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Sample records for atrezijas slimniekiem pec

  1. PATHOGEN EQUIVALENCY COMMITTEE (PEC)

    EPA Science Inventory

    The U.S. Environmental Protection Agency created the PEC in 1985 to make recommendations to EPA and State managers on the equivalency of unproven sewage sludge disinfection technologies/processes to either a Process to Significantly Reduce Pathogens (PSRP) or a Process to Further...

  2. ACTIVE PEC APPLICATIONS, THE PEC WEBSITE, AND SLUDGE STABILITY RESEARCH

    EPA Science Inventory

    Since it's creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing novel sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether these novel technolog...

  3. INTRODUCING THE FIRST EVER PEC WEBSITE

    EPA Science Inventory

    Since it's creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing novel sludge disinfection technologies and their ability to protect human health and the environment. The PEC is charged to make recommendations on whether these novel technologies provide eq...

  4. Automated Geometry assisted PEC for electron beam direct write nanolithography

    SciTech Connect

    Ocola, Leonidas E.; Gosztola, David J.; Rosenmann, Daniel; Lopez, Gerald Gabriel

    2015-12-01

    Nanoscale geometry assisted proximity effect correction (NanoPEC) is demonstrated to improve PEC for nanoscale structures over standard PEC, in terms of feature sharpness for sub-100 nm structures. The method was implemented onto an existing commercially available PEC software. Plasmonic arrays of crosses were fabricated using regular PEC and NanoPEC, and optical absorbance was measured. Results confirm that the improved sharpness of the structures leads to increased sharpness in the optical absorbance spectrum features. We also demonstrated that this method of PEC is applicable to arbitrary shaped structures beyond crosses.

  5. Definition of a consensus DNA-binding site for PecS, a global regulator of virulence gene expression in Erwinia chrysanthemi and identification of new members of the PecS regulon.

    PubMed

    Rouanet, Carine; Reverchon, Sylvie; Rodionov, Dmitry A; Nasser, William

    2004-07-16

    In Erwinia chrysanthemi, production of pectic enzymes is modulated by a complex network involving several regulators. One of them, PecS, which belongs to the MarR family, also controls the synthesis of various other virulence factors, such as cellulases and indigoidine. Here, the PecS consensus-binding site is defined by combining a systematic evolution of ligands by an exponential enrichment approach and mutational analyses. The consensus consists of a 23-base pair palindromic-like sequence (C(-11)G(-10)A(-9)N(-8)W(-7)T(-6)C(-5)G(-4)T(-3)A(-2))T(-1)A(0)T(1)(T(2)A(3)C(4)G(5)A(6)N(7)N(8)N(9)C(10)G(11)). Mutational experiments revealed that (i) the palindromic organization is required for the binding of PecS, (ii) the very conserved part of the consensus (-6 to 6) allows for a specific interaction with PecS, but the presence of the relatively degenerated bases located apart significantly increases PecS affinity, (iii) the four bases G, A, T, and C are required for efficient binding of PecS, and (iv) the presence of several binding sites on the same promoter increases the affinity of PecS. This consensus is detected in the regions involved in PecS binding on the previously characterized target genes. This variable consensus is in agreement with the observation that the members of the MarR family are able to bind various DNA targets as dimers by means of a winged helix DNA-binding motif. Binding of PecS on a promoter region containing the defined consensus results in a repression of gene transcription in vitro. Preliminary scanning of the E. chrysanthemi genome sequence with the consensus revealed the presence of strong PecS-binding sites in the intergenic region between fliE and fliFGHIJKLMNOPQR which encode proteins involved in the biogenesis of flagellum. Accordingly, PecS directly represses fliE expression. Thus, PecS seems to control the synthesis of virulence factors required for the key steps of plant infection.

  6. Training Paraprofessionals to Implement the Picture Exchange Communication System (PECS)

    ERIC Educational Resources Information Center

    Sloman, Glenn Matthew

    2010-01-01

    Based on Skinner's "Verbal Behavior" (1957), the picture exchange communication system (PECS) was designed to teach children with autism functional verbal behavior. Much research has demonstrated the effectiveness and efficiency of PECS in building verbal behavior. However, because PECS training is typically presented in a group format and later…

  7. PecS Is a Global Regulator of the Symptomatic Phase in the Phytopathogenic Bacterium Erwinia chrysanthemi 3937▿ †

    PubMed Central

    Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

    2008-01-01

    Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to pathogenicity and to a group of genes concerned with evading host defenses. Among the targets are the genes encoding plant cell wall-degrading enzymes and secretion systems and the genes involved in flagellar biosynthesis, biosurfactant production, and the oxidative stress response, as well as genes encoding toxin-like factors such as NipE and hemolysin-coregulated proteins. In vitro experiments demonstrated that PecS interacts with the regulatory regions of five new targets: an oxidative stress response gene (ahpC), a biosurfactant synthesis gene (rhlA), and genes encoding exported proteins related to other plant-associated bacterial proteins (nipE, virK, and avrL). The pecS mutant provokes symptoms more rapidly and with more efficiency than the wild-type strain, indicating that PecS plays a critical role in the switch from the asymptomatic phase to the symptomatic phase. Based on this, we propose that the temporal regulation of the different groups of genes required for the asymptomatic phase and the symptomatic phase is, in part, the result of a gradual modulation of PecS activity triggered during infection in response to changes in environmental conditions emerging from the interaction between both partners. PMID:18790868

  8. Molecules to Materials for PEC Water Splitting

    SciTech Connect

    Neale, N. R.; Ruddy, D. A.; Lee, K.; Seabold, J. A.; Deutsch, T. G.; Dukovic, G.

    2013-01-01

    Advances in heterogeneous catalysis are driven by the formation of structure-property relationships at solid-liquid and solid-gaseous interfaces. The establishment of these relationships relies on cooperative research efforts on several fronts: prediction and analysis using high-level theoretical models, the development of new synthetic methods to prepare specific solid-state compositions and structures, new analytical methods to identify the active site and define interfacial properties, and mechanistic analysis of functioning catalysts. However, customized materials that allow for fine control of the interfacial properties at solid-liquid boundaries represent difficult synthetic targets. We have been investigating molecular synthons as precursors to advanced materials to address this challenge. In this presentation, we will discuss (1) the chemistry of molecular inorganic complexes, (2) their conversion to mixed-metal oxides, and (3) structure-property relationships of the resulting oxides relevant to PEC water splitting.

  9. The Unusual Suspects: Myths and Misconceptions Associated with PECS

    ERIC Educational Resources Information Center

    Bondy, Andy

    2012-01-01

    The Picture Exchange Communication System (PECS) is an alternative/augmentative communication protocol designed to help children and adults with autism and related disabilities to engage in functional communication. The protocol was developed over a number of years and was based on Skinner's analysis of verbal behavior. Publications about the…

  10. Social-Communicative Effects of the Picture Exchange Communication System (PECS) in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Lerna, Anna; Esposito, Dalila; Conson, Massimiliano; Russo, Luigi; Massagli, Angelo

    2012-01-01

    Background: The Picture Exchange Communication System (PECS) is a common treatment choice for non-verbal children with autism. However, little empirical evidence is available on the usefulness of PECS in treating social-communication impairments in autism. Aims: To test the effects of PECS on social-communicative skills in children with autism,…

  11. Using the picture exchange communication system (PECS) with children with autism: assessment of PECS acquisition, speech, social-communicative behavior, and problem behavior.

    PubMed Central

    Charlop-Christy, Marjorie H; Carpenter, Michael; Le, Loc; LeBlanc, Linda A; Kellet, Kristen

    2002-01-01

    The picture exchange communication system (PECS) is an augmentative communication system frequently used with children with autism (Bondy & Frost, 1994; Siegel, 2000; Yamall, 2000). Despite its common clinical use, no well-controlled empirical investigations have been conducted to test the effectiveness of PECS. Using a multiple baseline design, the present study examined the acquisition of PECS with 3 children with autism. In addition, the study examined the effects of PECS training on the emergence of speech in play and academic settings. Ancillary measures of social-communicative behaviors and problem behaviors were recorded. Results indicated that all 3 children met the learning criterion for PECS and showed concomitant increases in verbal speech. Ancillary gains were associated with increases in social-communicative behaviors and decreases in problem behaviors. The results are discussed in terms of the provision of empirical support for PECS as well as the concomitant positive side effects of its use. PMID:12365736

  12. Nanoscale geometry assisted proximity effect correction (NanoPEC) for electron beam direct write nanolithography.

    SciTech Connect

    Ocola, L. E.

    2009-11-01

    Nanoscale geometry assisted proximity effect correction is presented for nanoscale structures and the results clearly show improvements in feature sharpness down to 20 nm structures. The design rule is simple to implement onto existing PEC software and enables implementation of PEC down to the resolution limits of electron beam lithography.

  13. The Picture Exchange Communication System (PECS): What Do the Data Say?

    ERIC Educational Resources Information Center

    Sulzer-Azaroff, Beth; Hoffman, Anne O.; Horton, Catherine B.; Bondy, Andrew; Frost, Lori

    2009-01-01

    Originally designed to enable young children with autism lacking functional communication to initiate requests and to describe what they observed, the Picture Exchange Communication System (PECS) has been the subject of an ever-expanding body of research and development. Thirty-four peer-reviewed published reports on PECS are analyzed in this…

  14. Experimental Evaluation of the Training Structure of the Picture Exchange Communication System (PECS)

    ERIC Educational Resources Information Center

    Cummings, Anne R.; Carr, James E.; LeBlanc, Linda A.

    2012-01-01

    The Picture Exchange Communication System (PECS) is a picture-based alternative communication method that is widely accepted and utilized with individuals with disabilities. Although prior studies have examined the clinical efficacy of PECS, none have experimentally evaluated its manualized training structure. We experimentally evaluated the…

  15. Evaluation of pharmaceuticals in surface water: reliability of PECs compared to MECs.

    PubMed

    Celle-Jeanton, Hélène; Schemberg, Dimitri; Mohammed, Nabaz; Huneau, Frédéric; Bertrand, Guillaume; Lavastre, Véronique; Le Coustumer, Philippe

    2014-12-01

    Due to the current analytical processes that are not able to measure all the pharmaceutical molecules and to the high costs and the consumption of time to sample and analyze PhACs, models to calculate Predicted Environmental Concentrations (PECs) have been developed. However a comparison between MECs and PECs, taking into account the methods of calculations and peculiarly the parameters included in the calculation (consumption data, pharmacokinetic parameters, elimination rate in STPs and in the environment), is necessary to assess the validity of PECs. MEC variations of sixteen target PhACs [acetaminophen (ACE), amlodipine (AML), atenolol (ATE), caffeine (CAF), carbamazepine (CAR), doxycycline (DOX), epoxycarbamazepine (EPO), fluvoxamine (FLU), furosemide (FUR), hydrochlorothiazide (HYD), ifosfamide (IFO), losartan (LOS), pravastatin (PRA), progesterone (PROG), ramipril (RAM), trimetazidine (TRI)] have been evaluated during one hydrological cycle, from October 2011 to October 2012 and compared to PECs calculated by using an adaptation of the models proposed by Heberer and Feldmann (2005) and EMEA (2006). Comparison of PECs and MECS has been achieved for six molecules: ATE, CAR, DOX, FUR, HYD and PRA. DOX, FUR and HYD present differences between PECs and MECs on an annual basis but their temporal evolutions follow the same trends. PEC evaluation for these PhACs could then be possible but need some adjustments of consumption patterns, pharmacokinetic parameters and/or mechanisms of (bio)degradation. ATE, CAR and PRA are well modeled; PECs can then be used as reliable estimation of concentrations without any reserve.

  16. Reducing PEC uncertainty in coastal zones: a case study on carbamazepine, oxcarbazepine and their metabolites.

    PubMed

    Fenet, Hélène; Arpin-Pont, Lauren; Vanhoutte-Brunier, Alice; Munaron, Dominique; Fiandrino, Annie; Martínez Bueno, Maria-Jesus; Boillot, Clotilde; Casellas, Claude; Mathieu, Olivier; Gomez, Elena

    2014-07-01

    Concentrations of the antiepileptic drugs carbamazepine (Cbz), oxcarbazepine (OxCz) and their main metabolites were predicted in a wastewater treatment plant (WTP) and in the vicinity of its submarine outfall located in a Mediterranean coastal zone. Refined predicted environmental concentrations (PECs) were calculated in effluents based on consumption data and human excretion rates. PECs were estimated in the sea using the hydrodynamic MARS 3D model integrating meteorological data, oceanic conditions (wind, tide, atmospheric pressure), freshwater and sewage inputs. Measured environmental concentrations (MECs) were compared to PECs to assess the estimation relevance. In the coastal zone, PEC and MEC were in the same magnitude range. Modeling of Cbz diffusion and advection just above the submarine outfall showed the influence of the thermocline during summer, with low diffusion of Cbz from the bottom to the surface. This work allowed understanding the dispersion of target compounds and deserved further development for a better acknowledgement of vulnerability at local scales.

  17. Reducing PEC uncertainty in coastal zones: a case study on carbamazepine, oxcarbazepine and their metabolites.

    PubMed

    Fenet, Hélène; Arpin-Pont, Lauren; Vanhoutte-Brunier, Alice; Munaron, Dominique; Fiandrino, Annie; Martínez Bueno, Maria-Jesus; Boillot, Clotilde; Casellas, Claude; Mathieu, Olivier; Gomez, Elena

    2014-07-01

    Concentrations of the antiepileptic drugs carbamazepine (Cbz), oxcarbazepine (OxCz) and their main metabolites were predicted in a wastewater treatment plant (WTP) and in the vicinity of its submarine outfall located in a Mediterranean coastal zone. Refined predicted environmental concentrations (PECs) were calculated in effluents based on consumption data and human excretion rates. PECs were estimated in the sea using the hydrodynamic MARS 3D model integrating meteorological data, oceanic conditions (wind, tide, atmospheric pressure), freshwater and sewage inputs. Measured environmental concentrations (MECs) were compared to PECs to assess the estimation relevance. In the coastal zone, PEC and MEC were in the same magnitude range. Modeling of Cbz diffusion and advection just above the submarine outfall showed the influence of the thermocline during summer, with low diffusion of Cbz from the bottom to the surface. This work allowed understanding the dispersion of target compounds and deserved further development for a better acknowledgement of vulnerability at local scales. PMID:24742703

  18. Use of percutaneous endoscopic colostomy (PEC) to treat sigmoid volvulus: a systematic review

    PubMed Central

    Frank, Lucinda; Moran, Alex; Beaton, Ceri

    2016-01-01

    Background and aim: Percutaneous endoscopic colostomy provides an alternative management option for patients with recurrent sigmoid volvulus who are considered too high risk to undergo surgery. We reviewed the literature to assess whether the National Institute for Health and Clinical Excellence guidelines published in 2006 supporting the use of percutaneous endoscopic colostomy are still valid. Methods: A systematic literature search was conducted using PubMed, Web of Science, and Embase. The exploded search terms “Percutaneous Endoscopic Colostomy” and “Sigmoid Volvulus” were used. Librarian support was used to ensure the maximum number of relevant articles were returned. Identified abstracts were then analyzed and included if they met the inclusion criteria. Results: Five observational studies and 5 case reports were identified that met the inclusion criteria. They provided data on 56 patients with recurrent sigmoid volvulus treated with percutaneous endoscopic colostomy placement. Sixteen of the 56 patients were treated with a single percutaneous endoscopic colostomy (PEC) tube while 38 patients were treated with 2 PEC tubes. For 2 patients the details of the procedure were unknown. Five patients developed major complications following the procedure: 1 patient developed peritonitis after 4 days, due to fecal contamination secondary to tube migration and 2 patients with cognitive impairment pulled their PEC tubes out. Two other patients died following PEC insertion. Nine patients developed minor complications following the procedure. The most commonly reported minor complication was infection at the PEC site. Four of 56 patients developed a recurrent sigmoid volvulus with a PEC tube in situ. Conclusion: Although in these case series there is a 21 % risk of morbidity and 5 % risk of mortality from the use of a PEC, this is favorable compared to the mortality risk of 6.6 % to 44 % reported with operative intervention. This review of contemporary

  19. Trends in ExPEC serogroups in the UK and their significance.

    PubMed

    Ciesielczuk, H; Jenkins, C; Chattaway, M; Doumith, M; Hope, R; Woodford, N; Wareham, D W

    2016-10-01

    Extra-intestinal pathogenic Escherichia coli are a significant cause of urinary tract infection and bacteraemia within the UK. We sought to identify the serogroups of 658 E. coli isolates collected in the UK between January 2011 and March 2012, to better understand the ExPEC population and understand the relevance of serogroups in this pathotype. Isolates were typed and serogroup identified using established phenotypic and molecular methods. Sixty-two serogroups were identified; 54 among urinary isolates and 35 among bloodstream isolates. However, serogroups O25, O6, and O2 dominated both infection types. These serogroups were linked to the major ExPEC STs as follows: ST131-O25, ST73-O6, ST127-O6, and ST95-O2. The serogroup data from this study have increased our understanding of the ExPEC population in the UK, but also highlighted key ST-serogroup relationships within the major ExPEC clones. These data can be used to guide vaccine design and in the development of laboratory diagnostic tests targeting the ExPEC population. PMID:27329302

  20. Chasing the long tail of environmental data: PEcAn is nuts about Brown Dog

    NASA Astrophysics Data System (ADS)

    Dietze, M.; Cowdery, E.; Desai, A. R.; Gardella, A.; Kelly, R.; Kooper, R.; LeBauer, D.; Mantooth, J.; McHenry, K.; Serbin, S.; Shiklomanov, A. N.; Simkins, J.; Viskari, T.; Raiho, A.

    2015-12-01

    The Predictive Ecosystem Analyzer (PEcAn) is a ecological modeling informatics system that manages the flows of information in and out of terrestrial biosphere models, provenance tracking, visualization, analysis, and model-data fusion. We are in the process of scaling the PEcAn system from one that currently supports a handful of models and system nodes to one that aims to provide bottom-up connectivity across much of the model-data integration done by the terrestrial biogeochemistry community. This talk reports on the current state of PEcAn, it's data processing workflows, and the near- and long-term challenges faced. Particular emphasis will be given to the tools being developed by the Brown Dog project to make unstructured, un-curated data more accessible: the Data Access Proxy (DAP) and the Data Tilling Service (DTS). The use of the DAP to process meteorological data and the DTS to read vegetation data will be demonstrated and other Brown Dog environmental case studies will be briefly touched on. Beyond data processing, facilitating data discovery and import into PEcAn and distributing analyses across the PEcAn network (i.e. bringing models to data) are key challenges moving forward.

  1. Six International Conferences of PEC (The Peace Education Commission). Peace Education Miniprints No. 87.

    ERIC Educational Resources Information Center

    Bjerstedt, Ake

    This pamphlet offers an overview of five larger reports in order to facilitate the process of locating contributions originating from five peace conferences between 1990-1994. The Peace Education Commission (PEC) arranged five conferences in Groningen (The Netherlands), Firenze (Italy), Kyoto (Japan), Budapest (Hungary) and Valletta (Malta). A…

  2. The Application of PECS in a Deaf Child with Autism: A Case Study

    ERIC Educational Resources Information Center

    Malandraki, Georgia A.; Okalidou, Areti

    2007-01-01

    A 10-year-old nonverbal Greek boy, C.Z., who had been diagnosed with both bilateral sensorineural profound hearing loss and autism, was taught to use the Picture Exchange Communication System (PECS), with some modifications and extensions, over a 4-month intensive intervention period. C.Z.'s original communication and behavioral status as well as…

  3. Effects of PECS Phase III Application Training on Independent Mands in Young Children with Autism

    ERIC Educational Resources Information Center

    Love, Jessica June

    2013-01-01

    The purpose of this study was to examine the effects of PECS phase III application training on independent mands in young children with autism. Participants were five children with autism ranging from ages 2 to 4 years old. A multiple baseline across participants was used to evaluate acquisition of independent correct mands across baseline and…

  4. Comparison of PECS and the Use of a VOCA: A Replication

    ERIC Educational Resources Information Center

    Beck, Ann R.; Stoner, Julia B.; Bock, Stacey J.; Parton, Tom

    2008-01-01

    This study compares use of the Picture Exchange Communication System (PECS) and a Voice Output Communication Aide (VOCA) with four preschool children who were either non-speaking or limited in their ability to speak and did not use an AAC system to communicate functionally. An alternating treatment single subject design was used to measure…

  5. The PEcAn Project: Model-Data Ecoinformatics for the Observatory Era

    NASA Astrophysics Data System (ADS)

    Dietze, M. C.; LeBauer, D. S.; Davidson, C. D.; Desai, A. R.; Kooper, R.; McHenry, K.; Mulrooney, P.

    2011-12-01

    The fundamental questions about how terrestrial ecosystems will respond to climate change are straightforward and well known, yet a small number of important gaps separate the information we have gathered from the understanding required to inform policy and management. A critical gap is that no one data source provides a complete picture of the terrestrial biosphere, and therefore multiple data sources must be integrated in a sensible manner. Process-based models represent an ideal framework for this synthesis, but to date model-data synthesize has only made use of a subset of the available data types, and remains inaccessible to much of the scientific community, largely due to the daunting ecoinformatics challenges. The Predictive Ecosystem Analyzer (PEcAn) is an open-source scientific workflow system and ecoinformatics toolbox that manages the flow of information in and out of regional-scale terrestrial biosphere models, facilitates formal data assimilation, and enables more effective feedbacks between models and field research. PEcAn makes complex analyses transparent, repeatable, and accessible to a diverse array of researchers. PEcAn is not model specific, but rather encapsulates any ecosystem model within a set of standardized input and output modules. Herein we demonstrate PEcAn's ability to automate many of the tasks involved in modeling by gathering and processing a diverse arrays of data sets, initiating ensembles of model runs, visualizing output, and comparing models to observations. PEcAn employs a fully Bayesian approach to model parameterization and the estimation of ecosystem pools and fluxes that allows a straightforward propagation of uncertainties into analyses and forecasts. This approach also makes possible the synthesis of a diverse array of data types operating at different spatial and temporal scales and to easily update predictions as new information becomes available. We also demonstrate PEcAn's ability to iteratively synthesize

  6. The effects of PECS teaching to Phase III on the communicative interactions between children with autism and their teachers.

    PubMed

    Carr, Deborah; Felce, Janet

    2007-04-01

    The study investigated the impact of mastery of the Picture Exchange Communication System (PECS) to Phase III, on the communications of children with autism. Children aged between 3 and 7 years, formed a PECS intervention group and a non-intervention control group. The intervention group received 15 h of PECS teaching over 5 weeks. Three 2-h classroom observations recorded communications between the children and their teachers. These occurred: 6 weeks before teaching; during the week immediately prior to teaching; during the week immediately following teaching. For the control group, two 2-h observations were separated by a 5-week interval without PECS teaching. Communicative initiations and dyadic interactions increased significantly between the children and teachers in the PECS group but not for the control group.

  7. The ABCG transporter PEC1/ABCG32 is required for the formation of the developing leaf cuticle in Arabidopsis.

    PubMed

    Fabre, Guillaume; Garroum, Imène; Mazurek, Sylwester; Daraspe, Jean; Mucciolo, Antonio; Sankar, Martial; Humbel, Bruno M; Nawrath, Christiane

    2016-01-01

    The cuticle is an essential diffusion barrier on aerial surfaces of land plants whose structural component is the polyester cutin. The PERMEABLE CUTICLE1/ABCG32 (PEC1) transporter is involved in plant cuticle formation in Arabidopsis. The gpat6 pec1 and gpat4 gapt8 pec1 double and triple mutants are characterized. Their PEC1-specific contributions to aliphatic cutin composition and cuticle formation during plant development are revealed by gas chromatography/mass spectrometry and Fourier-transform infrared spectroscopy. The composition of cutin changes during rosette leaf expansion in Arabidopsis. C16:0 monomers are in higher abundance in expanding than in fully expanded leaves. The atypical cutin monomer C18:2 dicarboxylic acid is more prominent in fully expanded leaves. Findings point to differences in the regulation of several pathways of cutin precursor synthesis. PEC1 plays an essential role during expansion of the rosette leaf cuticle. The reduction of C16 monomers in the pec1 mutant during leaf expansion is unlikely to cause permeability of the leaf cuticle because the gpat6 mutant with even fewer C16:0 monomers forms a functional rosette leaf cuticle at all stages of development. PEC1/ABCG32 transport activity affects cutin composition and cuticle structure in a specific and non-redundant fashion.

  8. Genetic Characterization of ExPEC-Like Virulence Plasmids among a Subset of NMEC.

    PubMed

    Nicholson, Bryon A; West, Aaron C; Mangiamele, Paul; Barbieri, Nicolle; Wannemuehler, Yvonne; Nolan, Lisa K; Logue, Catherine M; Li, Ganwu

    2016-01-01

    Neonatal Meningitis Escherichia coli (NMEC) is one of the most common causes of neonatal bacterial meningitis in the US and elsewhere resulting in mortality or neurologic deficits in survivors. Large plasmids have been shown experimentally to increase the virulence of NMEC in the rat model of neonatal meningitis. Here, 9 ExPEC-like plasmids were isolated from NMEC and sequenced to identify the core and accessory plasmid genes of ExPEC-like virulence plasmids in NMEC and create an expanded plasmid phylogeny. Results showed sequenced virulence plasmids carry a strongly conserved core of genes with predicted functions in five distinct categories including: virulence, metabolism, plasmid stability, mobile elements, and unknown genes. The major functions of virulence-associated and plasmid core genes serve to increase in vivo fitness by adding multiple iron uptake systems to the genetic repertoire to facilitate NMEC's survival in the host's low iron environment, and systems to enhance bacterial resistance to host innate immunity. Phylogenetic analysis based on these core plasmid genes showed that at least two lineages of ExPEC-like plasmids could be discerned. Further, virulence plasmids from Avian Pathogenic E. coli and NMEC plasmids could not be differentiated based solely on the genes of the core plasmid genome.

  9. dbPEC: a comprehensive literature-based database for preeclampsia related genes and phenotypes

    PubMed Central

    Uzun, Alper; Triche, Elizabeth W.; Schuster, Jessica; Dewan, Andrew T.; Padbury, James F.

    2016-01-01

    Preeclampsia is one of the most common causes of fetal and maternal morbidity and mortality in the world. We built a Database for Preeclampsia (dbPEC) consisting of the clinical features, concurrent conditions, published literature and genes associated with Preeclampsia. We included gene sets associated with severity, concurrent conditions, tissue sources and networks. The published scientific literature is the primary repository for all information documenting human disease. We used semantic data mining to retrieve and extract the articles pertaining to preeclampsia-associated genes and performed manual curation. We deposited the articles, genes, preeclampsia phenotypes and other supporting information into the dbPEC. It is publicly available and freely accessible. Previously, we developed a database for preterm birth (dbPTB) using a similar approach. Using the gene sets in dbPTB, we were able to successfully analyze a genome-wide study of preterm birth including 4000 women and children. We identified important genes and pathways associated with preterm birth that were not otherwise demonstrable using genome-wide approaches. dbPEC serves not only as a resources for genes and articles associated with preeclampsia, it is a robust source of gene sets to analyze a wide range of high-throughput data for gene set enrichment analysis. Database URL: http://ptbdb.cs.brown.edu/dbpec/ PMID:26946289

  10. The PecT repressor coregulates synthesis of exopolysaccharides and virulence factors in Erwinia chrysanthemi.

    PubMed

    Condemine, G; Castillo, A; Passeri, F; Enard, C

    1999-01-01

    Erwinia chrysanthemi 3937 synthesizes an exopolysaccharide (EPS) composed of rhamnose, galactose, and galacturonic acid. Fourteen transcriptional fusions in genes required for EPS synthesis, named eps, were obtained by Tn5-B21 mutagenesis. Eleven of them are clustered on the chromosome and are repressed by PecT, a regulator of pectate lyase synthesis. In addition, expression of these fusions is repressed by the catabolite regulatory protein, CRP, and induced in low osmolarity medium. The three other mutations are located in genes that are not regulated by pecT. A 13-kb DNA fragment containing pecT-regulated eps genes has been cloned. All the genes identified on this fragment are transcribed in the same orientation and could form a large operon. The promoter region of this operon has been sequenced. It contains a JUMP-start sequence, a sequence required for the expression of polysaccharide-associated operons. E. chrysanthemi 3937 produces a systemic soft rot on its host Saintpaulia ionantha. An eps mutant was less efficient than the wild-type strain in initiating a maceration symptom, suggesting that production of EPS is required for the full expression of the E. chrysanthemi virulence. PMID:9885192

  11. dbPEC: a comprehensive literature-based database for preeclampsia related genes and phenotypes.

    PubMed

    Uzun, Alper; Triche, Elizabeth W; Schuster, Jessica; Dewan, Andrew T; Padbury, James F

    2016-01-01

    Preeclampsia is one of the most common causes of fetal and maternal morbidity and mortality in the world. We built a Database for Preeclampsia (dbPEC) consisting of the clinical features, concurrent conditions, published literature and genes associated with Preeclampsia. We included gene sets associated with severity, concurrent conditions, tissue sources and networks. The published scientific literature is the primary repository for all information documenting human disease. We used semantic data mining to retrieve and extract the articles pertaining to preeclampsia-associated genes and performed manual curation. We deposited the articles, genes, preeclampsia phenotypes and other supporting information into the dbPEC. It is publicly available and freely accessible. Previously, we developed a database for preterm birth (dbPTB) using a similar approach. Using the gene sets in dbPTB, we were able to successfully analyze a genome-wide study of preterm birth including 4000 women and children. We identified important genes and pathways associated with preterm birth that were not otherwise demonstrable using genome-wide approaches. dbPEC serves not only as a resources for genes and articles associated with preeclampsia, it is a robust source of gene sets to analyze a wide range of high-throughput data for gene set enrichment analysis. Database URL: http://ptbdb.cs.brown.edu/dbpec/. PMID:26946289

  12. UPDATE ON PEC ACTIVITIES INCLUDING NEW EVALUATION CRITERIA, THE APPLICATION COMPLETENESS CHECKLIST, AND STATUS OF THE WEBSITE DEVELOPMENT

    EPA Science Inventory

    US EPA's Pathogen Equivalency Committee (PEC) has updated the evaluation criteria it uses to make recommendations of equivalency (to processes acceptable under 40CFR503) on innovative or alternative sludge pathogen reduction processes. These criteria will be presented along with ...

  13. The PEcAn Project: Accessible Tools for On-demand Ecosystem Modeling

    NASA Astrophysics Data System (ADS)

    Cowdery, E.; Kooper, R.; LeBauer, D.; Desai, A. R.; Mantooth, J.; Dietze, M.

    2014-12-01

    Ecosystem models play a critical role in understanding the terrestrial biosphere and forecasting changes in the carbon cycle, however current forecasts have considerable uncertainty. The amount of data being collected and produced is increasing on daily basis as we enter the "big data" era, but only a fraction of this data is being used to constrain models. Until we can improve the problems of model accessibility and model-data communication, none of these resources can be used to their full potential. The Predictive Ecosystem Analyzer (PEcAn) is an ecoinformatics toolbox and a set of workflows that wrap around an ecosystem model and manage the flow of information in and out of regional-scale TBMs. Here we present new modules developed in PEcAn to manage the processing of meteorological data, one of the primary driver dependencies for ecosystem models. The module downloads, reads, extracts, and converts meteorological observations to Unidata Climate Forecast (CF) NetCDF community standard, a convention used for most climate forecast and weather models. The module also automates the conversion from NetCDF to model specific formats, including basic merging, gap-filling, and downscaling procedures. PEcAn currently supports tower-based micrometeorological observations at Ameriflux and FluxNET sites, site-level CSV-formatted data, and regional and global reanalysis products such as the North American Regional Reanalysis and CRU-NCEP. The workflow is easily extensible to additional products and processing algorithms.These meteorological workflows have been coupled with the PEcAn web interface and now allow anyone to run multiple ecosystem models for any location on the Earth by simply clicking on an intuitive Google-map based interface. This will allow users to more readily compare models to observations at those sites, leading to better calibration and validation. Current work is extending these workflows to also process field, remotely-sensed, and historical

  14. Probability Density Function for Waves Propagating in a Straight PEC Rough Wall Tunnel

    SciTech Connect

    Pao, H

    2004-11-08

    The probability density function for wave propagating in a straight perfect electrical conductor (PEC) rough wall tunnel is deduced from the mathematical models of the random electromagnetic fields. The field propagating in caves or tunnels is a complex-valued Gaussian random processing by the Central Limit Theorem. The probability density function for single modal field amplitude in such structure is Ricean. Since both expected value and standard deviation of this field depend only on radial position, the probability density function, which gives what is the power distribution, is a radially dependent function. The radio channel places fundamental limitations on the performance of wireless communication systems in tunnels and caves. The transmission path between the transmitter and receiver can vary from a simple direct line of sight to one that is severely obstructed by rough walls and corners. Unlike wired channels that are stationary and predictable, radio channels can be extremely random and difficult to analyze. In fact, modeling the radio channel has historically been one of the more challenging parts of any radio system design; this is often done using statistical methods. In this contribution, we present the most important statistic property, the field probability density function, of wave propagating in a straight PEC rough wall tunnel. This work only studies the simplest case--PEC boundary which is not the real world but the methods and conclusions developed herein are applicable to real world problems which the boundary is dielectric. The mechanisms behind electromagnetic wave propagation in caves or tunnels are diverse, but can generally be attributed to reflection, diffraction, and scattering. Because of the multiple reflections from rough walls, the electromagnetic waves travel along different paths of varying lengths. The interactions between these waves cause multipath fading at any location, and the strengths of the waves decrease as the distance

  15. A feasibility study of accelerated polychemotherapy with cisplatin, epidoxorubicin and cyclophosphamide (PEC) in advanced ovarian cancer.

    PubMed Central

    Pronzato, P.; Bertelli, G.; Vigani, A.; Vaira, F.

    1996-01-01

    We have evaluated the feasibility of an increase in dose intensity of the cisplatin, epidoxorubicin and cyclophosphamide (PEC) regimen, with granulocyte colony-stimulating factor (G-CSF) support, in 22 patients with advanced ovarian cancer. Twenty-one patients (95.4%) received six cycles of treatment: of these, 13 (61.9%) were also able to repeat cycles every 14 days as planned. Marrow toxicity was similar to that observed during conventional treatments. No severe mucositis or thrombocytopenia was observed. A clinical complete response was observed in 9 out of 16 evaluable patients (56.2%). PMID:8645591

  16. Passive emission colorimetric sensor (PECS) for measuring emission rates of formaldehyde based on an enzymatic reaction and reflectance photometry.

    PubMed

    Shinohara, Naohide; Kajiwara, Tomohisa; Ohnishi, Masato; Kodama, Kenichi; Yanagisawa, Yukio

    2008-06-15

    A coin-sized passive emission colorimetric sensor (PECS) based on an enzymatic reaction and a portable reflectance photometry device were developed to determine the emission rates of formaldehyde from building materials and other materials found indoors in only 30 minutes on-site. The color change of the PECS linearly correlated to the concentration of formaldehyde aqueous solutions up to 28 microg/mL. The correlation between the emission rates measured by using the PECS and those measured by using a desiccator method or by using a chamber method was fitted with a linear function and a power function, and the determination coefficients were more than 0.98. The reproducible results indicate that the emission rates could be obtained with the correlation equations from the data measured by using the PECS and the portable reflectance photometry device. Limits of detection (LODs) were 0.051 mg/L for the desiccator method and 3.1 microg/m2/h for the chamber method. Thus, it was confirmed that the emission rates of formaldehyde from the building materials classified as F four-star (< 0.3 mg/L (desiccator method) or < 5.0 microg/m2/h (chamber method)), based on Japanese Industrial Standards (JIS), could be measured with the PECS. The measurement with PECS was confirmed to be precise (RSD < 10%). Other chemicals emitted from indoor materials, such as methanol, ethanol, acetone, toluene, and xylene, interfered little with the measurement of formaldehyde emission rates by using the PECS.

  17. TolC Promotes ExPEC Biofilm Formation and Curli Production in Response to Medium Osmolarity

    PubMed Central

    Hou, Bo; Meng, Xian-Rong; Zhang, Li-Yuan; Tan, Chen; Jin, Hui; Zhou, Rui; Gao, Jian-Feng; Wu, Bin; Li, Zi-Li; Chen, Huan-Chun; Bi, Ding-Ren; Li, Shao-Wen

    2014-01-01

    While a high osmolarity medium activates Cpx signaling and causes CpxR to repress csgD expression, and efflux protein TolC protein plays an important role in biofilm formation in Escherichia coli, whether TolC also responds to an osmolarity change to regulate biofilm formation in extraintestinal pathogenic E. coli (ExPEC) remains unknown. In this study, we constructed ΔtolC mutant and complement ExPEC strains to investigate the role of TolC in the retention of biofilm formation and curli production capability under different osmotic conditions. The ΔtolC mutant showed significantly decreased biofilm formation and lost the ability to produce curli fimbriae compared to its parent ExPEC strain PPECC42 when cultured in M9 medium or 1/2 M9 medium of increased osmolarity with NaCl or sucrose at 28°C. However, biofilm formation and curli production levels were restored to wild-type levels in the ΔtolC mutant in 1/2 M9 medium. We propose for the first time that TolC protein is able to form biofilm even under high osmotic stress. Our findings reveal an interplay between the role of TolC in ExPEC biofilm formation and the osmolarity of the surrounding environment, thus providing guidance for the development of a treatment for ExPEC biofilm formation. PMID:25243151

  18. Minute perivascular epithelioid cell (PEC) nests in the abdominal lymph nodes--a putative precursor of PEComa.

    PubMed

    Nagasaka, Toru; Murakami, Yoshiko; Sasaki, Eiichi; Hosoda, Waki; Nakanishi, Toru; Yatabe, Yasushi

    2015-04-01

    A perivascular epithelioid cell tumor (PEComa) is a peculiar growth defined as a mesenchymal tumor composed of histologically and immunohistochemically distinct perivascular epithelioid cells (PECs). Because neither normal counterparts nor precursor lesions of PEComa have been identified, we examined minute PEC nests, ranged from 0.8 mm to 10 mm, to investigate the possible origin of the PEComa. We examined a total of 80 677 para-aortic and pelvic lymph nodes that were systematically dissected from 1656 patients for gynecological malignancies. The identified lesions were confirmed immunohistochemically with multiple PEC markers, including smooth muscle actin, HMB45, melan-A, MiTF, ER and PgR. A total of 66 minute PEC nests were found in 21 patients (1.3% of the total population) with an average frequency of 3.1 lesions per patient. In cases of multiple involvement, 11 of 13 nests were located at the same level of multiple lymph node or on continuous levels. The lesions were preferentially distributed at the level of para-aortic and high pelvic lymph nodes. All nests were positive for actin and HMB45, whereas the other markers were positive with varying frequencies. The minute PEC nests may be associated with the possible normal counterpart of PEComas.

  19. In vivo correlates of molecularly inferred virulence among extraintestinal pathogenic Escherichia coli (ExPEC) in the wax moth Galleria mellonella model system

    PubMed Central

    Williamson, Deborah A; Mills, Grant; Johnson, James R; Porter, Stephen; Wiles, Siouxsie

    2014-01-01

    In contrast to commensal Escherichia coli, extraintestinal pathogenic E. coli (ExPEC) strains possess an array of virulence-associated genes. We sought to establish the feasibility of using the invertebrate Galleria mellonella (greater wax moth) for assessing ExPEC virulence and to investigate the correlation between genotypic determinants of virulence and in vivo pathogenicity. We observed a correlation between the number of virulence genes and larval survival, such that ExPEC isolates with higher virulence scores killed larvae significantly faster than isolates with lower virulence scores. By correlating genotypic and phenotypic virulence, we provide preliminary validation of this model for future studies investigating ExPEC virulence. PMID:24518442

  20. A Comparison of PECS and iPad to Teach Requesting to Pre-schoolers with Autistic Spectrum Disorders.

    PubMed

    Agius, May M; Vance, Margaret

    2016-01-01

    Few studies have compared the efficacy of the Picture Exchange Communication System (PECS) and iPads used as speech generating devices (SGDs), and none have targeted preschoolers. This study compares the relative efficacy of PECS and an iPad/SGD with three preschool-aged children with autism spectrum disorder and limited functional speech who lived in Malta. The study utilized an adapted alternating treatment design embedded in a multiple baseline design, with requesting of reinforcers as the dependent variable. Visual analysis of the results indicated that all participants required more prompted trials and sessions for the iPad/SGD condition. All participants learned a three step navigational sequence on the iPad. Participant preference probes were inconclusive and were not linked to speed of acquisition of requesting skills. Results suggest that both PECS and an iPad could be appropriate for teaching requesting skills to beginning communicators.

  1. Thermoelectric Properties of Hot-Pressed and PECS-Sintered Magnesium-Doped Copper Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Morelli, Donald T.

    2011-05-01

    Copper aluminum oxide (CuAlO2) is considered as a potential candidate for thermoelectric applications. Partially magnesium-doped CuAlO2 bulk pellets were fabricated using solid-state reactions, hot-pressing, and pulsed electric current sintering (PECS) techniques. X-ray diffraction and scanning electron microscopy were adopted for structural analysis. High-temperature transport property measurements were performed on hot-pressed samples. Electrical conductivity increased with Mg doping before secondary phases became significant, while the Seebeck coefficient displayed the opposite trend. Thermal conductivity was consistently reduced as the Mg concentration increased. Effects of Mg doping, preparation conditions, and future modification on this material's properties are discussed.

  2. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current-voltage (I-V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I-V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research.

  3. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance.

    PubMed

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current-voltage (I-V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I-V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research. PMID:27455067

  4. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current–voltage (I–V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I–V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research.

  5. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance.

    PubMed

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current-voltage (I-V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I-V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research.

  6. Effectiveness of the Picture Exchange Communication System (PECS) on Communication and Speech for Children with Autism Spectrum Disorders: A Meta-Analysis

    ERIC Educational Resources Information Center

    Flippin, Michelle; Reszka, Stephanie; Watson, Linda R.

    2010-01-01

    Purpose: The Picture Exchange Communication System (PECS) is a popular communication-training program for young children with autism spectrum disorders (ASD). This meta-analysis reviews the current empirical evidence for PECS in affecting communication and speech outcomes for children with ASD. Method: A systematic review of the literature on PECS…

  7. Meta-Analysis of PECS with Individuals with ASD: Investigation of Targeted versus Non-Targeted Outcomes, Participant Characteristics, and Implementation Phase

    ERIC Educational Resources Information Center

    Ganz, Jennifer B.; Davis, John L.; Lund, Emily M.; Goodwyn, Fara D.; Simpson, Richard L.

    2012-01-01

    The Picture Exchange Communication System (PECS) is a widely used picture/icon aided augmentative communication system designed for learners with autism and other developmental disorders. This meta-analysis analyzes the extant empirical literature for PECS relative to targeted (functional communication) and non-targeted concomitant outcomes…

  8. Effects of Mother-Implemented Picture Exchange Communication System (PECS) Training on Independent Communicative Behaviors of Young Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Park, Ju Hee; Alber-Morgan, Sheila R.; Cannella-Malone, Helen

    2011-01-01

    This study examined the effects of mother-implemented Picture Exchange Communication System (PECS) training on the independent communication of three young children with autism spectrum disorders. Three mothers were trained to teach their child PECS Phases 1 through 3B, which they did with high integrity. Moreover, all three children successfully…

  9. Long-Term Effects of PECS on Social-Communicative Skills of Children with Autism Spectrum Disorders: A Follow-Up Study

    ERIC Educational Resources Information Center

    Lerna, Anna; Esposito, Dalila; Conson, Massimiliano; Massagli, Angelo

    2014-01-01

    Background: The Picture Exchange Communication System (PECS) is a popular augmentative communication system frequently used with "nonverbal" children with autism. Several studies suggested that PECS could represent an effective tool for promoting improvement of several social-communicative skills. Only sparse evidence is instead…

  10. Partitionable-space enhanced coagulation (PEC) reactor and its working mechanism: a new prospective chemical technology for phosphorus pollution control.

    PubMed

    Zhang, Meng; Zheng, Ping; Abbas, Ghulam; Chen, Xiaoguang

    2014-02-01

    Phosphorus pollution control and phosphorus recycling, simultaneously, are focus of attention in the wastewater treatment. In this work, a novel reactor named partitionable-space enhanced coagulation (PEC) was invented for phosphorus control. The working performance and process mechanism of PEC reactor were investigated. The results showed that the PEC technology was highly efficient and cost-effective. The volumetric removal rate (VRR) reached up to 2.86 ± 0.04 kg P/(m(3) d) with a phosphorus removal rate of over 97%. The precipitant consumption was reduced to 2.60-2.76 kg Fe(II)/kg P with low operational cost of $ 0.632-0.673/kg P. The peak phosphorus content in precipitate was up to 30.44% by P2O5, which reveal the benefit of the recycling phosphorus resource. The excellent performance of PEC technology was mainly attributed to the partitionable-space and 'flocculation filter'. The partition limited the trans-regional back-mixing of reagents along the reactor, which promoted the precipitation reaction. The 'flocculation filter' retained the microflocs, enhancing the flocculation process.

  11. PECS and VOCAs to Enable Students with Developmental Disabilities to Make Requests: An Overview of the Literature

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; O'Reilly, Mark F.; Cuvo, Anthony J.; Singh, Nirbhay N.; Sigafoos, Jeff; Didden, Robert

    2007-01-01

    This paper provides an overview of the literature dealing with the use of the Picture Exchange Communication System (PECS) and voice output communication aids (VOCAs) for promoting the performance of requests by students with developmental disabilities. Computerized and manual searches were carried out to identify the studies published during the…

  12. Comparative Efficacy of the Picture Exchange Communication System (PECS) versus a Speech-Generating Device: Effects on Requesting Skills

    ERIC Educational Resources Information Center

    Boesch, Miriam C.; Wendt, Oliver; Subramanian, Anu; Hsu, Ning

    2013-01-01

    An experimental, single-subject research study investigated the comparative efficacy of the Picture Exchange Communication System (PECS) versus a speech-generating device (SGD) in developing requesting skills for three elementary-age children with severe autism and little to no functional speech. Results demonstrated increases in requesting…

  13. Effects of Implementing the Picture Exchange Communication System (PECS) with Adults with Developmental Disabilities and Severe Communication Deficits

    ERIC Educational Resources Information Center

    Conklin, Carl G.; Mayer, G. Roy

    2011-01-01

    The purpose of this study is to evaluate the effects of "Picture Exchange Communication System" (PECS) training, using a multiple baseline design on the independent initiations of three adults with developmental disabilities and severe communication deficits. All participants increased their independent initiations, although at different levels of…

  14. "Brief Report: Increase in Production of Spoken Words in Some Children with Autism after PECS Teaching to Phase III"

    ERIC Educational Resources Information Center

    Carr, Deborah; Felce, Janet

    2007-01-01

    The context for this work was an evaluation study [Carr, D., & Felce, J. A. (in press)] of the early phases of the Picture Exchange Communication System (PECS) [Frost, L. A., & Bondy, A. S. (1994). "The picture exchange communication system training manual." Cherry Hill, NJ: Pyramid Educational Consultants, Inc.; Frost, L. A., & Bondy, A. S.…

  15. PecSys: in situ gelling system for optimised nasal drug delivery.

    PubMed

    Watts, Peter; Smith, Alan

    2009-05-01

    PecSys (PS) is a proprietary pectin-based drug delivery system designed to gel when applied to mucosal surfaces and with potential areas of application for drugs used in local and systemic disease therapy. The current area of focus is intranasal drug delivery where PS is being used to optimise absorption of lipophilic drugs into the systemic circulation. Pectin is described as GRAS (generally regarded as safe) with an excellent regulatory position through its long history of pharmaceutical and food usage. Tests to measure the functional gelling properties of pectin raw material and PS have been devised and validated. The PS-based products at the most advanced stages of development are intranasal formulations containing opioid analgesics intended to provide rapid pain relief with simple and convenient dosing and minimal side effects. The profile of such drugs may not be optimal through current routes of delivery and the ability of PS to modulate their pharmacokinetic profiles, such as attenuation of the peak plasma concentration (Cmax), has been demonstrated in clinical testing. The lead product using PS is a fentanyl nasal spray formulation (NasalFent), which has successfully met the primary objective in a pivotal Phase III clinical study and is scheduled for regulatory filings in the first half of 2009.

  16. IUE observations of circumstellar emission from the late-type variable R AQR (M6 + pec)

    NASA Technical Reports Server (NTRS)

    Hobbs, R. W.; Michalitsianos, A. G.; Kafatos, M.

    1981-01-01

    The IUE observations of R Aqr (M7 + pec) obtained in low dispersion are discussed with particular reference to circumstellar emission. Strong permitted, semiforbidden, and forbidden emission lines are seen, superimposed on a bright ultraviolet continuum. It is deduced that the strong emission line spectrum that involves C III, C IV, Si III, (0 II) and (0 III) probably arises from a dense compact nebula the size of which is comparable to the orbital radius of the binary system of which R Aqr is the primary star. The low excitation emission lines of Fe II, Mg II, 0 I, and Si II probably a white dwarf, comparable to or somewhat brighter than the Sun, since such a star can produce enough ionizing photons to excite the continuum and emission line spectrum and yet be sufficiently faint as to escape detection by direct observation. The UV continuum is attributed to Balmer recombination from the dense nebula and not to blackbody emission from the hot companion.

  17. RETRACTION: Surface impedance determination of an object located over a planar PEC surface and its use in shape reconstruction Surface impedance determination of an object located over a planar PEC surface and its use in shape reconstruction

    NASA Astrophysics Data System (ADS)

    Seda Ünal, Gül; Yapar, Ali; Akduman, Ibrahim

    2009-06-01

    This paper has substantial overlap with the paper 'Reconstruction of surface impedance of an object located over a planar PEC surface' by Gül Seda Ünal, Mehmet Çayören and Evrim Tetik (2008 Journal of Physics: Conference Series 135 012099). Therefore this article has been retracted by IOP Publishing and by the authors, Gül Seda Ünal, Ali Yapar and Ibrahim Akduman.

  18. [Machinery and mechanical eroticism. A study on the phenomenology of schizophrenia in two painters' artworks in the Reuter Collection (Pecs)].

    PubMed

    Simon, Mária

    2010-01-01

    In this essay, I introduce two schizophrenic artists from the Reuter's Psychopathological Art Collection (Pecs, Hungary), who had been treated in the 1920es.One artist drew a number of sketches of machines; the other created a serial of mechanically erotic pictures. Pictures are analyzed from an intersubjective-phenomenological perspective. Schizophrenic patients' subjective experiences i.e. the experience of reification as well as the intrusivity and uncontrollability of sexuality are particularly emphasized.

  19. Stable hydrogen generation from Ni- and Co-based co-catalysts in supported CdS PEC cell.

    PubMed

    Pareek, Alka; Paik, Pradip; Borse, Pramod H

    2016-07-01

    To improve the limited efficiency and stability of CdS photoanodes in a photoelectrochemical (PEC) cell, the nanostructured CdS photoanode was modified with Ni(OH)2, NiO, Co(OH)2, and Co3O4 water-oxidation-nano co-catalysts (WOC). Co(OH)2 nanorice and Ni(OH)2 nanosheet co-catalysts were obtained by a simple chemical precipitation method. Modification by the co-catalysts gives longer stability (>8 h) to CdS electrodes, and facilitates impulsive H2 evolution in PEC cells. Nano-NiO modification yields a two-fold increase in photocurrent density and the highest H2 evolution of 2.5 mmol h(-1). A dual role for Ni related co-catalysts over CdS surface, that is forming a p-n junction and acting as an effective co-catalyst, improves the photocurrent and hydrogen evolution rate, respectively. Improvement in stability was measured using X-ray photoelectron spectroscopy and prolong chronoamperometry measurements. The present report focuses on exploration of chemically synthesized earth-abundant and cost-effective co-catalysts for PEC H2 generation. PMID:27327992

  20. Stable hydrogen generation from Ni- and Co-based co-catalysts in supported CdS PEC cell.

    PubMed

    Pareek, Alka; Paik, Pradip; Borse, Pramod H

    2016-07-01

    To improve the limited efficiency and stability of CdS photoanodes in a photoelectrochemical (PEC) cell, the nanostructured CdS photoanode was modified with Ni(OH)2, NiO, Co(OH)2, and Co3O4 water-oxidation-nano co-catalysts (WOC). Co(OH)2 nanorice and Ni(OH)2 nanosheet co-catalysts were obtained by a simple chemical precipitation method. Modification by the co-catalysts gives longer stability (>8 h) to CdS electrodes, and facilitates impulsive H2 evolution in PEC cells. Nano-NiO modification yields a two-fold increase in photocurrent density and the highest H2 evolution of 2.5 mmol h(-1). A dual role for Ni related co-catalysts over CdS surface, that is forming a p-n junction and acting as an effective co-catalyst, improves the photocurrent and hydrogen evolution rate, respectively. Improvement in stability was measured using X-ray photoelectron spectroscopy and prolong chronoamperometry measurements. The present report focuses on exploration of chemically synthesized earth-abundant and cost-effective co-catalysts for PEC H2 generation.

  1. Fast Numerical Algorithms for 3-D Scattering from PEC and Dielectric Random Rough Surfaces in Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Lisha

    We present fast and robust numerical algorithms for 3-D scattering from perfectly electrical conducting (PEC) and dielectric random rough surfaces in microwave remote sensing. The Coifman wavelets or Coiflets are employed to implement Galerkin's procedure in the method of moments (MoM). Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O( N). The orthogonality and Riesz basis of the Coiflets generate well conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. The resulting impedance matrix is further sparsified by the matrix-formed standard fast wavelet transform (SFWT). By properly selecting multiresolution levels of the total transformation matrix, the solution precision can be enhanced while matrix sparsity and memory consumption have not been noticeably sacrificed. The unified fast scattering algorithm for dielectric random rough surfaces can asymptotically reduce to the PEC case when the loss tangent grows extremely large. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems. Compared with previous publications and laboratory measurements, good agreement is observed.

  2. Cathepsin K expression in the spectrum of perivascular epithelioid cell (PEC) lesions of the kidney.

    PubMed

    Martignoni, Guido; Bonetti, Franco; Chilosi, Marco; Brunelli, Matteo; Segala, Diego; Amin, Mahul B; Argani, Pedram; Eble, John N; Gobbo, Stefano; Pea, Maurizio

    2012-01-01

    The perivascular epithelioid cell (PEC) is a unique cell type coexpressing contractile proteins (mainly α-smooth muscle actin), melanocytic markers, including microphthalmia-associated transcription factor (MITF), and estrogen and progesterone receptors. It is constantly present in a group of tumors called PEComas. Renal PEComas include the common angiomyolipoma as well as less common lesions such as microscopic angiomyolipoma, intraglomerular lesions, angiomyolipoma with epithelial cysts, epithelioid angiomyolipoma, oncocytoma-like angiomyolipoma and lymphangioleiomyomatosis of the renal sinus. It has been demonstrated that most of these lesions are determined by mutations affecting genes of the tuberous sclerosis complex, tuberous sclerosis 1 (TSC1) and tuberous sclerosis 2 (TSC2), with eventual deregulation of the RHEB/MTOR/RPS6KB2 pathway, and it has been observed that some PEComas regressed during sirolimus therapy, an MTOR inhibitor. Recently, overexpression of MITF has been related to the expression of the papain-like cysteine protease cathepsin K in osteoclasts where it has inhibited MTOR. The aim of this study is to evaluate cathepsin K immunohistochemically in the entire spectrum of PEComa lesions in the kidney. The study population consisted of 84 renal PEComa lesions, including 5 composed predominantly of fat (lipoma-like angiomyolipoma), 15 almost exclusively composed of spindle-shaped smooth muscle cells (leiomyoma-like angiomyolipoma) and 31 common angiomyolipomas composed of a mixture of fat, spindle and epithelioid smooth muscle cells, and abnormal thick-walled blood vessels, 15 microscopic angiomyolipomas, 5 intraglomerular lesions, 2 oncocytoma-like angiomyolipomas, 8 epithelioid angiomyolipomas, 2 angiomyolipomas with epithelial cysts and 1 example of lymphangioleiomyomatosis of the renal sinus. In all of the renal PEComas, cathepsin K was found to be constantly and strongly expressed and seems to be a more powerful marker than other commonly

  3. APPLYING TO THE PEC: A CASE HISTORY - A WALK THROUGH THE PROCEDURE FOR APPLYING FOR EQUIVALENCY USING A RECENT CANDIDATE AS A TRUE EXAMPLE.

    EPA Science Inventory

    The USEPA's Pathogen Equivalency Committee (PEC) is entrusted by its Office of Water to critically evaluate innovative and alternative sludge disinfection processes and make recommendations about their Process to Significantly Reduce Pathogens (PSRP) or Process to Further Reduce ...

  4. The salmochelin receptor IroN itself, but not salmochelin-mediated iron uptake promotes biofilm formation in extraintestinal pathogenic Escherichia coli (ExPEC).

    PubMed

    Magistro, Giuseppe; Hoffmann, Christiane; Schubert, Sören

    2015-01-01

    The key to success of extraintestinal pathogenic Escherichia coli (ExPEC) to colonize niches outside the intestinal tract and to establish infection is the coordinated action of numerous virulence and fitness factors. Intense research revealed not only an arsenal of unique virulence determinants with specific action, but also the multi-functionality of single elements. Especially iron uptake systems of ExPEC proved to be of prime importance. Apart from iron acquisition they optimize certain virulence properties. Here we analyzed the contribution of the salmochelin siderophore system to the ability of ExPEC to form biofilms. In the same iron limited environment, ExPEC displayed a distinct transcriptional profile of siderophore systems. During biofilm formation the iroN gene coding for the specific receptors of the siderophore salmochelin was highly upregulated. Almost no induction was observed during planctonic growth. Disruption of iroN resulted in a reduction of almost 50% in biofilm production. Efficient biofilm formation was not affected in a salmochelin synthesis mutant. Thus, the contribution of IroN is independent from the ability to produce salmochelin. Enhanced expression of IroN did not increase significantly the capacity to form biofilms in ExPEC. Interestingly, the additional expression of IroN or even the acquisition of the entire salmochelin system was not able to improve biofilm formation in a poor biofilm producer like a laboratory E. coli K12 strain. However, complementation with only IroN in an ExPEC iroA deletion mutant was able to restore biofilm formation. The contribution of IroN to biofilm formation appears to require a certain background found in ExPEC, but not in E. coli K12. This study identified the contribution of IroN to biofilm formation and highlights the multi-functional role of iron uptake systems in ExPEC.

  5. A novel method developed for estimating mineralization efficiencies and its application in PC and PEC degradations of large molecule biological compounds with unknown chemical formula.

    PubMed

    Li, Guiying; Liu, Xiaolu; An, Taicheng; Wong, Po Keung; Zhao, Huijun

    2016-05-15

    A new method to estimate the photocatalytic (PC) and photoelectrocatalytic (PEC) mineralization efficiencies of large molecule biological compounds with unknown chemical formula in water was firstly developed and experimentally validated. The method employed chemical oxidation under the standard dichromate chemical oxygen demand (COD) conditions to obtain QCOD values of model compounds with unknown chemical formula. The measured QCOD values were used as the reference to replace QCOD values of model compounds for calculation of the mineralization efficiencies (in %) by assuming the obtained QCOD values are the measure of the theoretical charge required for the complete mineralization of organic pollutants. Total organic carbon (TOC) was also employed as a reference to confirm the mineralization capacity of dichromate chemical oxidation. The developed method was applied to determine the degradation extent of model compounds, such as bovine serum albumin (BSA), lecithin and bacterial DNA, by PC and PEC. Incomplete PC mineralization of all large molecule biological compounds was observed, especially for BSA. But the introduction of electrochemical technique into a PC oxidation process could profoundly improve the mineralization efficiencies of model compounds. PEC mineralization efficiencies of bacterial DNA was the highest, while that of lecithin was the lowest. Overall, PEC degradation method was found to be much effective than PC method for all large molecule biological compounds investigated, with PEC/PC mineralization ratios followed an order of BSA > lecithin > DNA.

  6. Role of the LysR-type transcriptional regulator PecT and DNA supercoiling in the thermoregulation of pel genes, the major virulence factors in Dickeya dadantii.

    PubMed

    Hérault, Elodie; Reverchon, Sylvie; Nasser, William

    2014-03-01

    Bacteria are colonizers of various environments and host organisms, and they are often subjected to drastic temperature variations. Dickeya dadantii is a pathogen infecting a wide range of plant species. Soft rot, the visible symptom, is mainly due to the production of pectate lyases (Pels) that destroy plant cell walls. The production of Pels is controlled by a complex regulation system that responds to various stimuli, such as the presence of pectin, growth phase and temperature. Despite numerous regulatory studies, the thermoregulation mechanism of Pel production remains unexplained. Here, we show that PecT, a previously identified repressor, modulates pel gene expression in a temperature-dependent manner, and we demonstrate that PecT binding on pel promoters increases concomitantly with temperature. High temperatures relax the DNA in D. dadantii, and remarkably, artificial relaxation of DNA at low temperatures increases PecT binding to DNA. Deletion of pecT augmented the capacity of D. dadantii to initiate soft-rot symptoms at high temperatures. These results reveal that DNA topology and PecT act in concert to fine-tune D. dadantii virulence in response to temperature. This novel combination between DNA topology and a conventional transcriptional regulator extends our understanding of the thermoregulation mechanisms involved in bacterial virulence. PMID:23869858

  7. Comparative efficacy of the picture exchange communication system (PECS) versus a speech-generating device: effects on social-communicative skills and speech development.

    PubMed

    Boesch, Miriam C; Wendt, Oliver; Subramanian, Anu; Hsu, Ning

    2013-09-01

    The Picture Exchange Communication System (PECS) and a speech-generating device (SGD) were compared in a study with a multiple baseline, alternating treatment design. The effectiveness of these methods in increasing social-communicative behavior and natural speech production were assessed with three elementary school-aged children with severe autism who demonstrated extremely limited functional communication skills. Results for social-communicative behavior were mixed for all participants in both treatment conditions. Relatively little difference was observed between PECS and SGD conditions. Although findings were inconclusive, data patterns suggest that Phase II of the PECS training protocol is conducive to encouraging social-communicative behavior. Data for speech outcomes did not reveal any increases across participants, and no differences between treatment conditions were observed.

  8. Plasmid pEC156, a Naturally Occurring Escherichia coli Genetic Element That Carries Genes of the EcoVIII Restriction-Modification System, Is Mobilizable among Enterobacteria.

    PubMed

    Werbowy, Olesia; Kaczorowski, Tadeusz

    2016-01-01

    Type II restriction-modification systems are ubiquitous in prokaryotes. Some of them are present in naturally occurring plasmids, which may facilitate the spread of these systems in bacterial populations by horizontal gene transfer. However, little is known about the routes of their dissemination. As a model to study this, we have chosen an Escherichia coli natural plasmid pEC156 that carries the EcoVIII restriction modification system. The presence of this system as well as the cis-acting cer site involved in resolution of plasmid multimers determines the stable maintenance of pEC156 not only in Escherichia coli but also in other enterobacteria. We have shown that due to the presence of oriT-type F and oriT-type R64 loci it is possible to mobilize pEC156 by conjugative plasmids (F and R64, respectively). The highest mobilization frequency was observed when pEC156-derivatives were transferred between Escherichia coli strains, Enterobacter cloacae and Citrobacter freundii representing coliform bacteria. We found that a pEC156-derivative with a functional EcoVIII restriction-modification system was mobilized in enterobacteria at a frequency lower than a plasmid lacking this system. In addition, we found that bacteria that possess the EcoVIII restriction-modification system can efficiently release plasmid content to the environment. We have shown that E. coli cells can be naturally transformed with pEC156-derivatives, however, with low efficiency. The transformation protocol employed neither involved chemical agents (e.g. CaCl2) nor temperature shift which could induce plasmid DNA uptake.

  9. Development of in vitro models to demonstrate the ability of PecSys®, an in situ nasal gelling technology, to reduce nasal run-off and drip

    PubMed Central

    2013-01-01

    Many of the increasing number of intranasal products available for either local or systemic action can be considered sub-optimal, most notably where nasal drip or run-off give rise to discomfort/tolerability issues or reduced/variable efficacy. PecSys, an in situ gelling technology, contains low methoxy (LM) pectin which gels due to interaction with calcium ions present in nasal fluid. PecSys is designed to spray readily, only forming a gel on contact with the mucosal surface. The present study employed two in vitro models to confirm that gelling translates into a reduced potential for drip/run-off: (i) Using an inclined TLC plate treated with a simulated nasal electrolyte solution (SNES), mean drip length [±SD, n = 10] was consistently much shorter for PecSys (1.5 ± 0.4 cm) than non-gelling control (5.8 ± 1.6 cm); (ii) When PecSys was sprayed into a human nasal cavity cast model coated with a substrate containing a physiologically relevant concentration of calcium, PecSys solution was retained at the site of initial deposition with minimal redistribution, and no evidence of run-off/drip anteriorly or down the throat. In contrast, non-gelling control was significantly more mobile and consistently redistributed with run-off towards the throat. Conclusion In both models PecSys significantly reduced the potential for run-off/drip ensuring that more solution remained at the deposition site. In vivo, this enhancement of retention will provide optimum patient acceptability, modulate drug absorption and maximize the ability of drugs to be absorbed across the nasal mucosa and thus reduce variability in drug delivery. PMID:22803832

  10. Plasmid pEC156, a Naturally Occurring Escherichia coli Genetic Element That Carries Genes of the EcoVIII Restriction-Modification System, Is Mobilizable among Enterobacteria

    PubMed Central

    Werbowy, Olesia; Kaczorowski, Tadeusz

    2016-01-01

    Type II restriction-modification systems are ubiquitous in prokaryotes. Some of them are present in naturally occurring plasmids, which may facilitate the spread of these systems in bacterial populations by horizontal gene transfer. However, little is known about the routes of their dissemination. As a model to study this, we have chosen an Escherichia coli natural plasmid pEC156 that carries the EcoVIII restriction modification system. The presence of this system as well as the cis-acting cer site involved in resolution of plasmid multimers determines the stable maintenance of pEC156 not only in Escherichia coli but also in other enterobacteria. We have shown that due to the presence of oriT-type F and oriT-type R64 loci it is possible to mobilize pEC156 by conjugative plasmids (F and R64, respectively). The highest mobilization frequency was observed when pEC156-derivatives were transferred between Escherichia coli strains, Enterobacter cloacae and Citrobacter freundii representing coliform bacteria. We found that a pEC156-derivative with a functional EcoVIII restriction-modification system was mobilized in enterobacteria at a frequency lower than a plasmid lacking this system. In addition, we found that bacteria that possess the EcoVIII restriction-modification system can efficiently release plasmid content to the environment. We have shown that E. coli cells can be naturally transformed with pEC156-derivatives, however, with low efficiency. The transformation protocol employed neither involved chemical agents (e.g. CaCl2) nor temperature shift which could induce plasmid DNA uptake. PMID:26848973

  11. A Review and Analysis of the Picture Exchange Communication System (PECS) for Individuals With Autism Spectrum Disorders Using a Paradigm of Communication Competence

    ERIC Educational Resources Information Center

    Ostryn, Cheryl; Wolfe, Pamela S.; Rusch, Frank R.

    2008-01-01

    Research related to the use of the Picture Exchange Communication System (PECS) with individuals having autism spectrum disorders (ASDs) was examined using a communication competence paradigm detailed by J. C. Light (1988, 1989, 2003). Communication components were operationalized based on skills identified in ASD research. A review was conducted…

  12. The Effectiveness of the Picture Exchange Communication System (PECS) for Children with Autism Spectrum Disorder (ASD): A South African Pilot Study

    ERIC Educational Resources Information Center

    Travis, Julia; Geiger, Martha

    2010-01-01

    This study investigated the effects of introducing the Picture Exchange Communication System (PECS) on the frequency of requesting and commenting and the length of verbal utterances of two children with autism spectrum disorder (ASD) who presented with some spoken language, but limited use of language in communicative exchanges. A mixed research…

  13. Fatal pneumonia caused by Extraintestinal Pathogenic Escherichia coli (ExPEC) in a juvenile cat recovered from an animal hoarding incident.

    PubMed

    Brooks, Jason W; Roberts, Elisabeth L; Kocher, Kathleen; Kariyawasam, Subhashinie; DebRoy, Chitrita

    2013-12-27

    The current study describes isolation of Extraintestinal Pathogenic Escherichia coli (ExPEC) from a juvenile male cat that died after being rescued from an animal hoarding incident. Grossly, there was evidence of pneumonia and renal abscessation. Histologically, there was diffuse interstitial pneumonia with necrosis and necrotizing and suppurative nephritis with colonies of coccobacilli. Within the lung, kidney, and mesentery there was necrotizing and suppurative vasculitis with thrombosis and coccobacilli. E. coli strain belonging to serotype O6:H1 that carried many of the virulence genes associated with ExPEC was isolated from the lung and kidney. The cat was part of a community of approximately 60 cats that lived in a house in a residential neighborhood, in which multiple cats had died. The case was of major significance to public health, as first responders, animal health professionals, and other community members were likely exposed to ExPEC, which is known to have zoonotic potential. It is important that pet owners, animal health and public health professionals, and first responders be made aware of the potential for zoonotic diseases.

  14. Coupled optical absorption, charge carrier separation, and surface electrochemistry in surface disordered/hydrogenated TiO2 for enhanced PEC water splitting reaction.

    PubMed

    Behara, Dilip Kumar; Ummireddi, Ashok Kumar; Aragonda, Vidyasagar; Gupta, Prashant Kumar; Pala, Raj Ganesh S; Sivakumar, Sri

    2016-03-28

    The central governing factors that influence the efficiency of photoelectrochemical (PEC) water splitting reaction are photon absorption, effective charge-carrier separation, and surface electrochemistry. Attempts to improve one of the three factors may debilitate other factors and we explore such issues in hydrogenated TiO2, wherein a significant increase in optical absorption has not resulted in a significant increase in PEC performance, which we attribute to the enhanced recombination rate due to the formation of amorphization/disorderness in the bulk during the hydrogenation process. To this end, we report a methodology to increase the charge-carrier separation with enhanced optical absorption of hydrogenated TiO2. Current methodology involves hydrogenation of non-metal (N and S) doped TiO2 which comprises (1) lowering of the band gap through shifting of the valence band via less electronegative non-metal N, S-doping, (2) lowering of the conduction band level and the band gap via formation of the Ti(3+) state and oxygen vacancies by hydrogenation, and (3) material processing to obtain a disordered surface structure which favors higher electrocatalytic (EC) activity. This design strategy yields enhanced PEC activity (%ABPE = 0.38) for the N-S co-doped TiO2 sample hydrogenated at 800 °C for 24 h over possible combinations of N-S co-doped TiO2 samples hydrogenated at 500 °C/24 h, 650 °C/24 h and 800 °C/72 h. This suggests that hydrogenation at lower temperatures does not result in much increase in optical absorption and prolonged hydrogenation results in an increase in optical absorption but a decrease in charge carrier separation by forming disorderness/oxygen vacancies in the bulk. Furthermore, the difference in double layer capacitance (C(dl)) calculated from electrochemical impedance spectroscopy (EIS) measurements of these samples reflects the change in the electrochemical surface area (ECSA) and facilitates assessing the key role of surface

  15. Coupled optical absorption, charge carrier separation, and surface electrochemistry in surface disordered/hydrogenated TiO2 for enhanced PEC water splitting reaction.

    PubMed

    Behara, Dilip Kumar; Ummireddi, Ashok Kumar; Aragonda, Vidyasagar; Gupta, Prashant Kumar; Pala, Raj Ganesh S; Sivakumar, Sri

    2016-03-28

    The central governing factors that influence the efficiency of photoelectrochemical (PEC) water splitting reaction are photon absorption, effective charge-carrier separation, and surface electrochemistry. Attempts to improve one of the three factors may debilitate other factors and we explore such issues in hydrogenated TiO2, wherein a significant increase in optical absorption has not resulted in a significant increase in PEC performance, which we attribute to the enhanced recombination rate due to the formation of amorphization/disorderness in the bulk during the hydrogenation process. To this end, we report a methodology to increase the charge-carrier separation with enhanced optical absorption of hydrogenated TiO2. Current methodology involves hydrogenation of non-metal (N and S) doped TiO2 which comprises (1) lowering of the band gap through shifting of the valence band via less electronegative non-metal N, S-doping, (2) lowering of the conduction band level and the band gap via formation of the Ti(3+) state and oxygen vacancies by hydrogenation, and (3) material processing to obtain a disordered surface structure which favors higher electrocatalytic (EC) activity. This design strategy yields enhanced PEC activity (%ABPE = 0.38) for the N-S co-doped TiO2 sample hydrogenated at 800 °C for 24 h over possible combinations of N-S co-doped TiO2 samples hydrogenated at 500 °C/24 h, 650 °C/24 h and 800 °C/72 h. This suggests that hydrogenation at lower temperatures does not result in much increase in optical absorption and prolonged hydrogenation results in an increase in optical absorption but a decrease in charge carrier separation by forming disorderness/oxygen vacancies in the bulk. Furthermore, the difference in double layer capacitance (C(dl)) calculated from electrochemical impedance spectroscopy (EIS) measurements of these samples reflects the change in the electrochemical surface area (ECSA) and facilitates assessing the key role of surface

  16. Overlapped Sequence Types (STs) and Serogroups of Avian Pathogenic (APEC) and Human Extra-Intestinal Pathogenic (ExPEC) Escherichia coli Isolated in Brazil

    PubMed Central

    Maluta, Renato Pariz; Logue, Catherine Mary; Casas, Monique Ribeiro Tiba; Meng, Ting; Guastalli, Elisabete Aparecida Lopes; Rojas, Thaís Cabrera Galvão; Montelli, Augusto Cezar; Sadatsune, Teruê; de Carvalho Ramos, Marcelo; Nolan, Lisa Kay; da Silveira, Wanderley Dias

    2014-01-01

    Avian pathogenic Escherichia coli (APEC) strains belong to a category that is associated with colibacillosis, a serious illness in the poultry industry worldwide. Additionally, some APEC groups have recently been described as potential zoonotic agents. In this work, we compared APEC strains with extraintestinal pathogenic E. coli (ExPEC) strains isolated from clinical cases of humans with extra-intestinal diseases such as urinary tract infections (UTI) and bacteremia. PCR results showed that genes usually found in the ColV plasmid (tsh, iucA, iss, and hlyF) were associated with APEC strains while fyuA, irp-2, fepC sitDchrom, fimH, crl, csgA, afa, iha, sat, hlyA, hra, cnf1, kpsMTII, clpVSakai and malX were associated with human ExPEC. Both categories shared nine serogroups (O2, O6, O7, O8, O11, O19, O25, O73 and O153) and seven sequence types (ST10, ST88, ST93, ST117, ST131, ST155, ST359, ST648 and ST1011). Interestingly, ST95, which is associated with the zoonotic potential of APEC and is spread in avian E. coli of North America and Europe, was not detected among 76 APEC strains. When the strains were clustered based on the presence of virulence genes, most ExPEC strains (71.7%) were contained in one cluster while most APEC strains (63.2%) segregated to another. In general, the strains showed distinct genetic and fingerprint patterns, but avian and human strains of ST359, or ST23 clonal complex (CC), presented more than 70% of similarity by PFGE. The results demonstrate that some “zoonotic-related” STs (ST117, ST131, ST10CC, ST23CC) are present in Brazil. Also, the presence of moderate fingerprint similarities between ST359 E. coli of avian and human origin indicates that strains of this ST are candidates for having zoonotic potential. PMID:25115913

  17. Correlation between the genomic o454-nlpD region polymorphisms, virulence gene equipment and phylogenetic group of extraintestinal Escherichia coli (ExPEC) enables pathotyping irrespective of host, disease and source of isolation

    PubMed Central

    2014-01-01

    Background The mutS-rpoS intergenic region in E. coli displays a mosaic structure which revealed pathotype specific patterns. To assess the importance of this region as a surrogate marker for the identification of highly virulent extraintestinal pathogenic E. coli (ExPEC) strains we aimed to: (i) characterize the genetic diversity of the mutS gene and the o454-nlpD genomic region among 510 E. coli strains from animals and humans; (ii) delineate associations between the polymorphism of this region and features such as phylogenetic background of E. coli, pathotype, host species, clinical condition, serogroup and virulence associated genes (VAG)s; and (iii) identify the most important VAGs for classification of the o454-nlpD region. Methods Size variation in the o454-nlpD region was investigated by PCR amplification and sequencing. Phylogenetic relationships were assessed by Ecor- and Multilocus sequence- typing (MLST), and a comparative analysis between mutS gene phylogenetic tree obtained with RAxML and the MLST grouping method was performed. Correlation between o454-nlpD patterns and the features described above were analysed. In addition, the importance of 47 PCR-amplified ExPEC-related VAGs for classification of o454-nlpD patterns was investigated by means of Random Forest algorithm. Results Four main structures (patterns I-IV) of the o454-nlpD region among ExPEC and commensal E. coli strains were identified. Statistical analysis showed a positive and exclusive association between pattern III and the ExPEC strains. A strong association between pattern III and either the Ecor group B2 or the sequence type complexes known to represent the phylogenetic background of highly virulent ExPEC strains (such as STC95, STC73 and STC131) was found as well. RF analyses determined five genes (csgA, malX, chuA, sit, and vat) to be suitable to predict pattern III strains. Conclusion The significant association between pattern III and group B2 strains suggested the o454-nlp

  18. Presence of pathogenicity islands and virulence genes of extraintestinal pathogenic Escherichia coli (ExPEC) in isolates from avian organic fertilizer.

    PubMed

    Gazal, Luís Eduardo S; Puño-Sarmiento, Juan J; Medeiros, Leonardo P; Cyoia, Paula S; da Silveira, Wanderlei D; Kobayashi, Renata K T; Nakazato, Gerson

    2015-12-01

    Poultry litter is commonly used as fertilizer in agriculture. However, this poultry litter must be processed prior to use, since poultry have a large number of pathogenic microorganisms. The aims of this study were to isolate and genotypically and phenotypically characterize Escherichia coli from avian organic fertilizer. Sixty-four E. coli isolates were identified from avian organic fertilizer and characterized for ExPEC virulence factors, pathogenicity islands, phylogenetic groups, antimicrobial resistance, biofilm formation, and adhesion to HEp-2 cells. Sixty-three isolates (98.4%) showed at least one virulence gene (fimH, ecpA, sitA, traT, iutA, iroN, hlyF, ompT and iss). The predominant phylogenetic groups were groups A (59.3%) and B1 (34.3%). The pathogenicity island CFT073II (51.5%) was the most prevalent among the isolates tested. Thirty-two isolates (50%) were resistant to at least one antimicrobial agent. Approximately 90% of isolates adhered to HEp-2 cells, and the predominant pattern was aggregative adherence (74.1%). In the biofilm assay, it was observed that 75% of isolates did not produce biofilm. These results lead us to conclude that some E. coli isolates from avian organic fertilizer could be pathogenic for humans. PMID:26476087

  19. Expanding our understanding of sequence-function relationships of type II polyketide biosynthetic gene clusters: bioinformatics-guided identification of Frankiamicin A from Frankia sp. EAN1pec.

    PubMed

    Ogasawara, Yasushi; Yackley, Benjamin J; Greenberg, Jacob A; Rogelj, Snezna; Melançon, Charles E

    2015-01-01

    A large and rapidly increasing number of unstudied "orphan" natural product biosynthetic gene clusters are being uncovered in sequenced microbial genomes. An important goal of modern natural products research is to be able to accurately predict natural product structures and biosynthetic pathways from these gene cluster sequences. This requires both development of bioinformatic methods for global analysis of these gene clusters and experimental characterization of select products produced by gene clusters with divergent sequence characteristics. Here, we conduct global bioinformatic analysis of all available type II polyketide gene cluster sequences and identify a conserved set of gene clusters with unique ketosynthase α/β sequence characteristics in the genomes of Frankia species, a group of Actinobacteria with underexploited natural product biosynthetic potential. Through LC-MS profiling of extracts from several Frankia species grown under various conditions, we identified Frankia sp. EAN1pec as producing a compound with spectral characteristics consistent with the type II polyketide produced by this gene cluster. We isolated the compound, a pentangular polyketide which we named frankiamicin A, and elucidated its structure by NMR and labeled precursor feeding. We also propose biosynthetic and regulatory pathways for frankiamicin A based on comparative genomic analysis and literature precedent, and conduct bioactivity assays of the compound. Our findings provide new information linking this set of Frankia gene clusters with the compound they produce, and our approach has implications for accurate functional prediction of the many other type II polyketide clusters present in bacterial genomes. PMID:25837682

  20. The main factors of repetition: review of some results of the Pecs Center in the WHO/EURO Multicentre Study on Suicidal Behaviour.

    PubMed

    Osváth, Peter; Kelemen, Gábor; Erdös, Márta B; Vörös, Viktor; Fekete, Sándor

    2003-01-01

    The authors obtained more information about the characteristics of suicide attempters in order to examine the most important differences between those who attempted suicide for the first time (first-evers) and those who had a previous attempt (repeaters). Within the framework of the WHO/EURO Multicentre Study on Suicidal Behaviour in Pecs Center, 1158 cases of parasuicide were collected over 4 years (July 1, 1997-June 30, 2001). In the monitoring sample, 728 (62.9%) parasuicide acts were committed by women and 430 (37.1%) by men, and more than half of the attempters had made a previous attempt In the logistic regression model a higher risk of repetition was found to be related to being divorced (OR 1.84), unemployed or economically inactive (OR 1.45), and without higher education (OR 2.54). In the sample, mental disorders were the most significant risk factor for repeated attempts. The odds ratio was highest (OR 5) for personality disorders. The results may reflect (besides some factors of social destabilization) a higher importance of major mental health problems among repeaters. For this reason, more effective recognition and treatment of the underlying psychiatric and social conditions of suicide attempters has special importance to prevent future suicidal behaviour. PMID:15509139

  1. Expanding our Understanding of Sequence-Function Relationships of Type II Polyketide Biosynthetic Gene Clusters: Bioinformatics-Guided Identification of Frankiamicin A from Frankia sp. EAN1pec

    PubMed Central

    Ogasawara, Yasushi; Yackley, Benjamin J.; Greenberg, Jacob A.; Rogelj, Snezna; Melançon, Charles E.

    2015-01-01

    A large and rapidly increasing number of unstudied “orphan” natural product biosynthetic gene clusters are being uncovered in sequenced microbial genomes. An important goal of modern natural products research is to be able to accurately predict natural product structures and biosynthetic pathways from these gene cluster sequences. This requires both development of bioinformatic methods for global analysis of these gene clusters and experimental characterization of select products produced by gene clusters with divergent sequence characteristics. Here, we conduct global bioinformatic analysis of all available type II polyketide gene cluster sequences and identify a conserved set of gene clusters with unique ketosynthase α/β sequence characteristics in the genomes of Frankia species, a group of Actinobacteria with underexploited natural product biosynthetic potential. Through LC-MS profiling of extracts from several Frankia species grown under various conditions, we identified Frankia sp. EAN1pec as producing a compound with spectral characteristics consistent with the type II polyketide produced by this gene cluster. We isolated the compound, a pentangular polyketide which we named frankiamicin A, and elucidated its structure by NMR and labeled precursor feeding. We also propose biosynthetic and regulatory pathways for frankiamicin A based on comparative genomic analysis and literature precedent, and conduct bioactivity assays of the compound. Our findings provide new information linking this set of Frankia gene clusters with the compound they produce, and our approach has implications for accurate functional prediction of the many other type II polyketide clusters present in bacterial genomes. PMID:25837682

  2. Presence of pathogenicity islands and virulence genes of extraintestinal pathogenic Escherichia coli (ExPEC) in isolates from avian organic fertilizer.

    PubMed

    Gazal, Luís Eduardo S; Puño-Sarmiento, Juan J; Medeiros, Leonardo P; Cyoia, Paula S; da Silveira, Wanderlei D; Kobayashi, Renata K T; Nakazato, Gerson

    2015-12-01

    Poultry litter is commonly used as fertilizer in agriculture. However, this poultry litter must be processed prior to use, since poultry have a large number of pathogenic microorganisms. The aims of this study were to isolate and genotypically and phenotypically characterize Escherichia coli from avian organic fertilizer. Sixty-four E. coli isolates were identified from avian organic fertilizer and characterized for ExPEC virulence factors, pathogenicity islands, phylogenetic groups, antimicrobial resistance, biofilm formation, and adhesion to HEp-2 cells. Sixty-three isolates (98.4%) showed at least one virulence gene (fimH, ecpA, sitA, traT, iutA, iroN, hlyF, ompT and iss). The predominant phylogenetic groups were groups A (59.3%) and B1 (34.3%). The pathogenicity island CFT073II (51.5%) was the most prevalent among the isolates tested. Thirty-two isolates (50%) were resistant to at least one antimicrobial agent. Approximately 90% of isolates adhered to HEp-2 cells, and the predominant pattern was aggregative adherence (74.1%). In the biofilm assay, it was observed that 75% of isolates did not produce biofilm. These results lead us to conclude that some E. coli isolates from avian organic fertilizer could be pathogenic for humans.

  3. The Complete Sequence and Comparative Analysis of a Multidrug-Resistance and Virulence Multireplicon IncFII Plasmid pEC302/04 from an Extraintestinal Pathogenic Escherichia coli EC302/04 Indicate Extensive Diversity of IncFII Plasmids

    PubMed Central

    Ho, Wing Sze; Yap, Kien-Pong; Yeo, Chew Chieng; Rajasekaram, Ganeswrie; Thong, Kwai Lin

    2016-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) that causes extraintestinal infections often harbor plasmids encoding fitness traits such as resistance and virulence determinants that are of clinical importance. We determined the complete nucleotide sequence of plasmid pEC302/04 from a multidrug-resistant E. coli EC302/04 which was isolated from the tracheal aspirate of a patient in Malaysia. In addition, we also performed comparative sequence analyses of 18 related IncFIIA plasmids to determine the phylogenetic relationship and diversity of these plasmids. The 140,232 bp pEC302/04 is a multireplicon plasmid that bears three replication systems (FII, FIA, and FIB) with subtype of F2:A1:B1. The plasmid is self-transmissible with a complete transfer region. pEC302/04 also carries antibiotic resistance genes such as blaTEM−1 and a class I integron containing sul1, cml and aadA resistance genes, conferring multidrug resistance (MDR) to its host, E. coli EC302/04. Besides, two iron acquisition systems (SitABCD and IutA-IucABCD) which are the conserved virulence determinants of ExPEC-colicin V or B and M (ColV/ColBM)-producing plasmids were identified in pEC302/04. Multiple toxin-antitoxin (TA)-based addiction systems (i.e., PemI/PemK, VagC/VagD, CcdA/CcdB, and Hok/Sok) and a plasmid partitioning system, ParAB, and PsiAB, which are important for plasmid maintenance were also found. Comparative plasmid analysis revealed only one conserved gene, the repA1 as the core genome, showing that there is an extensive diversity among the IncFIIA plasmids. The phylogenetic relationship of 18 IncF plasmids based on the core regions revealed that ColV/ColBM-plasmids and non-ColV/ColBM plasmids were separated into two distinct groups. These plasmids, which carry highly diverse genetic contents, are also mosaic in nature. The atypical combination of genetic materials, i.e., the MDR- and ColV/ColBM-plasmid-virulence encoding regions in a single ExPEC plasmid is rare but of clinical

  4. Comparative Genomic Analysis Shows That Avian Pathogenic Escherichia coli Isolate IMT5155 (O2:K1:H5; ST Complex 95, ST140) Shares Close Relationship with ST95 APEC O1:K1 and Human ExPEC O18:K1 Strains

    PubMed Central

    Pan, Zihao; Hu, Lin; Wang, Shaohui; Wang, Haojin; Leung, Frederick C.; Dai, Jianjun; Fan, Hongjie

    2014-01-01

    Avian pathogenic E. coli and human extraintestinal pathogenic E. coli serotypes O1, O2 and O18 strains isolated from different hosts are generally located in phylogroup B2 and ST complex 95, and they share similar genetic characteristics and pathogenicity, with no or minimal host specificity. They are popular objects for the study of ExPEC genetic characteristics and pathogenesis in recent years. Here, we investigated the evolution and genetic blueprint of APEC pathotype by performing phylogenetic and comparative genome analysis of avian pathogenic E. coli strain IMT5155 (O2:K1:H5; ST complex 95, ST140) with other E. coli pathotypes. Phylogeny analyses indicated that IMT5155 has closest evolutionary relationship with APEC O1, IHE3034, and UTI89. Comparative genomic analysis showed that IMT5155 and APEC O1 shared significant genetic overlap/similarities with human ExPEC dominant O18:K1 strains (IHE3034 and UTI89). Furthermore, the unique PAI I5155 (GI-12) was identified and found to be conserved in APEC O2 serotype isolates. GI-7 and GI-16 encoding two typical T6SSs in IMT5155 might be useful markers for the identification of ExPEC dominant serotypes (O1, O2, and O18) strains. IMT5155 contained a ColV plasmid p1ColV5155, which defined the APEC pathotype. The distribution analysis of 10 sequenced ExPEC pan-genome virulence factors among 47 sequenced E. coli strains provided meaningful information for B2 APEC/ExPEC-specific virulence factors, including several adhesins, invasins, toxins, iron acquisition systems, and so on. The pathogenicity tests of IMT5155 and other APEC O1:K1 and O2:K1 serotypes strains (isolated in China) through four animal models showed that they were highly virulent for avian colisepticemia and able to cause septicemia and meningitis in neonatal rats, suggesting zoonotic potential of these APEC O1:K1 and O2:K1 isolates. PMID:25397580

  5. NEW TECHNOLOGY AND PEC PROCESS - COLUMBUS, GA

    EPA Science Inventory

    The presentation will discuss Columbus, Georgia’s Biosolids Flow-through Thermophilic Treatment (BFT3) Process. Site-specific equivalency requires proof. Laboratory-scale pathogen testing must exceed Class A performance criteria while simulating full scale as closely as pos...

  6. Funny and Functional Physics: PEC Nanoparticles

    NASA Astrophysics Data System (ADS)

    Cohen Stuart, Martien

    When the tendency of polyelectrolyte complexes to phase separate is judiciously combined with appropriate concepts from the realms of polymer physics and supramolecular chemistry, a wealth of novel self-assembled nanoparticles with original properties can be prepared. This presentation discusses how a high degree of complexity and functionality arises spontaneously, in the form of equilibrium structures, and how these structures can be understood from physical principles. Some promising applications are mentioned as well.

  7. Complete Sequence of pEC012, a Multidrug-Resistant IncI1 ST71 Plasmid Carrying bla CTX-M-65, rmtB, fosA3, floR, and oqxAB in an Avian Escherichia coli ST117 Strain.

    PubMed

    Pan, Yu-Shan; Zong, Zhi-Yong; Yuan, Li; Du, Xiang-Dang; Huang, Hui; Zhong, Xing-Hao; Hu, Gong-Zheng

    2016-01-01

    A 139,622-bp IncI1 ST71 conjugative plasmid pEC012 from an avian Escherichia coli D-ST117 strain was sequenced, which carried five IS26-bracketed resistance modules: IS26-fosA3-orf1-orf2-Δorf3-IS26, IS26-fip-ΔISEcp1-bla CTX-M-65-IS903D-iroN-IS26, IS26-ΔtnpR-bla TEM-1-rmtB-IS26, IS26-oqxAB-IS26, and IS26-floR-aac(3)-IV-IS26. The backbone of pEC012 was similar to that of several other IncI1 ST71 plasmids: pV408, pM105, and pC271, but these plasmids had different arrangements of multidrug resistance region. In addition, the novel ISEc57 element was identified, which is in the IS21 family. The stepwise emergence of multi-resistance regions demonstrated the accumulation of different resistance determinants through homologous recombination. To the best of our knowledge, this is the first study to identify a multidrug-resistant IncI1 ST71 plasmid carrying bla CTX-M-65, rmtB, fosA3, floR, and oqxAB in an avian E. coli ST117 strain. PMID:27486449

  8. Complete Sequence of pEC012, a Multidrug-Resistant IncI1 ST71 Plasmid Carrying blaCTX-M-65, rmtB, fosA3, floR, and oqxAB in an Avian Escherichia coli ST117 Strain

    PubMed Central

    Pan, Yu-Shan; Zong, Zhi-Yong; Yuan, Li; Du, Xiang-Dang; Huang, Hui; Zhong, Xing-Hao; Hu, Gong-Zheng

    2016-01-01

    A 139,622-bp IncI1 ST71 conjugative plasmid pEC012 from an avian Escherichia coli D-ST117 strain was sequenced, which carried five IS26-bracketed resistance modules: IS26-fosA3-orf1-orf2-Δorf3-IS26, IS26-fip-ΔISEcp1-blaCTX-M-65-IS903D-iroN-IS26, IS26-ΔtnpR-blaTEM-1-rmtB-IS26, IS26-oqxAB-IS26, and IS26-floR-aac(3)-IV-IS26. The backbone of pEC012 was similar to that of several other IncI1 ST71 plasmids: pV408, pM105, and pC271, but these plasmids had different arrangements of multidrug resistance region. In addition, the novel ISEc57 element was identified, which is in the IS21 family. The stepwise emergence of multi-resistance regions demonstrated the accumulation of different resistance determinants through homologous recombination. To the best of our knowledge, this is the first study to identify a multidrug-resistant IncI1 ST71 plasmid carrying blaCTX-M-65, rmtB, fosA3, floR, and oqxAB in an avian E. coli ST117 strain. PMID:27486449

  9. Tuning the composition of Bi x W y O nanorods towards zero bias PEC water splitting

    NASA Astrophysics Data System (ADS)

    Larson, Steven; Zhao, Yiping

    2016-06-01

    A unique co-oblique angle deposition method was used to create nanorod arrays of mixed phase Bi2O3/WO3/Bi2WO6 with varying atomic ratios of Bi to W. The effect of the tuning on the resulting nanostructures was characterized by EDX, SEM, XRD, optical transmission, specular reflection, and diffuse reflection spectroscopy. Samples with different Bi:W atomic ratio had a wide range of morphology and composition due to the surface mobility of deposited bismuth and its volume expansion during oxidation. Their photocatalytic and photoelectrochemical properties were investigated by methylene blue degradation and photo-generated current respectively. The sample with 38 at.% Bi showed the highest photodecay rates as well as the maximum photocurrent density, 4.3 μA cm‑2, at a bias potential of 600 mV versus Ag/AgCl (3M KCl); while the sample with 50 at.% Bi exhibited a high photocurrent density of 0.35 μA cm‑2 at zero bias potential, which indicates that varying the composition and mixed crystal phases of different oxides with appropriate band gaps and locations could hold the key to a visible light driven, zero bias potential, photoelectrochemical cell.

  10. Tuning the composition of Bi x W y O nanorods towards zero bias PEC water splitting

    NASA Astrophysics Data System (ADS)

    Larson, Steven; Zhao, Yiping

    2016-06-01

    A unique co-oblique angle deposition method was used to create nanorod arrays of mixed phase Bi2O3/WO3/Bi2WO6 with varying atomic ratios of Bi to W. The effect of the tuning on the resulting nanostructures was characterized by EDX, SEM, XRD, optical transmission, specular reflection, and diffuse reflection spectroscopy. Samples with different Bi:W atomic ratio had a wide range of morphology and composition due to the surface mobility of deposited bismuth and its volume expansion during oxidation. Their photocatalytic and photoelectrochemical properties were investigated by methylene blue degradation and photo-generated current respectively. The sample with 38 at.% Bi showed the highest photodecay rates as well as the maximum photocurrent density, 4.3 μA cm-2, at a bias potential of 600 mV versus Ag/AgCl (3M KCl); while the sample with 50 at.% Bi exhibited a high photocurrent density of 0.35 μA cm-2 at zero bias potential, which indicates that varying the composition and mixed crystal phases of different oxides with appropriate band gaps and locations could hold the key to a visible light driven, zero bias potential, photoelectrochemical cell.

  11. Increasing Functional Communication in Non-Speaking Preschool Children: Comparison of PECS and VOCA

    ERIC Educational Resources Information Center

    Bock, Stacey Jones; Stoner, Julia B.; Beck, Ann R.; Hanley, Laurie; Prochnow, Jessica

    2005-01-01

    For individuals who have complex communication needs and for the interventionists who work with them, the collection of empirically derived data that support the use of an intervention approach is critical. The purposes of this study were to continue building an empirically derived base of support for, and to compare the relative effectiveness of…

  12. From Premack to PECS: 25 Years of Progress in Communication Intervention for Individuals with Developmental Disabilities

    ERIC Educational Resources Information Center

    Sigafoos, Jeff

    2005-01-01

    Educational and behavioural psychologists have made major contributions to the field of communication intervention for individuals with developmental and physical disabilities. A brief personal perspective is provided on some of the major works and contributors that have shaped the field over the past 25 years. Major contributions and personal…

  13. Peace Education in the 1990s. A Guide to Five Conference Reports from PEC. Peace Education Miniprints, No. 84.

    ERIC Educational Resources Information Center

    Bjerstedt, Ake

    This bibliography lists and indexes a total of 124 papers presented during five international conferences held during the 1990s on the topic of peace education. This miniprint aims to make it easier for peace researchers and peace educators to locate conference contributions of special interest to them. The guide has been organized into three…

  14. The Picture Exchange Communication System (PECS): A Promising Method for Improving Communication Skills of Learners with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Ganz, Jennifer B.; Simpson, Richard L.; Lund, Emily M.

    2012-01-01

    Children and youth with autism spectrum disorders (ASD) and other developmental delays frequently experience deficits in functional communication. Identifying and using suitable communication enhancement and augmentative and alternative communication supports is essential to achievement of positive outcomes for these learners. This article…

  15. IUE observations of two late-type stars Bx Mon (M + pec) and TV Gem (M1 Iab)

    NASA Technical Reports Server (NTRS)

    Michalitsianos, A. G.; Hobbs, R. W.; Kafatos, M.

    1981-01-01

    The IUE observations of two late type stars BX Mon and TV Gem that reveal the emission properties in the ultraviolet of subluminous companions are discussed. Analysis of the continuum emission observed from BX Mon suggests the companion, is a middle A III star. High excitation emission lines observed between 1200 A and 2000 A that generally do not typify emission observed in either late M type variables or A type stars are also detected. It is suggested that these strong high excitation lines arise in a large volume of gas heated by nonradiation processes that could be the result of tidal interaction and mass exchange in the binary system. In contrast to stars such as BX Mon, the luminous M1 supergiant TV Gem shows unexpected intense UV continuum throughout the sensitivity range of IUE. The UV spectrum of TV Gem is characterized by intense continuum with broad absorption features detected in the short wavelength range. The analysis shows that the companion could be a B9 or A1 III-IV star. Alternate suggestions are presented for explaining the UV continuum in terms of an accretion disk in association with TV Gem.

  16. The Profile of Emotional Competence (PEC): development and validation of a self-reported measure that fits dimensions of emotional competence theory.

    PubMed

    Brasseur, Sophie; Grégoire, Jacques; Bourdu, Romain; Mikolajczak, Moïra

    2013-01-01

    Emotional Competence (EC), which refers to individual differences in the identification, understanding, expression, regulation and use of one's own emotions and those of others, has been found to be an important predictor of individuals' adaptation to their environment. Higher EC is associated with greater happiness, better mental and physical health, more satisfying social and marital relationships and greater occupational success. While it is well-known that EC (as a whole) predicts a number of important outcomes, it is unclear so far which specific competency(ies) participate(s) in a given outcome. This is because no measure of EC distinctly measures each of the five core emotional competences, separately for one's own and others' emotions. This lack of information is problematic both theoretically (we do not understand the processes at stake) and practically (we cannot develop customized interventions). This paper aims to address this issue. We developed and validated in four steps a complete (albeit short: 50 items) self-reported measure of EC: the Profile of Emotional Competence. Analyses performed on a representative sample of 5676 subjects revealed promising psychometric properties. The internal consistency of scales and subscales alike was satisfying, factorial structure was as expected, and concurrent/discriminant validity was good. PMID:23671616

  17. Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode.

    PubMed

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Wong, Po Keung; An, Taicheng; Yamashita, Hiromi; Zhao, Huijun

    2016-09-15

    Biohazards and coexisted antibiotics are two groups of emerging contaminants presented in various aquatic environments. They can pose serious threat to the ecosystem and human health. As a result, inactivation of biohazards, degradation of antibiotics, and simultaneous removal of them are highly desired. In this work, a novel photoanode with a hierarchical structured {001} facets exposed nano-size single crystals (NSC) TiO2 top layer and a perpendicularly aligned TiO2 nanotube array (NTA) bottom layer (NSC/NTA) was successfully fabricated. The morphology and facets of anatase TiO2 nanoparticles covered on the top of NTA layer could be controlled by adjusting precalcination temperature and heating rate as the pure NTA was clamped with glasses. Appropriate recalcination can timely remove surface F from {001} facets, and the photocatalytic activity of the resultant photoanode was subsequently activated. NSC/NTA photoanode fabricated under 500 °C precalcination with 20 °C min(-1) followed by 550 °C recalcination possessed highest photoelectrocatalytic efficiency to simultaneously remove bacteria and antibiotics. Results suggest that two-step calcination is necessary for fabrication of high photocatalytic activity NSC/NTA photoanode. The capability of simultaneous eradication of bacteria and antibiotics shows great potential for development of a versatile approach to effectively purify various wastewaters contaminated with complex pollutants.

  18. Effects of Zn amount on the properties of Zn-Zu2O composite films grown for PEC photoelectrodes by using electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Kim, Tae Gyoum; Lee, Hu Joong; Ryu, Hyukhyun; Lee, Won-Jae

    2015-10-01

    In this study, Zn-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates by using the electrochemical deposition method. Various amounts of Zinc (Zn) were added to grow the Zn-Cu2O composite films. We analyzed the morphological, structural, optical energy band gap and photocurrent density properties of the Zn-Cu2O composite films by using various measurements such as field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), UV-visible spectrophotometry and potentiostat/galvanostat measurements, respectively. As a result, the highest photocurrent density value of -4.04 mA/cm2 was obtained for the 30-wt% sample, which had the lowest Cu2O (111)/ ZnO (101) XRD peak intensity ratio. The highest photocurrent density value from the 30-wt% sample was approximately 2.35 times higher than that from the non-composite Cu2O film (0-wt% sample). From this study, we found that adding Zn could improve the photocurrent values of Zn-Cu2O composite films.

  19. Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode.

    PubMed

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Wong, Po Keung; An, Taicheng; Yamashita, Hiromi; Zhao, Huijun

    2016-09-15

    Biohazards and coexisted antibiotics are two groups of emerging contaminants presented in various aquatic environments. They can pose serious threat to the ecosystem and human health. As a result, inactivation of biohazards, degradation of antibiotics, and simultaneous removal of them are highly desired. In this work, a novel photoanode with a hierarchical structured {001} facets exposed nano-size single crystals (NSC) TiO2 top layer and a perpendicularly aligned TiO2 nanotube array (NTA) bottom layer (NSC/NTA) was successfully fabricated. The morphology and facets of anatase TiO2 nanoparticles covered on the top of NTA layer could be controlled by adjusting precalcination temperature and heating rate as the pure NTA was clamped with glasses. Appropriate recalcination can timely remove surface F from {001} facets, and the photocatalytic activity of the resultant photoanode was subsequently activated. NSC/NTA photoanode fabricated under 500 °C precalcination with 20 °C min(-1) followed by 550 °C recalcination possessed highest photoelectrocatalytic efficiency to simultaneously remove bacteria and antibiotics. Results suggest that two-step calcination is necessary for fabrication of high photocatalytic activity NSC/NTA photoanode. The capability of simultaneous eradication of bacteria and antibiotics shows great potential for development of a versatile approach to effectively purify various wastewaters contaminated with complex pollutants. PMID:27314556

  20. The Profile of Emotional Competence (PEC): Development and Validation of a Self-Reported Measure that Fits Dimensions of Emotional Competence Theory

    PubMed Central

    Brasseur, Sophie; Grégoire, Jacques; Bourdu, Romain; Mikolajczak, Moïra

    2013-01-01

    Emotional Competence (EC), which refers to individual differences in the identification, understanding, expression, regulation and use of one’s own emotions and those of others, has been found to be an important predictor of individuals’ adaptation to their environment. Higher EC is associated with greater happiness, better mental and physical health, more satisfying social and marital relationships and greater occupational success. While it is well-known that EC (as a whole) predicts a number of important outcomes, it is unclear so far which specific competency(ies) participate(s) in a given outcome. This is because no measure of EC distinctly measures each of the five core emotional competences, separately for one’s own and others’ emotions. This lack of information is problematic both theoretically (we do not understand the processes at stake) and practically (we cannot develop customized interventions). This paper aims to address this issue. We developed and validated in four steps a complete (albeit short: 50 items) self-reported measure of EC: the Profile of Emotional Competence. Analyses performed on a representative sample of 5676 subjects revealed promising psychometric properties. The internal consistency of scales and subscales alike was satisfying, factorial structure was as expected, and concurrent/discriminant validity was good. PMID:23671616

  1. Integrated photoelectrochemical cell and system having a liquid electrolyte

    DOEpatents

    Deng, Xunming; Xu, Liwei

    2010-07-06

    An integrated photoelectrochemical (PEC) cell generates hydrogen and oxygen from water while being illuminated with radiation. The PEC cell employs a liquid electrolyte, a multi-junction photovoltaic electrode, and a thin ion-exchange membrane. A PEC system and a method of making such PEC cell and PEC system are also disclosed.

  2. Synthesis and characterization of pectin derivative with antitumor property against Caco-2 colon cancer cells.

    PubMed

    Almeida, Elizângela A M S; Facchi, Suelen P; Martins, Alessandro F; Nocchi, Samara; Schuquel, Ivânia T A; Nakamura, Celso V; Rubira, Adley F; Muniz, Edvani C

    2015-01-22

    New pectin derivative (Pec-MA) was obtained in specific reaction conditions. The presence of maleoyl groups in Pec-MA structure was confirmed by (1)H NMR and FTIR spectroscopy. The substitution degree of Pec-MA (DS=24%) was determined by (1)H NMR. The properties of Pec-MA were investigated through WAXS, TGA/DTG, SEM and zeta potential techniques. The Pec-MA presented amorphous characteristics and higher-thermal stability compared to raw pectin (Pec). In addition, considerable morphological differences between Pec-MA and Pec were observed by SEM. The cytotoxic effect on the Caco-2 cells showed that the Pec-MA significantly inhibited the growth of colon cancer cells whereas the Pec-MA does not show any cytotoxic effect on the VERO healthy cells. This result opens new perspectives for the manufacture of biomaterials based on Pec with anti-tumor properties.

  3. Picture Exchange Communication System with Individuals with Developmental Disabilities: A Meta-Analysis of Single Subject Studies

    ERIC Educational Resources Information Center

    Hart, Stephanie L.; Banda, Devender R.

    2010-01-01

    Picture Exchange Communication System (PECS) is a picture-based communication strategy used to teach communication skills to persons with developmental disabilities including autism. This article systematically reviews 13 published single-subject studies to examine the effectiveness of PECS, the effects of PECS on speech and problem behaviors,…

  4. Understanding the Picture Exchange Communication System and Its Application in Physical Education

    ERIC Educational Resources Information Center

    Green, Amanda; Sandt, Dawn

    2013-01-01

    This article presents the Picture Exchange Communication System (PECS) and its applications in physical education. The PECS is an appropriate communication intervention for students with autism who lack functional communication skills. It is often confused with other visual support strategies, so the authors delineate the six phases of PECS and…

  5. AN UPDATE ON TECHNOLOGIES SEEKING PFRP EQUIVALENCY

    EPA Science Inventory

    This presentation will: 1) Review the mandate of the Pathogen Equivalency Committee (PEC), 2) Review the PEC's current membership (of 10), 3) Discuss how a typical application is evaluated, 4) Note where information can be found by those interested in applying to the PEC, 5) List...

  6. Exploration of the biomacromolecular interactions of an interpenetrating proteo-saccharide hydrogel network at the mucosal interface.

    PubMed

    Mashingaidze, Felix; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Maharaj, Vinesh; Buchmann, Eckhart; Ndesendo, Valence M K; Pillay, Viness

    2013-12-01

    The relationship between mucin (MUC) and pectin (PEC) was explored in an attempt to understand the biomacromolecular interactions that occur at mucosal surfaces when mucus membranes are exposed to PEC-based materials. These interactions were explored through techniques, such as attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, SEM imagery of lyophilized MUC-PEC blends, thermodynamic analysis, rheology investigations, and in silico static lattice atomistic simulations using a molecular mechanics energy relationships (MMER) approach. Three types of PEC that had different degrees of esterification and degrees of amidation were investigated at different MUC-PEC mass ratios (1:0, 1:1, 1:4, 1:9, and 0:1). The effect PEG 400 and Ca(2 +) in the MUC-PEC interactions were also studied. ATR-FTIR spectroscopy revealed broadening and strengthening of FTIR peaks at 3363 cm(-1) and between 3000-3650 cm(-1) due to stretching vibrations of the -OH, -COOH groups on MUC and PEC as well as the -N-H group on MUC. This suggested significant intra- and inter-molecular H-bonding. Morphologically, MUC-rich scaffolds were porous, thin, and multidirectional compared with the smooth, rigid, and unidirectional PEC-rich scaffolds. The Flory-Huggins interaction parameter (χ12 ) for all MUC-PEC mass ratios was negative, thus confirming MUC-PEC miscibility and interactions. UV absorbance increased with increasing relative concentration of PEC in the aqueous MUC-PEC dispersions. Furthermore, rheology investigations demonstrated synergistic enhancement in viscosity (η) and dynamic moduli upon the addition of PEG 400 and Ca(2 +) . MMER analysis revealed several key MUC-PEC interactions that corroborated well with the experimental data. Notably, higher esterification and larger mass ratios of PEC yielded greater MUC-PEC interactions.

  7. Detection of activated parietal epithelial cells on the glomerular tuft distinguishes early focal segmental glomerulosclerosis from minimal change disease.

    PubMed

    Smeets, Bart; Stucker, Fabien; Wetzels, Jack; Brocheriou, Isabelle; Ronco, Pierre; Gröne, Hermann-Josef; D'Agati, Vivette; Fogo, Agnes B; van Kuppevelt, Toin H; Fischer, Hans-Peter; Boor, Peter; Floege, Jürgen; Ostendorf, Tammo; Moeller, Marcus J

    2014-12-01

    In rodents, parietal epithelial cells (PECs) migrating onto the glomerular tuft participate in the formation of focal segmental glomerulosclerosis (FSGS) lesions. We investigated whether immunohistologic detection of PEC markers in the initial biopsies of human patients with first manifestation of idiopathic nephrotic syndrome with no immune complexes can improve the sensitivity to detect sclerotic lesions compared with standard methods. Ninety-five renal biopsies were stained for claudin-1 (PEC marker), CD44 (activated PECs), and LKIV69 (PEC matrix); 38 had been diagnosed as early primary FSGS and 57 as minimal change disease. PEC markers were detected on the tuft in 87% of the biopsies of patients diagnosed as primary FSGS. PEC markers were detected in FSGS lesions from the earliest stages of disease. In minimal change disease, no PEC activation was observed by immunohistology. However, in 25% of biopsies originally diagnosed as minimal change disease the presence of small lesions indicative of a sclerosing process were detected, which were undetectable on standard periodic acid-Schiff staining, even though only a single histologic section for each PEC marker was evaluated. Staining for LKIV69 detected lesions with the highest sensitivity. Two novel PEC markers A-kinase anchor protein 12 and annexin A3 exhibited similar sensitivity. In summary, detection of PECs on the glomerular tuft by immunostaining improves the differentiation between minimal change disease and primary FSGS and may serve to guide clinical decision making.

  8. General Characterization Methods for Photoelectrochemical Cells for Solar Water Splitting.

    PubMed

    Shi, Xinjian; Cai, Lili; Ma, Ming; Zheng, Xiaolin; Park, Jong Hyeok

    2015-10-12

    Photoelectrochemical (PEC) water splitting is a very promising technology that converts water into clean hydrogen fuel and oxygen by using solar light. However, the characterization methods for PEC cells are diverse and a systematic introduction to characterization methods for PEC cells has rarely been attempted. Unlike most other review articles that focus mainly on the material used for the working electrodes of PEC cells, this review introduces general characterization methods for PEC cells, including their basic configurations and methods for characterizing their performance under various conditions, regardless of the materials used. Detailed experimental operation procedures with theoretical information are provided for each characterization method. The PEC research area is rapidly expanding and more researchers are beginning to devote themselves to related work. Therefore, the content of this Minireview can provide entry-level knowledge to beginners in the area of PEC, which might accelerate progress in this area.

  9. General Characterization Methods for Photoelectrochemical Cells for Solar Water Splitting.

    PubMed

    Shi, Xinjian; Cai, Lili; Ma, Ming; Zheng, Xiaolin; Park, Jong Hyeok

    2015-10-12

    Photoelectrochemical (PEC) water splitting is a very promising technology that converts water into clean hydrogen fuel and oxygen by using solar light. However, the characterization methods for PEC cells are diverse and a systematic introduction to characterization methods for PEC cells has rarely been attempted. Unlike most other review articles that focus mainly on the material used for the working electrodes of PEC cells, this review introduces general characterization methods for PEC cells, including their basic configurations and methods for characterizing their performance under various conditions, regardless of the materials used. Detailed experimental operation procedures with theoretical information are provided for each characterization method. The PEC research area is rapidly expanding and more researchers are beginning to devote themselves to related work. Therefore, the content of this Minireview can provide entry-level knowledge to beginners in the area of PEC, which might accelerate progress in this area. PMID:26365789

  10. A perinatal ethics committee on abortion: process and outcome in thirty-one cases.

    PubMed

    La Puma, J; Darling, C M; Stocking, C B; Schiller, K

    1992-01-01

    The US Supreme Court's June 1992 decision to uphold most of Pennsylvania's law restricting access to abortion confirms that while abortion is still permitted in the US, it is being increasingly regulated. Individual institutions may, however, find ways to permit access to abortion. One hospital formed a mandatory, prospective perinatal ethics committee (PEC) in May 1987 to develop clinical guidelines with which to consider and decide requests by physicians for their patients seeking abortions. The authors obtained the consent of this PEC to study its membership, processes, case outcomes, and clinical decision making. Understanding PEC processes and outcomes may help other institutions to decide whether to institute similar mechanisms. Specifically, the investigators determined the backgrounds and abortion-related beliefs of PEC members and obstetric and gynecology department members, whether the PEC affects the number of abortions performed, how PEC members decide in individual cases, and whether requesting physicians find the PEC helpful. All eleven PEC members and 58 of the 65 medical staff ob/gyn physicians returned background surveys. Study results are presented. Overall, the PEC appeared to function as an affirming regulatory body for second-trimester, medically-indicated terminations and for certain personal choice terminations. Institutional interests were well-served by the PEC and with the assurance of informed consent, the interests of some patients were also well served.

  11. Bone formation of a porous Gelatin-Pectin-biphasic calcium phosphate composite in presence of BMP-2 and VEGF.

    PubMed

    Amirian, Jhaleh; Linh, Nguyen Thuy Ba; Min, Young Ki; Lee, Byong-Taek

    2015-05-01

    A composite scaffold of gelatin (Gel)-pectin (Pec)-biphasic calcium phosphate (BCP) was fabricated for the successful delivery of growth factors. Bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) were coated on the Gel-Pec-BCP surface to investigate of effect of them on bone healing. Surface morphology was investigated by scanning electron microscopy, and BCP dispersion in the hydrogel scaffolds was measured by energy dispersive X-ray spectroscopy. The results obtained from Fourier transform infrared spectroscopy showed that BMP-2 and VEGF were successfully coated on Gel-Pec-BCP hydrogel scaffolds. MC3T3-E1 preosteoblasts were cultivated on the scaffolds to investigate the effect of BMP-2 and VEGF on cell viability and proliferation. VEGF and BMP-2 loaded on Gel-Pec-BCP scaffold facilitated increased cell spreading and proliferation compared to Gel-Pec-BCP scaffolds. In vivo, bone formation was examined using rat models. Bone formation was observed in Gel-Pec-BCP/BMP-2 and Gel-Pec-BCP/VEGF scaffolds within 4 weeks, and was greatest with Gel-Pec-BCP/BMP-2 scaffolds. In vitro and in vivo results suggest that Gel-Pec-BCP/BMP-2 and Gel-Pec-BCP/VEGF scaffolds could enhance bone regeneration.

  12. Escherichia coli and urinary tract infections: the role of poultry-meat.

    PubMed

    Manges, A R

    2016-02-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) is the most common cause of community-acquired and hospital-acquired extraintestinal infections. The hypothesis that human ExPEC may have a food animal reservoir has been a topic of investigation by multiple groups around the world. Experimental studies showing the shared pathogenic potential of human ExPEC and avian pathogenic E. coli suggest that these extraintestinal E. coli may be derived from the same bacterial lineages or share common evolutionary roots. The consistent observation of specific human ExPEC lineages in poultry or poultry products, and rarely in other meat commodities, supports the hypothesis that there may be a poultry reservoir for human ExPEC. The time lag between human ExPEC acquisition (in the intestine) and infection is the fundamental challenge facing studies attempting to attribute ExPEC transmission to poultry or other environmental sources. Even whole genome sequencing efforts to address attribution will struggle with defining meaningful genetic relationships outside of a discrete food-borne outbreak setting. However, if even a fraction of all human ExPEC infections, especially antimicrobial-resistant ExPEC infections, is attributable to the introduction of multidrug-resistant ExPEC lineages through contaminated food product(s), the relevance to public health, food animal production and food safety will be significant.

  13. Some Activities of MISSE 6 Mission

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.

    2009-01-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. In this paper, a few laser and optical elements from NASA Langley Research Center (LaRC) that have been flown on MISSE 6 mission will be discussed. These items were characterized and packed inside a ruggedized Passive Experiment Container (PEC) that resembles a suitcase. The PEC was tested for survivability due to launch conditions. Subsequently, the MISSE 6 PEC was transported by the STS-123 mission to International Space Station (ISS) on March 11, 2008. The astronauts successfully attached the PEC to external handrails and opened the PEC for long term exposure to the space environment. The plan is to retrieve the MISSE 6 PEC by STS-128 mission in August 2009.

  14. Cationic and anionic polyelectrolyte complexes of xylan and chitosan. Interaction with lignocellulosic surfaces.

    PubMed

    Mocchiutti, Paulina; Schnell, Carla N; Rossi, Gerardo D; Peresin, María S; Zanuttini, Miguel A; Galván, María V

    2016-10-01

    Cationic (CatPECs) and anionic (AnPECs) polyelectrolyte complexes from xylan and chitosan were formed, characterized and adsorbed onto unbleached fibers for improving the papermaking properties. They were prepared at a level of 30% of neutralization charge ratio by modifying the order of addition of polyelectrolytes and the ionic strength (0.01N and 0.1N NaCl). The charge density, colloidal stability and particle size of polyelectrolyte complexes (PECs) was measured using polyelectrolyte titration method, Turbiscan and Zetasizer Nano equipments, respectively. All the complexes were stable even after seven days from PEC formation. DRIFT spectra of complexes were also analyzed. The adsorption behavior of them onto cellulose nanofibrils model surfaces was studied using quartz crystal microbalance with dissipation monitoring, and surface plasmon resonance. It was found that the PEC layers were viscoelastic and highly hydrated. Finally, it is shown that the adsorbed PECs onto cellulosic fibers markedly improved the tensile and crushing strengths of paper.

  15. General boundary mapping method and its application in designing an arbitrarily shaped perfect electric conductor reshaper.

    PubMed

    Guan, Jianguo; Li, Wei; Wang, Wei; Fu, Zhengyi

    2011-09-26

    A general boundary mapping method is proposed to enable the designing of various transformation devices with arbitrary shapes by reducing the traditional space-to-space mapping to boundary-to-boundary mapping. The method also makes the designing of complex-shaped transformation devices more feasible and flexible. Using the boundary mapping method, an arbitrarily shaped perfect electric conductor (PEC) reshaping device, which is called a "PEC reshaper," is demonstrated to visually reshape a PEC with an arbitrary shape to another arbitrary one. Unlike the previously reported simple PEC reshaping devices, the arbitrarily shaped PEC reshaper designed here does not need to share a common domain. Moreover, the flexibilities of the boundary mapping method are expected to inspire some novel PEC reshapers with attractive new functionalities.

  16. MicroRNA-193a Regulates the Transdifferentiation of Human Parietal Epithelial Cells toward a Podocyte Phenotype

    PubMed Central

    Kietzmann, Leonie; Guhr, Sebastian S.O.; Meyer, Tobias N.; Ni, Lan; Sachs, Marlies; Panzer, Ulf; Stahl, Rolf A.K.; Saleem, Moin A.; Kerjaschki, Dontscho; Gebeshuber, Christoph A.

    2015-01-01

    Parietal epithelial cells have been identified as potential progenitor cells in glomerular regeneration, but the molecular mechanisms underlying this process are not fully defined. Here, we established an immortalized polyclonal human parietal epithelial cell (hPEC) line from naive human Bowman’s capsule cells isolated by mechanical microdissection. These hPECs expressed high levels of PEC-specific proteins and microRNA-193a (miR-193a), a suppressor of podocyte differentiation through downregulation of Wilms’ tumor 1 in mice. We then investigated the function of miR-193a in the establishment of podocyte and PEC identity and determined whether inhibition of miR-193a influences the behavior of PECs in glomerular disease. After stable knockdown of miR-193a, hPECs adopted a podocyte-like morphology and marker expression, with decreased expression levels of PEC markers. In mice, inhibition of miR-193a by complementary locked nucleic acids resulted in an upregulation of the podocyte proteins synaptopodin and Wilms’ tumor 1. Conversely, overexpression of miR-193a in vivo resulted in the upregulation of PEC markers and the loss of podocyte markers in isolated glomeruli. Inhibition of miR-193a in a mouse model of nephrotoxic nephritis resulted in reduced crescent formation and decreased proteinuria. Together, these results show the establishment of a human PEC line and suggest that miR-193a functions as a master switch, such that glomerular epithelial cells with high levels of miR-193a adopt a PEC phenotype and cells with low levels of miR-193a adopt a podocyte phenotype. miR-193a–mediated maintenance of PECs in an undifferentiated reactive state might be a prerequisite for PEC proliferation and migration in crescent formation. PMID:25270065

  17. A brief review of models of DC-DC power electronic converters for analysis of their stability

    NASA Astrophysics Data System (ADS)

    Siewniak, Piotr; Grzesik, Bogusław

    2014-10-01

    A brief review of models of DC-DC power electronic converters (PECs) is presented in this paper. It contains the most popular, continuous-time and discrete-time models used for PEC simulation, design, stability analysis and other applications. Both large-signal and small-signal models are considered. Special attention is paid to models that are used in practice for the analysis of the global and local stability of PECs.

  18. Triggered Release of Encapsulated Cargo from Photoresponsive Polyelectrolyte Nanocomplexes

    PubMed Central

    2016-01-01

    Combining the numerous advantages of using light as a stimulus, simple free radical random copolymerization, and the easy, all-aqueous preparation of polyelectrolyte complexes (PECs), we prepared photolabile PEC nanoparticles and demonstrated their rapid degradation under UV light. As a proof of concept demonstration, the dye Nile Red was encapsulated in the PECs and successfully released into the surrounding solution as the polyelectrolyte nanocomplex carriers dissolved upon light irradiation. PMID:27526052

  19. Rational design of semiconductors for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Wei, Su-Huai

    2013-12-01

    Using first-principles method as a tool, we discuss the general strategies for the rational design of semiconductors to simultaneously meet all of requirements for high-efficiency, solar-driven photoelectrochemical (PEC) water-splitting devices. Our studies demonstrate that theoretical calculations, which provided deep understanding of the underlying physics behind these PEC materials, can greatly accelerate scientific discovery of new PEC materials in this exciting field.

  20. A Multiepitope Subunit Vaccine Conveys Protection against Extraintestinal Pathogenic Escherichia coli in Mice▿ †

    PubMed Central

    Wieser, Andreas; Romann, Eva; Magistro, Giuseppe; Hoffmann, Christiane; Nörenberg, Dominik; Weinert, Kirsten; Schubert, Sören

    2010-01-01

    Infections due to extraintestinal pathogenic Escherichia coli (ExPEC) are common in humans and animals and include urinary tract infections (from uropathogenic E. coli [UPEC]), septicemia, and wound infections. These infections result in significant morbidity and mortality and in high health care costs. In view of the increasing number of ExPEC infections and the ever-growing antibiotic resistance capability of ExPEC isolates, preventive measures such as an effective vaccine against ExPEC are desirable. An ExPEC vaccine may be cost-effective for select patient groups. Previous vaccine candidates consisted of single target proteins or whole ExPEC cells. Here we describe a subunit vaccine against ExPEC which is based on immunodominant epitopes of the virulence-associated ExPEC proteins FyuA, IroN, ChuA, IreA, Iha, and Usp. Using a novel approach of computer-aided design, two completely artificial genes were created, both encoding eight peptide domains derived from these ExPEC proteins. The recombinant expression of these two genes resulted in a protein vaccine directed against ExPEC but not against commensal E. coli of the gut flora. In mice, the vaccine was highly immunogenic, eliciting both strong humoral and cellular immune responses. Nasal application resulted in high secretory immunoglobulin A (sIgA) production, which was detectable on the mucosal surface of the urogenital tract. Finally, it conveyed protection, as shown by a significant reduction of bacterial load in a mouse model of ExPEC peritonitis. This study provides evidence that a novel vaccine design encompassing distinct epitopes of virulence-associated ExPEC proteins may represent a means for providing a protective and pathogen-specific vaccine. PMID:20498257

  1. Development and in vitro evaluation of a buccal drug delivery system based on preactivated thiolated pectin.

    PubMed

    Hauptstein, Sabine; Hintzen, Fabian; Müller, Christiane; Ohm, Moritz; Bernkop-Schnürch, Andreas

    2014-11-01

    The aim of this study was to evaluate the potential of preactivated thiolated pectin (Pec-Cys-MNA) for buccal drug delivery. Therefore, a gel formulation containing this novel polymer and the model drug lidocaine was prepared and investigated in vitro in terms of rheology, mucoadhesion, swelling behavior and drug release in comparison to formulations based on pectin (Pec) and thiolated pectin (Pec-Cys). Both pectin derivatives showed gel formation without addition of any other excipient due to self-crosslinking thiol groups. Under same conditions, pectin did not show gel formation. Viscosity of Pec-Cys-based formulation increased 92-fold and viscosity of Pec-Cys-MNA-based formulations by 4958-fold compared to pectin-based formulation. Gels did not dissolve in aqueous environment during several hours and were able to take up water. Mucoadhesion of pectin on buccal tissue could be improved significantly, value of total work of adhesion increased in the following rank order: Pec-Cys-MNA > Pec-Cys > Pec. The retention time of a model drug incorporated in gel formulations on buccal mucosa under continuous rinsing with phosphate-buffered saline was prolonged, after 1.5 h 3-fold higher amount of a model drug was to be found on tissue after application of Pec-Cys-MNA-based formulation compared to pectin-based and 2-fold compared to Pec-Cys-based formulation. The Pec-Cys-MNA-based gel showed a more sustained release of lidocaine than Pec-Cys-based gel, whereas pectin solution revealed an immediate release. According to these results, the self-crosslinking pectin-derivative is a promising tool for buccal application.

  2. Simultaneous glucose sensing and biohydrogen evolution from direct photoelectrocatalytic glucose oxidation on robust Cu₂O-TiO₂ electrodes.

    PubMed

    Devadoss, Anitha; Sudhagar, P; Ravidhas, C; Hishinuma, Ryota; Terashima, Chiaki; Nakata, Kazuya; Kondo, Takeshi; Shitanda, Isao; Yuasa, Makoto; Fujishima, Akira

    2014-10-21

    We report simultaneous photoelectrocatalytic (PEC) glucose sensing and biohydrogen generation for the first time from the direct PEC oxidation of glucose at multifunctional and robust Cu2O-TiO2 photocatalysts. Striking improvement of 30% in overall H2 gas evolution (∼122 μmol h(-1) cm(-2)) by photoholes assisted glucose oxidation opens a new platform in solar-driven PEC biohydrogen generation.

  3. Characterization of Extraintestinal Pathogenic Escherichia coli isolated from retail poultry meats from Alberta, Canada.

    PubMed

    Aslam, Mueen; Toufeer, Mehdi; Narvaez Bravo, Claudia; Lai, Vita; Rempel, Heidi; Manges, Amee; Diarra, Moussa Sory

    2014-05-01

    Extraintestinal Pathogenic Escherichia coli (ExPEC) have the potential to spread through fecal waste resulting in the contamination of both farm workers and retail poultry meat in the processing plants or environment. The objective of this study was to characterize ExPEC from retail poultry meats purchased from Alberta, Canada and to compare them with 12 human ExPEC representatives from major ExPEC lineages. Fifty-four virulence genes were screened by a set of multiplex PCRs in 700 E. coli from retail poultry meat samples. ExPEC was defined as the detection of at least two of the following virulence genes: papA/papC, sfa, kpsMT II and iutA. Genetic relationships between isolates were determined using pulsed field gel electrophoresis (PFGE). Fifty-nine (8.4%) of the 700 poultry meat isolates were identified as ExPEC and were equally distributed among the phylogenetic groups A, B1, B2 and D. Isolates of phylogenetic group A possessed up to 12 virulence genes compared to 24 and 18 genes in phylogenetic groups B2 and D, respectively. E. coli identified as ExPEC and recovered from poultry harbored as many virulence genes as those of human isolates. In addition to the iutA gene, siderophore-related iroN and fyuA were detected in combination with other virulence genes including those genes encoding for adhesion, protectin and toxin while the fimH, ompT, traT, uidA and vat were commonly detected in poultry ExPEC. The hemF, iss and cvaC genes were found in 40% of poultry ExPEC. All human ExPEC isolates harbored concnf (cytotoxic necrotizing factor 1 altering cytoskeleton and causing necrosis) and hlyD (hemolysin transport) genes which were not found in poultry ExPEC. PFGE analysis showed that a few poultry ExPEC isolates clustered with human ExPEC isolates at 55-70% similarity level. Comparing ExPEC isolated from retail poultry meats provides insight into their virulence potential and suggests that poultry associated ExPEC may be important for retail meat safety

  4. Characterization of Indigoidine Biosynthetic Genes in Erwinia chrysanthemi and Role of This Blue Pigment in Pathogenicity

    PubMed Central

    Reverchon, Sylvie; Rouanet, Carine; Expert, Dominique; Nasser, William

    2002-01-01

    In the plant-pathogenic bacterium Erwinia chrysanthemi production of pectate lyases, the main virulence determinant, is modulated by a complex network involving several regulatory proteins. One of these regulators, PecS, also controls the synthesis of a blue pigment identified as indigoidine. Since production of this pigment is cryptic in the wild-type strain, E. chrysanthemi ind mutants deficient in indigoidine synthesis were isolated by screening a library of Tn5-B21 insertions in a pecS mutant. These ind mutations were localized close to the regulatory pecS-pecM locus, immediately downstream of pecM. Sequence analysis of this DNA region revealed three open reading frames, indA, indB, and indC, involved in indigoidine biosynthesis. No specific function could be assigned to IndA. In contrast, IndB displays similarity to various phosphatases involved in antibiotic synthesis and IndC reveals significant homology with many nonribosomal peptide synthetases (NRPS). The IndC product contains an adenylation domain showing the signature sequence DAWCFGLI for glutamine recognition and an oxidation domain similar to that found in various thiazole-forming NRPS. These data suggest that glutamine is the precursor of indigoidine. We assume that indigoidine results from the condensation of two glutamine molecules that have been previously cyclized by intramolecular amide bond formation and then dehydrogenated. Expression of ind genes is strongly derepressed in the pecS background, indicating that PecS is the main regulator of this secondary metabolite synthesis. DNA band shift assays support a model whereby the PecS protein represses indA and indC expression by binding to indA and indC promoter regions. The regulatory link, via pecS, between indigoidine and virulence factor production led us to explore a potential role of indigoidine in E. chrysanthemi pathogenicity. Mutants impaired in indigoidine production were unable to cause systemic invasion of potted Saintpaulia ionantha

  5. Characterization of indigoidine biosynthetic genes in Erwinia chrysanthemi and role of this blue pigment in pathogenicity.

    PubMed

    Reverchon, Sylvie; Rouanet, Carine; Expert, Dominique; Nasser, William

    2002-02-01

    In the plant-pathogenic bacterium Erwinia chrysanthemi production of pectate lyases, the main virulence determinant, is modulated by a complex network involving several regulatory proteins. One of these regulators, PecS, also controls the synthesis of a blue pigment identified as indigoidine. Since production of this pigment is cryptic in the wild-type strain, E. chrysanthemi ind mutants deficient in indigoidine synthesis were isolated by screening a library of Tn5-B21 insertions in a pecS mutant. These ind mutations were localized close to the regulatory pecS-pecM locus, immediately downstream of pecM. Sequence analysis of this DNA region revealed three open reading frames, indA, indB, and indC, involved in indigoidine biosynthesis. No specific function could be assigned to IndA. In contrast, IndB displays similarity to various phosphatases involved in antibiotic synthesis and IndC reveals significant homology with many nonribosomal peptide synthetases (NRPS). The IndC product contains an adenylation domain showing the signature sequence DAWCFGLI for glutamine recognition and an oxidation domain similar to that found in various thiazole-forming NRPS. These data suggest that glutamine is the precursor of indigoidine. We assume that indigoidine results from the condensation of two glutamine molecules that have been previously cyclized by intramolecular amide bond formation and then dehydrogenated. Expression of ind genes is strongly derepressed in the pecS background, indicating that PecS is the main regulator of this secondary metabolite synthesis. DNA band shift assays support a model whereby the PecS protein represses indA and indC expression by binding to indA and indC promoter regions. The regulatory link, via pecS, between indigoidine and virulence factor production led us to explore a potential role of indigoidine in E. chrysanthemi pathogenicity. Mutants impaired in indigoidine production were unable to cause systemic invasion of potted Saintpaulia ionantha

  6. Modeling the inactivatin of Escherichia coli 0157:H7 and uropathogenic E. coli in ground beef by high pressure processing and citral

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compared the resistance of iPEC (O157:H7) to UPEC in ground beef using High Pressure Processing...

  7. Potential of surface-eroding poly(ethylene carbonate) for drug delivery to macrophages.

    PubMed

    Bohr, Adam; Water, Jorrit J; Wang, Yingya; Arnfast, Lærke; Beck-Broichsitter, Moritz

    2016-09-25

    Films composed of poly(ethylene carbonate) (PEC), a biodegradable polymer, were compared with poly(lactide-co-glycolide) (PLGA) films loaded with and without the tuberculosis drug rifampicin to study the characteristics and performance of PEC as a potential carrier for controlled drug delivery to macrophages. All drug-loaded PLGA and PEC films were amorphous indicating good miscibility of the drug in the polymers, even at high drug loading (up to 50wt.%). Polymer degradation studies showed that PLGA degraded slowly via bulk erosion while PEC degraded more rapidly and near-linearly via enzyme mediated surface erosion (by cholesterol esterase). Drug release studies performed with polymer films indicated a diffusion/erosion dependent delivery behavior for PLGA while an almost zero-order drug release profile was observed from PEC due to the controlled polymer degradation process. When exposed to polymer degradation products the murine macrophage cell line J774A.1 showed less susceptibility to PEC than to PLGA. However, when seeding the macrophages on PLGA and PEC films no relevant difference in cell proliferation/growth kinetics was observed. Overall, this study emphasizes that PEC is an attractive polymer for controlled drug release and could provide superior performance to PLGA for some drug delivery applications including the treatment of macrophage infections. PMID:27492019

  8. Photoelectrochemical Solar Cells.

    ERIC Educational Resources Information Center

    McDevitt, John T.

    1984-01-01

    This introduction to photoelectrochemical (PEC) cells reviews topics pertaining to solar energy conversion and demonstrates the ease with which a working PEC cell can be prepared with n-type silicon as the photoanode and a platinum counter electrode (both immersed in ethanolic ferrocene/ferricenium solutions). Experiments using the cell are…

  9. Action pattern of Valencia orange PME de-esterification of high methoxyl pectin and characterization of modified pectins.

    PubMed

    Kim, Yookyung; Teng, Quincy; Wicker, Louise

    2005-12-12

    Valencia pectinmethylesterase (PME) fractions, B-PME, containing 36 and 13 kDa protein bands and U-PME, containing a 36 and 27 kDa protein bands, were used to de-esterify original pectin (O-Pec) from 73% degree of esterification (%DE) to 63% (B-Pec) and 61% DE (U-Pec), respectively. Most O-Pec eluted from ion exchange chromatography at low salt concentration and a smaller component eluted at higher ionic strength. B-Pec and U-Pec eluted as one broad peak at higher ionic strength. PME modification did not change molecular weight: O-pectin (134,000 g/mol), U-Pec (133,850 g/mol), and B-Pec (132,250 g/mol). The NMR signal of GG and GGG increased after modification, whereas the signal of EE and EEE decreased. The negative zeta-potential increased with pH for all pectins. U-PME and B-PME created differently modified pectins that vary in degree and length of multiple attacks and fraction of the pectin population that was modified.

  10. FROM CONCEPT TO EQUIVALENCY: THE 503 REGULATIONS AND THE PATHOGEN EQUIVALENCY COMMITTEE (PAPER)

    EPA Science Inventory

    Since its creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing innovative and alternative sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether t...

  11. FROM CONCEPT TO EQUIVALENCY: THE 503 REGULATIONS AND THE PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    Since its creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing innovative and alternative sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether t...

  12. Insight into fractal self-assembly of poly(diallyldimethylammonium chloride)/sodium carboxymethyl cellulose polyelectrolyte complex nanoparticles.

    PubMed

    Zhao, Qiang; An, Quanfu; Qian, Jinwen; Wang, Xuesan; Zhou, Yang

    2011-12-22

    Poly(diallyldimethylammonium chloride)-sodium carboxymethyl cellulose polyelectrolyte complexes (PDDA-CMCNa PECs) solids were prepared and dispersed in NaOH aqueous solution. Self-assembly of PECs nanoparticles during the solvent evaporation was examined by field emission electron microscopy (FESEM), atomic force microscopy (AFM), and fractal dimension analysis. It was found that tree-shaped fractal patterns formed after the solvent (water) was dried at ambient temperatures, and the fractal pattern is composed of needle-shaped PEC aggregate (PECA) nanoparticles. Time-dependent FESEM observation revealed that the fractal pattern started with the formation of initial nucleon and it is growing, during which the diffusion limited aggregation (DLA) mechanism revealed and made the pattern branched. Physical insight into the DLA mechanism was discussed in detail. Effects of PEC concentrations, PEC compositions, solvent evaporation temperatures, pH of PEC dispersion, and chemical structures of PECs on the formation of self-assembled fractal pattern were studied. Generally, it was found that the morphologies, charge characters of PEC particles, and the solvent evaporation conditions play important roles during the fractal self-assembly process. PMID:22098094

  13. Potential of surface-eroding poly(ethylene carbonate) for drug delivery to macrophages.

    PubMed

    Bohr, Adam; Water, Jorrit J; Wang, Yingya; Arnfast, Lærke; Beck-Broichsitter, Moritz

    2016-09-25

    Films composed of poly(ethylene carbonate) (PEC), a biodegradable polymer, were compared with poly(lactide-co-glycolide) (PLGA) films loaded with and without the tuberculosis drug rifampicin to study the characteristics and performance of PEC as a potential carrier for controlled drug delivery to macrophages. All drug-loaded PLGA and PEC films were amorphous indicating good miscibility of the drug in the polymers, even at high drug loading (up to 50wt.%). Polymer degradation studies showed that PLGA degraded slowly via bulk erosion while PEC degraded more rapidly and near-linearly via enzyme mediated surface erosion (by cholesterol esterase). Drug release studies performed with polymer films indicated a diffusion/erosion dependent delivery behavior for PLGA while an almost zero-order drug release profile was observed from PEC due to the controlled polymer degradation process. When exposed to polymer degradation products the murine macrophage cell line J774A.1 showed less susceptibility to PEC than to PLGA. However, when seeding the macrophages on PLGA and PEC films no relevant difference in cell proliferation/growth kinetics was observed. Overall, this study emphasizes that PEC is an attractive polymer for controlled drug release and could provide superior performance to PLGA for some drug delivery applications including the treatment of macrophage infections.

  14. Parental Empowerment in Mexico: Randomized Experiment of the "Apoyos a La Gestion Escolar (Age)" Program in Rural Primary Schools in Mexico

    ERIC Educational Resources Information Center

    Gertler, Paul; Patrinos, Harry Anthony; Rodriguez-Oreggia, Eduardo

    2012-01-01

    Previous evaluations from Mexico are limited. The urban school-based management program, Programa Escuelas de Calidad (PEC), was analyzed using panel data regression analysis and propensity score matching. Participation in PEC is found to lead to decreases in dropout, failure and repetition rates. An evaluation of the rural parental empowerment…

  15. Using the Picture Exchange Communication System with Students with Visual Impairment

    ERIC Educational Resources Information Center

    Ivy, Sarah E.; Hatton, Deborah D.; Hooper, Jonathan D.

    2014-01-01

    Students with visual impairment (VI) were taught to request using the Picture Exchange Communication System (PECS) and tangible symbols. Participants were four males with additional disabilities, 5 to 11 years old, who had little to no functional vision. A functional relation between PECS Phase 1 and requesting was established using a multiple…

  16. The Effectiveness of the "Picture Exchange Communication System" with Nonspeaking Adults

    ERIC Educational Resources Information Center

    Stoner, Julia B.; Beck, Ann R.; Bock, Stacey Jones; Hickey, Katherine; Kosuwan, Kullaya; Thompson, James R.

    2006-01-01

    "Picture Exchange Communication System" (PECS) training was implemented with 5 nonspeaking adults with mental retardation who were not currently using any type of functional communication system. A modified ABAB, single-subject design was used to assess the effectiveness of PECS in enhancing the functional communication skills of these…

  17. Quantitative Synthesis and Component Analysis of Single-Participant Studies on the Picture Exchange Communication System

    ERIC Educational Resources Information Center

    Tincani, Matt; Devis, Kathryn

    2011-01-01

    The "Picture Exchange Communication System" (PECS) has emerged as the augmentative communication intervention of choice for individuals with autism spectrum disorder (ASD), with a supporting body of single-participant studies. This report describes a meta-analysis of 16 single-participant studies on PECS with percentage of nonoverlapping data…

  18. A Review of the Efficacy of the Picture Exchange Communication System Intervention

    ERIC Educational Resources Information Center

    Preston, Deborah; Carter, Mark

    2009-01-01

    The Picture Exchange Communication System (PECS) is a communication program that has become widely used, especially with children with autism. This paper reports the results of a review of the empirical literature on PECS. A descriptive review is provided of the 27 studies identified, which included randomized controlled trials (RCTs), other group…

  19. Effectiveness of the Picture Exchange Communication System as a Functional Communication Intervention for Individuals with Autism Spectrum Disorders: A Practice-Based Research Synthesis

    ERIC Educational Resources Information Center

    Tien, Kai-Chien

    2008-01-01

    This research synthesis verifies the effectiveness of the Picture Exchange Communication System (PECS) for improving the functional communication skills of individuals with autism spectrum disorders (ASD). The research synthesis was focused on the degree to which variations in PECS training are associated with variations in functional…

  20. 77 FR 69591 - President's Export Council: Meeting of the President's Export Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-20

    ... Council Web site at http://trade.gov/pec . DATES: December 6, 2012 at 8:00 a.m. (ET). ADDRESSES: The President's Export Council meeting will be broadcast via live webcast on the Internet at http://whitehouse... electronically via the President's Export Council Web site at http://trade.gov/pec/peccomments.asp ; or...

  1. A Communication-Based Intervention for Nonverbal Children with Autism: What Changes? Who Benefits?

    ERIC Educational Resources Information Center

    Gordon, Kate; Pasco, Greg; McElduff, Fiona; Wade, Angie; Howlin, Pat; Charman, Tony

    2011-01-01

    Objective: This article examines the form and function of spontaneous communication and outcome predictors in nonverbal children with autism following classroom-based intervention (Picture Exchange Communication System [PECS] training). Method: 84 children from 15 schools participated in a randomized controlled trial (RCT) of PECS (P. Howlin, R.…

  2. Possible role of the Ec peptide of IGF-1Ec in cartilage repair

    PubMed Central

    Armakolas, Nikolaos; Dimakakos, Andreas; Armakolas, Athanasios; Antonopoulos, Athanasios; Koutsilieris, Michael

    2016-01-01

    The Ec peptide (PEc) of insulin-like growth factor 1 Ec (IGF-1Ec) induces human mesenchymal stem cell (hMSC) mobilization and activates extracellular signal-regulated kinase 1/2 (ERK 1/2) in various cells. The aim of the present study was to examine the effects of PEc on the mobilization and differentiation of hMSCs, as well as the possibility of its implementation in combination with transforming growth factor β1 (TGF-β1) for cartilage repair. The effects of the exogenous administration of PEc and TGF-β1, alone and in combination, on hMSCs were assessed using a trypan blue assay, reverse transcription-quantitative polymerase chain reaction, western blot analysis, Alcian blue staining, wound healing assays and migration/invasion assays. It was determined that PEc is involved in the differentiation process of hMSCs towards hyaline cartilage. Treatment of hMSCs with either PEc, TGF-β1 or both, demonstrated comparable cartilage matrix deposition. Furthermore, treatment with PEc in combination with TGF-β1 was associated with a significant increase in hMSC mobilization when compared with treatment with TGF-β1 or PEc alone (P<0.05). Thus, PEc appears to facilitate in vitro hMSC mobilization and differentiation towards chondrocytes, enhancing the role of TGF-β1. PMID:27571686

  3. Possible role of the Ec peptide of IGF‑1Ec in cartilage repair.

    PubMed

    Armakolas, Nikolaos; Dimakakos, Andreas; Armakolas, Athanasios; Antonopoulos, Athanasios; Koutsilieris, Michael

    2016-10-01

    The Ec peptide (PEc) of insulin-like growth factor 1 Ec (IGF-1Ec) induces human mesenchymal stem cell (hMSC) mobilization and activates extracellular signal‑regulated kinase 1/2 (ERK 1/2) in various cells. The aim of the present study was to examine the effects of PEc on the mobilization and differentiation of hMSCs, as well as the possibility of its implementation in combination with transforming growth factor β1 (TGF‑β1) for cartilage repair. The effects of the exogenous administration of PEc and TGF‑β1, alone and in combination, on hMSCs were assessed using a trypan blue assay, reverse transcription-quantitative polymerase chain reaction, western blot analysis, Alcian blue staining, wound healing assays and migration/invasion assays. It was determined that PEc is involved in the differentiation process of hMSCs towards hyaline cartilage. Treatment of hMSCs with either PEc, TGF‑β1 or both, demonstrated comparable cartilage matrix deposition. Furthermore, treatment with PEc in combination with TGF‑β1 was associated with a significant increase in hMSC mobilization when compared with treatment with TGF‑β1 or PEc alone (P<0.05). Thus, PEc appears to facilitate in vitro hMSC mobilization and differentiation towards chondrocytes, enhancing the role of TGF‑β1. PMID:27571686

  4. Extraintestinal pathogenic Escherichia coli.

    PubMed

    Smith, James L; Fratamico, Pina M; Gunther, Nereus W

    2007-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) possesses virulence traits that allow it to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgical site infections, as well as infections in other extraintestinal locations. ExPEC-induced diseases represent a large burden in terms of medical costs and productivity losses. In addition to human illnesses, ExPEC strains also cause extraintestinal infections in domestic animals and pets. A commonality of virulence factors has been demonstrated between human and animal ExPEC, suggesting that the organisms are zoonotic pathogens. ExPEC strains have been isolated from food products, in particular from raw meats and poultry, indicating that these organisms potentially represent a new class of foodborne pathogens. This review discusses various aspects of ExPEC, including its presence in food products, in animals used for food or as companion pets; the diseases ExPEC can cause; and the virulence factors and virulence mechanisms that cause disease.

  5. Design of a visible light driven photo-electrochemical/electro-Fenton coupling oxidation system for wastewater treatment.

    PubMed

    Ding, Xing; Ai, Zhihui; Zhang, Lizhi

    2012-11-15

    In this study, we report on a photo-electrochemical/electro-Fenton oxidation (PEC/EF) system by coupling visible light driven photo-electrochemical oxidation (PEC) and electro-Fenton oxidation (EF) in an undivided cell. Bi2WO6 nanoplates deposited on FTO glass (Bi2WO6/FTO) and Fe@Fe2O3 core-shell nanowires supported on activated carbon fiber (Fe@Fe2O3/ACF) were used as the anode and the cathode in the PEC/EF system, respectively. This novel PEC/EF system showed much higher activity than the single PEC and EF systems on degradation of rhodamine B in aqueous solution at natural pH. Moreover, the degradation and the instantaneous current efficiencies of the PEC/EF system were increased by 154% and 26% in comparison with the sum of those of single PEC and EF systems, respectively. These significant enhancements could be attributed to the synergetic effect from better separation of photo-generated carriers in the photo-anode and the transfer of photo-electrons to the oxygen diffusion cathode to generate more electro-generated H2O2 and hydroxyl radicals on the Fenton cathode. The better separation of photo-generated carriers contribute more to the overall degradation enhancement than the photo-electrons generated H2O2 and the subsequent Fenton reaction on the cathode during the PEC/EF process. PMID:23017238

  6. Modeling the inactivation of Escherichia coli 0157:H7 and uropathogenic E.coli in ground chicken by high pressure processing and thymol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compare the resistance of iPEC (O157:H7) to UPEC in chicken meat using High Pressure Processing...

  7. DNA Labeling Generates a Unique Amplification Probe for Sensitive Photoelectrochemical Immunoassay of HIV-1 p24 Antigen.

    PubMed

    Zhao, Wei-Wei; Han, Ying-Mei; Zhu, Yuan-Cheng; Zhang, Nan; Xu, Jing-Juan; Chen, Hong-Yuan

    2015-06-01

    Photoelectrochemical (PEC) immunoassay is an attractive methodology as it allows for an elegant and sensitive protein assay. However, advanced PEC immunoassay remains challenging and the established amplifications rely almost exclusively on the labeling of various enzymes, which usually suffer the inferior stabilities. Here we report the development and validation of the DNA labeling that leads to a unique amplification probe for the sensitive PEC immunoassay of HIV-1 capsid protein, p24 antigen, an important biomarker of human immune deficiency virus (HIV). Following the sandwich immunobinding, the DNA tags could be released and the subsequent dipurinization of the oligonucleotide strands enables the easy oxidation of free nucleobases at a CdTe quantum dots (QDs) modified ITO transducer. Such DNA tags induced PEC amplification and readout permits the exquisite assay of HIV-1 p24 antigen with high sensitivity. As compared to the existing method of enzymatic labeling, the easy preparation and stability of these labels make them very suitable for PEC amplification. Another merit of this method is that it separates the immunobinding from the PEC transducer, which eliminates the commonly existing affection during the biorecognition processes. This work paves a new route for the PEC immunoassay of HIV-1 p24 antigen and provides a general format for the PEC biomolecular detection by means of the DNA labeling.

  8. Effectiveness of Combining Tangible Symbols with the Picture Exchange Communication System to Teach Requesting Skills to Children with Multiple Disabilities Including Visual Impairment

    ERIC Educational Resources Information Center

    Ali, Emad; MacFarland, Stephanie Z.; Umbreit, John

    2011-01-01

    The Picture Exchange Communication System (PECS) is an augmentative and alternative communication (AAC) program used to teach functional requesting and commenting skills to people with disabilities (Bondy & Frost, 1993; Frost & Bondy, 2002). In this study, tangible symbols were added to PECS in teaching requesting to four students (ages 7-14) with…

  9. The Effectiveness of Combining Tangible Symbols with the Picture Exchange Communication System to Teach Requesting Skills to Children with Multiple Disabilities Including Visual Impairment

    ERIC Educational Resources Information Center

    Ali, Emad

    2009-01-01

    The Picture Exchange Communication System (PECS) is an augmentative and alternative communication program (Frost & Bondy, 2002). Although PECS has been effectively used to teach functional requesting skills for children with autism, mental retardation, visual impairment, and physical disabilities (e.g., Anderson, Moore, & Bourne, 2007; Chambers &…

  10. The Picture Exchange Communication System: Effects on Manding and Speech Development for School-Aged Children with Autism

    ERIC Educational Resources Information Center

    Tincani, Matt; Crozier, Shannon; Alazett, Shannon

    2006-01-01

    We examined the effects of the Picture Exchange Communication System (PECS; Frost & Bondy, 2002) on the manding (requesting) and speech development of school-aged children with autism. In study 1, two participants, Damian and Bob, were taught PECS within a delayed multiple baseline design. Both participants demonstrated increased levels of manding…

  11. An Evaluation of Strategies for Training Staff to Implement the Picture Exchange Communication System

    ERIC Educational Resources Information Center

    Barnes, Clarissa S.; Dunning, Johnna L.; Rehfeldt, Ruth Anne

    2011-01-01

    The picture exchange communication system (PECS) is a functional communication system frequently used with individuals diagnosed with autism spectrum disorders who experience severe language delays (Frost & Bondy, 2002). Few empirical investigations have evaluated strategies for training direct care staff how to effectively implement PECS with…

  12. Materials International Space Station Experiment (MISSE) 5 Developed to Test Advanced Solar Cell Technology Aboard the ISS

    NASA Technical Reports Server (NTRS)

    Wilt, David M.

    2004-01-01

    The testing of new technologies aboard the International Space Station (ISS) is facilitated through the use of a passive experiment container, or PEC, developed at the NASA Langley Research Center. The PEC is an aluminum suitcase approximately 2 ft square and 5 in. thick. Inside the PEC are mounted Materials International Space Station Experiment (MISSE) plates that contain the test articles. The PEC is carried to the ISS aboard the space shuttle or a Russian resupply vehicle, where astronauts attach it to a handrail on the outer surface of the ISS and deploy the PEC, which is to say the suitcase is opened 180 deg. Typically, the PEC is left in this position for approximately 1 year, at which point astronauts close the PEC and it is returned to Earth. In the past, the PECs have contained passive experiments, principally designed to characterize the durability of materials subjected to the ultraviolet radiation and atomic oxygen present at the ISS orbit. The MISSE5 experiment is intended to characterize state-of-art (SOA) and beyond photovoltaic technologies.

  13. EXTRAINTESTINAL PATHOGENIC ESCHERICHIA COLI (EXPEC)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extraintestinal pathogenic Escherichia coli (ExPEC) possess virulence traits that allow them to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgic...

  14. Albumin-induced apoptosis of glomerular parietal epithelial cells is modulated by extracellular signal-regulated kinase 1/2

    PubMed Central

    Ohse, Takamoto; Krofft, Ron D.; Wu, Jimmy S.; Eddy, Allison A.; Pippin, Jeffrey W.; Shankland, Stuart J.

    2012-01-01

    Background. The biological role(s) of glomerular parietal epithelial cells (PECs) is not fully understood in health or disease. Given its location, PECs are constantly exposed to low levels of filtered albumin, which is increased in nephrotic states. We tested the hypothesis that PECs internalize albumin and increased uptake results in apoptosis. Methods. Confocal microscopy of immunofluorescent staining and immunohistochemistry were used to demonstrate albumin internalization in PECs and to quantitate albumin uptake in normal mice and rats as well as experimental models of membranous nephropathy, minimal change disease/focal segmental glomerulosclerosis and protein overload nephropathy. Fluorescence-activated cell sorting analysis was performed on immortalized cultured PECs exposed to fluorescein isothiocyanate (FITC)-labeled albumin in the presence of an endosomal inhibitor or vehicle. Apoptosis was measured by Hoechst staining in cultured PECs exposed to bovine serum albumin. Levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (p-ERK1/2) were restored by retroviral infection of mitogen-activated protein kinase (MEK) 1/2 and reduced by U0126 in PECs exposed to high albumin levels in culture and apoptosis measured by Hoechst staining. Results. PECs internalized albumin normally, and this was markedly increased in all of the experimental disease models (P < 0.05 versus controls). Cultured immortalized PECs also internalize FITC-labeled albumin, which was reduced by endosomal inhibition. A consequence of increased albumin internalization was PEC apoptosis in vitro and in vivo. Candidate signaling pathways underlying these events were examined. Data showed markedly reduced levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (ERK1/2) in PECs exposed to high albumin levels in nephropathy and in culture. A role for ERK1/2 in limiting albumin-induced apoptosis was shown by restoring p-ERK1/2 by retroviral infection, which reduced

  15. MISSE 6-Testing Materials in Space

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S; Kinard, William H.

    2008-01-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment by placing them in space environment for several months. In this paper, a few materials and components from NASA Langley Research Center (LaRC) that have been flown on MISSE 6 mission will be discussed. These include laser and optical elements for photonic devices. The pre-characterized MISSE 6 materials were packed inside a ruggedized Passive Experiment Container (PEC) that resembles a suitcase. The PEC was tested for survivability due to launch conditions. Subsequently, the MISSE 6 PEC was transported by the STS-123 mission to International Space Station (ISS) on March 11, 2008. The astronauts successfully attached the PEC to external handrails and opened the PEC for long term exposure to the space environment.

  16. N,N-Dimethyl chitosan/heparin polyelectrolyte complex vehicle for efficient heparin delivery.

    PubMed

    Bueno, Pedro V A; Souza, Paulo R; Follmann, Heveline D M; Pereira, Antonio G B; Martins, Alessandro F; Rubira, Adley F; Muniz, Edvani C

    2015-04-01

    Polysaccharide-based device for oral delivery of heparin (HP) was successfully prepared. Previously synthesized N,N-dimethyl chitosan (DMC) (86% dimethylated by (1)H NMR spectroscopy) was complexed with HP by mixing HP and DMC aqueous solutions (both at pH 3.0). The polyelectrolyte complex (PEC) obtention was confirmed by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG) and wide-angle X-ray scattering (WAXS). In vitro controlled release assays of HP from PEC were investigated in the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF). The PEC efficiently protected the HP in SGF condition in which HP is degraded. On the other hand, in SIF PEC promoted the releasing of 80 ± 1.5% of loaded HP. The promissory results indicated that the PEC based on DMC/HP presented potential as drug-carrier matrix, since biological activity of HP was improved at pH close to physiological condition.

  17. Modeling and Simulations in Photoelectrochemical Water Oxidation: From Single Level to Multiscale Modeling.

    PubMed

    Zhang, Xueqing; Bieberle-Hütter, Anja

    2016-06-01

    This review summarizes recent developments, challenges, and strategies in the field of modeling and simulations of photoelectrochemical (PEC) water oxidation. We focus on water splitting by metal-oxide semiconductors and discuss topics such as theoretical calculations of light absorption, band gap/band edge, charge transport, and electrochemical reactions at the electrode-electrolyte interface. In particular, we review the mechanisms of the oxygen evolution reaction, strategies to lower overpotential, and computational methods applied to PEC systems with particular focus on multiscale modeling. The current challenges in modeling PEC interfaces and their processes are summarized. At the end, we propose a new multiscale modeling approach to simulate the PEC interface under conditions most similar to those of experiments. This approach will contribute to identifying the limitations at PEC interfaces. Its generic nature allows its application to a number of electrochemical systems.

  18. Photoelectrochemical Carbon Dioxide Reduction Using a Nanoporous Ag Cathode.

    PubMed

    Zhang, Yan; Luc, Wesley; Hutchings, Gregory S; Jiao, Feng

    2016-09-21

    Solar fuel production from abundant sources using photoelectrochemical (PEC) systems is an attractive approach to address the challenges associated with the intermittence of solar energy. In comparison to electrochemical systems, PEC cells directly utilize solar energy as the energy input, and if necessary, then an additional external bias can be applied to drive the desired reaction. In this work, a PEC cell composing of a Ni-coated Si photoanode and a nanoporous Ag cathode was developed for CO2 conversion to CO. The thin Ni layer not only protected the Si wafer from photocorrosion but also served as the oxygen evolution catalyst. At an external bias of 2.0 V, the PEC cell delivered a current density of 10 mA cm(-2) with a CO Faradaic efficiency of ∼70%. More importantly, a stable performance up to 3 h was achieved under photoelectrolysis conditions, which is among the best literature-reported performances for PEC CO2 reduction cells. The photovoltage of the PEC cell was estimated to be ∼0.4 V, which corresponded to a 17% energy saving by solar energy utilization. Postreaction structural analysis showed the corrosion of the Ni layer at the Si photoanode/catalyst interface, which caused performance degradation under prolonged operations. A stable oxygen evolution catalyst with a robust interface is crucial to the long-term stability of PEC CO2 reduction cells. PMID:27588723

  19. Use of zebrafish to probe the divergent virulence potentials and toxin requirements of extraintestinal pathogenic Escherichia coli.

    PubMed

    Wiles, Travis J; Bower, Jean M; Redd, Michael J; Mulvey, Matthew A

    2009-12-01

    Extraintestinal pathogenic E. coli (ExPEC) cause an array of diseases, including sepsis, neonatal meningitis, and urinary tract infections. Many putative virulence factors that might modulate ExPEC pathogenesis have been identified through sequencing efforts, epidemiology, and gene expression profiling, but few of these genes have been assigned clearly defined functional roles during infection. Using zebrafish embryos as surrogate hosts, we have developed a model system with the ability to resolve diverse virulence phenotypes and niche-specific restrictions among closely related ExPEC isolates during either localized or systemic infections. In side-by-side comparisons of prototypic ExPEC isolates, we observed an unexpectedly high degree of phenotypic diversity that is not readily apparent using more traditional animal hosts. In particular, the capacity of different ExPEC isolates to persist and multiply within the zebrafish host and cause disease was shown to be variably dependent upon two secreted toxins, alpha-hemolysin and cytotoxic necrotizing factor. Both of these toxins appear to function primarily in the neutralization of phagocytes, which are recruited in high numbers to sites of infection where they act as an essential host defense against ExPEC as well as less virulent E. coli strains. These results establish zebrafish as a valuable tool for the elucidation and functional analysis of both ExPEC virulence factors and host defense mechanisms.

  20. Dietary zinc and BCG injection influence macrophage function

    SciTech Connect

    Briske-Anderson, M.J.; Kramer, T.R.

    1986-03-05

    Weanling male Lewis rats were fed ad-libitum for 21-25 days a diet based on AIN standards containing 20% egg-white protein and deficient (2 ..mu..g/g) or adequate (20 ..mu..g/g) zinc. A pair-fed (PF) group was fed a Zn-adequate diet, equal to the amount consumed by Zn-deficient rats. Zn-deficient rats exhibited typical signs of Zn deficiency. Seven days prior to completion of dietary regimen rats from each group (N=10) were injected in the forelimb footpads with 250 ..mu..g of BCG (Cell wall skeleton of bacille Calmette Guerin) in Incomplete Freund's Adjuvant (IFA), or with IFA alone. Three days prior to completion of dietary regimen rats from each group were injected intraperitoneally with sterile paraffin oil. Upon completion of dietary regimen peritoneal exudate cells (PEC) were collected. Equivalent phagocytic activity (chemiluminescence) was exhibited by PEC from Zn-deficient and PF rats injected with BCG or IFA, and by PEC from Zn-adequate rats injected with IFA. Phagocytic activity by PEC of BCG injected Zn-adequate rats was significantly higher than in PEC of the other groups. PEC from BCG injected Zn-adequate, Zn-deficient and PF rats, however, equivalently suppressed the proliferation of Con-A stimulated SLC from control (noninjected, Zn-adequate) rats. The findings suggest that PEC of BCG injected Zn-adequate rats produce elevated hydrogen peroxide and hydroxyl radicals.

  1. Use of Zebrafish to Probe the Divergent Virulence Potentials and Toxin Requirements of Extraintestinal Pathogenic Escherichia coli

    PubMed Central

    Wiles, Travis J.; Bower, Jean M.; Redd, Michael J.; Mulvey, Matthew A.

    2009-01-01

    Extraintestinal pathogenic E. coli (ExPEC) cause an array of diseases, including sepsis, neonatal meningitis, and urinary tract infections. Many putative virulence factors that might modulate ExPEC pathogenesis have been identified through sequencing efforts, epidemiology, and gene expression profiling, but few of these genes have been assigned clearly defined functional roles during infection. Using zebrafish embryos as surrogate hosts, we have developed a model system with the ability to resolve diverse virulence phenotypes and niche-specific restrictions among closely related ExPEC isolates during either localized or systemic infections. In side-by-side comparisons of prototypic ExPEC isolates, we observed an unexpectedly high degree of phenotypic diversity that is not readily apparent using more traditional animal hosts. In particular, the capacity of different ExPEC isolates to persist and multiply within the zebrafish host and cause disease was shown to be variably dependent upon two secreted toxins, α-hemolysin and cytotoxic necrotizing factor. Both of these toxins appear to function primarily in the neutralization of phagocytes, which are recruited in high numbers to sites of infection where they act as an essential host defense against ExPEC as well as less virulent E. coli strains. These results establish zebrafish as a valuable tool for the elucidation and functional analysis of both ExPEC virulence factors and host defense mechanisms. PMID:20019794

  2. Drug delivery and cell interaction of adhesive poly(ethyleneimine)/sulfated polysaccharide complex particle films.

    PubMed

    Müller, Martin; Torger, Bernhard; Wehrum, Diana; Vehlow, David; Urban, Birgit; Woltmann, Beatrice; Hempel, Ute

    2015-01-01

    Herein, the authors report and review polyelectrolyte complex (PEC) nanoparticles (NPs) loaded with zoledronate (ZOL) and simvastatin and their effects on bone cells. PEC NPs are intended for modification of bone substitute materials. For characterization, they can be solution casted on germanium (Ge) substrates serving as analytically accessible model substrate. PEC NPs were generated by mixing poly(ethyleneimine) (PEI) either with linear cellulose sulfate (CS) or with branched dextransulfate (DS). Four important requirements for drug loaded PEC NPs and their films are addressed herein, which are the colloidal stability of PEC dispersions (1), interfacial stability (2), cytocompatibility (3), and retarded drug release (4). Dynamic light scattering measurements (DLS) showed that both PEI/CS and PEI/DS PEC NP were obtained with hydrodynamic radii in the range of 35-170 nm and were colloidally stable up to several months. Transmission FTIR spectroscopy evidenced that films of both systems were stable in contact to the release medium up to several days. ZOL-loaded PEI/CS nanoparticles, which were immobilized on an osteoblast-derived extracellular matrix, reduced significantly the resorption and the metabolic activity of human monocyte-derived osteoclasts. FTIR spectroscopy at cast PEC/drug films at Ge substrates revealed retarded drug releases in comparison to the pure drug films.

  3. Poly(L-glutamic acid)/chitosan polyelectrolyte complex porous microspheres as cell microcarriers for cartilage regeneration.

    PubMed

    Fang, Jianjun; Zhang, Yun; Yan, Shifeng; Liu, Zhiwen; He, Shiming; Cui, Lei; Yin, Jingbo

    2014-01-01

    In this study a novel kind of porous poly(l-glutamic acid) (PLGA)/chitosan polyelectrolyte complex (PEC) microsphere was developed through electrostatic interaction between PLGA and chitosan. By adjusting the formula parameters chitosan microspheres with an average pore size of 47.5 ± 5.4 μm were first developed at a concentration of 2 wt.% and freeze temperature of -20 °C. For self-assembly of the PEC microspheres porous chitosan microspheres were then incubated in PLGA solution at 37 °C. Due to electrostatic interaction a large amount of PLGA (110.3 μg mg(-1)) was homogeneously absorbed within the chitosan microspheres. The developed PEC microspheres retained their original size, pore diameters and interconnected porous structure. Fourier transform infrared spectroscopy, thermal gravimetric analysis and zeta potential analysis revealed that the PEC microspheres were successfully prepared through electrostatic interaction. Compared with microspheres fabricated from chitosan, the porous PEC microspheres were shown to efficiently promote chondrocyte attachment and proliferation. After injection subcutaneously for 8 weeks PEC microspheres loaded with chondrocytes were found to produce significant more cartilaginous matrix than chitosan microspheres. These results indicate that these novel fabricated porous PLGA/chitosan PEC microspheres could be used as injectable cell carriers for cartilage tissue engineering. PMID:24025620

  4. Electricity generation and pollutant degradation using a novel biocathode coupled photoelectrochemical cell.

    PubMed

    Du, Yue; Feng, Yujie; Qu, Youpeng; Liu, Jia; Ren, Nanqi; Liu, Hong

    2014-07-01

    The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst. PMID:24863439

  5. Thickness Evaluation of Aluminium Plate Using Pulsed Eddy Current Technique

    NASA Astrophysics Data System (ADS)

    Singh, Gurpartap; Bapat, Harsh Madhukar; Singh, Bhanu Pratap; Bandyopadhyay, Manojit; Puri, Rakesh Kumar; Badodkar, Deepak Narayanrao

    2013-10-01

    This paper describes a pulsed eddy current (PEC) based non-destructive testing system used for detection of thickness variation in aluminium plate. A giant magneto-resistive sensor has been used instead of pick up coil for detecting resultant magnetic field. The PEC response signals obtained from 1 to 5 mm thickness change in aluminium plate were investigated. Two time domain features, namely peak value and time to peak, of PEC response were used for extracting information about thickness variation in aluminium plate. The variation of peak value and time to peak with thickness was compared. A program was developed to display the thickness variation of the tested sample.

  6. Photoelectrochemical bioanalysis: the state of the art.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2015-02-01

    The evolution of photoelectrochemical (PEC) bioanalysis has resulted in substantial progress in its analytical performance and biodetection applications. The aim of this review is to provide a panoramic snapshot of the state of the art in this dynamically developing field, with special emphasis on PEC DNA analysis, immunoassay, enzymatic biosensing and cell-related detection. The future prospects in this area are also evaluated and discussed. This work will serve as a useful source to inform the interested audience of the latest developments and applications in the field of PEC bioanalysis. PMID:25223761

  7. A study of potential energy curves from the model space quantum Monte Carlo method

    SciTech Connect

    Ohtsuka, Yuhki; Ten-no, Seiichiro

    2015-12-07

    We report on the first application of the model space quantum Monte Carlo (MSQMC) to potential energy curves (PECs) for the excited states of C{sub 2}, N{sub 2}, and O{sub 2} to validate the applicability of the method. A parallel MSQMC code is implemented with the initiator approximation to enable efficient sampling. The PECs of MSQMC for various excited and ionized states are compared with those from the Rydberg-Klein-Rees and full configuration interaction methods. The results indicate the usefulness of MSQMC for precise PECs in a wide range obviating problems concerning quasi-degeneracy.

  8. PULSED EDDY CURRENT THICKNESS MEASUREMENT OF SELECTIVE PHASE CORROSION ON NICKEL ALUMINUM BRONZE VALVES

    SciTech Connect

    Krause, T. W.; Harlley, D.; Babbar, V. K.; Wannamaker, K.

    2010-02-22

    Nickel Aluminum Bronze (NAB) is a material with marine environment applications that under certain conditions can undergo selective phase corrosion (SPC). SPC involves the removal of minority elements while leaving behind a copper matrix. Pulsed eddy current (PEC) was evaluated for determination of SPC thickness on a NAB valve section with access from the surface corroded side. A primarily linear response of PEC amplitude, up to the maximum available SPC thickness of 4 mm was observed. The combination of reduced conductivity and permeability in the SPC phase relative to the base NAB was used to explain the observed sensitivity of PEC to SPC thickness variations.

  9. Electricity generation and pollutant degradation using a novel biocathode coupled photoelectrochemical cell.

    PubMed

    Du, Yue; Feng, Yujie; Qu, Youpeng; Liu, Jia; Ren, Nanqi; Liu, Hong

    2014-07-01

    The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst.

  10. Characterization of extraintestinal pathogenic Escherichia coli isolated from captive wild felids with bacteremia.

    PubMed

    Carvalho, Vania M; Osugui, Lika; Setzer, Ariela P; Lopez, Rodrigo P G; Pestana de Castro, Antonio F; Irino, Kinue; Catão-Dias, José L

    2012-09-01

    Diseases caused by extraintestinal pathogenic Escherichia coli (ExPEC) in wild felids are rarely reported. Although urinary tract infections are infrequently reported in domestic cats, such infections when present are commonly caused by ExPEC. The present work characterized ExPEC strains isolated from 2 adult felines, a snow leopard (Panthera uncia) and a black leopard (Panthera pardus melas), that died from secondary bacteremia associated with urinary tract infections. Isolates from both animals were classified into the B2 phylogenetic group and expressed virulence genotypes that allowed them to cause severe disease. In addition, strains from the black leopard showed multidrug resistance.

  11. Design and engineering of disulfide crosslinked nanocomplexes of polyamide polyelectrolytes: stability under biorelevant conditions and potent cellular internalization of entrapped model peptide.

    PubMed

    Sharma, Aashish; Kundu, Somanath; Reddy M, Amarendar; Bajaj, Avinash; Srivastava, Aasheesh

    2013-07-01

    Counter polyelectrolytes (PEs) having a degradable polyamide backbone and controlled thiolation are prepared. Their nanosized polyelectrolyte complexes (PECs) spontaneously crosslink under ambient conditions via bioreducible disulfide bonds. These PECs are regenerable after centrifugation, and resist degradation by proteases. They are stable to variations of pH and electrolyte concentration, similar to those encountered in biological milieu. However, they are unraveled in reductive conditions. These PECs act as efficient vectors for delivering entrapped cargo. They entrap with high efficiency, and controllably release, fluorescein isothiocyanate (FITC)-insulin (a model peptide) in vitro. Potent cellular internalization of FITC-insulin within human lung cancer cells with high cell viability is demonstrated.

  12. Characterization of extraintestinal pathogenic Escherichia coli isolated from captive wild felids with bacteremia.

    PubMed

    Carvalho, Vania M; Osugui, Lika; Setzer, Ariela P; Lopez, Rodrigo P G; Pestana de Castro, Antonio F; Irino, Kinue; Catão-Dias, José L

    2012-09-01

    Diseases caused by extraintestinal pathogenic Escherichia coli (ExPEC) in wild felids are rarely reported. Although urinary tract infections are infrequently reported in domestic cats, such infections when present are commonly caused by ExPEC. The present work characterized ExPEC strains isolated from 2 adult felines, a snow leopard (Panthera uncia) and a black leopard (Panthera pardus melas), that died from secondary bacteremia associated with urinary tract infections. Isolates from both animals were classified into the B2 phylogenetic group and expressed virulence genotypes that allowed them to cause severe disease. In addition, strains from the black leopard showed multidrug resistance. PMID:22826042

  13. High-performance photoelectrochemical cells based on a binuclear ruthenium catalyst for visible-light-driven water oxidation.

    PubMed

    Zhang, Linlin; Gao, Yan; Ding, Xin; Yu, Ze; Sun, Licheng

    2014-10-01

    Two photoanodes based on a binuclear (2) and a mononuclear ruthenium (3) water oxidation catalysts were assembled in combination with a molecular photosensitizer (1) by using a co-adsorption method. The anodes were used in dye-sensitized photoelectrochemical cells (DS-PECs) for visible-light-driven water splitting. A DS-PEC device using TiO2 (1+2) as working electrode (WE) exhibits better performance than TiO2 (1+3) as WE in light-driven water splitting. Detailed photoelectrochemical studies on these DS-PEC devices are discussed. PMID:25139154

  14. [Quality control in anesthesiology. Results of a prospective study following the recommendations of the German Society of Anesthesiology and Intensive Care].

    PubMed

    Schwilk, B; Muche, R; Bothner, U; Goertz, A; Friesdorf, W; Georgieff, M

    1995-04-01

    The German Social Law has required quality assurance (QA) procedures since 1989. The measures must be suitable to allow "comparing investigations". In 1992 the German Society of Anaesthesiology and Intensive Care Medicine published recommendations for QA in anaesthesia: most problems during an anaesthetic should be documented in a standardised manner, and thus, a list of 63 pitfalls, events, and complications (PECs) and five degrees of severity were defined. The goal of this study was to determine the frequency of PECs in anaesthesia and to correlate PECs with procedures and preoperative health status. MATERIALS AND METHODS. Demographic data, preoperative findings, type and duration of anaesthesia and operation, and kind and severity of PECs were integrated in an automatically readable anaesthetic data record (ARADR). During 12 months all anaesthetics in our department were documented by the ARADR; the records were read by a reading device and the data stored in a modern SQL database (Informix). Degrees of severity: I. PEC leads to reaction of anaesthetist, no impact for recovery room (RR); II. impact for RR, no impact on transfer to ward; III. significant prolongation of RR stay or additional monitoring on ward; IV. PEC leads to intensive care unit admission; V. disabling damage or death. RESULTS. In all, 18350 anaesthetics were recorded (9055 male, 9295 female); the median age was 41 years (1 day-99 years). In 4251 (23.2%) anaesthetics 5927 PECs occurred, 3412 of them involving the cardiovascular and 949 the respiratory system, the latter with a tendency to higher degrees of severity. PECs caused by technical equipment (126) or lesions caused by anaesthesists (342) had no fatal outcomes and were less severe. Patients in ASA class I had 12.3% anaesthetics with PECs, ASA II 23.3%, ASA III 33.8%, ASA IV 34.9%, and ASA V 58.5%. PECs of degrees IV and V showed a higher incidence in the higher ASA classes. There was no fatal PEC in an ASA class I patient and only one

  15. Using an adapted form of the picture exchange communication system to increase independent requesting in deafblind adults with learning disabilities.

    PubMed

    Bracken, Maeve; Rohrer, Nicole

    2014-02-01

    The current study assessed the effectiveness of an adapted form of the Picture Exchange Communication System (PECS) in increasing independent requesting in deafblind adults with learning disabilities. PECS cards were created to accommodate individual needs, including adaptations such as enlarging photographs and using swelled images which consisted of images created on raised line drawing paper. Training included up to Phase III of PECS and procedures ensuring generalizations across individuals and contexts were included. The effects of the intervention were evaluated using a multiple baseline design across participants. Results demonstrated an increase in independent requesting with each of the participants reaching mastery criterion. These results suggest that PECS, in combination with some minor adaptations, may be an effective communicative alternative for individuals who are deafblind and have learning impairments. PMID:24316491

  16. Extensive theoretical studies on the low-lying electronic states of BBr+

    NASA Astrophysics Data System (ADS)

    Niu, Xianghong; Shu, Huabing; Zhu, Zunlue; Chen, Qian

    2016-04-01

    The potential energy curves (PECs) of two lowest dissociation channels of BBr+ have been thoroughly investigated using the internally contracted multireference configuration interaction method with Davidson correction and relativistic correction. All PECs are extrapolated to complete basis set limit. Several quasibound excited states caused by avoided crossings are found. Based on the PECs, the spectroscopic parameters of bound and quasibound states are obtained. The transition dipole moments and radiative lifetimes are predicted for all possible transitions. Finally, the spin-orbit coupling matrix elements are computed using the states interaction approach with the full Breit-Pauli Hamiltonian to analyze the interactions in PECs crossing regions. We propose that the 22Σ+-X2Σ+ and 22Π-X2Σ+ transitions which cannot be observed in experiments are attributed to the intricate couplings among 12Π, 22Π, 22Σ+, 14Σ+, 14Δ, 14Σ-, 12Δ and 12Σ- states.

  17. Photoelectrocatalytic hydrogen generation and simultaneous degradation of organic pollutant via CdSe/TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Wang, Wenchao; Li, Fang; Zhang, Dieqing; Leung, Dennis Y. C.; Li, Guisheng

    2016-01-01

    CdSe nanoparticles enhanced TiO2 nanotube arrays electrodes (CdSe/TNTAs) were explored as the photoanode for driving the photoelectrocatalytic (PEC) generation of hydrogen and simultaneous degradation of organic pollutants in a PEC system. The evolution hydrogen and the simultaneous degradation of organic pollutants were performed in an electrolytic cell (three electrodes system) under visible-light (λ > 400 nm). Such CdSe/TiO2 based PEC system exhibited both high efficiency of hydrogen generation and effective oxidation of methyl orange (MO). Such high PEC performance of CdSe/TNTAs was attributed to the high dispersity of CdSe nanoparticles on both outside and inside of the pore walls of TiO2 nanotube arrays, the strong combination and heterojunctions between CdSe and TiO2 through Cdsbnd O bonds via electrodeposition with ion-exchange method.

  18. Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.

    PubMed

    Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

    2014-11-26

    The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains.

  19. Optical materials technology for energy efficiency and solar energy conversion XI: Photovoltaics, photochemistry, and photoelectrochemistry; Proceedings of the Meeting, Toulouse, France, May 19, 21, 1992

    NASA Astrophysics Data System (ADS)

    Hugot-Le Goff, Anne; Granqvist, Claes-Goran; Lampert, Carl M.

    1992-12-01

    The present conference on solar photovoltaic (PV) and photoelectrochemical (PEC) devices discusses charge-carrier photogeneration in organic solar cells, the kinetics of charge-transfer reactions in PEC solar cells, PV devices from II-VI films, the defect pool-gap state distribution in amorphous-Si:H in equilibrium and under photoexcitation, and the second phases in CdS/CuInSe2 solar cells. Also treated are MOCVD of FeS for solar energy conversion, nanostructured TiO2 films, the optical properties of pyrite thin films annealed at different temperatures, the surface modification of CuGaSe2 thin films via PEC methods, organic and inorganic materials for PV and PEC devices, and the synthesis and testing of organic semiconductor solar cells. (No individual items are abstracted in this volume)

  20. Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.

    PubMed

    Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

    2014-11-26

    The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. PMID:25256478

  1. Supercritical fluid extraction (SFE) of cranberries does not extract oligomeric proanthocyanidins (PAC) but does alter the chromatography and bioactivity of PAC fractions extracted from SFE residues.

    PubMed

    Feliciano, Rodrigo P; Meudt, Jennifer J; Shanmuganayagam, Dhanansayan; Metzger, Brandon T; Krueger, Christian G; Reed, Jess D

    2014-08-01

    Supercritical fluid extraction (SFE) removed lipophilic compounds and low molecular weight flavonoids from cranberries. However, SFE did not extract proanthocyanidins (PAC). The SFE PAC-enriched residue was submitted to fractionation on Sephadex LH-20 using ethanol, ethanol/methanol, and 80% acetone. PAC degree of polymerization (DP) and ratios of "A-type" to "B-type" interflavan bonds were compared with those of PAC fractions without SFE. Mass spectrometry showed that when SFE was used, PAC distribution was shifted toward higher DP and contained higher amounts of two and three "A-type" bonds compared to PAC fractions without SFE. The 80% acetone fraction with SFE had significantly greater extraintestinal pathogenic Escherichia coli (ExPEC) agglutination and significantly lower ExPEC invasion of enterocytes than the fraction without SFE. Cranberry PAC with higher numbers of "A-type" interflavan bonds are more bioactive in agglutinating ExPEC and inhibiting ExPEC enterocyte invasion.

  2. 77 FR 58587 - Mr. James Chaisson; Confirmatory Order (Effective Immediately)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ..., arranged through Cornell University's Institute on Conflict Resolution. This Confirmatory Order is issued... Confirmatory Order is the result of an agreement reached during an alternative dispute resolution (ADR... opportunity to request a predecisional enforcement conference (PEC), or request alternative dispute...

  3. Electrochemically reduced graphene oxide on silicon nanowire arrays for enhanced photoelectrochemical hydrogen evolution.

    PubMed

    Meng, Huan; Fan, Ke; Low, Jingxiang; Yu, Jiaguo

    2016-09-21

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen by sunlight is a promising approach to solve energy and environmental problems. In this work, silicon nanowire arrays (SiNWs) photocathodes decorated with reduced graphene oxide (rGO) for PEC water splitting were successfully prepared by a flexible and scalable electrochemical reduction method. The SiNWs photocathode with the optimized rGO decoration (SiNWs/rGO20) shows an enhanced activity with a much higher photocurrent density and significantly positive shift of onset potential compared to the bare SiNWs arrays for the hydrogen evolution reaction (HER). The enhanced PEC activity is ascribed to the high electrical conductivity of rGO and improved separation of the photogenerated charge carriers. This work not only demonstrates a facile, rapid and tunable electrochemical reduction method to produce rGO, but also exhibits an efficient protocol to enhance the PEC water splitting of silicon-based materials. PMID:27461187

  4. Comparative virulence of urinary and bloodstream isolates of extra-intestinal pathogenic Escherichia coli in a Galleria mellonella model.

    PubMed

    Ciesielczuk, Holly; Betts, Jonathon; Phee, Lynnette; Doumith, Michel; Hope, Russell; Woodford, Neil; Wareham, David W

    2015-01-01

    Extra-intestinal pathogenic Escherichia coli (ExPEC) are a significant cause of urinary tract infections and bacteraemia worldwide. Currently no single virulence factor or ExPEC lineage has been identified as the sole contributor to severe extra-intestinal infection and/or urosepsis. Galleria mellonella has recently been established as a simple model for studying the comparative virulence of ExPEC. In this study we investigated the virulence of 40 well-characterized ExPEC strains, in G. mellonella, by measuring mortality (larvae survival), immune recognition/response (melanin production) and cell damage (lactate dehydrogenase production). Although mortality was similar between urinary and bloodstream isolates, it was heightened for community-associated infections, complicated UTIs and urinary-source bacteraemia. Isolates of ST131 and those possessing afa/dra, ompT and serogroup O6 were also associated with heightened virulence. PMID:25853733

  5. Photoelectrochemical hydrogen production from biomass derivatives and water.

    PubMed

    Lu, Xihong; Xie, Shilei; Yang, Hao; Tong, Yexiang; Ji, Hongbing

    2014-11-21

    Hydrogen, a clean energy carrier with high energy capacity, is a very promising candidate as a primary energy source for the future. Photoelectrochemical (PEC) hydrogen production from renewable biomass derivatives and water is one of the most promising approaches to producing green chemical fuel. Compared to water splitting, hydrogen production from renewable biomass derivatives and water through a PEC process is more efficient from the viewpoint of thermodynamics. Additionally, the carbon dioxide formed can be re-transformed into carbohydrates via photosynthesis in plants. In this review, we focus on the development of photoanodes and systems for PEC hydrogen production from water and renewable biomass derivatives, such as methanol, ethanol, glycerol and sugars. We also discuss the future challenges and opportunities for the design of the state-of-the-art photoanodes and PEC systems for hydrogen production from biomass derivatives and water.

  6. Electrochemically reduced graphene oxide on silicon nanowire arrays for enhanced photoelectrochemical hydrogen evolution.

    PubMed

    Meng, Huan; Fan, Ke; Low, Jingxiang; Yu, Jiaguo

    2016-09-21

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen by sunlight is a promising approach to solve energy and environmental problems. In this work, silicon nanowire arrays (SiNWs) photocathodes decorated with reduced graphene oxide (rGO) for PEC water splitting were successfully prepared by a flexible and scalable electrochemical reduction method. The SiNWs photocathode with the optimized rGO decoration (SiNWs/rGO20) shows an enhanced activity with a much higher photocurrent density and significantly positive shift of onset potential compared to the bare SiNWs arrays for the hydrogen evolution reaction (HER). The enhanced PEC activity is ascribed to the high electrical conductivity of rGO and improved separation of the photogenerated charge carriers. This work not only demonstrates a facile, rapid and tunable electrochemical reduction method to produce rGO, but also exhibits an efficient protocol to enhance the PEC water splitting of silicon-based materials.

  7. Magnetic line source diffraction by a perfect electromagnetic conductor (PEMC) step

    NASA Astrophysics Data System (ADS)

    Ahmed, Saeed

    2015-02-01

    In this paper, an analytic theory for the magnetic line source diffraction by a perfect electromagnetic conductor (PEMC) step is developed. Using the duality transformation, introduced by Lindell and Sihvola, transformations have been made from the diffraction of a magnetic line source by a perfect electric conductor (PEC) step. As an application, plane wave diffracted from a planar interface of air and PEMC media is studied. PEC and PMC are the limiting cases, while there is no cross-polarized component.

  8. Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible-Light Photoelectrochemical Hydrogen Evolution.

    PubMed

    Zheng, Xue-Li; Song, Ji-Peng; Ling, Tao; Hu, Zhen Peng; Yin, Peng-Fei; Davey, Kenneth; Du, Xi-Wen; Qiao, Shi-Zhang

    2016-06-01

    Strongly coupled Nafion molecules and ordered porous CdS networks are fabricated for visible-light photoelectrochemical (PEC) hydrogen evolution. The Nafion layer coating shifts the band position of CdS upward and accelerates charge transfer in the photoelectrode/electrolyte interface. It is highly expected that the strong coupling effect between organic and inorganic materials will provide new routes to advance PEC water splitting. PMID:27038367

  9. Effects of passing electric current on structural relaxation, crystallization and elastic property in amorphous Cu{sub 50}Ti{sub 50}

    SciTech Connect

    Takemoto, R.; Mizubayashi, H.

    1995-04-01

    For amorphous Cu{sub 50}Ti{sub 50}, the authors investigated the effects of passing electric d.c.-current (PEC) other than joule heating on Young`s modulus M below 300 K, the structural relaxation (SR) at {approximately}500 K and the crystallization at {approximately}650 K for the current density i{sub d} below 5 {times} 10{sup 3} A/cm{sup 2}. Under PEC, M shows an increase with increasing i{sub d}, which is reversible for changing i{sub d} and shows no temperature dependence. All the features of the effects of PEC on M are very similar to those reported for the effects of applied strain {var_epsilon}{sub t} on M, when the effects of PEC are assumed to be identical to those of {var_epsilon}{sub t}. On the basis of the scaling found between i{sub d} and {var_epsilon}{sub t}, the authors estimated the apparent effective charge a-Z*e (e = the elementary charge) measuring the electromigration force as 7 {times} 10{sup 4}e, which is the order of 10{sup 4} times larger than the values reported in crystalline metals and alloys. SR is accelerated under PEC for i{sub d} > 2.5 {times} 10{sup 3} A/cm{sup 2}, where the pre-exponential frequency-factor {nu}{sub SR.O} and the activation energy E{sub SR} show a strong increase and a small increase, respectively. For the crystallization, its early stage is accelerated under PEC when the crystallization proceeds rapidly at higher temperatures. This is found to reflect the acceleration of the homogeneous nucleation under PEC. These features found for the effects of PEC are very similar to those reported for various a-alloys, suggesting that they reflect the common characteristics in a-alloys.

  10. Genome Sequence of Avian Escherichia coli Strain IHIT25637, an Extraintestinal Pathogenic E. coli Strain of ST131 Encoding Colistin Resistance Determinant MCR-1

    PubMed Central

    Göttig, Stephan; Bülte, Maria; Fiedler, Sophie; Tietgen, Manuela; Leidner, Ursula; Heydel, Carsten; Bauerfeind, Rolf; Semmler, Torsten

    2016-01-01

    Sequence type 131 (ST131) is one of the predominant Escherichia coli lineages among extraintestinal pathogenic E. coli (ExPEC) that causes a variety of diseases in humans and animals and frequently shows multidrug resistance. Here, we report the first genome sequence of an ST131-ExPEC strain from poultry carrying the plasmid-encoded colistin resistance gene mcr-1. PMID:27587807

  11. Novel porous scaffolds of pH responsive chitosan/carrageenan-based polyelectrolyte complexes for tissue engineering.

    PubMed

    Araujo, J V; Davidenko, N; Danner, M; Cameron, R E; Best, S M

    2014-12-01

    Polyelectrolyte complexes (PECs) represent promising materials for drug delivery and tissue engineering applications. These substances are obtained in aqueous medium without the need for crosslinking agents. PECs can be produced through the combination of oppositely charged medical grade polymers, which include the stimuli responsive ones. In this work, three-dimensional porous scaffolds were produced through the lyophilization of pH sensitive PECs made of chitosan (CS) and carrageenan (CRG). CS:CRG molar ratios of 1:1 (CSCRG1), 2:1 (CSCRG2), and 3:1 (CSCRG3) were used. The chemical compositions of the PECs, as well as their influence in the final structure of the scaffolds were meticulously studied. In addition, the pH responsiveness of the PECs in a range including the physiological pH values of 7.4 (simulating normal physiological conditions) and 4.5 (simulating inflammatory response) was assessed. Results showed that the PECs produced were stable at pH values of 7.4 and under but dissolved as the pH increased to nonphysiological values of 9 and 11. However, after dissolution, the PEC could be reprecipitated by decreasing the pH to values close to 4.5. The scaffolds obtained presented large and interconnected pores, being equally sensitive to changes in the pH. CSCRG1 scaffolds appeared to have higher hydrophilicity and therefore higher water absorption capacity. The increase in the CS:CRG molar ratios improved the scaffold mechanical properties, with CSCRG3 presenting the higher compressive modulus under wet conditions. Overall, the PEC scaffolds appear promising for tissue engineering related applications that require the use of pH responsive materials stable at physiological conditions.

  12. Impaired interleukin 1 production by rat leukocytes during iron deficiency

    SciTech Connect

    Helyar, L.; Sherman, A.R.

    1986-03-05

    Because specific leukocyte functions and protein synthesis in general are impaired in iron deficiency, the production of interleukin 1 (IL-1) by peritoneal exudate cells (PEC) was examined in iron-deficient and control rats. Three groups of weanling male SD rats (n=19-22) were fed a semi-purified diet containing 6, 12, or 35 ppm iron in order to produce severe iron deficiency (SID), moderate iron deficiency (MID), or adequate iron status (AIS). Animals were killed at 42-47 d of age and acute PEC harvested. Crude IL-1 samples were prepared from these PEC, and assayed for activity by in vitro and in vivo methods. IL-1 preparations from SID and MID rats enhanced mouse thymocyte proliferation in vitro less than half as much as IL-1 preparations from AIS rats (p = 0.01). In a rabbit bioassay, injection of IL-1 prepared with 1 x 10/sup 7/ PEC from either SID or MID rats resulted in virtually no change in maximum body temperature. In contrast, IL-1 from AIS source PEC produced a marked change in maximum body temperature of approximately 0.5 F, which was significantly different from the other two groups (p < 0.01). IL-1 preparations from SID or MID source PEC decreased rabbit plasma iron and zinc only one-third to one-eight as much as IL-1 from AIS source PEC (p less than or equal to 0.01). Severe or moderate iron deficiency clearly impairs IL-1 production by rat PEC. This may be another mechanism by which this nutritional deficiency alters the immune inflammatory response.

  13. Self-Enhanced Ultrasensitive Photoelectrochemical Biosensor Based on Nanocapsule Packaging Both Donor-Acceptor-Type Photoactive Material and Its Sensitizer.

    PubMed

    Zheng, Ying-Ning; Liang, Wen-Bin; Xiong, Cheng-Yi; Yuan, Ya-Li; Chai, Ya-Qin; Yuan, Ruo

    2016-09-01

    In this work, a self-enhanced ultrasensitive photoelectrochemical (PEC) biosensor was established based on a functionalized nanocapsule packaging both donor-acceptor-type photoactive material and its sensitizer. The functionalized nanocapsule with self-enhanced PEC responses was achieved first by packaging both the donor-acceptor-type photoactive material (poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}, PTB7-Th) and its sensitizer (nano-C60, fullerene) in poly(ethylene glycol) (PEG) to form a nanocapsule, which significantly enhanced PEC signal and stability of the PEC biosensor. Moreover, a quadratic enzymes-assisted target recycling amplification strategy was introduced to the system for ultrasensitive determination. Compared with other established PEC biosensors, our proposed self-enhanced approach showed higher effectivity, accuracy, sensitivity, and convenience without any addition of coreactant or sensitizers into the testing electrolyte for photocurrent amplification and performed excellent analytical properties for microRNA estimation down to femtomole level with microRNA-141 as a model. Additionally, the proposed PEC biosensor was employed for estimation of microRNA in different cancer cells and pharmacodynamic evaluation in cancer cells. This self-enhanced PEC strategy has laid the foundation for fabrication of simple, effective, and ultrasensitive PEC diagnostic devices, leading to the possibility for early diagnosis, timely stage estimation, and accurate prognosis judgment of disease. PMID:27513736

  14. Self-Enhanced Ultrasensitive Photoelectrochemical Biosensor Based on Nanocapsule Packaging Both Donor-Acceptor-Type Photoactive Material and Its Sensitizer.

    PubMed

    Zheng, Ying-Ning; Liang, Wen-Bin; Xiong, Cheng-Yi; Yuan, Ya-Li; Chai, Ya-Qin; Yuan, Ruo

    2016-09-01

    In this work, a self-enhanced ultrasensitive photoelectrochemical (PEC) biosensor was established based on a functionalized nanocapsule packaging both donor-acceptor-type photoactive material and its sensitizer. The functionalized nanocapsule with self-enhanced PEC responses was achieved first by packaging both the donor-acceptor-type photoactive material (poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}, PTB7-Th) and its sensitizer (nano-C60, fullerene) in poly(ethylene glycol) (PEG) to form a nanocapsule, which significantly enhanced PEC signal and stability of the PEC biosensor. Moreover, a quadratic enzymes-assisted target recycling amplification strategy was introduced to the system for ultrasensitive determination. Compared with other established PEC biosensors, our proposed self-enhanced approach showed higher effectivity, accuracy, sensitivity, and convenience without any addition of coreactant or sensitizers into the testing electrolyte for photocurrent amplification and performed excellent analytical properties for microRNA estimation down to femtomole level with microRNA-141 as a model. Additionally, the proposed PEC biosensor was employed for estimation of microRNA in different cancer cells and pharmacodynamic evaluation in cancer cells. This self-enhanced PEC strategy has laid the foundation for fabrication of simple, effective, and ultrasensitive PEC diagnostic devices, leading to the possibility for early diagnosis, timely stage estimation, and accurate prognosis judgment of disease.

  15. Genome Sequence of Avian Escherichia coli Strain IHIT25637, an Extraintestinal Pathogenic E. coli Strain of ST131 Encoding Colistin Resistance Determinant MCR-1.

    PubMed

    Ewers, Christa; Göttig, Stephan; Bülte, Maria; Fiedler, Sophie; Tietgen, Manuela; Leidner, Ursula; Heydel, Carsten; Bauerfeind, Rolf; Semmler, Torsten

    2016-01-01

    Sequence type 131 (ST131) is one of the predominant Escherichia coli lineages among extraintestinal pathogenic E. coli (ExPEC) that causes a variety of diseases in humans and animals and frequently shows multidrug resistance. Here, we report the first genome sequence of an ST131-ExPEC strain from poultry carrying the plasmid-encoded colistin resistance gene mcr-1. PMID:27587807

  16. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    DOEpatents

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  17. Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible-Light Photoelectrochemical Hydrogen Evolution.

    PubMed

    Zheng, Xue-Li; Song, Ji-Peng; Ling, Tao; Hu, Zhen Peng; Yin, Peng-Fei; Davey, Kenneth; Du, Xi-Wen; Qiao, Shi-Zhang

    2016-06-01

    Strongly coupled Nafion molecules and ordered porous CdS networks are fabricated for visible-light photoelectrochemical (PEC) hydrogen evolution. The Nafion layer coating shifts the band position of CdS upward and accelerates charge transfer in the photoelectrode/electrolyte interface. It is highly expected that the strong coupling effect between organic and inorganic materials will provide new routes to advance PEC water splitting.

  18. Augmentation of metastasis formation by thioglycollate-elicited macrophages.

    PubMed

    Gorelik, E; Wiltrout, R H; Brunda, M J; Holden, H T; Herberman, R B

    1982-05-15

    Inoculation of thioglycollate-elicited peritoneal exudate cells (PEC) into C57BL/6 mice reduced the rate of lung clearance of several intravenously (i.v.) injected murine tumor cells, and increased by up to 100-fold the number of artificially-induced metastatic lung nodules produced by the i.v. injection of B16 melanoma or Lewis lung carcinoma (3LL) tumor cells. Maximum effects were observed when PEC were injected either before, or shortly after, tumor cells. Modulation of lung clearance or metastasis formation was observed only with PEC and not with a variety of other cells, such as splenocytes, thymocytes P815 mastocytoma cells, or several macrophage-like cell lines (PU5-1.8 and IC-21). Lysates of PEC were as efficient in reducing lung clearance and augmenting metastasis formation as were intact viable PEC. Lysates of other cell types, including P815 and the macrophage-like cell lines, were unable to produce these effects. PEC populations, enriched for macrophages by adherence to plastic or by percoll density gradient sedimentation, also increased the number of B16-induced artificial metastasis, implicating the macrophage as the cell responsible for these observations. PMID:7095902

  19. Microscopic endometrial perivascular epithelioid cell nodules: a case report with the earliest presentation of a uterine perivascular epithelioid cell tumor.

    PubMed

    Fang, Chia-Lang; Lin, Yun-Ho; Chen, Wei-Yu

    2012-09-03

    Perivascular epithelioid cell (PEC) tumors (PEComas) are a family of related mesenchymal tumors composed of PECs which co-express melanocytic and smooth muscle markers. Although their distinctive histologic, immunohistochemical, ultrastructural, and genetic features have been clearly demonstrated, their histogenesis and normal counterpart remain largely unknown. Precursor lesions of PEComas have rarely been reported. We herein describe a tuberous sclerosis patient with microscopic PEC nodules in the endometrium of adenomyosis, pelvic endometriosis, an ovarian endometriotic cyst, and the endometrium of the uterine cavity. The nodules showed a mixture of spindle-shaped and epithelioid cells concentrically arranged around small arteries. The cells exhibited uniform nuclei, light eosinophilic cytoplasm, and immunoreactivity with HMB-45 and CD10. Some nodules revealed continuity with a PEComa in the myometrium. These findings support microscopic endometrial PEC nodules possibly being precursor lesions of uterine PEComas. The wide distribution of the nodules in the pelvis may be related to the multicentricity of PEComas in tuberous sclerosis patients. Owing to the immunoreactivity with CD10, microscopic endometrial PEC nodules may be misinterpreted as endothelial stromal cells unless melanocytic markers are stained. To the best of our knowledge, this is a case with the earliest manifestation of PEC lesions occurring in the endometrium. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9658280017862643.

  20. Cationic and anionic polyelectrolyte complexes of xylan and chitosan. Interaction with lignocellulosic surfaces.

    PubMed

    Mocchiutti, Paulina; Schnell, Carla N; Rossi, Gerardo D; Peresin, María S; Zanuttini, Miguel A; Galván, María V

    2016-10-01

    Cationic (CatPECs) and anionic (AnPECs) polyelectrolyte complexes from xylan and chitosan were formed, characterized and adsorbed onto unbleached fibers for improving the papermaking properties. They were prepared at a level of 30% of neutralization charge ratio by modifying the order of addition of polyelectrolytes and the ionic strength (0.01N and 0.1N NaCl). The charge density, colloidal stability and particle size of polyelectrolyte complexes (PECs) was measured using polyelectrolyte titration method, Turbiscan and Zetasizer Nano equipments, respectively. All the complexes were stable even after seven days from PEC formation. DRIFT spectra of complexes were also analyzed. The adsorption behavior of them onto cellulose nanofibrils model surfaces was studied using quartz crystal microbalance with dissipation monitoring, and surface plasmon resonance. It was found that the PEC layers were viscoelastic and highly hydrated. Finally, it is shown that the adsorbed PECs onto cellulosic fibers markedly improved the tensile and crushing strengths of paper. PMID:27312617

  1. Engineering MoSx/Ti/InP Hybrid Photocathode for Improved Solar Hydrogen Production

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Zheng, Maojun; Zhong, Miao; Ma, Liguo; Wang, Faze; Ma, Li; Shen, Wenzhong

    2016-07-01

    Due to its direct band gap of ~1.35 eV, appropriate energy band-edge positions, and low surface-recombination velocity, p-type InP has attracted considerable attention as a promising photocathode material for solar hydrogen generation. However, challenges remain with p-type InP for achieving high and stable photoelectrochemical (PEC) performances. Here, we demonstrate that surface modifications of InP photocathodes with Ti thin layers and amorphous MoSx nanoparticles can remarkably improve their PEC performances. A high photocurrent density with an improved PEC onset potential is obtained. Electrochemical impedance analyses reveal that the largely improved PEC performance of MoSx/Ti/InP is attributed to the reduced charge-transfer resistance and the increased band bending at the MoSx/Ti/InP/electrolyte interface. In addition, the MoSx/Ti/InP photocathodes function stably for PEC water reduction under continuous light illumination over 2 h. Our study demonstrates an effective approach to develop high-PEC-performance InP photocathodes towards stable solar hydrogen production.

  2. Confined Flocculation of Ionic Pollutants by Poly(L-dopa)-Based Polyelectrolyte Complexes in Hydrogel Beads for Three-Dimensional, Quantitative, Efficient Water Decontamination.

    PubMed

    Yu, Li; Liu, Xiaokong; Yuan, Weichang; Brown, Lauren Joan; Wang, Dayang

    2015-06-16

    The development of simple and recyclable adsorbents with high adsorption capacity is a technical imperative for water treatment. In this work, we have successfully developed new adsorbents for the removal of ionic pollutants from water via encapsulation of polyelectrolyte complexes (PECs) made from positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly(l-3,4-dihydroxyphenylalanine) (PDopa), obtained via the self-polymerization of l-3,4-dihydroxyphenylalanine (l-Dopa). Given the outstanding mass transport through the hydrogel host matrixes, the PDopa-PAH PEC guests loaded inside can effectively and efficiently remove various ionic pollutants, including heavy metal ions and ionic organic dyes, from water. The adsorption efficiency of the PDopa-PAH PECs can be quantitatively correlated to and tailored by the PDopa-to-PAH molar ratio. Because PDopa embodies one catechol group, one carboxyl group, and one amino group in each repeating unit, the resulting PDopa-PAH PECs exhibit the largest capacity of adsorption of heavy metal ions compared to available adsorbents. Because both PDopa and PAH are pH-sensitive, the PDopa-PAH PEC-loaded agarose hydrogel beads can be easily and completely recovered after the adsorption of ionic pollutants by adjusting the pH of the surrounding media. The present strategy is similar to the conventional process of using PECs to flocculate ionic pollutants from water, while in our system flocculation is confined to the agarose hydrogel beads, thus allowing easy separation of the resulting adsorbents from water.

  3. Extraintestinal Pathogenic Escherichia coli: A Combination of Virulence with Antibiotic Resistance

    PubMed Central

    Pitout, Johann D. D.

    2012-01-01

    Escherichia coli represents an incredible versatile and diverse enterobacterial species and can be subdivided into the following; (i) intestinal non-pathogenic, commensal isolates. (ii) Intestinal pathogenic isolates and (iii) extraintestinal pathogenic E. coli or ExPEC isolates. The presence to several putative virulence genes has been positively linked with the pathogenicity of ExPEC. E. coli remains one of the most frequent causes of nosocomial and community-acquired bacterial infections including urinary tract infections, enteric infections, and systemic infections in humans. ExPEC has emerged in 2000s as an important player in the resistance to antibiotics including the cephalosporins and fluoroquinolones. Most importantly among ExPEC is the increasing recognition of isolates producing “newer β-lactamases” that consists of plasmid-mediated AmpC β-lactamases (e.g., CMY), extended-spectrum β-lactamases (e.g., CTX-M), and carbapenemases (e.g., NDM). This review will highlight aspects of virulence associated with ExPEC, provide a brief overview of plasmid-mediated resistance to β-lactams including the characteristics of the successful international sequence types such as ST38, ST131, ST405, and ST648 among ExPEC. PMID:22294983

  4. Engineering MoSx/Ti/InP Hybrid Photocathode for Improved Solar Hydrogen Production

    PubMed Central

    Li, Qiang; Zheng, Maojun; Zhong, Miao; Ma, Liguo; Wang, Faze; Ma, Li; Shen, Wenzhong

    2016-01-01

    Due to its direct band gap of ~1.35 eV, appropriate energy band-edge positions, and low surface-recombination velocity, p-type InP has attracted considerable attention as a promising photocathode material for solar hydrogen generation. However, challenges remain with p-type InP for achieving high and stable photoelectrochemical (PEC) performances. Here, we demonstrate that surface modifications of InP photocathodes with Ti thin layers and amorphous MoSx nanoparticles can remarkably improve their PEC performances. A high photocurrent density with an improved PEC onset potential is obtained. Electrochemical impedance analyses reveal that the largely improved PEC performance of MoSx/Ti/InP is attributed to the reduced charge-transfer resistance and the increased band bending at the MoSx/Ti/InP/electrolyte interface. In addition, the MoSx/Ti/InP photocathodes function stably for PEC water reduction under continuous light illumination over 2 h. Our study demonstrates an effective approach to develop high-PEC-performance InP photocathodes towards stable solar hydrogen production. PMID:27431993

  5. Polyelectrolyte Complex Hydrogels: Self-assembly and the Influence of Charged and Neutral Blocks

    NASA Astrophysics Data System (ADS)

    Srivastava, Samanvaya; Goldfeld, David; Levi, Adam; Mao, Jun; Chen, Wei; Tirrell, Matthew

    Polyelectrolyte complexes (PEC) form when oppositely charged polyelectrolyte chains spontaneously associate and phase separate in aqueous mediums. Bulk phase separation of the PECs can be evaded by combining one or both of the polyelectrolytes with a neutral polymer, thus engineering pathways for self-assembled PEC micelles and hydrogels. The PEC domains in these assemblies can encapsulate therapeutics as well as genetic materials and thus have tremendous potential in drug delivery and tissue engineering applications. We will present insights on the equilibrium structure and self-assembly kinetics of PEC hydrogels with large-scale ordering of the nanoscale PEC domains through detailed structure characterization and rheology studies of self-assembled materials comprising of functionalized polyallyl glycidyl ethers (PAGE) connected to either single poly(ethylene glycol) (PEG) chain to form diblock copolymers or as functionalized end-groups on a triblock copolymer with a PEG midblock. The effect of key parameters such as polymer concentration, polymer block lengths, salt, ionic strength, and degree of charge mismatch on the equilibrium materials properties will be discussed, with a special emphasis on the structure-defining role of the charged blocks and the structure-directing role of neutral blocks. Additionally, interesting similarities, and differences between structures and dynamics of hydrogels comprising diblock and corresponding triblock polyelectrolytes, respectively, will be discussed.

  6. Photoelectrocatalytic oxidation of rhodamine B in aqueous solution using Ti/TiO2 mesh photoelectrodes.

    PubMed

    Li, X Z; Liu, H L; Li, F B; Mak, C L

    2002-01-01

    To further improve the photooxidation techniques for water and waste-water purification, a Ti/TiO2 mesh electrode, was successfully prepared by anodizing Ti mesh in 0.5M H2SO4 solution. The structural and surface morphology of the Ti/TiO2 electrode was examined by Raman spectroscopy and scanning electronic microscopy (SEM) respectively. The examination results indicated that its structure and properties were affected by its growth rate in the anodization process, and anatase TiO2 was dominant in its composition. The photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation of rhodamine B in aqueous solution using the Ti/TiO2 electrode were investigated and compared. The experimental results demonstrated that the PEC oxidation by applying an electrical bias between the Ti/TiO2 electrode and Pt electrode could significantly enhance the degradation rate of rhodamine B compared with the PC oxidation. It was found that the best performance of PEC oxidation was achieved by applying the electrical bias of 0.6 V. The mechanism of rhodamine B degradation in the PEC process was discussed by studying the changes of absorbance spectrum and proton nuclear magnetic resonance spectroscopy of rhodamine B during the PEC degradation. The experimental results illustrated that both de-ethylation and chromogen destruction of rhodamine B under UV-light irradiation in the PEC degradation took place simultaneously.

  7. Extraintestinal Pathogenic Escherichia coli, a Common Human Pathogen: Challenges for Vaccine Development and Progress in the Field.

    PubMed

    Poolman, Jan T; Wacker, Michael

    2016-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) is the most common gram-negative bacterial pathogen in humans. ExPEC causes the vast majority of urinary tract infections (UTIs), is a leading cause of adult bacteremia, and is the second most common cause of neonatal meningitis. Increasing multidrug resistance among ExPEC strains constitutes a major obstacle to treatment and is implicated in increasing numbers of hospitalizations and deaths and increasing healthcare costs associated with ExPEC infections. An effective vaccine against ExPEC infection is urgently needed. The O antigen, a component of the surface lipopolysaccharide, has been identified as a promising vaccine target. With the availability of a novel bioconjugation technology it is expected that multivalent O antigen conjugate vaccines can be produced at industrial scale. Clinical proof of concept of a 4-valent O antigen conjugate vaccine is ongoing. An ExPEC vaccine effective against strains that are associated with major diseases and resistant to multiple drugs could be routinely delivered to individuals at risk of developing severe E. coli infection, such as elderly people, individuals undergoing abdominal surgery and prostatic biopsy procedures, and persons at risk of recurrent and/or complicated UTI.

  8. A previously unrecognized role of C3a in proteinuric progressive nephropathy.

    PubMed

    Morigi, Marina; Locatelli, Monica; Rota, Cinzia; Buelli, Simona; Corna, Daniela; Rizzo, Paola; Abbate, Mauro; Conti, Debora; Perico, Luca; Longaretti, Lorena; Benigni, Ariela; Zoja, Carlamaria; Remuzzi, Giuseppe

    2016-01-01

    Podocyte loss is the initial event in the development of glomerulosclerosis, the structural hallmark of progressive proteinuric nephropathies. Understanding mechanisms underlying glomerular injury is the key challenge for identifying novel therapeutic targets. In mice with protein-overload induced by bovine serum albumin (BSA), we evaluated whether the alternative pathway (AP) of complement mediated podocyte depletion and podocyte-dependent parietal epithelial cell (PEC) activation causing glomerulosclerosis. Factor H (Cfh(-/-)) or factor B-deficient mice were studied in comparison with wild-type (WT) littermates. WT+BSA mice showed podocyte depletion accompanied by glomerular complement C3 and C3a deposits, PEC migration to capillary tuft, proliferation, and glomerulosclerosis. These changes were more prominent in Cfh(-/-) +BSA mice. The pathogenic role of AP was documented by data that factor B deficiency preserved glomerular integrity. In protein-overload mice, PEC dysregulation was associated with upregulation of CXCR4 and GDNF/c-Ret axis. In vitro studies provided additional evidence of a direct action of C3a on proliferation and CXCR4-related migration of PECs. These effects were enhanced by podocyte-derived GDNF. In patients with proteinuric nephropathy, glomerular C3/C3a paralleled PEC activation, CXCR4 and GDNF upregulation. These results indicate that mechanistically uncontrolled AP complement activation is not dispensable for podocyte-dependent PEC activation resulting in glomerulosclerosis. PMID:27345360

  9. A previously unrecognized role of C3a in proteinuric progressive nephropathy

    PubMed Central

    Morigi, Marina; Locatelli, Monica; Rota, Cinzia; Buelli, Simona; Corna, Daniela; Rizzo, Paola; Abbate, Mauro; Conti, Debora; Perico, Luca; Longaretti, Lorena; Benigni, Ariela; Zoja, Carlamaria; Remuzzi, Giuseppe

    2016-01-01

    Podocyte loss is the initial event in the development of glomerulosclerosis, the structural hallmark of progressive proteinuric nephropathies. Understanding mechanisms underlying glomerular injury is the key challenge for identifying novel therapeutic targets. In mice with protein-overload induced by bovine serum albumin (BSA), we evaluated whether the alternative pathway (AP) of complement mediated podocyte depletion and podocyte-dependent parietal epithelial cell (PEC) activation causing glomerulosclerosis. Factor H (Cfh−/−) or factor B-deficient mice were studied in comparison with wild-type (WT) littermates. WT+BSA mice showed podocyte depletion accompanied by glomerular complement C3 and C3a deposits, PEC migration to capillary tuft, proliferation, and glomerulosclerosis. These changes were more prominent in Cfh−/− +BSA mice. The pathogenic role of AP was documented by data that factor B deficiency preserved glomerular integrity. In protein-overload mice, PEC dysregulation was associated with upregulation of CXCR4 and GDNF/c-Ret axis. In vitro studies provided additional evidence of a direct action of C3a on proliferation and CXCR4-related migration of PECs. These effects were enhanced by podocyte-derived GDNF. In patients with proteinuric nephropathy, glomerular C3/C3a paralleled PEC activation, CXCR4 and GDNF upregulation. These results indicate that mechanistically uncontrolled AP complement activation is not dispensable for podocyte-dependent PEC activation resulting in glomerulosclerosis. PMID:27345360

  10. Deterministic and probabilistic acute-based environmental risk assessment for naproxen for western Europe.

    PubMed

    Straub, Jürg Oliver; Stewart, Kathleen M

    2007-04-01

    An environmental risk assessment (ERA) was made for the common nonsteroidal anti-inflammatory drug naproxen. The ERA was performed according to deterministic and probabilistic methods, based on different predicted environmental concentrations (PECs) and measured environmental concentrations (MECs) on the exposure side as well as on published and newly elaborated acute ecotoxicity data on the effects side. Compilation of a large set of MECs allowed a qualification of the various PEC derivations. The European Medicines Evaluation Authority (EMEA) phase I PEC was shown to be far above realistic values, while the refined EMEA phase II (A and B) PECs were not too far from the 95th percentile MEC, in agreement with their nature as local PECs. The western European continental and regional PECs extrapolated based on actual use data, using the European Union system for the evaluation of substances, with the region reconfigured for Germany where most of the available European MECs are from, were in good to very close agreement with the median MECs. No risk to surface waters is apparent by any of the methodologies applied from the current use of naproxen; however, because only insufficient chronic ecotoxicity data are available, this is a preliminary conclusion.

  11. Engineering MoSx/Ti/InP Hybrid Photocathode for Improved Solar Hydrogen Production.

    PubMed

    Li, Qiang; Zheng, Maojun; Zhong, Miao; Ma, Liguo; Wang, Faze; Ma, Li; Shen, Wenzhong

    2016-01-01

    Due to its direct band gap of ~1.35 eV, appropriate energy band-edge positions, and low surface-recombination velocity, p-type InP has attracted considerable attention as a promising photocathode material for solar hydrogen generation. However, challenges remain with p-type InP for achieving high and stable photoelectrochemical (PEC) performances. Here, we demonstrate that surface modifications of InP photocathodes with Ti thin layers and amorphous MoSx nanoparticles can remarkably improve their PEC performances. A high photocurrent density with an improved PEC onset potential is obtained. Electrochemical impedance analyses reveal that the largely improved PEC performance of MoSx/Ti/InP is attributed to the reduced charge-transfer resistance and the increased band bending at the MoSx/Ti/InP/electrolyte interface. In addition, the MoSx/Ti/InP photocathodes function stably for PEC water reduction under continuous light illumination over 2 h. Our study demonstrates an effective approach to develop high-PEC-performance InP photocathodes towards stable solar hydrogen production. PMID:27431993

  12. Effect of farmorubicin both free and associated with poly(butylcyanoacrylate) nanoparticles on phagocytic and NK activity of peritoneal exudate cells from tumor-bearing mice.

    PubMed

    Simeonova, Margarita Y; Antcheva, Margarita N

    2007-05-01

    The effect of Epirubicin (farmorubicin, FR), either free or associated with poly(butylcyanoacrylate) nanoparticles (PBCN) upon the phagocytic and natural killer (NK) activity of peritoneal exudate cells (PECs) harvested from Lewis lung carcinoma (LLC)-bearing-mice was investigated. Phagocytic and NK activity were tested 72 and 96 h, respectively after the last four intraperitoneal (i.p.) injections of the tested compounds have been administered to the mice. Phagocytic activity was evaluated in vitro by phagocytic index and ingestion capacity using a phagocytic assay. NK activity was evaluated in a direct cytotoxic test, in which PECs were used as effector cells while human erythroleukemic K-562 cells were used as target cells. The phagocytic activity of PECs, harvested from tumor-bearing mice, was stimulated after treatment with FR free, FR associated with polymer nanoparticles and with unloaded PBCN. The NK activity of PECs was strongly stimulated by unloaded PBCN. FR both free and encapsulated into the polymer matrix during the polymerization of n-butylcyanoacrylate (n-BCA) stimulated the NK activity of PECs, while FR adsorbed onto nanoparticles restrained it. These results suggest that the association of FR with nanoparticles modifies selectively its immunomodulating ability without producing any significant immunological disturbances. The toxicity of some of FR polymer forms towards PECs, displaying NK activity, probably comes from the enhanced local drug concentration on the membrane surface of the immune cells. However, it is insufficient to preclude the use of nanoparticles as drug delivery system.

  13. Extraintestinal Pathogenic Escherichia coli, a Common Human Pathogen: Challenges for Vaccine Development and Progress in the Field

    PubMed Central

    Poolman, Jan T.; Wacker, Michael

    2016-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) is the most common gram-negative bacterial pathogen in humans. ExPEC causes the vast majority of urinary tract infections (UTIs), is a leading cause of adult bacteremia, and is the second most common cause of neonatal meningitis. Increasing multidrug resistance among ExPEC strains constitutes a major obstacle to treatment and is implicated in increasing numbers of hospitalizations and deaths and increasing healthcare costs associated with ExPEC infections. An effective vaccine against ExPEC infection is urgently needed. The O antigen, a component of the surface lipopolysaccharide, has been identified as a promising vaccine target. With the availability of a novel bioconjugation technology it is expected that multivalent O antigen conjugate vaccines can be produced at industrial scale. Clinical proof of concept of a 4-valent O antigen conjugate vaccine is ongoing. An ExPEC vaccine effective against strains that are associated with major diseases and resistant to multiple drugs could be routinely delivered to individuals at risk of developing severe E. coli infection, such as elderly people, individuals undergoing abdominal surgery and prostatic biopsy procedures, and persons at risk of recurrent and/or complicated UTI. PMID:26333944

  14. Sediment contamination of residential streams in the metropolitan kansas city area, USA: Part II. whole-sediment toxicity to the amphipod hyalella azteca

    USGS Publications Warehouse

    Tao, J.; Ingersoll, C.G.; Kemble, N.E.; Dias, J.R.; Murowchick, J.B.; Welker, G.; Huggins, D.

    2010-01-01

    This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects were explored. The sediments exhibited a low to moderate toxicity, with five samples identified as toxic to H. azteca. Metals did not likely cause the toxicity based on low concentrations of metals in the pore water and elevated concentrations of acid volatile sulfide in the sediments. Although individual polycyclic aromatic hydrocarbons (PAHs) frequently exceeded effect-based sediment quality guidelines [probable effect concentrations (PECs)], only four of the samples had a PEC quotient (PEC-Q) for total PAHs over 1.0 and only one of these four samples was identified as toxic. For the mean PEC-Q for organochlorine compounds (chlordane, dieldrin, sum DDEs), 4 of the 12 samples with a mean PEC-Q above 1.0 were toxic and 4 of the 8 samples with a mean PEC-Q above 3.0 were toxic. Additionally, four of eight samples were toxic, with a mean PEC-Q above 1.0 based on metals, PAHs, polychlorinated biphenyls (PCBs), and organochlorine pesticides. The increase in the incidence of toxicity with the increase in the mean PEC-Q based on organochlorine pesticides or based on metals, PAHs, PCBs, and organochlorine pesticides suggests that organochlorine pesticides might have contributed to the observed toxicity and that the use of a mean PEC-Q, rather than PEC-Qs for individual compounds, might be more informative in predicting toxic effects. Our study shows that stream sediments subject to predominant nonpoint sources contamination can be toxic and that many factors, including analysis of a full suite of PAHs and pesticides of both past and present urban applications and the origins of

  15. Gallium arsenide modulates proteolytic cathepsin activities and antigen processing by macrophages.

    PubMed

    Lewis, T A; Hartmann, C B; McCoy, K L

    1998-09-01

    Gallium arsenide (GaAs) is a semiconductor utilized in the electronics industry. Chemical exposure of animals causes a local inflammatory reaction, but systemic immunosuppression. Mice were administered i.p. 200 mg/kg GaAs crystals or latex beads, or vehicle. Five days after exposure, splenic macrophages were defective, whereas thioglycolate-elicited peritoneal macrophages (PEC) were more efficient in processing the Ag, pigeon cytochrome c, than vehicle control macrophages. Various aspects of the MHC class II Ag-processing pathway were examined. Both macrophage populations normally presented a peptide fragment to the CD4+ T cells. Surface MHC class II expression on the PEC was up-regulated, but splenic cells had normal MHC class II expression. PEC had elevated levels of glutathione and cysteine, major physiologic reducing thiols. However, the cysteine content of splenic macrophages was diminished. Proteolytic activities of aspartyl cathepsin D, and thiol cathepsins B and L were decreased significantly in splenic macrophages. On the other hand, thiol cathepsin activities were increased selectively in PEC. Latex bead-exposed PEC were not more potent APC, and their thiol cathepsin activities were unchanged, indicating that phagocytosis and nonspecific irritation were not responsible. The phenotype of PEC directly exposed to GaAs mirrored cytokine-activated macrophages, in contrast to splenic macrophages from a distant site. Therefore, GaAs exposure differentially modulated cathepsin activities in splenic macrophages and PEC, which correlated with their Ag-processing efficiency. Perhaps such distinct alterations may contribute to the local inflammation and systemic immunotoxicity caused by chemical exposure.

  16. Unique features of Erwinia chrysanthemi (Dickeya dadantii) RA3B genes involved in the blue indigoidine production.

    PubMed

    Chu, Mu-Kuei; Lin, Lee-Fong; Twu, Chung-Shing; Lin, Rong-Hwa; Lin, Yuan-Chuen; Hsu, Shih-Tien; Tzeng, Kuo-Ching; Huang, Hsiou-Chen

    2010-08-20

    Erwinia chrysanthemi (Ech) RA3B produces a large amount of blue indigoidine. Using Tn5-induced mutagenesis, three indigoidine-deficient mutants were generated. Followed by library screening, a 5.8kb fragment complemented mutants for indigoidine synthesis was cloned. This fragment contains four complete open-reading frames (ORFs), pecS, pecM, idgA, and idgB, and two partial ORFs, argG, and idgC. These genes are nearly identical to those in strain Ech3937. Primer extension assays demonstrated a clear transcriptional start site prior to idgA, while no promoter preceding idgB and idgC was detected, suggesting that idgA, idgB, and idgC are organized as one transcription unit. In contrast, indAB is separated from indC in Ech3937. Interestingly, an ERIC sequence was present between idgB and idgC in place of the promoter region of the homolog indC, which may contribute to the loss of promoter activity in RA3B. Futhermore, idgB mutant displayed much lighter blue color, while indB mutant appeared white on media. Overexpression of pecS in RA3B resulted in significantly reduced indigoidine production and idgC transcript. Moreover, gel shift and luxAB reporter assays revealed that PecS specifically binds to the sequence preceding idgA and inhibits gene expression, which is consistent with the results observed in Ech3937.

  17. Metagenomic analysis of sediments under seaports influence in the Equatorial Atlantic Ocean.

    PubMed

    Tavares, Tallita Cruz Lopes; Normando, Leonardo Ribeiro Oliveira; de Vasconcelos, Ana Tereza Ribeiro; Gerber, Alexandra Lehmkuhl; Agnez-Lima, Lucymara Fassarella; Melo, Vânia Maria Maciel

    2016-07-01

    Maritime ports are anthropogenic interventions capable of causing serious alterations in coastal ecosystems. In this study, we examined the benthic microbial diversity and community structure under the influence of two maritime ports, Mucuripe (MUC) and Pecém (PEC), at Equatorial Atlantic Ocean in Northeast Brazil. Those seaports differ in architecture, time of functioning, cargo handling and contamination. The microbiomes from MUC and PEC were also compared in silico to 11 other globally distributed marine microbiomes. The comparative analysis of operational taxonomic units (OTUs) retrieved by PCR-DGGE showed that MUC presents greater richness and β diversity of Bacteria and Archaea than PEC. In line with these results, metagenomic analysis showed that MUC and PEC benthic microbial communities share the main common bacterial phyla found in coastal environments, although can be distinguish by greater abundance of Cyanobacteria in MUC and Deltaproteobacteria in PEC. Both ports differed in Archaea composition, being PEC port sediments dominated by Thaumarchaeota. The microbiomes showed little divergence in their potential metabolic pathways, although shifts on the microbial taxonomic signatures involved in nitrogen and sulphur metabolic pathways were observed. The comparative analysis of different benthic marine metagenomes from Brazil, Australia and Mexico grouped them by the geographic location rather than by the type of ecosystem, although at phylum level seaport sediments share a core microbiome constituted by Proteobacteria, Cyanobacteria, Actinobacteria, Tenericuteres, Firmicutes, Bacteriodetes and Euryarchaeota. Our results suggest that multiple physical and chemical factors acting on sediments as a result of at least 60years of port operation play a role in shaping the benthic microbial communities at taxonomic level, but not at functional level.

  18. Metagenomic analysis of sediments under seaports influence in the Equatorial Atlantic Ocean.

    PubMed

    Tavares, Tallita Cruz Lopes; Normando, Leonardo Ribeiro Oliveira; de Vasconcelos, Ana Tereza Ribeiro; Gerber, Alexandra Lehmkuhl; Agnez-Lima, Lucymara Fassarella; Melo, Vânia Maria Maciel

    2016-07-01

    Maritime ports are anthropogenic interventions capable of causing serious alterations in coastal ecosystems. In this study, we examined the benthic microbial diversity and community structure under the influence of two maritime ports, Mucuripe (MUC) and Pecém (PEC), at Equatorial Atlantic Ocean in Northeast Brazil. Those seaports differ in architecture, time of functioning, cargo handling and contamination. The microbiomes from MUC and PEC were also compared in silico to 11 other globally distributed marine microbiomes. The comparative analysis of operational taxonomic units (OTUs) retrieved by PCR-DGGE showed that MUC presents greater richness and β diversity of Bacteria and Archaea than PEC. In line with these results, metagenomic analysis showed that MUC and PEC benthic microbial communities share the main common bacterial phyla found in coastal environments, although can be distinguish by greater abundance of Cyanobacteria in MUC and Deltaproteobacteria in PEC. Both ports differed in Archaea composition, being PEC port sediments dominated by Thaumarchaeota. The microbiomes showed little divergence in their potential metabolic pathways, although shifts on the microbial taxonomic signatures involved in nitrogen and sulphur metabolic pathways were observed. The comparative analysis of different benthic marine metagenomes from Brazil, Australia and Mexico grouped them by the geographic location rather than by the type of ecosystem, although at phylum level seaport sediments share a core microbiome constituted by Proteobacteria, Cyanobacteria, Actinobacteria, Tenericuteres, Firmicutes, Bacteriodetes and Euryarchaeota. Our results suggest that multiple physical and chemical factors acting on sediments as a result of at least 60years of port operation play a role in shaping the benthic microbial communities at taxonomic level, but not at functional level. PMID:27088626

  19. Modeling the Inactivation of Intestinal Pathogenic Escherichia coli O157:H7 and Uropathogenic E. coli in Ground Chicken by High Pressure Processing and Thymol.

    PubMed

    Chien, Shih-Yung; Sheen, Shiowshuh; Sommers, Christopher H; Sheen, Lee-Yan

    2016-01-01

    Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compared the resistance of iPEC (O157:H7) to UPEC in chicken meat using High Pressure Processing (HPP) in with (the hurdle concept) and without thymol essential oil as a sensitizer. UPEC was found slightly more resistant than E. coli O157:H7 (iPEC O157:H7) at 450 and 500 MPa. A central composite experimental design was used to evaluate the effect of pressure (300-400 MPa), thymol concentration (100-200 ppm), and pressure-holding time (10-20 min) on the inactivation of iPEC O157:H7 and UPEC in ground chicken. The hurdle approach reduced the high pressure levels and thymol doses imposed on the food matrices and potentially decreased food quality damaged after treatment. The quadratic equations were developed to predict the impact (lethality) on iPEC O157:H7 (R (2) = 0.94) and UPEC (R (2) = 0.98), as well as dimensionless non-linear models [Pr > F (<0.0001)]. Both linear and non-linear models were validated with data obtained from separated experiment points. All models may predict the inactivation/lethality within the same order of accuracy. However, the dimensionless non-linear models showed potential applications with parameters outside the central composite design ranges. The results provide useful information of both iPEC O157:H7 and UPEC in regard to how they may survive HPP in the presence or absence of thymol. The models may further assist regulatory agencies and food industry to assess the potential risk of iPEC O157:H7 and UPEC in ground chicken. PMID:27379050

  20. In vivo bioactivity of rhBMP-2 delivered with novel polyelectrolyte complexation shells assembled on an alginate microbead core template.

    PubMed

    Abbah, Sunny-Akogwu; Liu, Jing; Lam, Raymond W M; Goh, James C H; Wong, Hee-Kit

    2012-09-10

    Electrostatic interactions between polycations and polyanions are being explored to fabricate polyelectrolyte complexes (PEC) that could entrap and regulate the release of a wide range of biomolecules. Here, we report the in vivo application of PEC shells fabricated from three different polycations: poly-l-ornithine (PLO), poly-l-arginine (PLA) and DEAE-dextran (DEAE-D) to condense heparin on the surface of alginate microbeads and further control the delivery of recombinant human bone morphogenetic protein 2 (rhBMP-2) in spinal fusion application. We observed large differences in the behavior of PEC shells fabricated from the cationic polyamino acids (PLO and PLA) when compared to the cationic polysaccharide, DEAE-D. Whereas DEAE-D-based PEC shells eroded and released rhBMP-2 over 2 days in vitro, PLO- and PLA-based shells retained at least 60% of loaded rhBMP-2 after 3 weeks of incubation in phosphate-buffered saline. In vivo implantation in a rat model of posterolateral spinal fusion revealed robust bone formation in the PLO- and PLA-based PEC shell groups. This resulted in a significantly enhanced mechanical stability of the fused segments. However, bone induction and biomechanical stability of spine segments implanted with DEAE-D-based carriers were significantly inferior to both PLO- and PLA-based PEC shell groups (p<0.01). From these results, we conclude that PEC shells incorporating native heparin could be used for growth factor delivery in functional bone tissue engineering application and that PLA- and PLO-based complexes could represent superior options to DEAE-D for loading and in vivo delivery of bioactive BMP-2 in this approach.

  1. Longitudinal dependence of the seasonal variations of the topside ionospheric and plasmaspheric electron content: observations and model results

    NASA Astrophysics Data System (ADS)

    Zhang, Man-Lian; Liu, Libo; Ning, Baiqi; Wan, Weixing

    2016-07-01

    Radio signals transmitted from GPS satellite going through the ionization zone above the Earth will be refracted by the ionized components in the ionosphere and the plasmasphere, which would produce additional transfer delay and generate extra errors in satellite navigation and positioning, etc. These errors have strong relation with the total electron content (TEC) along the signal's travelling path. Therefore TEC is one of the most important parameters required by many users for different modern usage purposes. The topside ionospheric and plasmaspheric electron content makes a large contribution to TEC. In the present study, data for the year 2008 of the topside ionospheric and plasmaspheric electron content (PEC) between the height of 800-20200km above the Earth derived from the upward-looking TEC measurements of the precise orbit determination antenna on board the COSMIC low Earth orbit (LEO) satellites to the GPS signals are used to study the longitudinal dependence of the seasonal variations of PEC. A comparison study of the observed PEC with the IZMIRAN_Plas model results is also made. Our study showed that PEC shows different seasonal variations at different longitudinal sectors: for the 240°E-60°E longitudinal sector, PEC shows a strong annual variation with lowest value in the June solstice and highest value in the December solstice months; In contrast, very weak seasonal variations are observed for PEC at 60°E-240°E longitudinal sector; Comparison study showed that this longitudinal dependence feature of the observed PEC's seasonal variation is not well captured by the IZMIRAN_Plas model result. Acknowledgments This research was supported by the National Natural Science Foundation of China (NSFC No. 41274163)

  2. The Genome Sequence of Avian Pathogenic Escherichia coli Strain O1:K1:H7 Shares Strong Similarities with Human Extraintestinal Pathogenic E. coli Genomes▿

    PubMed Central

    Johnson, Timothy J.; Kariyawasam, Subhashinie; Wannemuehler, Yvonne; Mangiamele, Paul; Johnson, Sara J.; Doetkott, Curt; Skyberg, Jerod A.; Lynne, Aaron M.; Johnson, James R.; Nolan, Lisa K.

    2007-01-01

    Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regardless of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease in humans. Here, we begin to test the hypothesis that certain APEC strains possess potential to cause human urinary tract infection through virulence genotyping of 1,000 APEC and UPEC strains, generation of the first complete genomic sequence of an APEC (APEC O1:K1:H7) strain, and comparison of this genome to all available human ExPEC genomic sequences. The genomes of APEC O1 and three human UPEC strains were found to be remarkably similar, with only 4.5% of APEC O1's genome not found in other sequenced ExPEC genomes. Also, use of multilocus sequence typing showed that some of the sequenced human ExPEC strains were more like APEC O1 than other human ExPEC strains. This work provides evidence that at least some human and avian ExPEC strains are highly similar to one another, and it supports the possibility that a food-borne link between some APEC and UPEC strains exists. Future studies are necessary to assess the ability of APEC to overcome the hurdles necessary for such a food-borne transmission, and epidemiological studies are required to confirm that such a phenomenon actually occurs. PMID:17293413

  3. Photoelectrocatalytic decomposition of ethylene using TiO2/activated carbon fiber electrode with applied pulsed direct current square-wave potential

    NASA Astrophysics Data System (ADS)

    Ye, Sheng-ying; Zheng, Sen-hong; Song, Xian-liang; Luo, Shu-can

    2015-06-01

    Removing ethylene (C2H4) from the atmosphere of storage facilities for fruits and vegetable is one of the main challenges in their postharvest handling for maximizing their freshness, quality, and shelf life. In this study, we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas by applying a pulsed direct current DC square-wave (PDCSW) potential and by using a Nafion-based PEC cell. The cell utilized a titanium dioxide (TiO2) photocatalyst or γ-irradiated TiO2 (TiO2*) loaded on activated carbon fiber (ACF) as a photoelectrode. The apparent rate constant of a pseudo-first-order reaction (K) was used to describe the PEC degradation of ethylene. Parameters of the potential applied to the PEC cell in a reactor that affect the degradation efficiency in terms of the K value were studied. These parameters were frequency, duty cycle, and voltage. Ethylene degradation by application of a constant PDCSW potential to the PEC electrode of either TiO2/ACF cell or TiO2*/ACF cell enhanced the efficiency of photocatalytic degradation and PEC degradation. Gamma irradiation of TiO2 in the electrode and the applied PDCSW potential synergistically increased the K value. Independent variables (frequency, duty cycle, and voltage) of the PEC cell fabricated from TiO2 subjected 20 kGy γ radiation were optimized to maximize the K value by using response surface methodology with quadratic rotation-orthogonal composite experimental design. Optimized conditions were as follows: 358.36 Hz frequency, 55.79% duty cycle, and 64.65 V voltage. The maximum K value attained was 4.4 × 10-4 min-1.

  4. Extraintestinal Pathogenic and Antimicrobial-Resistant Escherichia coli Contamination of 56 Public Restrooms in the Greater Minneapolis-St. Paul Metropolitan Area.

    PubMed

    Mohamed, Muhanad; Owens, Kris; Gajewski, Abby; Clabots, Connie; Johnston, Brian; Thuras, Paul; Kuskowski, Michael A; Johnson, James R

    2015-07-01

    How extraintestinal pathogenic Escherichia coli (ExPEC) and antimicrobial-resistant E. coli disseminate through the population is undefined. We studied public restrooms for contamination with E. coli and ExPEC in relation to source and extensively characterized the E. coli isolates. For this, we cultured 1,120 environmental samples from 56 public restrooms in 33 establishments (obtained from 10 cities in the greater Minneapolis-St. Paul, MN, metropolitan area in 2003) for E. coli and compared ecological data with culture results. Isolates underwent virulence genotyping, phylotyping, clonal typing, pulsed-field gel electrophoresis (PFGE), and disk diffusion antimicrobial susceptibility testing. Overall, 168 samples (15% from 89% of restrooms) fluoresced, indicating presumptive E. coli: 25 samples (2.2% from 32% of restrooms) yielded E. coli isolates, and 10 samples (0.9% from 16% of restrooms) contained ExPEC. Restroom category and cleanliness level significantly predicted only fluorescence, gender predicted fluorescence and E. coli, and feces-like material and toilet-associated sites predicted all three endpoints. Of the 25 E. coli isolates, 7 (28%) were from phylogenetic group B2(virulence-associated), and 8 (32%) were ExPEC. ExPEC isolates more commonly represented group B2 (50% versus 18%) and had significantly higher virulence gene scores than non-ExPEC isolates. Six isolates (24%) exhibited ≥3-class antibiotic resistance, 10 (40%) represented classic human-associated sequence types, and one closely resembled reference human clinical isolates by pulsed-field gel electrophoresis. Thus, E. coli, ExPEC, and antimicrobial-resistant E. coli sporadically contaminate public restrooms, in ways corresponding with restroom characteristics and within-restroom sites. Such restroom-source E. coli strains likely reflect human fecal contamination, may pose a health threat, and may contribute to population-wide dissemination of such strains.

  5. A Killed, Genetically Engineered Derivative of a Wild-Type Extraintestinal Pathogenic E. coli strain is a Vaccine Candidate

    PubMed Central

    Russo, Thomas A.; Beanan, Janet M.; Olson, Ruth; Genagon, Stacy A.; MacDonald, Ulrike; Cope, John J.; Davidson, Bruce A.; Johnston, Brian; Johnson, James R.

    2007-01-01

    Infections due to extraintestinal pathogenic E. coli (ExPEC) result in significant morbidity, mortality and increased healthcare costs. An efficacious vaccine against ExPEC would be desirable. In this report we explore the use of killed-whole E. coli as a vaccine immunogen. Given the diversity of capsule and O-antigens in ExPEC we have hypothesized that alternative targets are viable vaccine candidates. We have also hypothesized that immunization with a genetically engineered strain that is deficient in the capsule and O-antigen will generate a greater immune response against antigens other than the capsular and O-antigen epitopes than a wild-type strain. Lastly, we hypothesize that mucosal immunization with killed E. coli has the potential to generate a significant immune response. In this study we demonstrated that nasal immunization with a formalin-killed ExPEC derivative deficient in capsule and O-antigen results in a significantly greater overall humoral response compared to its wild-type derivative (which demonstrates that capsule and/or the O-antigen impede the development of an optimal humoral immune response) and a significantly greater immune response against non-capsular and O-antigen epitopes. These antibodies also bound to a subset of heterologous ExPEC strains and enhanced neutrophil-mediated bactericidal activity against the homologous and a heterologous strain. Taken together these studies support the concept that formalin-killed genetically engineered ExPEC derivatives are whole cell vaccine candidates to prevent infections due to ExPEC. PMID:17306426

  6. Extraintestinal Pathogenic and Antimicrobial-Resistant Escherichia coli Contamination of 56 Public Restrooms in the Greater Minneapolis-St. Paul Metropolitan Area

    PubMed Central

    Owens, Kris; Gajewski, Abby; Clabots, Connie; Johnston, Brian; Thuras, Paul; Kuskowski, Michael A.; Johnson, James R.

    2015-01-01

    How extraintestinal pathogenic Escherichia coli (ExPEC) and antimicrobial-resistant E. coli disseminate through the population is undefined. We studied public restrooms for contamination with E. coli and ExPEC in relation to source and extensively characterized the E. coli isolates. For this, we cultured 1,120 environmental samples from 56 public restrooms in 33 establishments (obtained from 10 cities in the greater Minneapolis-St. Paul, MN, metropolitan area in 2003) for E. coli and compared ecological data with culture results. Isolates underwent virulence genotyping, phylotyping, clonal typing, pulsed-field gel electrophoresis (PFGE), and disk diffusion antimicrobial susceptibility testing. Overall, 168 samples (15% from 89% of restrooms) fluoresced, indicating presumptive E. coli: 25 samples (2.2% from 32% of restrooms) yielded E. coli isolates, and 10 samples (0.9% from 16% of restrooms) contained ExPEC. Restroom category and cleanliness level significantly predicted only fluorescence, gender predicted fluorescence and E. coli, and feces-like material and toilet-associated sites predicted all three endpoints. Of the 25 E. coli isolates, 7 (28%) were from phylogenetic group B2(virulence-associated), and 8 (32%) were ExPEC. ExPEC isolates more commonly represented group B2 (50% versus 18%) and had significantly higher virulence gene scores than non-ExPEC isolates. Six isolates (24%) exhibited ≥3-class antibiotic resistance, 10 (40%) represented classic human-associated sequence types, and one closely resembled reference human clinical isolates by pulsed-field gel electrophoresis. Thus, E. coli, ExPEC, and antimicrobial-resistant E. coli sporadically contaminate public restrooms, in ways corresponding with restroom characteristics and within-restroom sites. Such restroom-source E. coli strains likely reflect human fecal contamination, may pose a health threat, and may contribute to population-wide dissemination of such strains. PMID:25911488

  7. Modeling the Inactivation of Intestinal Pathogenic Escherichia coli O157:H7 and Uropathogenic E. coli in Ground Chicken by High Pressure Processing and Thymol.

    PubMed

    Chien, Shih-Yung; Sheen, Shiowshuh; Sommers, Christopher H; Sheen, Lee-Yan

    2016-01-01

    Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compared the resistance of iPEC (O157:H7) to UPEC in chicken meat using High Pressure Processing (HPP) in with (the hurdle concept) and without thymol essential oil as a sensitizer. UPEC was found slightly more resistant than E. coli O157:H7 (iPEC O157:H7) at 450 and 500 MPa. A central composite experimental design was used to evaluate the effect of pressure (300-400 MPa), thymol concentration (100-200 ppm), and pressure-holding time (10-20 min) on the inactivation of iPEC O157:H7 and UPEC in ground chicken. The hurdle approach reduced the high pressure levels and thymol doses imposed on the food matrices and potentially decreased food quality damaged after treatment. The quadratic equations were developed to predict the impact (lethality) on iPEC O157:H7 (R (2) = 0.94) and UPEC (R (2) = 0.98), as well as dimensionless non-linear models [Pr > F (<0.0001)]. Both linear and non-linear models were validated with data obtained from separated experiment points. All models may predict the inactivation/lethality within the same order of accuracy. However, the dimensionless non-linear models showed potential applications with parameters outside the central composite design ranges. The results provide useful information of both iPEC O157:H7 and UPEC in regard to how they may survive HPP in the presence or absence of thymol. The models may further assist regulatory agencies and food industry to assess the potential risk of iPEC O157:H7 and UPEC in ground chicken.

  8. Modeling the Inactivation of Intestinal Pathogenic Escherichia coli O157:H7 and Uropathogenic E. coli in Ground Chicken by High Pressure Processing and Thymol

    PubMed Central

    Chien, Shih-Yung; Sheen, Shiowshuh; Sommers, Christopher H.; Sheen, Lee-Yan

    2016-01-01

    Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compared the resistance of iPEC (O157:H7) to UPEC in chicken meat using High Pressure Processing (HPP) in with (the hurdle concept) and without thymol essential oil as a sensitizer. UPEC was found slightly more resistant than E. coli O157:H7 (iPEC O157:H7) at 450 and 500 MPa. A central composite experimental design was used to evaluate the effect of pressure (300–400 MPa), thymol concentration (100–200 ppm), and pressure-holding time (10–20 min) on the inactivation of iPEC O157:H7 and UPEC in ground chicken. The hurdle approach reduced the high pressure levels and thymol doses imposed on the food matrices and potentially decreased food quality damaged after treatment. The quadratic equations were developed to predict the impact (lethality) on iPEC O157:H7 (R2 = 0.94) and UPEC (R2 = 0.98), as well as dimensionless non-linear models [Pr > F (<0.0001)]. Both linear and non-linear models were validated with data obtained from separated experiment points. All models may predict the inactivation/lethality within the same order of accuracy. However, the dimensionless non-linear models showed potential applications with parameters outside the central composite design ranges. The results provide useful information of both iPEC O157:H7 and UPEC in regard to how they may survive HPP in the presence or absence of thymol. The models may further assist regulatory agencies and food industry to assess the potential risk of iPEC O157:H7 and UPEC in ground chicken. PMID:27379050

  9. Heme oxygenase-1-mediated autophagy protects against pulmonary endothelial cell death and development of emphysema in cadmium-treated mice.

    PubMed

    Surolia, Ranu; Karki, Suman; Kim, Hyunki; Yu, Zhihong; Kulkarni, Tejaswini; Mirov, Sergey B; Carter, A Brent; Rowe, Steven M; Matalon, Sadis; Thannickal, Victor J; Agarwal, Anupam; Antony, Veena B

    2015-08-01

    Pulmonary exposure to cadmium, a major component of cigarette smoke, has a dramatic impact on lung function and the development of emphysema. Cigarette smoke exposure induces heme oxygenase-1 (HO-1), a cytoprotective enzyme. In this study, we employed a truncated mouse model of emphysema by intratracheal instillation of cadmium (CdCl2) solution (0.025% per 1 mg/kg body wt) in HO-1(+/+), HO-1(-/-), and overexpressing humanized HO-1 bacterial artificial chromosome (hHO-1BAC) mice. We evaluated the role of HO-1 in cadmium-induced emphysema in mice by analyzing histopathology, micro-computed tomography scans, and lung function tests. CdCl2-exposed HO-1(-/-) mice exhibited more severe emphysema compared with HO-1(+/+) or hHO-1BAC mice. Loss of pulmonary endothelial cells (PECs) from the alveolar capillary membrane is recognized to be a target in emphysema. PECs from HO-1(+/+), HO-1(-/-), and hHO-1BAC were employed to define the underlying molecular mechanism for the protection from emphysema by HO-1. Electron microscopy, expression of autophagic markers (microtubule-associated protein 1B-light chain 3 II, autophagy protein 5, and Beclin1) and apoptotic marker (cleaved caspase 3) suggested induction of autophagy and apoptosis in PECs after CdCl2 treatment. CdCl2-treated HO-1(-/-) PECs exhibited downregulation of autophagic markers and significantly increased cleaved caspase 3 expression and activity (∼4-fold higher). Moreover, hHO-1BAC PECs demonstrated upregulated autophagy and absence of cleaved caspase 3 expression or activity. Pretreatment of HO-1(+/+) PECs with rapamycin induced autophagy and resulted in reduced cell death upon cadmium treatment. Induction of autophagy following CdCl2 treatment was found to be protective from apoptotic cell death. HO-1 induced protective autophagy in PECs and mitigated cadmium-induced emphysema.

  10. Heme oxygenase-1-mediated autophagy protects against pulmonary endothelial cell death and development of emphysema in cadmium-treated mice

    PubMed Central

    Surolia, Ranu; Karki, Suman; Kim, Hyunki; Yu, Zhihong; Kulkarni, Tejaswini; Mirov, Sergey B.; Carter, A. Brent; Rowe, Steven M.; Matalon, Sadis; Thannickal, Victor J.; Agarwal, Anupam

    2015-01-01

    Pulmonary exposure to cadmium, a major component of cigarette smoke, has a dramatic impact on lung function and the development of emphysema. Cigarette smoke exposure induces heme oxygenase-1 (HO-1), a cytoprotective enzyme. In this study, we employed a truncated mouse model of emphysema by intratracheal instillation of cadmium (CdCl2) solution (0.025% per 1 mg/kg body wt) in HO-1+/+, HO-1−/−, and overexpressing humanized HO-1 bacterial artificial chromosome (hHO-1BAC) mice. We evaluated the role of HO-1 in cadmium-induced emphysema in mice by analyzing histopathology, micro-computed tomography scans, and lung function tests. CdCl2-exposed HO-1−/− mice exhibited more severe emphysema compared with HO-1+/+ or hHO-1BAC mice. Loss of pulmonary endothelial cells (PECs) from the alveolar capillary membrane is recognized to be a target in emphysema. PECs from HO-1+/+, HO-1−/−, and hHO-1BAC were employed to define the underlying molecular mechanism for the protection from emphysema by HO-1. Electron microscopy, expression of autophagic markers (microtubule-associated protein 1B-light chain 3 II, autophagy protein 5, and Beclin1) and apoptotic marker (cleaved caspase 3) suggested induction of autophagy and apoptosis in PECs after CdCl2 treatment. CdCl2-treated HO-1−/− PECs exhibited downregulation of autophagic markers and significantly increased cleaved caspase 3 expression and activity (∼4-fold higher). Moreover, hHO-1BAC PECs demonstrated upregulated autophagy and absence of cleaved caspase 3 expression or activity. Pretreatment of HO-1+/+ PECs with rapamycin induced autophagy and resulted in reduced cell death upon cadmium treatment. Induction of autophagy following CdCl2 treatment was found to be protective from apoptotic cell death. HO-1 induced protective autophagy in PECs and mitigated cadmium-induced emphysema. PMID:26071551

  11. Combining Quantitative Genetic Footprinting and Trait Enrichment Analysis to Identify Fitness Determinants of a Bacterial Pathogen

    PubMed Central

    Wiles, Travis J.; Norton, J. Paul; Russell, Colin W.; Dalley, Brian K.; Fischer, Kael F.; Mulvey, Matthew A.

    2013-01-01

    Strains of Extraintestinal Pathogenic Escherichia c oli (ExPEC) exhibit an array of virulence strategies and are a major cause of urinary tract infections, sepsis and meningitis. Efforts to understand ExPEC pathogenesis are challenged by the high degree of genetic and phenotypic variation that exists among isolates. Determining which virulence traits are widespread and which are strain-specific will greatly benefit the design of more effective therapies. Towards this goal, we utilized a quantitative genetic footprinting technique known as transposon insertion sequencing (Tn-seq) in conjunction with comparative pathogenomics to functionally dissect the genetic repertoire of a reference ExPEC isolate. Using Tn-seq and high-throughput zebrafish infection models, we tracked changes in the abundance of ExPEC variants within saturated transposon mutant libraries following selection within distinct host niches. Nine hundred and seventy bacterial genes (18% of the genome) were found to promote pathogen fitness in either a niche-dependent or independent manner. To identify genes with the highest therapeutic and diagnostic potential, a novel Trait Enrichment Analysis (TEA) algorithm was developed to ascertain the phylogenetic distribution of candidate genes. TEA revealed that a significant portion of the 970 genes identified by Tn-seq have homologues more often contained within the genomes of ExPEC and other known pathogens, which, as suggested by the first axiom of molecular Koch's postulates, is considered to be a key feature of true virulence determinants. Three of these Tn-seq-derived pathogen-associated genes—a transcriptional repressor, a putative metalloendopeptidase toxin and a hypothetical DNA binding protein—were deleted and shown to independently affect ExPEC fitness in zebrafish and mouse models of infection. Together, the approaches and observations reported herein provide a resource for future pathogenomics-based research and highlight the diversity of

  12. Zinc-Stabilized Chitosan-Chondroitin Sulfate Nanocomplexes for HIV-1 Infection Inhibition Application.

    PubMed

    Wu, Danjun; Ensinas, Agathe; Verrier, Bernard; Primard, Charlotte; Cuvillier, Armelle; Champier, Gaël; Paul, Stephane; Delair, Thierry

    2016-09-01

    Polyelectrolyte complexes (PECs) constituted of chitosan and chondroitin sulfate (ChonS) were formed by the one-shot addition of default amounts of polyanion to an excess of polycation. Key variables of the formulation process (e.g., degree of depolymerization, charge mixing ratio, the concentration, and pH of polyelectrolyte solutions) were optimized based on the PECs sizes and polydispersities. The PECs maintained their colloidal stability at physiological salt concentration and pH thanks to the complexation of polyelectrolytes with zinc(II) ion during the nanoPECs formation process. The PECs were capable of encapsulating an antiretroviral drug tenofovir (TF) with a minimal alteration on the colloidal stability of the dispersion. Moreover, the particle interfaces could efficiently be functionalized with anti-OVA or anti-α4β7 antibodies with conservation of the antibody biorecognition properties over 1 week of storage in PBS at 4 °C. In vitro cytotoxicity studies showed that zinc(II) stabilized chitosan-ChonS nanoPECs were noncytotoxic to human peripheral blood mononuclear cells (PBMCs), and in vitro antiviral activity test demonstrated that nanoparticles formulations led to a dose-dependent reduction of HIV-1 infection. Using nanoparticles as a drug carrier system decreases the IC50 (50% inhibitory concentration) from an aqueous TF of 4.35 μmol·L(-1) to 1.95 μmol·L(-1). Significantly, zinc ions in this system also exhibited a synergistic effect in the antiviral potency. These data suggest that chitosan-ChonS nanoPECs can be promising drug delivery system to improve the antiviral potency of drugs to the viral reservoirs for the treatment of HIV infection. PMID:27454202

  13. Fracturing fluid cleanup by controlled release of enzymes from polyelectrolyte complex nanoparticles

    NASA Astrophysics Data System (ADS)

    Barati Ghahfarokhi, Reza

    Guar-based polymer gels are used in the oil and gas industry to viscosify fluids used in hydraulic fracturing of production wells, in order to reduce leak-off of fluids and pressure, and improve the transport of proppants. After fracturing, the gel and associated filter cake must be degraded to very low viscosities using breakers to recover the hydraulic conductivity of the well. Enzymes are widely used to achieve this but injecting high concentrations of enzyme may result in premature degradation, or failure to gel; denaturation of enzymes at alkaline pH and high temperature conditions can also limit their applicability. In this study, application of polyelectrolyte nanoparticles for entrapping, carrying, releasing and protecting enzymes for fracturing fluids was examined. The objective of this research is to develop nano-sized carriers capable of carrying the enzymes to the filter cake, delaying the release of enzyme and protecting the enzyme against pH and temperature conditions inhospitable to native enzyme. Polyethylenimine-dextran sulfate (PEI-DS) polyelectrolyte complexes (PECs) were used to entrap two enzymes commonly used in the oil industry in order to obtain delayed release and to protect the enzyme from conditions inhospitable to native enzyme. Stability and reproducibility of PEC nanoparticles was assured over time. An activity measurement method was used to measure the entrapment efficiency of enzyme using PEC nanoparticles. This method was confirmed using a concentration measurement method (SDS-PAGE). Entrapment efficiencies of pectinase and a commercial high-temperature enzyme mixture in polyelectrolyte complex nanoparticles were maximized. Degradation, as revealed by reduction in viscoelastic moduli of borate-crosslinked hydroxypropyl guar (HPG) gel by commercial enzyme loaded in polyelectrolyte nanoparticles, was delayed, compared to equivalent systems where the enzyme mixture was not entrapped. This indicates that PEC nanoparticles delay the

  14. Similarly Lethal Strains of Extraintestinal Pathogenic Escherichia coli Trigger Markedly Diverse Host Responses in a Zebrafish Model of Sepsis

    PubMed Central

    Barber, Amelia E.; Fleming, Brittany A.

    2016-01-01

    ABSTRACT In individuals with sepsis, the infecting microbes are commonly viewed as generic inducers of inflammation while the host background is considered the primary variable affecting disease progression and outcome. To study the effects of bacterial strain differences on the maladaptive immune responses that are induced during sepsis, we employed a novel zebrafish embryo infection model using extraintestinal pathogenic Escherichia coli (ExPEC) isolates. These genetically diverse pathogens are a leading cause of sepsis and are becoming increasingly dangerous because of the rise of multidrug-resistant strains. Zebrafish infected with ExPEC isolates exhibit many of the pathophysiological features seen in septic human patients, including dysregulated inflammatory responses (cytokine storms), tachycardia, endothelial leakage, and progressive edema. However, only a limited subset of ExPEC isolates can trigger a sepsis-like state and death of the host when introduced into the bloodstream. Mirroring the situation in human patients, antibiotic therapy reduced ExPEC titers and improved host survival rates but was only effective within limited time frames that varied, depending on the infecting pathogen. Intriguingly, we find that phylogenetically distant but similarly lethal ExPEC isolates can stimulate markedly different host transcriptional responses, including disparate levels of inflammatory mediators. These differences correlate with the amounts of bacterial flagellin expression during infection, as well as differential activation of Toll-like receptor 5 by discrete flagellar serotypes. Altogether, this work establishes zebrafish as a relevant model of key aspects of human sepsis and highlights the ability of genetically distinct ExPEC isolates to induce divergent host responses independently of baseline host attributes. IMPORTANCE Sepsis is a life-threatening systemic inflammatory condition that is initiated by the presence of microorganisms in the bloodstream. In

  15. Similarly Lethal Strains of Extraintestinal Pathogenic Escherichia coli Trigger Markedly Diverse Host Responses in a Zebrafish Model of Sepsis.

    PubMed

    Barber, Amelia E; Fleming, Brittany A; Mulvey, Matthew A

    2016-01-01

    In individuals with sepsis, the infecting microbes are commonly viewed as generic inducers of inflammation while the host background is considered the primary variable affecting disease progression and outcome. To study the effects of bacterial strain differences on the maladaptive immune responses that are induced during sepsis, we employed a novel zebrafish embryo infection model using extraintestinal pathogenic Escherichia coli (ExPEC) isolates. These genetically diverse pathogens are a leading cause of sepsis and are becoming increasingly dangerous because of the rise of multidrug-resistant strains. Zebrafish infected with ExPEC isolates exhibit many of the pathophysiological features seen in septic human patients, including dysregulated inflammatory responses (cytokine storms), tachycardia, endothelial leakage, and progressive edema. However, only a limited subset of ExPEC isolates can trigger a sepsis-like state and death of the host when introduced into the bloodstream. Mirroring the situation in human patients, antibiotic therapy reduced ExPEC titers and improved host survival rates but was only effective within limited time frames that varied, depending on the infecting pathogen. Intriguingly, we find that phylogenetically distant but similarly lethal ExPEC isolates can stimulate markedly different host transcriptional responses, including disparate levels of inflammatory mediators. These differences correlate with the amounts of bacterial flagellin expression during infection, as well as differential activation of Toll-like receptor 5 by discrete flagellar serotypes. Altogether, this work establishes zebrafish as a relevant model of key aspects of human sepsis and highlights the ability of genetically distinct ExPEC isolates to induce divergent host responses independently of baseline host attributes. IMPORTANCE Sepsis is a life-threatening systemic inflammatory condition that is initiated by the presence of microorganisms in the bloodstream. In the

  16. Unveiling the photoelectrocatalytic inactivation mechanism of Escherichia coli: Convincing evidence from responses of parent and anti-oxidation single gene knockout mutants.

    PubMed

    Sun, Hongwei; Li, Guiying; An, Taicheng; Zhao, Huijun; Wong, Po Keung

    2016-01-01

    This study investigated photoelectrocatalytic (PEC) inactivation mechanism of bacteria using parental Escherichia coli (E. coli) BW25113 and its isogenic mutants deficient in catalase HPI (katG(-), JW3914-1) and Mn-SOD (sodA(-), JW3879-1). BW25113 in the mid-log phase was less susceptible to PEC inactivation than those in early-log and stationary phases, consistent with the peak activities of catalase and superoxide dismutase (SOD) at mid-log phase (30.6 and 13.0 Unit/ml/OD600). For different strains all in mid-log phase, PEC inactivation efficiency followed the order katG(-) > sodA(-) > BW25113, with the duration of 60, 60 and 90 min for complete inactivation of ∼2 × 10(7) CFU mL(-1) bacteria, respectively. Correspondingly, catalase and SOD levels of BW25113 were also higher than the mutants by 5.9 and 11.7 Unit/mL/OD600, respectively. Reactive oxygen species (ROSs) concentrations in PEC systems revealed that the inactivation performance coincided with H2O2 levels, rather than OH. Moreover, pre-incubation with H2O2 elevated catalase activities and PEC inactivation resistance of BW25113 were positively correlated. The above results indicated that H2O2 was the dominant PEC generated bactericide, and anti-oxidative enzymes especially catalase contributed greatly to the bacterial PEC resistance capacity. Further tests revealed that PEC treatment raised the intracellular ROSs concentration by more than 3 times, due to the permeated H2O2 and its intracellular derivative, OH. However, oxidative stress response of E. coli, such as increased catalase or SOD were not observed, perhaps because the ROSs overwhelmed the bacterial protective capacity. The accumulated ROSs subsequently caused oxidative damages to E. coli cells, including membrane damage, K(+) leakage, and protein oxidation. Compared with BW25113, the mutants experienced damages earlier and at higher levels, confirming the essential roles of catalase and SOD in the bacterial PEC resistance. PMID

  17. Unveiling the photoelectrocatalytic inactivation mechanism of Escherichia coli: Convincing evidence from responses of parent and anti-oxidation single gene knockout mutants.

    PubMed

    Sun, Hongwei; Li, Guiying; An, Taicheng; Zhao, Huijun; Wong, Po Keung

    2016-01-01

    This study investigated photoelectrocatalytic (PEC) inactivation mechanism of bacteria using parental Escherichia coli (E. coli) BW25113 and its isogenic mutants deficient in catalase HPI (katG(-), JW3914-1) and Mn-SOD (sodA(-), JW3879-1). BW25113 in the mid-log phase was less susceptible to PEC inactivation than those in early-log and stationary phases, consistent with the peak activities of catalase and superoxide dismutase (SOD) at mid-log phase (30.6 and 13.0 Unit/ml/OD600). For different strains all in mid-log phase, PEC inactivation efficiency followed the order katG(-) > sodA(-) > BW25113, with the duration of 60, 60 and 90 min for complete inactivation of ∼2 × 10(7) CFU mL(-1) bacteria, respectively. Correspondingly, catalase and SOD levels of BW25113 were also higher than the mutants by 5.9 and 11.7 Unit/mL/OD600, respectively. Reactive oxygen species (ROSs) concentrations in PEC systems revealed that the inactivation performance coincided with H2O2 levels, rather than OH. Moreover, pre-incubation with H2O2 elevated catalase activities and PEC inactivation resistance of BW25113 were positively correlated. The above results indicated that H2O2 was the dominant PEC generated bactericide, and anti-oxidative enzymes especially catalase contributed greatly to the bacterial PEC resistance capacity. Further tests revealed that PEC treatment raised the intracellular ROSs concentration by more than 3 times, due to the permeated H2O2 and its intracellular derivative, OH. However, oxidative stress response of E. coli, such as increased catalase or SOD were not observed, perhaps because the ROSs overwhelmed the bacterial protective capacity. The accumulated ROSs subsequently caused oxidative damages to E. coli cells, including membrane damage, K(+) leakage, and protein oxidation. Compared with BW25113, the mutants experienced damages earlier and at higher levels, confirming the essential roles of catalase and SOD in the bacterial PEC resistance.

  18. Similarly Lethal Strains of Extraintestinal Pathogenic Escherichia coli Trigger Markedly Diverse Host Responses in a Zebrafish Model of Sepsis.

    PubMed

    Barber, Amelia E; Fleming, Brittany A; Mulvey, Matthew A

    2016-01-01

    In individuals with sepsis, the infecting microbes are commonly viewed as generic inducers of inflammation while the host background is considered the primary variable affecting disease progression and outcome. To study the effects of bacterial strain differences on the maladaptive immune responses that are induced during sepsis, we employed a novel zebrafish embryo infection model using extraintestinal pathogenic Escherichia coli (ExPEC) isolates. These genetically diverse pathogens are a leading cause of sepsis and are becoming increasingly dangerous because of the rise of multidrug-resistant strains. Zebrafish infected with ExPEC isolates exhibit many of the pathophysiological features seen in septic human patients, including dysregulated inflammatory responses (cytokine storms), tachycardia, endothelial leakage, and progressive edema. However, only a limited subset of ExPEC isolates can trigger a sepsis-like state and death of the host when introduced into the bloodstream. Mirroring the situation in human patients, antibiotic therapy reduced ExPEC titers and improved host survival rates but was only effective within limited time frames that varied, depending on the infecting pathogen. Intriguingly, we find that phylogenetically distant but similarly lethal ExPEC isolates can stimulate markedly different host transcriptional responses, including disparate levels of inflammatory mediators. These differences correlate with the amounts of bacterial flagellin expression during infection, as well as differential activation of Toll-like receptor 5 by discrete flagellar serotypes. Altogether, this work establishes zebrafish as a relevant model of key aspects of human sepsis and highlights the ability of genetically distinct ExPEC isolates to induce divergent host responses independently of baseline host attributes. IMPORTANCE Sepsis is a life-threatening systemic inflammatory condition that is initiated by the presence of microorganisms in the bloodstream. In the

  19. Light harvesting proteins for solar fuel generation in bioengineered photoelectrochemical cells.

    PubMed

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used. PMID:24678669

  20. Spectroscopic Parameters of X3Σ-, a1Δ, and A'3Δ Electronic States of SO Radical

    NASA Astrophysics Data System (ADS)

    Wang, Jie-min; Feng, Heng-qiang; Sun, Jin-feng; Shi, De-heng; Zhu, Zun-lue

    2012-10-01

    The potential energy curves (PECs) of three low-lying electronic states (X3Σ, a1Δ, and A'3Δ) of SO radical have been studied by ab initio quantum chemical method. The calculations were carried out with the full valence complete active space self-consistent field method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with correlation-consistent basis sets. Effects of the core-valence correlation and relativistic corrections on the PECs are taken into account. The core-valence correlation correction is carried out with the cc-pCVDZ basis set. The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian approximation, and the correction is performed at the level of cc-pV5Z basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). These PECs are extrapolated to the complete basis set limit by the two-point energy extrapolation scheme. With these PECs, the spectroscopic parameters are determined.

  1. Genomic Microbial Epidemiology Is Needed to Comprehend the Global Problem of Antibiotic Resistance and to Improve Pathogen Diagnosis.

    PubMed

    Wyrsch, Ethan R; Roy Chowdhury, Piklu; Chapman, Toni A; Charles, Ian G; Hammond, Jeffrey M; Djordjevic, Steven P

    2016-01-01

    Contamination of waste effluent from hospitals and intensive food animal production with antimicrobial residues is an immense global problem. Antimicrobial residues exert selection pressures that influence the acquisition of antimicrobial resistance and virulence genes in diverse microbial populations. Despite these concerns there is only a limited understanding of how antimicrobial residues contribute to the global problem of antimicrobial resistance. Furthermore, rapid detection of emerging bacterial pathogens and strains with resistance to more than one antibiotic class remains a challenge. A comprehensive, sequence-based genomic epidemiological surveillance model that captures essential microbial metadata is needed, both to improve surveillance for antimicrobial resistance and to monitor pathogen evolution. Escherichia coli is an important pathogen causing both intestinal [intestinal pathogenic E. coli (IPEC)] and extraintestinal [extraintestinal pathogenic E. coli (ExPEC)] disease in humans and food animals. ExPEC are the most frequently isolated Gram negative pathogen affecting human health, linked to food production practices and are often resistant to multiple antibiotics. Cattle are a known reservoir of IPEC but they are not recognized as a source of ExPEC that impact human or animal health. In contrast, poultry are a recognized source of multiple antibiotic resistant ExPEC, while swine have received comparatively less attention in this regard. Here, we review what is known about ExPEC in swine and how pig production contributes to the problem of antibiotic resistance. PMID:27379026

  2. Genomic Microbial Epidemiology Is Needed to Comprehend the Global Problem of Antibiotic Resistance and to Improve Pathogen Diagnosis

    PubMed Central

    Wyrsch, Ethan R.; Roy Chowdhury, Piklu; Chapman, Toni A.; Charles, Ian G.; Hammond, Jeffrey M.; Djordjevic, Steven P.

    2016-01-01

    Contamination of waste effluent from hospitals and intensive food animal production with antimicrobial residues is an immense global problem. Antimicrobial residues exert selection pressures that influence the acquisition of antimicrobial resistance and virulence genes in diverse microbial populations. Despite these concerns there is only a limited understanding of how antimicrobial residues contribute to the global problem of antimicrobial resistance. Furthermore, rapid detection of emerging bacterial pathogens and strains with resistance to more than one antibiotic class remains a challenge. A comprehensive, sequence-based genomic epidemiological surveillance model that captures essential microbial metadata is needed, both to improve surveillance for antimicrobial resistance and to monitor pathogen evolution. Escherichia coli is an important pathogen causing both intestinal [intestinal pathogenic E. coli (IPEC)] and extraintestinal [extraintestinal pathogenic E. coli (ExPEC)] disease in humans and food animals. ExPEC are the most frequently isolated Gram negative pathogen affecting human health, linked to food production practices and are often resistant to multiple antibiotics. Cattle are a known reservoir of IPEC but they are not recognized as a source of ExPEC that impact human or animal health. In contrast, poultry are a recognized source of multiple antibiotic resistant ExPEC, while swine have received comparatively less attention in this regard. Here, we review what is known about ExPEC in swine and how pig production contributes to the problem of antibiotic resistance. PMID:27379026

  3. Effects of passing electric current on the elastic property of amorphous Cu{sub 50}Zr{sub 50} and Cu{sub 50}Ti{sub 50}

    SciTech Connect

    Takemoto, R.; Nagata, M.; Mizubayashi, H.

    1996-07-01

    For both amorphous Cu{sub 50}Zr{sub 50} and Cu{sub 50}Ti{sub 50}, the dynamic Young`s modulus M was found to increase under passing electric d.c.-current (PEC) with the current density i{sub d} below 5 {times} 10{sup 3} A/cm{sup 2}, suggesting that PEC induces internal stress. The i{sub d} dependence of M observed at low strain amplitude {epsilon}{sub t} was found to be identical to the {epsilon}{sub t} dependence of M without PEC after scaling between i{sub d} and {epsilon}{sub t}, giving Z* in the order of 10{sup 5}, where Z* is the apparent charge number measuring the electromigration force (EM-force) under PEC. The authors surmise that such a large Z* reflects the concentration of EM-force through the collective motion of many atoms, Z* = z*{xi}, for {xi} atoms with the charge number z* per atom. Application of this view to the observed effect of annealing on Z* gives {xi} as several hundreds in the as-quenched state. Based on the present results, the effects of PEC on the structural relaxation and crystallization processes reported are also discussed.

  4. Testing of NASA LaRC Materials under MISSE 6 and MISSE 7 Missions

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.

    2009-01-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Two lasers and a few optical components from NASA Langley Research Center (LaRC) were included in the MISSE 6 mission for long term exposure. MISSE 6 items were characterized and packed inside a ruggedized Passive Experiment Container (PEC) that resembles a suitcase. The PEC was tested for survivability due to launch conditions. MISSE 6 was transported to the international Space Station (ISS) via STS 123 on March 11. 2008. The astronauts successfully attached the PEC to external handrails of the ISS and opened the PEC for long term exposure to the space environment. The current plan is to bring the MISSE 6 PEC back to the Earth via STS 128 mission scheduled for launch in August 2009. Currently, preparations for launching the MISSE 7 mission are progressing. Laser and lidar components assembled on a flight-worthy platform are included from NASA LaRC. MISSE 7 launch is scheduled to be launched on STS 129 mission. This paper will briefly review recent efforts on MISSE 6 and MISSE 7 missions at NASA Langley Research Center (LaRC).

  5. Final Project Report

    SciTech Connect

    Zhang, Jin; Zhao, Yiping

    2014-12-05

    In this entire project period from 2005-2014, we have made significant progress in developing novel nanostructures of metal oxides (MOs) for solar hydrogen generation based on photoelectrochemical (PEC). Materials investigated are focused on 1D and 0D MO nanostructures of TiO2, WO3, ZnO, and Fe2O3 in conjunction with quantum dot (QD) sensitization and chemical doping (N or H) to alter their electronic band structures for both visible light absorption and for facilitating interfacial charge transport. In addition, we have used plasmonic metal nanostructures to enhance the PEC performance by improving light absorption of QDs via enhanced scattering of the plamonic metal. Most importantly, we have discovered a multipronged strategy for improving PEC performance: using plasmonic metal nanostructure to enhance light absorption, QDs to improve charge transfer, and chemical doping to increase charge transport in metal oxides for PEC. The combination is critical for overall high efficiency of PEC. This strategy is developed and demonstrated for the first time to our best knowledge.

  6. Fracture mode, microstructure and temperature-dependent elastic moduli for thermoelectric composites of PbTe PbS with SiC nanoparticle additions

    SciTech Connect

    Ni, Jennifer E; Case, Eldon D; Hogan, Timophy P.; Trejo, Rosa M; Lara-Curzio, Edgar; Kanatzidis, Mercouri G.

    2013-01-01

    Twenty-six (Pb0.95Sn0.05Te)0.92(PbS)0.08 0.055% PbI2 SiC nanoparticle (SiCnp) composite thermoelectric specimens were either hot pressed or pulsed electric current sintered (PECS). Bloating (a thermally induced increase in porosity, P, for as-densified specimens) was observed during annealing at temperatures >603 K for hot-pressed specimens and PECS-processed specimens from wet milled powders, but in contrast seven out of seven specimens densified by PECS from dry milled powders showed no observable bloating following annealing at temperatures up to 936 K. In this study, bloating in the specimens was accessed via thermal annealing induced changes in (i) porosity measured by scanning electron microscopy on fractured specimen surfaces, (ii) specimen volume and (iii) elastic moduli. The moduli were measured by resonant ultrasound spectroscopy. SiCnp additions (1 3.5 vol.%) changed the fracture mode from intergranular to transgranular, inhibited grain growth, and limited bloating in the wet milled PECS specimens. Inhibition of bloating likely occurs due to cleaning of contamination from powder particle surfaces via PECS processing which has been reported previously in the literature.

  7. Identification of protective and broadly conserved vaccine antigens from the genome of extraintestinal pathogenic Escherichia coli

    PubMed Central

    Rappuoli, Rino; Serino, Laura

    2010-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) are a common cause of disease in both mammals and birds. A vaccine to prevent such infections would be desirable given the increasing antibiotic resistance of these bacteria. We have determined the genome sequence of ExPEC IHE3034 (ST95) isolated from a case of neonatal meningitis and compared this to available genome sequences of other ExPEC strains and a few nonpathogenic E. coli. We found 19 genomic islands present in the genome of IHE3034, which are absent in the nonpathogenic E. coli isolates. By using subtractive reverse vaccinology we identified 230 antigens present in ExPEC but absent (or present with low similarity) in nonpathogenic strains. Nine antigens were protective in a mouse challenge model. Some of them were also present in other pathogenic non-ExPEC strains, suggesting that a broadly protective E. coli vaccine may be possible. The gene encoding the most protective antigen was detected in most of the E. coli isolates, highly conserved in sequence and found to be exported by a type II secretion system which seems to be nonfunctional in nonpathogenic strains. PMID:20439758

  8. Carbon-shell-decorated p-semiconductor PbMoO4 nanocrystals for efficient and stable photocathode of photoelectrochemical water reduction

    NASA Astrophysics Data System (ADS)

    Wang, Ligang; Tang, Hanqin; Tian, Yang

    2016-07-01

    Photoelectrochemical (PEC) water splitting using semiconductors is a promising method for the future scalable production of renewable hydrogen fuels. The critical issues in PEC water splitting include the development of the photoelectrode materials with high efficiency and long-term stability, especially for p-type semiconductor photocathodes. Herein, we report the use of citric acid (CA) pyrolysis to prepare carbon-shell-decorated PbMoO4 (C@PbMoO4) nanocrystals via a simple solvothermal method. Different carbon shell thicknesses below 10 nm were generated by varying the amount of CA in the precursor solution. In contrast, without using CA, bare PbMoO4 nanocrystals were obtained. The PEC experiments showed that 2-nm carbon shell could preferably improve the water splitting performance of PbMoO4: the photocurrent density of 2-nm C@PbMoO4 is nearly 2-fold high as that of bare PbMoO4 at 0 V versus reversible hydrogen electrode (RHE). The surface charge transfer efficiency of 2-nm C@PbMoO4 in the PEC process was tested to increase from 83% to 90.4%, the charge separation efficiency enhanced 56%, and the PEC stability also greatly increased compared to those of the bare PbMoO4 nanocrystals. This strategy could be applied to other p-type semiconducting photocathodes for low-cost solar-fuel-generation devices.

  9. A novel, biodegradable and reversible polyelectrolyte platform for topical-colonic delivery of pentosan polysulphate.

    PubMed

    Shah, Hardik K; Conkie, Jim A; Tait, Robert C; Johnson, James R; Wilson, Clive G

    2011-02-14

    The goal of the present work was to develop a swellable hydrogel colonic delivery system, which would maximise the availability of the therapeutic agent at a site of inflammation, especially where the water is scarce. A novel method was developed to manufacture a biodegradable and reversible polyelectrolyte complex (PEC) containing chitosan and poly acrylic-acid (PAA). The PEC was analysed using FTIR and DSC, which confirmed the formation of non-permanent swollen gel-network at an alkaline pH. Pentosan polysulphate (PPS) was incorporated in a PEC and an activated partial thromboplastin time assay was developed to measure the release of PPS from PEC. In vitro studies suggested that the release of PPS was dependent on the initial drug loading and the composition of the PEC. The gel strength of the swollen network, determined using a texture analyser, was dependent on polymer composition and the amount of PPS incorporated. Bacterial enzymes were collected from the rat caecum and colon for the digestion studies and characterised for glucosidase activity, glucuronidase activity and protein content. The digestion of the reversible polyelectrolyte complexes was measured using a dinitro salicylic acid assay and an increased release of drug was also confirmed in the presence of bacterial enzymes. PMID:21093555

  10. Polyelectrolyte complexes of poly[(2-dimethylamino) ethyl methacrylate]/chondroitin sulfate obtained at different pHs: I. Preparation, characterization, cytotoxicity and controlled release of chondroitin sulfate.

    PubMed

    Bonkovoski, Letícia C; Martins, Alessandro F; Bellettini, Ismael C; Garcia, Francielle P; Nakamura, Celso V; Rubira, Adley F; Muniz, Edvani C

    2014-12-30

    For the first time, polyelectrolyte complex based on poly[(2-dimethylamino) ethyl methacrylate] (PDMAEMA) and chondroitin sulfate (CS) was prepared. The properties of novel material and precursors were investigated by WAXS, FTIR, TGA, SEM and DLS analysis. The PDMAEMA/CS PECs presented hydrophilic-hydrophobic transition at pHs 6.0, 7.0 and 8.0 whereas the non-complexed PDMAEMA showed such a transition at pH 8.0 and not at pHs 6.0 and 7.0. Studies of CS release from PECs at pHs 6 and 8 confirmed that the samples possess the potential to release the CS in alkaline and not in acidic conditions. Since PECs are thermo-responsive due to the reduction of LCST caused by the increase in pH, the release of CS was dependent on temperature and pH factors. Cytotoxicity assays using healthy VERO cells showed that the complexation between CS and PDMAEMA increased the PECs' biocompatibility related to PDMAEMA. However, the biocompatibility depends on the amount of CS present in the PECs.

  11. Coordinated Hospital-Home Fecal Microbiota Transplantation via Percutaneous Endoscopic Cecostomy for Recurrent Steroid-Dependent Ulcerative Colitis

    PubMed Central

    Ni, Xiaodong; Fan, Shengxian; Zhang, Yongliang; Wang, Zhiming; Ding, Lan; Li, Yousheng; Li, Jieshou

    2016-01-01

    Since its introduction as an alternative intestinal microbiota alteration approach, fecal microbiota transplantation (FMT) has been increasingly used as a treatment of choice for patients with ulcerative colitis (UC), but no reports exist regarding FMT via percutaneous endoscopic cecostomy (PEC). This report describes the case of a 24-year-old man with a 7-year history of recurrent, steroid-dependent UC. He received FMT via PEC once per day for 1 month in the hospital. After the remission of gastrointestinal symptoms, he was discharged from the hospital and continued FMT via PEC twice per week for 3 months at home. The frequency of stools decreased, and the characteristics of stools improved soon thereafter. Enteral nutrition was regained after 1 week, and an oral diet was begun 1 month later. Two months after the FMT end point, the patient resumed a normal diet, with formed soft stools once per day. The follow-up colonoscopy showed normal mucus membranes; then, the PEC set was removed. On the subsequent 12 months follow-up, the patient resumed orthobiosis without any gastrointestinal discomfort and returned to work. This case emphasizes that FMT via PEC can not only induce remission but also shorten the duration of hospitalization and reduce the medical costs; therefore, this approach should be considered an alternative option for patients with UC. PMID:27282271

  12. Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin-copper(II) complex as the DNA intercalator.

    PubMed

    Li, Hongbo; Xue, Yan; Wang, Wei

    2014-04-15

    An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin-copper(II) complex intercalated into the poly(dT)-poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin-copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine-Hg(2+)-thymine coordination chemistry resulted in the dehybridization of poly(dT)-poly(dA) duplexes and then the intercalator quercetin-copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01 pmol L(-1) to 1.00 pmol L(-1) with the detection limit of 3.33 fmol L(-1). The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin-copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors. PMID:24291750

  13. A femtomolar level and highly selective 17β-estradiol photoelectrochemical aptasensor applied in environmental water samples analysis.

    PubMed

    Fan, Lifang; Zhao, Guohua; Shi, Huijie; Liu, Meichuan; Wang, Yanbin; Ke, Hongyang

    2014-05-20

    Driven by the urgent demand of determining low level of 17β-estradiol (E2) present in environment, a novel and ultrasensitive photoelectrochemical (PEC) sensing platform based on anti-E2 aptamer as the biorecognition element was developed onto CdSe nanoparticles-modified TiO2 nanotube arrays. The designed PEC aptasensor exhibits excellent performances in determination of E2 with a wide linear range of 0.05-15 pM. The detection limit of 33 fM is lower than the previous reports. The aptasensor manifests outstanding selectivity to E2 while used to detect seven other endocrine disrupting compounds that have similar structure or coexist with E2. The superior sensing behavior toward E2 can be attributed to the appropriate PEC sensing interface resulting from the preponderant tubular microstructure and excellent photoelectrical activity, the large packing density of aptamer on the sensing interface, as well as the high affinity of the aptamer to E2. The PEC aptasensor was applied successfully to determine E2 in environmental water samples without complicate sample pretreatments, and the analytical results showed good agreement with that determined by HPLC. Thus, a simple and rapid PEC technique for detection low level of E2 was established, having promising potential in monitoring environmental water pollution.

  14. Dermatan sulfate/chitosan polyelectrolyte complex with potential application in the treatment and diagnosis of vascular disease.

    PubMed

    Rasente, Rita Y; Imperiale, Julieta C; Lázaro-Martínez, Juan M; Gualco, Luciana; Oberkersch, Roxana; Sosnik, Alejandro; Calabrese, Graciela C

    2016-06-25

    Cardiovascular disease is the largest single cause of morbid-mortality in the world. However, there is still no pharmaceutical treatment that directly targets the blood vessel wall instead of just controlling the risk factors. Here, we produced polyelectrolyte complexes (PECs) by a simple and reproducible polyelectrolyte complexation method between low molecular mass dermatan sulfate (polyanionic polysaccharide) and chitosan (polycationic polysaccharide), and evaluated the cellular uptake by vascular endothelial cells. The composition and the composition homogeneity of PECs were confirmed by (13)C-CP-MAS spectroscopy and by polyacrylamide gel electrophoresis, respectively. The hydrodynamic radius, determined by dynamic light scattering, was 729±11nm. PECs were not cytotoxic for a murine heart endothelium-derived cell line. Fluorescent confocal microscopy showed the specific uptake of fluorescently-labeled PECs by endothelial cells when they were cultured alone or in the presence of macrophages. Overall, these findings confirmed the potential of these PECs for targeting different agents to the vessel wall in the prevention, diagnosis, and therapy of vascular disease.

  15. Microfabricated photocrosslinkable polyelectrolyte-complex of chitosan and methacrylated gellan gum

    PubMed Central

    Coutinho, Daniela F.; Sant, Shilpa; Shakiba, Mojdeh; Wang, Ben; Gomes, Manuela E.; Neves, Nuno M.; Reis, Rui L.

    2012-01-01

    Chitosan (CHT) based polyelectrolyte complexes (PECs) have been receiving great attention for tissue engineering approaches. These hydrogels are held together by ionic forces and can be disrupted by changes in physiological conditions. In this study, we present a new class of CHT-based PEC hydrogels amenable to stabilization by chemical crosslinking. The photocrosslinkable anionic methacrylated gellan gum (MeGG) was complexed with cationic CHT and exposed to light, forming a PEC hydrogel. The chemical characterization of the photocrosslinkable PEC hydrogel by Fourier transform infrared spectroscopy (FTIR) revealed absorption peaks specific to the raw polymers. A significantly higher swelling ratio was observed for the PEC hydrogel with higher CHT content. The molecular interactions between both polysaccharides were evaluated chemically and microscopically, indicating the diffusion of CHT to the interior of the hydrogel. We hypothesized that the addition of MeGG to CHT solution first leads to a membrane formation around MeGG. Then, migration of CHT inside the MeGG hydrogel occurs to balance the electrostatic charges. The photocrosslinkable feature of MeGG further allowed the formation of cell-laden microscale hydrogel units with different shapes and sizes. Overall, this system is potentially useful for a variety of applications including the replication of microscale features of tissues for modular tissue engineering. PMID:23293429

  16. Light harvesting proteins for solar fuel generation in bioengineered photoelectrochemical cells.

    PubMed

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used.

  17. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    PubMed

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1). PMID:27552431

  18. PERIOD ERROR ESTIMATION FOR THE KEPLER ECLIPSING BINARY CATALOG

    SciTech Connect

    Mighell, Kenneth J.; Plavchan, Peter

    2013-06-15

    The Kepler Eclipsing Binary Catalog (KEBC) describes 2165 eclipsing binaries identified in the 115 deg{sup 2} Kepler Field based on observations from Kepler quarters Q0, Q1, and Q2. The periods in the KEBC are given in units of days out to six decimal places but no period errors are provided. We present the PEC (Period Error Calculator) algorithm, which can be used to estimate the period errors of strictly periodic variables observed by the Kepler Mission. The PEC algorithm is based on propagation of error theory and assumes that observation of every light curve peak/minimum in a long time-series observation can be unambiguously identified. The PEC algorithm can be efficiently programmed using just a few lines of C computer language code. The PEC algorithm was used to develop a simple model that provides period error estimates for eclipsing binaries in the KEBC with periods less than 62.5 days: log {sigma}{sub P} Almost-Equal-To - 5.8908 + 1.4425(1 + log P), where P is the period of an eclipsing binary in the KEBC in units of days. KEBC systems with periods {>=}62.5 days have KEBC period errors of {approx}0.0144 days. Periods and period errors of seven eclipsing binary systems in the KEBC were measured using the NASA Exoplanet Archive Periodogram Service and compared to period errors estimated using the PEC algorithm.

  19. A novel, biodegradable and reversible polyelectrolyte platform for topical-colonic delivery of pentosan polysulphate.

    PubMed

    Shah, Hardik K; Conkie, Jim A; Tait, Robert C; Johnson, James R; Wilson, Clive G

    2011-02-14

    The goal of the present work was to develop a swellable hydrogel colonic delivery system, which would maximise the availability of the therapeutic agent at a site of inflammation, especially where the water is scarce. A novel method was developed to manufacture a biodegradable and reversible polyelectrolyte complex (PEC) containing chitosan and poly acrylic-acid (PAA). The PEC was analysed using FTIR and DSC, which confirmed the formation of non-permanent swollen gel-network at an alkaline pH. Pentosan polysulphate (PPS) was incorporated in a PEC and an activated partial thromboplastin time assay was developed to measure the release of PPS from PEC. In vitro studies suggested that the release of PPS was dependent on the initial drug loading and the composition of the PEC. The gel strength of the swollen network, determined using a texture analyser, was dependent on polymer composition and the amount of PPS incorporated. Bacterial enzymes were collected from the rat caecum and colon for the digestion studies and characterised for glucosidase activity, glucuronidase activity and protein content. The digestion of the reversible polyelectrolyte complexes was measured using a dinitro salicylic acid assay and an increased release of drug was also confirmed in the presence of bacterial enzymes.

  20. Light Harvesting Proteins for Solar Fuel Generation in Bioengineered Photoelectrochemical Cells

    PubMed Central

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used. PMID:24678669

  1. Simplified human model and pedestrian simulation in the millimeter-wave region

    NASA Astrophysics Data System (ADS)

    Han, Junghwan; Kim, Seok; Lee, Tae-Yun; Ka, Min-Ho

    2016-02-01

    The 24 GHz and 77 GHz radar sensors have been studied as a strong candidate for advanced driver assistance systems(ADAS) because of their all-weather capability and accurate range and radial velocity measuring scheme. However, developing a reliable pedestrian recognition system hasmany obstacles due to the inaccurate and non-trivial radar responses at these high frequencies and the many combinations of clothes and accessories. To overcome these obstacles, many researchers used electromagnetic (EM) simulation to characterize the radar scattering response of a human. However, human simulation takes so long time because of the electrically huge size of a human in the millimeter-wave region. To reduce simulation time, some researchers assumed the skin of a human is the perfect electric conductor (PEC) and have simulated the PEC human model using physical optics (PO) algorithm without a specific explanation about how the human body could be modeled with PEC. In this study, the validity of the assumption that the surface of the human body is considered PEC in the EM simulation is verified, and the simulation result of the dry skin human model is compared with that of the PEC human model.

  2. Role of Au(III) coordination by polymer in "green" synthesis of gold nanoparticles using chitosan derivatives.

    PubMed

    Pestov, Alexander; Nazirov, Alexander; Privar, Yuliya; Modin, Evgeny; Bratskaya, Svetlana

    2016-10-01

    Here we report "green" synthesis of gold nanoparticles in solutions of heterocyclic chitosan derivatives (N-(4-imidazolyl)methylchitosan (IMC), N-2-(2-pyridyl)ethylchitosan (2-PEC), and N-2-(4-pyridyl)ethylchitosan (4-PEC)) and show how efficiency of Au(III) binding to polymer influences the Au(III) reduction rate and the size of the gold nanoparticles formed using only the reducing power of these chitosan derivatives. Rheology measurements and (1)H NMR spectroscopy data have confirmed that cleavage of glycosidic bond is a common mechanism of reducing species generation in solutions of chitosan and its N-heterocyclic derivatives. However, the emerging additional reducing species in 2-PEC and 4-PEC solutions due to vinylpyridine elimination promotes Au(III) reduction and gold nanoparticles growth despite lower efficiency of glycosidic bond cleavage in pyridyl derivatives. The decrease of the average size of gold nanoparticles in the row chitosan>2-PEC>IMC supported assumption that the increase of ligand nucleophilicity and stability of Au(III)-polymer complex results in formation of smaller nanoparticles.

  3. Role of Au(III) coordination by polymer in "green" synthesis of gold nanoparticles using chitosan derivatives.

    PubMed

    Pestov, Alexander; Nazirov, Alexander; Privar, Yuliya; Modin, Evgeny; Bratskaya, Svetlana

    2016-10-01

    Here we report "green" synthesis of gold nanoparticles in solutions of heterocyclic chitosan derivatives (N-(4-imidazolyl)methylchitosan (IMC), N-2-(2-pyridyl)ethylchitosan (2-PEC), and N-2-(4-pyridyl)ethylchitosan (4-PEC)) and show how efficiency of Au(III) binding to polymer influences the Au(III) reduction rate and the size of the gold nanoparticles formed using only the reducing power of these chitosan derivatives. Rheology measurements and (1)H NMR spectroscopy data have confirmed that cleavage of glycosidic bond is a common mechanism of reducing species generation in solutions of chitosan and its N-heterocyclic derivatives. However, the emerging additional reducing species in 2-PEC and 4-PEC solutions due to vinylpyridine elimination promotes Au(III) reduction and gold nanoparticles growth despite lower efficiency of glycosidic bond cleavage in pyridyl derivatives. The decrease of the average size of gold nanoparticles in the row chitosan>2-PEC>IMC supported assumption that the increase of ligand nucleophilicity and stability of Au(III)-polymer complex results in formation of smaller nanoparticles. PMID:27259650

  4. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    PubMed

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1).

  5. Ceramide formation mediated by acid sphingomyelinase facilitates endosomal escape of caliciviruses.

    PubMed

    Shivanna, Vinay; Kim, Yunjeong; Chang, Kyeong-Ok

    2015-09-01

    Our recent results demonstrated that bile acids facilitate virus escape from the endosomes into the cytoplasm for successful replication of porcine enteric calicivirus (PEC). We report a novel finding that bile acids can be substituted by cold treatment for endosomal escape and virus replication. This endosomal escape by cold treatment or bile acids is associated with ceramide formation by acid sphingomyelinase (ASM). ASM catalyzes hydrolysis of sphingomyelin into ceramide, which is known to destabilize lipid bilayer. Treatment of LLC-PK cells with bile acids or cold led to ceramide formation, and small molecule antagonists or siRNA of ASM blocked ceramide formation in the endosomes and significantly reduced PEC replication. Inhibition of ASM resulted in the retention of PEC, feline calicivirus or murine norovirus in the endosomes in correlation with reduced viral replication. These results suggest the importance of viral escape from the endosomes for the replication of various caliciviruses. PMID:25985440

  6. Spin-Coated Polyelectrolyte Coacervate Films.

    PubMed

    Kelly, Kristopher D; Schlenoff, Joseph B

    2015-07-01

    Thin films of complexes made from oppositely charged polyelectrolytes have applications as supported membranes for separations, cell growth substrates, anticorrosion coatings, biocompatible coatings, and drug release media, among others. The relatively recent technique of layer-by-layer assembly reliably yields conformal coatings on substrates but is impractically slow for films with thickness greater than about 1 μm, even when accelerated many fold by spraying and/or spin assembly. In the present work, thin, uniform, smooth films of a polyelectrolyte complex (PEC) are rapidly made by spin-coating a polyelectrolyte coacervate, a strongly hydrated viscoelastic liquidlike form of PEC, on a substrate. While the apparatus used to deposit the PEC film is conventional, the behavior of the coacervate, especially the response to salt concentration, is highly nontraditional. After glassification by immersion in water, spun-on films may be released from their substrates to yield free-standing membranes of thickness in the micrometer range.

  7. Supramolecular Systems Behavior at the Air-Water Interface. Molecular Dynamic Simulation Study.

    NASA Astrophysics Data System (ADS)

    Sandoval, C.; Saavedra, M.; Gargallo, L.; Radić, D.

    2008-08-01

    Atomistic molecular dynamics simulation (MDS) was development to investigate the structural and dynamic properties of a monolayer of supramolecular systems. The simulations were performed at room temperature, on inclusion complexes (ICs) of α-cyclodextrin (CD) with poly(ethylene-oxide)(PEO), poly(ɛ-caprolactone)(PEC) and poly(tetrahydrofuran)(PTHF). The simulations were carried out for a surface area of 30Å. The trajectories of the MDS show that the system more stable was IC-PEC, being the less stable IC-PEO. The disordered monolayer for the systems was proved by the orientation correlation function and the radial distribution function between the polar groups of ICs and the water molecules. We found that the system IC-PEC was more stable that the systems IC-PTHF and IC-PEO.

  8. Low-toxic Ag2S quantum dots for photoelectrochemical detection glucose and cancer cells.

    PubMed

    Zhang, Xiaoru; Liu, Mingshuai; Liu, Hongxia; Zhang, Shusheng

    2014-06-15

    A new photoelectrochemical (PEC) biosensor was developed using low-toxic Ag2S QDs as photoelectrochemically active species. Energy levels of Ag2S and Ag2Se QD were compared to explain their differences in the PEC performance. The preparation condition of Ag2S QD was optimized and its structure characterization was measured. Then the developed photoelectric active interface was used to detect glucose and MCF-7 cancer cell and showed the good sensitivity and specificity. Under optimal condition, detection limits of 3.2 × 10(-5)M for glucose and 98 cells/mL for MCF-7 cell were achieved. Thus, the prepared Ag2S QD could serve as an excellent and promising photoelectric active material in the PEC biosensor.

  9. Finite element modeling of wall-loss sizing in a steam generator tube using a pulsed eddy current probe

    NASA Astrophysics Data System (ADS)

    Babbar, V. K.; Lepine, B.; Buck, J.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2015-03-01

    Inspection of steam generator (SG) tubes by conventional eddy current may, in general, involve analysis of indications from volumetric wall loss, cracks, fouling and support-plate degradation; however, it may be difficult to size or quantify effects from support-to-tube gap and tube tilt, especially in the presence of support plates. Pulsed eddy current (PEC) technology is being developed to investigate such complex tube and flaw geometries. The present work employs finite element modeling to investigate the effectiveness of PEC in identifying and sizing the outer diameter wall-loss in SG tubes. The signals analyzed using a modified principal components analysis (PCA) method reveal the potential success of a PEC-PCA combination to produce scores that can be used to size the wall-loss in the presence of support plates. The modeling results are in good agreement with experimental observations.

  10. Photoelectrochemical detection of metal ions.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-07-21

    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  11. Mg-Zr Cosubstituted Ta3N5 Photoanode for Lower-Onset-Potential Solar-Driven Photoelectrochemical Water Splitting.

    PubMed

    Seo, Jeongsuk; Takata, Tsuyoshi; Nakabayashi, Mamiko; Hisatomi, Takashi; Shibata, Naoya; Minegishi, Tsutomu; Domen, Kazunari

    2015-10-14

    In p/n photoelectrochemical (PEC) cell systems, a low onset potential for the photoanode, as well as a high photocurrent, are critical for efficient water splitting. Here, we report a Mg-Zr cosubstituted Ta3N5 (Ta3N5:Mg+Zr) photoanode, designed to provide a more negative onset potential for PEC water splitting. The anodic photocurrent onset on Ta3N5:Mg+Zr was 0.55 V(RHE) under AM 1.5G-simulated sunlight, which represented a negative shift from the ca. 0.8 V(RHE) for pure Ta3N5. This negative shift in the onset potential of PEC water splitting was attributed to the change in the bandgap potential due to partial substitution by the foreign ions Mg(2+) and/or Zr(4+). PMID:26426439

  12. Classical and Mexican hat-type potential energy curve for the hydrogen molecule from a confined Kratzer oscillator

    NASA Astrophysics Data System (ADS)

    van Hooydonk, G.

    2016-03-01

    We review harmonic oscillator theory for closed, stable quantum systems. The H2 potential energy curve (PEC) of Mexican hat-type, calculated with a confined Kratzer oscillator, is better than the Rydberg-Klein-Rees (RKR) H2 PEC. Compared with QM, the theory of chemical bonding is simplified, since a confined Kratzer oscillator can also lead to the long sought for universal function, once called the Holy Grail of Molecular Spectroscopy. This is validated by reducing PECs for different bonds H2, HF, I2, N2 and O2 to a single one. The equal probability for H2, originating either from HA + HB or HB + HA, is quantified with a Gauss probability density function. At the Bohr scale, a confined harmonic oscillator behaves properly at the extremes of bound two-nucleon quantum systems.

  13. Dual Oxygen and Tungsten Vacancies on a WO3 Photoanode for Enhanced Water Oxidation.

    PubMed

    Ma, Ming; Zhang, Kan; Li, Ping; Jung, Myung Sun; Jeong, Myung Jin; Park, Jong Hyeok

    2016-09-19

    Alleviating charge recombination at the electrode/electrolyte interface by introducing an overlayer is considered an efficient approach to improve photoelectrochemical (PEC) water oxidation. A WO3 overlayer with dual oxygen and tungsten vacancies was prepared by using a solution-based reducing agent, LEDA (lithium dissolved in ethylenediamine), which improved the PEC performance of the mesoporous WO3 photoanode dramatically. In comparison to the pristine samples, the interconnected WO3 nanoparticles surrounded by a 2-2.5 nm thick overlayer exhibited a photocurrent density approximately 2.4 times higher and a marked cathodic shift of the onset potential, which is mainly attributed to the facilitative effect on interface charge transfer and the improved conductivity by enhanced charge carrier density. This simple and effective strategy may provide a new path to improve the PEC performance of other photoanodes. PMID:27533279

  14. Assembling Supramolecular Dye-Sensitized Photoelectrochemical Cells for Water Splitting.

    PubMed

    Ding, Xin; Gao, Yan; Ye, Lu; Zhang, Linlin; Sun, Licheng

    2015-12-01

    The method used to assemble dye-sensitized photoelectrochemical (DS-PEC) devices plays a vital role in determining its photoactivity and stability. We report a simple and effective method to assemble supramolecular DS-PECs introducing PMMA as support material and a catalyst modified with long carbon chains as photoanodes. The long carbon chains in combination with PMMA allow to better immobilize the catalyst. DS-PECs obtained by this simple method have display excellent photoactivities and stabilities. A photocurrent density of 1.1 mA cm(-2) and a maximum IPCE of 9.5 % have been obtained with a 0.2 V vs NHE external bias.

  15. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting

    NASA Astrophysics Data System (ADS)

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-01

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p–n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance.

  16. An auxiliary-field quantum Monte Carlo study of the chromium dimer

    SciTech Connect

    Purwanto, Wirawan Zhang, Shiwei; Krakauer, Henry

    2015-02-14

    The chromium dimer (Cr{sub 2}) presents an outstanding challenge for many-body electronic structure methods. Its complicated nature of binding, with a formal sextuple bond and an unusual potential energy curve (PEC), is emblematic of the competing tendencies and delicate balance found in many strongly correlated materials. We present an accurate calculation of the PEC and ground state properties of Cr{sub 2}, using the auxiliary-field quantum Monte Carlo (AFQMC) method. Unconstrained, exact AFQMC calculations are first carried out for a medium-sized but realistic basis set. Elimination of the remaining finite-basis errors and extrapolation to the complete basis set limit are then achieved with a combination of phaseless and exact AFQMC calculations. Final results for the PEC and spectroscopic constants are in excellent agreement with experiment.

  17. Photoelectrochemical, impedance and optical data for self Sn-diffusion doped Fe2O3 photoanodes fabricated at high temperature by one and two-step annealing methods

    PubMed Central

    Shinde, Pravin S.; Annamalai, Alagappan; Kim, Ju Hun; Choi, Sun Hee; Lee, Jae Sung; Jang, Jum Suk

    2015-01-01

    The optical, morphological and photoelectrochemical (PEC) properties of transition metal oxide semiconductors are important to understand their influence on water oxidation performance. Herein, we provide experimental evidences for a better understanding of the factors that dictate the interactions of Sn-diffusion doping on the PEC properties of Fe2O3 photoanodes fabricated at high temperature by one- and two-step annealing methods. The synthesis, characterization methods and other experimental details are provided. Limited previous information on the PEC and electrochemical impedance spectroscopic studies has been published. This data article contains Supplementary data, figures and methods related to the research article by Shinde et al. (2015) [1]. Here, we provide a further set of the obtained experimental data results. PMID:26693514

  18. Zero photoelastic and water durable ZnO–SnO–P{sub 2}O{sub 5}–B{sub 2}O{sub 3} glasses

    SciTech Connect

    Saitoh, Akira; Nakata, Kohei; Yamamoto, Naoki; Takebe, Hiromichi; Tricot, Grégory; Chen, Yuanyuan

    2015-04-01

    We report properties of zero birefringent xZnO–(67–x)SnO–(33–y)P{sub 2}O{sub 5}–y B{sub 2}O{sub 3} glasses, within 18.5 ≤ x ≤ 22 and y = 0, 3, and 10 mol. %. These compositions of boro-phosphate glasses provide both zero photoelastic constant (PEC) and improved water durability. x = 19 and y = 3 compositions show minimum PEC of −0.002 × 10{sup −12} Pa{sup −1}, which can contribute to candidate material for fiber current sensor devise without lead. The structures of zero photoelastic glasses were investigated by Raman scattering and nuclear magnetic resonance spectroscopies. Compositions of zero PEC glasses are explained by the empirical model proposed by Zwanziger et al. [Chem. Mater. 19, 286-290 (2007)].

  19. Application of Model Based Parameter Estimation for RCS Frequency Response Calculations Using Method of Moments

    NASA Technical Reports Server (NTRS)

    Reddy, C. J.

    1998-01-01

    An implementation of the Model Based Parameter Estimation (MBPE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFTE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current is expanded in a rational function and the coefficients of the rational function are obtained using the frequency derivatives of the EFIE. Using the rational function, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. Good agreement between MBPE and the exact solution over the bandwidth is observed.

  20. SUPRAMOLECULAR SYSTEMS BEHAVIOR AT THE AIR-WATER INTERFACE. MOLECULAR DYNAMIC SIMULATION STUDY

    SciTech Connect

    Sandoval, C.; Saavedra, M.; Gargallo, L.; Radic, D.

    2008-08-28

    Atomistic molecular dynamics simulation (MDS) was development to investigate the structural and dynamic properties of a monolayer of supramolecular systems. The simulations were performed at room temperature, on inclusion complexes (ICs) of {alpha}-cyclodextrin (CD) with poly(ethylene-oxide)(PEO), poly({epsilon}-caprolactone)(PEC) and poly(tetrahydrofuran)(PTHF). The simulations were carried out for a surface area of 30A ring . The trajectories of the MDS show that the system more stable was IC-PEC, being the less stable IC-PEO. The disordered monolayer for the systems was proved by the orientation correlation function and the radial distribution function between the polar groups of ICs and the water molecules. We found that the system IC-PEC was more stable that the systems IC-PTHF and IC-PEO.

  1. Influence of pH on the quantum-size-controlled photoelectrochemical etching of epitaxial InGaN quantum dots

    DOE PAGESBeta

    Xiao, Xiaoyin; Lu, Ping; Fischer, Arthur J.; Coltrin, Michael E.; Wang, George T.; Koleske, Daniel D.; Tsao, Jeffrey Y.

    2015-11-18

    Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In2O3 and/or Ga2O3) form which interfere with quantum dot formation. Furthermore, at pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.

  2. Photoelectrocatalytic degradation of triclosan on TiO2 nanotube arrays and toxicity change.

    PubMed

    Liu, Haijin; Cao, Xianglin; Liu, Guoguang; Wang, Yingling; Zhang, Nan; Li, Tong; Tough, Robert

    2013-09-01

    Triclosan, one of the most widely used disinfectants, has been found to be toxic to animals and human beings. In this paper, triclosan was degraded on TiO2 nanotube arrays, using a photoelectrocatalytic (PEC) process under UV illumination, with Na2SO4 as the supporting electrolyte. The effect of bias potential was investigated and the results showed that 0V was the most appropriate potential for the degradation of triclosan. In 30min, 78.7% of triclosan had degraded during the PEC process. Intermediate analysis showed that 2,7-dichlorodibenzodioxin (DCDD) had formed during the degradation. The toxicity change during the PEC process was investigated using a luminescent bacteria test, with the results demonstrating that the toxicity of the reaction liquid decreased at the beginning and subsequently increased to a stable level. The indications were that some intermediates such as 2,7-dichlorodibenzodioxin was more toxic and stable than triclosan in the solution.

  3. Accurate potential energy curve of the LiH{sup +} molecule calculated with explicitly correlated Gaussian functions

    SciTech Connect

    Tung, Wei-Cheng; Adamowicz, Ludwik

    2014-03-28

    Very accurate calculations of the ground-state potential energy curve (PEC) of the LiH{sup +} ion performed with all-electron explicitly correlated Gaussian functions with shifted centers are presented. The variational method is employed. The calculations involve optimization of nonlinear exponential parameters of the Gaussians performed with the aid of the analytical first derivatives of the energy determined with respect to the parameters. The diagonal adiabatic correction is also calculated for each PEC point. The PEC is then used to calculate the vibrational energies of the system. In that calculation, the non-adiabatic effects are accounted for by using an effective vibrational mass obtained by the minimization of the difference between the vibrational energies obtained from the calculations where the Born-Oppenheimer approximation was not assumed and the results of the present calculations.

  4. Design and specification of a centralized manufacturing data management and scheduling system

    NASA Technical Reports Server (NTRS)

    Farrington, Phillip A.

    1993-01-01

    As was revealed in a previous study, the Materials and Processes Laboratory's Productivity Enhancement Complex (PEC) has a number of automated production areas/cells that are not effectively integrated, limiting the ability of users to readily share data. The recent decision to utilize the PEC for the fabrication of flight hardware has focused new attention on the problem and brought to light the need for an integrated data management and scheduling system. This report addresses this need by developing preliminary designs specifications for a centralized manufacturing data management and scheduling system for managing flight hardware fabrication in the PEC. This prototype system will be developed under the auspices of the Integrated Engineering Environment (IEE) Oversight team and the IEE Committee. At their recommendation the system specifications were based on the fabrication requirements of the AXAF-S Optical Bench.

  5. In situ enzymatic ascorbic acid production as electron donor for CdS quantum dots equipped TiO2 nanotubes: a general and efficient approach for new photoelectrochemical immunoassay.

    PubMed

    Zhao, Wei-Wei; Ma, Zheng-Yuan; Yan, Dong-Yang; Xu, Jing-Juan; Chen, Hong-Yuan

    2012-12-18

    In this work, a novel photoelectrochemical (PEC) immunoanalysis format was developed for sensitive and specific detection of prostate-specific antigen (PSA) based on an in situ electron donor producing approach. Thioglycolic acid-capped CdS quantum dots (QDs) equipped TiO(2) nanotubes (NTs) were fabricated via a facile electrostatic adsorption method. The coupling of CdS QDs and TiO(2) NTs results in an enhanced excitation and photo-to-electric conversion efficiency. Using alkaline phosphatase catalytic chemistry to in situ generate ascorbic acid for electron donating, an exquisite immunosandwich protocol was successfully constructed for the PSA assay due to the dependence of the photocurrent signal on the concentration of electron donor. This work opens a different perspective for transducer design in PEC detection and provides a general format for future development of PEC immunoanalysis.

  6. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting

    NASA Astrophysics Data System (ADS)

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-01

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p-n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance.

  7. Modeling practical performance limits of photoelectrochemical water splitting based on the current state of materials research.

    PubMed

    Seitz, Linsey C; Chen, Zhebo; Forman, Arnold J; Pinaud, Blaise A; Benck, Jesse D; Jaramillo, Thomas F

    2014-05-01

    Photoelectrochemical (PEC) water splitting is a means to store solar energy in the form of hydrogen. Knowledge of practical limits for this process can help researchers assess their technology and guide future directions. We develop a model to quantify loss mechanisms in PEC water splitting based on the current state of materials research and calculate maximum solar-to-hydrogen (STH) conversion efficiencies along with associated optimal absorber band gaps. Various absorber configurations are modeled considering the major loss mechanisms in PEC devices. Quantitative sensitivity analyses for each loss mechanism and each absorber configuration show a profound impact of both on the resulting STH efficiencies, which can reach upwards of 25 % for the highest performance materials in a dual stacked configuration. Higher efficiencies could be reached as improved materials are developed. The results of the modeling also identify and quantify approaches that can improve system performance when working with imperfect materials.

  8. Interplay of light transmission and catalytic exchange current in photoelectrochemical systems

    SciTech Connect

    Fountaine, Katherine T.; Lewerenz, Hans J.; Atwater, Harry A.

    2014-10-27

    We develop an analytic current-voltage expression for a variable junction photoelectrochemical (PEC) cell and use it to investigate and illustrate the influence of the optical and electrical properties of catalysts on the optoelectronic performance of PEC devices. Specifically, the model enables a simple, yet accurate accounting of nanostructured catalyst optical and electrical properties through incorporation of an optical transmission factor and active catalytic area factor. We demonstrate the utility of this model via the output power characteristics of an exemplary dual tandem solar cell with indium gallium phosphide and indium gallium arsenide absorbers with varying rhodium catalyst nanoparticle loading. The approach highlights the importance of considering interactions between independently optimized components for optimal PEC device design.

  9. Effect of N-acetylchito-oligosaccharides on activation of phagocytes.

    PubMed

    Suzuki, K; Tokoro, A; Okawa, Y; Suzuki, S; Suzuki, M

    1986-01-01

    Four N-acetylchito-oligosaccharides, from tetra-N-acetylchitotetraose (NACOS-4) to hepta-N-acetylchitoheptaose (NACOS-7), were found to increase the number of peritoneal exudate cells (PEC) in male BALB/c mice after 3 hr intraperitoneal administration of 50 mg/kg of each oligosaccharide. The number of attracted cells, consisting largely of polymorphonuclear leukocytes (PMN), was proportional to the molecular weights of the administered oligosaccharides, except for NACOS-7 which displayed the same activity as NACOS-6. In an in vitro chemotaxis assay using normal mouse leukocytes, it was found that NACOS-6 displayed stronger effects than muramyl dipeptide. The PEC from NACOS-6 treated mice showed a higher active oxygen-generating activity. PMN from normal mouse peripheral blood were also shown to have enhanced active oxygen-generating activity in vitro. PEC from NACOS-6 treated mice were shown to possess strong candidacidal activity in vitro.

  10. Influence of pH on the quantum-size-controlled photoelectrochemical etching of epitaxial InGaN quantum dots

    SciTech Connect

    Xiao, Xiaoyin; Lu, Ping; Fischer, Arthur J.; Coltrin, Michael E.; Wang, George T.; Koleske, Daniel D.; Tsao, Jeffrey Y.

    2015-11-18

    Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In2O3 and/or Ga2O3) form which interfere with quantum dot formation. Furthermore, at pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.

  11. Characteristics of Planar Monopole Antenna on High Impedance Electromagnetic Surface

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Jastram, Nathan; Ponchak, George E.; Franklin, Rhonda R.

    2011-01-01

    This paper presents for the first time measured characteristics of a planar monopole antenna placed directly on a high impedance electromagnetic surface or artificial magnetic conductor (AMC). The return loss and radiation patterns are compared between the antenna in free space, and when placed directly on a perfect electrical conductor (PEC), and on the AMC. The antenna measured in free space has a wide pass band from 3 to 10 GHz. The return loss for the antenna on the PEC is nearly all reflected back and the return loss for the antenna on the AMC has a 10 dB bandwidth from 7.5 to 9.5 GHz. The gain of the antenna in free space, on PEC and on AMC is 1, -12 and 10 dBi, respectively. This indicates that the AMC is working properly, sending all the radiation outward with little loss.

  12. Application of AWE for RCS Frequency Response Calculations Using Method of Moments

    NASA Technical Reports Server (NTRS)

    Reddy, C. J.; Deshpande, M. D.

    1996-01-01

    An implementation of the Asymptotic Waveform Evaluation (AWE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFIE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current, thus obtained, is expanded in a Taylor series around the frequency of interest. The coefficients of the Taylor series (called 'moments') are obtained using the frequency derivatives of the EFIE. Using the moments, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. A good agreement between AWE and the exact solution over the bandwidth is observed.

  13. MRCI study of spectroscopic and molecular properties of X2Πg, a 4Πu, A2Πu, b 4 ? , D2Δg and B2 ? electronic states of ? ion

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoniu; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2011-06-01

    The potential energy curves (PECs) of six low-lying electronic states (X2Πg, a 4Πu, A2Πu, b 4 ? , D2Δg and B2 ? ) of ? ion were studied by the ab initio quantum chemical method. The calculations were carried out with the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with large correlation-consistent basis sets. Effects on the PECs of the core-valence correlation and relativistic corrections are taken into account. The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian (DKH2) approximation. The core-valence correlation correction is carried out with the cc-pCVQZ basis set, and the relativistic correction is performed at the level of cc-pVQZ basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI + Q). These PECs are extrapolated to the complete basis set (CBS) limit by the two-point total-energy extrapolation scheme. With these PECs, the spectroscopic parameters (Te , De , D 0, Re , ωe , ωexe , αe and Be ) are determined and compared with those reported in the literature. The conclusion can be reached that the effect on the spectroscopic parameters of the core-valence correlation correction is larger than that of the relativistic correction. With the PECs obtained by the MRCI + Q/CV+DK+56 calculations, the vibrational levels and inertial rotation constants of the first 26 vibrational states are determined for these electronic states of non-rotating ? ion. Comparison with the experimental data shows that the present spectroscopic parameters and molecular constants are accurate.

  14. Matrix metalloproteinase-9 expression is enhanced in renal parietal epithelial cells of zucker diabetic Fatty rats and is induced by albumin in in vitro primary parietal cell culture.

    PubMed

    Zhang, Yuanyuan; George, Jasmine; Li, Yun; Olufade, Rebecca; Zhao, Xueying

    2015-01-01

    As a subfamily of matrix metalloproteinases (MMPs), gelatinases including MMP-2 and MMP-9 play an important role in remodeling and homeostasis of the extracellular matrix. However, conflicting results have been reported regarding their expression level and activity in the diabetic kidney. This study investigated whether and how MMP-9 expression and activity were changed in glomerular epithelial cells upon albumin overload. In situ zymography, immunostaining and Western blot for renal MMP gelatinolytic activity and MMP-9 protein expression were performed in Zucker lean and Zucker diabetic rats. Confocal microscopy revealed a focal increase in gelatinase activity and MMP-9 protein in the glomeruli of diabetic rats. Increased glomerular MMP-9 staining was mainly observed in hyperplastic parietal epithelial cells (PECs) expressing claudin-1 in the diabetic kidneys. Interestingly, increased parietal MMP-9 was often accompanied by decreased staining for podocyte markers (nephrin and podocalyxin) in the sclerotic area of affected glomeruli in diabetic rats. Additionally, urinary excretion of podocyte marker proteins was significantly increased in association with the levels of MMP-9 and albumin in the urine of diabetic animals. To evaluate the direct effect of albumin on expression and activity of MMP-9, primary cultured rat glomerular PECs were incubated with rat serum albumin (0.25 - 1 mg/ml) for 24 - 48 hrs. MMP-9 mRNA levels were significantly increased following albumin treatment. Meanwhile, albumin administration resulted in a dose-dependent increase in MMP-9 protein and activity in culture supernatants of PECs. Moreover, albumin activated p44/42 mitogen-activated protein kinase (MAPK) in PECs. Inhibition of p44/42 MAPK suppressed albumin-induced MMP-9 secretion from glomerular PECs. Taken together, we have demonstrated that an up-regulation of MMP-9 in activated parietal epithelium is associated with a loss of adjacent podocytes in progressive diabetic nephropathy

  15. Sequential appearance of gamma/delta- and alpha/beta-bearing T cells in the peritoneal cavity during an i.p. infection with Listeria monocytogenes.

    PubMed

    Ohga, S; Yoshikai, Y; Takeda, Y; Hiromatsu, K; Nomoto, K

    1990-03-01

    To search for a potential role of T cell antigen receptor (TcR) gamma/delta-bearing cells in host-defense against Listeria monocytogenes, we analyzed the sequential appearance of gamma/delta and alpha/beta T cell in the peritoneal exudate cells (PEC) during an i.p. infection with sublethal dose (2 X 10(3) of viable Listeria organisms in mice. The PEC on day 1 after the infection consisted of 48% macrophages and 50% lymphocytes, most of which were surface IgM+ (B) cells. The number of PEC increased to the maximal level by day 3. The PEC at this stage contained an appreciable number of CD3+ T cells in addition to a large number of macrophages. Of the CD3+ cells, the proportion of CD4- CD8- cells, most of which expressed no TcR alpha/beta, increased to the maximal level on day 3 after the infection. In correlation with an increased number of CD3+ CD4- CD8- TcR alpha/beta- cells, high level of TcR gamma/delta chain gene messages was detected in the nonadherent population of the PEC on this stage. On the other hand, the PEC on day 8 contained an increased number of CD4+ CD8- and CD4- CD8+ cells which expressed TcR alpha/beta chain on their surface. These results suggest that the gamma/delta T cells precede the alpha/beta T cells in appearance during listerial infection. The gamma/delta T cells may be involved at the first line of the host-defense against Listeria.

  16. Design and Characterization of Photoelectrodes from First Principles

    SciTech Connect

    Ogitsu, T; Wood, B; Choi, W; Huda, M; Wei, S

    2012-05-11

    Although significant performance improvements have been realized since the first demonstration of sunlight-driven water splitting in 1972, mainstream adoption of photoelectrochemical (PEC) cells remains limited by an absence of cost-effective electrodes that show simultaneously high conversion efficiency and good durability. Here we outline current and future efforts to use advanced theoretical techniques to guide the development of a durable, high-performance PEC electrode material. Working in close collaboration with experimental synthesis and characterization teams, we use a twofold approach focusing on: (1) rational design of novel high-performance electrode materials; and (2) characterization and optimization of the electrode-electrolyte interface.

  17. An evaluation of multiple-schedule variations to reduce high-rate requests in the picture exchange communication system.

    PubMed

    Landa, Robin; Hanley, Gregory P

    2016-06-01

    Using procedures similar to those of Tiger, Hanley, and Heal (2006), we compared two multiple-schedule variations (S+/S- and S+ only) to treat high-rate requests for edible items in the Picture Exchange Communication System (PECS). Two individuals with autism participated, after they showed persistent requests for edible items after PECS training. Stimulus control was achieved only with the multiple schedule that involved presentation of a discriminative stimulus during reinforcement components and its removal during extinction components (S+ only). Discriminated requests were maintained for the 1 participant who experienced schedule thinning. PMID:26814152

  18. Silicon nanostructures-induced photoelectrochemical solar water splitting for energy applications

    NASA Astrophysics Data System (ADS)

    Dadwal, U.; Ranjan, Neha; Singh, R.

    2016-05-01

    We study the photoelectrochemical (PEC) solar water splitting assisted with synthesized nanostructures. Si nanowires decorated with silver dendrite nanostructures have been synthesized using metal assisted wet chemical etching of (100) Si wafer. Etching has been carried out in an aqueous solution consisting of 5M HF and 0.02M AgNO3. Investigations showed that such type of semiconductor nanostructures act as efficient working electrodes for the splitting of normal water in PEC method. An enhancement in the photon-to-current conversion efficiency and solar-to-hydrogen evolution was observed for obtaining a practical source of clean and renewable fuel.

  19. PehN, a Polygalacturonase Homologue with a Low Hydrolase Activity, Is Coregulated with the Other Erwinia chrysanthemi Polygalacturonases

    PubMed Central

    Hugouvieux-Cotte-Pattat, Nicole; Shevchik, Vladimir E.; Nasser, William

    2002-01-01

    Erwinia chrysanthemi 3937 secretes an arsenal of pectinolytic enzymes, including at least eight endo-pectate lyases encoded by pel genes, which play a major role in the soft-rot disease caused by this bacterium on various plants. E. chrysanthemi also produces some hydrolases that cleave pectin. Three adjacent hydrolase genes, pehV, pehW, and pehX, encoding exo-poly-α-d-galacturonosidases, have been characterized. These enzymes liberate digalacturonides from the nonreducing end of pectin. We report the identification of a novel gene, named pehN, encoding a protein homologous to the glycosyl hydrolases of family 28, which includes mainly polygalacturonases. PehN has a low hydrolase activity on polygalacturonate and on various pectins. PehN action favors the activity of the secreted endo-pectate lyases, mainly PelB and PelC, and that of the periplasmic exo-pectate lyase PelX. However, removal of the pehN gene does not significantly alter the virulence of E. chrysanthemi. Regulation of pehN transcription was analyzed by using gene fusions. Like other pectinase genes, pehN transcription is dependent on several environmental conditions. It is induced by pectic catabolic products and is affected by growth phase, catabolite repression, osmolarity, anaerobiosis, nitrogen starvation, and the presence of calcium ions. The transcription of pehN is modulated by the repressor KdgR, which controls almost all the steps of pectin catabolism, and by cyclic AMP receptor protein (CRP), the global activator of sugar catabolism. The regulator PecS, which represses the transcription of the pel genes but activates that of pehV, pehW, and pehX, also activates transcription of pehN. The three regulators KdgR, PecS, and CRP act by direct interaction with the pehN promoter region. The sequences involved in the binding of these three regulators and of RNA polymerase have been precisely defined. Analysis of the simultaneous binding of these proteins indicates that CRP and RNA polymerase bind

  20. [Photoelectrocatalytic degradation of Rhodamine B using mesh Ti/TiO2 electrode].

    PubMed

    Liu, Huiling; Zhou, Ding; Li, Xiangzhong; Yue, Bingtao

    2002-07-01

    An innovative mesh titanium dioxide (TiO2) electrode was prepared by anodisation. The morphology and the crystalline texture of the TiO2 film on electrode were examined by SEM and Raman spectroscopy respectively. The results indicated that the structure and properties of the film depended on anodisation rate, and the anatase was the dominant component under the controlled experimental conditions. Biasing could increase the efficiency of photocatalytic degradation of organic matters. Mineralization Rhodamine B (Rh B) was complete relatively in photoelectro-catalytic (PEC) oxidation. Both chromogen destruction of Rh B and de-ehtylation in PEC degradation took place simultaneously.

  1. Teaching children with autism to engage in peer-directed mands using a picture exchange communication system.

    PubMed

    Paden, Amber R; Kodak, Tiffany; Fisher, Wayne W; Gawley-Bullington, Elizabeth M; Bouxsein, Kelly J

    2012-01-01

    We evaluated differential reinforcement of alternative behavior (DRA) plus prompting to increase peer-directed mands for preferred items using a picture exchange communication system (PECS). Two nonvocal individuals with autism participated. Independent mands with a peer increased with the implementation of DRA plus prompting for both participants. In addition, peers engaged in brief social interactions following the majority of mands for leisure items. These results suggest that teaching children to use PECS with peers may be one way to increase manding and social interactions in individuals with limited or no vocal repertoire.

  2. A Simple Photoelectrochemical Cell Using Fe+++/Fe++(aq) As Redox Couple

    NASA Astrophysics Data System (ADS)

    Saxena, Vibha; Koiry, S. P.; Veerender, P.; Vasundhara, Aswal, D. K.; Gupta, S. K.; Shivran, Neelam; Mula, S.; Chattopadhyay, S.; Yakhmi, J. V.

    2010-12-01

    We report a simple photoelectrochemical cell (PEC) using a derivative of borondipyrromethane (BODIPY), that is, (4,4-difluoro-1,3,5,7,8-pentamethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indecene) as dye sensitizer and an aqueous electrolyte containing Ferric/ferrous redox couple (F+++/Fe++). Under white light illumination of intensity ˜1 mW/cm2, the open circuit voltage and short-circuit current of the PEC was found to be respectively, 180 mV and 1.3 μA/cm2.

  3. First multi-epitope subunit vaccine against extraintestinal pathogenic Escherichia coli delivered by a bacterial type-3 secretion system (T3SS).

    PubMed

    Wieser, Andreas; Magistro, Giuseppe; Nörenberg, Dominik; Hoffmann, Christiane; Schubert, Sören

    2012-01-01

    Infections due to extraintestinal pathogenic E. coli (ExPEC) are very common in humans as well as in animals. In humans ExPEC infections include urinary tract infections (UTI), septicemia, and wound infections, which result in significant morbidity, mortality, and substantial healthcare costs. In view of the increasing number of ExPEC infections caused by more and more resistant strains, effective prevention would be desirable. Given the rising treatment costs, a vaccine may be cost-effective in selected patient groups, such as women with recurrent UTI, patients with neurologic disorders impairing bladder function and men with prostate hyperplasia. Previous vaccine studies used single target proteins or whole inactivated ExPEC cells. Here, we describe a vaccine system for oral application based on artificial multiple subunit vaccine proteins. Those multi-epitope proteins are composed of predicted epitopes derived from ExPEC virulence-associated proteins. As ExPEC are known to form intracellular biofilms in the urothelium and can also resist killing by non-activated macrophages, T-cell responses are supposed to be an important measure to counteract these stages of ExPEC during infection. Therefore, a live bacterial antigen delivery system based upon the Salmonella type-III secretion system (T3SS) was used in this study to directly deliver the vaccine proteins into the cytoplasm of the host cells. Epitope-rich domains of the proteins FyuA, IroN, ChuA, IreA, Iha, and Usp were expressed in an attenuated Salmonella enterica serovar Typhimurium strain and translocated into target cells for extended periods of time inducing a strong T-cell response. No significant antibody titre increase against the secreted vaccine proteins could be detected in vaginal wash or serum. Despite that, one of the vaccine proteins was able to significantly reduce bacterial load in the challenge model of intraperitoneal sepsis. This study shows that a vaccine encompassing distinct epitopes of

  4. Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

    SciTech Connect

    Cho, Seungho; Jang, Ji-Wook; Lee, Kun-Hong E-mail: ce20047@postech.ac.kr; Lee, Jae Sung E-mail: ce20047@postech.ac.kr

    2014-01-01

    Photoelectrochemical (PEC) water splitting to hydrogen is an attractive method for capturing and storing the solar energy in the form of chemical energy. Metal oxides are promising photoanode materials due to their low-cost synthetic routes and higher stability than other semiconductors. In this paper, we provide an overview of recent efforts to improve PEC efficiencies via applying a variety of fabrication strategies to metal oxide photoanodes including (i) size and morphology-control, (ii) metal oxide heterostructuring, (iii) dopant incorporation, (iv) attachments of quantum dots as sensitizer, (v) attachments of plasmonic metal nanoparticles, and (vi) co-catalyst coupling. Each strategy highlights the underlying principles and mechanisms for the performance enhancements.

  5. Comparative study of protective effects of chitin, chitosan, and N-acetyl chitohexaose against Pseudomonas aeruginosa and Listeria monocytogenes infections in mice.

    PubMed

    Okawa, Yoshio; Kobayashi, Makiko; Suzuki, Shigeo; Suzuki, Masuko

    2003-06-01

    We conducted a comparative study of the protective effects of chitin, chitosan, and N-acetyl chitohexaose (NACOS-6) against mice infected intravenously or intraperitoneally with Pseudomonas aeruginosa and Listeria monocytogenes. Mice pretreated with chitin, chitosan, and NACOS-6 showed resistance to intraperitoneal infections by both microbes. Only mice pretreated with chitin and chitosan showed resistance to intravenous infections by both microbes. The number, active oxygen generation, and myeloperoxidase activity of peritoneal exudate cells (PEC) in the chitin, chitosan, and NACOS-6-treated mice were greater than those of the untreated mice. Also, these PEC factors from mice pretreated with chitin and chitosan were greater than those from the NACOS-6-treated mice.

  6. Electromagnetic Enhancement of Pulsed Eddy Current Signals

    NASA Astrophysics Data System (ADS)

    Mandache, Catalin V.; Vivier Lefebvre, J. H.

    2007-03-01

    The sensitivity of pulsed eddy current (PEC) testing is increased when a layer of magnetic material is placed on the far side of the conductive test piece. This procedure ensures preservation of the lift-off point of intersection (LOI) feature, otherwise non-existent for the PEC inspections of magnetic materials. The presented method could find applications in non-destructive inspections for corrosion thinning, thickness measurement of conductive coatings over ferrous substrates, and integrity of thermally insulated pipes. Laboratory-obtained examples are given to support the method applicability.

  7. Exposure of WO3 Photoanodes to Ultraviolet Light Enhances Photoelectrochemical Water Oxidation.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-09-28

    Exposure of WO3 photoanodes to sustained irradiation by ultraviolet (UV) light induces a morphology change that enhances the photoelectrochemical (PEC) activity towards the oxygen evolution reaction (OER). A 30% enhancement in photocurrent density at 1.23 V vs RHE was measured despite a nominal change in onset potential. A structural and electrochemical analysis of the films before and after exposure to UV irradiation indicates that a higher film porosity and correspondingly higher specific surface area is responsible for the enhancement in PEC activity. The effect of prolonged UV irradiation on the WO3 films is fundamentally different to that which was previously observed for BiVO4 films.

  8. Exposure of WO3 Photoanodes to Ultraviolet Light Enhances Photoelectrochemical Water Oxidation.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-09-28

    Exposure of WO3 photoanodes to sustained irradiation by ultraviolet (UV) light induces a morphology change that enhances the photoelectrochemical (PEC) activity towards the oxygen evolution reaction (OER). A 30% enhancement in photocurrent density at 1.23 V vs RHE was measured despite a nominal change in onset potential. A structural and electrochemical analysis of the films before and after exposure to UV irradiation indicates that a higher film porosity and correspondingly higher specific surface area is responsible for the enhancement in PEC activity. The effect of prolonged UV irradiation on the WO3 films is fundamentally different to that which was previously observed for BiVO4 films. PMID:27644107

  9. Predicting concentrations of cytostatic drugs in sewage effluents and surface waters of Catalonia (NE Spain).

    PubMed

    Franquet-Griell, Helena; Gómez-Canela, Cristian; Ventura, Francesc; Lacorte, Silvia

    2015-04-01

    Cytostatic drugs, used in chemotherapy, are excreted unchanged by urine and feces or modified as metabolites. Elimination of these drugs in wastewater treatment plants (WWTPs) is often incomplete and residues reach surface water. Their presence in the natural environment depends on consumption patterns, excretion fraction and the effectiveness of the wastewater treatment. This study compiled the total consumption of cytostatic drugs in Catalonia (NE Spain) and provides data on the occurrence and risk of anticancer drugs in the aquatic environment by calculating predicted environmental concentrations (PECs). PECs were estimated using publicly available consumption data in the period of 2010-2012, published or calculated excretion values and wastewater elimination rates for a suite of 132 compounds. This allows predicting the range of concentrations in effluent wastewaters and receiving waters. Out of the 132 cytostatics, mycophenolic acid and hydroxycarbamide had a PEC value higher than 10ngL(-1). PECs were compared with MECs (measured environmental concentrations) to evaluate the reliability of the estimation. A risk assessment was conducted to determine the potential adverse effects of cytostatics in the environment. All the risk quotients calculated using EC50 in Daphnia magna were below 1, showing no significant risk.

  10. Using the Teaching and Guidance Policy Essentials Checklist to Build and Support Effective Early Childhood Systems

    ERIC Educational Resources Information Center

    Garrity, Sarah M.; Longstreth, Sascha L.; Salcedo-Potter, Nina S.; Staub, April

    2016-01-01

    The prevalence of preschool expulsion, coupled with racial disparities in expulsion rates and the potential long term negative effects of challenging behaviors in the early years, has created an urgent need to build early childhood systems to address these issues. The teaching and guidance policy essentials checklist (TAG-PEC) has been developed…

  11. From Theory of Work Adjustment to Person-Environment Correspondence Counseling: Vocational Psychology as Positive Psychology

    ERIC Educational Resources Information Center

    Eggerth, Donald E.

    2008-01-01

    This article argues that vocational psychology is, and has been, positive psychology. It provides an overview of the theory of work adjustment (TWA), one of the most robust and best validated theories in vocational psychology. It also provides an introduction to person-environment-correspondence (PEC) counseling, an extension of the TWA concepts…

  12. The phenotypes of podocytes and parietal epithelial cells may overlap in diabetic nephropathy

    PubMed Central

    Andeen, Nicole K.; Nguyen, Tri Q.; Steegh, Floor; Hudkins, Kelly L.; Najafian, Behzad; Alpers, Charles E.

    2015-01-01

    Reversal of diabetic nephropathy (DN) has been achieved in humans and mice, but only rarely and under special circumstances. Since progression of DN is related to podocyte loss, reversal of DN requires restoration of podocytes. Here we identified and quantified potential glomerular progenitor cells that could be a source for restored podocytes. DN was identified in 31 human renal biopsy cases and separated into morphologically early or advanced lesions. Markers of podocytes (WT-1, p57), parietal epithelial cells (claudin-1) and cell proliferation (Ki-67) were identified by immunohistochemistry. Podocyte density was progressively reduced with DN. Cells marking as podocytes (p57) were present infrequently on Bowman's capsule in controls, but significantly increased in histologically early DN. Ki-67 expressing cells were identified on the glomerular tuft and Bowman's capsule in DN, but rarely in controls. Cells marking as PECs were present on the glomerular tuft, particularly in morphologically advanced DN. These findings show evidence of phenotypic plasticity in podocyte and PEC populations and are consistent with studies in the BTBR ob/ob murine model in which reversibility of DN occurs with podocytes potentially regenerating from PEC precursors. Thus, our findings support, but do not prove, that podocytes may regenerate from PEC progenitors in human DN. If so, progression of DN may represent a modifiable net balance between podocyte loss and regeneration. PMID:26376129

  13. Ag nanoclusters could efficiently quench the photoresponse of CdS quantum dots for novel energy transfer-based photoelectrochemical bioanalysis.

    PubMed

    Zhang, Ling; Sun, Yue; Liang, Yan-Yu; He, Jian-Ping; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode, and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface, and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0pM to 10nM and the detection limit was experimentally found to be of 0.3pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development. PMID:27315518

  14. Effects of electromagnetic fields (EMF) on the chemiluminescence (CL) of murine peritoneal exudate cells

    SciTech Connect

    Caren, L.D. )

    1992-02-26

    Stimulated PEC generate microbicidal free oxygen radicals which are potentially mutagenic and possibly carcinogenic. The effects of combined alternating electric and magnetic fields on oxygen radical production were measured in this study. A Helmholtz coil and parallel plate electrodes were utilized to provide uniform field characteristics. Effects were studied at combined field frequencies of 60, 600, and 6,000 Hz. Thioglycollate-elicited PEC were exposed to EMF or placed in a far corner of the lab (controls). Following the addition of zymosan, luminol-enhanced CL was measured. No differences in CL were found for exposures to 60 Hz for 18 hr; 600 Hz for 10 hr; or 6,000 Hz for 0.75 hr. PEC exposed to 6,000 Hz for 11 hr showed a 25% increase in CL over control PEC. At 600 and 6,000 Hz, the temperature of the air and a dish of saline in the EMF apparatus was 26C, vs. 25C where the controls were kept. At 60 Hz, there was no temperature difference. These preliminary experiments indicate that under these conditions, EMF fields do not have a significant effect on this immune function.

  15. Polyethylene Films Containing Silver Nanoparticles for Applications in Food Packaging: Characterization of Physico-Chemical and Anti-Microbial Properties.

    PubMed

    Becaro, Aline A; Puti, Fernanda C; Correa, Daniel S; Paris, Elaine C; Marconcini, José M; Ferreira, Marcos D

    2015-03-01

    This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food. PMID:26413633

  16. Ferroelectric Polarization-Enhanced Photoelectrochemical Water Splitting in TiO2-BaTiO3 Core-Shell Nanowire Photoanodes.

    PubMed

    Yang, Weiguang; Yu, Yanhao; Starr, Matthew B; Yin, Xin; Li, Zhaodong; Kvit, Alexander; Wang, Shifa; Zhao, Ping; Wang, Xudong

    2015-11-11

    The performances of heterojunction-based electronic devices are extremely sensitive to the interfacial electronic band structure. Here we report a largely enhanced performance of photoelectrochemical (PEC) photoanodes by ferroelectric polarization-endowed band engineering on the basis of TiO2/BaTiO3 core/shell nanowires (NWs). Through a one-step hydrothermal process, a uniform, epitaxial, and spontaneously poled barium titanate (BTO) layer was created on single crystalline TiO2 NWs. Compared to pristine TiO2 NWs, the 5 nm BTO-coated TiO2 NWs achieved 67% photocurrent density enhancement. By numerically calculating the potential distribution across the TiO2/BTO/electrolyte heterojunction and systematically investigating the light absorption, charge injection and separation properties of TiO2 and TiO2/BTO NWs, the PEC performance gain was proved to be a result of the increased charge separation efficiency induced by the ferroelectric polarization of the BTO shell. The ferroelectric polarization could be switched by external electric field poling and yielded PEC performance gain or loss based on the direction of the polarization. This study evidence that the piezotronic effect (ferroelectric or piezoelectric potential-induced band structure engineering) holds great promises in improving the performance of PEC photoelectrodes in addition to chemistry and structure optimization.

  17. Photocatalytic and photoelectrochemical performance of Ta3N5 microcolumn films fabricated using facile reactive sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Der-Hwa; Chang, Kao-Shuo

    2016-08-01

    This paper presents the photocatalytic and photoelectrochemical (PEC) properties of Ta3N5 microcolumn films. The highlights include (1) overcoming the fundamental barrier of standard reactive sputtering for fabricating microcolumns; (2) preventing unnecessary complexity from complicating facile sputtering; (3) an alternative but effective approach for fabricating Ta3N5 without using caustic NH3 gases; (4) investigating morphology tuning for favorable photocatalysis and PEC reactions; and (5) elucidating the relationships of the structures, morphologies, and properties of Ta3N5 microcolumns. High-resolution transmission electron microscopy and selective-area electron diffraction verified the polycrystallinity of Ta3N5 microcolumns, of which the elemental compositions and stoichiometry were measured using electron-probe energy dispersive spectroscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The corresponding band gap was determined to be approximately 2.1 eV. The sample exhibited a superior photodegradation capability; the photodegradation rate constant k was determined to be approximately 1.4 times higher than that of P25 under UV irradiation. A photocatalytic and PEC cycling test indicated the photodegradation reusability and photostability of the Ta3N5 microcolumns. The incident photon-to-current efficiency performance reached 6%, suggesting that these microcolumns hold potential for application in PEC devices.

  18. Murine Model of Chemotherapy-Induced Extraintestinal Pathogenic Escherichia coli Translocation

    PubMed Central

    Green, Sabrina I.; Ajami, Nadim J.; Ma, Li; Poole, Nina M.; Price, Roger E.; Petrosino, Joseph F.

    2015-01-01

    Escherichia coli is a major cause of life-threatening infections in patients with neutropenia, particularly those receiving chemotherapy for the treatment of cancer. In most cases, these infections originate from opportunistic strains living within the patient's gastrointestinal tract which then translocate to major organ systems. There are no animal models that faithfully recapitulate these infections, and, as such, the host or bacterial factors that govern this process remain unidentified. We present here a novel model of chemotherapy-induced bacterial translocation of E. coli. Oral gavage of BALB/c mice with a clinical isolate of extraintestinal pathogenic E. coli (ExPEC) leads to stable and long-term colonization of the murine intestine. Following the induction of neutropenia with the chemotherapeutic drug cyclophosphamide, ExPEC translocates from the intestine to the lungs, liver, spleen, and kidneys with concomitant morbidity in infected animals. Translocation can also occur in mice bearing mammary tumors, even in the absence of chemotherapy. Translocation of ExPEC is also associated with an increase of the diversity of bacterial DNA detected in the blood. This is the first report of a chemotherapy-based animal model of ExPEC translocation in cancerous mice, a system that can be readily used to identify important virulence factors for this process. PMID:26034214

  19. Semiconducting materials for photoelectrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Sivula, Kevin; van de Krol, Roel

    2016-02-01

    To achieve a sustainable society with an energy mix primarily based on solar energy, we need methods of storing energy from sunlight as chemical fuels. Photoelectrochemical (PEC) devices offer the promise of solar fuel production through artificial photosynthesis. Although the idea of a carbon-neutral energy economy powered by such ‘artificial leaves’ is intriguing, viable PEC energy conversion on a global scale requires the development of devices that are highly efficient, stable and simple in design. In this Review, recently developed semiconductor materials for the direct conversion of light into fuels are scrutinized with respect to their atomic constitution, electronic structure and potential for practical performance as photoelectrodes in PEC cells. The processes of light absorption, charge separation and transport, and suitable energetics for energy conversion in PEC devices are emphasized. Both the advantageous and unfavourable aspects of multinary oxides, oxynitrides, chalcogenides, classic semiconductors and carbon-based semiconductors are critically considered on the basis of their experimentally demonstrated performance and predicted properties.

  20. The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis

    SciTech Connect

    Yan, Danhua; Tao, Jing; Kisslinger, Kim; Cen, Jiajie; Wu, Qiyuan; Orlov, Alexander; Liu, Mingzhao

    2015-10-13

    In this study, we develop a novel technique for preparing high quality Ti-doped hematite thin films for photoelectrochemical (PEC) water splitting, through sputtering deposition of metallic iron films from an iron target embedded with titanium (dopants) pellets, followed by a thermal oxidation step that turns the metal films into doped hematite. It is found that the hematite domain size can be tuned from ~10 nm to over 100 nm by adjusting the sputtering atmosphere from more oxidative to mostly inert. The better crystallinity at a larger domain size ensures excellent PEC water splitting performance, leading to record high photocurrent from pure planar hematite thin films on FTO substrates. Titanium doping further enhances the PEC performance of hematite photoanodes. The photocurrent is improved by 50%, with a titanium dopant concentration as low as 0.5 atom%. It is also found that the role of the titanium dopant in improving the PEC performance is not apparently related to the films’ electrical conductivity which had been widely believed, but is more likely due to the passivation of surface defects by the titanium dopants.

  1. The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis

    DOE PAGESBeta

    Yan, Danhua; Tao, Jing; Kisslinger, Kim; Cen, Jiajie; Wu, Qiyuan; Orlov, Alexander; Liu, Mingzhao

    2015-10-13

    In this study, we develop a novel technique for preparing high quality Ti-doped hematite thin films for photoelectrochemical (PEC) water splitting, through sputtering deposition of metallic iron films from an iron target embedded with titanium (dopants) pellets, followed by a thermal oxidation step that turns the metal films into doped hematite. It is found that the hematite domain size can be tuned from ~10 nm to over 100 nm by adjusting the sputtering atmosphere from more oxidative to mostly inert. The better crystallinity at a larger domain size ensures excellent PEC water splitting performance, leading to record high photocurrent frommore » pure planar hematite thin films on FTO substrates. Titanium doping further enhances the PEC performance of hematite photoanodes. The photocurrent is improved by 50%, with a titanium dopant concentration as low as 0.5 atom%. It is also found that the role of the titanium dopant in improving the PEC performance is not apparently related to the films’ electrical conductivity which had been widely believed, but is more likely due to the passivation of surface defects by the titanium dopants.« less

  2. Guiding Documents for Environmental Education Centres: An Analysis in the Spanish Context

    ERIC Educational Resources Information Center

    Medir, Rosa Maria; Heras, Raquel; Geli, Anna Maria

    2014-01-01

    Guiding documents under the "PEC" acronym are commonly used in environmental education centres (EECs) in Spain. They are written documents that are seen as necessary tools to safeguard quality. In this study, we analyse the guiding documents of twenty-three EECs in the province of Girona (Catalonia, Spain) in order to understand their…

  3. The Effects of Behavioral Skills Training on Implementation of the Picture Exchange Communication System

    ERIC Educational Resources Information Center

    Rosales, Rocio; Stone, Karen; Rehfeldt, Ruth Anne

    2009-01-01

    The effectiveness of a behavioral skills training (BST) package to teach the implementation of the first three phases of the picture exchange communication system (PECS) was evaluated with 3 adults who had no history teaching any functional communication system. A multiple baseline design across participants was used to evaluate the effectiveness…

  4. The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes.

    PubMed

    Zhang, Yanpu; Yildirim, Erol; Antila, Hanne S; Valenzuela, Luis D; Sammalkorpi, Maria; Lutkenhaus, Jodie L

    2015-10-01

    Polyelectrolyte complexes (PECs) form by mixing polycation and polyanion solutions together, and have been explored for a variety of applications. One challenge for PEC processing and application is that under certain conditions the as-formed PECs aggregate and precipitate out of suspension over the course of minutes to days. This aggregation is governed by several factors such as electrostatic repulsion, van der Waals attractions, and hydrophobic interactions. In this work, we explore the boundary between colloidally stable and unstable complexes as it is influenced by polycation/polyanion mixing ratio and ionic strength. The polymers examined are poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate) (PSS). Physical properties such as turbidity, hydrodynamic size, and zeta potential are investigated upon complex formation. We also perform detailed molecular dynamics simulations to examine the structure and effective charge distribution of the PECs at varying mixing ratios and salt concentrations to support the experimental findings. The results suggest that the colloidally stable/unstable boundary possibly marks the screening effects from added salt, resulting in weakly charged complexes that aggregate. At higher salt concentrations, the complexes initially form and then gradually dissolve into solution.

  5. Osteoinductive activity of insulin-functionalized cell culture surfaces obtained using diazonium chemistry

    NASA Astrophysics Data System (ADS)

    Mikulska, Anna; Filipowska, Joanna; Osyczka, Anna; Nowakowska, Maria; Szczubiałka, Krzysztof

    2014-12-01

    Polymeric surfaces suitable for cell culture (DR/Pec) were constructed from diazoresin (DR) and pectin (Pec) in a form of ultrathin films using the layer-by-layer (LbL) technique. The surfaces were functionalized with insulin using diazonium chemistry. Such functionalized surfaces were used to culture human mesenchymal stem cells (hMSCs) to assess their suitability for bone tissue engineering and regeneration. The activity of insulin immobilized on the surfaces (DR/Pec/Ins) was compared to that of insulin dissolved in the culture medium. Human MSC grown on insulin-immobilized DR/Pec surfaces displayed increased proliferation and higher osteogenic activity. The latter was determined by means of alkaline phosphatase (ALP) activity, which increases at early stages of osteoblasts differentiation. Insulin dissolved in the culture medium did not stimulate cell proliferation and its osteogenic activity was significantly lower. Addition of recombinant human bone morphogenetic protein 2 (rhBMP-2) to the culture medium further increased ALP activity in hMSCs indicating additive osteogenic action of immobilized insulin and rhBMP-2

  6. Education for Peace: A Conference Report from Kyoto. Peace Education Reports No. 6.

    ERIC Educational Resources Information Center

    Bjerstedt, Ake, Ed.

    Conference sessions of the Peace Education Commission (PEC), a transnational network of people interested in peace education and research related to peace education, are reported in this document. Following an introductory overview of the conference as a whole, the report is divided into four parts. The first part contains three area studies; that…

  7. Exposure simulation for pharmaceuticals in European surface waters with GREAT-ER.

    PubMed

    Schowanek, Diederik; Webb, Simon

    2002-05-10

    The Geo-referenced Regional Exposure Assessment Tool for European Rivers (GREAT-ER) model was developed as an aquatic chemical exposure prediction tool for use within environmental risk assessment (ERA) schemes and river basin management. The GREAT-ER software calculates the distribution of predicted environmental concentrations (PECs) of consumer chemicals in surface waters, for individual river stretches, as well as representative average PECs for entire catchments. The system uses an ARC/INFO-ArcView (ESRI) based Geographical Information System (GIS) for data storage and visualization, combined with simple mathematical models for prediction of chemical fate. Use of GREAT-ER 1.03 to derive PECs is illustrated for Ethinyl Oestradiol, Paracetamol, Aspirin, Dextropropoxyphene, Clofibrate and Oxytetracycline in three river basins, i.e. Aire (UK), Lambro (Italy) and Rur (Germany). In contrast with household consumer chemicals the transformation of pharmaceuticals in the human body needs to be incorporated in the emission estimation. The "PECinitial" of these pharmaceuticals in surface waters ranges from >1 microg/l (Oxytetracycline and Paracetamol) down to <1 ng/l (Ethinyl Oestradiol). Risk characterization employing PECs or measured environmental concentrations (MECs) and predicted-no-effect-concentrations (PNECs) from available ecotoxicity data is also reported. PMID:11988357

  8. Comparative study of photocatalytic and photoelectrocatalytic properties of alachlor using different morphology TiO2/Ti photoelectrodes.

    PubMed

    Xin, Yanjun; Liu, Huiling; Han, Lei; Zhou, Yabin

    2011-09-15

    Wormhole-shaped TiO(2)/Ti (WT) and nanotube-shaped TiO(2)/Ti (TNT) photoelectrodes were prepared by anodic oxidation method. The morphology and structure were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that both crystal types of WT and TNT photoelectrodes were composed of anatase and rutile TiO(2) phases; however TNT photoelectrodes had highly ordered nanostructure. The photoelectrochemical (PECH) and photoelectrocatalytic (PEC) properties of WT and TNT photoelectrodes were investigated by photocurrent transient, open-circuit potential and degradation rate of alachlor under the artificial solar light illumination. All results showed that TNT photoelectrodes prepared in NaF-Na(2)SO(4) solution have more excellent photoelectron properties than WT photoelectrodes prepared in H(2)SO(4) solution. The photocatalytic (PC) and PEC experiments of alachlor showed that PC and PEC activities of TNT photoelectrodes were superior to WT photoelectrodes. At applied bias potentials the degradation rate of alachlor at TNT photoelectrodes increased significantly to 94.5%. The higher PC and PEC performance of TNT photoelectrodes were ascribed to the long-range ordered structure and short-orientation diffusion distance of photogenerated carries.

  9. A label-free photoelectrochemical aptasensor based on nitrogen-doped graphene quantum dots for chloramphenicol determination.

    PubMed

    Liu, Yong; Yan, Kai; Okoth, Otieno Kevin; Zhang, Jingdong

    2015-12-15

    A photoelectrochemical (PEC) sensing platform for chloramphenicol (CAP) detection was constructed using nitrogen-doped graphene quantum dots (N-GQDs) as transducer species and label-free aptamer as biological recognition element. N-GQDs, synthesized via a facile one-step hydrothermal method, were explored to achieve highly efficient photon-to-electricity conversion under visible light irradiation. The obtained N-GQDs were characterized by transmission electron microscopy (TEM), which displayed a narrow size distribution with a mean diameter of 2.14 nm. The X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopic (FT-IR) analysis confirmed that nitrogen was successfully doped in GQDs. The UV-visible absorption spectra indicated that nitrogen doping obviously enhanced the absorption of GQDs in visible light region. As a result, the PEC activity of GQDs was promoted by nitrogen doping. Additionally, the π-conjugated structure of N-GQDs provided an excellent platform for aptamer immobilization via π-π stacking interaction. Such an aptamer/N-GQDs based sensor showed a linear PEC response to CAP concentration in the range of 10-250 nM with a detection limit (3 S/N) of 3.1 nM. The developed PEC aptasensor exhibited high sensitivity and selectivity, good reproducibility and high stability. PMID:26264269

  10. Thermal-Responsive Behavior of a Cell Compatible Chitosan/Pectin Hydrogel.

    PubMed

    Birch, Nathan P; Barney, Lauren E; Pandres, Elena; Peyton, Shelly R; Schiffman, Jessica D

    2015-06-01

    Biopolymer hydrogels are important materials for wound healing and cell culture applications. While current synthetic polymer hydrogels have excellent biocompatibility and are nontoxic, they typically function as a passive matrix that does not supply any additional bioactivity. Chitosan (CS) and pectin (Pec) are natural polymers with active properties that are desirable for wound healing. Unfortunately, the synthesis of CS/Pec materials have previously been limited by harsh acidic synthesis conditions, which further restricted their use in biomedical applications. In this study, a zero-acid hydrogel has been synthesized from a mixture of chitosan and pectin at biologically compatible conditions. For the first time, we demonstrated that salt could be used to suppress long-range electrostatic interactions to generate a thermoreversible biopolymer hydrogel that has temperature-sensitive gelation. Both the hydrogel and the solution phases are highly elastic, with a power law index of close to -1. When dried hydrogels were placed into phosphate buffered saline solution, they rapidly rehydrated and swelled to incorporate 2.7× their weight. As a proof of concept, we removed the salt from our CS/Pec hydrogels, thus, creating thick and easy to cast polyelectrolyte complex hydrogels, which proved to be compatible with human marrow-derived stem cells. We suggest that our development of an acid-free CS/Pec hydrogel system that has excellent exudate uptake, holds potential for wound healing bandages.

  11. Synthesis and water absorption transport mechanism of a pH-sensitive polymer network structured on vinyl-functionalized pectin.

    PubMed

    Guilherme, Marcos R; Moia, Thais A; Reis, Adriano V; Paulino, Alexandre T; Rubira, Adley F; Mattoso, Luiz H C; Muniz, Edvani C; Tambourgi, Elias B

    2009-01-12

    Polysaccharide-structured copolymer hydrogel having excellent pH-sensitivity was developed from N,N-dimethylacrylamide (DMAc) and vinyl-functionalized Pectin (Pec). The Pec was vinyl-functionalized by way of chemical reaction with glycidyl metacrylate (GMA) in water under acidic and thermal stimuli. 13C NMR, 1H NMR, and FT-IR spectra revealed that the vinyl groups coming from the GMA were attached onto backbone of the polysaccharide. The hydrogels were obtained by polymerization of the Pec-vinyl with the DMAc. 13C-CP/MAS NMR and FTIR spectra confirmed that the gelling process occurred by way of the vinyl groups attached on Pec-vinyl backbone. The values of apparent swelling rate constant (k) decreased appreciably for pH greater than 6, demonstrating the swelling process of the hydrogel becomes slower at more alkaline conditions. There was an increase of diffusional exponent (n) with increasing pH of the surrounding liquid. This means the water absorption profile becomes more dependent on the polymer relaxation in basified swelling media. In this condition, a longer water absorption half-time (t1/2) was verified, suggesting the polymer relaxation mechanism of the hydrogel would have a considerable effect on the t1/2.

  12. Model to Test Electric Field Comparisons in a Composite Fairing Cavity

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Burford, Janessa

    2013-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This study shows cumulative distribution function (CDF) comparisons of composite a fairing electromagnetic field data obtained by computational electromagnetic 3D full wave modeling and laboratory testing. This work is an extension of the bare aluminum fairing perfect electric conductor (PEC) model. Test and model data correlation is shown.

  13. Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide Nanowire Arrays.

    PubMed

    Kornienko, Nikolay; Gibson, Natalie A; Zhang, Hao; Eaton, Samuel W; Yu, Yi; Aloni, Shaul; Leone, Stephen R; Yang, Peidong

    2016-05-24

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising strategy to absorb solar energy and directly convert it into a dense storage medium in the form of chemical bonds. The continual development and improvement of individual components of PEC systems is critical toward increasing the solar to fuel efficiency of prototype devices. Within this context, we describe a study on the growth of wurtzite indium phosphide (InP) nanowire (NW) arrays on silicon substrates and their subsequent implementation as light-absorbing photocathodes in PEC cells. The high onset potential (0.6 V vs the reversible hydrogen electrode) and photocurrent (18 mA/cm(2)) of the InP photocathodes render them as promising building blocks for high performance PEC cells. As a proof of concept for overall system integration, InP photocathodes were combined with a nanoporous bismuth vanadate (BiVO4) photoanode to generate an unassisted solar water splitting efficiency of 0.5%. PMID:27124203

  14. Energetics at the Surface of Photoelectrodes and Its Influence on the Photoelectrochemical Properties.

    PubMed

    Thorne, James E; Li, Song; Du, Chun; Qin, Gaowu; Wang, Dunwei

    2015-10-15

    Photoelectrochemistry (PEC) holds potential as a direct route for solar energy storage. Its performance is governed by how efficiently photoexcited charges are separated and how fast the charges are transferred to the solution, both of which are highly sensitive to the photoelectrode surfaces near the electrolyte. While other aspects of a PEC system, such as the light-absorbing materials and the catalysts that facilitate charge transfer, have been extensively examined in the past, an underwhelming amount of attention has been paid to the energetics at the photoelectrode/electrolyte interface. The lack of understanding of this interface is an important reason why many photoelectrode materials fail to deliver the expected performance in harvesting solar energy in a PEC system. Using hematite (α-Fe2O3) as a material platform, we present in this Perspective how surface modifications can alter the energetics and the resulting consequences on the overall PEC performance. It has been shown that a detailed understanding of the photoelectrode/eletrolyte interfaces can contribute significantly to improving the performance of hematite, which enabled unassisted solar water splitting when combined with an amorphous Si photocathode. PMID:26722780

  15. Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems

    USGS Publications Warehouse

    MacDonald, D.D.; Ingersoll, C.G.; Berger, T.A.

    2000-01-01

    Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R2 = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems.

  16. Ferroelectric Polarization-Enhanced Photoelectrochemical Water Splitting in TiO2-BaTiO3 Core-Shell Nanowire Photoanodes.

    PubMed

    Yang, Weiguang; Yu, Yanhao; Starr, Matthew B; Yin, Xin; Li, Zhaodong; Kvit, Alexander; Wang, Shifa; Zhao, Ping; Wang, Xudong

    2015-11-11

    The performances of heterojunction-based electronic devices are extremely sensitive to the interfacial electronic band structure. Here we report a largely enhanced performance of photoelectrochemical (PEC) photoanodes by ferroelectric polarization-endowed band engineering on the basis of TiO2/BaTiO3 core/shell nanowires (NWs). Through a one-step hydrothermal process, a uniform, epitaxial, and spontaneously poled barium titanate (BTO) layer was created on single crystalline TiO2 NWs. Compared to pristine TiO2 NWs, the 5 nm BTO-coated TiO2 NWs achieved 67% photocurrent density enhancement. By numerically calculating the potential distribution across the TiO2/BTO/electrolyte heterojunction and systematically investigating the light absorption, charge injection and separation properties of TiO2 and TiO2/BTO NWs, the PEC performance gain was proved to be a result of the increased charge separation efficiency induced by the ferroelectric polarization of the BTO shell. The ferroelectric polarization could be switched by external electric field poling and yielded PEC performance gain or loss based on the direction of the polarization. This study evidence that the piezotronic effect (ferroelectric or piezoelectric potential-induced band structure engineering) holds great promises in improving the performance of PEC photoelectrodes in addition to chemistry and structure optimization. PMID:26492362

  17. A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles.

    PubMed

    Li, Hongbo; Qiao, Yunfei; Li, Jing; Fang, Hailin; Fan, Dahe; Wang, Wei

    2016-03-15

    Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor.

  18. Biofuel from biomass via photo-electrochemical reactions: An overview

    NASA Astrophysics Data System (ADS)

    Ibrahim, N.; Kamarudin, S. K.; Minggu, L. J.

    2014-08-01

    Biomass is attracting a great deal of attention as a renewable energy resource to reduce carbon dioxide (CO2) emissions. Converting biomass from municipal, agricultural and livestock into biofuel and electrical power has significant environmental and economic advantages. The conversion of biomass into practical energy requires elegant designs and further investigation. Thus, biomass is a promising renewable energy source due to its low production cost and simple manufacturing processes. Biofuel (hydrogen and methanol) from biomass will be possible to be used for transportation with near-zero air pollution, involves efficient uses of land and major contribution to reduce dependence on insecure source of petroleum. Photoelectrochemical (PEC) reactions study has potential pathway for producing fuel from biomass and bio-related compound in the near future. This review highlights recent work related to the PEC conversion of biomass and bio-related compounds into useful biofuels and electricity. This review covers different types of photochemical reaction cells utilizing various types of organic and inorganic waste. It also presents recent developments in photoelectrodes, photocatalysts and electrolytes as well as the production of different types of fuel from PEC cells and highlights current developments and problems in PEC reactions.

  19. The Picture Exchange Communication System: Digital Photographs versus Picture Symbols

    ERIC Educational Resources Information Center

    Jonaitis, Carmen

    2011-01-01

    The Picture Exchange Communication System (PECS) is an augmentative and alternative system (AAC) used to improve and increase communication for children with Autism Spectrum Disorder (ASD) and other developmental disorders. Research addressing the efficacy of this system is increasing; however, there is limited information published that evaluates…

  20. Brief Report: Randomized Test of the Efficacy of Picture Exchange Communication System on Highly Generalized Picture Exchanges in Children with ASD

    ERIC Educational Resources Information Center

    Yoder, Paul J.; Lieberman, Rebecca G.

    2010-01-01

    A randomized control trial comparing two social-communication interventions in young children with autism examined far-transfer of the use of picture exchange to communicate. Thirty-six children were randomly assigned to one of two treatment conditions, one of which was the Picture Exchange Communication System (PECS). All children had access to…

  1. A Further Evaluation of Behavioral Skills Training for Implementation of the Picture Exchange Communication System

    ERIC Educational Resources Information Center

    Homlitas, Christa; Rosales, Rocío; Candel, Lindsay

    2014-01-01

    We evaluated the effectiveness of a behavioral skills training package to teach implementation of Phases 1, 2, and 3A of the picture exchange communication system (PECS) to teachers employed at a therapeutic center for children with autism. Probes in the natural environment and follow-up were conducted with children who were assigned to work with…

  2. Interaction of Participant Characteristics and Type of AAC with Individuals with ASD: A Meta-Analysis

    ERIC Educational Resources Information Center

    Ganz, Jennifer B.; Mason, Rose A.; Goodwyn, Fara D.; Boles, Margot B.; Heath, Amy K.; Davis, John L.

    2014-01-01

    Individuals with autism spectrum disorders (ASD) and complex communication needs often rely on augmentative and alternative communication (AAC) as a means of functional communication. This meta-analysis investigated how individual characteristics moderate effectiveness of three types of aided AAC: the Picture Exchange Communication System (PECS),…

  3. The Impact of the Picture Exchange Communication System on Requesting and Speech Development in Preschoolers with Autism Spectrum Disorders and Similar Characteristics

    ERIC Educational Resources Information Center

    Ganz, Jennifer B.; Simpson, Richard L.; Corbin-Newsome, Jawanda

    2008-01-01

    By definition children with autism spectrum disorders (ASD) experience difficulty understanding and using language. Accordingly, visual and picture-based strategies such as the Picture Exchange Communication System (PECS) show promise in ameliorating speech and language deficits. This study reports the results of a multiple baseline across…

  4. Video Feedforward for Rapid Learning of a Picture-Based Communication System

    ERIC Educational Resources Information Center

    Smith, Jemma; Hand, Linda; Dowrick, Peter W.

    2014-01-01

    This study examined the efficacy of video self modeling (VSM) using feedforward, to teach various goals of a picture exchange communication system (PECS). The participants were two boys with autism and one man with Down syndrome. All three participants were non-verbal with no current functional system of communication; the two children had long…

  5. Teaching Children with Autism to Engage in Peer-Directed Mands Using a Picture Exchange Communication System

    ERIC Educational Resources Information Center

    Paden, Amber R.; Kodak, Tiffany; Fisher, Wayne W.; Gawley-Bullington, Elizabeth M.; Bouxsein, Kelly J.

    2012-01-01

    We evaluated differential reinforcement of alternative behavior (DRA) plus prompting to increase peer-directed mands for preferred items using a picture exchange communication system (PECS). Two nonvocal individuals with autism participated. Independent mands with a peer increased with the implementation of DRA plus prompting for both…

  6. Thin-film photovoltaic cells: long-term metal(loid) leaching at their end-of-life.

    PubMed

    Zimmermann, Yannick-Serge; Schäffer, Andreas; Corvini, Philippe F-X; Lenz, Markus

    2013-11-19

    The photovoltaic effect of thin-film copper indium gallium selenide cells (CIGS) is conferred by the latter elements. Organic photovoltaic cells (OPV), relying on organic light-absorbing molecules, also contain a variety of metals (e.g., Zn, Al, In, Sn, Ag). The environmental impact of such technologies is largely unknown, in particular when the physical integrity deteriorates upon end-of-life, possibly facilitating cell constituent leaching. This study analyzed long-term inorganic leaching from damaged OPV and CIGS into different model waters. Leachate concentrations were put into perspective by calculating the predicted environmental concentrations (PEC) for several scenarios. Roof-top acidic rain runoff from CIGS was found to be the predominant emission source for metals and metalloids, with Cd released to such extents that PEC (173.4 μg Cd L(-1)) would considerably exceed acute toxicity concentrations for Daphnia magna . Other PEC for CIGS (9.9 mg Mo L(-1) and 9.4 μg Se L(-1)) were in the range of teratogenic effects. In contrast, OPV released little metals with calculated PEC being below even conservative drinking water guidelines. Time-resolved single-particle ICP-MS indicated that some metals (Zn, Mo, Ag) were in nanoparticulate form, raising nanotoxicity concerns. Leaching kinetics called for revision of existing standardized (accelerated) leaching protocols because long-term release was most relevant.

  7. Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide Nanowire Arrays.

    PubMed

    Kornienko, Nikolay; Gibson, Natalie A; Zhang, Hao; Eaton, Samuel W; Yu, Yi; Aloni, Shaul; Leone, Stephen R; Yang, Peidong

    2016-05-24

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising strategy to absorb solar energy and directly convert it into a dense storage medium in the form of chemical bonds. The continual development and improvement of individual components of PEC systems is critical toward increasing the solar to fuel efficiency of prototype devices. Within this context, we describe a study on the growth of wurtzite indium phosphide (InP) nanowire (NW) arrays on silicon substrates and their subsequent implementation as light-absorbing photocathodes in PEC cells. The high onset potential (0.6 V vs the reversible hydrogen electrode) and photocurrent (18 mA/cm(2)) of the InP photocathodes render them as promising building blocks for high performance PEC cells. As a proof of concept for overall system integration, InP photocathodes were combined with a nanoporous bismuth vanadate (BiVO4) photoanode to generate an unassisted solar water splitting efficiency of 0.5%.

  8. Environmental Risk Assessment (ERA) of diclofenac and ibuprofen: a public health perspective.

    PubMed

    Gamarra, Javier Salvador; Godoi, Ana Flávia Locateli; de Vasconcelos, Eliane Carvalho; de Souza, Kennedy Medeiros Tavares; de Oliveira, Cintia Mara Ribas

    2015-02-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) have been widely used in human and veterinary medicine, representing potential aquatic environmental contamination. This study aimed to perform an Environmental Risk Assessment (ERA) of NSAIDs diclofenac (Dic) and ibuprofen (Ibu) in cities of the state of Paraná, Brazil, over the course of three years, by using available data from the Brazilian Public Health System. The environmental risk (ER) was assessed by employing the European Medicines Agency (EMeA) approach, and predicted environmental concentrations (PECs) were calculated. The refined PECs considered the drug metabolism and the excretion data, and also the sewage treatment plant removal rates of biological filters and activated sludge processes to define environmental scenarios. References to the predicted no effect concentration (PNEC) for these pharmaceuticals were considered, and the PEC/PNEC ratio was calculated; ratio values ⩾ 1 suggested an ER. Environmental risk was conducted on several cities, and the lack of an adequate sanitation system in the majority of Paraná cities forecasts a significant concern with the exposure to possible environmental damages in those cities. The high PEC/PNEC ratios in several cities showed that current usage patterns of these drugs constitute an environmental issue in need of resolution by health and environmental authorities.

  9. A label-free photoelectrochemical aptasensor based on nitrogen-doped graphene quantum dots for chloramphenicol determination.

    PubMed

    Liu, Yong; Yan, Kai; Okoth, Otieno Kevin; Zhang, Jingdong

    2015-12-15

    A photoelectrochemical (PEC) sensing platform for chloramphenicol (CAP) detection was constructed using nitrogen-doped graphene quantum dots (N-GQDs) as transducer species and label-free aptamer as biological recognition element. N-GQDs, synthesized via a facile one-step hydrothermal method, were explored to achieve highly efficient photon-to-electricity conversion under visible light irradiation. The obtained N-GQDs were characterized by transmission electron microscopy (TEM), which displayed a narrow size distribution with a mean diameter of 2.14 nm. The X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopic (FT-IR) analysis confirmed that nitrogen was successfully doped in GQDs. The UV-visible absorption spectra indicated that nitrogen doping obviously enhanced the absorption of GQDs in visible light region. As a result, the PEC activity of GQDs was promoted by nitrogen doping. Additionally, the π-conjugated structure of N-GQDs provided an excellent platform for aptamer immobilization via π-π stacking interaction. Such an aptamer/N-GQDs based sensor showed a linear PEC response to CAP concentration in the range of 10-250 nM with a detection limit (3 S/N) of 3.1 nM. The developed PEC aptasensor exhibited high sensitivity and selectivity, good reproducibility and high stability.

  10. CdSxSe1-x nanowhiskers sensitized Nitrogen-doped TiO2: 3D-branched photoelectrode and its photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Lang, Jihui; Su, Jun; Li, Xiuyan; Zhai, Hongju; Wang, Jingshu; Yang, Jinghai

    2016-05-01

    Light absorption, appropriate interfacial redox reaction, and photogenerated charge carriers separation are the three-key-aspect of efficient photoelectrochemical (PEC) devices. 3D-branched nanostructure photoelectrode was prepared by growing CdSxSe1-x nanowhiskers around the head of Nitrogen-doped TiO2 nanorods (NRs). PEC cells were assembled according to the aforesaid three-key-aspect. Synergistic effect of CdSxSe1-x sensitization and substituted N dopants was confirmed on the improved photocurrent properties of CdSxSe1-x/N-TiO2 photoelectrode. Meanwhile, the inferred type II band edge alignment in it facilitated the separation of photogenerated charge carriers. Moreover, 3D hierarchical nanostructure of CdSxSe1-x/N-TiO2 provided higher specific surface area and the result of more active sites for PEC reaction. Our work would be of some benefits to design and manufacture high performance photoelectrodes and assemble efficient PEC cells for solar energy conversion.

  11. Polyethylene Films Containing Silver Nanoparticles for Applications in Food Packaging: Characterization of Physico-Chemical and Anti-Microbial Properties.

    PubMed

    Becaro, Aline A; Puti, Fernanda C; Correa, Daniel S; Paris, Elaine C; Marconcini, José M; Ferreira, Marcos D

    2015-03-01

    This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food.

  12. Photoelectrochemical etching of epitaxial InGaN thin films: Self-limited kinetics and nanostructuring

    DOE PAGESBeta

    Xiao, Xiaoyin; Fischer, Arthur J.; Coltrin, Michael E.; Lu, Ping; Koleske, Daniel D.; Wang, George T.; Polsky, Ronen; Tsao, Jeffrey Y.

    2014-10-22

    We report here the characteristics of photoelectrochemical (PEC) etching of epitaxial InGaN semiconductor thin films using narrowband lasers with linewidth less than ~1 nm. In the initial stages of PEC etching, when the thin film is flat, characteristic voltammogram shapes are observed. At low photo-excitation rates, voltammograms are S-shaped, indicating the onset of a voltage-independent rate-limiting process associated with electron-hole-pair creation and/or annihilation. At high photo-excitation rates, voltammograms are superlinear in shape, indicating, for the voltage ranges studied here, a voltage-dependent rate-limiting process associated with surface electrochemical oxidation. As PEC etching proceeds, the thin film becomes rough at the nanoscale,more » and ultimately evolves into an ensemble of nanoparticles. As a result, this change in InGaN film volume and morphology leads to a characteristic dependence of PEC etch rate on time: an incubation time, followed by a rise, then a peak, then a slow decay.« less

  13. Photoelectrochemical etching of epitaxial InGaN thin films: Self-limited kinetics and nanostructuring

    SciTech Connect

    Xiao, Xiaoyin; Fischer, Arthur J.; Coltrin, Michael E.; Lu, Ping; Koleske, Daniel D.; Wang, George T.; Polsky, Ronen; Tsao, Jeffrey Y.

    2014-10-22

    We report here the characteristics of photoelectrochemical (PEC) etching of epitaxial InGaN semiconductor thin films using narrowband lasers with linewidth less than ~1 nm. In the initial stages of PEC etching, when the thin film is flat, characteristic voltammogram shapes are observed. At low photo-excitation rates, voltammograms are S-shaped, indicating the onset of a voltage-independent rate-limiting process associated with electron-hole-pair creation and/or annihilation. At high photo-excitation rates, voltammograms are superlinear in shape, indicating, for the voltage ranges studied here, a voltage-dependent rate-limiting process associated with surface electrochemical oxidation. As PEC etching proceeds, the thin film becomes rough at the nanoscale, and ultimately evolves into an ensemble of nanoparticles. As a result, this change in InGaN film volume and morphology leads to a characteristic dependence of PEC etch rate on time: an incubation time, followed by a rise, then a peak, then a slow decay.

  14. An environmental risk assessment for oseltamivir (Tamiflu) for sewage works and surface waters under seasonal-influenza- and pandemic-use conditions.

    PubMed

    Straub, Jürg Oliver

    2009-09-01

    In the event of an influenza pandemic, anti-viral medications such as oseltamivir (Tamiflu) are expected to be used in high amounts over a duration of several weeks. Oseltamivir has been predicted to reach high concentrations in surface waters and sewage works. New oseltamivir environmental fate and toxicity studies permit an environmental risk assessment (ERA) under seasonal- and pandemic-use scenarios. The environmental fate data for sewage works (no removal), surface waters (no significant degradation), and water/sediment systems (>50% primary degradation in 100 days) were used for the derivation of new predicted environmental concentrations (PECs) for western Europe and the River Lee catchment in the UK. Existing worst-case PECs for western Europe, the River Lee catchment in the UK and the Lower Colorado basin in the USA under pandemic conditions (< or =98.1 microg/L for surface waters, < or =348 microg/L for sewage works) were also considered for the ERA. PECs were compared with predicted no-effect concentrations (PNECs) based on new chronic ecotoxicity data (no observed effect concentration for algae, daphnia, and fish > or =1 mg/L). Based on all PEC/PNEC risk ratios, no significant risk is evident to surface waters or sewage works during both regular seasonal-use and high pandemic-use of oseltamivir. PMID:19560203

  15. Model to Test Electric Field Comparisons in a Composite Fairing Cavity

    NASA Technical Reports Server (NTRS)

    Trout, Dawn; Burford, Janessa

    2012-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This study shows cumulative distribution function (CDF) comparisons of composite . a fairing electromagnetic field data obtained by computational electromagnetic 3D full wave modeling and laboratory testing. This work is an extension of the bare aluminum fairing perfect electric conductor (PEC) model. Test and model data correlation is shown.

  16. A highly selective and picomolar level photoelectrochemical sensor for PCB 101 detection in environmental water samples.

    PubMed

    Shi, Huijie; Zhao, Jinzhi; Wang, Yingling; Zhao, Guohua

    2016-07-15

    A highly selective and sensitive photoelectrochemical (PEC) sensor was fabricated for fast and convenient detection of PCB 101 in environmental water samples with a low detection limit of 1.0×10(-14)molL(-1) based on single crystalline TiO2 nanorods (NRs). By integration with molecular imprinting (MI) technique, the PEC sensor's selectivity towards PCB 101 was significantly improved, so that the interference caused by 100-fold excess of PCB 126 and PCB 77 which had similar structure with PCB 101 was below 37%, not to mention other coexisted pollutants. This high selectivity could be attributed to the high-quality expression of the molecular imprinting sites on the rigid and smooth surface of single crystalline TiO2 NRs on which PCB 101 could be selectively and preferentially adsorbed. The oriented and multiple halogen bonds formed between PCB 101 and the molecular imprinting sites played a critical role in improving the recognition ability of the PEC sensor. Meanwhile, the one dimensional nanorods structure of TiO2 was beneficial for the efficient separation of photogenerated electrons and holes, leading to enhanced photocurrent response and further improving the sensitivity of the PEC sensor. PMID:27016911

  17. Delta-short consensus repeat 4-decay accelerating factor (DAF: CD55) inhibits complement-mediated cytolysis but not NK cell-mediated cytolysis.

    PubMed

    Miyagawa, Shuji; Kubo, Tomoko; Matsunami, Katsuyoshi; Kusama, Tamiko; Beppu, Keiko; Nozaki, Hiroshi; Moritan, Toshiyuki; Ahn, Curie; Kim, Jae Young; Fukuta, Daisuke; Shirakura, Ryota

    2004-09-15

    NK cells play a critical role in the rejection of xenografts. In this study, we report on an investigation of the effect of complement regulatory protein, a decay accelerating factor (DAF: CD55), in particular, on NK cell-mediated cytolysis. Amelioration of human NK cell-mediated pig endothelial cell (PEC) and pig fibroblast cell lyses by various deletion mutants and point substitutions of DAF was tested, and compared with their complement regulatory function. Although wild-type DAF and the delta-short consensus repeat (SCR) 1-DAF showed clear inhibition of both complement-mediated and NK-mediated PEC lyses, delta-SCR2-DAF and delta-SCR3-DAF failed to suppress either process. However, delta-SCR4-DAF showed a clear complement regulatory effect, but had no effect on NK cells. Conversely, the point substitution of DAF (L147 x F148 to SS and KKK(125-127) to TTT) was half down-regulated in complement inhibitory function, but the inhibition of NK-mediated PEC lysis remained unchanged. Other complement regulatory proteins, such as the cell membrane-bound form factor H, fH-PI, and C1-inactivator, C1-INH-PI, and CD59 were also assessed, but no suppressive effect on NK cell-mediated PEC lysis was found. These data suggest, for DAF to function on NK cells, SCR2-4 is required but no relation to its complement regulatory function exists.

  18. Profiling of Escherichia coli Chromosome database.

    PubMed

    Yamazaki, Yukiko; Niki, Hironori; Kato, Jun-ichi

    2008-01-01

    The Profiling of Escherichia coli Chromosome (PEC) database (http://www.shigen.nig.ac.jp/ecoli/pec/) is designed to allow E. coli researchers to efficiently access information from functional genomics studies. The database contains two principal types of data: gene essentiality and a large collection of E. coli genetic research resources. The essentiality data are based on data compilation from published single-gene essentiality studies and on cell growth studies of large-deletion mutants. Using the circular and linear viewers for both whole genomes and the minimal genome, users can not only gain an overview of the genome structure but also retrieve information on contigs, gene products, mutants, deletions, and so forth. In particular, genome-wide exhaustive mutants are an essential resource for studying E. coli gene functions. Although the genomic database was constructed independently from the genetic resources database, users may seamlessly access both types of data. In addition to these data, the PEC database also provides a summary of homologous genes of other bacterial genomes and of protein structure information, with a comprehensive interface. The PEC is thus a convenient and useful platform for contemporary E. coli researchers. PMID:18392982

  19. A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles.

    PubMed

    Li, Hongbo; Qiao, Yunfei; Li, Jing; Fang, Hailin; Fan, Dahe; Wang, Wei

    2016-03-15

    Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor. PMID:26436325

  20. Hydrogen plasma reduced black TiO2sbnd B nanowires for enhanced photoelectrochemical water-splitting

    NASA Astrophysics Data System (ADS)

    Tian, Zhangliu; Cui, Huolei; Zhu, Guilian; Zhao, Wenli; Xu, JiJian; Shao, Feng; He, Jianqiao; Huang, Fuqiang

    2016-09-01

    Black TiO2 with various nanostructures and phase constitutions have been reported to exhibit excellent photocatalytic and photoelectrochemical (PEC) performance. Here, we report the fabrication of black nanostructured TiO2sbnd B through hydrogen plasma assisted reduction and its enhanced PEC properties for the first time. Both the obtained TiO2sbnd B and black TiO2sbnd B are single crystalline nanowires, while the black TiO2sbnd B samples exhibit much stronger visible and infrared light absorption. The optimal black TiO2sbnd B sample obtained by hydrogen plasma treatment at 425 °C yields a photocurrent density of 0.85 mA cm-2, a rather low onset potential of -0.937 VAg/AgCl and a high applied bias photon-to-current efficiency (ABPE) of 0.363%, which is far superior to the TiO2sbnd B (0.15 mA cm-2 photocurrent, -0.917 VAg/AgCl onset potential and 0.138% ABPE). The significantly enhanced PEC performance of the black TiO2sbnd B is ascribed to the introduction of moderate surface oxygen vacancies. These results indicate that the black TiO2sbnd B is a promising material for PEC application and solar energy utilization.

  1. Changes in Strength Abilities of Adolescent Girls: The Effect of a 3-Year Physical Education Curriculum

    ERIC Educational Resources Information Center

    Czarniecka, Renata; Milde, Katarzyna; Tomaszewski, Pawel

    2012-01-01

    Study aim: To evaluate changes in strength abilities of adolescent girls that underwent a 3-year physical education curriculum. Material and methods: The research participants comprised 141 girls aged 13.3 plus or minus 0.35 years who participated in a 3-year physical education curriculum (PEC). Evaluation was based on the following EUROFIT…

  2. Detection, isolation and characterization of turkey-origin rotaviruses present in commercial flocks in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poultry enteric syndromes such as poult enteritis complex (PEC) are widespread in the United States. Analysis of intestinal contents from flocks showing signs of enteric disease often reveals infections with numerous suspect viruses. The complex nature of these infections makes laboratory diagnosis ...

  3. Isolation and molecular characterization of avian rotaviruses originally detected in enteric samples collected from commercial turkey flocks.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poultry enteric syndromes such as poult enteritis complex (PEC) and poult enteritis mortality syndrome (PEMS) in young turkeys, and runting-stunting syndrome (RSS) in broiler chickens, are continuous, often seasonal problems for poultry producers in the United States. The specific etiologies of each...

  4. Identification and evaluation of computer models for predicting environmental concentrations of pharmaceuticals and veterinary products in the Nordic environment.

    PubMed

    Wajsman, David; Rudén, Christina

    2006-01-01

    According to European Union Council directive 2001/83, an application for the marketing authorization of a medicinal product shall be accompanied by an environmental risk assessment, including an exposure assessment. Computerized exposure models constitute an important tool in predicting environmental exposure to substances yet to be introduced on the market. This paper reports the process of identifying appropriate exposure models for estimating PECs (Predicted Environmental Concentrations) for pharmaceuticals and veterinary products, focusing on emissions to Swedish aquatic and terrestrial environments via water and sludge from sewage treatment plants. From a large number of information sources, a set of 181 potentially relevant exposure models was identified. A process of scrutinizing and testing these models resulted in a final selection of two models, namely SimpleTreat 3.1 that is used to estimate distribution and elimination of chemicals in sewage treatment plants (resulting in a PEC), and VetPec, suited for veterinary products, that estimates PEC in soil (including pore water), groundwater, and surface water. It is concluded that there is still potential for further development of exposure model(s) specifically designed for pharmaceutical emissions to the Nordic environment and climate. Furthermore, increased regulatory data requirements would facilitate the use of existing models, and improve the quality of the output data from these models. PMID:16030525

  5. Comparative metagenomic analyses of the poultry enteric virome: implications for diagnostics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous comparative metagenomic analyses of the viral communities present in the poultry gut have revealed novel enteric viruses that may affect the overall performance of birds or that may play roles in disease syndromes such as Runting-Stunting Syndrome (RSS) or Poult Enteritis Complex (PEC). Ou...

  6. Plasmonic Pd Nanoparticle- and Plasmonic Pd Nanorod-Decorated BiVO4 Electrodes with Enhanced Photoelectrochemical Water Splitting Efficiency Across Visible-NIR Region

    NASA Astrophysics Data System (ADS)

    Yang, Weiwei; Xiong, Yunjie; Zou, Liangliang; Zou, Zhiqing; Li, Dongdong; Mi, Qixi; Wang, Yanshan; Yang, Hui

    2016-06-01

    The photoelectrochemical (PEC) water splitting performance of BiVO4 is partially hindered by insufficient photoresponse in the spectral region with energy below the band gap. Here, we demonstrate that the PEC water splitting efficiency of BiVO4 electrodes can be effectively enhanced by decorating Pd nanoparticles (NPs) and nanorods (NRs). The results indicate that the Pd NPs and NRs with different surface plasmon resonance (SPR) features delivered an enhanced PEC water splitting performance in the visible and near-infrared (NIR) regions, respectively. Considering that there is barely no absorption overlap between Pd nanostructures and BiVO4 and the finite-difference time domain (FDTD) simulation indicating there are substantial energetic hot electrons in the vicinity of Pd nanostructures, the enhanced PEC performance of Pd NP-decorated BiVO4 and Pd NR-decorated BiVO4 could both benefit from the hot electron injection mechanism instead of the plasmon resonance energy transfer process. Moreover, a combination of Pd NPs and NRs decorated on the BiVO4 electrodes leads to a broad-band enhancement across visible-NIR region.

  7. Systematic approach to in-depth understanding of photoelectrocatalytic bacterial inactivation mechanisms by tracking the decomposed building blocks.

    PubMed

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

    2014-08-19

    A systematic approach was developed to understand, in-depth, the mechanisms involved during the inactivation of bacterial cells using photoelectrocatalytic (PEC) processes with Escherichia coli K-12 as the model microorganism. The bacterial cells were found to be inactivated and decomposed primarily due to attack from photogenerated H2O2. Extracellular reactive oxygen species (ROSs), such as H2O2, may penetrate into the bacterial cell and cause dramatically elevated intracellular ROSs levels, which would overwhelm the antioxidative capacity of bacterial protective enzymes such as superoxide dismutase and catalase. The activities of these two enzymes were found to decrease due to the ROSs attacks during PEC inactivation. Bacterial cell wall damage was then observed, including loss of cell membrane integrity and increased permeability, followed by the decomposition of cell envelope (demonstrated by scanning electronic microscope images). One of the bacterial building blocks, protein, was found to be oxidatively damaged due to the ROSs attacks, as well. Leakage of cytoplasm and biomolecules (bacterial building blocks such as proteins and nucleic acids) were evident during prolonged PEC inactivation process. The leaked cytoplasmic substances and cell debris could be further degraded and, ultimately, mineralized with prolonged PEC treatment.

  8. Enteric viruses of chickens and turkeys

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although enteric disease in commercial poultry operations is common, and often unofficially reported and discussed by field veterinarians as “non-specific enteric disease”, three recognized enteric syndromes do exist in poultry: poult enteritis complex (PEC) and poult enteritis mortality syndrome (P...

  9. COLLABORATIONS THROUGH THE PATHOGEN EQUIVALENCY COMMITTEE HELP ESTABLISH NEW AND EFFECTIVE PROCESSES TO DISINFECT SEWAGE SLUDGE

    EPA Science Inventory

    The focus of this poster will be on the Pathogen Equivalency Committee (PEC) and how, through its collaborative efforts, it supports the US EPA’s requirements for sludge to be properly disinfected prior to its use on land. This is essential to control the spread of infectio...

  10. Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems.

    PubMed

    MacDonald, D D; Ingersoll, C G; Berger, T A

    2000-07-01

    Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R(2) = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems. PMID:10790498

  11. Thin-film photovoltaic cells: long-term metal(loid) leaching at their end-of-life.

    PubMed

    Zimmermann, Yannick-Serge; Schäffer, Andreas; Corvini, Philippe F-X; Lenz, Markus

    2013-11-19

    The photovoltaic effect of thin-film copper indium gallium selenide cells (CIGS) is conferred by the latter elements. Organic photovoltaic cells (OPV), relying on organic light-absorbing molecules, also contain a variety of metals (e.g., Zn, Al, In, Sn, Ag). The environmental impact of such technologies is largely unknown, in particular when the physical integrity deteriorates upon end-of-life, possibly facilitating cell constituent leaching. This study analyzed long-term inorganic leaching from damaged OPV and CIGS into different model waters. Leachate concentrations were put into perspective by calculating the predicted environmental concentrations (PEC) for several scenarios. Roof-top acidic rain runoff from CIGS was found to be the predominant emission source for metals and metalloids, with Cd released to such extents that PEC (173.4 μg Cd L(-1)) would considerably exceed acute toxicity concentrations for Daphnia magna . Other PEC for CIGS (9.9 mg Mo L(-1) and 9.4 μg Se L(-1)) were in the range of teratogenic effects. In contrast, OPV released little metals with calculated PEC being below even conservative drinking water guidelines. Time-resolved single-particle ICP-MS indicated that some metals (Zn, Mo, Ag) were in nanoparticulate form, raising nanotoxicity concerns. Leaching kinetics called for revision of existing standardized (accelerated) leaching protocols because long-term release was most relevant. PMID:24134490

  12. Perception of control over anxiety mediates the relation between catastrophic thinking and social anxiety in social phobia.

    PubMed

    Hofmann, Stefan G

    2005-07-01

    Cognitive models of social phobia (social anxiety disorder) assume that individuals with social phobia experience anxiety in social situations in part because they overestimate the social cost associated with a potentially negative outcome of a social interaction. Some emotion theorists, on the other hand, point to the perception of control over anxiety-related symptoms as a determinant of social anxiety. In order to examine the relationship between perceived emotional control (PEC), estimated social cost (ESC), and subjective anxiety, we compared three alternative structural equation models: Model 1 assumes that PEC and ESC independently predict social anxiety; Model 2 assumes that ESC partially mediates the relationship between PEC and anxiety, and Model 3 assumes that PEC partially mediates the relationship between ESC and anxiety. We recruited 144 participants with social phobia and administered self-report measures of estimated social cost, perceived anxiety control, and social anxiety. The results support Model 3 and suggest that "costly" social situations are anxiety provoking in part because social phobic individuals perceive their anxiety symptoms as being out of control.

  13. Ag nanoclusters could efficiently quench the photoresponse of CdS quantum dots for novel energy transfer-based photoelectrochemical bioanalysis.

    PubMed

    Zhang, Ling; Sun, Yue; Liang, Yan-Yu; He, Jian-Ping; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode, and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface, and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0pM to 10nM and the detection limit was experimentally found to be of 0.3pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development.

  14. Micromachined microbial and photosynthetic fuel cells

    NASA Astrophysics Data System (ADS)

    Chiao, Mu; Lam, Kien B.; Lin, Liwei

    2006-12-01

    This paper presents two types of fuel cells: a miniature microbial fuel cell (µMFC) and a miniature photosynthetic electrochemical cell (µPEC). A bulk micromachining process is used to fabricate the fuel cells, and the prototype has an active proton exchange membrane area of 1 cm2. Two different micro-organisms are used as biocatalysts in the anode: (1) Saccharomyces cerevisiae (baker's yeast) is used to catalyze glucose and (2) Phylum Cyanophyta (blue-green algae) is used to produce electrons by a photosynthetic reaction under light. In the dark, the µPEC continues to generate power using the glucose produced under light. In the cathode, potassium ferricyanide is used to accept electrons and electric power is produced by the overall redox reactions. The bio-electrical responses of µMFCs and µPECs are characterized with the open-circuit potential measured at an average value of 300-500 mV. Under a 10 ohm load, the power density is measured as 2.3 nW cm-2 and 0.04 nW cm-2 for µMFCs and µPECs, respectively.

  15. Synthesis of hollow-structured nano- and microspheres from pectin in a nanodroplet emulsion.

    PubMed

    Reis, Adriano V; Guilherme, Marcos R; Paulino, Alexandre T; Muniz, Edvani C; Mattoso, Luiz H C; Tambourgi, Elias B

    2009-02-17

    Hollow-structured nano- and microspheres with diameters ranging from 24 microm to 160 nm were successfully produced from chemically modified pectin (Ma-Pec) through a two-step synthesis. In a first step, the Pec was modified with glycidyl methacrylate (GMA) in a heterogeneous phase system, indeed consisting of water-soluble Pec and water-insoluble GMA, via an interfacial reaction at the interface of the GMA-water phase system after 12 h under continuous stirring of 1000 rpm at 60 degrees C. In a second step, the spheres were prepared in a water-in-benzyl alcohol nanodroplet emulsion at 12000 rpm under a bubbling stream of nitrogen in the presence of sodium persulfate, as initiator, and TEMED, as catalytic agent. FT-IR spectra revealed that the vinyl groups (CC) coming from the GMA were attached onto backbone of the polysaccharide. 13C-CP/MAS NMR spectra demonstrated that the spheres were formed via carbon-carbon pi-bonds on Ma-Pec in the water phase, for the duration of the dispersion stage. The dark center (an empty core) and edge of the hollow spheres could be easily identified by SEM micrographs. This type of polymer structure represents a class of unique material with particular importance in terms of state-of the-art applications in both nano- and microencapsulation of drugs, for example, protection shields of biologically active agents.

  16. Teaching Young People Who Are Blind and Have Autism to Make Requests Using a Variation on the Picture Exchange Communication System with Tactile Symbols: A Preliminary Investigation

    ERIC Educational Resources Information Center

    Lund, Shelley K.; Troha, Jeanette M.

    2008-01-01

    This study used a single-subject multiple baseline across participants design to evaluate the effectiveness of a modified picture exchange communication system (PECS) teaching protocol with tactile symbols. Three students (two male, one female) aged 12-17 years who had autism and were blind participated in the study. The instructional program…

  17. Effective signal-on photoelectrochemical immunoassay of subgroup J avian leukosis virus based on Bi2S3 nanorods as photosensitizer and in situ generated ascorbic acid for electron donating.

    PubMed

    Sun, Bing; Qiao, Fengmin; Chen, Lijian; Zhao, Zhen; Yin, Huanshun; Ai, Shiyun

    2014-04-15

    A universal and effective photoelectrochemical (PEC) immunosensing device was fabricated on an indium tin oxide (ITO) electrode for sensitive and specific detection of subgroup J of avian leukosis virus (ALVs-J) based on a signal-on strategy. Bismuth sulfide (Bi2S3) nanorods, with good morphology, high crystallinity and differentiated PEC properties, were selected as the photoelectrochemical species and synthesized by a facile hydrothermal method. On the basis of alkaline phosphatase catalytic chemistry to in situ produce ascorbic acid for electron donating, an enhanced photocurrent was obtained. Due to the dependence of the photocurrent signal on the concentration of generated electron donor, an exquisite immunosandwich protocol was successfully constructed for PEC detection of ALVs-J with a linear range from 10(2.14) to 10(3.65) TCID50/mL. The detection limit was 10(2.08) TCID50/mL (S/N=3), and high stability and specificity were obtained. The strategy provides a fast and sensitive method for ALVs-J analysis and opens a general format for future development of PEC immunoanalysis.

  18. Combining Bulk/Surface Engineering of Hematite To Synergistically Improve Its Photoelectrochemical Water Splitting Performance.

    PubMed

    Yuan, Yufei; Gu, Jiuwang; Ye, Kai-Hang; Chai, Zhisheng; Yu, Xiang; Chen, Xiaobo; Zhao, Chuanxi; Zhang, Yuanming; Mai, Wenjie

    2016-06-29

    One of the most promising candidates for photoelectrochemical (PEC) water splitting photoanode is hematite (α-Fe2O3) due to its narrow bandgap and chemical stability. However, the poor bulk/surface kinetics of hematite limits its PEC performance. Herein, a facile two-step approach is reported to synergistically improve the PEC performance of Fe2O3. First, through bulk engineering of Ti doping, the photocurrent density of Ti-Fe2O3 photoanode (1.68 mA cm(-2) at 1.23 VRHE) shows a 3-fold increase compared with that of pure Fe2O3 photoanode (0.50 mA cm(-2) at 1.23 VRHE). Second, the photocurrent density of Ti-Fe2O3 photoanode could be further enhanced to 2.31 mA cm(-2) by surface engineering of FeOOH. The enhanced PEC water splitting performance is proposed to be the synergistic effect of bulk and surface engineering, which can be mainly attributed to the great increase of charge separation efficiency and surface transfer efficiency.

  19. Facile Fabrication of Sandwich Structured WO3 Nanoplate Arrays for Efficient Photoelectrochemical Water Splitting.

    PubMed

    Feng, Xiaoyang; Chen, Yubin; Qin, Zhixiao; Wang, Menglong; Guo, Liejin

    2016-07-20

    Herein, sandwich structured tungsten trioxide (WO3) nanoplate arrays were first synthesized for photoelectrochemical (PEC) water splitting via a facile hydrothermal method followed by an annealing treatment. It was demonstrated that the annealing temperature played an important role in determining the morphology and crystal phase of the WO3 film. Only when the hydrothermally prepared precursor was annealed at 500 °C could the sandwich structured WO3 nanoplates be achieved, probably due to the crystalline phase transition and increased thermal stress during the annealing process. The sandwich structured WO3 photoanode exhibited a photocurrent density of 1.88 mA cm(-2) and an incident photon-to-current conversion efficiency (IPCE) as high as 65% at 400 nm in neutral Na2SO4 solution under AM 1.5G illumination. To our knowledge, this value is one of the best PEC performances for WO3 photoanodes. Meanwhile, simultaneous hydrogen and oxygen evolution was demonstrated for the PEC water splitting. It was concluded that the high PEC performance should be attributed to the large electrochemically active surface area and active monoclinic phase. The present study can provide guidance to develop highly efficient nanostructured photoelectrodes with the favorable morphology.

  20. Plasmonic Pd Nanoparticle- and Plasmonic Pd Nanorod-Decorated BiVO4 Electrodes with Enhanced Photoelectrochemical Water Splitting Efficiency Across Visible-NIR Region.

    PubMed

    Yang, Weiwei; Xiong, Yunjie; Zou, Liangliang; Zou, Zhiqing; Li, Dongdong; Mi, Qixi; Wang, Yanshan; Yang, Hui

    2016-12-01

    The photoelectrochemical (PEC) water splitting performance of BiVO4 is partially hindered by insufficient photoresponse in the spectral region with energy below the band gap. Here, we demonstrate that the PEC water splitting efficiency of BiVO4 electrodes can be effectively enhanced by decorating Pd nanoparticles (NPs) and nanorods (NRs). The results indicate that the Pd NPs and NRs with different surface plasmon resonance (SPR) features delivered an enhanced PEC water splitting performance in the visible and near-infrared (NIR) regions, respectively. Considering that there is barely no absorption overlap between Pd nanostructures and BiVO4 and the finite-difference time domain (FDTD) simulation indicating there are substantial energetic hot electrons in the vicinity of Pd nanostructures, the enhanced PEC performance of Pd NP-decorated BiVO4 and Pd NR-decorated BiVO4 could both benefit from the hot electron injection mechanism instead of the plasmon resonance energy transfer process. Moreover, a combination of Pd NPs and NRs decorated on the BiVO4 electrodes leads to a broad-band enhancement across visible-NIR region.

  1. Augmentative and Alternative Communication in Autism: A Comparison of the Picture Exchange Communication System and Speech-Output Technology

    ERIC Educational Resources Information Center

    Boesch, Miriam Chacon

    2011-01-01

    The purpose of this comparative efficacy study was to investigate the Picture Exchange Communication System (PECS) and a speech-generating device (SGD) in developing requesting skills, social-communicative behavior, and speech for three elementary-age children with severe autism and little to no functional speech. Requesting was selected as the…

  2. Facet cutting and hydrogenation of In(2)O(3) nanowires for enhanced photoelectrochemical water splitting.

    PubMed

    Meng, Ming; Wu, Xinglong; Zhu, Xiaobin; Zhu, Xiaoshu; Chu, Paul K

    2014-03-26

    Semiconductor nanowires (NWs) are useful building blocks in optoelectronic, sensing, and energy devices and one-dimensional NWs have been used in photoelectrochemical (PEC) water splitting because of the enhanced light absorption and charge transport. It has been theoretically predicted that the {001} facets of body center cubic (bcc) In2O3 nanocrystals can effectively accumulate photogenerated holes under illumination, but it is unclear whether facet cutting of NWs can enhance the efficiency of PEC water splitting. In this work, the photocurrent of square In2O3 NWs with four {001} facets is observed to be an order of magnitude larger than that of cylindrical In2O3 NWs under the same conditions and subsequent hydrogen treatment further promotes the PEC water splitting performance of the NWs. The optimized hydrogenated In2O3 NWs yield a photocurrent density of 1.2 mA/cm(2) at 0.22 V versus Ag/AgCl with a Faradaic efficiency of about 84.4%. The enhanced PEC properties can be attributed to the reduced band gap due to merging of the disordered layer-induced band tail states with the valence band as well as improved separation of the photogenerated electrons/holes between the In2O3 crystal core and disordered layer interface. The results provide experimental evidence of the important role of facet cutting, which is promising in the design and fabrication of NW-based photoelectric devices. PMID:24568166

  3. The Use of Video Modeling with the Picture Exchange Communication System to Increase Independent Communicative Initiations in Preschoolers with Autism and Developmental Delays

    ERIC Educational Resources Information Center

    Cihak, David F.; Smith, Catherine C.; Cornett, Ashlee; Coleman, Mari Beth

    2012-01-01

    The use of video modeling (VM) procedures in conjunction with the picture exchange communication system (PECS) to increase independent communicative initiations in preschool-age students was evaluated in this study. The four participants were 3-year-old children with limited communication skills prior to the intervention. Two of the students had…

  4. Three Decades of Peace Education around the World: An Anthology. Garland Reference Library of Social Science, Volume 600. Reference Books in International Education, Volume 24.

    ERIC Educational Resources Information Center

    Burns, Robin J., Ed.; Aspeslagh, Robert, Ed.

    The Peace Education Commission (PEC) of the International Peace Research Association (IPRA) has been the forum for peace educators to come together, to exchange and to share ideas, materials and experiences over three decades. This book draws from key papers from different areas and times of peace education work to show the richness of ideas and…

  5. Virulence potential for extraintestinal infections among commensal Escherichia coli isolated from healthy humans--the Trojan horse within our gut.

    PubMed

    Starčič Erjavec, Marjanca; Žgur-Bertok, Darja

    2015-03-01

    Previous investigations have indicated that the reservoir of extraintestinal pathogenic Escherichia coli (ExPEC) strains is the intestinal microbiota. Nevertheless, studies focused on the prevalence of potential ExPEC strains among the bowel microbiota in healthy human individuals practically do not exist and a strong bias towards pathogenic strains among the E. coli data set is obvious. To assess the prevalence of potential ExPEC strains among E. coli from the intestinal microbiota of healthy humans, we performed a search for data on the prevalence of virulence-associated genes and pathogenicity islands among fecal E. coli found in published studies, including studies comparing isolates from patients suffering from extraintestinal E. coli infections with E. coli from feces of healthy humans. An extensive literature search, including more than 500 published papers, revealed 24 papers with data on prevalences of ≥ 5 virulence-associated genes among 21 E. coli collections including ≥ 20 fecal/rectal strains obtained from healthy individuals and 4 papers with prevalences of pathogenicity islands among E. coli collections from healthy humans. The gathered data are presented in this minireview and clearly show that potential ExPEC strains are present among fecal isolates with a prevalence of around ≥ 10%.

  6. PATHOGEN EQUIVALENCY COMMITTEE UPDATE: PFRP EQUIVALENCY DETERMINATIONS

    EPA Science Inventory

    This presentation will:

    Review the mandate of the Pathogen Equivalency Committee
    Review the PEC's current membership of 10
    Discuss how a typical application is evaluated
    Note where information can be found
    List present deliberations/applications and describe t...

  7. Enhanced photoelectrocatalytic performance of α-Fe2O3 thin films by surface plasmon resonance of Au nanoparticles coupled with surface passivation by atom layer deposition of Al2O3

    NASA Astrophysics Data System (ADS)

    Liu, Yuting; Xu, Zhen; Yin, Min; Fan, Haowen; Cheng, Weijie; Lu, Linfeng; Song, Ye; Ma, Jing; Zhu, Xufei

    2015-09-01

    The short lifetime of photogenerated charge carriers of hematite (α-Fe2O3) thin films strongly hindered the PEC performances. Herein, α-Fe2O3 thin films with surface nanowire were synthesized by electrodeposition and post annealing method for photoelectrocatalytic (PEC) water splitting. The thickness of the α-Fe2O3 films can be precisely controlled by adjusting the duration of the electrodeposition. The Au nanoparticles (NPs) and Al2O3 shell by atom layer deposition were further introduced to modify the photoelectrodes. Different constructions were made with different deposition orders of Au and Al2O3 on Fe2O3 films. The Fe2O3-Au-Al2O3 construction shows the best PEC performance with 1.78 times enhancement by localized surface plasmon resonance (LSPR) of NPs in conjunction with surface passivation of Al2O3 shells. Numerical simulation was carried out to investigate the promotion mechanisms. The high PEC performance for Fe2O3-Au-Al2O3 construction electrode could be attributed to the Al2O3 intensified LSPR, effective surface passivation by Al2O3 coating, and the efficient charge transfer due to the Fe2O3-Au Schottky junctions.

  8. Ultrasensitive photoelectrochemical determination of chromium(VI) in water samples by ion-imprinted/formate anion-incorporated graphitic carbon nitride nanostructured hybrid.

    PubMed

    Fang, Tian; Yang, Xiaomin; Zhang, Lizhi; Gong, Jingming

    2016-07-15

    A rapid and highly sensitive photoelectrochemical (PEC) method has been proposed for the determination of trace amounts of chromium in water samples under visible-light irradiation. Here, a unique nanostructured hybrid of formate anion incorporated graphitic carbon nitride (F-g-C3N4) is smartly integrated with a Cr(VI) ion-imprinted polymer (IIP) as a photoactive electrode (denoted as IIP@F-g-C3N4). The nanohybrid of F-g-C3N4 exhibits an enhanced charge separation with substantially improved PEC responses versus g-C3N4. The newly designed IIP@F-g-C3N4 PEC sensor exhibits high sensitivity and selectivity for the determination of Cr(VI) because it offers efficient photogenerated electron reduction toward Cr(VI). The PEC analysis is highly linear over Cr(VI) concentrations ranging from 0.01 to 100.00ppb with a detection limit of 0.006ppb (S/N=3). Our approach can be used to detect Cr(VI), Cr(III) and the total chromium level in aqueous solution through oxidation of Cr(III) to Cr(VI) and the determination of the total chromium as Cr(VI). In practical applications, this low-cost and sensitive assay has been successfully applied for speciation determination of chromium in environmental water samples.

  9. Exploring the Nature of the H[subscript 2] Bond. 2. Using Ab Initio Molecular Orbital Calculations to Obtain the Molecular Constants

    ERIC Educational Resources Information Center

    Halpern, Arthur M.; Glendening, Eric D.

    2013-01-01

    A project for students in an upper-level course in quantum or computational chemistry is described in which they are introduced to the concepts and applications of a high quality, ab initio treatment of the ground-state potential energy curve (PEC) for H[subscript 2] and D[subscript 2]. Using a commercial computational chemistry application and a…

  10. Production of Hydrogen for Clean and Renewable Source of Energy for Fuel Cell Vehicles

    SciTech Connect

    Deng, Xunming; Ingler, William B, Jr.; Abraham, Martin; Castellano, Felix; Coleman, Maria; Collins, Robert; Compaan, Alvin; Giolando, Dean; Jayatissa, Ahalapitiya. H.; Stuart, Thomas; Vonderembse, Mark

    2008-10-31

    This was a two-year project that had two major components: 1) the demonstration of a PV-electrolysis system that has separate PV system and electrolysis unit and the hydrogen generated is to be used to power a fuel cell based vehicle; 2) the development of technologies for generation of hydrogen through photoelectrochemical process and bio-mass derived resources. Development under this project could lead to the achievement of DOE technical target related to PEC hydrogen production at low cost. The PEC part of the project is focused on the development of photoelectrochemical hydrogen generation devices and systems using thin-film silicon based solar cells. Two approaches are taken for the development of efficient and durable photoelectrochemical cells; 1) An immersion-type photoelectrochemical cells (Task 3) where the photoelectrode is immersed in electrolyte, and 2) A substrate-type photoelectrochemical cell (Task 2) where the photoelectrode is not in direct contact with electrolyte. Four tasks are being carried out: Task 1: Design and analysis of DC voltage regulation system for direct PV-to-electrolyzer power feed Task 2: Development of advanced materials for substrate-type PEC cells Task 3: Development of advanced materials for immersion-type PEC cells Task 4: Hydrogen production through conversion of biomass-derived wastes

  11. Energetics at the Surface of Photoelectrodes and Its Influence on the Photoelectrochemical Properties.

    PubMed

    Thorne, James E; Li, Song; Du, Chun; Qin, Gaowu; Wang, Dunwei

    2015-10-15

    Photoelectrochemistry (PEC) holds potential as a direct route for solar energy storage. Its performance is governed by how efficiently photoexcited charges are separated and how fast the charges are transferred to the solution, both of which are highly sensitive to the photoelectrode surfaces near the electrolyte. While other aspects of a PEC system, such as the light-absorbing materials and the catalysts that facilitate charge transfer, have been extensively examined in the past, an underwhelming amount of attention has been paid to the energetics at the photoelectrode/electrolyte interface. The lack of understanding of this interface is an important reason why many photoelectrode materials fail to deliver the expected performance in harvesting solar energy in a PEC system. Using hematite (α-Fe2O3) as a material platform, we present in this Perspective how surface modifications can alter the energetics and the resulting consequences on the overall PEC performance. It has been shown that a detailed understanding of the photoelectrode/eletrolyte interfaces can contribute significantly to improving the performance of hematite, which enabled unassisted solar water splitting when combined with an amorphous Si photocathode.

  12. Development of two simplified geochemical models for permeability evolution due to calcite dissolution in preferential pathways in caprock

    NASA Astrophysics Data System (ADS)

    Guo, B.; Fitts, J. P.; Peters, C. A.

    2014-12-01

    Leakage through faults and fractures in caprocks is a major concern for geologic carbon sequestration in deep saline aquifers. Current leakage models assume constant permeabilities of pathways, but CO2-acidified brine may cause minerals to dissolve, leading to permeability alteration. Calcite could cause significant permeability alteration, because it is abundant, thermodynamically unstable at low pH, and kinetically fast-reacting. We developed two simplified geochemical models to describe Permeability Evolution due to Calcite dissolution (PEC) in 1D flow paths through caprocks. The first is a numerical reactive transport model that couples solute advection and diffusion with carbonate reactions. The PEC model was used to examine geochemical and mineralogical conditions that lead to extensive permeability alterations. It was found that formations with larger amounts of calcite ultimately have larger final permeabilities, but the change is slower because extensive calcite dissolution buffers the reaction and retards the advance of the dissolution front. The second model, PEC Reaction Progress (PECRP), is a semi-analytical model developed to replicate the predictions of the PEC model but with much shorter run times. The PECRP model is based on assumptions of spatial homogeneity, sharp reacting front, and no reactions above the front. We simulated a synthetic system, the Eau Claire formation, and a sandstone in the Paris Basin to assess PECRP model performance. We found 1) for most cases the PECRP model causes a slightly shorter breakthrough time than the PEC model without affecting the final permeability; 2) when initial porosity is low, we observe temporary permeability decrease in the PEC model, while permeability never decreases in the PECRP model; 3) the PECRP model tends to fail to reproduce results from the PEC model with low Péclet numbers; 4) the PECRP model is not suitable for for pathways with certain types and degrees of mineral spatial heterogeneity. In

  13. A framework for prioritizing fragrance materials for aquatic risk assessment.

    PubMed

    Salvito, Daniel T; Senna, Ronald J; Federle, Thomas W

    2002-06-01

    More than 2,100 chemically defined organic chemicals are listed in the Research Institute of Fragrance Materials/Flavor and Extract Manufacturers' Association (RIFM/FEMA) Database that are used as ingredients of fragrances for consumer products. An approach was developed for prioritizing these fragrance materials for aquatic risk assessment by first estimating the predicted environmental concentration (PEC) of these fragrance materials in the aquatic environment based upon their physicochemical properties and annual volume of use. Subsequently, an effect level was predicted with a general quantitative structure-activity relationship (QSAR) for aquatic toxicity, and a predicted no-effect concentration (PNEC) was calculated from this effect level by using an assessment factor (AF) that accounts for uncertainty in the toxicity QSAR prediction. A conservative AF of 10(6) was applied to the endpoint predicted by the QSAR to provide an adequate margin of safety in the calculation of the PNEC. The PEC was compared to the PNEC to characterize the risk to freshwater aquatic organisms (e.g., Daphnia magna and Pimephales promelas). If the ratio of PEC to PNEC was below one, the material was considered to have negligible environmental risk and to be acceptable for the aquatic environment at current use levels. If this ratio exceeded one, the PNEC was refined by using more specific QSAR models (Ecological Structure-Activity Relationships [ECOSAR]). If the ratio continued to exceed one, the material became a candidate for further aquatic risk assessment procedures, which involve iterative steps to refine the PEC, the PNEC, or both by using measured ecotoxicological endpoints. Prioritization for this latter process can be based upon the magnitudes of the estimated PEC:PNEC ratios. When using the first tier of this approach, only 568 of 2,141 fragrance materials (26.5%) in the RIFM/FEMA Database had PEC:PNEC ratios greater than one. This percentage decreased to only 164 materials

  14. Phase I clinical trial of O-Acetylated pectin conjugate, a plant polysaccharide based typhoid vaccine

    PubMed Central

    Szu, Shousun C.; Lin, Kimi F-Y; Hunt, Steven; Chu, Chiayung; Thinh, Nguyen Duc

    2014-01-01

    Background Typhoid fever remains an important cause of morbidity and mortality in the developing countries. Vi capsular polysaccharide conjugate vaccine demonstrated safety and efficacy in young children in high endemic regions. A novel typhoid conjugate vaccine based on plant polysaccharide pectin was studied in a phase I trial. Methods Fruit pectin, having the same carbohydrate backbone structure as Vi, was purified from citrus peel and used as the polysaccharide source to prepare a semi-synthetic typhoid conjugate vaccine. Pectin was chemically O-acetylated (OAcPec) to antigenically resemble Vi and conjugated to carrier protein rEPA, a recombinant exoprotein A from Pseudomonas aeruginosa. 25 healthy volunteers, 18–45 years old, were injected once with OAcPec-rEPA. Safety and IgG antibodies reactive with Vi and pectin were analyzed. Results No vaccine associated serious adverse reaction was reported. Six weeks after the injection of OAcPec-rEPA, 64% of the volunteers elicited >4 fold rise of anti-Vi IgG. At 26 weeks the level declined, but the difference between the levels at 6 and 26 weeks are not statistically significant. There is a direct correlation between the level of anti-Vi IgG before and after the injection (R2 = 0.96). The anti-Vi IgG can be absorbed by Vi, but not by pectin. There was no corresponding increase of anti-pectin after the injection, indicating the antibody response to OAcPec-rEPA was specific to Vi. There is no Vi-rEPA data in US adults for comparison of immune responses. The OAcPec-rEPA elicited significantly less IgG anti-Vi in US adults than those by Vi-rEPA in Vietnamese adults. Conclusion The O-acetylated pectin conjugate, a plant based typhoid vaccine, is safe and immunogenic in adult volunteers. PMID:24657719

  15. Human-associated fluoroquinolone-resistant Escherichia coli clonal lineages, including ST354, isolated from canine feces and extraintestinal infections in Australia.

    PubMed

    Guo, SiYu; Wakeham, David; Brouwers, Huub J M; Cobbold, Rowland N; Abraham, Sam; Mollinger, Joanne L; Johnson, James R; Chapman, Toni A; Gordon, David M; Barrs, Vanessa R; Trott, Darren J

    2015-04-01

    Phylogenetic group D extraintestinal pathogenic Escherichia coli (ExPEC), including O15:K52:H1 and clonal group A, have spread globally and become fluoroquinolone-resistant. Here we investigated the role of canine feces as a reservoir of these (and other) human-associated ExPEC and their potential as canine pathogens. We characterized and compared fluoroquinolone-resistant E. coli isolates originally identified as phylogenetic group D from either the feces of hospitalized dogs (n = 67; 14 dogs) or extraintestinal infections (n = 53; 33 dogs). Isolates underwent phylogenetic grouping, random amplified polymorphic DNA (RAPD) analysis, virulence genotyping, resistance genotyping, human-associated ExPEC O-typing, and multi-locus sequence typing. Five of seven human-associated sequence types (STs) exhibited ExPEC-associated O-types, and appeared in separate RAPD clusters. The largest subgroup (16 fecal, 26 clinical isolates) were ST354 (phylogroup F) isolates. ST420 (phylogroup B2); O1-ST38, O15:K52:H1-ST393, and O15:K1-ST130 (phylogroup D); and O7-ST457, and O1-ST648 (phylogroup F) were also identified. Three ST-specific RAPD sub-clusters (ST354, ST393, and ST457) contained closely related isolates from both fecal or clinical sources. Genes encoding CTX-M and AmpC β-lactamases were identified in isolates from five STs. Major human-associated fluoroquinolone-resistant ± extended-spectrum cephalosporin-resistant ExPEC of public health importance may be carried in dog feces and cause extraintestinal infections in some dogs.

  16. Microcalorimetry Study of the Adsorption of Asphaltenes and Asphaltene Model Compounds at the Liquid-Solid Surface.

    PubMed

    Pradilla, Diego; Subramanian, Sreedhar; Simon, Sébastien; Sjöblom, Johan; Beurroies, Isabelle; Denoyel, Renaud

    2016-07-26

    The adsorption of an acidic polyaromatic asphaltene model compound (C5PeC11) and indigenous C6-asphaltenes onto the liquid-solid surface is studied. Model compound C5PeC11 exhibits a similar type of adsorption with a plateau adsorbed amount as C6-asphaltenes onto three surfaces (silica, calcite, and stainless steel). Model compound BisAC11, with aliphatic end groups and no acidic functionality, does not adsorb at the liquid-silica surface, indicating the importance of polar interactions on adsorption. The values of the adsorption enthalpy characterized by the ΔHz parameter (the enthalpy at zero coverage) indicate that the type of adsorption and the driving force depend on the surface, a key feature when discussing asphaltene deposition. The adsorption of C5PeC11 onto silica is shown to be driven primarily by H bonding (ΔHz = -34.9 kJ/mol), unlike adsorption onto calcite where polar van der Waals and acidic/basic interactions are thought to be predominant (ΔHz = -23.5 kJ/mol). Interactions between C5PeC11 and stainless steel are found to be weak (ΔHz = -7.7 kJ/mol). Comparing C6-asphaltenes and their esterified counterpart shows that adsorption at the liquid-solid surface is not influenced by the formation of H bonds. This was evidenced by the similar adsorbed amounts obtained. Finally, C5PeC11 captures, to a certain extent, the adsorption interactions of asphaltenes present at the calcite-oil and stainless steel-oil surfaces.

  17. Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils.

    PubMed

    Christiansen, Karen S; Borggaard, Ole K; Holm, Peter E; Vijver, Martina G; Hauschild, Michael Z; Peijnenburg, Willie J G M

    2015-04-01

    Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87% of the pEC50(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

  18. Preparation and evaluation of lipid polymer nanoparticles for eradicating H. pylori biofilm and impairing antibacterial resistance in vitro.

    PubMed

    Cai, Jie; Huang, Huizhi; Song, Weijuan; Hu, Haiyan; Chen, Jiesi; Zhang, Liyan; Li, Pengyu; Wu, Rui; Wu, Chuanbin

    2015-11-30

    The resistance of Helicobacter pylori to classical antimicrobial treatment has become increasingly common, whereupon biofilms are considered to play an important role in the resistance mechanism. Here 10.2% of amoxicillin (AMX) and a novel anti H. pylori adhesion material pectin sulfate (PECS) loaded lipid polymer nanoparticles (LPN) were prepared, with rhamnolipid and phospholipids as the outer mixed lipids layer (RHL-PC-LPN). The size of RHL-PC-LPN was around 200 nm, was negatively-charged, and showed sustained and complete drug release within 24h. In an in vitro study, H. pylori biofilm models were successfully established. RHL-PC-LPN, superior to PC-LPN (employing phospholipids only as the outer lipid layer), PECS+AMX (mixture of PECS and AMX) and AMX only, was proven to significantly eradicate H. pylori in the biofilm form. In accordance to our previous results, the RHL-PC-LPN group, together with the PC-LPN and PECS+AMX group, inhibited H. pylori from adhering to AGS cells. Investigating the underlying mechanisms contributing to the death of H. pylori caused by RHL-PC-LPN, we found that LPN could lower the antibiotic minimal inhibition concentration (MIC) to biofilm form from 125 μg/ml to 15.6 μg/ml. Furthermore, FITC-ConA labeled extracellular polymeric substances (EPS) were decreased in the RHL-PC-LPN group observed by a laser scanning confocal microscope. Therefore, we conclude that employing the mixed lipids of rhamnolipid and phospholipids as the outer layer of nanoparticles and PECS as the inner core produces a system capable of significantly disrupting H. pylori biofilm by eliminating the EPS as well as inhibiting the adherence and colonization of bacteria.

  19. Microcalorimetry Study of the Adsorption of Asphaltenes and Asphaltene Model Compounds at the Liquid-Solid Surface.

    PubMed

    Pradilla, Diego; Subramanian, Sreedhar; Simon, Sébastien; Sjöblom, Johan; Beurroies, Isabelle; Denoyel, Renaud

    2016-07-26

    The adsorption of an acidic polyaromatic asphaltene model compound (C5PeC11) and indigenous C6-asphaltenes onto the liquid-solid surface is studied. Model compound C5PeC11 exhibits a similar type of adsorption with a plateau adsorbed amount as C6-asphaltenes onto three surfaces (silica, calcite, and stainless steel). Model compound BisAC11, with aliphatic end groups and no acidic functionality, does not adsorb at the liquid-silica surface, indicating the importance of polar interactions on adsorption. The values of the adsorption enthalpy characterized by the ΔHz parameter (the enthalpy at zero coverage) indicate that the type of adsorption and the driving force depend on the surface, a key feature when discussing asphaltene deposition. The adsorption of C5PeC11 onto silica is shown to be driven primarily by H bonding (ΔHz = -34.9 kJ/mol), unlike adsorption onto calcite where polar van der Waals and acidic/basic interactions are thought to be predominant (ΔHz = -23.5 kJ/mol). Interactions between C5PeC11 and stainless steel are found to be weak (ΔHz = -7.7 kJ/mol). Comparing C6-asphaltenes and their esterified counterpart shows that adsorption at the liquid-solid surface is not influenced by the formation of H bonds. This was evidenced by the similar adsorbed amounts obtained. Finally, C5PeC11 captures, to a certain extent, the adsorption interactions of asphaltenes present at the calcite-oil and stainless steel-oil surfaces. PMID:27348137

  20. Differential Redox Regulation of Ca2+ Signaling and Viability in Normal and Malignant Prostate Cells

    PubMed Central

    Holzmann, Christian; Kilch, Tatiana; Kappel, Sven; Dörr, Kathrin; Jung, Volker; Stöckle, Michael; Bogeski, Ivan; Peinelt, Christine

    2015-01-01

    In prostate cancer, reactive oxygen species (ROS) are elevated and Ca2+ signaling is impaired. Thus, several novel therapeutic strategies have been developed to target altered ROS and Ca2+ signaling pathways in prostate cancer. Here, we investigate alterations of intracellular Ca2+ and inhibition of cell viability caused by ROS in primary human prostate epithelial cells (hPECs) from healthy tissue and prostate cancer cell lines (LNCaP, DU145, and PC3). In hPECs, LNCaP and DU145 H2O2 induces an initial Ca2+ increase, which in prostate cancer cells is blocked at high concentrations of H2O2. Upon depletion of intracellular Ca2+ stores, store-operated Ca2+ entry (SOCE) is activated. SOCE channels can be formed by hexameric Orai1 channels; however, Orai1 can form heteromultimers with its homolog, Orai3. Since the redox sensor of Orai1 (Cys-195) is absent in Orai3, the Orai1/Orai3 ratio in T cells determines the redox sensitivity of SOCE and cell viability. In prostate cancer cells, SOCE is blocked at lower concentrations of H2O2 compared with hPECs. An analysis of data from hPECs, LNCaP, DU145, and PC3, as well as previously published data from naive and effector TH cells, demonstrates a strong correlation between the Orai1/Orai3 ratio and the SOCE redox sensitivity and cell viability. Therefore, our data support the concept that store-operated Ca2+ channels in hPECs and prostate cancer cells are heteromeric Orai1/Orai3 channels with an increased Orai1/Orai3 ratio in cells derived from prostate cancer tumors. In addition, ROS-induced alterations in Ca2+ signaling in prostate cancer cells may contribute to the higher sensitivity of these cells to ROS. PMID:26445441

  1. HLA-G1, but Not HLA-G3, Suppresses Human Monocyte/Macrophage-mediated Swine Endothelial Cell Lysis.

    PubMed

    Eguchi, H; Maeda, A; Lo, P C; Matsuura, R; Esquivel, E L; Asada, M; Sakai, R; Nakahata, K; Yamamichi, T; Umeda, S; Deguchi, K; Ueno, T; Okuyama, H; Miyagawa, S

    2016-05-01

    The inhibitory function of HLA-G1, a class Ib molecule, on monocyte/macrophage-mediated cytotoxicity was examined. The expression of inhibitory receptors that interact with HLA-G, immunoglobulin-like transcript 2 (ILT2), ILT4, and KIR2DL4 (CD158d) on in vitro-generated macrophages obtained from peripheral blood mononuclear cells and the phorbol 12-myristate 13-acetate (PMA)-activated THP-1 cells were examined by flow cytometry. cDNAs of HLA-G1, HLA-G3, HLA-E, and human β2-microglobulin were prepared, transfected into pig endothelial cells (PECs), and macrophage- and the THP-1 cell-mediated PEC cytolysis was then assessed. In vitro-generated macrophages expressed not only ILT2 and ILT4 but CD158d as well. The transgenic HLA-G1 on PEC indicated a significant suppression in macrophage-mediated cytotoxicity, which was equivalent to that of transgenic HLA-E. HLA-G1 was clearly expressed on the cell surface of PEC, whereas the levels of HLA-G3 were much lower and remained in the intracellular space. On the other hand, the PMA-activated THP-1 cell was less expressed these inhibitory molecules than in vitro-generated macrophages. Therefore, the HLA-G1 on PECs showed a significant but relatively smaller suppression to THP-1 cell-mediated cytotoxicity compared to in vitro-generated macrophages. These results indicate that by generating HLA-G1, but not HLA-G3, transgenic pigs can protect porcine grafts from monocyte/macrophage-mediated cytotoxicity. PMID:27320605

  2. Using carbon nanotubes-gold nanocomposites to quench energy from pinnate titanium dioxide nanorods array for signal-on photoelectrochemical aptasensing.

    PubMed

    Deng, Wenping; Shen, Lei; Wang, Xiu; Yang, Chunlei; Yu, Jinghua; Yan, Mei; Song, Xianrang

    2016-08-15

    On the basis of the absorption and emission spectra overlap, an enhanced resonance energy transfer caused by excition-plasmon resonance between carbon nanotubes-gold nanoparticles (CNTs-Au) and pinnate titanium dioxide nanorods array (P-TiO2 NA) was obtained. Three-dimensional single crystalline P-TiO2 were prepared successfully on fluorine-doped tin oxide conducting glass (FTO glass), and its optical absorption properties and photoelectrochemical (PEC) properties were investigated. With the synergy of CNTs-Au as energy acceptor, it resulted in the enhancement of energy transfer between excited P-TiO2 NA and CNTs-Au. Upon the novel sandwichlike structure formed via DNA hybridization, the exciton produced in P-TiO2 NA was annihilated and a damped photocurrent was obtained. With the use of carcinoembryonic antigen (CEA) as a model which bonded to its specific aptamer and destroyed the sandwichlike structure, the energy transfer efficiency was lowered, leading to PEC response augment. Thus a signal-on PEC aptasensor was constructed. Under the optimal conditions, the PEC aptasensor for CEA determination exhibited a linear range from 0.001 to 2.5ngmL(-1) with a detection limit of 0.39pgmL(-1) and was satisfactory for clinical sample detection. Furthermore, the proposed aptasensor shows satisfying performance, such as easy preparation, rapid detection and so on. Moreover, since different aptamer can specifically bind to different target molecules, the designed strategy has an expansive application for the construction of versatile PEC platforms.

  3. Prevalence of Avian-Pathogenic Escherichia coli Strain O1 Genomic Islands among Extraintestinal and Commensal E. coli Isolates

    PubMed Central

    Johnson, Timothy J.; Wannemuehler, Yvonne; Kariyawasam, Subhashinie; Johnson, James R.; Logue, Catherine M.

    2012-01-01

    Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include pathogens of humans and animals. Previously, the genome of avian-pathogenic E. coli (APEC) O1:K1:H7 strain O1, from ST95, was sequenced and compared to those of several other E. coli strains, identifying 43 genomic islands. Here, the genomic islands of APEC O1 were compared to those of other sequenced E. coli strains, and the distribution of 81 genes belonging to 12 APEC O1 genomic islands among 828 human and avian ExPEC and commensal E. coli isolates was determined. Multiple islands were highly prevalent among isolates belonging to the O1 and O18 serogroups within phylogenetic group B2, which are implicated in human neonatal meningitis. Because of the extensive genomic similarities between APEC O1 and other human ExPEC strains belonging to the ST95 phylogenetic lineage, its ability to cause disease in a rat model of sepsis and meningitis was assessed. Unlike other ST95 lineage strains, APEC O1 was unable to cause bacteremia or meningitis in the neonatal rat model and was significantly less virulent than uropathogenic E. coli (UPEC) CFT073 in a mouse sepsis model, despite carrying multiple neonatal meningitis E. coli (NMEC) virulence factors and belonging to the ST95 phylogenetic lineage. These results suggest that host adaptation or genome modifications have occurred either in APEC O1 or in highly virulent ExPEC isolates, resulting in differences in pathogenicity. Overall, the genomic islands examined provide targets for further discrimination of the different ExPEC subpathotypes, serogroups, phylogenetic types, and sequence types. PMID:22467781

  4. Immunogenic characterization of outer membrane porins OmpC and OmpF of porcine extraintestinal pathogenic Escherichia coli.

    PubMed

    Liu, Canying; Chen, Zhaohui; Tan, Chen; Liu, Wugang; Xu, Zhuofei; Zhou, Rui; Chen, Huanchun

    2012-12-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen that can cause systemic infections in a broad spectrum of mammals and birds. To date, commercial vaccines against ExPEC infections in pigs are rare and antibiotic resistance has become a serious clinical problem. Identification of protective antigens is helpful for developing potentially effective vaccines. In this study, two outer membrane porins, OmpC and OmpF, of porcine ExPEC were cloned and expressed to investigate their immunogenicity. Intraperitoneal immunization of mice with the purified recombinant proteins OmpC and OmpF stimulated strong immunoglobulin G (IgG) antibody responses. Both IgG1 and IgG2a subclasses were induced, with a predominance of IgG1 production. After challenge with 2.5 × 10(7) CFU (5 × LD50 ) of the highly virulent ExPEC strain PCN033, 62.5% and 87.5% protection was observed in mice immunized with OmpC and OmpF, respectively. In addition, both anti-OmpC and anti-OmpF sera can mediate complement-dependent opsonophagocytosis. Phylogenetic analysis showed that the ompC gene was ubiquitously present in all E. coli strains, whereas the ompF gene was mutated in certain strains. Furthermore, the selection analysis indicated that gene ompC may be subject to strong immune pressure. Our results demonstrated that OmpC is a promising vaccine target against ExPEC infections in swine.

  5. Exposure assessment of 17alpha-ethinylestradiol in surface waters of the United States and Europe.

    PubMed

    Hannah, Robert; D'Aco, Vincent J; Anderson, Paul D; Buzby, Mary E; Caldwell, Daniel J; Cunningham, Virginia L; Ericson, Jon F; Johnson, Andrew C; Parke, Neil J; Samuelian, John H; Sumpter, John P

    2009-12-01

    An evaluation of measured and predicted concentrations of 17-ethinylestradiol in surface waters of the United States and Europe was conducted to develop expected long-term exposure concentrations for this compound. Measured environmental concentrations (MECs) in surface waters were identified from the literature. Predicted environmental concentrations (PECs) were generated for European and U.S. watersheds using the GREAT-ER and PhATE models, respectively. The majority of MECs are nondetect and generally consistent with model PECs and conservative mass balance calculations. However, the highest MECs are not consistent with concentrations derived from conservative (worst-case) mass balance estimates or model PECs. A review of analytical methods suggests that tandem or high-resolution mass spectrometry methods with extract cleanup result in lower detection limits and lower reported concentrations consistent with model predictions and bounding estimates. Based on model results using PhATE and GREAT-ER, the 90th-percentile low-flow PECs in surface water are approximately 0.2 and 0.3 ng/L for the United States and Europe, respectively. These levels represent conservative estimates of long-term exposure that can be used for risk assessment purposes. Our analysis also indicates that average concentrations are one to two orders of magnitude lower than these 90th-percentile estimates. Higher reported concentrations (e.g., greater than the 99th-percentile PEC of approximately 1 ng/L) could result from methodological problems or unusual environmental circumstances; however, such concentrations are not representative of levels generally found in the environment, warrant special scrutiny, and are not appropriate for use in risk assessments of long-term exposures. PMID:19645524

  6. Ion Environments in Mn(2+)-Doped Polyelectrolyte Complexes: Dilute Magnetic Saloplastics.

    PubMed

    Abhyankar, Nandita; Ghoussoub, Yara E; Wang, Qifeng; Dalal, Naresh S; Schlenoff, Joseph B

    2016-07-14

    Amorphous hydrated complexes of the polyelectrolytes poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium) were doped with the spin-5/2 ion Mn(2+). X-band electron paramagnetic resonance (EPR) measurements of the Mn(2+) spins within these stoichiometric polyelectrolyte complexes (PECs) revealed an octahedral coordination environment, similar to that observed in aqueous solutions of Mn(2+). This octahedral symmetry of the [Mn(H2O)6](2+) complexes, observed in fully hydrated PECs, is somewhat distorted because of the wide range of ion pairs possible with the sulfonate group on PSS. As the Mn(2+) concentration was increased, the linewidths broadened, indicating the dominance of dipolar broadening over exchange narrowing in determining the linewidths; that is, any exchange narrowing was masked by the large dipolar broadening. The calculated linewidths were used to estimate the strengths of the dipolar interactions, and hence the distances between the Mn(2+) spins, on the basis of a simple model of regularly spaced spins. The distances calculated by this method were roughly comparable to the geometric average distances calculated on the basis of the Mn(2+) concentrations and densities of the doped PEC samples. From a comparison of their EPR spectra, the ion environments in the doped, fully hydrated PECs were found to be similar to those in hydrated classical ion exchange resins. EPR spectra before and after drying of the PECs indicate the replacement of octahedrally coordinated water by oxide anions from the polyanion chain and the corresponding loss of the symmetric environment of Mn(2+) ions.

  7. Consumption and occurrence of pharmaceutical and personal care products in the aquatic environment in Spain.

    PubMed

    Ortiz de García, Sheyla; Pinto Pinto, Gilberto; García Encina, Pedro; Irusta Mata, Rubén

    2013-02-01

    The occurrence of sixty pharmaceutically active compounds (PhACs), twenty metabolites and eight personal care products (PCPs) in the aquatic environment in Spain and their predicted environmental concentrations (PECs) were calculated and compared with measured environmental concentrations (MECs) obtained from relevant published research. The occurrence in the aquatic environment was calculated through a mass balance approach considering the following: the number of pharmaceutical prescriptions issued, the amount of pharmaceutical discharged without consumption, consumption, self-medication, pharmacokinetics, treatment in wastewater facilities and discharged to aquatic environment. The estimation of consumption of active compounds of pharmaceuticals was conducted by at least one of the following methodologies: number of commercial packages sold, data for the number of defined daily dose per 1000 inhabitants per day (DHD), and pattern of treatment. Comparison of these methodologies for some compounds showed similar estimated consumption ranges. The highest pharmaceutical occurrence in the aquatic environment was for acetaminophen glucuronide, Galaxolide®, Iso-E-super®, acetaminophen, valsartan, amoxicillin, 2-hydroxy-ibuprofen, iopromide, omeprazole, carbamazepine 10, 11-epoxide, iopamidol, salicylic β-d-O-glucuronide acid, Tonalide®, acetylsalicylic acid (ASA), clarithromycin and iohexol, with releases between 5 and 600 ty(-1). The relation of PEC/MEC was calculated for 58% of the compounds under study, and 64.7% of them had PEC/MEC ratios between 0.5 and 2. PEC values were mostly overestimated (57.4%). The predicted concentrations for pharmaceutical and personal care products (PPCPs) that had a high occurrence in the aquatic environment were very close to the measured concentrations. This research provides information that had not been calculated and analyzed previously, at least for Spain. Estimation of the PECs for pharmaceutical, personal care products and

  8. A semiconductor/mixed ion and electron conductor heterojunction for elevated-temperature water splitting.

    PubMed

    Ye, Xiaofei; Melas-Kyriazi, John; Feng, Zhuoluo A; Melosh, Nicholas A; Chueh, William C

    2013-10-01

    Photoelectrochemical cells (PECs) have been studied extensively for dissociating water into hydrogen and oxygen. Key bottlenecks for achieving high solar-to-hydrogen efficiency in PECs include increasing solar spectrum utilization, surmounting overpotential losses, and aligning the absorber/electrochemical redox levels. We propose a new class of solid-state PECs based on mixed ionic and electronic conducting (MIEC) oxides that operates at temperatures significantly above ambient and utilizes both the light and thermal energy available from concentrated sunlight to dissociate water vapor. Unlike thermochemical and hybrid photo-thermochemical water-splitting routes, the elevated-temperature PEC is a single-step approach operating isothermally. At the heart of the solid-state PEC is a semiconductor light absorber coated with a thin MIEC layer for improved catalytic activity, electrochemical stability, and ionic conduction. The MIEC, placed between the gas phase and the semiconductor light absorber, provides a facile path for minority carriers to reach the water vapor as well as a path for the ionic carriers to reach the solid electrolyte. Elevated temperature operation allows reasonable band misalignments at the interfaces to be overcome, reduces the required overpotential, and facilitates rapid product diffusion away from the surface. In this work, we simulate the behavior of an oxygen-ion-conducting photocathode in 1-D. Using the detailed-balance approach, in conjunction with recombination and electrochemical reaction rates, the practical efficiency is calculated as a function of temperature, solar flux, and select material properties. For a non-degenerate light absorber with a 2.0 eV band-gap and an uphill band offset of 0.3 eV, an efficiency of 17% and 11% is predicted at 723 and 873 K, respectively.

  9. Advancing the Chemistry of CuWO4 for Photoelectrochemical Water Oxidation.

    PubMed

    Lhermitte, Charles R; Bartlett, Bart M

    2016-06-21

    Photoelectrochemical (PEC) cells are an ongoing area of exploration that provide a means of converting solar energy into a storable chemical form (molecular bonds). In particular, using PEC cells to drive the water splitting reaction to obtain H2 could provide a clean and sustainable route to convert solar energy into chemical fuels. Since the discovery of catalytic water splitting on TiO2 photoelectrodes by Fujishima and Honda, significant efforts have been directed toward developing high efficiency metal oxides to use as photocatalysts for this reaction. Improving the efficiency of PEC cells requires developing chemically stable, and highly catalytic anodes for the oxygen-evolution reaction (OER). This water oxidation half reaction requires four protons and four electrons coupling in two bond making steps to form O2, which limits the rate. Our group has accelerated efforts in CuWO4 as a candidate for PEC OER chemistry. Its small band gap of 2.3 eV allows for using visible light to drive OER, and the reaction proceeds with a high degree of chemoselectivity, even in the presence of more kinetically accessible anions such as chloride, which is common to seawater. Furthermore, CuWO4 is a chemically robust material when subjected to the highly oxidizing conditions of PEC OER. The next steps for accelerating research using this (and other), ternary phase oxides, is to move beyond reporting the basic PEC measurements to understanding fundamental chemical reaction mechanisms operative during OER on semiconductor surfaces. In this Account, we outline the process for PEC OER on CuWO4 thin films with emphasis on the chemistry of this reaction, the reaction rate and selectivity (determined by controlled-potential coulometry and oxygen-detection experiments). We discuss key challenges with CuWO4 such as slow kinetics and the presence of an OER-mediating mid-gap state, probed by electrochemical impedance spectroscopy. We propose that this mid-gap state imparts the observed

  10. Advancing the Chemistry of CuWO4 for Photoelectrochemical Water Oxidation.

    PubMed

    Lhermitte, Charles R; Bartlett, Bart M

    2016-06-21

    Photoelectrochemical (PEC) cells are an ongoing area of exploration that provide a means of converting solar energy into a storable chemical form (molecular bonds). In particular, using PEC cells to drive the water splitting reaction to obtain H2 could provide a clean and sustainable route to convert solar energy into chemical fuels. Since the discovery of catalytic water splitting on TiO2 photoelectrodes by Fujishima and Honda, significant efforts have been directed toward developing high efficiency metal oxides to use as photocatalysts for this reaction. Improving the efficiency of PEC cells requires developing chemically stable, and highly catalytic anodes for the oxygen-evolution reaction (OER). This water oxidation half reaction requires four protons and four electrons coupling in two bond making steps to form O2, which limits the rate. Our group has accelerated efforts in CuWO4 as a candidate for PEC OER chemistry. Its small band gap of 2.3 eV allows for using visible light to drive OER, and the reaction proceeds with a high degree of chemoselectivity, even in the presence of more kinetically accessible anions such as chloride, which is common to seawater. Furthermore, CuWO4 is a chemically robust material when subjected to the highly oxidizing conditions of PEC OER. The next steps for accelerating research using this (and other), ternary phase oxides, is to move beyond reporting the basic PEC measurements to understanding fundamental chemical reaction mechanisms operative during OER on semiconductor surfaces. In this Account, we outline the process for PEC OER on CuWO4 thin films with emphasis on the chemistry of this reaction, the reaction rate and selectivity (determined by controlled-potential coulometry and oxygen-detection experiments). We discuss key challenges with CuWO4 such as slow kinetics and the presence of an OER-mediating mid-gap state, probed by electrochemical impedance spectroscopy. We propose that this mid-gap state imparts the observed

  11. Occurrence and variability of mining-related lead and zinc in the Spring River flood plain and tributary flood plains, Cherokee County, Kansas, 2009--11

    USGS Publications Warehouse

    Juracek, Kyle E.

    2013-01-01

    Historical mining activity in the Tri-State Mining District (TSMD), located in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma, has resulted in a substantial ongoing input of cadmium, lead, and zinc to the environment. To provide some of the information needed to support remediation efforts in the Cherokee County, Kansas, superfund site, a 4-year study was begun in 2009 by the U.S. Geological Survey that was requested and funded by the U.S. Environmental Protection Agency. A combination of surficial-soil sampling and coring was used to investigate the occurrence and variability of mining-related lead and zinc in the flood plains of the Spring River and several tributaries within the superfund site. Lead- and zinc-contaminated flood plains are a concern, in part, because they represent a long-term source of contamination to the fluvial environment. Lead and zinc contamination was assessed with reference to probable-effect concentrations (PECs), which represent the concentrations above which adverse aquatic biological effects are likely to occur. The general PECs for lead and zinc were 128 and 459 milligrams per kilogram, respectively. The TSMD-specific PECs for lead and zinc were 150 and 2,083 milligrams per kilogram, respectively. Typically, surficial soils in the Spring River flood plain had lead and zinc concentrations that were less than the general PECs. Lead and zinc concentrations in the surficial-soil samples were variable with distance downstream and with distance from the Spring River channel, and the largest lead and zinc concentrations usually were located near the channel. Lead and zinc concentrations larger than the general or TSMD-specific PECs, or both, were infrequent at depth in the Spring River flood plain. When present, such contamination typically was confined to the upper 2 feet of the core and frequently was confined to the upper 6 inches. Tributaries with few or no lead- and zinc-mined areas in the basin—Brush Creek

  12. Analysis and fabrication of tungsten CERMET materials for ultra-high temperature reactor applications via pulsed electric current sintering

    NASA Astrophysics Data System (ADS)

    Webb, Jonathan A.

    The optimized development path for the fabrication of ultra-high temperature W-UO2 CERMET fuel elements were explored within this dissertation. A robust literature search was conducted, which concluded that a W-UO 2 fuel element must contain a fine tungsten microstructure and spherical UO2 kernels throughout the entire consolidation process. Combined Monte Carlo and Computational Fluid Dynamics (CFD) analysis were used to determine the effects of rhenium and gadolinia additions on the performance of W-UO 2 fuel elements at refractory temperatures and in dry and water submerged environments. The computational analysis also led to the design of quasi-optimized fuel elements that can meet thermal-hydraulic and neutronic requirements A rigorous set of experiments were conducted to determine if Pulsed Electric Current Sintering (PECS) can fabricate tungsten and W-Ce02 specimens to the required geometries, densities and microstructures required for high temperature fuel elements as well as determine the mechanisms involved within the PECS consolidation process. The CeO2 acts as a surrogate for UO 2 fuel kernels in these experiments. The experiments seemed to confirm that PECS consolidation takes place via diffusional mass transfer methods; however, the densification process is rapidly accelerated due to the effects of current densities within the consolidating specimen. Fortunately the grain growth proceeds at a traditional rate and the PECS process can yield near fully dense W and W-Ce02 specimens with a finer microstructure than other sintering techniques. PECS consolidation techniques were also shown to be capable of producing W-UO2 segments at near-prototypic geometries; however, great care must be taken to coat the fuel particles with tungsten prior to sintering. Also, great care must be taken to ensure that the particles remain spherical in geometry under the influence of a uniaxial stress as applied during PECS, which involves mixing different fuel kernel sizes in

  13. MRCI study on the spectroscopic parameters and molecular constants of the X 1Σ +, a3Σ +, A 1Π and C 1Σ - electronic states of the SiO molecule

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Li, Wentao; Sun, Jinfeng; Zhu, Zunlue

    2012-02-01

    The potential energy curves (PECs) of the X 1Σ +, a3Σ +, A 1Π and C 1Σ - electronic states of the SiO molecule are studied using an ab initio quantum chemical method. The calculations have been made employing the complete active space self-consistent field (CASSCF) method, which is followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with several correlation-consistent basis sets. The effect on the PECs by the core-valence correlation and relativistic corrections is included. The way to consider the relativistic correction is to use the third-order Douglas-Kroll Hamiltonian approximation. The core-valence correlation correction is carried out with the cc-pCVQZ basis set, and the relativistic correction is performed at the level of the cc-pVQZ basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI + Q). The PECs of these electronic states are extrapolated to the complete basis set limit by the total-energy extrapolation scheme. Employing these PECs, the spectroscopic parameters are calculated and compared with those reported in the literature. With these PECs determined by the MRCI + Q/CV + DK + 56 calculations, by solving the radial Schrödinger equation of nuclear motion, 110 vibrational states for the X 1Σ +, 69 for the a3Σ +, 54 for the A 1Π and 67 for the C 1Σ - electronic state are predicted when the rotational quantum number J equals zero. The vibrational manifolds of the first 20 vibrational states are reported and compared with the available RKR data for each electronic state. On the whole, as expected, the most accurate spectroscopic parameters and molecular constants of the SiO molecule are obtained by the MRCI + Q/CV + DK + 56 calculations. And the present molecular constants of the a3Σ +, C 1Σ - and A 1Π electronic states determined by the MRCI + Q/CV + DK

  14. Evaluation of the Dmt-Tic pharmacophore: conversion of a potent delta-opioid receptor antagonist into a potent delta agonist and ligands with mixed properties.

    PubMed

    Balboni, Gianfranco; Guerrini, Remo; Salvadori, Severo; Bianchi, Clementina; Rizzi, Daniela; Bryant, Sharon D; Lazarus, Lawrence H

    2002-01-31

    Analogues of the 2',6'-dimethyl-L-tyrosine (Dmt)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) pharmacophore were prepared to test the hypothesis that a "spacer" and a third aromatic center in opioid peptides are required to convert a delta-antagonist into ligands with delta-agonist or with mixed delta-antagonist/mu-agonist properties. Potent delta-agonists and bifunctional compounds with high delta- and mu-opioid receptor affinities were obtained by varying the spacer length [none, NH-CH(2), NH-CH(2)-CH(2), Gly-NH-CH(2)] and C-terminal aromatic nucleus [1H-benzimidazole-2-yl, phenyl (Ph) and benzyl groups]. C-terminal modification primarily affected mu-opioid receptor affinities, which increased maximally 1700-fold relative to the prototype delta-antagonist H-Dmt-Tic-NH(2) and differentially modified bioactivity. In the absence of a spacer (1), the analogue exhibited dual delta-agonism (pEC(50), 7.28) and delta-antagonism (pA(2), 7.90). H-Dmt-Tic-NH-CH(2)-1H-benzimidazole-2-yl (Bid) (2) became a highly potent delta-agonist (pEC(50), 9.90), slightly greater than deltorphin C (pEC(50), 9.56), with mu-agonism (pE(50), 7.57), while H-Dmt-Tic-Gly-NH-CH(2)-Bid (4) retained potent delta-antagonism (pA(2), 9.0) but with an order of magnitude less mu-agonism. Similarly, H-Dmt-Tic-Gly-NH-Ph (5) had nearly equivalent high delta-agonism (pEC(50), 8.52) and mu-agonism (pEC(50), 8.59), while H-Dmt-Tic-Gly-NH-CH(2)-Ph (6) whose spacer was longer by a single methylene group exhibited potent delta-antagonism (pA(2), 9.25) and very high mu-agonism (pEC(50), 8.57). These data confirm that the distance between the Dmt-Tic pharmacophore and a third aromatic nucleus is an important criterion in converting Dmt-Tic from a highly potent delta-antagonist into a potent delta-agonist or into ligands with mixed delta- and mu-opioid properties.

  15. Photoelectrochemical Hydrogen Production - Final Report

    SciTech Connect

    Miller, E.L.; Marsen, B.; Paluselli, D.; Rocheleau, R.

    2004-11-17

    The scope of this photoelectrochemical hydrogen research project is defined by multijunction photoelectrode concepts for solar-powered water splitting, with the goal of efficient, stable, and economic operation. From an initial selection of several planar photoelectrode designs, the Hybrid Photoelectrode (HPE) has been identified as the most promising candidate technology. This photoelectrode consists of a photoelectrochemical (PEC) junction and a solid-state photovoltaic (PV) junction. Immersed in aqueous electrolyte and exposed to sunlight, these two junctions provide the necessary voltage to split water into hydrogen and oxygen gas. The efficiency of the conversion process is determined by the performance of the PEC- and the PV-junctions and on their spectral match. Based on their stability and cost effectiveness, iron oxide (Fe2O3) and tungsten oxide (WO3) films have been studied and developed as candidate semiconductor materials for the PEC junction (photoanode). High-temperature synthesis methods, as reported for some high-performance metal oxides, have been found incompatible with multijunction device fabrication. A low-temperature reactive sputtering process has been developed instead. In the parameter space investigated so far, the optoelectronic properties of WO3 films were superior to those of Fe2O3 films, which showed high recombination of photo-generated carriers. For the PV-junction, amorphous-silicon-based multijunction devices have been studied. Tandem junctions were preferred over triple junctions for better stability and spectral matching with the PEC junction. Based on a tandem a-SiGe/a-SiGe device and a tungsten trioxide film, a prototype hybrid photoelectrode has been demonstrated at 0.7% solar-to-hydrogen (STH) conversion efficiency. The PEC junction performance has been identified as the most critical element for higher-efficiency devices. Research into sputter-deposited tungsten trioxide films has yielded samples with higher photocurrents of

  16. Roles of cocatalysts in photocatalysis and photoelectrocatalysis.

    PubMed

    Yang, Jinhui; Wang, Donge; Han, Hongxian; Li, Can

    2013-08-20

    Since the 1970s, splitting water using solar energy has been a focus of great attention as a possible means for converting solar energy to chemical energy in the form of clean and renewable hydrogen fuel. Approaches to solar water splitting include photocatalytic water splitting with homogeneous or heterogeneous photocatalysts, photoelectrochemical or photoelectrocatalytic (PEC) water splitting with a PEC cell, and electrolysis of water with photovoltaic cells coupled to electrocatalysts. Though many materials are capable of photocatalytically producing hydrogen and/or oxygen, the overall energy conversion efficiency is still low and far from practical application. This is mainly due to the fact that the three crucial steps for the water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic reduction and oxidation reactions, are not efficient enough or simultaneously. Water splitting is a thermodynamically uphill reaction, requiring transfer of multiple electrons, making it one of the most challenging reactions in chemistry. This Account describes the important roles of cocatalysts in photocatalytic and PEC water splitting reactions. For semiconductor-based photocatalytic and PEC systems, we show that loading proper cocatalysts, especially dual cocatalysts for reduction and oxidation, on semiconductors (as light harvesters) can significantly enhance the activities of photocatalytic and PEC water splitting reactions. Loading oxidation and/or reduction cocatalysts on semiconductors can facilitate oxidation and reduction reactions by providing the active sites/reaction sites while suppressing the charge recombination and reverse reactions. In a PEC water splitting system, the water oxidation and reduction reactions occur at opposite electrodes, so cocatalysts loaded on the electrode materials mainly act as active sites/reaction sites spatially separated as natural photosynthesis does. In both cases, the nature of the

  17. Carbon quantum dots decorated Cu2S nanowire arrays for enhanced photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Li, Ming; Zhao, Renjie; Su, Yanjie; Yang, Zhi; Zhang, Yafei

    2016-04-01

    The photoelectrochemical (PEC) performance of Cu2S nanowire arrays (NWAs) has been demonstrated to be greatly enhanced by dipping-assembly of carbon quantum dots (CQDs) on the surfaces of Cu2S NWAs. Experimental results show that the pristine Cu2S NWAs with higher aspect ratios exhibit better PEC performance due to the longer length scale for light absorption and the shorter length scale for minority carrier diffusion. Importantly, the CQDs decorated Cu2S NWAs exhibit remarkably enhanced photocurrent density, giving a photocurrent density of 1.05 mA cm-2 at 0 V vs. NHE and an optimal photocathode efficiency of 0.148% under illumination of AM 1.5G (100 mW cm-2), which is 4 times higher than that of the pristine Cu2S NWAs. This can be attributed to the improved electron transfer and the energy-down-shift effect of CQDs. We believe that this inexpensive Cu2S/CQD photocathode with increased photocurrent density opens up new opportunities in PEC water splitting.The photoelectrochemical (PEC) performance of Cu2S nanowire arrays (NWAs) has been demonstrated to be greatly enhanced by dipping-assembly of carbon quantum dots (CQDs) on the surfaces of Cu2S NWAs. Experimental results show that the pristine Cu2S NWAs with higher aspect ratios exhibit better PEC performance due to the longer length scale for light absorption and the shorter length scale for minority carrier diffusion. Importantly, the CQDs decorated Cu2S NWAs exhibit remarkably enhanced photocurrent density, giving a photocurrent density of 1.05 mA cm-2 at 0 V vs. NHE and an optimal photocathode efficiency of 0.148% under illumination of AM 1.5G (100 mW cm-2), which is 4 times higher than that of the pristine Cu2S NWAs. This can be attributed to the improved electron transfer and the energy-down-shift effect of CQDs. We believe that this inexpensive Cu2S/CQD photocathode with increased photocurrent density opens up new opportunities in PEC water splitting. Electronic supplementary information (ESI) available

  18. Investigation of the plasmasphere electron content on the base of radio-measurements

    NASA Astrophysics Data System (ADS)

    Cherniak, I.; Zakharenkova, I.; Krankowski, A.

    2013-12-01

    The electron densities in plasmasphere are several orders of magnitude less than in ionosphere and the plasmasphere is often ignored at analysis and estimation of GPS TEC data, however the plasmaspheric contribution to the GPS TEC can became significant under certain conditions. This paper presents results of study of the plasmaspheric electron content variations for such cases - period of very low solar activity and during strong geomagnetic storm. Estimates of IEC can be retrieved as a result of integration of ionospheric electron density profiles (EDP). For this aim one can use EDPs derived from satellite radio occultation (RO) or ground-based radio-physical measurements. For case of the extended solar minimum of 23/24 cycle, 2009 the PEC was estimated by combination of GPS TEC observations and FORMOSAT-3/COSMIC RO measurements. It was analyzed the monthly medians of TEC and PEC for different seasons (equinoxes and solstices). Results shows that for mid-latitudinal points PEC estimates varied weakly with the time of a day and reached the value of several TECU for the condition of solar minimum. Percentage contribution of PEC to GPS TEC indicated the clear dependence from the time with maximal values (more than 50-60%) during night-time and lesser values (25-45%) during day-time. The variations of PEC during strong geomagnetic storms at November 2004 were estimated by combining of mid-latitude Kharkov Incoherent Scatter Radar observations and GPS TEC data. The comparison between two independent measurements was performed by analysis of the height-temporal distribution for specific point corresponded to the mid-latitudes of Europe. Percentage contribution of PEC to GPS TEC indicated the clear dependence from the time with maximal values (more than 70%) during night-time and smaller values (30-45%) during day-time for weak disturbance and quite time and rather high values during strong negative storm (up to 90%) with small changes in time. These changes can be

  19. Patient experience of care in the safety net: Current efforts and challenges

    PubMed Central

    Zuckerman, Katharine E.; Wong, Alicia; Teleki, Stephanie; Edgman-Levitan, Susan

    2013-01-01

    Measuring the patient’s experience of care (PEC) fosters the delivery of patient-centered services and increases health care quality. Most pay-for-performance and public reporting programs focus on care provided to insured populations, excluding the uninsured. Using qualitative research methods, we interviewed leaders of California safety-net practices to assess how they measure PEC and the measurement barriers they encounter. Most had unmet needs for assistance with data collection and quality improvement strategies for their patient population. Tailored measurement and quality improvement resources, coupled with policy mandates to give all patients a voice, would improve the quality of patient-centered care in safety-net organizations. PMID:22415288

  20. A strategy of enhancing the photoactivity of TiO2 containing nonmetal and transition metal dopants

    NASA Astrophysics Data System (ADS)

    Li, Wei; Wei, Shi-Hao; Duan, Xiang-Mei

    2014-02-01

    An effective structural codoping approach is proposed to modify the photoelectrochemical (PEC) properties of anatase TiO2 by being doped with nonmetal (N or/and C) and transition metal (Re) elements. The electronic structures and formation energies of different doped systems are investigated using spin-polarized density functional theory. We find that (C, Re) doped TiO2, with a low formation energy and a large binding energy, reduces the band gap to a large extent, thus it could contribute to the significant enhancement of the photocatalytic activity in the visible-light region. It should be pointed out that, to be successful, the proper proportion of the dopants C and Re should be controlled, so that reasonable PEC properties can be achieved.

  1. Low Molecular Weight Chitosan–Insulin Polyelectrolyte Complex: Characterization and Stability Studies

    PubMed Central

    Al-Kurdi, Zakieh I.; Chowdhry, Babur Z.; Leharne, Stephen A.; Al Omari, Mahmoud M. H.; Badwan, Adnan A.

    2015-01-01

    The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs) on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC) consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC) in a reverse micelle (RM) system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity. PMID:25830681

  2. In situ neutron scattering study of nanostructured PbTe-PbS bulk thermoelectric material

    SciTech Connect

    Ren, Fei; Schmidt, Robert D; Case, Eldon D; An, Ke

    2016-01-01

    Nanostructures play an important role in thermoelectric materials. Their thermal stability, such as phase change and evolution at elevated temperatures, is thus of great interest to the thermoelectric community. In this study, in situ neutron diffraction was used to examine the phase evolution of nanostructured bulk PbTe-PbS materials fabricated using hot pressing and pulsed electrical current sintering (PECS). The PbS second phase was observed in all samples in the as-pressed condition. The temperature dependent lattice parameter and phase composition data show an initial formation of PbS precipitates followed by a redissolution during heating. The redissolution process started around 570 600 K, and completed at approximately 780 K. During cooling, the PECS sample followed a reversible curve while the heating/cooling behavior of the hot pressed sample was irreversible.

  3. Defect characterisation based on heat diffusion using induction thermography testing.

    PubMed

    He, Yunze; Pan, Mengchun; Luo, Feilu

    2012-10-01

    Pulsed eddy current (PEC) thermography (a.k.a. induction thermography) has been successfully applied to detect defects (corrosion, cracks, impact, and delamination) in metal alloy and carbon fiber reinforced plastic. During these applications, the defect detection mechanism is mainly investigated based on the eddy current interaction with defect. In this paper, defect characterisation for wall thinning defect and inner defect in steel is investigated based on heat diffusion. The paper presents the PEC thermography testing, which integrates the reflection mode and transmission mode by means of configuring two cameras on both sides of sample. The defect characterisation methods under transmission mode and reflection mode are investigated and compared through 1D analytical analysis, 3D numerical studies, and experimental studies. The suitable detection mode for wall thinning and inner defects quantification is concluded.

  4. Defect characterisation based on heat diffusion using induction thermography testing

    NASA Astrophysics Data System (ADS)

    He, Yunze; Pan, Mengchun; Luo, Feilu

    2012-10-01

    Pulsed eddy current (PEC) thermography (a.k.a. induction thermography) has been successfully applied to detect defects (corrosion, cracks, impact, and delamination) in metal alloy and carbon fiber reinforced plastic. During these applications, the defect detection mechanism is mainly investigated based on the eddy current interaction with defect. In this paper, defect characterisation for wall thinning defect and inner defect in steel is investigated based on heat diffusion. The paper presents the PEC thermography testing, which integrates the reflection mode and transmission mode by means of configuring two cameras on both sides of sample. The defect characterisation methods under transmission mode and reflection mode are investigated and compared through 1D analytical analysis, 3D numerical studies, and experimental studies. The suitable detection mode for wall thinning and inner defects quantification is concluded.

  5. Tunable photoelectrochemical performance of Au/BiFeO3 heterostructure.

    PubMed

    Huang, Yen-Lin; Chang, Wei Sea; Van, Chien Nguyen; Liu, Heng-Jui; Tsai, Kai-An; Chen, Jhih-Wei; Kuo, Ho-Hung; Tzeng, Wen-Yen; Chen, Yi-Chun; Wu, Chung-Lin; Luo, Chih-Wei; Hsu, Yung-Jung; Chu, Ying-Hao

    2016-08-25

    Ferroelectric photoelectrodes, other than conventional semiconductors, are alternative photo-absorbers in the process of water splitting. However, the capture of photons and efficient transfer of photo-excited carriers remain as two critical issues in ferroelectric photoelectrodes. In this work, we overcome the aforementioned issues by decorating the ferroelectric BiFeO3 (BFO) surface with Au nanocrystals, and thus improving the photoelectrochemical (PEC) performance of BFO film. We demonstrate that the internal field induced by the spontaneous polarization of BFO can (1) tune the efficiency of the photo-excited carriers' separation and charge transfer characteristics in bare BFO photoelectrodes, and (2) modulate an extra optical absorption within the visible light region, created by the surface plasmon resonance excitation of Au nanocrystals to capture more photons in the Au/BFO heterostructure. This study provides key insights for understanding the tunable features of PEC performance, composed of the heterostructure of noble metals and ferroelectric materials. PMID:27533610

  6. Nanostructured tungsten trioxide thin films synthesized for photoelectrocatalytic water oxidation: a review.

    PubMed

    Zhu, Tao; Chong, Meng Nan; Chan, Eng Seng

    2014-11-01

    The recent developments of nanostructured WO3 thin films synthesized through the electrochemical route of electrochemical anodization and cathodic electrodeposition for the application in photoelectrochemical (PEC) water splitting are reviewed. The key fundamental reaction mechanisms of electrochemical anodization and cathodic electrodeposition methods for synthesizing nanostructured WO3 thin films are explained. In addition, the effects of metal oxide precursors, electrode substrates, applied potentials and current densities, and annealing temperatures on size, composition, and thickness of the electrochemically synthesized nanostructured WO3 thin films are elucidated in detail. Finally, a summary is given for the general evaluation practices used to calculate the energy conversion efficiency of nanostructured WO3 thin films and a recommendation is provided to standardize the presentation of research results in the field to allow for easy comparison of reported PEC efficiencies in the near future. PMID:25274424

  7. Biopolymer-Activated Graphitic Carbon Nitride towards a Sustainable Photocathode Material

    PubMed Central

    Zhang, Yuanjian; Schnepp, Zoë; Cao, Junyu; Ouyang, Shuxin; Li, Ying; Ye, Jinhua; Liu, Songqin

    2013-01-01

    Photoelectrochemical (PEC) conversion of solar light into chemical fuels is one of the most promising solutions to the challenge of sustainable energy. Graphitic carbon (IV) nitride polymer (g-CN) is an interesting sustainable photocathode material due to low-cost, visible-light sensitivity, and chemical stability up to 500°C in air. However, grain boundary effects and limited active sites greatly hamper g-CN activity. Here, we demonstrate biopolymer-activation of g-CN through simultaneous soft-templating of a sponge-like structure and incorporation of active carbon-dopant sites. This facile approach results in an almost 300% increase in the cathodic PEC activity of g-CN under simulated solar-irradiation. PMID:23831846

  8. Nanocolloids of indomethacin prepared using sonication and subsequent encapsulation with polysaccharide films.

    PubMed

    Milkova, Viktoria; Kamburova, Kamelia; Radeva, Tsetska

    2013-08-01

    A new procedure was applied for preparation of indomethacin (IMC) nano-particles (ca. 200nm), which includes ultrasonication of micron range IMC crystals in water, followed by short centrifugation to remove the larger drug particles. In order to stabilize the suspension against aggregation and to reduce the release time of the drug, water insoluble IMC particles were coated with chitosan/pectin (CHI/PEC) multilayer film at pH 4. Charge balance in the multilayer film and increase in the film thickness with the number of adsorbed layers was studied by means of electro-optics. The release time of IMC molecules from the encapsulated particles was measured at physiological pH 7, when the solubility of IMC in water increases several times. Addition of small amount of CaCl2 after deposition of PEC layers was applied to compact the multilayer films on the IMC particles.

  9. Atomic layer deposition of metastable β-Fe₂O₃ via isomorphic epitaxy for photoassisted water oxidation.

    PubMed

    Emery, Jonathan D; Schlepütz, Christian M; Guo, Peijun; Riha, Shannon C; Chang, Robert P H; Martinson, Alex B F

    2014-12-24

    We report the growth and photoelectrochemical (PEC) characterization of the uncommon bibyite phase of iron(III) oxide (β-Fe2O3) epitaxially stabilized via atomic layer deposition on an conductive, transparent, and isomorphic template (Sn-doped In2O3). As a photoanode, unoptimized β-Fe2O3 ultrathin films perform similarly to their ubiquitous α-phase (hematite) counterpart, but reveal a more ideal bandgap (1.8 eV), a ∼0.1 V improved photocurrent onset potential, and longer wavelength (>600 nm) spectral response. Stable operation under basic water oxidation justifies further exploration of this atypical phase and motivates the investigation of other unexplored metastable phases as new PEC materials.

  10. Adjusting the Crystallinity of Mesoporous Spinel CoGa2O4 for Efficient Water Oxidation.

    PubMed

    Xu, Zhe; Yan, Shi-Cheng; Shi, Zhan; Yao, Ying-Fang; Zhou, Peng; Wang, Hao-Yu; Zou, Zhi-Gang

    2016-05-25

    Effective and stable electrocatalysts (ECs) are of great importance for the modification of semiconductor (SC) photoanodes, to achieve efficient photoelectrochemical (PEC) water splitting. Herein we demonstrate that the low-crystallinity mesoporous spinel CoGa2O4 oxygen evolution catalyst (OEC), exhibiting excellent bulk electrocatalytic stability and activity for oxygen-evolving reaction (OER), obviously improved water oxidization on a-Fe2O3 photoanode. Low crystallinity not only balances the stability and activity for ECs themselves but facilitates formation of adjustable Schottky junctions between ECs and SCs. Those would contribute to surface state passivation and photogenerated hole extraction, leading to lower onset potential and larger photocurrent. Thus, our finding suggests that low crystallinity could serve as a beneficial feature of ECs to achieve efficient PEC water splitting, owing to its preponderant tendency for the improvement of interface reaction kinetics. PMID:27142693

  11. Demonstration of electronic design automation flow for massively parallel e-beam lithography

    NASA Astrophysics Data System (ADS)

    Brandt, Pieter; Belledent, Jérôme; Tranquillin, Céline; Figueiro, Thiago; Meunier, Stéfanie; Bayle, Sébastien; Fay, Aurélien; Milléquant, Matthieu; Icard, Beatrice; Wieland, Marco

    2014-07-01

    For proximity effect correction in 5 keV e-beam lithography, three elementary building blocks exist: dose modulation, geometry (size) modulation, and background dose addition. Combinations of these three methods are quantitatively compared in terms of throughput impact and process window (PW). In addition, overexposure in combination with negative bias results in PW enhancement at the cost of throughput. In proximity effect correction by over exposure (PEC-OE), the entire layout is set to fixed dose and geometry sizes are adjusted. In PEC-dose to size (DTS) both dose and geometry sizes are locally optimized. In PEC-background (BG), a background is added to correct the long-range part of the point spread function. In single e-beam tools (Gaussian or Shaped-beam), throughput heavily depends on the number of shots. In raster scan tools such as MAPPER Lithography's FLX 1200 (MATRIX platform) this is not the case and instead of pattern density, the maximum local dose on the wafer is limiting throughput. The smallest considered half-pitch is 28 nm, which may be considered the 14-nm node for Metal-1 and the 10-nm node for the Via-1 layer, achieved in a single exposure with e-beam lithography. For typical 28-nm-hp Metal-1 layouts, it was shown that dose latitudes (size of process window) of around 10% are realizable with available PEC methods. For 28-nm-hp Via-1 layouts this is even higher at 14% and up. When the layouts do not reach the highest densities (up to 10∶1 in this study), PEC-BG and PEC-OE provide the capability to trade throughput for dose latitude. At the highest densities, PEC-DTS is required for proximity correction, as this method adjusts both geometry edges and doses and will reduce the dose at the densest areas. For 28-nm-hp lines critical dimension (CD), hole&dot (CD) and line ends (edge placement error), the data path errors are typically 0.9, 1.0 and 0.7 nm (3σ) and below, respectively. There is not a clear data path performance difference between

  12. Theoretical Studies of Dissociative Recombination of Electrons with SH+ Ions

    NASA Astrophysics Data System (ADS)

    Kashinski, D. O.; di Nallo, O. E.; Hickman, A. P.; Mezei, J. Zs.; Colboc, F.; Schneider, I. F.; Chakrabarti, K.; Talbi, D.

    2016-05-01

    We are investigating the dissociative recombination (DR) of electrons with the molecular ion SH+, i.e. e- +SH+ --> S + H . SH+ is found in the interstellar medium (ISM), and little is known concerning its chemistry. Understanding the role of DR of electrons with SH+ will lead to more accurate astrophysical models. Large active-space multi-reference configuration interaction (MRCI) electronic structure calculations were performed using the GAMESS code to obtain ground and excited 2 Π state potential energy curves (PECs) for several values of SH separation. Core-excited Rydberg states have proven to be of huge importance. The block diagonalization method was used to disentangle interacting states and form a diabatic representation of the PECs. Currently we are performing dynamics calculations using Multichannel Quantum Defect Theory (MQDT) to obtain DR rates. The status of the work will be presented at the conference. work supported by the French CNRS, the NSF, the XSEDE, and USMA.

  13. Influence of Gas Flow Rate for Formation of Aligned Nanorods in ZnO Thin Films for Solar-Driven Hydrogen Production

    SciTech Connect

    Shet, S.; Chen, L.; Tang, H.; Nuggehalli, R.; Wang, H.; Yan, Y.; Turner, J.; Al-Jassim, M.

    2012-04-01

    ZnO thin films have been deposited in mixed Ar/N{sub 2} gas ambient at substrate temperature of 500 C by radiofrequency sputtering of ZnO targets. We find that an optimum N{sub 2}-to-Ar ratio in the deposition ambient promotes the formation of well-aligned nanorods. ZnO thin films grown in ambient with 25% N{sub 2} gas flow rate promoted nanorods aligned along c-axis and exhibit significantly enhanced photoelectrochemical (PEC) response, compared with ZnO thin films grown in an ambient with different N{sub 2}-to-Ar gas flow ratios. Our results suggest that chamber ambient is critical for the formation of aligned nanostructures, which offer potential advantages for improving the efficiency of PEC water splitting for H{sub 2} production.

  14. Terahertz epsilon-near-zero graded-index lens.

    PubMed

    Torres, Víctor; Pacheco-Peña, Víctor; Rodríguez-Ulibarri, Pablo; Navarro-Cía, Miguel; Beruete, Miguel; Sorolla, Mario; Engheta, Nader

    2013-04-01

    An epsilon-near-zero graded-index converging lens with planar faces is proposed and analyzed. Each perfectly-electric conducting (PEC) waveguide comprising the lens operates slightly above its cut-off frequency and has the same length but different cross-sectional dimensions. This allows controlling individually the propagation constant and the normalized characteristic impedance of each waveguide for the desired phase front at the lens output while Fresnel reflection losses are minimized. A complete theoretical analysis based on the waveguide theory and Fermat's principle is provided. This is complemented with numerical simulation results of two-dimensional and three-dimensional lenses, made of PEC and aluminum, respectively, and working in the terahertz regime, which show good agreement with the analytical work. PMID:23572004

  15. Photoelectrochemical CO2 reduction on 3C-SiC photoanode in aqueous solution

    NASA Astrophysics Data System (ADS)

    Song, Jun Tae; Iwasaki, Takayuki; Hatano, Mutsuko

    2015-04-01

    Photoelectrochemical (PEC) carbon dioxide (CO2) reduction on a 3C-SiC photoanode is demonstrated in aqueous solution with Pt and Ag counter electrodes. It is demonstrated that 3C-SiC has sufficient potential for CO2 reduction by confirming the band-edge structure. Then, the CO2 reduction is realized by connecting the 3C-SiC photoanode with the counter electrode. As the products of the PEC reaction with an applied bias of 1 V (vs counter electrode) to the 3C-SiC photoanode, hydrogen (H2) and carbon monoxide (CO) were analyzed by highly sensitive micro-gas chromatography, by which the time dependence of the gas products can be analyzed. Under light illumination of the 3C-SiC photoanode, CO2 reduction occurred while producing 2.5 and 9 nmol of CO gas with the Pt and Ag counter electrodes, respectively, after the reaction for 3000 s.

  16. Perceived energy compensation following various sports: an age and sex comparison. Preliminary observations.

    PubMed

    Varley-Campbell, J L; Moore, M S; Ewen, R E; Williams, C A

    2015-12-01

    Following periods of physical activity, it is not uncommon for exercisers to increase their energy intake as a reward deemed 'earned'. Consumers' awareness of the energy within food and expended from exercise has previously been found to be limited. Therefore, the aim was to investigate whether habitual exercisers (50 adults and 49 children from 5 sports clubs) were able to conceptualise the energy expenditure (EE), following 1 h of their regular sports training, into a quantifiable amount of perceived energy compensation (PEC) in the form of food (chocolate) or drink (sports drink). Mean percentage accuracy for the PEC against EE matched <30% (± 29%), a significant underestimation irrespective of sex or sport. Percentage accuracy failed to significantly correlate to age. These findings indicate a necessity to improve nutrition education surrounding the energy costs of exercise relative to the energy contained within foods/drinks for both adults and children.

  17. In Situ Neutron Scattering Study of Nanostructured PbTe-PbS Bulk Thermoelectric Material

    NASA Astrophysics Data System (ADS)

    Ren, Fei; Schmidt, Robert; Case, Eldon D.; An, Ke

    2016-07-01

    Nanostructures play an important role in thermoelectric materials. Their thermal stability, such as phase change and evolution at elevated temperatures, is thus of great interest to the thermoelectric community. In this study, in situ neutron diffraction was used to examine the phase evolution of nanostructured bulk PbTe-PbS materials fabricated using hot pressing and pulsed electrical current sintering (PECS). The PbS second phase was observed in all samples in the as-pressed condition. The temperature dependent lattice parameter and phase composition data show an initial formation of PbS precipitates followed by a redissolution during heating. The redissolution process started around 570-600 K, and completed at approximately 780 K. During cooling, the PECS sample followed a reversible curve while the heating/cooling behavior of the hot pressed sample was irreversible.

  18. Spatially Separated Photosystem II and a Silicon Photoelectrochemical Cell for Overall Water Splitting: A Natural-Artificial Photosynthetic Hybrid.

    PubMed

    Wang, Wangyin; Wang, Hong; Zhu, Qingjun; Qin, Wei; Han, Guangye; Shen, Jian-Ren; Zong, Xu; Li, Can

    2016-08-01

    Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H2 and O2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems. PMID:27345863

  19. Perceived energy compensation following various sports: an age and sex comparison. Preliminary observations.

    PubMed

    Varley-Campbell, J L; Moore, M S; Ewen, R E; Williams, C A

    2015-12-01

    Following periods of physical activity, it is not uncommon for exercisers to increase their energy intake as a reward deemed 'earned'. Consumers' awareness of the energy within food and expended from exercise has previously been found to be limited. Therefore, the aim was to investigate whether habitual exercisers (50 adults and 49 children from 5 sports clubs) were able to conceptualise the energy expenditure (EE), following 1 h of their regular sports training, into a quantifiable amount of perceived energy compensation (PEC) in the form of food (chocolate) or drink (sports drink). Mean percentage accuracy for the PEC against EE matched <30% (± 29%), a significant underestimation irrespective of sex or sport. Percentage accuracy failed to significantly correlate to age. These findings indicate a necessity to improve nutrition education surrounding the energy costs of exercise relative to the energy contained within foods/drinks for both adults and children. PMID:26130299

  20. Molecular screening of virulence genes in extraintestinal pathogenic Escherichia coli isolated from human blood culture in Brazil.

    PubMed

    Koga, Vanessa L; Tomazetto, Geizecler; Cyoia, Paula S; Neves, Meiriele S; Vidotto, Marilda C; Nakazato, Gerson; Kobayashi, Renata K T

    2014-01-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the main etiological agents of bloodstream infections caused by Gram-negative bacilli. In the present study, 20 E. coli isolates from human hemocultures were characterized to identify genetic features associated with virulence (pathogenicity islands markers, phylogenetic group, virulence genes, plasmid profiles, and conjugative plasmids) and these results were compared with commensal isolates. The most prevalent pathogenicity island, in strains from hemoculture, were PAI IV536, described by many researchers as a stable island in enterobacteria. Among virulence genes, iutA gene was found more frequently and this gene enconding the aerobactin siderophore receptor. According to the phylogenetic classification, group B2 was the most commonly found. Additionally, through plasmid analysis, 14 isolates showed plasmids and 3 of these were shown to be conjugative. Although in stool samples of healthy people the presence of commensal strains is common, human intestinal tract may serve as a reservoir for ExPEC.

  1. Simultaneous estimation of plasma parameters from spectroscopic data of neutral helium using least square fitting of CR-model

    NASA Astrophysics Data System (ADS)

    Jain, Jalaj; Prakash, Ram; Vyas, Gheesa Lal; Pal, Udit Narayan; Chowdhuri, Malay Bikas; Manchanda, Ranjana; Halder, Nilanjan; Choyal, Yaduvendra

    2015-12-01

    In the present work an effort has been made to estimate the plasma parameters simultaneously like—electron density, electron temperature, ground state atom density, ground state ion density and metastable state density from the observed visible spectra of penning plasma discharge (PPD) source using least square fitting. The analysis is performed for the prominently observed neutral helium lines. The atomic data and analysis structure (ADAS) database is used to provide the required collisional-radiative (CR) photon emissivity coefficients (PECs) values under the optical thin plasma condition in the analysis. With this condition the estimated plasma temperature from the PPD is found rather high. It is seen that the inclusion of opacity in the observed spectral lines through PECs and addition of diffusion of neutrals and metastable state species in the CR-model code analysis improves the electron temperature estimation in the simultaneous measurement.

  2. Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Grand Lake O' the Cherokees, Northeast Oklahoma, 1940-2008

    USGS Publications Warehouse

    Juracek, Kyle E.; Becker, Mark F.

    2009-01-01

    profiles reflect the complex interaction of several factors including historical mining and related activities, mine drainage, remediation, landscape stabilization, precipitation and associated runoff, and the erosion and transport of contaminated and clean sediments within the basin. Compared to sediment-quality guidelines, the Grand Lake samples had cadmium concentrations that were substantially less than the general probable-effects concentration (PEC) (4.98 mg/kg) and a TSMD-specific PEC (11.1 mg/kg). The PECs represent the concentration above which toxic biological effects are likely to occur. Likewise, all sediment samples had lead concentrations that were substantially less than the general PEC (128 mg/kg) and a TSMD-specific PEC (150 mg/kg). Zinc concentrations typically exceeded the general PEC (459 mg/kg), but were substantially less than a TSMD-specific PEC (2,083 mg/kg). Throughout the history of Grand Lake, lead and zinc concentrations in the deposited sediment did not approach or exceed the TSMD-specific PECs. As of 2008, legacy effects of mining still included the delivery of contaminated sediment to Grand Lake by the Spring and Neosho Rivers. The Neosho River, with its larger flows and less-contaminated sediment, likely dilutes the load of contaminated sediment delivered to Grand Lake by the Spring River. The information contained in this report provides a baseline of Grand Lake conditions with which to compare future conditions that may represent a response to changes in mining-related activity in the Grand Lake Basin.

  3. Hydrogen Storage and Production Project

    SciTech Connect

    Bhattacharyya, Abhijit; Biris, A. S.; Mazumder, M. K.; Karabacak, T.; Kannarpady, Ganesh; Sharma, R.

    2011-07-31

    This is the final technical report. This report is a summary of the project. The goal of our project is to improve solar-to-hydrogen generation efficiency of the PhotoElectroChemical (PEC) conversion process by developing photoanodes with high absorption efficiency in the visible region of the solar radiation spectrum and to increase photo-corrosion resistance of the electrode for generating hydrogen from water. To meet this goal, we synthesized nanostructured heterogeneous semiconducting photoanodes with a higher light absorption efficiency compared to that of TiO2 and used a corrosion protective layer of TiO2. While the advantages of photoelectrochemical (PEC) production of hydrogen have not yet been realized, the recent developments show emergence of new nanostructural designs of photoanodes and choices of materials with significant gains in photoconversion efficiency.

  4. Overall Photoelectrochemical Water Splitting using Tandem Cell under Simulated Sunlight.

    PubMed

    Kim, Jin Hyun; Kaneko, Hiroyuki; Minegishi, Tsutomu; Kubota, Jun; Domen, Kazunari; Lee, Jae Sung

    2016-01-01

    A stand-alone photoelectrochemical (PEC) water-splitting system driven only by sunlight was demonstrated with a tandem-scheme of Pt/CdS/CuGa3 Se5 /(Ag,Cu)GaSe2 photocathode and NiOOH/FeOOH/Mo:BiVO4 photoanode in a neutral phosphate buffer solution as an electrolyte. The as-prepared semi-transparent Mo:BiVO4 layer allows sunlight to pass through the top photoanode and reach the bottom photocathode. Consequently, the tandem cell showed stoichiometric hydrogen and oxygen evolution with a solar-to-hydrogen (STH) conversion efficiency of 0.67 % over 2 h without degradation. The stability and STH efficiency are the highest among similar configuration of PEC tandem cells.

  5. Aquatic risk assessment of 2-sulfonato fatty acid methyl ester sodium salt (MES).

    PubMed

    Miura, Kazuaki

    2007-01-01

    The aquatic risk of 2-sulfonato fatty acid methyl ester sodium salt (MES) used in household detergents was assessed. The environmental exposure assessment expressed as predicted environmental concentration (PEC) was determined on the basis of monitoring results from the seven sites of four rivers in the urban area in Tokyo and Osaka. The 95 percentile as well as geometric mean of the MES concentration was found to exhibit a good correlation with the geometric mean of the Biochemical Oxygen Demand (BOD; the latter's regression was greater than 0.99). The predicted no effect concentration (PNEC) for the aquatic environment was estimated by performing chronic assays of algae and daphnia. The risk characterization ratio (RCR: PEC/PNEC) was less than 1. Therefore, it is concluded that MES will not adversely affect the aquatic environment in Japan.

  6. Photoelectrochemical characterization of hydrogenated TiO2 nanotubes as photoanodes for sensing applications.

    PubMed

    Li, Sheng; Qiu, Jingxia; Ling, Min; Peng, Feng; Wood, Barry; Zhang, Shanqing

    2013-11-13

    In this work, hydrogenated TiO2 nanotubes (H-TNTs) electrodes were successfully fabricated via the anodization of a titanium sheet followed by a hydrogenation process. Oxygen vacancies were induced in the crystalline structure of TiO2 nanotubes (TNTs) as shallow donors that enhance the electronic conductivity of the TNTs. This improvement in the electronic conductivity and photoelectrocatalytic (PEC) performance was confirmed and evaluated by a photoelectrochemical characterization. Most importantly, the H-TNTs electrode was able to degrade potassium hydrogen phthalate (strong adsorbent) and glucose (weak adsorbent) indiscriminately. The corresponding photocurrents at the H-TNTs were 2-fold greater than that of the TNTs samples for the same concentrations of the organic compounds. This suggests that the H-TNTs electrode can be a promising sensor for the PEC determination of individual organic compounds or as an aggregative parameter of organic compounds (e.g., chemical oxygen demand). PMID:24083843

  7. Synthesis and characterization of chitosan-based polyelectrolyte complexes, doped by quantum dots

    NASA Astrophysics Data System (ADS)

    Abuzova, N. V.; Gerasimova, M. A.; Slabko, V. V.; Slyusareva, E. A.

    2015-12-01

    Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.

  8. Gold nanocluster-sensitized TiO2 nanotubes to enhance the photocatalytic hydrogen generation under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Hongkai; Chen, Fuyi; Li, Weiyin; Tian, Tian

    2015-08-01

    The wide band-gap of TiO2 semiconductors hinders the photocatalytic hydrogen generation under visible light. In this research, we introduce glutathione-protected gold (Au-GSH) nanoclusters as a sensitizer to extend the active region of TiO2 up to a wavelength of 510 nm under visible light spectrum. We demonstrate that Au-GSH nanoclusters are capable of enhancing photocatalytic effects for hydrogen generation in photo-electrochemical cells (PECs). The combined effects of metal nanoclusters and sacrificial agent (EDTA) enhance the photocurrent up to six times more than what can be achieved using Au-GSH nanoclusters without EDTA. Moreover, the mechanisms of interaction between Au-GSH nanoclusters and EDTA have been investigated through instantaneous photoresponse measurements. A single electrode system has been designed to simplify PECs for hydrogen generation, which exhibits the same enhanced photocatalytic effect.

  9. Polyelectrolyte Complex for Heparin Binding Domain Osteogenic Growth Factor Delivery.

    PubMed

    Wing Moon Lam, Raymond; Abbah, Sunny Akogwu; Ming, Wang; Naidu, Mathanapriya; Ng, Felly; Tao, Hu; Goh Cho Hong, James; Ting, Kang; Hee Kit, Wong

    2016-01-01

    During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone fusion. Large doses of highly potent biological agents are required due to growth factor instability as a result of rapid enzymatic degradation as well as carrier inefficiencies in localizing sufficient amounts of growth factor at implant sites. Hence, strategies that prolong the stability of growth factors such as BMP-2/NELL-1, and control their release could actually lower their efficacious dose and thus reduce the need for larger doses during future bone regeneration surgeries. This in turn will reduce side effects and growth factor costs. Self-assembled PECs have been fabricated to provide better control of BMP-2/NELL-1 delivery via heparin binding and further potentiate growth factor bioactivity by enhancing in vivo stability. Here we illustrate the simplicity of PEC fabrication which aids in the delivery of a variety of growth factors during reconstructive bone surgeries. PMID:27585207

  10. Seniority Number in Valence Bond Theory.

    PubMed

    Chen, Zhenhua; Zhou, Chen; Wu, Wei

    2015-09-01

    In this work, a hierarchy of valence bond (VB) methods based on the concept of seniority number, defined as the number of singly occupied orbitals in a determinant or an orbital configuration, is proposed and applied to the studies of the potential energy curves (PECs) of H8, N2, and C2 molecules. It is found that the seniority-based VB expansion converges more rapidly toward the full configuration interaction (FCI) or complete active space self-consistent field (CASSCF) limit and produces more accurate PECs with smaller nonparallelity errors than its molecular orbital (MO) theory-based analogue. Test results reveal that the nonorthogonal orbital-based VB theory provides a reverse but more efficient way to truncate the complete active Hilbert space by seniority numbers.

  11. Enhanced photoelectrochemical activity for Cu and Ti doped hematite: The first principles calculations

    SciTech Connect

    Meng, X. Y.; Qin, G. W.; Li, S.; Ren, Y. P.; Pei, W. L.; Zuo, L.; Wen, X. H.

    2011-03-14

    To improve photoelectrochemical (PEC) activity of hematite, the modification of energy band by doping 3d transition metal ions Cu and Ti into {alpha}-Fe{sub 2}O{sub 3} were studied via the first-principles calculations with density function theory (DFT)+U method. The results show that the band gap of hematite is {approx}2.1 eV and n-type dopant Ti improves the electric conductivity, confirmed by recent experiments. The p-type dopant Cu enhances the utilization ratio of solar energy, shifts both valance, and conduction band edges to a higher energy level, satisfying hydrogen production in the visible light driven PEC water splitting without voltage bias.

  12. Dye-sensitized PS-b-P2VP-templated nickel oxide films for photoelectrochemical applications

    PubMed Central

    Massin, Julien; Bräutigam, Maximilian; Kaeffer, Nicolas; Queyriaux, Nicolas; Field, Martin J.; Schacher, Felix H.; Popp, Jürgen; Chavarot-Kerlidou, Murielle; Dietzek, Benjamin; Artero, Vincent

    2015-01-01

    Moving from homogeneous water-splitting photocatalytic systems to photoelectrochemical devices requires the preparation and evaluation of novel p-type transparent conductive photoelectrode substrates. We report here on the sensitization of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymer-templated NiO films with an organic push–pull dye. The potential of these new templated NiO film preparations for photoelectrochemical applications is compared with NiO material templated by F108 triblock copolymers. We conclude that NiO films are promising materials for the construction of dye-sensitized photocathodes to be inserted into photoelectrochemical (PEC) cells. However, a combined effort at the interface between materials science and molecular chemistry, ideally funded within a Global Artificial Photosynthesis Project, is still needed to improve the overall performance of the photoelectrodes and progress towards economically viable PEC devices. PMID:26052420

  13. Proximity effect correction sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Zepka, Alex; Zimmermann, Rainer; Hoppe, Wolfgang; Schulz, Martin

    2010-05-01

    Determining the quality of a proximity effect correction (PEC) is often done via 1-dimensional measurements such as: CD deviations from target, corner rounding, or line-end shortening. An alternative approach would compare the entire perimeter of the exposed shape and its original design. Unfortunately, this is not a viable solution as there is a practical limit to the number of metrology measurements that can be done in a reasonable amount of time. In this paper we make use of simulated results and introduce a method which may be considered complementary to the standard way of PEC qualification. It compares simulated contours with the target layout via a Boolean XOR operation with the area of the XOR differences providing a direct measure of how close a corrected layout approximates the target.

  14. Titanium and Magnesium Co-Alloyed Hematite Thin Films for Photoelectrochemical Water Splitting

    SciTech Connect

    Tang, H.; Yin, W. J.; Matin, M. A.; Wang, H.; Deutsch, T.; Al-Jassim, M. M.; Turner, J. A.; Yan, Y.

    2012-04-01

    Using a combination of density functional theory calculation and materials synthesis and characterization we examine the properties of charge-compensated Ti and Mg co-alloyed hematite thin films for the application of photoelectrochemical (PEC) water splitting. We find that the charge-compensated co-alloying results in the following effects: (1) It enhances the solubility of Mg and Ti, which leads to reduced electron effective mass and therefore increased electron mobility; (2) It tunes the carrier density and therefore allows the optimization of electrical conductivity; and (3) It reduces the density of charged defects and therefore reduces carrier recombination. As a result, the Ti and Mg co-alloyed hematite thin films exhibit improved water oxidation photocurrent magnitudes as compared to pure hematite thin films. Our results suggest that charge-compensated co-alloying is a plausible approach for engineering hematite for the application of PEC water splitting.

  15. Spatially Separated Photosystem II and a Silicon Photoelectrochemical Cell for Overall Water Splitting: A Natural-Artificial Photosynthetic Hybrid.

    PubMed

    Wang, Wangyin; Wang, Hong; Zhu, Qingjun; Qin, Wei; Han, Guangye; Shen, Jian-Ren; Zong, Xu; Li, Can

    2016-08-01

    Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H2 and O2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems.

  16. Curing BiVO4 Photoanodes with Ultraviolet Light Enhances Photoelectrocatalysis.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-01-26

    Exposure of BiVO4 photoanodes to ultraviolet (UV) radiation for extended time periods (e.g., 20 h) produces a morphological change and concomitant improvement in photo-electrocatalytic (PEC) efficiency for driving water splitting directly by sunlight. The ∼230 mV cathodic shift in onset potential and doubling of the photocurrent at 1.23 V vs. RHE after UV curing are comparable to the effects engendered by the presence of a secondary catalyst layer. PEC measurements and absorption spectra indicate that the cathodic shift after UV curing corresponds to a suppression of charge recombination and a greater photovoltage generation caused by the shift of the flat-band potential, and not an improvement in electrocatalytic activity or light absorption. Spectroscopic surface analysis suggests that surface defect sites, which are eliminated by UV curing, for the differences in observed charge recombination. PMID:26689617

  17. Nanostructured tungsten trioxide thin films synthesized for photoelectrocatalytic water oxidation: a review.

    PubMed

    Zhu, Tao; Chong, Meng Nan; Chan, Eng Seng

    2014-11-01

    The recent developments of nanostructured WO3 thin films synthesized through the electrochemical route of electrochemical anodization and cathodic electrodeposition for the application in photoelectrochemical (PEC) water splitting are reviewed. The key fundamental reaction mechanisms of electrochemical anodization and cathodic electrodeposition methods for synthesizing nanostructured WO3 thin films are explained. In addition, the effects of metal oxide precursors, electrode substrates, applied potentials and current densities, and annealing temperatures on size, composition, and thickness of the electrochemically synthesized nanostructured WO3 thin films are elucidated in detail. Finally, a summary is given for the general evaluation practices used to calculate the energy conversion efficiency of nanostructured WO3 thin films and a recommendation is provided to standardize the presentation of research results in the field to allow for easy comparison of reported PEC efficiencies in the near future.

  18. Immobilization of a Molecular Ruthenium Catalyst on Hematite Nanorod Arrays for Water Oxidation with Stable Photocurrent.

    PubMed

    Fan, Ke; Li, Fusheng; Wang, Lei; Daniel, Quentin; Chen, Hong; Gabrielsson, Erik; Sun, Junliang; Sun, Licheng

    2015-10-12

    Photoelectrochemical (PEC) cells for light-driven water splitting are prepared using hematite nanorod arrays on conductive glass as the photoanode. These devices improve the photocurrent of the hematite-based photoanode for water splitting, owing to fewer surface traps and decreased electron recombination resulting from the one-dimensional structure. By employing a molecular ruthenium co-catalyst, which contains a strong 2,6-pyridine-dicarboxylic acid anchoring group at the hematite photoanode, the photocurrent of the PEC cell is enhanced with high stability for over 10 000 s in a 1 m KOH solution. This approach can pave a route for combining one-dimensional nanomaterials and molecular catalysts to split water with high efficiency and stability. PMID:26315677

  19. Investigations on the activity of poly(2-oxazoline) enzyme conjugates dissolved in organic solvents.

    PubMed

    Konieczny, Stefan; Krumm, Christian; Doert, Dominik; Neufeld, Katharina; Tiller, Joerg C

    2014-07-10

    The use of enzymes in organic solvents offers a great opportunity for the highly selective synthesis of complex organic compounds. In this study we investigate the POXylation of several enzymes with different polyoxazolines ranging from the hydrophilic poly(2-methyl-oxazoline) (PMOx) to the hydrophobic poly(2-heptyl-oxazoline) (PHeptOx). As reported previously on the examples of model enzymes POXylation mediated by pyromellitic acid dianhydride results in highly modified, organosoluble protein conjugates. This procedure is here extended to a larger number of proteins and optimized for the different polyoxazolines. The resulting polymer-enzyme conjugates (PEC) became soluble in different organic solvents ranging from hydrophilic DMF to even toluene. These conjugates were characterized regarding their solubility and especially their activity in organic solvents and in some cases the PECs showed significantly (up to 153,000 fold) higher activities than the respective native enzymes. PMID:24709400

  20. Empirical in operando analysis of the charge carrier dynamics in hematite photoanodes by PEIS, IMPS and IMVS.

    PubMed

    Klotz, Dino; Ellis, David Shai; Dotan, Hen; Rothschild, Avner

    2016-09-14

    In this Perspective, we introduce intensity modulated photocurrent/voltage spectroscopy (IMPS and IMVS) as powerful tools for the analysis of charge carrier dynamics in photoelectrochemical (PEC) cells for solar water splitting, taking hematite (α-Fe2O3) photoanodes as a case study. We complete the picture by including photoelectrochemical impedance spectroscopy (PEIS) and linking the trio of PEIS, IMPS and IMVS, introduced here as photoelectrochemical immittance triplets (PIT), both mathematically and phenomenologically, demonstrating what conclusions can be extracted from these measurements. A novel way of analyzing the results by an empirical approach with minimal presumptions is introduced, using the distribution of relaxation times (DRT) function. The DRT approach is compared to conventional analysis approaches that are based on physical models and therefore come with model presumptions. This work uses a thin film hematite photoanode as a model system, but the approach can be applied to other PEC systems as well. PMID:27524381

  1. Synthesis and enhanced photoelectrocatalytic activity of p-n junction Co3O4/TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Dai, Gaopeng; Liu, Suqin; Liang, Ying; Luo, Tianxiong

    2013-01-01

    Co3O4/TiO2 nanotube arrays (NTs) were prepared by depositing Co3O4 nanoparticles (NPs) on the tube wall of the self-organized TiO2 NTs using an impregnating-deposition-decompostion method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. The photoelectrocatalytic (PEC) activity is evaluated by degradation of methyl orange (MO) aqueous solution. The prepared Co3O4/TiO2 NTs exhibit much higher PEC activity than TiO2 NTs due to the p-n junction formed between Co3O4 and TiO2.

  2. Adjusting the Crystallinity of Mesoporous Spinel CoGa2O4 for Efficient Water Oxidation.

    PubMed

    Xu, Zhe; Yan, Shi-Cheng; Shi, Zhan; Yao, Ying-Fang; Zhou, Peng; Wang, Hao-Yu; Zou, Zhi-Gang

    2016-05-25

    Effective and stable electrocatalysts (ECs) are of great importance for the modification of semiconductor (SC) photoanodes, to achieve efficient photoelectrochemical (PEC) water splitting. Herein we demonstrate that the low-crystallinity mesoporous spinel CoGa2O4 oxygen evolution catalyst (OEC), exhibiting excellent bulk electrocatalytic stability and activity for oxygen-evolving reaction (OER), obviously improved water oxidization on a-Fe2O3 photoanode. Low crystallinity not only balances the stability and activity for ECs themselves but facilitates formation of adjustable Schottky junctions between ECs and SCs. Those would contribute to surface state passivation and photogenerated hole extraction, leading to lower onset potential and larger photocurrent. Thus, our finding suggests that low crystallinity could serve as a beneficial feature of ECs to achieve efficient PEC water splitting, owing to its preponderant tendency for the improvement of interface reaction kinetics.

  3. The military health services system model for pharmacoeconomic decision making.

    PubMed

    Ries, A J; Potyk, R P; Brier, K L; Miller, M R; Tornow, J J; Weber, M P; Finder, S F; Reeves, C S

    1995-05-01

    Pharmaceutical expenditures have been increasing over the last few decades, both in the private sector and the Department of Defense (DoD). The Pharmacoeconomic Center (PEC), staffed with personnel from the Army, Navy, and Air Force, was established in 1993 to develop the means to control these pharmaceutical expenditures and to develop the DoD TriService Formulary (TSF). The TSF serves as the basis for a consistent and equitable pharmacy benefit for DoD patients. The initial TSF contains medications that are well accepted as standard therapy and are currently available at most military facilities. Revisions to the initial TSF are based on pharmacoeconomic analyses of ambulatory disease states accounting for the majority of pharmaceutical expenditures. The PEC also develops treatment guidelines, preferred drug lists, and drug use evaluation criteria based on the results of each disease state analysis. PMID:10142786

  4. Electrochemically hydrogenated TiO2 nanotubes with improved photoelectrochemical water splitting performance

    PubMed Central

    2013-01-01

    One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as photoanode for photoelectrochemical (PEC) water splitting. In this work, we report a facile and eco-friendly electrochemical hydrogenation method to modify the electronic and PEC properties of ATO nanotube films. The hydrogenated ATO (ATO-H) electrodes present a significantly improved photocurrent of 0.65 mA/cm2 in comparison with that of pristine ATO nanotubes (0.29 mA/cm2) recorded under air mass 1.5 global illumination. The incident photon-to-current efficiency measurement suggests that the enhanced photocurrent of ATO-H nanotubes is mainly ascribed to the improved photoactivity in the UV region. We propose that the electrochemical hydrogenation induced surface oxygen vacancies contribute to the substantially enhanced electrical conductivity and photoactivity. PMID:24047205

  5. Band structure engineering of semiconductors for enhanced photoelectrochemical water splitting: The case of TiO2

    NASA Astrophysics Data System (ADS)

    Yin, Wan-Jian; Tang, Houwen; Wei, Su-Huai; Al-Jassim, Mowafak M.; Turner, John; Yan, Yanfa

    2010-07-01

    Here, we propose general strategies for the rational design of semiconductors to simultaneously meet all of the requirements for a high-efficiency, solar-driven photoelectrochemical (PEC) water-splitting device. As a case study, we apply our strategies for engineering the popular semiconductor, anatase TiO2 . Previous attempts to modify known semiconductors such as TiO2 have often focused on a particular individual criterion such as band gap, neglecting the possible detrimental consequence to other important criteria. Density-functional theory calculations reveal that with appropriate donor-acceptor coincorporation alloys with anatase TiO2 hold great potential to satisfy all of the criteria for a viable PEC device. We predict that (Mo, 2N) and (W, 2N) are the best donor-acceptor combinations in the low-alloy concentration regime whereas (Nb, N) and (Ta, N) are the best choice of donor-acceptor pairs in the high-alloy concentration regime.

  6. QD co-sensitized and nitrogen doped TiO2 nanocomposite for photoelectrochemical hydrogen generation

    NASA Astrophysics Data System (ADS)

    Hensel, Jennifer; Canin, Max; Zhang, Jin Z.

    2010-08-01

    Metal oxides are promising for solar energy conversion applications since they are less expensive and easier to produce than conventional single crystal silicon. In this paper we focused on CdSe and CdS quantum dot (QD) co-sensitized and nitrogen doped TiO2 (N:TiO2) nanocomposite photoanodes for photoelectrochemical (PEC) water splitting for hydrogen generation. PEC, UV-vis and scanning electron microscopy (SEM) characterizations of the nanostructured films were carried out. The QD co-sensitized and N-doped TiO2 photoanodes exhibits increased photocurrent compared to cosensitized TiO2 without N-doping This is tentatively attributed to enhanced hole transport by oxygen vacancy states that are increased upon nitrogen doping. The enhanced hole transport facilitates overall charge transfer and transport and thereby results in improved photocurrent.

  7. Dendritic Au/TiO2 nanorod arrays for visible-light driven photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Su, Fengli; Wang, Tuo; Lv, Rui; Zhang, Jijie; Zhang, Peng; Lu, Jianwei; Gong, Jinlong

    2013-09-01

    This paper describes the synthesis of TiO2 branched nanorod arrays (TiO2 BNRs) with plasmonic Au nanoparticles attached on the surface. Such Au/TiO2 BNR composites exhibit high photocatalytic activity in photoelectrochemical (PEC) water splitting. The unique structure of Au/TiO2 BNRs shows enhanced activity with a photocurrent of 0.125 mA cm-2 under visible light (>=420 nm) and 2.32 +/- 0.1 mA cm-2 under AM 1.5 G illumination (100 mW cm-2). The obtained photocurrent is comparable to the highest value ever reported. Furthermore, the Au/TiO2 BNRs achieve the highest efficiency of ~1.27% at a low bias of 0.50 V vs. RHE, indicating elevated charge separation and transportation efficiencies. The high PEC performance is mainly due to the plasmonic effect of Au nanoparticles, which enhances the visible light absorption, together with the large surface area, efficient charge separation and high carrier mobility of the TiO2 BNRs. The carrier density of Au/TiO2 BNRs is nearly 6 times higher than the pristine TiO2 BNRs as calculated by the Mott-Schottky plot. Based on the analysis by UV-Vis spectroscopy, electrochemical impedance spectroscopy, and photoluminescence, a mechanism was proposed to explain the high activity of Au/TiO2 BNRs in PEC water splitting. The capability of synthesizing highly visible light active Au/TiO2 BNR based photocatalysts is useful for solar conversion applications, such as PEC water splitting, dye-sensitized solar cells and photovoltaic devices.This paper describes the synthesis of TiO2 branched nanorod arrays (TiO2 BNRs) with plasmonic Au nanoparticles attached on the surface. Such Au/TiO2 BNR composites exhibit high photocatalytic activity in photoelectrochemical (PEC) water splitting. The unique structure of Au/TiO2 BNRs shows enhanced activity with a photocurrent of 0.125 mA cm-2 under visible light (>=420 nm) and 2.32 +/- 0.1 mA cm-2 under AM 1.5 G illumination (100 mW cm-2). The obtained photocurrent is comparable to the highest value ever

  8. Dye-Sensitized and Localized Surface Plasmon Resonance Enhanced Visible-Light Photoelectrochemical Biosensors for Highly Sensitive Analysis of Protein Kinase Activity.

    PubMed

    Yan, Zhiyong; Wang, Zonghua; Miao, Zhuang; Liu, Yang

    2016-01-01

    A novel visible-light photoelectrochemical (PEC) biosensor based on localized surface plasmon resonance (LSPR) enhancement and dye sensitization was fabricated for highly sensitive analysis of protein kinase activity with ultralow background. In this strategy, DNA conjugated gold nanoparticles (DNA@AuNPs) were assembled on the phosphorylated kemptide modified TiO2/ITO electrode through the chelation between Zr(4+) ions and phosphate groups, then followed by the intercalation of [Ru(bpy)3](2+) into DNA grooves. The adsorbed [Ru(bpy)3](2+) can harvest visible light to produce excited electrons that inject into the TiO2 conduction band to form photocurrent under visible light irradiation. In addition, the photocurrent efficiency was further improved by the LSPR of AuNPs under the irradiation of visible light. Moreover, because of the excellent conductivity and large surface area of AuNPs that facilitate electron-transfer and accommodate large number of [Ru(bpy)3](2+), the photocurrent was significantly amplified, affording an extremely sensitive PEC analysis of kinase activity with ultralow background signals. The detection limit of as-proposed PEC biosensor was 0.005 U mL(-1) (S/N = 3). The biosensor also showed excellent performances for quantitative kinase inhibitor screening and PKA activities detection in MCF-7 cell lysates under forskolin and ellagic acid stimulation. The developed dye-sensitization and LSPR enhancement visible-light PEC biosensor shows great potential in protein kinases-related clinical diagnosis and drug discovery. PMID:26648204

  9. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    NASA Astrophysics Data System (ADS)

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-08-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as ‑0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at ‑0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under ‑0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination.

  10. Ligand-Binding Pocket Bridges DNA-Binding and Dimerization Domains of the Urate-Responsive MarR Homologue MftR from Burkholderia thailandensis

    PubMed Central

    2015-01-01

    Members of the multiple antibiotic resistance regulator (MarR) family often regulate gene activity by responding to a specific ligand. In the absence of ligand, most MarR proteins function as repressors, while ligand binding causes attenuated DNA binding and therefore increased gene expression. Previously, we have shown that urate is a ligand for MftR (major facilitator transport regulator), which is encoded by the soil bacterium Burkholderia thailandensis. We show here that both mftR and the divergently oriented gene mftP encoding a major facilitator transport protein are upregulated in the presence of urate. MftR binds two cognate sites in the mftR-mftP intergenic region with equivalent affinity and sensitivity to urate. Mutagenesis of four conserved residues previously reported to be involved in urate binding to Deinococcus radiodurans HucR and Rhizobium radiobacter PecS significantly reduced protein stability and DNA binding affinity but not ligand binding. These data suggest that residues equivalent to those implicated in ligand binding to HucR and PecS serve structural roles and that MftR relies on distinct residues for ligand binding. MftR exhibits a two-step melting transition suggesting independent unfolding of the dimerization and DNA-binding regions; urate binding or mutations in the predicted ligand-binding sites result in one-step unfolding transitions. We suggest that MftR binds the ligand in a cleft between the DNA-binding lobes and the dimer interface but that the mechanism of ligand-mediated attenuation of DNA binding differs from that proposed for other urate-responsive MarR homologues. Since DNA binding by MftR is attenuated at 37 °C, our data also suggest that MftR responds to both ligand and a thermal upshift by attenuated DNA binding and upregulation of the genes under its control. PMID:24955985

  11. Nitrogen and cobalt co-doped zinc oxide nanowires - Viable photoanodes for hydrogen generation via photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Hong, Daeho; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2015-12-01

    Photoelectrochemical (PEC) water splitting has been considered as a promising and environmentally benign approach for efficient and economic hydrogen generation by utilization of solar energy. Development of semiconductor materials with low band gap, high photoelectrochemical activity and stability has been of particular interest for a viable PEC water splitting system. In this study, Co doped ZnO, .i.e., (Zn0.95Co0.05)O nanowires (NWs) was selected as the composition for further co-doping with nitrogen by comparing solar to hydrogen efficiency (SHE) of ZnO NWs with that of various compositions of (Zn1-xCox)O NWs (x = 0, 0.05, 0.1). Furthermore, nanostructured vertically aligned Co and N-doped ZnO, .i.e., (Zn1-xCox)O:N NWs (x = 0.05) have been studied as photoanodes for PEC water splitting. An optimal SHE of 1.39% the highest reported so far to the best of our knowledge for ZnO based photoanodes was obtained for the co-doped NWs, (Zn0.95Co0.05)O:N - 600 NWs generated at 600 °C in ammonia atmosphere. Further, (Zn0.95Co0.05)O:N-600 NWs exhibited excellent photoelectrochemical stability under illumination compared to pure ZnO NWs. These promising results suggest the potential of (Zn0.95Co0.05)O:N-600 NWs as a viable photoanode in PEC water splitting cell. Additionally, theoretical first principles study conducted explains the beneficial effects of Co and N co-doping on both, the electronic structure and the band gap of ZnO.

  12. Preactivated thiomers: evaluation of gastroretentive minitablets.

    PubMed

    Hauptstein, Sabine; Müller, Christiane; Dünnhaupt, Sarah; Laffleur, Flavia; Bernkop-Schnürch, Andreas

    2013-11-18

    The object of this study was to evaluate the potential of a recently developed preactivated thiolated pectin derivative as mucoadhesive excipient in drug delivery to the gastric cavity. Pectin (Pec) was chemically modified with L-cysteine (Cys). The free thiol groups of resulting thiomer were activated with 2-mercaptonicotinic acid (MNA) in order to improve stability and reactivity of attached thiol groups over a broad pH range. Multiunit dosage form properties of the resulting conjugate (Pec-Cys-MNA) were compared to unmodified pectin and the intermediate thiolated using rosuvastatin calcium as a model drug in loaded minitablets. Obtained results were compared with unmodified pectin and the intermediate thiolated pectin. Approximately half of attached thiol groups (507 μmol/g polymer) have been preactivated. Minitablets were evaluated regarding mucoadhesive properties, hardness, disintegration behavior, swelling characteristics and release of rosuvastatin calcium. Mediated by covalent bonds between the polymer and cysteine-rich subdomains in mucus, total work of adhesion increased more than 5-fold. The modification had no impact on hardness of compressed tablets but implementation of the aromatic ligand went along with reduction in hydrophilic properties. Disintegration time was prolonged more than 2-fold while water uptake capacity increased. Weight gain for Pec-Cys-MNA was at least 16-fold. Further, a sustained release of rosuvastatin calcium over 36 h was determined. Neither biodegradability nor CaCo-2 cell viability was affected. The study shows that Pec-Cys-MNA is a promising excipient for the development of mucoadhesive gastric dosage form.

  13. Effect of complexing agent on the photoelectrochemical properties of bath deposited CdS thin films

    NASA Astrophysics Data System (ADS)

    Patil, S. B.; Singh, A. K.

    2010-02-01

    In the present paper photoelectrochemical (PEC) performance of bath deposited CdS thin films based on complexing agents i.e. ammonia and triethanolamine (TEA) has been discussed. Effect of annealing has also been analyzed. The as-deposited and annealed (at 523 K for 1 h in air) films were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorption spectroscopy, SEM, electrochemical impedance spectroscopy (EIS), and PEC properties. XRD studies revealed that the films were nanocrystalline in nature with mixed hexagonal and cubic phases. TEA complex resulted in better crystallinity. Further improvement in the crystallinity of the films was observed after air annealing. The marigold flower-like structure, in addition to flakes morphology, was observed with TEA complex, whereas for ammonia complex only flakes morphology was observed. The UV-vis absorption studies revealed that the optical absorption edge for the films with ammonia and TEA complex was around 475 nm and 500 nm, respectively. Annealing of the films resulted in red shift in the UV-vis absorption. The PEC cell performance of CdS films was found to be strongly affected by crystallinity and morphology of the films resulted due to complexing agent and annealing. The air annealed film deposited using TEA complex showed maximum short circuit current density ( Jsc) and open circuit voltage ( Voc) i.e. 99 μA/cm 2 and 376 mV respectively, under 10 mW/cm 2 of illumination. The films deposited using TEA complex showed good stability under PEC cell conditions.

  14. Fabrication and applications of copper sulfide (CuS) nanostructures

    NASA Astrophysics Data System (ADS)

    Shamraiz, Umair; Hussain, Raja Azadar; Badshah, Amin

    2016-06-01

    This review article presents different fabrication procedures (under the headlines of solvothermal routes, aerosol methods, solution methods and thermolysis), and applications (photocatalytic degradation, ablation of cancer cells, electrode material in lithium ion batteries and in gas sensing, organic solar cells, field emission properties, super capacitor applications, photoelectrochemical performance of QDSCs, photocatalytic reduction of organic pollutants, electrochemical bio sensing, enhanced PEC characteristics of pre-annealed CuS film electrodes) of copper sulfide (Covellite).

  15. Risk assessment of marine environments from ballast water discharges with laboratory-scale hydroxyl radicals treatment in Tianjin Harbor, China.

    PubMed

    Zhang, Nahui; Zhang, Yubo; Bai, Mindong; Zhang, Zhitao; Chen, Cao; Meng, Xiangying

    2014-12-01

    For the majority of ballast water treatment system (BWTS) that employ active substances (e.g., oxidative compounds), relevant chemicals (RCs) formation is an issue owing to their potential adverse effects on aquatic organisms. Accordingly, BWTS must be approved by the International Maritime Organization (IMO), and the approval procedure requires environmental risk assessment. The most commonly employed harbor used to calculate predicted environmental concentrations (PECs) for RCs in treated ballast water is the GESAMP-BWWG (Group of Experts on Scientific Aspects of Marine Environmental Protection-Ballast Water Working Group) model harbor. However, there is very little assessment data available regarding the associated environmental impacts in ports and harbors of China. Therefore, in this study the concentration of fifteen RCs from the existing laboratory-scale BWTS using hydroxyl radicals was obtained and input into the MAMPEC (Marine Antifoulant Model to Predict Environmental Concentrations) model to compute PECs in Tianjin Harbor, China. The potential risks to the aquatic environment posed by treated ballast water in Tianjin Harbor were further assessed based on the calculated ratio of PECs and predicted no effect concentrations (PNECs). Only monochloroacetic acid and dichloroacetic acid were found to have potential risks, and the ratios of PECs and PNECs to the other measured RCs were less than 1, indicating that the environmental risk posed by treated ballast water discharged into Tianjin Harbor is of little concern. The concentration of total residual oxidant recommended by the IMO (<0.2 mg/L) in treated ballast water at discharge was found to be at levels that may pose a risk to the aquatic environment in Tianjin Harbor.

  16. A generalized in situ electrodeposition of Zn doped CdS-based photoelectrochemical strategy for the detection of two metal ions on the same sensing platform.

    PubMed

    Zhang, Yong; Ma, Hongmin; Wu, Dan; Li, Rongxia; Wang, Xueping; Wang, Yaoguang; Zhu, Wenjuan; Wei, Qin; Du, Bin

    2016-03-15

    An efficient strategy for the sensitive detection of Cd(2+) and Cu(2+) on the same sensing platform was first developed based on the photocurrents generated from the electrodeposited Zn doped CdS (CdZnS) film. The enhancement of the photocurrents, which was directly obtained from the in situ electrodeposited CdZnS on ITO with the gradual addition of Cd(2+), was used an indicator for the content of Cd(2+) with theoretical and technical simplicity. Moreover, the electrodeposited CdZnS was further applied to sensing of Cu(2+) based on the interaction between Cu(2+) and S(2-) by immersing the hetero-structural film electrode into a Cu(2+)-containing sample for an appropriate time, leading to decrease the photocurrent of CdZnS. The decrease extent of photocurrent was depended on the concentration of Cu(2+) in the sample solution. Due to the sensitivity of the photoelectrochemical (PEC) sensor was enhanced obviously through the doping of Zn, the present electrodeposited PEC method demonstrated acceptable linear range of 10(-9)-10(-2)M and 10(-8)-10(-4)M, with low detection limit down to 0.35 nM and 3 nM for Cd(2+) and Cu(2+) respectively, which were lower than the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The proposed CdZnS-based PEC strategy achieved two metal ions detection on the same sensing platform, which had positive and significant effect on solving the common problems, such as time-consuming, high cost, complex operation and high detection limit in the detection of metal ions. In addition, the proposed PEC device was further successfully applied to an assay of Cd(2+) and Cu(2+) in water sample. PMID:26528808

  17. Design, synthesis, evaluation and QSAR analysis of N(1)-substituted norcymserine derivatives as selective butyrylcholinesterase inhibitors.

    PubMed

    Takahashi, Jun; Hijikuro, Ichiro; Kihara, Takeshi; Murugesh, Modachur G; Fuse, Shinichiro; Kunimoto, Ryo; Tsumura, Yoshinori; Akaike, Akinori; Niidome, Tetsuhiro; Okuno, Yasushi; Takahashi, Takashi; Sugimoto, Hachiro

    2010-03-01

    We synthesized a series of N(1)-substituted norcymserine derivatives 7a-p and evaluated their anti-cholinesterase activities. In vitro evaluation showed that the pyridinylethyl derivatives 7m-o and the piperidinylethyl derivative 7p improved the anti-butyrylcholinesterase activity by approximately threefold compared to N(1)-phenethylnorcymserine (PEC, 2). A quantitative structure-activity relationship (QSAR) study indicated that logS might be a key feature of the improved compounds.

  18. Evaluation of numerical sediment quality targets for the St. Louis River Area of Concern

    USGS Publications Warehouse

    Crane, J.L.; MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Severn, C.G.; Berger, T.A.; Field, L.J.

    2002-01-01

    Numerical sediment quality targets (SQTs) for the protection of sediment-dwelling organisms have been established for the St. Louis River Area of Concern (AOC), 1 of 42 current AOCs in the Great Lakes basin. The two types of SQTs were established primarily from consensus-based sediment quality guidelines. Level I SQTs are intended to identify contaminant concentrations below which harmful effects on sediment-dwelling organisms are unlikely to be observed. Level II SQTs are intended to identify contaminant concentrations above which harmful effects on sediment-dwelling organisms are likely to be observed. The predictive ability of the numerical SQTs was evaluated using the matching sediment chemistry and toxicity data set for the St. Louis River AOC. This evaluation involved determination of the incidence of toxicity to amphipods (Hyalella azteca) and midges (Chironomus tentans) within five ranges of Level II SQT quotients (i.e., mean probable effect concentration quotients [PEC-Qs]). The incidence of toxicity was determined based on the results of 10-day toxicity tests with amphipods (endpoints: survival and growth) and 10-day toxicity tests with midges (endpoints: survival and growth). For both toxicity tests, the incidence of toxicity increased as the mean PEC-Q ranges increased. The incidence of toxicity observed in these tests was also compared to that for other geographic areas in the Great Lakes region and in North America for 10- to 14-day amphipod (H. azteca) and 10- to 14-day midge (C. tentans or C. riparius) toxicity tests. In general, the predictive ability of the mean PEC-Qs was similar across geographic areas. The results of these predictive ability evaluations indicate that collectively the mean PEC-Qs provide a reliable basis for classifying sediments as toxic or not toxic in the St. Louis River AOC, in the larger geographic areas of the Great Lakes, and elsewhere in North America.

  19. The cancer process as a type of immunocomplex hypersensibility involving C3b, natural killer cytotoxicity and antibody-dependent cell cytotoxicity: proposals for tumour immunotherapy and vaccine.

    PubMed

    Manzo, G

    1998-05-01

    I have previously assumed that stem tumour cells are 'para-embryonal cells' (PECs) poor or missing in major histocompatibility complex (MHC) antigens. PECs might induce adjoining differentiated hyperplastic cells to also express tumoral phenotype and properties, thus transforming them into 'differentiated para-embryonal cells' (DPECs), MHC-endowed. In such a way, PECs, MHC-lacking, would be automatically surrounded by DPECs, MHC-endowed: this tumour organization was experimentally found by Cordon-Cardo et al in a variety of cancers. Now, I suggest that such a tumour histology might preferentially induce an anti-DPEC T cell immune response which, sparing PECs, might release increasing amounts of DPEC antigens in the peritumour site. DPEC antigens might increase synthesis of specific antibodies and subsequent immunocomplex formation at the peritumour site. Here, abundant immunocomplexes might react through their Fc pieces with CD16 receptors of antibody-dependent cell cytotoxicity (ADCC)-endowed immune cells (natural killer (NK) cells, macrophages, polymorphonuclear cells). These cells would thus be stimulated to secrete their lytic factors before and without their coming into contact with target tumour cells. On the other hand, abundant immunocomplexes at the peritumour site might massively activate the complement system, thus generating large amounts of C3b. C3b might react with CD11b receptors of NK cells, stimulating them to also secrete their lytic factors in an ectopic way at the peritumour site, thus impairing NK cytotoxicity. In such a way, in the absence of ADCC and NK cytotoxicity, a tumour cell enhancement might easily occur. In the light of these ideas, a strategy for antitumour immunotherapy and vaccine is then proposed. PMID:9681920

  20. A generalized in situ electrodeposition of Zn doped CdS-based photoelectrochemical strategy for the detection of two metal ions on the same sensing platform.

    PubMed

    Zhang, Yong; Ma, Hongmin; Wu, Dan; Li, Rongxia; Wang, Xueping; Wang, Yaoguang; Zhu, Wenjuan; Wei, Qin; Du, Bin

    2016-03-15

    An efficient strategy for the sensitive detection of Cd(2+) and Cu(2+) on the same sensing platform was first developed based on the photocurrents generated from the electrodeposited Zn doped CdS (CdZnS) film. The enhancement of the photocurrents, which was directly obtained from the in situ electrodeposited CdZnS on ITO with the gradual addition of Cd(2+), was used an indicator for the content of Cd(2+) with theoretical and technical simplicity. Moreover, the electrodeposited CdZnS was further applied to sensing of Cu(2+) based on the interaction between Cu(2+) and S(2-) by immersing the hetero-structural film electrode into a Cu(2+)-containing sample for an appropriate time, leading to decrease the photocurrent of CdZnS. The decrease extent of photocurrent was depended on the concentration of Cu(2+) in the sample solution. Due to the sensitivity of the photoelectrochemical (PEC) sensor was enhanced obviously through the doping of Zn, the present electrodeposited PEC method demonstrated acceptable linear range of 10(-9)-10(-2)M and 10(-8)-10(-4)M, with low detection limit down to 0.35 nM and 3 nM for Cd(2+) and Cu(2+) respectively, which were lower than the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The proposed CdZnS-based PEC strategy achieved two metal ions detection on the same sensing platform, which had positive and significant effect on solving the common problems, such as time-consuming, high cost, complex operation and high detection limit in the detection of metal ions. In addition, the proposed PEC device was further successfully applied to an assay of Cd(2+) and Cu(2+) in water sample.

  1. How to become a uropathogen: Comparative genomic analysis of extraintestinal pathogenic Escherichia coli strains

    PubMed Central

    Brzuszkiewicz, Elzbieta; Brüggemann, Holger; Liesegang, Heiko; Emmerth, Melanie; Ölschläger, Tobias; Nagy, Gábor; Albermann, Kaj; Wagner, Christian; Buchrieser, Carmen; Emődy, Levente; Gottschalk, Gerhard; Hacker, Jörg; Dobrindt, Ulrich

    2006-01-01

    Uropathogenic Escherichia coli (UPEC) strain 536 (O6:K15:H31) is one of the model organisms of extraintestinal pathogenic E. coli (ExPEC). To analyze this strain's genetic basis of urovirulence, we sequenced the entire genome and compared the data with the genome sequence of UPEC strain CFT073 (O6:K2:H1) and to the available genomes of nonpathogenic E. coli strain MG1655 (K-12) and enterohemorrhagic E. coli. The genome of strain 536 is ≈292 kb smaller than that of strain CFT073. Genomic differences between both UPEC are mainly restricted to large pathogenicity islands, parts of which are unique to strain 536 or CFT073. Genome comparison underlines that repeated insertions and deletions in certain parts of the genome contribute to genome evolution. Furthermore, 427 and 432 genes are only present in strain 536 or in both UPEC, respectively. The majority of the latter genes is encoded within smaller horizontally acquired DNA regions scattered all over the genome. Several of these genes are involved in increasing the pathogens' fitness and adaptability. Analysis of virulence-associated traits expressed in the two UPEC O6 strains, together with genome comparison, demonstrate the marked genetic and phenotypic variability among UPEC. The ability to accumulate and express a variety of virulence-associated genes distinguishes ExPEC from many commensals and forms the basis for the individual virulence potential of ExPEC. Accordingly, instead of a common virulence mechanism, different ways exist among ExPEC to cause disease. PMID:16912116

  2. Using resources of public health centers for education and professional societies to incorporate homeland security topics into public teacher continuing education.

    PubMed

    McCarthy, Margaret E

    2003-08-01

    The Department of Education, the Association of Schools of Public Health, and national professional societies dedicated to teaching and dissemination of information for health and education in the public sector can form a clearinghouse on information and manpower on Homeland Security by affiliation with Centers for Public Health Preparedness (CPHP). The state licensed or regional societies can contribute further information and guidelines. In the HPS the Science Teacher Workshop (STW) and Public Education (PEC) Committees can assist a CPHP on radiation issues.

  3. How to become a uropathogen: comparative genomic analysis of extraintestinal pathogenic Escherichia coli strains.

    PubMed

    Brzuszkiewicz, Elzbieta; Brüggemann, Holger; Liesegang, Heiko; Emmerth, Melanie; Olschläger, Tobias; Nagy, Gábor; Albermann, Kaj; Wagner, Christian; Buchrieser, Carmen; Emody, Levente; Gottschalk, Gerhard; Hacker, Jörg; Dobrindt, Ulrich

    2006-08-22

    Uropathogenic Escherichia coli (UPEC) strain 536 (O6:K15:H31) is one of the model organisms of extraintestinal pathogenic E. coli (ExPEC). To analyze this strain's genetic basis of urovirulence, we sequenced the entire genome and compared the data with the genome sequence of UPEC strain CFT073 (O6:K2:H1) and to the available genomes of nonpathogenic E. coli strain MG1655 (K-12) and enterohemorrhagic E. coli. The genome of strain 536 is approximately 292 kb smaller than that of strain CFT073. Genomic differences between both UPEC are mainly restricted to large pathogenicity islands, parts of which are unique to strain 536 or CFT073. Genome comparison underlines that repeated insertions and deletions in certain parts of the genome contribute to genome evolution. Furthermore, 427 and 432 genes are only present in strain 536 or in both UPEC, respectively. The majority of the latter genes is encoded within smaller horizontally acquired DNA regions scattered all over the genome. Several of these genes are involved in increasing the pathogens' fitness and adaptability. Analysis of virulence-associated traits expressed in the two UPEC O6 strains, together with genome comparison, demonstrate the marked genetic and phenotypic variability among UPEC. The ability to accumulate and express a variety of virulence-associated genes distinguishes ExPEC from many commensals and forms the basis for the individual virulence potential of ExPEC. Accordingly, instead of a common virulence mechanism, different ways exist among ExPEC to cause disease.

  4. Pathogenicity-associated islands in extraintestinal pathogenic Escherichia coli are fitness elements involved in intestinal colonization.

    PubMed

    Diard, Médéric; Garry, Louis; Selva, Marjorie; Mosser, Thomas; Denamur, Erick; Matic, Ivan

    2010-10-01

    The virulence of many human pathogens does not seem to be an evolutionarily selected trait, but an accidental by-product of the selection that operates in another ecological context. We investigated the possibility that virulence of the extraintestinal pathogenic Escherichia coli (ExPEC) strains, which frequently cause disease in the host in which they asymptomatically colonize the intestine, is the consequence of commensalism. Most of the ExPEC virulence factors are clustered on genomic islands called pathogenicity-associated islands (PAIs). We constructed and characterized several mutants of the ExPEC 536 strain with either (i) deletions of each single PAI or (ii) a complete deletion of all seven PAIs. In vitro phenotypic characterization of 536 mutants showed that the seven PAIs were dispensable for growth in the absence of external stress, as well as under a range of biologically relevant stressors, i.e., serum, bile, and oxidative, nitrosative, hyperosmotic, and acidic stress. However, challenge against the wild-type (WT) strain in a murine model shows that the deletion of all seven PAIs drastically reduces the fitness of 536 during persistent intestinal colonization. This defect seems to be linked to the hypermotility observed for mutants devoid of all seven PAIs. In addition, we show that PAIs diminish fitness of their carrier during growth in urine, suggesting that urinary tract infections are unlikely to provide selective pressure for the maintenance of ExPEC PAIs. Our results are in accordance with the coincidental-evolution hypothesis postulating that extraintestinal E. coli virulence is a by-product of commensalism.

  5. Virulence genotypes, antibiotic resistance and the phylogenetic background of extraintestinal pathogenic Escherichia coli isolated from urinary tract infections of dogs and cats in Brazil.

    PubMed

    Osugui, L; de Castro, A F Pestana; Iovine, R; Irino, K; Carvalho, V M

    2014-06-25

    Urinary tract infection (UTI) is a frequent disease of humans and pets and has extra-intestinal pathogenic Escherichia coli (ExPEC) strains as one of the main etiologic agent. ExPEC are characterized by specific virulence factors and are related to a heterogeneous group of human and animal disorders, besides to be a relevant participant in the dissemination of antimicrobial resistance. The purpose of this study was to characterize E. coli strains isolated from UTI of dogs and cats for serotypes, virulence markers, phylogenetic groups and sensitivity to antimicrobial drugs. E. coli was identified as the etiologic agent of UTI in urine samples of 43 pets (7 cats and 36 dogs). Serogroups O2, O4 and O6 corresponded to more than one third of the isolates, being 62% of the total strains classified as B2, 18% as D, 16% as B1 and 4% as A. The iucD (22%), fyuA (80%), traT (51%) and cvaC (20%) genes were distributed among the four phylogenetic groups, whereas the papC/papEF (47%) and malX (67%) genes were found only in groups B2 and D. There were a high number of resistant strains, with 76% of the strains belonging to groups A, B1 and D characterized as multidrug resistant (MDR), whereas only 21% had this phenotype in the group B2. The ExPEC strains isolated in this study displayed pathotypic and phylogenetic similarities with human isolates and high percentages of drug resistance. The finding of MDR ExPEC strains suggests implications for animal and public health and deserves more investigations.

  6. Prominence of an O75 Clonal Group (Clonal Complex 14) among Non-ST131 Fluoroquinolone-Resistant Escherichia coli Causing Extraintestinal Infections in Humans and Dogs in Australia

    PubMed Central

    Trott, Darren J.; Johnson, James R.; Heisig, Peter; Heisig, Anke; Clabots, Connie R.; Johnston, Brian; Cobbold, Rowland N.

    2012-01-01

    Fluoroquinolone (FQ)-resistant extraintestinal pathogenic Escherichia coli (FQr ExPEC) strains from phylogenetic group B2 are undergoing epidemic spread. Isolates belonging to phylogenetic group B2 are generally more virulent than other E. coli isolates; therefore, resistance to FQs among group B2 isolates is concerning. Although clonal expansion of sequence type 131 (ST131) is a major factor, the contribution of additional clonal groups has not been quantified. Group B2 FQr ExPEC isolates from humans (n = 250) and dogs (n = 12) in Australia were screened for ST131, a recently recognized and rapidly emerging multidrug-resistant and virulent clonal group that is important in both human and companion animal medicine. Non-ST131 isolates underwent virulence genotyping, PCR-based O typing, partial multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and FQ resistance mechanism analysis. Of 49 non-ST131 isolates (45 human, 4 canine), 49% (24 human, 2 canine) represented O-type O75 and exhibited conserved virulence genotypes (F10 papA allele, iha, fimH, sat, vat, fyuA, iutA, kpsMII, usp, ompT, malX, K1/K5 capsule) and MLST allele profiles corresponding with clonal complex CC14. Two clusters, each containing canine and human isolates, were identified by PFGE (differentiated by K1 and K5 capsules). Australian FQr O75 isolates exhibited commonality with an historical FQ-susceptible O75 urosepsis isolate (also CC14). The isolation from humans and dogs of highly similar FQr derivatives of the classic O75:K1/K5 (CC14) ExPEC lineage suggests recent acquisition of FQ resistance and potential cross-host-species transfer. This lineage should be targeted with ST131 in future epidemiological investigations of FQr ExPEC. PMID:22526317

  7. Identification of potentially diarrheagenic atypical enteropathogenic Escherichia coli strains present in Canadian food animals at slaughter and in retail meats.

    PubMed

    Comery, Raven; Thanabalasuriar, Ajitha; Garneau, Philippe; Portt, Andrea; Boerlin, Patrick; Reid-Smith, Richard J; Harel, Josée; Manges, Amee R; Gruenheid, Samantha

    2013-06-01

    This study identified and characterized enteropathogenic Escherichia coli (EPEC) in the Canadian food supply. Eighteen of 450 E. coli isolates from food animal sources were identified as atypical EPEC (aEPEC). Several of the aEPEC isolates identified in this study possessed multiple virulence genes, exhibited adherence and attaching and effacing (A/E) lesion formation, disrupted tight junctions, and were coclassified with the extraintestinal pathogenic E. coli (ExPEC) and enterotoxigenic E. coli (ETEC) pathotypes. PMID:23584785

  8. Regulation and role in pathogenicity of Erwinia chrysanthemi 3937 pectin methylesterase.

    PubMed

    Boccara, M; Chatain, V

    1989-07-01

    The gene pem, encoding the pectin methylesterase (PME) of Erwinia chrysanthemi 3937, was cloned and mutagenized by mini-Mu transposable elements. A second gene, pecY, which could act as a negative regulator of PME was found 5' to the pem gene. A PME-E. chrysanthemi derivative inoculate onto Saintpaulia plants was shown to be clearly noninvasive, demonstrating the important role of this enzyme in soft rot disease. PMID:2738029

  9. Ab initio study on the low-lying excited states of gas-phase PH+ cation including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Li, Xia; Zhang, Xiaomei; Yan, Bing

    2015-05-01

    Ab initio calculations have been performed on the low-lying excited and ground states of PH+. The potential energy curves (PECs) of the Λ-S states were calculated with multi-reference configuration interaction (MRCI) method along with the basis sets at 5-ξ level. In order to improve the PECs, the Davidson(+Q) correction and the Scalar relativistic effect are included. The corresponding spectroscopic constants were determined and good agreements with the available measurement were found. The interactions of the A2Δ-4Π and 12Σ+-4Π by the spin-orbit coupling (SOC) effect were well described by the spin-orbit matrix elements. The SOC effect makes the original 8 Λ-S states split into 15 Ω states. The Ω = 1/2 state generated from the X2Π state is confirmed to the ground Ω state. And the SOC splitting for the X2Π is calculated to be 294 cm-1. The SOC effect has large effect on the PECs of the A2Δ and 12Σ+ states, leading to much more shallow potential wells as well as potential barriers. The analysis of the wavefunction for the Ω states shows that the strong spin-orbit interaction exists near the crossing points of the PECs for the Λ-S states. The transition dipole moments (TDMs) of transitions A2Δ-X2Π and 12Σ--X2Π are evaluated with the MRCI wavefunction. Based on the TDMs along with the calculated Franck-Condon factors, the radiative lifetimes for the selected vibrational levels of A2Δ and 12Σ- states are predicted at the microseconds (μs). Good agreement with the measurement shows that the lowest vibrational level for A2Δ state is almost uninfluenced by the perturbation via the SOC effect.

  10. Effect of surface deposits on electromagnetic waves propagating in uniform ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, Kenneth J.

    1990-01-01

    A finite-element Galerkin formulation was used to study the effect of material surface deposits on the reflective characteristics of straight uniform ducts with PEC (perfectly electric conducting) walls. Over a wide frequency range, the effect of both single and multiple surface deposits on the duct reflection coefficient were examined. The power reflection coefficient was found to be significantly increased by the addition of deposits on the wall.

  11. Percutaneous endoscopic colostomy: a useful technique when surgery is not an option

    PubMed Central

    Tun, Gloria; Bullas, Dominic; Bannaga, Ayman; Said, Elmuhtady M.

    2016-01-01

    Percutaneous endoscopic colostomy (PEC) is a minimally invasive endoscopic procedure that offers an alternative treatment for high-risk patients with sigmoid volvulus or intestinal pseudo-obstruction who have tried conventional treatment options without success or those who are unfit for surgery. The procedure acts as an irrigation or decompressing channel and provides colonic ‘fixation’ to the anterior abdominal wall. The risk of complications highlights the importance of informed consent for patients and relatives.

  12. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    PubMed Central

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as −0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at −0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under −0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  13. Preparation and characterization of Nano-graphite/TiO2 composite photoelectrode for photoelectrocatalytic degradation of hazardous pollutant.

    PubMed

    Li, Dong; Jia, Jialin; Zhang, Yuhang; Wang, Na; Guo, Xiaolei; Yu, Xiujuan

    2016-09-01

    Nano-graphite(Nano-G)/TiO2 composite photoelectrode was fabricated via sol-gel reaction, followed by the hot-press approach. The morphology, structure and light absorption capability of composite was characterized by various characterizations. The photoelectrochemical property and photoelectrocatalytic(PEC) activity of photoelectrode were also investigated. Results revealed that anatase TiO2 nanoparticles with an average diameter of 10nm were dispersed uniformly on the thickness of 2-3nm Nano-G, and TiOC bond was formed. The absorption edge of Nano-G/TiO2 photoelectrode was red-shifted towards low energy region and the enhanced visible light absorption was obtained. The charge transfer resistance of Nano-G/TiO2 photoelectrode was significantly decreased after the addition of Nano-G. And its transient photoinduced current was 10.5 times the value achieved using TiO2 electrode. Nano-G/TiO2 photoelectrode displayed greatly enhanced PEC activity of 99.2% towards the degradation of phenol, which was much higher than the 29.1% and 58.3% degradation seen on TiO2 and Nano-G electrode, respectively. The highly efficient and stable PEC activity of Nano-G/TiO2 photoelectrode was attributed to the synergy effect between photocatalysis and electrocatalysis, as well as enhanced light absorption ability and higher separation efficiency of photogenerated charge carriers. Moreover, contribution of series of reactive species to the PEC degradation of Nano-G/TiO2 photoelectrode was determined.

  14. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst.

    PubMed

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as -0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at -0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under -0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  15. Preparation and characterization of Nano-graphite/TiO2 composite photoelectrode for photoelectrocatalytic degradation of hazardous pollutant.

    PubMed

    Li, Dong; Jia, Jialin; Zhang, Yuhang; Wang, Na; Guo, Xiaolei; Yu, Xiujuan

    2016-09-01

    Nano-graphite(Nano-G)/TiO2 composite photoelectrode was fabricated via sol-gel reaction, followed by the hot-press approach. The morphology, structure and light absorption capability of composite was characterized by various characterizations. The photoelectrochemical property and photoelectrocatalytic(PEC) activity of photoelectrode were also investigated. Results revealed that anatase TiO2 nanoparticles with an average diameter of 10nm were dispersed uniformly on the thickness of 2-3nm Nano-G, and TiOC bond was formed. The absorption edge of Nano-G/TiO2 photoelectrode was red-shifted towards low energy region and the enhanced visible light absorption was obtained. The charge transfer resistance of Nano-G/TiO2 photoelectrode was significantly decreased after the addition of Nano-G. And its transient photoinduced current was 10.5 times the value achieved using TiO2 electrode. Nano-G/TiO2 photoelectrode displayed greatly enhanced PEC activity of 99.2% towards the degradation of phenol, which was much higher than the 29.1% and 58.3% degradation seen on TiO2 and Nano-G electrode, respectively. The highly efficient and stable PEC activity of Nano-G/TiO2 photoelectrode was attributed to the synergy effect between photocatalysis and electrocatalysis, as well as enhanced light absorption ability and higher separation efficiency of photogenerated charge carriers. Moreover, contribution of series of reactive species to the PEC degradation of Nano-G/TiO2 photoelectrode was determined. PMID:27149660

  16. Transient receptor potential melastatin 4 channel contributes to migration of androgen-insensitive prostate cancer cells

    PubMed Central

    Kilch, Tatiana; Jochum, Marcus Martin; Urban, Sabine Katharina; Jung, Volker; Stöckle, Michael; Rother, Karen; Greiner, Markus; Peinelt, Christine

    2015-01-01

    Impaired Ca2+ signaling in prostate cancer contributes to several cancer hallmarks, such as enhanced proliferation and migration and a decreased ability to induce apoptosis. Na+ influx via transient receptor potential melastatin 4 channel (TRPM4) can reduce store-operated Ca2+ entry (SOCE) by decreasing the driving force for Ca2+. In patients with prostate cancer, gene expression of TRPM4 is elevated. Recently, TRPM4 was identified as a cancer driver gene in androgen-insensitive prostate cancer. We investigated TRPM4 protein expression in cancer tissue samples from 20 patients with prostate cancer. We found elevated TRPM4 protein levels in prostatic intraepithelial neoplasia (PIN) and prostate cancer tissue compared to healthy tissue. In primary human prostate epithelial cells (hPEC) from healthy tissue and in the androgen-insensitive prostate cancer cell lines DU145 and PC3, TRPM4 mediated large Na+ currents. We demonstrated significantly increased SOCE after siRNA targeting of TRPM4 in hPEC and DU145 cells. In addition, knockdown of TRPM4 reduced migration but not proliferation of DU145 and PC3 cells. Taken together, our data identify TRPM4 as a regulator of SOCE in hPEC and DU145 cells, demonstrate a role for TRPM4 in cancer cell migration and suggest that TRPM4 is a promising potential therapeutic target. PMID:26496025

  17. Factors Affecting Detection of Hepatitis E Virus on Canadian Retail Pork Chops and Pork Livers Assayed Using Real-Time RT-PCR.

    PubMed

    Wilhelm, B J; Leblanc, D; Avery, B; Pearl, D L; Houde, A; Rajić, A; McEwen, S A

    2016-03-01

    We collected 599 Canadian retail pork chops and 283 pork livers routinely (usually weekly) from April 2011 to March 2012 using the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) retail sampling platform. Samples were assayed using validated real-time (q) reverse transcriptase polymerase chain reaction (RT-PCR) and nested classical RT-PCR for the detection of hepatitis E virus (HEV), porcine enteric calicivirus (PEC) and rotavirus (RV). The presence of Escherichia coli, Salmonella spp. and Campylobacter spp. was measured on a subset of our samples. Exact logistic regression models were fitted for predictors for HEV detection, for each assay. For both assays, sample type (pork chop versus liver) was a significant predictor for HEV RNA detection. For nested classical RT-PCR but not qRT-PCR, region of sample collection was a significant predictor (P = 0.008) of HEV detection. Odds of HEV detection were greatest in spring relative to other seasons. E. coli was a significant predictor for HEV RNA detection using the qRT-PCR (P = 0.03). Overall, the prevalence of E. coli, Salmonella spp. and Campylobacter spp. was significantly greater than HEV, PEC or RV on our retail pork samples. Our sparse data set for the detection of PEC and RV precluded modelling of risk factors for the detection of these viruses. PMID:26192650

  18. Determination of photoelectrochemical water oxidation intermediates on haematite electrode surfaces using operando infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Zandi, Omid; Hamann, Thomas W.

    2016-08-01

    Semiconductor electrodes capable of using solar photons to drive water-splitting reactions, such as haematite (α-Fe2O3), have been the subject of tremendous interest over recent decades. The surface has been found to play a significant role in determining the efficiency of water oxidation with haematite; however, previous works have only allowed hypotheses to be formulated regarding the identity of relevant surface species. Here we investigate the water-oxidation reaction on haematite using infrared spectroscopy under photoelectrochemical (PEC) water-oxidation conditions. A potential- and light-dependent absorption peak at 898 cm‑1 is assigned to a FeIV=O group, which is an intermediate in the PEC water-oxidation reaction. These results provide direct evidence of high-valent iron–oxo intermediates as the product of the first hole-transfer reaction on the haematite surface and represent an important step in establishing the mechanism of PEC water oxidation on semiconductor electrodes.

  19. A competitive photoelectrochemical assay for estradiol based on in situ generated CdS-enhanced TiO2.

    PubMed

    Li, Rongxia; Liu, Yixin; Yan, Tao; Li, Yueyun; Cao, Wei; Wei, Qin; Du, Bin

    2015-04-15

    A novel and simple photoelectrochemical (PEC) bioassay protocol for estradiol was proposed based on in situ generated CdS-enhanced TiO2 film via competitive strategy. The CdS was generated in situ by immediately dropping S(2-) onto the Cd(2+)-functionalized titanium phosphate nanoparticles (TiP@Cd(2+)). The TiO2 photoactive sensing film with countless active sites was obtained by calcination and further explored for estradiol (E2) capture. The TiP@Cd(2+) was used as labels and immobilized through affinity-specific binding with E2 on the surface of the electrode. Greatly enhanced sensitivity was achieved by using porous TiP nanoparticles as carriers to load a large amount of Cd(2+) and further for more CdS production through the S(2-) deposition. What's more, the photocurrent of CdS generated on the electrode surface could be significantly amplified by the coupling of CdS and TiO2, which could enhance the excitation and photo-to-electric conversion efficiency. Through the application of a competitive binding assay, the proposed biosensor showed high sensitivity with a detection limit down to 2pg/mL. This simple and fast PEC E2-sensing approach offers great promise to extend its application for the assay of small molecules of biomedical, food and environmental interest. Additionally, the strategy of employing in situ generated narrow-band gap semiconductors paves a new way for PEC sensing.

  20. Air pollution and urinary thioether excretion in children of Barcelona

    SciTech Connect

    Mallol, J.; Nogues, M.R. )

    1991-06-01

    The polluted environment found in highly industrialized areas and in big cities contains a great quantity of electrophilic (EC) and proelectrophilic (PEC) compounds, which largely contribute to the development of several pathological processes in humans. EC and PEC can be coupled to the cysteine moiety of glutathione spontaneously or by the glutathione S-transferase system (GST), giving nontoxic metabolites that can be eliminated as urinary thioethers (UT). Therefore one approach to establishing the degree of impact of EC and PEC on the human body is the analysis of UT in the population living in polluted environments. The work presented here has been carried out in the city of Barcelona with a group of 50 children living in a polluted area, over a 12-mo period. Our results demonstrate that UT are significantly higher when the amounts of air pollutants (AP) increase; although the level of contamination never exceeded the established safe limits, UT reached values similar to those found in people smoking more than 10 cigarettes/d. These results may contribute to establishing the maximal levels of contamination compatible with a healthy life, on the basis of patterns of true salubrity rather than on political and economic criteria.