Rhizobium sp., was found to be capable of efficiently degrading PAEs, and it was determined that the strain degraded DMP completely within 45 h. DEP, DMP, MEP, MMP, PA and tartaric acid were detected during the course of DBP degradation by LMB-1. We propose that this strain could completely degrade DBP or other PAEs. Our results offer a novel and potential candidate, Rhizobium sp. LMB-1, for use in the bioremediation of cultivated soil contaminated by PAEs. This is the first report concerning the complete degradation of phthalate esters by Rhizobium sp. © 2016 The Society for Applied Microbiology.

Synthesis of Ce doped ZnO nanoparticles coupled with graphene oxide as efficient photocatalyst for the degradation of dye under day light

NASA Astrophysics Data System (ADS)

Labhane, P. K.; Patle, L. B.; Huse, V. R.; Sonawane, G. H.

2018-05-01

Ce doped ZnO nanoparticles coupled with graphene oxide (Ce-ZnO/GO) photocatalyst was prepared by co-precipitation and wet impregnation method. The effect of Ce doping on ZnO and ZnO-GO composite has been evaluated by using XRD, Williamson-Hall Plot, FESEM and EDX data. Solar light photocatalytic activities of samples were evaluated spectrophotometrically by the degradation of methylene blue (MB). Ce doped ZnO coupled with GO shows excellent catalytic efficiency compared to other samples, degrading MB completely within 120 min under day light.

Conversion of xylan by recyclable spores of Bacillus subtilis displaying thermophilic enzymes.

PubMed

Mattossovich, Rosanna; Iacono, Roberta; Cangiano, Giuseppina; Cobucci-Ponzano, Beatrice; Isticato, Rachele; Moracci, Marco; Ricca, Ezio

2017-11-28

The Bacillus subtilis spore has long been used to display antigens and enzymes. Spore display can be accomplished by a recombinant and a non-recombinant approach, with the latter proved more efficient than the recombinant one. We used the non-recombinant approach to independently adsorb two thermophilic enzymes, GH10-XA, an endo-1,4-β-xylanase (EC 3.2.1.8) from Alicyclobacillus acidocaldarius, and GH3-XT, a β-xylosidase (EC 3.2.1.37) from Thermotoga thermarum. These enzymes catalyze, respectively, the endohydrolysis of (1-4)-β-D-xylosidic linkages of xylans and the hydrolysis of (1-4)-β-D-xylans to remove successive D-xylose residues from the non-reducing termini. We report that both purified enzymes were independently adsorbed on purified spores of B. subtilis. The adsorption was tight and both enzymes retained part of their specific activity. When spores displaying either GH10-XA or GH3-XT were mixed together, xylan was hydrolysed more efficiently than by a mixture of the two free, not spore-adsorbed, enzymes. The high total activity of the spore-bound enzymes is most likely due to a stabilization of the enzymes that, upon adsorption on the spore, remained active at the reaction conditions for longer than the free enzymes. Spore-adsorbed enzymes, collected after the two-step reaction and incubated with fresh substrate, were still active and able to continue xylan degradation. The recycling of the mixed spore-bound enzymes allowed a strong increase of xylan degradation. Our results indicate that the two-step degradation of xylans can be accomplished by mixing spores displaying either one of two required enzymes. The two-step process occurs more efficiently than with the two un-adsorbed, free enzymes and adsorbed spores can be reused for at least one other reaction round. The efficiency of the process, the reusability of the adsorbed enzymes, and the well documented robustness of spores of B. subtilis indicate the spore as a suitable platform to display enzymes for single as well as multi-step reactions.

Population dynamics in controlled unsteady-state systems: An application to the degradation of glyphosate in a sequencing batch reactor

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

Devarakonda, M.S.

1988-01-01

Control over population dynamics and organism selection in a biological waste treatment system provides an effective means of engineering process efficiency. Examples of applications of organism selection include control of filamentous organisms, biological nutrient removal, industrial waste treatment requiring the removal of specific substrates, and hazardous waste treatment. Inherently, full scale biological waste treatment systems are unsteady state systems due to the variations in the waste streams and mass flow rates of the substrates. Some systems, however, have the capacity to impose controlled selective pressures on the biological population by means of their operation. An example of such a systemmore » is the Sequencing Batch Reactor (SBR) which was the experimental system utilized in this research work. The concepts of organism selection were studied in detail for the biodegradation of a herbicide waste stream, with glyphosate as the target compound. The SBR provided a reactor configuration capable of exerting the necessary selective pressures to select and enrich for a glyphosate degrading population. Based on results for bench scale SBRs, a hypothesis was developed to explain population dynamics in glyphosate degrading systems.« less

Catalytic degradation of organophosphorous nerve agent simulants by polymer beads@graphene oxide with organophosphorus hydrolase-like activity based on rational design of functional bimetallic nuclear ligand.

PubMed

Ma, Xuejuan; Zhang, Lin; Xia, Mengfan; Zhang, Xiaohong; Zhang, Yaodong

2018-05-15

The degradation of organophosphorous nerve agents is of primary concern due to the severe toxicity of these agents. Based on the active center of organophosphorus hydrolase (OPH), a bimetallic nuclear ligand, (5-vinyl-1,3-phenylene)bis(di(1H-imidazol-2-yl) methanol) (VPIM), was designed and synthesized, which contains four imidazole groups to mimic the four histidines at OPH active center. By grafting VPIM on graphene oxide (GO) surface via polymerization, the VPIM-polymer beads@GO was produced. The obtained OPH mimics has an impressive activity in dephosphorylation reactions (turnover frequency (TOF) towards paraoxon: 2.3 s -1 ). The synergistic catalytic effect of the bimetallic Zn 2+ nuclear center and carboxyl groups on surface of GO possibly contributes to the high hydrolysis on organophosphate substrate. Thus, a biomimetic catalyst for efficient degradation of some organophosphorous nerve agent simulants, such as paraoxon and chlorpyrifos, was prepared by constructing catalytic active sites. The proposed mechanism and general synthetic strategy open new avenues for the engineering of functional GOs for biomimetic catalysts. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of molecularly imprinted polymers (MIPs) in the preconcentration of disperse red 73 dye prior to photoelectrocatalytic treatment.

PubMed

Franco, Jefferson Honorio; Aissa, Alejandra Ben; Bessegato, Guilherme Garcia; Fajardo, Laura Martinez; Zanoni, Maria Valnice Boldrin; Pividori, María Isabel; Del Pilar Taboada Sotomayor, Maria

2017-02-01

Magnetic molecularly imprinted polymers (MMIPs) have become a research hotspot due to their two important characteristics: target recognition and magnetic separation. This paper presents the preparation, characterization, and optimization of an MMIP for the preconcentration of disperse red 73 dye (DR73) and its subsequent efficient degradation by photoelectrocatalytic treatment. The MMIPs were characterized by scanning electron microscopy (SEM), which revealed homogeneous distribution of the particles. Excellent encapsulation of magnetite was confirmed by transmission electron microscopy (TEM). A study of dye binding showed that the dye was retained more selectively in the MIP, compared to the NIP. The release of DR73 from the imprinted polymers into methanol and acetic acid was analyzed by UV-Vis spectrophotometry. The extracts showed higher absorbance values for MMIP, compared to MNIP, confirming greater adsorption of dye in the MMIP material. The extracts were then subjected to photoelectrocatalytic treatment. LC-MS/MS analysis following this treatment showed that the dye was almost completely degraded. Hence, the combination of MMIP extraction and photoelectrocatalysis offers an alternative way of selectively removing an organic contaminant, prior to proceeding with its complete degradation.

Secure communications of CAP-4 and OOK signals over MMF based on electro-optic chaos.

PubMed

Ai, Jianzhou; Wang, Lulu; Wang, Jian

2017-09-15

Chaos-based secure communication can provide a high level of privacy in data transmission. Here, we experimentally demonstrate secure signal transmission over two kinds of multimode fiber (MMF) based on electro-optic intensity chaos. High-quality synchronization is achieved in an electro-optic feedback configuration. Both 5  Gbit/s carrier-less amplitude/phase (CAP-4) modulation and 10  Gbit/s on-off key (OOK) signals are recovered efficiently in electro-optic chaos-based communication systems. Degradations of chaos synchronization and communication system due to mismatch of various hardware keys are also discussed.

Efficient production of therapeutic doses of [131I]-metaiodobenzylguanidine for clinical use.

PubMed

Prabhakar, G; Mathur, Anupam; Shunmugam, G; Teje, Y D; Sachdev, S S; Sivaprasad, N

2011-01-01

[(131)I]-metaiodobenzylguanidine (mIBG) is a known radiopharmaceutical used for the treatment of neuroendocrine tumors. The development of therapeutic [(131)I]-mIBG doses at production level is highly challenging due to rapid product degradation and high radiation exposures to the production plant personnel. In the present work, a working module for the production of 10 doses (100 mCi each) in a single operation was developed following copper (I) assisted isotope exchange. The labeled product complies with the pharmaceutical specifications suitable for in-vivo patient use. Copyright © 2010 Elsevier Ltd. All rights reserved.

Helium refrigerator maintenance and reliability at the OPAL cold neutron source

NASA Astrophysics Data System (ADS)

Thiering, Russell; Taylor, David; Lu, Weijian

2012-06-01

Australia's first Cold Neutron Source (CNS) is a major asset to its nuclear research program. The CNS, and associated helium refrigerator, was commissioned in 2006 and is operated at the Open Pool Light Water nuclear Reactor (OPAL). The OPAL CNS operates a 20K, 5 kW Brayton cycle helium refrigerator. In this paper relevant experiences from helium refrigerator operation, maintenance and repair are presented along with the lessons learnt from a series of technical investigations. Turbine failure, due to volatile organic species, is discussed along with the related compressor oil degradation and oil separation efficiency.

An application of gap regenerator/expander precooled by two stage G-M refrigerator

NASA Technical Reports Server (NTRS)

Matsubara, Y.; Yasukochi, K.

1983-01-01

The degradation of regenerator effectiveness below 10K is due to the imbalance of the heat capacity of the regenerator material and helium gas as a working fluid. One of the attractive methods to increase this efficiency could be realized by a gap regenerator system regarding helium gas property. This paper describes an experiment using pressurized helium gas as a regenerator material. A two stage G-M cycle refrigerator has been used for precooling the gap regenerator system. With this method, minimum temperature below 5K has been obtained when the precooling temperature maintained at 10K.

Corn forage biological pretreatment by Trametes versicolor in a tray bioreactor.

PubMed

Planinić, Mirela; Zelić, Bruno; Čubel, Ivan; Bucić-Kojić, Ana; Tišma, Marina

2016-08-01

Trametes versicolor is a white-rot fungus known to be efficient in lignin removal due to its complex extracellular lignocellulolytic enzymatic system. Therefore, it can be used in the treatment of lignocellulose waste from agro, food, and wood industries. In a first experiment, corn forage treatment with T. versicolor was investigated in laboratory jars. In a second experiment, the process was scaled up to a tray bioreactor. In the tray bioreactor, the process of lignin degradation was improved, resulting in an increase in lignin conversion of up to 71% during seven days' treatment. © The Author(s) 2016.

Evaluation of Mismatch Losses due to Shunts in industrial Silicon Photovoltaic Modules

NASA Astrophysics Data System (ADS)

Somasundaran, P.; Shilpi, M.; Gupta, R.

2017-05-01

In order to achieve higher efficiencies in photovoltaic module technology, it is important to characterize the shunts and other defects which degrade the performance of cells and modules as well as decrease their efficiency. These shunts also affect the reliability of cells and modules. It is important to understand how much fill factor and power loss is caused by the presence of shunts in the module. Shunts not only reduce the module power output, but also affect the I-V characteristics of the cell and hence the characteristics of the shunted cells are different from those of the shunt-free cells connected in the module leading to the mismatch effect. This is an interesting effect which has been systematically investigated in the present work. Moreover, the flow of increased shunt current will give rise to increased temperature in the region of shunt, which will affect the cell and hence module performance. In the present study, the distributed diode model has been extended to the module level and applied to evaluate the electrical mismatch losses and thermal mismatch losses due to shunts in industrial Silicon PV modules.

Effects of the inclusion of a mixed Psychrotrophic bacteria strain for sewage treatment in constructed wetland in winter seasons.

PubMed

Tang, Meizhen; Li, Zhengtao; Yang, Yuewei; Chen, Junfeng; Jiang, Jie

2018-04-01

Constructed wetlands (CWs) have been used globally in wastewater treatment for years. CWs represent an efficient ecological system which is both energy-saving and low in investment for construction and operational cost. In addition, CWs also have the advantage of being easy to operate and maintain. However, the operation of CWs at northern latitudes (both mid and high) is sometimes quite demanding, due to the inhibitory effect of low temperatures that often occur in winter. To evaluate the wastewater treatment performance of a culture of mixed Psychrotrophic bacteria strains in an integrated vertical-flow CW, the removal rates of ammonia nitrogen (NH 3 -N), chemical oxygen demand (COD), nitrite nitrogen [Formula: see text], nitrate nitrogen [Formula: see text] and total phosphorus (TP) were quantified at different bacterial dosages to determine the best bacterial dosage and establish kinetic degradation models of the mixed strains. The bacterial culture was made up of Psychrobacter TM-1, Sphingobacterium TM-2 and Pseudomonas TM-3, mixed together at a volume/volume ratio of 1 : 1 : 1 (at bacterial suspension concentrations of 4.4 × 10 9  ml -1 ). Results showed that the organic pollutants (nitrogen and phosphorus) in the sewage could be efficiently removed by the culture of mixed Psychrotrophic bacteria. The optimal dosage of this mixed bacteria strain was 2.5%, and the treatment efficiency of COD, NH 3 -N, [Formula: see text], [Formula: see text], total nitrogen and TP were stable at 91.8%, 91.1%, 88.0%, 93.8%, 94.8% and 95.2%, respectively, which were 1.5, 2.0, 2.1, 1.5, 2.2 and 1.3 times those of the control group. In addition, a pseudo-first-order degradation model was a good fit for the degradation pattern observed for each of these pollutants.

Identifying and sequencing a Mycobacterium sp. strain F4 as a potential bioremediation agent for quinclorac.

PubMed

Li, Yingying; Chen, Wu; Wang, Yunsheng; Luo, Kun; Li, Yue; Bai, Lianyang; Luo, Feng

2017-01-01

Quinclorac is a widely used herbicide in rice filed. Unfortunately, quinclorac residues are phytotoxic to many crops/vegetables. The degradation of quinclorac in nature is very slow. On the other hand, degradation of quinclorac using bacteria can be an effective and efficient method to reduce its contamination. In this study, we isolated a quinclorac bioremediation bacterium strain F4 from quinclorac contaminated soils. Based on morphological characteristics and 16S rRNA gene sequence analysis, we identified strain F4 as Mycobacterium sp. We investigated the effects of temperature, pH, inoculation size and initial quinclorac concentration on growth and degrading efficiency of F4 and determined the optimal quinclorac degrading condition of F4. Under optimal degrading conditions, F4 degraded 97.38% of quinclorac from an initial concentration of 50 mg/L in seven days. Our indoor pot experiment demonstrated that the degradation products were non-phytotoxic to tobacco. After analyzing the quinclorac degradation products of F4, we proposed that F4 could employ two pathways to degrade quinclorac: one is through methylation, the other is through dechlorination. Furthermore, we reconstructed the whole genome of F4 through single molecular sequencing and de novo assembly. We identified 77 methyltransferases and eight dehalogenases in the F4 genome to support our hypothesized degradation path.

Identifying and sequencing a Mycobacterium sp. strain F4 as a potential bioremediation agent for quinclorac

PubMed Central

Li, Yingying; Chen, Wu; Wang, Yunsheng; Luo, Kun; Li, Yue; Bai, Lianyang

2017-01-01

Quinclorac is a widely used herbicide in rice filed. Unfortunately, quinclorac residues are phytotoxic to many crops/vegetables. The degradation of quinclorac in nature is very slow. On the other hand, degradation of quinclorac using bacteria can be an effective and efficient method to reduce its contamination. In this study, we isolated a quinclorac bioremediation bacterium strain F4 from quinclorac contaminated soils. Based on morphological characteristics and 16S rRNA gene sequence analysis, we identified strain F4 as Mycobacterium sp. We investigated the effects of temperature, pH, inoculation size and initial quinclorac concentration on growth and degrading efficiency of F4 and determined the optimal quinclorac degrading condition of F4. Under optimal degrading conditions, F4 degraded 97.38% of quinclorac from an initial concentration of 50 mg/L in seven days. Our indoor pot experiment demonstrated that the degradation products were non-phytotoxic to tobacco. After analyzing the quinclorac degradation products of F4, we proposed that F4 could employ two pathways to degrade quinclorac: one is through methylation, the other is through dechlorination. Furthermore, we reconstructed the whole genome of F4 through single molecular sequencing and de novo assembly. We identified 77 methyltransferases and eight dehalogenases in the F4 genome to support our hypothesized degradation path. PMID:28968436

Degradation of aniline by heterogeneous Fenton's reaction using a Ni-Fe oxalate complex catalyst.

PubMed

Liu, Yucan; Zhang, Guangming; Fang, Shunyan; Chong, Shan; Zhu, Jia

2016-11-01

A Ni-Fe oxalate complex catalyst was synthesized and characterized by means of Brunauer-Emmet-Teller (BET) method, scanning electron microscope (SEM) and X-ray photo-electron spectroscopy (XPS). The catalyst showed good catalytic activity for aniline degradation by heterogeneous Fenton's reaction, in which the synergetic index was 9.3. The effects of reaction temperature, catalyst dosage, hydrogen peroxide concentration and initial pH were investigated. Under the optimum conditions (T = 293 K, catalyst dosage = 0.2 g/L, H2O2 concentration = 4 mmol/L and initial pH = 5.4), 100% aniline could be removed within 35 min, and approximately 88% deamination efficiency was achieved in 60 min. The aniline degradation process followed the pseudo-first-order kinetic (k = 0.177 min(-1)) with activation energy (Ea) of 49.4 kJ mol(-1). Aniline could be removed in a broad initial pH (3-8) due to the excellent pH-tolerance property of the catalyst. The detected ammonium ion indicated that deamination occurred during aniline degradation. It was proposed that deamination synchronized with aniline removal, and aniline was attacked by free radicals to generate benzoquinonimine and phenol. This system is promising for the removal of aniline from water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interference of a speB 5' untranslated region partial deletion with mRNA degradation in Streptococcus pyogenes.

PubMed

Chen, Z; Mashburn-Warren, L; Merritt, J; Federle, M J; Kreth, J

2017-10-01

The 5' untranslated region (5' UTR) of an mRNA molecule embeds important determinants that modify its stability and translation efficiency. In Streptococcus pyogenes, a strict human pathogen, a gene encoding a secreted protease (speB) has a large 5' UTR with unknown functions. Here we describe that a partial deletion of the speB 5' UTR caused a general accumulation of mRNA in the stationary phase, and that the mRNA accumulation was due to retarded mRNA degradation. The phenotype was observed in several M serotypes harboring the partial deletion of the speB 5' UTR. The phenotype was triggered by the production of the truncated speB 5' UTR, but not by the disruption of the intact speB 5' UTR. RNase Y, a major endoribonuclease, was previously shown to play a central role in bulk mRNA turnover in stationary phase. However, in contrast to our expectations, we observed a weaker interaction between the truncated speB 5' UTR and RNase Y compared with the wild-type, which suggests that other unidentified RNA degrading components are required for the pleiotropic effects observed from the speB UTR truncation. Our study demonstrates how S. pyogenes uses distinct mRNA degradation schemes in exponential and stationary growth phases. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effect of storage and processing on plasmid, yeast and plant genomic DNA stability in juice from genetically modified oranges.

PubMed

Weiss, Julia; Ros-Chumillas, Maria; Peña, Leandro; Egea-Cortines, Marcos

2007-01-30

Recombinant DNA technology is an important tool in the development of plant varieties with new favourable features. There is strong opposition towards this technology due to the potential risk of horizontal gene transfer between genetically modified plant material and food-associated bacteria, especially if genes for antibiotic resistance are involved. Since horizontal transfer efficiency depends on size and length of homologous sequences, we investigated the effect of conditions required for orange juice processing on the stability of DNA from three different origins: plasmid DNA, yeast genomic DNA and endogenous genomic DNA from transgenic sweet orange (C. sinensis L. Osb.). Acidic orange juice matrix had a strong degrading effect on plasmid DNA which becomes apparent in a conformation change from supercoiled structure to nicked, linear structure within 5h of storage at 4 degrees C. Genomic yeast DNA was degraded during exposure to acidic orange juice matrix within 4 days, and also the genomic DNA of C. sinensis suffered degradation within 2 days of storage as indicated by amplification results from transgene markers. Standard pasteurization procedures affected DNA integrity depending on the method and time used. Our data show that the current standard industrial procedures to pasteurize orange juice as well as its acidic nature causes a strong degradation of both yeast and endogenous genomic DNA below sizes reported to be suitable for horizontal gene transfer.

Incomplete proteasomal degradation of green fluorescent proteins in the context of tandem fluorescent protein timers

PubMed Central

Khmelinskii, Anton; Meurer, Matthias; Ho, Chi-Ting; Besenbeck, Birgit; Füller, Julia; Lemberg, Marius K.; Bukau, Bernd; Mogk, Axel; Knop, Michael

2016-01-01

Tandem fluorescent protein timers (tFTs) report on protein age through time-dependent change in color, which can be exploited to study protein turnover and trafficking. Each tFT, composed of two fluorescent proteins (FPs) that differ in maturation kinetics, is suited to follow protein dynamics within a specific time range determined by the maturation rates of both FPs. So far, tFTs have been constructed by combining slower-maturing red fluorescent proteins (redFPs) with the faster-maturing superfolder green fluorescent protein (sfGFP). Toward a comprehensive characterization of tFTs, we compare here tFTs composed of different faster-maturing green fluorescent proteins (greenFPs) while keeping the slower-maturing redFP constant (mCherry). Our results indicate that the greenFP maturation kinetics influences the time range of a tFT. Moreover, we observe that commonly used greenFPs can partially withstand proteasomal degradation due to the stability of the FP fold, which results in accumulation of tFT fragments in the cell. Depending on the order of FPs in the timer, incomplete proteasomal degradation either shifts the time range of the tFT toward slower time scales or precludes its use for measurements of protein turnover. We identify greenFPs that are efficiently degraded by the proteasome and provide simple guidelines for the design of new tFTs. PMID:26609072

Introducing saccharic acid as an efficient iron chelate to enhance photo-Fenton degradation of organic contaminants.

PubMed

Subramanian, Gokulakrishnan; Madras, Giridhar

2016-11-01

The identification of iron chelates that can enhance photo-Fenton degradation is of great interest in the field of advanced oxidation process. Saccharic acid (SA) is a polyhydroxy carboxylic acid and completely non-toxic. Importantly, it can effectively bind Fe(III) as well as induce photoreduction of Fe(III). Despite having these interesting properties, the effect of SA on photo-Fenton degradation has not been studied. Herein, we demonstrate the first assessment of SA as an iron chelate in photo-Fenton process using methylene blue (MB) as a model organic contaminant. Our results demonstrate that SA has the ability to (i) enhance the photo-Fenton degradation of MB by about 11 times at pH 4.5 (ii) intensify photochemical reduction of Fe(III) to Fe(II) by about 17 times and (iii) accelerate the rate of consumption of H 2 O 2 in photo-Fenton process by about 5 times (iv) increase the TOC reduction by about 2 times and (v) improve the photo-Fenton degradation of MB in the presence of a variety of common inorganic ions and organic matter. The influential properties of SA on photo-Fenton degradation is attributed to the efficient photochemical reduction of Fe(III) via LMCT (ligand to metal charge transfer reaction) to Fe(II), which then activated H 2 O 2 to generate OH and accelerated photo-Fenton degradation efficiency. Moreover, the effect of operational parameters such as oxidant: contaminant (H 2 O 2 : MB) ratio, catalyst: contaminant (Fe(III)SA: MB) ratio, Fe(III): SA stoichiometry and pH on the degradation of MB by photo-Fenton in the presence of SA is demonstrated. Importantly, SA assisted photo-Fenton caused effective degradation of MB and 4-Chlorophenol under natural sunlight irradiation in natural water matrix. The findings strongly support SA as a deserving iron chelate to enhance photo-Fenton degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Decolorization of azo dyes Orange G using hydrodynamic cavitation coupled with heterogeneous Fenton process.

PubMed

Cai, Meiqiang; Su, Jie; Zhu, Yizu; Wei, Xiaoqing; Jin, Micong; Zhang, Haojie; Dong, Chunying; Wei, Zongsu

2016-01-01

The present work demonstrates the application of the combination of hydrodynamic cavitation (HC) and the heterogeneous Fenton process (HF, Fe(0)/H2O2) for the decolorization of azo dye Orange G (OG). The effects of main affecting operation conditions such as the inlet fluid pressure, initial concentration of OG, H2O2 and zero valent iron (ZVI), the fixed position of ZVI, and medium pH on decolorization efficiency were discussed with guidelines for selection of optimum parameters. The results revealed that the acidic conditions are preferred for OG decolorizaiton. The decolorization rate increased with increasing H2O2 and ZVI concentration and decreased with increasing OG initial concentration. Besides, the decolorization rate was strongly dependent on the fixed position of ZVI. The analysis results of degradation products using liquid chromatography-ESI-TOF mass spectrometry revealed that the degradation mechanism of OG proceeds mainly via reductive cleavage of the azo linkage due to the attack of hydroxyl radical. The present work has conclusively established that the combination of HC and HF can be more energy efficient and gives higher decolorization rate of OG as compared with HC and HF alone. Copyright © 2015 Elsevier B.V. All rights reserved.

Pyrrolic-N-doped graphene oxide/Fe2O3 mesocrystal nanocomposite: Efficient charge transfer and enhanced photo-Fenton catalytic activity

NASA Astrophysics Data System (ADS)

Liu, Bing; Tian, Lihong; Wang, Ran; Yang, Jinfeng; Guan, Rong; Chen, Xiaobo

2017-11-01

Though α-Fe2O3 has attracted much attention in photocatalytic or Fenton-catalytic degradation of organic contaminants, its performance is still unsatisfactory due to fast recombination of electrons and holes in photocatalytic process and the difficult conversion of Fe(II) and Fe(III) in Fenton reaction. Herein, a pyrrolic N-doped graphene oxide/Fe2O3 mesocrystal (NG-Fe2O3) nanocomposite with good distribution is synthesized by a simple solvothermal method and adjusting the oxygen-containing groups on graphene oxide. The morphology of NG-Fe2O3 contributes to a relatively large BET surface area and an intimate contact between NG and Fe2O3. These two important factors along with the excellent electro-conductivity of pyrrolic-N doped GO result in the efficient separation of electron-hole pairs and fast conversion of Fe(II)and Fe(III) in photo-Fenton synergistic reaction. Thus, a remarkably improved photo-Fenton catalytic activity of NG-Fe2O3 is obtained. The degrading rate on methyl blue increases by 1.5 times and the conversion rate of glyphosate increases by 2.3 times under visible light irradiation, compared to pristine α-Fe2O3 mesocrystals.

Effectiveness of incentives for agri-environment measure in Mediterranean degraded and eroded vineyards

NASA Astrophysics Data System (ADS)

Galati, Antonino; Gristina, Luciano; Crescimanno, Maria; Barone, Ettore; Novara, Agata

2015-04-01

The evaluation of the economic damage caused by soil erosion assumes great importance. It serves to increase awareness of the problem among farmers and policy makers. Moreover, it can promote the implementation of conservative measures at the field and basin level by spurring the development of more sustainable soil management practices. In the present study we have developed a new approach to evaluate the incentive for the adoption of Agri-Environment Measure (AEM) in Mediterranean degraded and eroded vineyards. In order to estimate this incentive, the replacement cost and the loss of income are calculated under two different soil management such as Conventional Tillage (CT) and Cover crop (AEM). Our findings show that the incentive could range between the loss of income due to AEM adoption and ecosystem service benefit (RCCT - RC AEM). In the case of study the incentive ranged between 315 € ha-1 (loss of income) and 1,087.86 € ha-1 (Ecosystem service benefit). Within this range, the incentive amount is determined according to efficiency criteria taking into account the morphological conditions of the territory in which operate the farms. Moreover, a conceptual model on the public spending efficiency has been developed to allocate the incentives where the economic return in term of ecosystem service is higher.

Ligand removal and photo-activation of CsPbBr3 quantum dots for enhanced optoelectronic devices.

PubMed

Moyen, Eric; Kanwat, Anil; Cho, Sinyoung; Jun, Haeyeon; Aad, Roy; Jang, Jin

2018-05-10

Perovskite quantum dots have recently emerged as a promising light source for optoelectronic applications. However, integrating them into devices while preserving their outstanding optical properties remains challenging. Due to their ionic nature, perovskite quantum dots are extremely sensitive and degrade on applying the simplest processes. To maintain their colloidal stability, they are surrounded by organic ligands; these prevent efficient charge carrier injection in devices and have to be removed. Here we report on a simple method, where a moderate thermal process followed by exposure to UV in air can efficiently remove ligands and increase the photo-luminescence of the room temperature synthesized perovskite quantum dot thin films. Annealing is accompanied by a red shift of the emission wavelength, usually attributed to the coalescence and irreversible degradation of the quantum dots. We show that it is actually related to the relaxation of the quantum dots upon the ligand removal, without the creation of non-radiative recombining defects. The quantum dot surface, as devoid of ligands, is subsequently photo-oxidized and smoothened upon exposure to UV in air, which drastically enhances their photo-luminescence. This adequate combination of treatments improves by more than an order of magnitude the performances of perovskite quantum dot light emitting diodes.

Zeolite Y encapsulated with Fe-TiO2 for ultrasound-assisted degradation of amaranth dye in water.

PubMed

Alwash, Atheel Hassan; Abdullah, Ahmad Zuhairi; Ismail, Norli

2012-09-30

A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe(2)O(3) due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO(2) content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2 g/L, 20 mmol/100 mL of H(2)O(2) and initial dye concentration of 10 mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation and characterization of photocatalytic carbon dots-sensitized electrospun titania nanostructured fibers

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

Li, Haopeng; Zhu, Yihua, E-mail: yhzhu@ecust.edu.cn; Cao, Huimin

2013-02-15

Graphical abstract: Display Omitted Highlights: ► The TiO{sub 2}-CDs nanostructured fibers are fabricated by using APS combining the electrospinning TiO{sub 2} nanostructured fibers and CDs. ► The CD can work as a photosensitizer in the degradation of rhodamine B under visible light irradiation. ► The TiO{sub 2}-CDs nanostructured fibers exhibit enhanced photocatalytic efficiency and can be easily handled and recycled. -- Abstract: The carbon dots (CDs) are new functional carbon-aceous materials. Compared to conventional dye molecules and semiconductor quantum dots, CDs are superior in chemical inertness and low toxicity. The TiO{sub 2}-CDs nanostructured fibers were fabricated by combining the electrospinningmore » technique and reflux method. Compared with the pure TiO{sub 2} nanostructured fibers and P25, the TiO{sub 2}-CDs nanostructured fibers exhibited enhanced photocatalytic efficiency of photodegradation of rhodamine B (RhB) under visible light irradiation. The enhanced photocatalytic activity of TiO{sub 2}-CDs nanostructured fibers could be attributed to the presence of CDs embedded in TiO{sub 2} nanostructured fibers. The CD can work as a photosensitizer in the degradation. Furthermore, the TiO{sub 2}-CDs nanostructured fibers could be easily handled and recycled due to their one-dimensional nanostructural property.« less

Maintaining protein homeostasis: early and late endosomal dual recycling for the maintenance of intracellular pools of the plasma membrane protein Chs3

PubMed Central

Arcones, Irene; Sacristán, Carlos; Roncero, Cesar

2016-01-01

The major chitin synthase activity in yeast cells, Chs3, has become a paradigm in the study of the intracellular traffic of transmembrane proteins due to its tightly regulated trafficking. This includes an efficient mechanism for the maintenance of an extensive reservoir of Chs3 at the trans-Golgi network/EE, which allows for the timely delivery of the protein to the plasma membrane. Here we show that this intracellular reservoir of Chs3 is maintained not only by its efficient AP-1–mediated recycling, but also by recycling through the retromer complex, which interacts with Chs3 at a defined region in its N-terminal cytosolic domain. Moreover, the N-terminal ubiquitination of Chs3 at the plasma membrane by Rsp5/Art4 distinctly labels the protein and regulates its retromer-mediated recycling by enabling Chs3 to be recognized by the ESCRT machinery and degraded in the vacuole. Therefore the combined action of two independent but redundant endocytic recycling mechanisms, together with distinct labels for vacuolar degradation, determines the final fate of the intracellular traffic of the Chs3 protein, allowing yeast cells to regulate morphogenesis, depending on environmental constraints. PMID:27798229

A novel device for hazardous substances degradation based on double-cavitating-jets impingement: Parameters optimization and efficiency assessment.

PubMed

Tao, Yuequn; Cai, Jun; Huai, Xiulan; Liu, Bin

2017-08-05

Hydrodynamic cavitation is an effective advanced oxidation process. But sometimes it cannot obtain satisfactory treatment efficiency by using hydrodynamic cavitation individually, so it is necessary to introduce intensive methods. Based on double-cavitating-jets impingement, this paper presents a novel device that has advantages of strong heat and mass transfer and efficient chemical reactions. Based on the device, a series of experimental investigations on degradation of a basic dye, i.e. Rhodamine B were carried out. Significant Rhodamine B removal from aqueous solution was observed during 2h treatment and the degradation reaction conformed to pseudo-first-order kinetics. The synergetic effects between double-cavitating-jets impingement and Fenton chemistry on simultaneous degradation of Rhodamine B were confirmed. Both single-variable experiments and orthogonal experiments were carried out to study the effects of initial hydrogen peroxide, ferrous sulfate and Rhodamine B concentrations and the optimum conditions were found out. Effects of jet inlet pressure in the range of 6-12MPa and solution pH value in the range of 2-8 were also investigated. The cavitation yield was evaluated to assess the energy efficiency. The present treatment scheme showed advantages in terms of reducing the demand of hydrogen peroxide concentration and enhancing the treatment efficiency in large scale operation. Copyright © 2017 Elsevier B.V. All rights reserved.

Aging of biomixtures: Effects on carbofuran removal and microbial community structure.

PubMed

Castro-Gutiérrez, Víctor; Masís-Mora, Mario; Diez, María Cristina; Tortella, Gonzalo R; Rodríguez-Rodríguez, Carlos E

2017-02-01

The aim of this work was to determine the efficiency of a straw/compost/soil biomixture for pesticide depuration during its aging and continuous use, for a period of over a year, based on its capacity to remove carbofuran (CFN), while simultaneously monitoring the variations in microbial community structure. Successive CFN spikings were applied in the biomixture at 6-week intervals, and the removal efficiency was determined 48 h post-application. Initially, only a discrete degradation performance was observed (9.9%), but one CFN application was sufficient to induce efficient elimination (>88.5%) of the pesticide at subsequent influxes for a period of over 6 months. A statistically significant reduction on CFN removal efficiency after this time was detected, reaching levels similar to the fresh-prepared biomixture (14.8%) at the end of the experiment. Simultaneous DGGE analyses showed only modest changes on microbial community patterns through time for both, bacteria and fungi. The clustering of genetic fingerprints in chronological groups corresponding to significantly different CFN degradation efficiencies indicates that biomixture aging changes not only the composition of microbial communities, but also their suitability to engage in pesticide degradation. Periodic substitution of straw/compost/soil biomixture in biopurification systems or regular provision of easily-degradable organic substrates should be considered to maintain an adequate depuration capacity on this system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sustaining 1,2-Dichloroethane Degradation in Nanoscale Zero-Valent Iron induced Fenton system by using Sequential H2O2 Addition at Natural pH

NASA Astrophysics Data System (ADS)

Phenrat, T.; Le, T. S. T.

2017-12-01

1,2-Dichloroethane (1,2-DCA) is a prevalent subsurface contaminant found in groundwater and soil around the world. Nanoscale zero-valent iron (NZVI) is a promising in situ remediation agent for chlorinated organics. Nevertheless, 1,2-DCA is recalcitrant to reductive dechlorination using NZVI. Chemical oxidation using Fenton's reaction with conventional Fe2+ is a valid option for 1,2-DCA remediation with a major technical challenge, i.e. aquifer acidification is needed to maintain Fe2+ for catalytic reaction. In this work, NZVI Fenton's process at neutral pH was applied to degrade 1,2-DCA at high concentration (2,000 mg/L) representing dissolved 1,2-DCA concentration close to non-aqueous phase liquid source zone. Instead of using acidification to maintain dissolved Fe2+ concentration, NZVI Fenton's process is self-catalytic based on oxidative dissolution of NZVI in the present of H2O2. Interfacial H+ is produced at NZVI surface to provide appropriate local pH which continuously releases Fe2+ for Fenton's reaction. Approximately, 87% of 1,2-DCA was degraded at neutral pH with the pseudo first-order rate constant of 0.98 hour-1 using 10 g/L of NZVI and 200 mM of H2O2. However, the reaction was prohibited quickly within 3 hours presumably due to the rapid depletion of H2O2. The application of sequential H2O2 addition provided a better approach to prevent rapid inhibition via controlling the H2O2 concentration in the system to be sufficient but not excess, thus resulting in the higher degradation efficiency (the pseudo first-order rate constant of 0.49 hour-1 and 99 % degradation in 8 hours). Using NZVI with sequential H2O2 addition was also successful in degrading 1,2-DCA sorbed on to soil, yielding 99% removal of 1,2-DCA within 16 hours at the rate constant of 0.23 hour-1, around two times slower than in the system without soil presumably due to rate-limited 1,2-DCA desorption from soil. Mechanistic understanding of how sequential addition of H2O2, in comparison to the simultaneous H2O2 addition, can sustain oxidative degradation of 1,2-DCA was also proposed in addition to the investigation of NZVI reusability in three consecutive 1, 2-DCA degradation cycles.

Degradation in finite-harmonic subcarrier demodulation

NASA Technical Reports Server (NTRS)

Feria, Y.; Townes, S.; Pham, T.

1995-01-01

Previous estimates on the degradations due to a subcarrier loop assume a square-wave subcarrier. This article provides a closed-form expression for the degradations due to the subcarrier loop when a finite number of harmonics are used to demodulate the subcarrier, as in the case of the buffered telemetry demodulator. We compared the degradations using a square wave and using finite harmonics in the subcarrier demodulation and found that, for a low loop signal-to-noise ratio, using finite harmonics leads to a lower degradation. The analysis is under the assumption that the phase noise in the subcarrier (SC) loop has a Tikhonov distribution. This assumption is valid for first-order loops.

Resource-use efficiencies of three indigenous tree species planted in resource islands created by shrubs: implications for reforestation of subtropical degraded shrublands

Treesearch

Nan Liu; Qinfeng Guo

2012-01-01

Shrub resource islands are characterized by resources accumulated shrubby areas surrounded by relative barren soils. This research aims to determine resource-use efficiency of native trees species planted on shrub resource islands, and to determine how the planted trees may influence the resource islands in degraded shrublands in South China. Shrub (Rhodomyrtus...

Power Efficient Plasma Technique for Rapid Water Sterilization

NASA Astrophysics Data System (ADS)

Hershcovitch, Ady

2015-11-01

Water especially good quality drinking water is a dwindling resource for significant segments of the world population. The BBC quoted this article (http://www.ft.com/cms/s/2/8e42bdc8-0838-11e4-9afc-00144feab7de.html) for a claim that water shortage is a bigger problem than climate change. One option for increasing the water supply is to recycle waste and polluted water by inexpensive, environmentally friendly methods. First steps involve filtrations while the last step is water disinfection. Presently disinfection is done chemically and/or UV radiation. Some chemicals cannot be used in large quantity due to residual toxicity, while UV disinfection systems consume a great deal electricity. Plasmas in water are very attractive for water sterilization due to UV radiation, ozone, etc. generation inside the water volume. Commercially available devices like NK-03 Blue Ballast System are used aboard ships for water purification. But, presently utilized plasmas: glow, pulsed arcs are not power efficient. Vortex stabilized plasmas, which are power efficient, can even degrade medications (antibiotics) advancing the state-of-the-art by orders of magnitude, especially when combined with electron beams. Disinfection scheme will be presented. Work supported by Contract No. DE-AC02-98CH1-886 with the US DOE.

Cylindrospermopsin degradation in sediments--the role of temperature, redox conditions, and dissolved organic carbon.

PubMed

Klitzke, Sondra; Fastner, Jutta

2012-04-01

One possible consequence of increasing water temperatures due to global warming in middle Europe is the proliferation of cylindrospermopsin-producing species from warmer regions. This may lead to more frequent and increased cylindrospermopsin (CYN) concentrations in surface waters. Hence, efficient elimination of CYN is important where contaminated surface waters are used as a resource for drinking water production via sediment passage. Sediments are often characterized by a lack of oxygen and low temperature (i.e. approx. 10 °C). The presence of dissolved organic carbon (DOC) is not only known to enhance but also to retard contaminant degradation by influencing the extent of lag phases. So far CYN degradation has only been investigated under oxic conditions and at room temperature. Therefore, the aim of our experiments was to understand CYN degradation, focusing on the effects of i) anoxic conditions, ii) low temperature (i.e. 10 °C) in comparison to room temperature (23±4 °C) and iii) DOC on lag phases. We used two natural sandy sediments (virgin and preconditioned) and surface water to conduct closed-loop column experiments. Anoxic conditions either inhibited CYN degradation completely or retarded CYN breakdown in comparison to oxic conditions (T(1/2) (oxic)=2.4 days, T(1/2) (anoxic)=23.6 days). A decrease in temperature from 20 °C to 10 °C slowed down degradation rates by a factor of 10. The presence of DOC shortened lag phases in virgin sediments at room temperature but induced a lag phase in preconditioned sediments at 10 °C, indicating potential substrate competition. These results show that information on physico-chemical conditions in sediments is crucial to assess the risk of CYN breakthrough. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development and Utilization of Host Materials for White Phosphorescent Organic Light-Emitting Diodes

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

Tang, Ching; Chen, Shaw

Our project was primarily focused on the MYPP 2015 goal for white phosphorescent organic devices (PhOLEDs or phosphorescent organic light-emitting diodes) for solid-state lighting with long lifetimes and high efficiencies. Our central activity was to synthesize and evaluate a new class of host materials for blue phosphors in the PhOLEDs, known to be a weak link in the device operating lifetime. The work was a collaborative effort between three groups, one primarily responsible for chemical design and characterization (Chen), one primarily responsible for device development (Tang) and one primarily responsible for mechanistic studies and degradation analysis (Rothberg). The host materialsmore » were designed with a novel architecture that chemically links groups with good ability to move electrons with those having good ability to move “holes” (positive charges), the main premise being that we could suppress the instability associated with physical separation and crystallization of the electron conducting and hole conducting materials that might cause the devices to fail. We found that these materials do prevent crystallization and that this will increase device lifetimes but that efficiencies were reduced substantially due to interactions between the materials creating new low energy “charge transfer” states that are non-luminescent. Therefore, while our proposed strategy could in principle improve device lifetimes, we were unable to find a materials combination where the efficiency was not substantially compromised. In the course of our project, we made several important contributions that are peripherally related to the main project goal. First, we were able to prepare the proposed new family of materials and develop synthetic routes to make them efficiently. These types of materials that can transport both electrons and holes may yet have important roles to play in organic device technology. Second we developed an important new method for controlling the deposition profile of material so that arbitrary concentration gradients can be implemented in layers with mixed composition. These concentration profiles are known to increase device efficiency and longevity and we confirmed that experimentally. Third, we investigated a new method for analyzing degradation in devices using mass spectrometry to look for degradation products. We showed that these methods are not simple to interpret unambiguously and need to be used with caution.« less

Isolation and characterization of phenol degrading bacterium strain Bacillus thuringiensis J20 from olive waste in Palestine.

PubMed

Ereqat, Suheir I; Abdelkader, Ahmad A; Nasereddin, Abedelmajeed F; Al-Jawabreh, Amer O; Zaid, Taher M; Letnik, Ilya; Abdeen, Ziad A

2018-01-02

This study aimed at isolation of phenol degrading bacteria from olive mill wastes in Palestine. The efficiency of phenol removal and factors affecting phenol degradation were investigated. A bacterial strain (J20) was isolated from solid olive mill waste and identified as Bacillus thuringiensis based on standard morphological, biochemical characteristics and 16SrRNA sequence analysis. The strain was able to grow in a phenol concentration of 700 mg/L as the sole carbon and energy source. The culture conditions showed a significant impact on the ability of these cells to remove phenol. This strain exhibited optimum phenol degradation performance at pH 6.57 and 30 °C . Under the optimized conditions, this strain could degrade 88.6% of phenol (700 mg/L) within 96 h when the initial cell density was OD 600 0.2. However, the degradation efficiency could be improved from about 88% to nearly 99% by increasing the cell density. Immobilization of J20 was carried out using 4% sodium alginate. Phenol degradation efficiency of the immobilized cells of J20 was higher than that of the free cells, 100% versus 88.6% of 700 mg/L of phenol in 120 h, indicating the improved tolerance of the immobilized cells toward phenol toxicity. The J20 was used in detoxifying crude OMWW, phenolic compounds levels were reduced by 61% compared to untreated OMWW after five days of treatment. Hence, B. thuringiensis-J20 can be effectively used for bioremediation of phenol-contaminated sites in Palestine. These findings may lead to new biotechnological applications for the degradation of phenol, related to olive oil production.

The spatial proximity effect of beta-glucosidase and cellulosomes on cellulose degradation.

PubMed

Li, Xiaoyi; Xiao, Yan; Feng, Yingang; Li, Bin; Li, Wenli; Cui, Qiu

2018-08-01

Low-cost saccharification is one of the key bottlenecks hampering the further application of lignocellulosic biomass. Clostridium thermocellum is a naturally ideal cellulose degrading bacterium armed with cellulosomes, which are multienzyme complexes that are capable of efficiently degrading cellulose. However, under controlled condition, the inhibition effect of hydrolysate cellobiose severely restricts the hydrolytic ability of cellulosomes. Although the addition of beta-glucosidase (Bgl) could effectively relieve this inhibition, the spatial proximity effect of Bgl and cellulosomes on cellulose degradation is still unclear. To address this issue, free Bgl from Caldicellulosiruptor sp. F32 (CaBglA), carbohydrate-binding module (CBM) fused CaBglA (CaBglA-CBM) and cellulosomal type II cohesin module (CohII) fused to CaBglA (CaBglA-CohII) were successfully constructed, and their enzymatic activities, binding abilities and saccharification efficiencies were systematically investigated in vitro and in vivo. In vivo, with the adjacency of CaBglA to cellulosomes, the saccharification efficiency of microcrystalline cellulose increased from 40% to 50%. For the pretreated wheat straw, the degradation rate of the combination of cells and the CaBglA-CohII or the CaBglA-CBM was as efficient as that of the free CaBglA (approximately 60%). This study demonstrated that the proximity of CaBglA to cellulosomes had a positive effect on microcrystalline cellulose but not on pretreated wheat straw, which may result from the nonproductive adsorption of lignin and the decreased thermostability of CaBglA-CBM and CaBglA-CohII compared to that of CaBglA. The above results will contribute to the design of cost-effective Bgls for industrial cellulose degradation. Copyright © 2018. Published by Elsevier Inc.

Leachate from Municipal Waste Landfill and Its Natural Degradation—A Case Study of Zubří, Zlín Region

PubMed Central

Václavík, Vojtěch; Ondrašiková, Ivana; Dvorský, Tomáš; Černochová, Kateřina

2016-01-01

This work deals with the natural degradation of leachate from an old reclaimed landfill by means of a biological pond. Hamra is a municipal waste landfill with a limited formation of leachate, which has already been reclaimed. Leachate in this location is disposed of using natural biogeochemical method, and it is subsequently discharged into a surface stream. The main issue dealt with here is the long-term effectiveness of natural degradation of leachate and the limits of its use. The solutions of these fundamental questions took advantage of a database of analytical assessments collected during a long-term monitoring of the landfill site. The primary degradation trends and the long-term development have been revealed and described on the basis of these assessments. The main benefit of the biological pond is the dilution of the dominant contaminants, especially of inorganic character. In the case of ammonium ions, they show nitrification caused by their transition from the reduction into oxidizing environment. From a long term point of view, the disadvantage of natural degradation of leachate can be seen in the gradual reduction in efficiency due to the concentration of the substances or an undesired growth of water plants, which can be successfully eliminated, for example, by means of targeted aeration and by maintaining vegetation in the pond and its surroundings. The biological potential of the locality is very favorable and, despite its anthropogenic load, it creates a location with suitable living conditions for many water animals and plants. That is why it can be concluded that the efficiency of the natural biochemical cleaning elements can be considered as sufficient, taking into account the nature of the deposited waste, the quantity and quality of leachate, as well as the climate character of the locality. PMID:27598181

Solar-chemical treatment of groundwater contaminated with petroleum at gas station sites: ex situ remediation using solar/TiO(2) photocatalysis and Solar Photo-Fenton.

PubMed

Cho, Ii-Hyoung; Kim, Young-Gyu; Yang, Jae-Kyu; Lee, Nae-Hyun; Lee, Seung-Mok

2006-01-01

Groundwater samples contaminated by BTEX (benzene, toluene, ethylbenzene, xylene isomers and TPHs (total petroleum hydrocarbons) were treated with advanced oxidation processes (AOPs), such as TiO(2) photocatalysis and Fe(2+)/H(2)O(2) exposed to solar light (37 degrees N and 128 degrees E) with an average intensity of 1.7 mW/cm(2) at 365 nm. These AOP processes showed feasibility in the treatment of groundwater contaminated with BTEX, TPH and TOC (Total Organic Carbon). Outdoor field tests showed that the degradation efficiency of each contaminant was higher in the Fe(2+)/H(2)O(2) system without solar light compared to the TiO(2)/solar light and H(2)O(2)/solar light systems. However, the TiO(2)/solar light and the Fe(2+)/H(2)O(2)/solar light systems showed significantly enhanced efficiencies in the degradation of BTEX, TPH and TOC with the additional use of H(2)O(2). Near complete degradation of BTEX and TPH was observed within 2 and 4 hrs, respectively, however, that of TOC was slower. Without pretreatment of the groundwater, fouling of the TiO(2), due to the ionic species present, was observed within 1 hr of operation, which resulted in the inhibition of further BTEX, TPH and TOC destruction. The degradation rate of n-alkanes with carbon numbers ranging from C10 to C15 was relatively greater than that of n-alknaes with carbon numbers ranging from C16 to C20. From this work, the AOP process (Fe(2+)/H(2)O(2)/solar light and TiO(2)/H(2)O(2)/solar light) illuminated with solar light was identified as an effective ex situ technique in the remediation of groundwater contaminated with petroleum.

Characterization of Cu(II) and Cd(II) resistance mechanisms in Sphingobium sp. PHE-SPH and Ochrobactrum sp. PHE-OCH and their potential application in the bioremediation of heavy metal-phenanthrene co-contaminated sites.

PubMed

Chen, Chen; Lei, Wenrui; Lu, Min; Zhang, Jianan; Zhang, Zhou; Luo, Chunling; Chen, Yahua; Hong, Qing; Shen, Zhenguo

2016-04-01

Soil that is co-contaminated with heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) is difficult to bioremediate due to the ability of toxic metals to inhibit PAH degradation by bacteria. We demonstrated the resistance mechanisms to Cu(II) and Cd(II) of two newly isolated strains of Sphingobium sp. PHE-SPH and Ochrobactrum sp. PHE-OCH and further tested their potential application in the bioremediation of HM-phenanthrene (PhA) co-contaminated sites. The PHE-SPH and PHE-OCH strains tolerated 4.63 and 4.34 mM Cu(II) and also showed tolerance to 0.48 and 1.52 mM Cd(II), respectively. Diverse resistance patterns were detected between the two strains. In PHE-OCH cells, the maximum accumulation of Cu(II) occurred in the cell wall, while the maximum accumulation was in the cytoplasm of PHE-SPH cells. This resulted in a sudden suppression of growth in PHE-OCH and a gradual inhibition in PHE-SPH as the concentration of Cu(II) increased. Organic acid production was markedly higher in PHE-OCH than in PHE-SPH, which may also have a role in the resistance mechanisms, and contributes to the higher Cd(II) tolerance of PHE-OCH. The factors involved in the absorption of Cu(II) or Cd(II) in PHE-SPH and PHE-OCH were identified as proteins and carbohydrates by Fourier transform infrared (FT-IR) spectroscopy. Furthermore, both strains showed the ability to efficiently degrade PhA and maintained this high degradation efficiency under HM stress. The high tolerance to HMs and the PhA degradation capacity make Sphingobium sp. PHE-SPH and Ochrobactrum sp. PHE-OCH excellent candidate organisms for the bioremediation of HM-PhA co-contaminated sites.

Viterbi decoding for satellite and space communication.

NASA Technical Reports Server (NTRS)

Heller, J. A.; Jacobs, I. M.

1971-01-01

Convolutional coding and Viterbi decoding, along with binary phase-shift keyed modulation, is presented as an efficient system for reliable communication on power limited satellite and space channels. Performance results, obtained theoretically and through computer simulation, are given for optimum short constraint length codes for a range of code constraint lengths and code rates. System efficiency is compared for hard receiver quantization and 4 and 8 level soft quantization. The effects on performance of varying of certain parameters relevant to decoder complexity and cost are examined. Quantitative performance degradation due to imperfect carrier phase coherence is evaluated and compared to that of an uncoded system. As an example of decoder performance versus complexity, a recently implemented 2-Mbit/sec constraint length 7 Viterbi decoder is discussed. Finally a comparison is made between Viterbi and sequential decoding in terms of suitability to various system requirements.

H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts.

PubMed

Agbe, Henry; Raza, Nadeem; Dodoo-Arhin, David; Chauhan, Aditya; Kumar, Ramachandran Vasant

2018-04-01

Ag 3 PO 4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag 3 PO 4 photo-corrodes if electron accepter such as AgNO 3 is not used as scavenger. Synthesis of efficient Ag 3 PO 4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag 3 PO 4 , whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag 3 PO 4 is converted to Ag 0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag 3 PO 4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H 2 O 2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag 3 PO 4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag 3 PO 4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO 2 , and some of TiO 2 composites tested in this work.

A new five-coordinated copper compound for efficient degradation of methyl orange and Congo red in the absence of UV-visible radiation.

PubMed

Han, Li-Juan; Kong, Ya-Jie; Yan, Ting-Jiang; Fan, Lu-Tong; Zhang, Qi; Zhao, Hua-Jun; Zheng, He-Gen

2016-11-22

A new copper-based coordination compound Cu 2 (2,2'-bipy) 2 (pfbz) 4 (1) (where 2,2'-bipy = 2,2'-bipyridine; pfbz = pentafluorobenzoate), was hydrothermally synthesized and structurally characterized. Compound 1 having a binuclear structure consists of two copper cations and two oxygen atoms alternately in a plane square arrangement. In the presence of very small amounts of H 2 O 2 , the catalytic properties of compound 1 for the degradation of methyl orange (MO) are excellent in the absence of UV-visible radiation. Moreover, compound 1 presents suitable properties for degradation of Congo red (CR). Our results indicated that the five-coordinated copper compound, 1, will be a promising candidate for efficient degradation of organic dyes.

Impact of composting strategies on the degradation of nonylphenol in sewage sludge.

PubMed

Zheng, Guodi; Chen, Tongbin; Yu, Jie; Gao, Ding; Shen, Yujun; Niu, Mingjie; Liu, Hongtao

2015-12-01

Nonylphenol can be present in sewage sludge, and this can limit the use of the sewage sludge to amend soil. Composting is one of the most efficient and economical methods of making sewage sludge stable and harmless. The nonylphenol degradation rates during composting with added bulking agents and with aeration applied were studied. Three organic bulking agents (sawdust, corn stalk, and mushroom residue) were added to sewage sludge, and the effects of the bulking agents used and the amount added on nonylphenol degradation were determined. The highest apparent nonylphenol degradation rate (71.6%) was found for sewage sludge containing 20% mushroom residue. The lowest apparent nonylphenol degradation rate (22.5%) was found for sewage sludge containing 20% sawdust. The temperature of the composting pile of sewage sludge containing 20% sawdust became too high for nonylphenol to be efficiently degraded, and the apparent nonylphenol degradation rate was lower than was found for sewage sludge containing 10% sawdust. Increasing the ventilating time from 5 to 15 min increased the apparent nonylphenol degradation rate from 19.7 to 41.6%. Using appropriate aerobic conditions facilitates the degradation of nonylphenol in sewage sludge, decreasing the risks posed by sewage sludge applied to land. Adding too much of a bulking agent can decrease the amount of the nonylphenol degraded. Increasing the ventilating time and the amount of air supplied can increase the amount of nonylphenol degraded even if doing so causes the composting pile temperature to remain low.

A simple method for decomposition of peracetic acid in a microalgal cultivation system.

PubMed

Sung, Min-Gyu; Lee, Hansol; Nam, Kibok; Rexroth, Sascha; Rögner, Matthias; Kwon, Jong-Hee; Yang, Ji-Won

2015-03-01

A cost-efficient process devoid of several washing steps was developed, which is related to direct cultivation following the decomposition of the sterilizer. Peracetic acid (PAA) is known to be an efficient antimicrobial agent due to its high oxidizing potential. Sterilization by 2 mM PAA demands at least 1 h incubation time for an effective disinfection. Direct degradation of PAA was demonstrated by utilizing components in conventional algal medium. Consequently, ferric ion and pH buffer (HEPES) showed a synergetic effect for the decomposition of PAA within 6 h. On the contrary, NaNO3, one of the main components in algal media, inhibits the decomposition of PAA. The improved growth of Chlorella vulgaris and Synechocystis PCC6803 was observed in the prepared BG11 by decomposition of PAA. This process involving sterilization and decomposition of PAA should help cost-efficient management of photobioreactors in a large scale for the production of value-added products and biofuels from microalgal biomass.

High-Efficiency Plug-and-Play Source of Heralded Single Photons

NASA Astrophysics Data System (ADS)

Montaut, Nicola; Sansoni, Linda; Meyer-Scott, Evan; Ricken, Raimund; Quiring, Viktor; Herrmann, Harald; Silberhorn, Christine

2017-08-01

Reliable generation of single photons is of key importance for fundamental physical experiments and to demonstrate quantum protocols. Waveguide-based photon-pair sources have shown great promise in this regard due to their large spectral tunability, high generation rates, and long temporal coherence of the photon wave packet. However, integrating such sources with fiber-optic networks often results in a strong degradation of performance. We answer this challenge by presenting an alignment-free source of photon pairs in the telecommunications band that maintains heralding efficiency >50 % even after fiber pigtailing, photon separation, and pump suppression. The source combines this outstanding performance in heralding efficiency with a compact, stable, and easy-to-use "plug-and-play" package: one simply connects a laser to the input and detectors to the output, and the source is ready to use. This high performance can be achieved even outside the lab without the need for alignment which makes the source extremely useful for any experiment or demonstration needing heralded single photons.

Nanotubular Toughening Inclusions

NASA Technical Reports Server (NTRS)

Park, Cheol (Inventor); Working, Dennis C. (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

2017-01-01

Conventional toughening agents are typically rubbery materials or small molecular weight molecules, which mostly sacrifice the intrinsic properties of a matrix such as modulus, strength, and thermal stability as side effects. On the other hand, high modulus inclusions tend to reinforce elastic modulus very efficiently, but not the strength very well. For example, mechanical reinforcement with inorganic inclusions often degrades the composite toughness, encountering a frequent catastrophic brittle failure triggered by minute chips and cracks. Thus, toughening generally conflicts with mechanical reinforcement. Carbon nanotubes have been used as efficient reinforcing agents in various applications due to their combination of extraordinary mechanical, electrical, and thermal properties. Moreover, nanotubes can elongate more than 20% without yielding or breaking, and absorb significant amounts of energy during deformation, which enables them to also be an efficient toughening agent, as well as excellent reinforcing inclusion. Accordingly, an improved toughening method is provided by incorporating nanotubular inclusions into a host matrix, such as thermoset and thermoplastic polymers or ceramics without detrimental effects on the intrinsic physical properties of the matrix.

Nanotubular Toughening Inclusions

NASA Technical Reports Server (NTRS)

Park, Cheol (Inventor); Working, Dennis C. (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

2015-01-01

Conventional toughening agents are typically rubbery materials or small molecular weight molecules, which mostly sacrifice the intrinsic properties of a matrix such as modulus, strength, and thermal stability as side effects. On the other hand, high modulus inclusions tend to reinforce elastic modulus very efficiently, but not the strength very well. For example, mechanical reinforcement with inorganic inclusions often degrades the composite toughness, encountering a frequent catastrophic brittle failure triggered by minute chips and cracks. Thus, toughening generally conflicts with mechanical reinforcement. Carbon nanotubes have been used as efficient reinforcing agents in various applications due to their combination of extraordinary mechanical, electrical, and thermal properties. Moreover, nanotubes can elongate more than 20% without yielding or breaking, and absorb significant amounts of energy during deformation, which enables them to also be an efficient toughening agent, as well as excellent reinforcing inclusion. Accordingly, an improved toughening method is provided by incorporating nanotubular inclusions into a host matrix, such as thermoset and thermoplastic polymers or ceramics without detrimental effects on the matrix's intrinsic physical properties.

Electricity generation from rapeseed straw hydrolysates using microbial fuel cells.

PubMed

Jablonska, Milena A; Rybarczyk, Maria K; Lieder, Marek

2016-05-01

Rapeseed straw is an attractive fuel material for microbial fuel cells (MFCs) due to its high content of carbohydrates (more than 60% carbohydrates). This study has demonstrated that reducing sugars can be efficiently extracted from raw rapeseed straw by combination of hydrothermal pretreatment and enzymatic hydrolysis followed by utilization as a fuel in two-chamber MFCs for electrical power generation. The most efficient method of saccharification of this lignocellulosic biomass (17%) turned out hydrothermal pretreatment followed by enzymatic hydrolysis. Electricity was produced using hydrolysate concentrations up to 150 mg/dm(3). The power density reached 54 mW/m(2), while CEs ranged from 60% to 10%, corresponding to the initial reducing sugar concentrations of 10-150 mg/dm(3). The COD degradation rates based on charge calculation increased from 0.445 g COD/m(2)/d for the hydrolysate obtained with the microwave treatment to 0.602 g COD/m(2)/d for the most efficient combination of hydrothermal treatment followed by enzymatic hydrolysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Towards efficient and cost-effective inverted hybrid organic solar cells using inorganic semiconductor in the active layer

NASA Astrophysics Data System (ADS)

Imran, M.; Ikram, M.; Dilpazir, S.; Nafees, M.; Ali, S.; Geng, J.

2017-11-01

The article investigates the effects of NiO (p-type) and TiO2 (n-type) nanoparticles (NPs) on the performance of poly(3-hexylthiophene) (P3HT) and (phenyl-C61-butyric acid methylester) (PCBM) based devices with an inverse geometry. Various weight ratios of these nanoparticles were mixed in the polymer solution using 1,2-dichlorobenzene as solvent. An optimal amount of NPs-doped active layer exhibited higher power conversion efficiency (PCE) of 3.85% as compared to the reference cell, which exhibited an efficiency of 3.40% under white light illumination intensity of 100 mW/cm2. Enhanced PCE originates from increased film roughness and light harvesting due to increased absorption range upon mixing an optimal amount of NPs in the organic-based active layer. Further addition of NiO and TiO2 concentration relative to PCBM resulted in significant agglomeration of nanoparticles leading to degraded device parameters.

Method of radiation degradation of PTFE under vacuum conditions

NASA Astrophysics Data System (ADS)

Korenev, Sergey

2004-09-01

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

Crystal growth for high-efficiency silicon solar cells workshop: Summary

NASA Technical Reports Server (NTRS)

Dumas, K. A.

1985-01-01

The state of the art in the growth of silicon crystals for high-efficiency solar cells are reviewed, sheet requirements are defined, and furture areas of research are identified. Silicon sheet material characteristics that limit cell efficiencies and yields were described as well as the criteria for the ideal sheet-growth method. The device engineers wish list to the material engineer included: silicon sheet with long minority carrier lifetime that is uniform throughout the sheet, and which doesn't change during processing; and sheet material that stays flat throughout device processing, has uniform good mechanical strength, and is low cost. Impurities in silicon solar cells depreciate cell performance by reducing diffusion length and degrading junctions. The impurity behavior, degradation mechanisms, and variations in degradation threshold with diffusion length for silicon solar cells were described.

Searching for life on Mars: degradation of surfactant solutions used in organic extraction experiments.

PubMed

Court, Richard W; Sims, Mark R; Cullen, David C; Sephton, Mark A

2014-09-01

Life-detection instruments on future Mars missions may use surfactant solutions to extract organic matter from samples of martian rocks. The thermal and radiation environments of space and Mars are capable of degrading these solutions, thereby reducing their ability to dissolve organic species. Successful extraction and detection of biosignatures on Mars requires an understanding of how degradation in extraterrestrial environments can affect surfactant performance. We exposed solutions of the surfactants polysorbate 80 (PS80), Zonyl FS-300, and poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) to elevated radiation and heat levels, combined with prolonged storage. Degradation was investigated by measuring changes in pH and electrical conductivity and by using the degraded solutions to extract a suite of organic compounds spiked onto grains of the martian soil simulant JSC Mars-1. Results indicate that the proton fluences expected during a mission to Mars do not cause significant degradation of surfactant compounds. Solutions of PS80 or PDMSHEPMS stored at -20 °C are able to extract the spiked standards with acceptable recovery efficiencies. Extraction efficiencies for spiked standards decrease progressively with increasing temperature, and prolonged storage at 60°C renders the surfactant solutions ineffective. Neither the presence of ascorbic acid nor the choice of solvent unequivocally alters the efficiency of extraction of the spiked standards. Since degradation of polysorbates has the potential to produce organic compounds that could be mistaken for indigenous martian organic matter, the polysiloxane PDMSHEPMS may be a superior choice of surfactant for the exploration of Mars.

Applications of Cu{sub 2}O octahedral particles on ITO glass in photocatalytic degradation of dye pollutants under a halogen tungsten lamp

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

Zhai, Wei; Sun, Fengqiang, E-mail: fqsun@scnu.edu.cn; Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, South China Normal University

2013-11-15

Graphical abstract: - Highlights: • Photocatalytic activity of Cu{sub 2}O octahedral microcrystals on ITO glass was studied. • They showed high abilities in degradation of methylene blue in the presence of H{sub 2}O{sub 2}. • H{sub 2}O{sub 2} amount could affect the degradation efficiency. • Such particles could be easily recycled and still kept high activity. • Many dye pollutants and their mixtures could be efficiently degraded. - Abstract: Cu{sub 2}O octahedral microcrystals were prepared on the ITO glass by galvanostatic electrodeposition in CuSO{sub 4} solution with poly(vinylpryrrolidone) as the surfactant. By controlling the electrodeposition time, the microcrystals could bemore » randomly distributed on the ITO glass and separated from each other, resulting in as many as possible (1 1 1) crystalline planes were exposed. Such microcrystals immobilized on ITO glass were employed in photodegradation of dye pollutants in the presence of H{sub 2}O{sub 2} under a 150 W halogen tungsten lamp. The photodegradation of methylene blue was taken as an example to evaluate the photocatalytic activities of the octahedral Cu{sub 2}O microcrystals. Effects of electrodeposition time and H{sub 2}O{sub 2} amount on the degradation efficiency was discussed, giving the optimum conditions and the corresponding degradation mechanism. The catalyst showed high ability in degradation of methylene blue, methyl orange, rhodamine B, eosin B and their mixtures under identical conditions.« less

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.

Geotechnical properties of municipal solid waste at different phases of biodegradation

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

Reddy, Krishna R., E-mail: kreddy@uic.edu; Hettiarachchi, Hiroshan, E-mail: hiroshan@ltu.edu; Gangathulasi, Janardhanan, E-mail: jganga2@uic.edu

Highlights: > Degraded synthetic municipal solid waste (MSW) anaerobically in controlled bench-scale reactors. > Performed laboratory tests to determine geotechnical properties of MSW at different phases of degradation. > Hydraulic conductivity decreased by two orders of magnitude due to degradation. > Compression ratio reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. > Friction angle reduced, but cohesion increased with degradation. - Abstract: This paper presents the results of laboratory investigation conducted to determine the variation of geotechnical properties of synthetic municipal solid waste (MSW) at different phases of degradation. Synthetic MSW samples were preparedmore » based on the composition of MSW generated in the United States and were degraded in bioreactors with leachate recirculation. Degradation of the synthetic MSW was quantified based on the gas composition and organic content, and the samples exhumed from the bioreactor cells at different phases of degradation were tested for the geotechnical properties. Hydraulic conductivity, compressibility and shear strength of initial and degraded synthetic MSW were all determined at constant initial moisture content of 50% on wet weight basis. Hydraulic conductivity of synthetic MSW was reduced by two orders of magnitude due to degradation. Compression ratio was reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. Direct shear tests showed that the fresh and degraded synthetic MSW exhibited continuous strength gain with increase in horizontal deformation, with the cohesion increased from 1 kPa for fresh MSW to 16-40 kPa for degraded MSW and the friction angle decreased from 35{sup o} for fresh MSW to 28{sup o} for degraded MSW. During the triaxial tests under CU condition, the total strength parameters, cohesion and friction angle, were found to vary from 21 to 57 kPa and 1{sup o} to 9{sup o}, respectively, while the effective strength parameters, cohesion and friction angle varied from 18 to 56 kPa and from 1{sup o} to 11{sup o}, respectively. Similar to direct shear test results, as the waste degrades an increase in cohesion and slight decrease in friction angle was observed. Decreased friction angle and increased cohesion with increased degradation is believed to be due to the highly cohesive nature of the synthetic MSW. Variation of synthetic MSW properties from this study also suggests that significant changes in geotechnical properties of MSW can occur due to enhanced degradation induced by leachate recirculation.« less

Mechanisms of cardiac hypertrophy in canine volume overload

NASA Technical Reports Server (NTRS)

Matsuo, T.; Carabello, B. A.; Nagatomo, Y.; Koide, M.; Hamawaki, M.; Zile, M. R.; McDermott, P. J.

1998-01-01

This study tested whether the modest hypertrophy that develops in dogs in response to mitral regurgitation is due to a relatively small change in the rate of protein synthesis or, alternatively, is due to a decreased rate of protein degradation. After 3 mo of severe experimental mitral regurgitation, the left ventricular (LV) mass-to-body weight ratio increased by 23% compared with baseline values. This increase in LV mass occurred with a small, but not statistically significant, increase in the fractional rate of myosin heavy chain (MHC) synthesis (Ks), as measured using continuous infusion with [3H]leucine in dogs at 2 wk, 4 wk, and 3 mo after creation of severe mitral regurgitation. Translational efficiency was unaffected by mitral regurgitation as measured by the distribution of MHC mRNA in polysome gradients. Furthermore, there was no detectable increase in translational capacity as measured by either total RNA content or the rate of ribosome formation. These data indicate that translational mechanisms that accelerate the rate of cardiac protein synthesis are not responsive to the stimulus of mitral regurgitation. Most of the growth after mitral regurgitation was accounted for by a decrease in the fractional rate of protein degradation, calculated by subtracting fractional rates of protein accumulation at each time point from the corresponding Ks values. We conclude that 1) volume overload produced by severe mitral regurgitation does not trigger substantial increases in the rate of protein synthesis and 2) the modest increase in LV mass results primarily from a decrease in the rate of protein degradation.

Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition.

PubMed

Jothiramalingam, R; Wang, M K

2007-08-17

The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R2 and standard error. The goodness to the linear fit was observed for Elovich model with high R2 (>or=0.9477) value.

Ferrous iron/peroxymonosulfate oxidation as a pretreatment for ceramic ultrafiltration membrane: Control of natural organic matter fouling and degradation of atrazine.

PubMed

Cheng, Xiaoxiang; Liang, Heng; Ding, An; Tang, Xiaobin; Liu, Bin; Zhu, Xuewu; Gan, Zhendong; Wu, Daoji; Li, Guibai

2017-04-15

Ferrous iron/peroxymonosulfate (Fe(II)/PMS) oxidation was employed as a pretreatment method for ultrafiltration process to control membrane fouling caused by natural organic matter, including humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA), and their mixture (HA-SA-BSA). To evaluate the mechanism of fouling mitigation, the effects of Fe(II)/PMS pretreatment on the characteristics of feed water were examined. The degradation of atrazine (ATZ) was also investigated and the species of generated radicals were preliminarily determined. Under the test exposure (15 and 50 μM), Fe(II)/PMS pretreatment effectively mitigated membrane fouling caused by HA, SA and HA-SA-BSA mixture, and the performance improved with the increase of Fe(II) or PMS dose; whereas aggravated BSA fouling at lower doses and fouling alleviation was observed only at a higher dose (50/50 μΜ). The fouling mitigation was mainly attributed to the effective reduction of organic loadings by coagulation with in-situ formed Fe(III). Its performance was comparable or even slightly higher than single coagulation with Fe(III), most likely due to the oxidation by Fe(II)/PMS process. Fe(II)/PMS oxidation showed better performance in reducing DOC and UV 254 , fluorescence intensities of fluorescent components and UV-absorbing compounds than single coagulation. In addition, Fe(II)/PMS pretreatment was efficient in ATZ degradation due to the generation of sulfate and hydroxyl radicals, whereas coagulation was ineffective to remove it. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical Degradation of Rhodamine B over Ti/SnO2-Sb Electrode.

PubMed

Maharana, Dusmant; Niu, Junfeng; Gao, Ding; Xu, Zesheng; Shi, Jianghong

2015-04-01

Electrochemical degradation of rhodamine B (C28H31ClN2O3) over Ti/SnO2-Sb anode was investigated in a rectangular cell. The degradation reaction follows pseudo-first-order kinetics. The degradation efficiency of rhodamine B attained >90.0% after 20 minutes of electrolysis at initial concentrations of 5 to 200 mg/L at a constant current density of 20 mA/cm2 with a 10 mmol/L Na2SO4 supporting electrolyte solution. Rhodamine B (50 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9 and 86.7%, respectively, at the optimal conditions after 30 minutes of electrolysis. The results showed that the energy efficiency of rhodamine B (50 mg/L) degradation at the optimal current densities from 2 to 30 mA/cm2 were 23.2 to 84.6 Wh/L, whereas the electrolysis time for 90% degradation of rhodamine B with Ti/SnO2-Sb anode was 36.6 and 7.3 minutes, respectively. The electrochemical method can be an advisable option for the treatment of dyes such as rhodamine B in wastewater.

Advanced oxidation processes on doxycycline degradation: monitoring of antimicrobial activity and toxicity.

PubMed

Spina-Cruz, Mylena; Maniero, Milena Guedes; Guimarães, José Roberto

2018-05-08

Advanced oxidation processes (AOPs) have been highly efficient in degrading contaminants of emerging concern (CEC). This study investigated the efficiency of photolysis, peroxidation, photoperoxidation, and ozonation at different pH values to degrade doxycycline (DC) in three aqueous matrices: fountain, tap, and ultrapure water. More than 99.6% of DC degradation resulted from the UV/H 2 O 2 and ozonation processes. Also, to evaluate the toxicity of the original solution and throughout the degradation time, antimicrobial activity tests were conducted using Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, and acute toxicity test using the bioluminescent marine bacterium (Vibrio fischeri). Antimicrobial activity reduced as the drug degradation increased in UV/H 2 O 2 and ozonation processes, wherein the first process only 6 min was required to reduce 100% of both bacteria activity. In ozonation, 27.7 mg L -1 of ozone was responsible for reducing 100% of the antimicrobial activity. When applied the photoperoxidation process, an increase in the toxicity occurred as the high levels of degradation were achieved; it means that toxic intermediates were formed. The ozonated solutions did not present toxicity.

Glyphosate contaminated soil remediation by atmospheric pressure dielectric barrier discharge plasma and its residual toxicity evaluation.

PubMed

Wang, Tiecheng; Ren, Jingyu; Qu, Guangzhou; Liang, Dongli; Hu, Shibin

2016-12-15

Glyphosate was one of the most widely used herbicides in the world. Remediation of glyphosate-contaminated soil was conducted using atmospheric pressure dielectric barrier discharge (DBD) plasma. The feasibility of glyphosate degradation in soil was explored, and the soil leachate toxicity after remediation was assessed via a seed germination test. The experimental results showed that approximately 93.9% of glyphosate was degraded within 45min of DBD plasma treatment with an energy yield of 0.47gkWh -1 , and the degradation process fitted the first-order kinetic model. Increasing the discharge voltage and decreasing the organic matter content of the soil were both found to facilitate glyphosate degradation. There existed appropriate soil moisture to realize high glyphosate degradation efficiency. Glyphosate mineralization was confirmed by changes of total organic carbon (TOC), chemical oxygen demand (COD), PO 4 3- and NO 3 - . The degradation intermediates including glycine, aminomethylphosphonic acid, acetic acid, formic acid, PO 4 3- and NO 3 - , CO 2 and CO were observed. A possible pathway for glyphosate degradation in the soil using this system was proposed. Based on the soil leachate toxicity test using wheat seed germination, the soil did not exhibit any hazardous effects following high-efficiency glyphosate degradation. Copyright © 2016 Elsevier B.V. All rights reserved.

Breeding of in-situ Petroleum Degrading Bacteria in Hangzhou Bay and evaluating for the In-situ repair effect

NASA Astrophysics Data System (ADS)

Lan, Ru; Lin, Hai; Qiao, Bing; Dong, Yingbo; Zhang, Wei; Chang, Wen

2018-02-01

In this paper, the restoration behaviour of the in-situ microorganisms in seawater and sediments to the marine accident oil spill was researched. The experimental study on the breeding of in-situ petroleum-degrading bacteria in the seawater and sediments of Hangzhou Bay and the restoration of oil spill were carried out. Making use of the reinforced microbial flora, combined with physical and chemical methods in field environment, petroleum degrading and restoration experiment were performed, the effect of the breeding of in-situ degrading bacteria was evaluated, and the standard process of in-situ bacteria sampling, laboratory screening, domestication and degradation efficiency testing were formed. This study laid a foundation for further evaluation of the advantages and disadvantages for the petroleum-degrading bacteria of Hangzhou Bay during the process of in-situ restoration. The results showed that in-situ microbes of Hangzhou Bay could reach the growth peak in 5 days with the suitable environmental factors and sufficient nutrient elements, and the degradation efficiency could reach 65.2% (or 74.8% after acclimation). And also the microbes could adapt to the local sea water and environmental conditions, with a certain degree of degradation. The research results could provide parameter support for causal judgment and quantitative assessment of oil spill damage.

Asymmetric underlap optimization of sub-10nm finfets for realizing energy-efficient logic and robust memories

NASA Astrophysics Data System (ADS)

Akkala, Arun Goud

Leakage currents in CMOS transistors have risen dramatically with technology scaling leading to significant increase in standby power consumption. Among the various transistor candidates, the excellent short channel immunity of Silicon double gate FinFETs have made them the best contender for successful scaling to sub-10nm nodes. For sub-10nm FinFETs, new quantum mechanical leakage mechanisms such as direct source to drain tunneling (DSDT) of charge carriers through channel potential energy barrier arising due to proximity of source/drain regions coupled with the high transport direction electric field is expected to dominate overall leakage. To counter the effects of DSDT and worsening short channel effects and to maintain Ion/ Ioff, performance and power consumption at reasonable values, device optimization techniques are necessary for deeply scaled transistors. In this work, source/drain underlapping of FinFETs has been explored using quantum mechanical device simulations as a potentially promising method to lower DSDT while maintaining the Ion/ Ioff ratio at acceptable levels. By adopting a device/circuit/system level co-design approach, it is shown that asymmetric underlapping, where the drain side underlap is longer than the source side underlap, results in optimal energy efficiency for logic circuits in near-threshold as well as standard, super-threshold operating regimes. In addition, read/write conflict in 6T SRAMs and the degradation in cell noise margins due to the low supply voltage can be mitigated by using optimized asymmetric underlapped n-FinFETs for the access transistor, thereby leading to robust cache memories. When gate-workfunction tuning is possible, using asymmetric underlapped n-FinFETs for both access and pull-down devices in an SRAM bit cell can lead to high-speed and low-leakage caches. Further, it is shown that threshold voltage degradation in the presence of Hot Carrier Injection (HCI) is less severe in asymmetric underlap n-FinFETs. A lifetime projection is carried out assuming that HCI is the major degradation mechanism and it is shown that a 3.4x improvement in device lifetime is possible over symmetric underlapped n-FinFET.

Fabrication of PAN@TiO2/Ag nanofibrous membrane with high visible light response and satisfactory recyclability for dye photocatalytic degradation

NASA Astrophysics Data System (ADS)

Shi, Yongzheng; Yang, Dongzhi; Li, Yuan; Qu, Jin; Yu, Zhong-Zhen

2017-12-01

Although TiO2-based photocatalysts have exhibited a great potential for degradation of organic pollutants, it is still necessary to simultaneously enhance their visible-light-driven photocatalytic efficiency and physical recyclability. Herein, highly efficient, visible-light-driven photocatalytically active, and recyclable nanofibrous membranes with thin TiO2/Ag heterojunction layer are prepared using electrospun polyacrylonitrile (PAN) nanofibrous membrane as the substrate. By regulating the concentration and hydrolysis process of Ti precursors, TiO2 nanoparticles steadily grow on the PAN nanofibers with high-specific surface area to form a continuous mesoporous shell with the thickness of 20 nm for efficient degradation of organic pollutants. Furthermore, to form a stable heterojunction structure, Ag nanoparticles are deposited on the TiO2 surface by using dopamine as a binder and reductant. The presence of Ag nanoparticles leads to an obvious red-shift from 380 nm to 490 nm, which improves the utilization efficiency of visible light, and reduces the electron/hole recombination rate simultaneously. The resulting PAN@TiO2/Ag membranes hold enhanced photocatalytic activity for methylene blue degradation within 1 h under visible light irradiation, and satisfactory recyclability, which endow them with a great potential for adsorption and photocatalytic applications.