Science.gov

Sample records for 1997-1999 melampsora-rost paa

  1. New Mexico aggregate production sites, 1997-1999

    USGS Publications Warehouse

    Orris, Greta J.

    2000-01-01

    This report presents data, including latitude and longitude, for aggregate sites in New Mexico that were believed to be active in the period 1997-1999. The data are presented in paper form in Part A of this report and as Microsoft Excel 97 and Data Interchange Format (DIF) files in Part B. The work was undertaken as part of the effort to update information for the National Atlas. This compilation includes data from: the files of U.S. Geological Survey (USGS); company contacts; the New Mexico Bureau of Mines and Mineral Resources, New Mexico Bureau of Mine Inspection, and the Mining and Minerals Division of the New Mexico Energy, Minerals and Natural Resources Department (Hatton and others, 1998); the Bureau of Land Management Information; and direct communications with some of the aggregate operators. Additional information on most of the sites is available in Hatton and others (1998).

  2. CHLORDANES IN THE MID-ATLANTIC ATMOSPHERE: NEW JERSEY 1997-1999

    EPA Science Inventory

    To characterize the atmospheric dynamics and behavior of chlordane compounds in the mid-Atlantic region of the United States, atmospheric concentrations were measured in 1997-1999 at three New Jersey locations as part of the New Jersey Atmospheric Deposition Network (NJADN) pro...

  3. NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

    NASA Technical Reports Server (NTRS)

    Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

    2000-01-01

    under NASA UARP and ACMAP in a document entitled, Research Summaries 1997- 1999. Part 2 is entitled Present State of Knowledge of the Upper Atmosphere 1999 An Assessment Report.

  4. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    PubMed

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2. PMID:26695157

  5. Multifunctional ORMOSIL and PAA nanoparticles

    NASA Astrophysics Data System (ADS)

    Gupta, Anurag; Rao, K. V. R.; Pera, Paula; Wang, Shouyan J.; Missert, Joseph R.; Ohulchanskyy, Tymish; Roy, Indrajit; Morgan, Janet; Prasad, Paras N.; Kopelman, Raoul; Pandey, Ravindra K.

    2009-06-01

    Various problems arising during molecular imaging of different fluoroprobes and metabolites used in PDT can be circumvented by focusing on multifunctional therapy agents. Thus an effective photo sensitizer coupled with other useful roles to play in PDT treatment make nanoparticles as a good vehicle for different delivery assuming multifunctional roles not only in PDT but also as therapeutic agents for targeted delivery. A new approach is the involving use of 100 nm NPs as photo sensitizers and/or imaging agents. In our Lab., we employ two such NPs and are ORMOSIL (organically Modified Silica) and PAA (Polyacrylamide) which are found to be biologically very safe without disturbing the therapeutic value. The size of the nanoparticles determined by TEM and Dynamic Light Scattering are ~30 nm. These NPs are taken up in conjunction with cyanine dye at near infra red as it has been reported in literature that encapsulated NPs shows very low singlet oxygen production compared with the post-loaded NPs though the reasons are not yet clear. Therefore, we investigated the idea of post-loading or adsorbing vis-a-vis encapsulation.

  6. NGAP: A (Brief) Update PaaS, IaaS, Onbording, and the Future

    NASA Technical Reports Server (NTRS)

    McLaughlin, Brett; Pawloski, Andrew

    2016-01-01

    NASA ESDIS has charged the EED2 program with delivering a NASA-compliant, secure, cloud-based platform for application hosting. More than just a move to the cloud, this has forced us to examine all aspects of application hosting, from resource management to system administration, patching to monitoring, deployment to multiple environments. The result of this mandate is NGAP, the NASA General Application Platform. In this presentation, we will also discuss the various applications we are supporting and targeting, and their architectures including NGAPs move to support both PaaS and IaaS architectures.

  7. Dynamic peracetic acid (PAA) exposure, a treatment strategy against ectoparasites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The search for alternative therapeutic agents is a difficult and laborious task. The use of peracetic acid (PAA) has recently been evaluated as an alternative compound for disinfection (Gustavino et al., 2005). In addition to having a broad antimicrobial spectrum, PAA does not contribute to the form...

  8. Protein-protein interactions in the β-oxidation part of the phenylacetate utilization pathway: crystal structure of the PaaF-PaaG hydratase-isomerase complex.

    PubMed

    Grishin, Andrey M; Ajamian, Eunice; Zhang, Linhua; Rouiller, Isabelle; Bostina, Mihnea; Cygler, Miroslaw

    2012-11-01

    Microbial anaerobic and so-called hybrid pathways for degradation of aromatic compounds contain β-oxidation-like steps. These reactions convert the product of the opening of the aromatic ring to common metabolites. The hybrid phenylacetate degradation pathway is encoded in Escherichia coli by the paa operon containing genes for 10 enzymes. Previously, we have analyzed protein-protein interactions among the enzymes catalyzing the initial oxidation steps in the paa pathway (Grishin, A. M., Ajamian, E., Tao, L., Zhang, L., Menard, R., and Cygler, M. (2011) J. Biol. Chem. 286, 10735-10743). Here we report characterization of interactions between the remaining enzymes of this pathway and show another stable complex, PaaFG, an enoyl-CoA hydratase and enoyl-Coa isomerase, both belonging to the crotonase superfamily. These steps are biochemically similar to the well studied fatty acid β-oxidation, which can be catalyzed by individual monofunctional enzymes, multifunctional enzymes comprising several domains, or enzymatic complexes such as the bacterial fatty acid β-oxidation complex. We have determined the structure of the PaaFG complex and determined that although individually PaaF and PaaG are similar to enzymes from the fatty acid β-oxidation pathway, the structure of the complex is dissimilar from bacterial fatty acid β-oxidation complexes. The PaaFG complex has a four-layered structure composed of homotrimeric discs of PaaF and PaaG. The active sites of PaaF and PaaG are adapted to accept the intermediary components of the Paa pathway, different from those of the fatty acid β-oxidation. The association of PaaF and PaaG into a stable complex might serve to speed up the steps of the pathway following the conversion of phenylacetyl-CoA to a toxic and unstable epoxide-CoA by PaaABCE monooxygenase. PMID:22961985

  9. Acute toxicity of peracetic acid (PAA) to Ichthyophthirius multifiliis theronts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is an antimicrobial disinfectant used in agriculture, food processing and medical facilities. It has recently been suggested as a means to control infestations of Ichthyophthirius multifiliis. The purpose of this study was to determine the acute toxicity of two products contai...

  10. Acute toxicity of peracetic acid (PAA) to fish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA; also called peroxyacetic acid) is a promising new aquatic disinfectant that has also been used to treat parasites and fungus. It is registered with the U.S. Environmental Protection Agency (EPA) as an antimicrobial compound approved for indoor use on hard, non-porous surfaces. T...

  11. PERI-ANESTHESIA ANAPHYLAXIS (PAA): WE STILL HAVE NOT STARTED POST-PAA TESTING FOR INCITING ANESTHESIA-RELATED ALLERGENS.

    PubMed

    Alshaeri, Taghreed; Gupta, Deepak; Nagabhushana, Ananthamurthy

    2016-02-01

    Anaphylaxis during anesthesia is uncommon. Diagnosis of peri-anesthesia anaphylaxis (PAA) requires anesthesia providers' vigilance for prompt diagnosis and treatment. In this case report, we present a challenging case with suspected PAA including its perioperative management, intensive care unit (ICU) course, and post-discharge follow-up. A 44-year-old female (body mass index = 26) presented for elective abdominal panniculectomy. Post-intubation, severe bronchospasm occurred that was non-responsive to nebulized albuterol and intravenous epinephrine. Continuous infusion of epinephrine was initiated. After aborting surgical procedure, the patient was transferred to ICU on continuous intravenous infusion of epinephrine. Venous blood sampling showed elevated troponin level. Echocardiography revealed ejection fraction of 25% suspicious of Takotsubo cardiomyopathy (mid cavitary variant). Tracheal extubation was only possible after three days. Subsequently, patient was discharged home with a cardiology follow-up appointment and a referral to an allergy specialist. Unfortunately at our institution (an academic university hospital in United States) along with neighboring institutions in near-by areas, the only allergy skin tests available are for local anesthetics and antibiotics, while neuromuscular blocking agents (NMBAs) cannot be tested (the suspected anaphylactic agent in our case was presumably rocuronium). In summary, PAA requires and responds to emergent diagnosis and immediate treatment; however there is still a long way to go to ensure post-PAA testing for inciting anesthesia-related allergens. PMID:27382817

  12. Electrospinning of Bioactive Dex-PAA Hydrogel Fibers

    NASA Astrophysics Data System (ADS)

    Louie, Katherine Boyook

    In this work, a novel method is developed for making nano- and micro-fibrous hydrogels capable of preventing the rejection of implanted materials. This is achieved by either (1) mimicking the native cellular environment, to exert fine control over the cellular response or (2) acting as a protective barrier, to camouflage the foreign nature of a material and evade recognition by the immune system. Comprehensive characterization and in vitro studies described here provide a foundation for developing substrates for use in clinical applications. Hydrogel dextran and poly(acrylic acid) (PAA) fibers are formed via electrospinning, in sizes ranging from nanometers to microns in diameter. While "as-electrospun" fibers are continuous in length, sonication is used to fragment fibers into short fiber "bristles" and generate nano- and micro- fibrous surface coatings over a wide range of topographies. Dex-PAA fibrous surfaces are chemically modified, and then optimized and characterized for non-fouling and ECM-mimetic properties. The non-fouling nature of fibers is verified, and cell culture studies show differential responses dependent upon chemical, topographical and mechanical properties. Dex-PAA fibers are advantageously unique in that (1) a fine degree of control is possible over three significant parameters critical for modifying cellular response: topography, chemistry and mechanical properties, over a range emulating that of native cellular environments, (2) the innate nature of the material is non-fouling, providing an inert background for adding back specific bioactive functionality, and (3) the fibers can be applied as a surface coating or comprise the scaffold itself. This is the first reported work of dex-PAA hydrogel fibers formed via electrospinning and thermal cross-linking, and unique to this method, no toxic solvents or cross-linking agents are needed to create hydrogels or for surface attachment. This is also the first reported work of using sonication to

  13. PAA/PEO comb polymer effects on the rheological property evolution in concentrated cement suspensions

    NASA Astrophysics Data System (ADS)

    Kirby, Glen Harold

    We have studied the behavior of polyelectrolyte-based comb polymers in dilute solution and on the rheological property evolution of concentrated Portland cement suspensions. These species consisted of charge-neutral, poly(ethylene oxide) (PEO) "teeth" grafted onto a poly(acrylic acid) (PAA) "backbone" that contains one ionizable carboxylic acid group (COOH) per monomer unit. As a benchmark, our observations were compared to those obtained for pure cement pastes and systems containing pure polyelectrolyte species, i.e., sulfonated naphthalene formaldehyde (SNF) and poly(acrylic acid) (PAA). The behavior of PAA/PEO comb polymers, SNF, and PAA in dilute solution was studied as a function of pH in the absence and presence of mono-, di-, and trivalent counterions. Light scattering and turbidity measurements were carried out to assess their hydrodynamic radius and stability in aqueous solution, respectively. PAA experienced large conformational changes as a function of solution pH and ionic strength. Moreover, dilute solutions of ionized SNF and PAA species became unstable in the presence of multivalent counterions due to ion-bridging interactions. PAA/PEO solutions exhibited enhanced stability relative to pure polyelectrolytes under analogous conditions. The charge neutral PEO teeth shielded the underlying PAA backbone from ion-bridging interactions. In addition, such species hindered conformational changes in solution due to steric interactions between adjacent teeth. A new oscillatory shear technique was developed to probe the rheological property evolution of concentrated cement systems. The rheological property evolution of ordinary and white Portland cement systems were studied in the absence and presence of pure polyelectrolytes and PAA/PEO comb polymers with a wide range of PAA backbone molecular weight, PEO teeth molecular weight, and acid:imide ratio. Cement-PAA suspensions experienced rapid irreversible stiffening and set at 6 min due to ion

  14. High strain-rate response of injectable PAA hydrogel.

    PubMed

    Lin, Hong-Ru; Wang, Shih-Han; Chiang, Chia-Chin; Juang, Yun-Ching; Yu, Fu-Ann; Tsai, Liren

    2015-01-01

    Hydrogel materials have been widely considered as potential soft tissue replacements because of their high permeability, hydrophilicity, and biocompatibility, as well as their low coefficient of friction. Injectable (thermo-responsive) hydrogels can provide support and cushioning at irregularly shaped disease sites, and are thus suitable for use in treating osteoarthritis or degenerative disc disease. However, while some injectable hydrogels have been proven to sustain human body weight during daily activities, their mechanical properties under harsh dynamic conditions have not been well documented. A specified injectable polyacrylic acid (PAA) hydrogel was prepared for this study. To simulate sudden impacts or unexpected shocks to the PAA hydrogel, the split Hopkinson pressure bar technique was utilized. The dynamic responses of various hydrogels at confined high strain rates (100-2590 s(-1)) were presented. Hydrogel specimens with 3.37, 6.75, and 13.5% acrylic acid (AAc) concentrations were tested in the following three different material conditions: raw, phosphate-buffered saline (PBS) swollen, and PBS swollen with elevated temperature (37 °C). The dynamic bulk moduli of the hydrogels varied from 1.55 to 47.8 MPa depending on the given hydrogel's AAc concentration and swollen condition. PMID:25816201

  15. Investigations of PAA degradation in aqueous solutions: Impacts of water hardness, salinity and DOC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is used in aquaculture under various conditions for disinfection purposes. However, there is lack of information about its environmental fate. Therefore, the impact of water hardness, salinity, and dissolved organic carbon (DOC) on PAA-degradation within 5 hours was investigat...

  16. Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The disinfection behaviour of peracetic acid (PAA) in recirculating aquaculture systems (RAS) was investigated. Peracetic acid is a strong oxidizing agent found in various concentrations in different products. Three Wofasteril PAA products (E400 (c), Lspecical; AC 150) were tested in vitro for the...

  17. Sanitizing with peracetic acid (PAA)- An alternative treatment to use in aquaculture ...?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of the lack of approved treatments for fish disease, disinfectants were tested to treat fish pathogens. One of these substances is peracetic acid (PAA). PAA is an agent used for disinfection in aquaculture, but it must be investigated thoroughly in order to mitigate diseases without harmful ...

  18. Human mesenchymal stem cell osteoblast differentiation, ECM deposition, and biomineralization on PAH/PAA polyelectrolyte multilayers.

    PubMed

    Pattabhi, Sudhakara Rao; Lehaf, Ali M; Schlenoff, Joseph B; Keller, Thomas C S

    2015-05-01

    Polyelectrolyte multilayer (PEMU) coatings built layer by layer with alternating pairs of polyelectrolytes can be tuned to improve cell interactions with surfaces and may be useful as biocompatible coatings to improve fixation between implants and tissues. Here, we show that human mesenchymal stromal cells (hMSCs) induced with bone differentiation medium (BDM) to become osteoblasts biomineralize crosslinked PEMUs built with the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(acrylic acid) (PAA). Degrees of hMSC osteoblast differentiation and surface biomineralization on the smooth PAH-terminated PEMUs (PAH-PEMUs) and microstructured PAA-terminated PEMUs (PAA-PEMUs) reflect differences in cell-deposited extracellular matrix (ECM). BDM-induced hMSCs expressed higher levels of the early osteoblast differentiation marker alkaline phosphatase and collagen 1 (COL1) sooner on PAA-PEMUs than on PAH-PEMUs. Cells on both types of PEMUs proceeded to express the later stage osteoblast differentiation marker bone sialoprotein (BSP), but the BDM-induced cells organized a more amorphous Collagen I and denser BSP localization on PAA-PEMUs than on PAH-PEMUs. These ECM properties correlated with greater biomineralization on the PAA-PEMUs than on PAH-PEMUs. Together, these results confirm the suitability of PAH/PAA PEMUs as a substrate for hMSC osteogenesis and highlight the importance of substrate effects on ECM organization and BSP presentation on biomineralization. PMID:25203301

  19. PAA: an R/bioconductor package for biomarker discovery with protein microarrays

    PubMed Central

    Turewicz, Michael; Ahrens, Maike; May, Caroline; Marcus, Katrin; Eisenacher, Martin

    2016-01-01

    Summary: The R/Bioconductor package Protein Array Analyzer (PAA) facilitates a flexible analysis of protein microarrays for biomarker discovery (esp., ProtoArrays). It provides a complete data analysis workflow including preprocessing and quality control, uni- and multivariate feature selection as well as several different plots and results tables to outline and evaluate the analysis results. As a main feature, PAA’s multivariate feature selection methods are based on recursive feature elimination (e.g. SVM-recursive feature elimination, SVM-RFE) with stability ensuring strategies such as ensemble feature selection. This enables PAA to detect stable and reliable biomarker candidate panels. Availability and implementation: PAA is freely available (BSD 3-clause license) from http://www.bioconductor.org/packages/PAA/. Contact: michael.turewicz@rub.de or martin.eisenacher@rub.de PMID:26803161

  20. Cloning and expression of the porcine attaching and effacing-associated (paa) gene of enteropathogenic Escherichia coli.

    PubMed

    Pereira, D A; Teixeira Florian, E C; Ono, M A; Rossi, C Nachi; Vidotto, O; Vidotto, M C

    2015-01-01

    Porcine enteropathogenic Escherichia coli (PEPEC) produce an outer membrane protein (intimin) called Paa (porcine attaching and effacing-associated), which is involved in the pathogenesis of E. coli in piglets with diarrhea. The paa gene of a PEPEC strain isolated in Paraná, Brazil, was amplified by polymerase chain reaction, sequenced, and cloned into the pTrcHisTOPO2 vector. The deduced amino acid sequence encoded by the paa gene of PEPEC from Paraná, Brazil, showed 99% homology to the sequences from other PEPEC strains. In this study, the overexpression of recombinant Paa (rPaa) using alternative induction strategies was attempted. The auto-induction protocol showed excellent results for rPaa protein production with 0.4% (w/v) lactose. The rPaa protein is insoluble and was purified with Triton X-100 wash as a total antigen. This method produced a relatively high yield of rPaa. rPaa was recognized by serum from pigs immunized with the PEPEC strain. These results suggest that rPaa could be included in the development of a vaccine against swine colibacillosis. PMID:26345788

  1. Pre/post-strike atmospheric assessment system (PAAS)

    SciTech Connect

    Peglow, S. G., LLNL; Molitoris, J. D., LLNL

    1997-02-03

    The Pre/Post-Strike Atmospheric Assessment System was proposed to show the importance of local meteorological conditions in the vicinity of a site suspected of storing or producing toxic agents and demonstrate a technology to measure these conditions, specifically wind fields. The ability to predict the collateral effects resulting from an attack on a facility containing hazardous materials is crucial to conducting effective military operations. Our study approach utilized a combination of field measurements with dispersion modeling to better understand which variables in terrain and weather were most important to collateral damage predictions. To develop the PAAS wind-sensing technology, we utilized a combination of emergent and available technology from micro-Doppler and highly coherent laser systems. The method used for wind sensing is to probe the atmosphere with a highly coherent laser beam. As the beam probes, light is back-scattered from particles entrained in the air to the lidar transceiver and detected by the instrument. Any motion of the aerosols with a component along the beam axis leads to a Doppler shift of the received light. Scanning in a conical fashion about the zenith results in a more accurate and two-dimensional measurement of the wind velocity. The major milestones in the benchtop system development were to verify the design by demonstrating the technique in the laboratory, then scale the design down to a size consistent with a demonstrator unit which could be built to take data in the field. The micro-Doppler heterodyne system we developed determines absolute motion by optically mixing a reference beam with the return signal and has shown motion sensitivity to better than 1 cm/s. This report describes the rationale, technical approach and laboratory testing undertaken to demonstrate the feasibility and utility of a system to provide local meteorological data and predict atmospheric particulate motion. The work described herein was funded by

  2. [The malaria situation in the Russian Federation (1997-1999)].

    PubMed

    Baranova, A M; Sergiev, V P

    2000-01-01

    Profound socio-economic changes within the CIS countries in the 1990s brought a lot of negative changes in malaria prevention in targeted countries. The previously stable connection and cooperation in prophylactic activities have been interrupted. Supply of antimalarials, insecticides and equipment had been stopped. Many qualified cadres in the sanitary-epidemiological services in the countries were lost. Because of difficult economic situation they had to change their occupation and place of job. After prolonged period of a stable benign epidemiological situation within Russia the number of imported cases started to grow up. The sharp increase of imported malaria cases from Azerbaijan and Tajikistan had been noticed since 1994 (Tab. 1). For the first time in the history of malaria registration the number of cases imported from the CIS countries has been exceeded the number of malaria cases imported from all other countries in the world in 1995. Later in the end of the 1990s the imported malaria cases has been registered in Russia from some other CIS countries apart from Azerbaijan and Tajikistan. There were malaria cases imported from Armenia (13 cases), Moldavia (2), Turkmenistan (2), and Uzbekistan (2) in 1998. The number of imported malaria cases in Russia in 1999 (Jan-July) is 437. There is no information about introduced or indigenous malaria cases registered until now] within Russia. There were 13 introduced malaria cases as the result of numerous imported ones. 13 introduced cases have been registered in 10 oblasts (administrative regions of Russia). This number has been increased to 53 (!) in 1998 in 20 oblasts. There was one local outbreak of P. vivax malaria in Izberbash settlement (Dagestan). Number of indigenous malaria cases were 5 (1996), 18 (1997), 1 (1998). The contra-epidemic measures in Izberbash have included active cases detection and treatment indoor insecticide spaying and one tour of mass primaguine treatment during interseasonal period of time. Additional indigenous cases after imported and introduced ones have been detected in Krasnodar (1 cases), Samara (1), Tolyaty (1), and Cherkessk (5) in 1998. One induced P. falciparum malaria case has been detected Moscow in 1998. Medical nurse from urological branch of the Moscow hospital No. 29 has penetrated by syringe needle her hand after performing of intravenous injection to the patient with imported P. falciparum malaria. No other induced cases have been detected. Because of local administrative problems with primaquine supply not all P. vivax malaria cases have received complete treatment. As the result of these events there was malaria relapsed cases registered every year. The actual number was 20 (1993), 37 (1994), 45 (1995), 59 (1996), 99 (1997). Due to late appearance of patient with P. falciparum malaria before medical staff and as a result late diagnosis and late and some time inappropriate treatment there were several lethal malaria cases registered [table: see text] every year. Inappropriate treatment means that treatment of P. falciparum malaria cases was consisted of chloroquine only. The cumulative number of lethal cases in 1994-1997 was 12, and the same number in 1998 was 6. One should mention that one lethal case in 1998 in Volgograd was due to P. vivax. The subject was chronic alcoholic and combination with P. vivax malaria brings him to death. Some calculation reveals the risk of resurgence of malaria in Russia. If one analyses all P. vivax imported cases from the point of view of time and place of detection the following picture would be emerged: 83% of all imported cases has been localized within cities, and 17% only--in rural areas. Half of the latter has been appeared during cold part of years when transmission was impossible. The result of approximately 200 imported cases has been appeared in a right time and place there were 75 introduced cases. PMID:10900914

  3. Involvement of the TetR-Type Regulator PaaR in the Regulation of Pristinamycin I Biosynthesis through an Effect on Precursor Supply in Streptomyces pristinaespiralis

    PubMed Central

    Zhao, Yawei; Feng, Rongrong; Zheng, Guosong; Tian, Jinzhong; Ruan, Lijun; Ge, Mei; Jiang, Weihong

    2015-01-01

    ABSTRACT Pristinamycin I (PI), produced by Streptomyces pristinaespiralis, is a streptogramin type B antibiotic, which contains two proteinogenic and five aproteinogenic amino acid precursors. PI is coproduced with pristinamycin II (PII), a member of streptogramin type A antibiotics. The PI biosynthetic gene cluster has been cloned and characterized. However, thus far little is understood about the regulation of PI biosynthesis. In this study, a TetR family regulator (encoded by SSDG_03033) was identified as playing a positive role in PI biosynthesis. Its homologue, PaaR, from Corynebacterium glutamicum serves as a transcriptional repressor of the paa genes involved in phenylacetic acid (PAA) catabolism. Herein, we also designated the identified regulator as PaaR. Deletion of paaR led to an approximately 70% decrease in PI production but had little effect on PII biosynthesis. Identical to the function of its homologue from C. glutamicum, PaaR is also involved in the suppression of paa expression. Given that phenylacetyl coenzyme A (PA-CoA) is the common intermediate of the PAA catabolic pathway and the biosynthetic pathway of l-phenylglycine (l-Phg), the last amino acid precursor for PI biosynthesis, we proposed that derepression of the transcription of paa genes in a ΔpaaR mutant possibly diverts more PA-CoA to the PAA catabolic pathway, thereby with less PA-CoA metabolic flux toward l-Phg formation, thus resulting in lower PI titers. This hypothesis was verified by the observations that PI production of a ΔpaaR mutant was restored by l-Phg supplementation as well as by deletion of the paaABCDE operon in the ΔpaaR mutant. Altogether, this study provides new insights into the regulation of PI biosynthesis by S. pristinaespiralis. IMPORTANCE A better understanding of the regulation mechanisms for antibiotic biosynthesis will provide valuable clues for Streptomyces strain improvement. Herein, a TetR family regulator PaaR, which serves as the repressor of the

  4. Acute toxicity of peracetic acid (PAA) formulations to Ichthyophthirius multifiliis theronts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is an antimicrobial disinfectant used in agriculture, food processing and medical facilities. It has recently been suggested as a means to control infestations of Ichthyophthirius multifiliis. The purpose of this study was to determine the acute toxicity of two products contai...

  5. Microbial reduction in wastewater treatment using Fe(3+) and Al(3+) coagulants and PAA disinfectant.

    PubMed

    Pradhan, Surendra K; Kauppinen, Ari; Martikainen, Kati; Pitkänen, Tarja; Kusnetsov, Jaana; Miettinen, Ilkka T; Pessi, Matti; Poutiainen, Hannu; Heinonen-Tanski, Helvi

    2013-12-01

    Wastewater is an important source of pathogenic enteric microorganisms in surface water and a major contaminating agent of drinking water. Although primary and secondary wastewater treatments reduce the numbers of microorganisms in wastewater, significant numbers of microbes can still be present in the effluent. The aim of this study was to test the feasibility of tertiary treatment for municipal wastewater treatment plants (WWTPs) using PIX (FeCl3) or PAX (AlCl3) coagulants and peracetic acid (PAA) the disinfectant to reduce microbial load in effluent. Our study showed that both PIX and PAX efficiently reduced microbial numbers. PAA disinfection greatly reduced the numbers of culturable indicator microorganisms (Escherichia coli, intestinal enterococci, F-specific RNA coliphages and somatic DNA coliphages). In addition, pathogenic microorganisms, thermotolerant Campylobacter, Salmonella and norovirus GI, were successfully reduced using the tertiary treatments. In contrast, clostridia, Legionella, rotavirus, norovirus GII and adenovirus showed better resistance against PAA compared to the other microorganisms. However, interpretation of polymerase chain reaction (PCR) analysis results will need further studies to clarify the infectivity of the pathogenic microbes. In conclusion, PIX and PAX flocculants followed by PAA disinfectant can be used as a tertiary treatment for municipal WWTP effluents to reduce the numbers of indicator and pathogenic microorganisms. PMID:24334832

  6. In vivo kinetic analysis of the penicillin biosynthesis pathway using PAA stimulus response experiments.

    PubMed

    Deshmukh, Amit T; Verheijen, Peter J T; Maleki Seifar, Reza; Heijnen, Joseph J; van Gulik, Walter M

    2015-11-01

    In this study we combined experimentation with mathematical modeling to unravel the in vivo kinetic properties of the enzymes and transporters of the penicillin biosynthesis pathway in a high yielding Penicillium chrysogenum strain. The experiment consisted of a step response experiment with the side chain precursor phenyl acetic acid (PAA) in a glucose-limited chemostat. The metabolite data showed that in the absence of PAA all penicillin pathway enzymes were expressed, leading to the production of a significant amount of 6-aminopenicillanic acid (6APA) as end product. After the stepwise perturbation with PAA, the pathway produced PenG within seconds. From the extra- and intracellular metabolite measurements, hypotheses for the secretion mechanisms of penicillin pathway metabolites were derived. A dynamic model of the penicillin biosynthesis pathway was then constructed that included the formation and transport over the cytoplasmic membrane of pathway intermediates, PAA and the product penicillin-G (PenG). The model parameters and changes in the enzyme levels of the penicillin biosynthesis pathway under in vivo conditions were simultaneously estimated using experimental data obtained at three different timescales (seconds, minutes, hours). The model was applied to determine changes in the penicillin pathway enzymes in time, calculate fluxes and analyze the flux control of the pathway. This led to a reassessment of the in vivo behavior of the pathway enzymes and in particular Acyl-CoA:Isopenicillin N Acyltransferase (AT). PMID:26476338

  7. Crystal structure of phenylacetic acid degradation protein PaaG from Thermus thermophilus HB8.

    PubMed

    Kichise, Tomoyasu; Hisano, Tamao; Takeda, Kazuki; Miki, Kunio

    2009-09-01

    Microbial degradation of phenylacetic acid proceeds via the hybrid pathway that includes formation of a coenzyme A thioester, ring hydroxylation, non-oxygenolytic ring opening, and beta-oxidation-like reactions. A phenylacetic acid degradation protein PaaG is a member of the crotonase superfamily, and is a candidate non-oxygenolytic ring-opening enzyme. The crystal structure of PaaG from Thermus thermophilus HB8 was determined at a resolution of 1.85 A. PaaG consists of three identical subunits related by local three-fold symmetry. The monomer is comprised of a spiral and a helical domain with a fold characteristic of the crotonase superfamily. A putative active site residue, Asp136, is situated in an active site cavity and surrounded by several hydrophobic and hydrophilic residues. The active site cavity is sufficiently large to accommodate a ring substrate. Two conformations are observed for helix H2 located adjacent to the active site. Helix H2 is kinked at Asn81 in two subunits, whereas it is kinked at Leu77 in the other subunit, and the side chain of Tyr80 is closer to Asp136. This indicates that catalytic reaction of PaaG may proceed with large conformational changes at the active site. Asp136 is the only conserved polar residue in the active site. It is located at the same position as those of 4-chlorobenzoyl-CoA dehalogenase and peroxisomal Delta(3),Delta(2)-enoyl-CoA isomerase, indicating that PaaG may undergo isomerization or a ring-opening reaction via a Delta(3),Delta(2)-enoyl-CoA isomerase-like mechanism. PMID:19452559

  8. Bio-inspired self-cleaning PAAS hydrogel released coating for marine antifouling.

    PubMed

    Xue, Lili; Lu, Xili; Wei, Huan; Long, Ping; Xu, Jina; Zheng, Yufeng

    2014-05-01

    In this paper, an antifouling hydrogel coating of slippery hydrogel-released hydrous surface (SHRHS) with the self-cleaning ability of oil-resistance and self-regeneration characters was designed. A physical blending method of loading Sodium polyacrylate (PAAS) powder into the organic silicon resin was employed to prepare the SHRHS coating. The oil-resistance of the intact and scratch SHRHS coatings was performed by time-sequence images of washing dyed beef tallow stain away. The results showed that the SHRHS coating has the greater ability of stain removal. The concentration of Na+ ions released from PAAS hydrogel on the surface of the SHRHS coating was investigated by ion chromatograph (IC). The results revealed that the coating had the ability of self-regeneration by PAAS hydrogel continuously peeling. The biomass of two marine microalgae species, Nitzschia closterium f. minutissima and Navicula climacospheniae Booth attached on the SHRHS was investigated using UV-Visible Spectrophotometer (UV) and Scanning electron microscopy (SEM). The results showed that the microalgaes attached a significantly lower numbers on the SHRHS in comparison with the organic silicon coating. In order to confirm the antifouling ability of the SHRHS coating, the field trials were carried out for 12weeks. It showed that the SHRHS may provide an effective attachment resistance to reduce biofouling. PMID:24594048

  9. Chemical Analysis and Aqueous Solution Properties of Charged Amphiphilic Block Copolymers PBA-b-PAA Synthesized by MADIX

    SciTech Connect

    Jacquin,M.; Muller, P.; Talingting-Pabalan, R.; Cottet, H.; Berret, J.; Futterer, T.; Theodoly, O.

    2007-01-01

    We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter ?PBA/PAA, determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by liquid chromatography at the point of exclusion and adsorption transition, LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA-b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur.

  10. Synthesis and high-efficiency methylene blue adsorption of magnetic PAA/MnFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Ding, Zui; Cai, Minhan; Jian, Haitao; Zeng, Zhiqiao; Li, Feng; Liu, J. Ping

    2015-08-01

    MnFe2O4 nanoparticles and polyacrylic acid PAA/MnFe2O4 nanocomposites were synthesized by a hydrothermal method and ultrasonic mixing process. The obtained materials were characterized by XRD, FTIR, SEM, TEM, and VSM. XRD patterns indicate that the synthesized MnFe2O4 nanoparticles have a single cubic spinel phase. SEM images confirm the existence of three types of basic morphology of MnFe2O4 nanoparticles: octahedral, flower-like, and plate-like particles. High saturation magnetization Ms (up to 74.6 emu/g) of the as-synthesized MnFe2O4 nanoparticles was obtained. Experiments demonstrate that the variation of the hydrothermal reaction time does not remarkably affect the magnetic properties of MnFe2O4 nanoparticles. In PAA/MnFe2O4 nanocomposites, the coating of PAA leads to a slight decrease in magnetization of MnFe2O4 nanoparticles. Additionally, PAA coating greatly enhances the adsorption properties of MnFe2O4 nanoparticles for Methylene Blue (MB) dye. Especially, the removal efficiency reaches 96.3%. This research indicates that the as-synthesized PAA/MnFe2O4 nanocomposites exhibit excellent magnetic properties and can be taken as a promising adsorbent for removal of MB dye in industrial scale.

  11. Coupling High-Energy Radiography And Photon Activation Analysis (PAA) To Optimize The Characterization Of Nuclear Waste Packages

    SciTech Connect

    Carrel, F.; Agelou, M.; Gmar, M.; Laine, F.; Lamotte, T.; Lazaro, D.; Poumarede, B.; Rattoni, B.

    2009-12-02

    Radiological characterization of nuclear waste packages is an industrial issue in order to select the best mode of storage. The alpha-activity, mainly due to the presence of actinides ({sup 235}U, {sup 238}U, {sup 239}Pu,...) inside the package, is one of the most important parameter to assess during the characterization. Photon Activation Analysis (PAA) is a non-destructive active method (NDA method) based on the photofission process and on the detection of delayed particles (neutrons and gammas). This technique is well-adapted to the characterization of large concrete waste packages. However, PAA methods often require a simulation step which is necessary to analyze experimental results and to quantify the global mass of actinides. The weak point of this approach is that characteristics of the package are often not well-known, these latter having a huge impact on the final simulation result. High-energy radiography, based on the use of a linear electron accelerator (LINAC), allows to visualize the content of the package and is also a performing way to tune simulation models and to optimize the characterization process by PAA. In this article, we present high-energy radiography results obtained for two different large concrete waste packages in the SAPHIR facility (Active Photon and Irradiation System). This facility is dedicated to PAA study and development and setup for a decade in CEA Saclay. We also discuss possibilities offered by the coupling between high-energy radiography and PAA techniques.

  12. Liquid crystal-based glucose biosensor functionalized with mixed PAA and QP4VP brushes.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-06-15

    4-Cyano-4'-pentylbiphenyl (5CB) in a transmission electron microscopy (TEM) grid was developed for glucose detection by coating with a monolayer of mixed polymer brushes using poly(acrylicacid-b-4-cynobiphenyl-4'-oxyundecylacrylate) (PAA-b-LCP) and quaternized poly(4-vinylpyridine-b-4-cynobiphenyl-4'-oxyundecylacrylate) (QP4VP-b-LCP) (LCP stands for liquid crystal polymer) at the 5CB/aqueous interface. The resultant 5CB in TEM grid was functionalized with the PAA and QP4VP brushes, which were strongly anchored by the LCP block. The PAA brush rendered the 5CB/aqueous interface pH-responsive and the QP4VP brush immobilized glucose oxidase (GOx) through electrostatic interactions without the aid of coupling agents. The glucose was detected through a homeotropic-to-planar orientational transition of the 5CB observed through a polarized optical microscope (POM) under crossed polarizers. The optimum immobilization with a 0.78 µM GOx solution on the dual-brush-coated TEM grid enabled glucose detection at concentrations higher than 0.5 mM with response times shorter than 180 s. This TEM grid glucose sensor provided a linear response of birefringence of the 5CB to glucose concentrations ranging from 0.5 to 11 mM with a Michaelis-Menten constant (Km) of 1.67 mM. This new and sensitive glucose biosensor has the advantages of low production cost, simple enzyme immobilization, high enzyme sensitivity and stability, and easy detection with POM, and may be useful for prescreening the glucose level in the human body. PMID:25617751

  13. Grafting mechanism of electrochromic PAA-WO{sub 3} composite film

    SciTech Connect

    Choy, J.H.; Kim, Y.I.; Kim, B.W.; Campet, G.; Portier, J.; Huong, P.V.

    1999-02-01

    A micro-Raman spectroscopic study has been carried out to investigate the electrochromic process in a porous and nanocrystalline tungsten oxide film. The film was prepared by dipping the tin-doped indium oxide glass into an aqueous mixture solution of PAA (polyacrylic acid) and WO{sub 3}-NH{sub 4}OH. After heating at low temperature, around 100 C, the film was treated in 1 N HCl in order to achieve polycondensation, where the ammonium ion was replaced with a proton. In the micro-Raman spectra for the bleached and colored PAA-WO{sub 3} films, it was evident that the coloration accompanies a peak reduction at {approximately}960 cm{sup {minus}1} and a peak enhancement at {approximately}810 cm{sup {minus}1}. Based upon the present Raman observation, the authors can confirm that the electrochromism of the nanocrystalline tungsten oxide is dominated by the grafting process, i.e., the surface modification of {single_bond}W{sup VI}{double_bond}O bonds into {single_bond}W{sup V}{double_bond}O{sup (1{minus}{delta})+}{emdash}M{sup {delta}+} (M = H, Li) ones.

  14. Hygienisierung in der Fischzucht mittels Per-essigsäure (Disinfection of water with PAA: State of the investigations)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are very few therapeutic agents against aquaculture ectoparasites in Germany. Peracetic Acid (PAA) has been referred to as the best disinfective agent in the world, but it has not been used much here in aquaculture. We currently use this compound in ‘treatment crisis’ situations because ther...

  15. Nanoparticle Loading Induced Morphological Transitions and Size Fractionation of Coassemblies from PS-b-PAA with Quantum Dots.

    PubMed

    Liu, Wei; Mao, Jun; Xue, Yanhu; Zhao, Ziliang; Zhang, Haishan; Ji, Xiangling

    2016-08-01

    Inorganic nanoparticles play a very important role in the fabrication and regulation of desirable hybrid structures with block copolymers. In this study, polystyrene-b-poly(acrylic acid) (PS48-b-PAA67) and oleic acid-capped CdSe/CdS core/shell quantum dots (QDs) are coassembled in tetrahydrofuran (THF) through gradual water addition. QDs are incorporated into the hydrophilic PAA blocks because of the strong coordination between PAA blocks and the surface of QDs. Increasing the weight fraction of QDs (ω = 0-0.44) leads to morphological transitions from hybrid spherical micelles to large compound micelles (LCMs) and then to bowl-shaped structures. The coassembly process is monitored using transmission electron microscopy (TEM). Formation mechanism of different morphologies is further proposed in which the PAA blocks bridging QDs manipulates the polymer chain mobility and the resulting morphology. Furthermore, the size and size distribution of assemblies serving as drug carriers will influence the circulation time, organ distribution and cell entry pathway of assemblies. Therefore, it is important to prepare or isolate assemblies with monodisperse or narrow size distribution for biomedical applications. Here, the centrifugation and membrane filtration techniques are applied to fractionate polydisperse coassemblies, and the results indicate that both techniques provide effective size fractionation. PMID:27447738

  16. Salinity, water hardness, and dissolved organic carbon modulate degradation of peracetic acid (PAA) compounds in aqueous solutions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is used in aquaculture under different conditions for disinfection purposes. However, there is a lack of information about its environmental fate, particularly its persistence in aquatic systems with different chemistries. Therefore, the impact of water hardness, salinity, and d...

  17. Microfluidic formation of pH responsive 5CB droplets decorated with PAA-b-LCP.

    PubMed

    Khan, Waliullah; Choi, Jin Ho; Kim, Gyu Man; Park, Soo-Young

    2011-10-21

    We are reporting for the first time the pH responsiveness of liquid crystal (LC) microdroplets decorated with an amphiphilic block copolymer of PAA-b-LCP. We successfully demonstrated the adsorption of block copolymer on LC droplets by fluorescence microscopy and pH response to the radial-to-bipolar orientational change of the LC droplets by changing pH from 12 to 2 through the polarized optical microscope (POM). We believe that our results may pave the way for the generation of monodisperse droplets decorated by various amphiphilic block copolymers which respond to several kinds of the external stimuli. These developments may be important for potential applications of the LC droplets in sensing and encapsulation fields. PMID:21874196

  18. Synthesis and self-assembly of PAMAM/PAA Janus dendrimers

    NASA Astrophysics Data System (ADS)

    Gao, Chunmei; Liu, Mingzhu; Lü, Shaoyu; Zhang, Xinjie; Chen, Yuanmou

    2014-03-01

    Janus dendrimers have two differently functionalized segments which are located on opposite sides. They have many excellent properties and broad application prospects. In this study, poly(amido amine)/poly(acrylic acid) (PAMAM/PAA) Janus dendrimers were prepared by click chemistry. One of the first steps taken was the synthesis of N-Boc-G3.0 PAMAM dendrimers with primary amine groups at the periphery. Second, by amide coupling between propargylic acid and N-Boc-G3.0 PAMAM, PAMAM dendrimers with alkyne were successfully synthesized. After being dissolved in aqueous solutions with different pH, Janus dendrimers spontaneously form flowerlike micellar, Janus particles, and spherical micelles due to primary amino, tertiary amino, and carboxyl groups in the dendrimers. This self-assembly behavior depending on pH changes has a number of potential applications in the field of materials.

  19. Covalently-layers of PVA and PAA and in situ formed Ag nanoparticles as versatile antimicrobial surfaces.

    PubMed

    Fragal, Vanessa H; Cellet, Thelma S P; Pereira, Guilherme M; Fragal, Elizângela H; Costa, Marco Antonio; Nakamura, Celso Vataru; Asefa, Tewodros; Rubira, Adley F; Silva, Rafael

    2016-10-01

    The in situ synthesis of silver nanoparticles (AgNPs) within covalently-modified poly(ethylene terephthalate) (PET) films possessing ultra-thin layer of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) is successfully demonstrated. The resulting polymeric films are shown to exhibit antimicrobial activities toward Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and fungus (Candida albicans). To make the films, first PET surfaces were subject to photo-oxidation and subsequent solid-state grafting to attach a PVA layer, followed by a PAA layer. To synthesize the AgNPs inside the films, the PVA and PAA-modified PET was soaked in AgNO3 solution and the polymeric film was modified with the Ag(+) ions via Ag(+)-carboxylate interaction, and then the Ag(+) ions-containing polymer film was subject to either photo-reduction or thermal reduction processes. The PVA and PAA thin layers attached by covalent bonds to the PET surface uniquely promoted not only the in situ synthesis but also the stabilization of AgNPs. The formation of the AgNPs was confirmed by UV-vis spectroscopy or by monitoring the surface plasmon resonance (SPR) peak associated with AgNPs. The resulting PVA and PAA ultrathin layers modified and AgNPs containing PET served as bactericide and fungicide, inhibiting the growth of bacteria and fungi on the surfaces. Given PET's versatility and common use in many commercial processes, the method can be used for producing plastic surfaces with versatile antimicrobial and antibacterial properties. PMID:27196366

  20. Crystallization and preliminary X-ray analysis of two variants of the Escherichia coli O157 ParE2-PaaA2 toxin-antitoxin complex.

    PubMed

    Sterckx, Yann G J; Haesaerts, Sarah; Van Melderen, Laurence; Loris, Remy

    2014-09-01

    The paaR2-paaA2-parE2 operon is a three-component toxin-antitoxin module encoded in the genome of the human pathogen Escherichia coli O157. The toxin (ParE2) and antitoxin (PaaA2) interact to form a nontoxic toxin-antitoxin complex. In this paper, the crystallization and preliminary characterization of two variants of the ParE2-PaaA2 toxin-antitoxin complex are described. Selenomethionine-derivative crystals of the full-length ParE2-PaaA2 toxin-antitoxin complex diffracted to 2.8 Å resolution and belonged to space group P41212 (or P43212), with unit-cell parameters a = b = 90.5, c = 412.3 Å. It was previously reported that the full-length ParE2-PaaA2 toxin-antitoxin complex forms a higher-order oligomer. In contrast, ParE2 and PaaA213-63, a truncated form of PaaA2 in which the first 12 N-terminal residues of the antitoxin have been deleted, form a heterodimer as shown by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. Crystals of the PaaA213-63-ParE2 complex diffracted to 2.7 Å resolution and belonged to space group P6122 (or P6522), with unit-cell parameters a = b = 91.6, c = 185.6 Å. PMID:25195911

  1. Pervaporation separation of binary organic-aqueous liquid mixtures using crosslinked PVA membranes. I. Characterization of the reaction between PVA and PAA

    SciTech Connect

    Jiwon Rhim; Kewho Lee . Membranes and Separation Lab.); Minyoung Sohn; Hyeokjong Joo . Dept. of Polymer Science and Engineering)

    1993-10-20

    For the purpose of the water-selective membrane material development for pervaporation separation, poly(vinyl alcohol) (PVA) was crosslinked with a low molecular weight of poly(acrylic acid) (PAA). The crosslinking reactions between PVA and PAA were characterized through IR spectroscopy, differential scanning calorimetry (DSC), and tensile tests when varying the reaction conditions, that is, time, temperature, amounts of cross-linking agents, PAA. It was found that the crosslinking reaction was fast: in other words, that the reaction mainly occurred at the initial step of each reaction condition. The best reaction conditions for preparing the crosslinked PVA membranes were found to be: reaction time not over 1 h, reaction temperature in the range of 150-180 C. PAA contents of 15-20 wt% were found satisfactory with respect to the application areas.

  2. The ParE2–PaaA2 toxin–antitoxin complex from Escherichia coli O157 forms a heterodocecamer in solution and in the crystal

    PubMed Central

    Sterckx, Yann G. J.; Garcia-Pino, Abel; Haesaerts, Sarah; Jové, Thomas; Geerts, Lieselotte; Sakellaris, Viktor; Van Melderen, Laurence; Loris, Remy

    2012-01-01

    Escherichia coli O157 paaR2-paaA2-parE2 constitutes a unique three-component toxin–antitoxin (TA) module encoding a toxin (ParE2) related to the classic parDE family but with an unrelated antitoxin called PaaA2. The complex between PaaA2 and ParE2 was purified and characterized by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. It consists of a particle with a radius of gyration of 3.95 nm and is likely to form a heterododecamer. Crystals of the ParE2–PaaA2 complex diffract to 3.8 Å resolution and belong to space group P3121 or P3221, with unit-cell parameters a = b = 142.9, c = 87.5 Å. The asymmetric unit is consistent with a particle of around 125 kDa, which is compatible with the solution data. Therefore, the ParE2–PaaA2 complex is the largest toxin–antitoxin complex identified to date and its quaternary arrangement is likely to be of biological significance. PMID:22684081

  3. Kinetics of temperature response of PEO-b-PNIPAM-b-PAA triblock terpolymer aggregates and of their complexes with lysozyme

    DOE PAGESBeta

    Papagiannopoulos, Aristeidis; Meristoudi, Anastasia; Hong, Kunlun; Pispas, Stergios

    2015-12-18

    We present the kinetics of temperature response of a PEO-b-PNIPAM-b-PAA triblock terpolymer and of its complexes with lysozyme in aqueous solution. It is found that during the coil-to-globule transition of PNIPAM new bonds within the polymer aggregates are created, making the transition of the aggregates partially irreversible. This effect is also found for the protein loaded PEO-b-PNIPAM-b-PAA aggregates whereas in this case protein globules appear to enhance the formation of bonds, making the transition totally irreversible. The internal dynamics of both aggregates and complexes are “frozen” once the temperature is increased upon PINIPAM's LCST in water and remain so evenmore » when the temperature drops below LCST. As a result, we investigate the complexation kinetics of lysozyme and PEO-b-PNIPAM-b-PAA and observe that it occurs in two stages, one where protein globules adsorb on single pre-formed aggregates and one where protein globules cause inter-aggregate clustering.« less

  4. Kinetics of temperature response of PEO-b-PNIPAM-b-PAA triblock terpolymer aggregates and of their complexes with lysozyme

    SciTech Connect

    Papagiannopoulos, Aristeidis; Meristoudi, Anastasia; Hong, Kunlun; Pispas, Stergios

    2015-12-18

    We present the kinetics of temperature response of a PEO-b-PNIPAM-b-PAA triblock terpolymer and of its complexes with lysozyme in aqueous solution. It is found that during the coil-to-globule transition of PNIPAM new bonds within the polymer aggregates are created, making the transition of the aggregates partially irreversible. This effect is also found for the protein loaded PEO-b-PNIPAM-b-PAA aggregates whereas in this case protein globules appear to enhance the formation of bonds, making the transition totally irreversible. The internal dynamics of both aggregates and complexes are “frozen” once the temperature is increased upon PINIPAM's LCST in water and remain so even when the temperature drops below LCST. As a result, we investigate the complexation kinetics of lysozyme and PEO-b-PNIPAM-b-PAA and observe that it occurs in two stages, one where protein globules adsorb on single pre-formed aggregates and one where protein globules cause inter-aggregate clustering.

  5. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    PubMed Central

    van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erné, Ben H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  6. Short Stimulation of Electro-Responsive PAA/Fibrin Hydrogel Induces Collagen Production

    PubMed Central

    Rahimi, Nastaran; Swennen, Geertje; Verbruggen, Sanne; Scibiorek, Martyna; Molin, Daniel G.

    2014-01-01

    Acrylic acid/fibrin hydrogel can mechanically stimulate cells when an external electrical field is applied, enabling them to migrate and align throughout the depth of the gel. The ability of electro-responsive polyacrylic acid (PAA)/fibrin hydrogel to promote collagen production and remodeling has been investigated by three-dimensional (3D) culturing and conditioning of smooth muscle cells (SMCs). SMCs-seeded hydrogels were subjected to an alternating electrical field (0.06 V/mm) for 2 h for one, two, or three times per week during 4 weeks of culturing. Fluorescent images of collagen structure and accumulation, assessed by CNA-35 probe, showed increased collagen content (>100-fold at 1× stimulation/week) in the center of the hydrogels after 4 weeks of culture. The increase in collagen production correlated with increasing extracellular matrix gene expression and resulted in significantly improved mechanical properties of the stimulated hydrogels. Matrix metalloproteinase (MMP)-2 activity was also significantly enhanced by stimulation, which probably has a role in the reorganization of the collagen. Short stimulation (2 h) induced a favorable response in the cells and enhanced tissue formation and integrity of the scaffold by inducing collagen production. The presented set up could be used for conditioning and improving the functionality of current tissue-engineered vascular grafts. PMID:24341313

  7. Aqueous – Phase Synthesis of PAA in PVDF Membrane Pores for Nanoparticle Synthesis and Dichlorobiphenyl Degradation

    PubMed Central

    Smuleac, V.; Bachas, L.; Bhattacharyya, D.

    2009-01-01

    This paper deals with bimetallic (Fe/Pd) nanoparticle synthesis inside the membrane pores and application for catalytic dechlorination of toxic organic compounds form aqueous streams. Membranes have been used as platforms for nanoparticle synthesis in order to reduce the agglomeration, encountered in solution phase synthesis which leads to a dramatic loss of reactivity. The membrane support, polyvinylidene fluoride (PVDF) was modified by in situ polymerization of acrylic acid in aqueous phase. Subsequent steps included ion exchange with Fe2+, reduction to Fe0 with sodium borohydride and Pd deposition. Various techniques, such as STEM, EDX, FTIR and permeability measurements, were used for membrane characterization and showed that bimetallic (Fe/Pd) nanoparticles with an average size of 20-30 nm have been incorporated inside of the PAA-coated membrane pores. The Fe/Pd–modified membranes showed a high reactivity toward a model compound, 2, 2′-dichlorobyphenyl and a strong dependence of degradation on Pd (hydrogenation catalyst) content. The use of convective flow substantially reduces the degradation time: 43% conversion of dichlorobiphenyl to biphenyl can be achieved in less than 40 s residence time. Another important aspect is the ability to regenerate and reuse the Fe/Pd bimetallic systems by washing with a solution of sodium borohydride, because the iron becomes inactivated (corroded) as the dechlorination reaction proceeds. PMID:20161475

  8. Frequency-dependent magnetic susceptibility of magnetite and cobalt ferrite nanoparticles embedded in PAA hydrogel.

    PubMed

    van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  9. CS/PAA@TPGS/PLGA nanoparticles with intracellular pH-sensitive sequential release for delivering drug to the nucleus of MDR cells.

    PubMed

    Wang, Ying-Ying; Zhang, Dan-Dan; Kong, Yan-Yan; Shao, Luan-Luan; Zhang, Fen-Yi; Gao, Yu; Mu, Xu; Wang, Jie; Li, Hao-Fan; Yu, Shu-Qin; Xu, Qian

    2016-09-01

    Development of novel nano-drug delivery systems (NDDS) that can transport anticancer drugs into cell nuclei is still a highly desirable strategy for reversing multi-drug resistance (MDR) in cancer therapy. Herein, we designed and prepared a novel NDDS, designated S@L NPs, in which several smaller nanoparticles are contained within a larger nanoparticle. Our S@L NPs (CS/PAA/VP-16@TPGS/PLGA NPs) possess a structure in which smaller nanoparticles (Chitosan-Poly(acrylic acid) nanoparticles, CS/PAA NPs) containing the drug etoposide (VP-16) are loaded within a larger nanoparticle (Vitamin E d-a-tocopheryl polyethylene glycol 1000 succinate-modified poly(lactic-co-glycolic acid) nanoparticles, TPGS/PLGA NPs). The system utilizes intracellular pH gradients to achieve pH-sensitive sequential release within different intracellular domains of MDR cells. S@L NPs could be triggered to degrade and release CS/PAA/VP-16 NPs in the acid environment of the cytosol, endosomes or lysosomes, and CS/PAA/VP-16 NPs were capable of entering the nucleus through nucleopores. It is significant that CS/PAA/VP-16 NPs exhibit disaggregation in the alkaline environment of the nucleus and thereby release the contained anticancer drug. Further mechanistic studies showed that CS/PAA/VP-16 NPs escaped retention and degradation within lysosomes and protected the drug from P-glycoprotein-induced efflux. Simultaneously, S@L NPs enhanced the anticancer effect of the loaded drug by inducing autophagy and apoptosis of MDR cells. This novel NDDS may provide a promising platform for nuclear drug delivery for reversing MDR. PMID:27289313

  10. Dual stimuli-responsive coating designed through layer-by-layer assembly of PAA-b-PNIPAM block copolymers for the control of protein adsorption.

    PubMed

    Osypova, A; Magnin, D; Sibret, P; Aqil, A; Jérôme, C; Dupont-Gillain, C; Pradier, C-M; Demoustier-Champagne, S; Landoulsi, J

    2015-11-01

    In this paper, we describe the successful construction, characteristics and interaction with proteins of stimuli-responsive thin nanostructured films prepared by layer-by-layer (LbL) sequential assembly of PNIPAM-containing polyelectrolytes and PAH. PAA-b-PNIPAM block copolymers were synthesized in order to benefit from (i) the ionizable properties of PAA, to be involved in the LbL assembly, and (ii) the sensitivity of PNIPAM to temperature stimulus. The impact of parameters related to the structure and size of the macromolecules (their molecular weight and the relative degree of polymerization of PAA and PNIPAM), and the interaction with proteins under physico-chemical stimuli, such as pH and temperature, are carefully investigated. The incorporation of PAA-b-PNIPAM into multilayered films is shown to be successful whatever the block copolymer used, resulting in slightly thicker films than the corresponding (PAA/PAH)n film. Importantly, the protein adsorption studies demonstrate that it is possible to alter the adsorption behavior of proteins on (PAA-b-PNIPAM/PAH)n surfaces by varying the temperature and/or the pH of the medium, which seems to be intimately related to two key factors: (i) the ability of PNIPAM units to undergo conformational changes and (ii) the structural changes of the film made of weak polyelectrolytes. The simplicity of construction of these PNIPAM block copolymer-based LbL coatings on a large range of substrates, combined with their highly tunable features, make them ideal candidates to be employed for various biomedical applications requiring the control of protein adsorption. PMID:26338028

  11. Design of a novel crosslinked HEC-PAA porous hydrogel composite for dissolution rate and solubility enhancement of efavirenz.

    PubMed

    Mabrouk, M; Chejara, D R; Mulla, J A S; Badhe, R V; Choonara, Y E; Kumar, P; du Toit, L C; Pillay, V

    2015-07-25

    The purpose of this research was to synthesize, characterize and evaluate a Crosslinked Hydrogel Composite (CHC) as a new carrier for improving the solubility of the anti-HIV drug, efavirenz. The CHC was prepared by physical blending of hydroxyethylcellulose (HEC) with poly(acrylic acid) (PAA) (1:1) in the presence of poly(vinyl alcohol) (PVA) (as a crosslinker) (1:5) under lyophilization. Efavirenz was loaded in situ into the CHC in varying proportions (200-600 mg). The CHC demonstrated impressive rheological properties (dynamic viscosity=6053 mPa; 500 s(-1)) and tensile strength (2.5 mPa) compared with the native polymers (HEC and PAA). The physicochemical and thermal behavior also confirmed that the CHC was compatible with efavirenz. The incorporation of efavirenz in the CHC increased the surface area (4.4489-8.4948 m(2)/g) and pore volume (469.547-776.916Å) of the hydrogel system which was confirmed by SEM imagery and BET surface area measurements. The solubility of efavirenz was significantly enhanced (150 times) in a sustained release manner over 24h as affirmed by the in vitro drug release studies. The hydration medium provided by the CHC network played a pivotal role in improving the efavirenz solubility via increasing hydrogen bonding as proved by the zeta potential measurements (-18.0 to +0.10). The CHC may be a promising alternative as an oral formulation for the delivery of efavirenz with enhanced solubility. PMID:26047962

  12. Impacts of ENSO on the South American Summer Monsoon During 1997-1999

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Zhou, Jia-Yu; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Using the National Center for Environmental Prediction (NCEP) Reanalysis, and CPC Merged Analysis Product (CMAP) rainfall, we have compared and contrasted the anomalies of the South American Summer Monsoon (SASM) during two extreme years of 1997/98 (EI Nino) and 1998/99 (La Nina). The results are assessed against a "canonical" ENSO response (CER) pattern for the SASM obtained from empirical mode decomposition based on a previous period (1980-1995). Overall, the SASM anomalies compare well with CER, but with some important differences. Anomalies occurring in the warm phase of the 1997-98 El Nino are very significant and robust, while those occurring in 1998/99 La Nina, appear to be reversed from 1997/98, but are relatively weak and less well-defined. The most pronounced signal in DJF 1997/98 is the development of drought conditions in northern Brazil, excessive rainfall over northern Peru and Ecuador, and over Uruguay and southern Brazil. The tropical rainfall anomalies are associated with the eastward shift of the Walker circulation, which is represented by pronounced low-level anomalous westerlies over the equatorial eastern Pacific and easterlies over northern Brazil. The easterlies are deflected sharply southeastward by the steep topography of the Andes, enhancing the low-level jet (LLJ) along the eastern foothills of the Andes near 15-20 S. The LLJ penetrates deep into the extratropics, yielding rainfall anomalies further poleward compared to CER. During DJF 1997/98, the eastward expansion of the warm tropospheric temperature over the Nino-3 region causes anomalous geopotential height to develop in the upper troposphere above the Altiplano, leading to a strengthened Bolivian High. An upper-tropospheric jet anomaly maximum is found over the subtropical continent near 30 S, due to increasing meridional gradient of tropospheric temperature, as well as teleconnection patterns linking the South Pacific and the South Atlantic. Consistent with the CER, the South Pacific High is weakened, and the South Atlantic High is strengthened in DJF 1997/98. However, rather than appearing as a coherent large scale signal over the entire Atlantic as in CER, the South Atlantic High anomalies in DJF 1997/98 split into two separate high pressure centers; one located south of the Amazon basin, and another over the southeastern South Atlantic. The former is induced as a Rossby-wave response by ENSO-Induced sinking motion over nor-them and eastern Brazil, and the latter may be associated with extratropical teleconnection signals. Anomalous convection observed over equatorial western Africa may also have contributed to the different circulation response over the Atlantic in DFJ 1997/99 compared to the CER. Comparison of the evolution of the SASM anomalies in 1997-99 with their corresponding annual cycles, suggest that the anomalies are phase-locked to and represent either enhancement or reduction of the annual variations. Results suggest that, from a system perspective the SASM was strengthened during the 1997/98 El Nino and weakened, albeit to a lesser extent, during the 1998/99 La Nina.

  13. Daily birth numbers in Passo Fundo, South Brazil, 1997-1999: trends and periodicities.

    PubMed

    Mikulecky, M; Lisboa, H R K

    2002-08-01

    Between October 6, 1997 and April 30, 1999, 5011 births (mean: 8.76 per day) were registered in the city of Passo Fundo, South Brazil. The sequence of 572 daily birth numbers was not random (iteration test). Neyman distribution (m = yen ) showed the best fit. Clusters of days with higher birth numbers alternated with days with low numbers of births. Periodogram analysis revealed a significant periodicity of 6.98 days. The cosinor regression, testing 10 a priori supposed period lengths, found significant seasonality peaking in August-September and significantly highest birth numbers on Thursdays. Among the lunar and solar rotation cycles, the tropic lunar cycle and its 4th harmonic were most pronounced, in agreement with results concerning natality in Germany obtained by Svante Arrhenius in the 19th century. These findings confirm Derer-Halberg's concept of multiseptans. In addition to cycling, a significantly increasing linear trend with a daily increase of 0.0045 births was encountered. This documents a growth of the population in agreement with national statistical data. PMID:12185392

  14. National Science Foundation Support for Two-Year Colleges, Fiscal Years 1997-1999.

    ERIC Educational Resources Information Center

    National Science Foundation, Arlington, VA. Div. of Undergraduate Education.

    This National Science Foundation (NSF) report, prepared by NSF's Division of Undergraduate Education (DUE), analyzes the role the Foundation plays in recognizing and supporting the critical function of community colleges in science, mathematics, engineering, and technology (SMET) education. The Foundation aims to improve and strengthen SMET…

  15. Trends in positive drug tests, United States Air Force, fiscal years 1997-1999.

    PubMed

    Grayson, J Kevin; Gibson, Roger L; Shanklin, Shari L; Neuhauser, Katerina M; McGhee, Charles

    2004-07-01

    We investigated the relationship between various demographic factors and the risk of testing positive for marijuana or cocaine use in the U.S. Air Force in fiscal years 1997 through 1999. Overall test positive rates for marijuana and cocaine were very low, at 0.24 and 0.07% of all tests, respectively. However, monthly test positive rates increased significantly during the study period while the number of tests conducted decreased by more than 50%. Gender, race/ethnicity, service component, military rank, education level, and assignment location each predicted the likelihood of testing positive for marijuana or cocaine use. These findings were consistent with annual surveys of self-reported drug use conducted in military and civilian populations in the United States. We conclude that overall testing percentages should be re-evaluated in light of these findings, but we do not recommend oversampling from population subgroups that demonstrated a higher likelihood of testing positive. PMID:15291178

  16. Molecular epidemiology studies on occupational and environmental exposure to mutagens and carcinogens, 1997-1999.

    PubMed Central

    Srám, R J; Binková, B

    2000-01-01

    Molecular epidemiology is a new and evolving area of research, combining laboratory measurement of internal dose, biologically effective dose, biologic effects, and influence of individual susceptibility with epidemiologic methodologies. Biomarkers evaluated were selected according to basic scheme: biomarkers of exposure--metabolites in urine, DNA adducts, protein adducts, and Comet assay parameters; biomarkers of effect--chromosomal aberrations, sister chromatid exchanges, micronuclei, mutations in the hypoxanthine-guanine phosphoribosyltransferase gene, and the activation of oncogenes coding for p53 or p21 proteins as measured on protein levels; biomarkers of susceptibility--genetic polymorphisms of genes CYP1A1, GSTM1, GSTT1, NAT2. DNA adducts measured by 32P-postlabeling are the biomarker of choice for the evaluation of exposure to polycyclic aromatic hydrocarbons. Protein adducts are useful as a biomarker for exposure to tobacco smoke (4-aminobiphenyl) or to smaller molecules such as acrylonitrile or 1,3-butadiene. Of the biomarkers of effect, the most common are cytogenetic end points. Epidemiologic studies support the use of chromosomal breakage as a relevant biomarker of cancer risk. The use of the Comet assay and methods analyzing oxidative DNA damage needs reliable validation for human biomonitoring. Until now there have not been sufficient data to interpret the relationship between genotypes, biomarkers of exposure, and biomarkers of effect for assessing the risk of human exposure to mutagens and carcinogens. PMID:10698723

  17. Higher Education Trends (1997-1999): Graduate and Professional Education. ERIC-HE Trends.

    ERIC Educational Resources Information Center

    Kezar, Adrianna J.

    The literature on graduate and professional education reflects many of the trends present in the literature on undergraduate education, including concerns about student learning; transforming the curriculum to be more inclusive; internationalization of the curriculum; incorporation of technology; growth in interdisciplinary education; and outcomes…

  18. A comparison of eastern and western Hong Kong phytoplankton from weekly samples (1997-1999)

    NASA Astrophysics Data System (ADS)

    Dickman, Mike; Sen-Ming, Tang; Lai, Jessie

    2002-03-01

    Weekly phytoplankton samples were taken from western Hong Kong (Lamma) from Jan. 1997 to Dec. 1999 and from Port Shelter in Eastern Hong Kong from January 1998 to December 1999. During that time diatom blooms occurred repeatedly at both sites but never in synchrony. One species would bloom at one site and then weeks later it or another species would bloom at the other site; while the 1998 red tide of the mucus producing dinoflagellate Gymnodinium mikimotoi occurred at both sites. It first occurred at the Port Shelter site in March and did not appear at the Lamma site until April. With the single exception of this species, no other dinoflagellate reached bloom concentrations at the Lamma site. In addition, dinoflagellate abundance at the Lamma site was significantly lower (P<0.05) than that at the Port Shelter site. This was correlated with a significantly higher turbidity (i. e. low Secchi transparency) and higher turbulence (stronger currents) at the Lamma site. Annual variation in surface temperature correlated with total surface phytoplankton abundance at both our sample sites. Phytoplankton abundance increased in spring as water temperatures warmed. In fall, as surface water temperatures began to decline and the monsoon rains became less frequent there was a reduction in phytoplankton abundance associated with the reduction in temperature and light. Because so many variables co-occur with temperature (e. g. the amount of rainfall light intensity and light duration etc.) it is not possible to cite temperature as the causal factor associated weth controlling phytoplankton abundance at our two sample sites. Our data support the rather controversial notion that percentage-wise, there are relatively more harmful bloom forming species in nutrient-rich coastal waters than there are in the world's oceans. 16% of the dinoflagellate species and 10.3% of the diatom species observed at our two sample sites were classed as harmful. These percentages were higher than those cited by Sournia (1995) for the worlds oceans (9.6% and 6.8% respectively). This raises the possibility that there are relatively more toxic species in the nutrient-rich coastal waters of the world than there are in the mid ocean nutrient-poor areas of the world. Some reasons for this are briefly discussed.

  19. Evaluation of Juvenile Fall Chinook Stranding on the Hanford Reach, 1997-1999 Interim Report.

    SciTech Connect

    Wagner, Paul; Nugent, John; Price, William

    1999-02-15

    Pilot work conducted in 1997 to aid the development of the study for the 1998 Evaluation of Juvenile Fall Chinook Stranding on The Hanford Reach. The objectives of the 1997 work were to: (1) identify juvenile chinook production and rearing areas..., (2) identify sampling sites and develop the statistical parameters necessary to complete the study, (3) develop a study plan..., (4) conduct field sampling activities...

  20. Directory of International and Area Studies Librarians in Ohio, 1997-1999.

    ERIC Educational Resources Information Center

    Case, Beau David, Comp.; Riedinger, Edward A., Comp.

    This work published every 2 years is a directory of international and area studies librarians in Ohio. It is the first project of the Organization of International and Area Studies Librarians in Ohio (OIALO) organized in July 1996. This directory identifies 35 individuals with experience in collection development, reference service, and cataloging…

  1. News on Children and Violence on the Screen, 1997-1999.

    ERIC Educational Resources Information Center

    von Feilitzen, Cecilia, Ed.

    1999-01-01

    This document is comprised of the 1997 through 1999 newsletters of the UNESCO International Clearinghouse on Children and Violence on the Screen, published three times a year. It provides topical information on research findings concerning children and media violence, children's media use, and activities aiming to limit gratuitous media violence.…

  2. Higher Education Trends (1997-1999): Finance. ERIC-HE Trends.

    ERIC Educational Resources Information Center

    Kezar, Adrianna J.

    The literature on financial issues in higher education is limited. Six major themes in the literature in l996 include the reduced federal role and increased state role in funding; managing costs, including deferred maintenance and capital spending in times of shrinking resources; concern about rising tuition and its impact on access; concern about…

  3. Epidemiological surveillance of ovine hydatidosis in Tierra del Fuego, Patagonia Argentina, 1997-1999.

    PubMed

    Zanini, Fabián; Gonzalo, Roberto; Pérez, Héctor; Aparici, Inés; Soto, Ximena; Guerrero, Juvenal; Cerrone, Gloria; Elissondo, Celina

    2006-06-15

    Cystic echinococcosis is the most prevalent zoonosis in Tierra del Fuego province, Argentina, with important economic, productive and public health consequences. The present work was performed to determine the ovine prevalence in Tierra del Fuego, Argentina, as well as to evaluate the quality of diagnostic systems in slaughterhouses. Moreover, genetic analyses to characterize the strain of Echinococcus granulosus involved in the region were done. The first actions to perform a diagnosis of the epidemiological situation of hydatidosis in Tierra del Fuego were done between 1976 and 1977. A canine prevalence of 80% and an ovine prevalence of 55% results were obtained. Since 1979 the control program of Hydatidosis of Tierra del Fuego was implemented. It was based on semiannual canine anthelmintic treatment with praziquantel at dose of 5mg/kg, and complemented with sanitary education and canine and ovine epidemiological surveillance. During May 1997-January 1999: 5,916 sheep coming from 20 farms of the programmatic area were evaluated. In the lamb category, hydatid cysts were not found. In the adults category, 62 infected animals were found (3.2%). The ovine prevalence was 1.1% and there was 100% of coincidence between diagnosis in the slaughterhouse, re-inspection in the laboratory and histopathological study. The marked decrease in the prevalence observed for sheep infection evidenced a destabilization of the biological cycle of the parasite. This could be explained by the application of a control program with uninterrupted systematic actions. Polymerase chain reaction-ribosomal ITS-1 DNA (rDNA) restriction fragment length polymorphism (PCR-RFLP) analysis and partial sequencing of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene were used to characterize E. granulosus isolates collected from different regions of Tierra del Fuego to determine which genotypes occurred in this region. The results revealed the presence of the G1 genotype (sheep-dog strain). This is the first time that a molecular analysis was performed for the E. granulosus isolates from Tierra del Fuego. PMID:16504405

  4. Higher Education Trends (1997-1999): Program Evaluation. ERIC-HE Trends.

    ERIC Educational Resources Information Center

    Kezar, Adrianna J.

    The amount of literature on program evaluation decreased in 1996, continuing a trend begun in the late 1980s. One exception to this is the literature on assessment. Another frequent issue is the technique of evaluation. Many examples of research on evaluation are from international settings, where accountability and evaluation appear to be…

  5. METAZOOPLANKTON DYNAMICS IN THE SALTON SEA, CALIFORNIA, 1997-1999. (R826552)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  6. THERMAL, MIXING, AND OXYGEN REGIMES OF THE SALTON SEA, CALIFORNIA, 1997-1999. (R826552)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. Higher Education Trends (1997-1999): Curriculum. ERIC-HE Trends.

    ERIC Educational Resources Information Center

    Kezar, Adrianna J.

    Literature on college curriculum has been declining since the early 1990s, representing under 5 percent of the literature added to the ERIC database in 1996. One reason seems to be the emphasis on instruction; another is that information on curricular movements are often addressed in the literature on instructional change. Trends in 1996 in the…

  8. Crystallization and preliminary X-ray analysis of two variants of the Escherichia coli O157 ParE2–PaaA2 toxin–antitoxin complex

    PubMed Central

    Sterckx, Yann G. J.; Haesaerts, Sarah; Van Melderen, Laurence; Loris, Remy

    2014-01-01

    The paaR2–paaA2–parE2 operon is a three-component toxin–antitoxin module encoded in the genome of the human pathogen Escherichia coli O157. The toxin (ParE2) and antitoxin (PaaA2) interact to form a nontoxic toxin–antitoxin complex. In this paper, the crystallization and preliminary characterization of two variants of the ParE2–PaaA2 toxin–antitoxin complex are described. Selenomethionine-derivative crystals of the full-length ParE2–PaaA2 toxin–antitoxin complex diffracted to 2.8 Å resolution and belonged to space group P41212 (or P43212), with unit-cell parameters a = b = 90.5, c = 412.3 Å. It was previously reported that the full-length ParE2–PaaA2 toxin–antitoxin complex forms a higher-order oligomer. In contrast, ParE2 and PaaA213–63, a truncated form of PaaA2 in which the first 12 N-terminal residues of the antitoxin have been deleted, form a heterodimer as shown by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. Crystals of the PaaA213–63–ParE2 complex diffracted to 2.7 Å resolution and belonged to space group P6122 (or P6522), with unit-cell parameters a = b = 91.6, c = 185.6 Å. PMID:25195911

  9. Small-angle X-ray scattering- and nuclear magnetic resonance-derived conformational ensemble of the highly flexible antitoxin PaaA2.

    PubMed

    Sterckx, Yann G J; Volkov, Alexander N; Vranken, Wim F; Kragelj, Jaka; Jensen, Malene Ringkjøbing; Buts, Lieven; Garcia-Pino, Abel; Jové, Thomas; Van Melderen, Laurence; Blackledge, Martin; van Nuland, Nico A J; Loris, Remy

    2014-06-10

    Antitoxins from prokaryotic type II toxin-antitoxin modules are characterized by a high degree of intrinsic disorder. The description of such highly flexible proteins is challenging because they cannot be represented by a single structure. Here, we present a combination of SAXS and NMR data to describe the conformational ensemble of the PaaA2 antitoxin from the human pathogen E. coli O157. The method encompasses the use of SAXS data to filter ensembles out of a pool of conformers generated by a custom NMR structure calculation protocol and the subsequent refinement by a block jackknife procedure. The final ensemble obtained through the method is validated by an established residual dipolar coupling analysis. We show that the conformational ensemble of PaaA2 is highly compact and that the protein exists in solution as two preformed helices, connected by a flexible linker, that probably act as molecular recognition elements for toxin inhibition. PMID:24768114

  10. Study of the interaction between a diblock polyelectrolyte PDMA-b-PAA and a gemini surfactant 12-6-12 in basic media.

    PubMed

    Kang, Hongmei; Peng, Baoliang; Liang, Yanyan; Han, Xia; Liu, Honglai

    2009-05-01

    The interactions between negatively charged diblock polyelectrolyte PDMA(71)-b-PAA(59) and oppositely charged gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) in basic media were studied using dynamic light scattering, fluorescence spectroscopy, surface tension, and (1)H NMR. With increased addition of surfactant, the conformation of polyelectrolyte experienced changes from the initial unimer with open-extended PAA block, to the nano-scaled aggregates/complexes with a maximum hydrodynamic diameter (D(h)), and finally to the stable complexes with a smaller D(h). Accordingly, the value of D(h) during the whole process of increasing the surfactant concentration changed from 14-17 nm, to 184 nm, and to the final 70 nm, respectively. This transformation was driven by the electrostatic attractive/repulsive interactions, the hydrophobic interaction between hydrophobic surfactant tails, and the hydrophilicity of PDMA block. PMID:19217121

  11. A unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex.

    PubMed

    Sterckx, Yann G-J; Jové, Thomas; Shkumatov, Alexander V; Garcia-Pino, Abel; Geerts, Lieselotte; De Kerpel, Maia; Lah, Jurij; De Greve, Henri; Van Melderen, Laurence; Loris, Remy

    2016-04-24

    Many bacterial pathogens modulate their metabolic activity, virulence and pathogenicity through so-called "toxin-antitoxin" (TA) modules. The genome of the human pathogen Escherichia coli O157 contains two three-component TA modules related to the known parDE module. Here, we show that the toxin EcParE2 maps in a branch of the RelE/ParE toxin superfamily that is distinct from the branches that contain verified gyrase and ribosome inhibitors. The structure of EcParE2 closely resembles that of Caulobacter crescentus ParE but shows a distinct pattern of conserved surface residues, in agreement with its apparent inability to interact with GyrA. The antitoxin EcPaaA2 is characterized by two α-helices (H1 and H2) that serve as molecular recognition elements to wrap itself around EcParE2. Both EcPaaA2 H1 and H2 are required to sustain a high-affinity interaction with EcParE2 and for the inhibition of EcParE2-mediated killing in vivo. Furthermore, evidence demonstrates that EcPaaA2 H2, but not H1, determines specificity for EcParE2. The initially formed EcPaaA2-EcParE2 heterodimer then assembles into a hetero-hexadecamer, which is stable in solution and is formed in a highly cooperative manner. Together these findings provide novel data on quaternary structure, TA interactions and activity of a hitherto poorly characterized family of TA modules. PMID:26996937

  12. Expression, purification, crystallization and preliminary X-ray analysis of the PaaI-like thioesterase SAV0944 from Staphylococcus aureus.

    PubMed

    Khandokar, Yogesh B; Roman, Noelia; Smith, Kate M; Srivastava, Parul; Forwood, Jade K

    2014-02-01

    Staphylococcus aureus is the causative agent of many diseases, including meningitis, bacteraemia, pneumonia, food poisoning and toxic shock syndrome. Structural characterization of the PaaI-like thioesterase SAV0944 (SaPaaI) from S. aureus subsp. aureus Mu50 will aid in understanding its potential as a new therapeutic target by knowledge of its molecular details and cellular functions. Here, the recombinant expression, purification and crystallization of SaPaaI thioesterase from S. aureus are reported. This protein initially crystallized with the ligand coenzyme A using the hanging-drop vapour-diffusion technique with condition No. 40 of Crystal Screen from Hampton Research at 296 K. Optimal final conditions consisting of 24% PEG 4000, 100 mM sodium citrate pH 6.5, 12% 2-propanol gave single diffraction-quality crystals. These crystals diffracted to beyond 2 Å resolution at the Australian Synchrotron and belonged to space group P12(1)1, with unit-cell parameters a = 44.05, b = 89.05, c = 60.74 Å, β = 100.5°. Initial structure determination and refinement gave an R factor and R(free) of 17.3 and 22.0%, respectively, confirming a positive solution in obtaining phases using molecular replacement. PMID:24637766

  13. RF beam transmission of x-band PAA system utilizing large-area, polymer-based true-time-delay module developed using imprinting and inkjet printing

    NASA Astrophysics Data System (ADS)

    Pan, Zeyu; Subbaraman, Harish; Zhang, Cheng; Li, Qiaochu; Xu, Xiaochuan; Chen, Xiangning; Zhang, Xingyu; Zou, Yi; Panday, Ashwin; Guo, L. Jay; Chen, Ray T.

    2016-02-01

    Phased-array antenna (PAA) technology plays a significant role in modern day radar and communication networks. Truetime- delay (TTD) enabled beam steering networks provide several advantages over their electronic counterparts, including squint-free beam steering, low RF loss, immunity to electromagnetic interference (EMI), and large bandwidth control of PAAs. Chip-scale and integrated TTD modules promise a miniaturized, light-weight system; however, the modules are still rigid and they require complex packaging solutions. Moreover, the total achievable time delay is still restricted by the wafer size. In this work, we propose a light-weight and large-area, true-time-delay beamforming network that can be fabricated on light-weight and flexible/rigid surfaces utilizing low-cost "printing" techniques. In order to prove the feasibility of the approach, a 2-bit thermo-optic polymer TTD network is developed using a combination of imprinting and ink-jet printing. RF beam steering of a 1×4 X-band PAA up to 60° is demonstrated. The development of such active components on large area, light-weight, and low-cost substrates promises significant improvement in size, weight, and power (SWaP) requirements over the state-of-the-art.

  14. The characterization of EIAV reverse transcriptase and its inhibition by 5'-triphosphates of 2'-deoxyuridine analogs, PFA and PAA.

    PubMed

    Tao, P; Zhang, X; Quan, K

    1990-01-01

    A characterization of equine infectious anemia virus reverse transcriptase (EIAV RT) and its inhibition by 5'-triphosphate analogs was undertaken to explore the possibility of using EIAV RT as an in vitro model for studying human immunodeficiency virus (HIV). EIAV RT activity was found to be dependent on the bivalent cations Mg++ and Mn++. The optimal pH for enzyme reaction was pH 8.2. EIAV RT preferred a 70 mmol/L concentration of monovalent salts. Phosphonoformic acid (PFA) was an active inhibitor of EIAV RT, but phosphonoacetic acid (PAA) and N-ethylmaleimide (NEM) were not. The inhibition of EIAV RT activity by 5'-triphosphates of nucleoside derivatives was in the following decreasing order: FLTTP greater than AZTTP greater than nPrearaUTP greater than nPredUTP = CEdUTP greater than EtdUTP greater than nPrdUTP greater than HMdUTP. nPrearaUTP was a linear competitive and PFA a linear noncompetitive inhibitor of EIAV RT with respect to dTTP. Apparent Kis and Kii were 1.5 and 2.2 mumol/L respectively. The susceptibility pattern of EIAV RT to inhibitors was similar to that of HIV RT. PMID:1711694

  15. Controllable Cooperative Self-Assembly of PS-b-PAA/PS-b-P4VP Mixture by Tuning the Intercorona Interaction.

    PubMed

    Geng, Zhen; Cheng, Zhongkai; Zhu, Yutian; Jiang, Wei

    2016-06-23

    The cooperative self-assembly of amphiphilic polystyrene-block-poly(acrylic acid) (PS144-b-PAA22) and polystyrene-block-poly(4-vinylpyridine) (PS144-b-P4VP33) diblock copolymers in DMF/H2O mixtures has been investigated. Both copolymers self-assemble into small spherical micelles (SSMs) if used individually. However, the equimolar mixture of these two copolymers cooperatively self-assembles into vesicles. It is found that the formation of vesicles is attributed to the complex interactions between PAA and P4VP chains, including the hydrogen bonds between un-ionized acrylic acid units and pyridine units as well as the electronic attractions between ionized acrylic acid units and protonated pyridine units. Since these interactions between PAA and P4VP chains depend on pH value, the cooperatively self-assembled morphology can be easily tuned by the addition of HCl or NaOH. At high addition of H(+) or OH(-), the intercorona interaction is repulsive and the copolymer mixture tends to form SSMs (basic condition) or cylindrical micelles (acidic condition), whereas it prefers to aggregate into vesicles at low addition of H(+) or OH(-) because the intercorona interaction is attractive. Interestingly, the same morphology of the self-assembled aggregates can be obtained either at high H(+) addition or at low OH(-) addition, which results from the nonmonotonic variation of the intercorona interaction along with the addition of HCl or NaOH. The current study implies that it is the intercorona interaction rather than the chemical condition that dominates the cooperatively self-assembled morphology. PMID:27195581

  16. Report from PAA.

    PubMed

    1995-06-01

    The Population Association of America Annual Meeting, held in San Francisco April 6-8, 1995, generated papers on the key demographic themes of marriage, birth, mortality, and migration. In the US 47% of people between the ages of 25 and 44 have lived with an unmarried partner for some period, up from 37% during 1987-1988. For teenagers, absence of contact with fathers is associated with symptoms of depression, becoming a teen parent, and delinquency. Single fathers in 1990 were younger and had lower incomes than in the past. About 40% of nonpaying fathers had children out of wedlock; 30% to 48% had low or no income. The tendency of Whites to leave or avoid minority neighborhoods is due to perceptions about crime, quality of the schools, neighborhood deterioration, and the socioeconomic level of neighbors. Although African-American death rates generally are higher than those of Whites, the pattern seems to reverse itself after age 85. Surprisingly, survival probability at ages 80-95 for US Whites is higher than that in Europe and Japan. When immigrants enter an area, there is not much evidence of low-skilled native-born people moving out. Families with undocumented heads received an average of $6,080 in welfare benefits, while refugees received $10,444. The Social Security system is shifting large amounts of money from regions of the country with younger age structures, such as California, to states with older age structures, such as Florida. Among other topics, the remarkably low total fertility rate of 3.4 in the Bangladesh 1993-1994 Demographic and Health Survey was questioned as biased; the infant mortality data for Tajikistan appeared to be suspect; the diffusion of information about family planning in Africa was mentioned; the significance of the 1994 International Conference on Population and Development regarding reproductive health services was hailed; and USAID's designing of indicators in safe pregnancy, breastfeeding, and women's nutrition was related. PMID:12289924

  17. Crystallization and preliminary X-ray diffraction studies of the transcriptional repressor PaaX, the main regulator of the phenylacetic acid degradation pathway in Escherichia coli W

    PubMed Central

    Rojas-Altuve, Alzoray; Carrasco-López, César; Hernández-Rocamora, Víctor M.; Sanz, Jesús M.; Hermoso, Juan A.

    2011-01-01

    PaaX is the main regulator of the phenylacetic acid aerobic degradation pathway in bacteria and acts as a transcriptional repressor in the absence of its inducer phenylacetyl-coenzyme A. The natural presence and the recent accumulation of a variety of highly toxic aromatic compounds owing to human pollution has created considerable interest in the study of degradation pathways in bacteria, the most important microorganisms capable of recycling these compounds, in order to design and apply novel bioremediation strategies. PaaX from Escherichia coli W was cloned, overexpressed, purified and crystallized using the sitting-drop vapour-diffusion method at 291 K. Crystals grew from a mixture of 0.9 M Li2SO4 and 0.5 M sodium citrate pH 5.8. These crystals, which belonged to the monoclinic space group C2 with unit-cell parameters a = 167.88, b = 106.23, c = 85.87 Å, β = 108.33°, allowed the collection of an X-ray data set to 2.3 Å resolution. PMID:22102047

  18. EMERGENCE OF A MULTIDRUG-RESISTANT STRAIN OF SALMONELLA SEROTYPE NEWPORT IN THE UNITED STATES, NARMS 1997-1999

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the National Microbial Resistance Monitoring System (NARMS) for Enteric Bacteria participating state and local health departments send every tenth human Salmonella submitted to their laboratory to CDC. Also, the USDA tests chilled carcasses and other raw meat and poultry products, including grou...

  19. An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Republican River Basin: 1997-1999

    USGS Publications Warehouse

    May, T.W.; Walther, M.J.; Petty, J.D.; Fairchild, J.F.; Lucero, J.; Delvaux, M.; Manring, J.; Armbruster, M.; Hartman, D.

    2001-01-01

    The Republican River Basin of Colorado, Nebraska, and Kansas lies in a valley which contains Pierre Shale as part of its geological substrata. Selenium is an indigenous constituent in the shale and is readily leached into surrounding groundwater. The Basin is heavily irrigated through the pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water, sediment, benthic invertebrates, and/or fish were collected from 46 sites in the Basin and were analyzed for selenium to determine the potential for food-chain bioaccumulation, dietary toxicity, and reproductive effects of selenium in biota. Resulting selenium concentrations were compared to published guidelines or biological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 ??g L-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3-5 ??g L-1, constituting a moderate hazard. Selenium concentrations in sediment indicated little to no hazard for selenium accumulation from sediments into the benthic food chain. Ninety-five percent of benthic invertebrates collected exhibited selenium concentrations exceeding 3 ??g g-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 ??g g-1 selenium, indicating a high potential for toxicity and reproductive effects. However, examination of weight profiles of various species of collected individual fish suggested successful recruitment in spite of selenium concentrations that exceeded published biological effects thresholds for health and reproductive success. This finding suggested that universal application of published guidelines for selenium may be inappropriate or at least may need refinement for systems similar to the Republican River Basin. Additional research is needed to determine the true impact of selenium on fish and wildlife resources in the Basin.

  20. Development of potentiometric urea biosensor based on urease immobilized in PVA-PAA composite matrix for estimation of blood urea nitrogen (BUN).

    PubMed

    Jha, Sandeep Kumar; Topkar, Anita; D'Souza, Stanislaus F

    2008-04-24

    A urea biosensor was developed using the urease entrapped in polyvinyl alcohol (PVA) and polyacrylamide (PAA) composite polymer membrane. The membrane was prepared on the cheesecloth support by gamma-irradiation induced free radical polymerization. The performance of the biosensor was monitored using a flow-through cell, where the membrane was kept in conjugation with the ammonia selective electrode and urea was added as substrate in phosphate buffer medium. The ammonia produced as a result of enzymatic reaction was monitored potentiometrically. The potential of the system was amplified using an electronic circuit incorporating operational amplifiers. Automated data acquisition was carried by connecting the output to a 12-bit analog to digital converter card. The sensor working range was 1-1000 mM urea with a response time of 120 s. The enzyme membranes could be reused 8 times with more than 90% accuracy. The biosensor was tested for blood urea nitrogen (BUN) estimation in clinical serum samples. The biosensor showed good correlation with commercial Infinitytrade mark BUN reagent method using a clinical chemistry autoanalyzer. The membranes could be preserved in phosphate buffer containing dithiothreitol, beta-mercaptoethanol and glycerol for a period of two months without significant loss of enzyme activity. PMID:18329719

  1. Synthesis of TiO{sub 2} nanoparticles by self-assembling reverse micelle cores of PS-b-PAA for functional textile applications

    SciTech Connect

    Akpolat, Leyla Budama; Çakır, Burçin Acar; Topel, Önder Hoda, Numan

    2015-04-15

    Highlights: • TiO{sub 2} nanoparticles were synthesized within poly(styrene)-b-poly(acrylic acid) micelles. • The copolymer solution including nano TiO{sub 2} was coated onto textile fabrics. • UV-protective factor of nano TiO{sub 2} coated fabrics was estimated as 50+. • Nano TiO{sub 2} coated fabrics was found to exhibit a high photocatalytic activity. - Abstract: Titanium dioxide (i.e., titanium(IV) oxide, TiO{sub 2}) nanoparticles have been fabricated using a copolymer templating technique in micellar solution of poly(styrene)-block-poly(acrylic acid), PS(10912)-b-PAA(4842) synthesized by atom transfer radical polymerization (ATRP). The size and morphology of the synthesized TiO{sub 2} nanoparticles have been characterized via TEM and XRD measurements. The average size of TiO{sub 2} nanoparticles was determined as 13 ± 3 and 13 ± 4 nm for titanium:copolymer ratios of 20:1 and 33:1, respectively. The copolymer solution including nano TiO{sub 2} particles has been coated onto textile fabrics to enhance their UV-blocking and self-cleaning properties. It has been determined that nano TiO{sub 2} coated textile fabrics have very good UV-blocking properties with 50+ of the ultraviolet protecting factor (UPF) and high photocatalytic efficiency with 69.2% of the photodegradation of methylene blue.

  2. Managing Electronic Serials: Essays Based on the ALCTS Electronic Serials Institutes 1997-1999. ALCTS Papers on Library Technical Services & Collections, No. 9.

    ERIC Educational Resources Information Center

    Bluh, Pamela M., Ed.

    If managed well, electronic journals (e-journals) can be extremely efficient, saving money and space while improving access and speeding information delivery. With the help of the Internet, e-journals can also make library collections more accessible to both users and staff. Covering the process of managing electronic serials from licensing,…

  3. Snapshots of America's Families II: A View of the Nation and 13 States from the National Survey of America's Families, 1997-1999.

    ERIC Educational Resources Information Center

    Koppelman, Jane, Ed.

    This collection of snapshots examines the well-being of America's children and adults through the lens of the 1999 National Survey of America's Families. Snapshots include: "Foreword: Snapshots of America's Families II: A View of the Nation and 13 States from the National Survey of America's Families" (Alyssa Wigton and Alan Weil); "Family…

  4. The analysis of the structure of suicidal behaviours in the region of the Lublin voivodship in the years 1997-1999.

    PubMed

    Rudnicka-Drozak, Ewa; Skórzyńska, Hanna; Makara-Studzińska, Marta

    2002-01-01

    Suicide is a phenomenon that raises particularly strong emotions of the public creating a question about the sense of life and death. The phenomenon reflects customs, personal and social approach, as well as it undergoes historical and cultural changes. The aim of the study is to find the factors that influence making the decision about suicide. The analysis was concerned with the statistical data taken from the Voivodship Police Headquarters in Lublin and with death certificates in the Lublin voivodship. The highest suicide rates were for people included in the age group between 31 and 50. The suicides more frequently were males. PMID:12898825

  5. Lake Roosevelt Fisheries Evaluation Program; Assessment of the Lake Roosevelt Walleye Population: Compilation of 1997-1999 Data, 1999-2000 Annual Report.

    SciTech Connect

    McLellan, Jason; McLellan, Holly; Scholz, Allan

    2002-03-01

    A walleye mark-recapture study was conducted on Lake Roosevelt between 1997 and 1999. The primary objective of the study was to describe the status and biological characteristics of the walleye population in Lake Roosevelt by determining its abundance, movement patterns, age structure, growth, condition, and mortality. The abundance estimates were also to be used to estimate the consumptive impact of walleye on stocked kokanee and rainbow trout. Walleye were collected by electrofishing and angling. Each walleye was tagged with an individually numbered Floy tag. The Jolly-Seber model was used to estimate the size of the walleye population in 1999, using each year of the study as a mark-recapture occasion. Mark-recapture data collected in 1998 was re-analyzed in 1999 with the data pooled in various combinations, using closed and open population models, in an attempt to provide an estimate of walleye abundance that was unbiased, accurate, and more precise. Minimum distances traveled between mark and recapture location by tagged walleye were determined from tag returns. Over the three study years, a total of 12,343 walleye {ge} 150 mm TL were collected by Eastern Washington University (EWU), Spokane Tribe of Indians, and Washington Department of Fish and Wildlife, and of those, 10,770 were tagged and released. Of the 10,770 walleye marked and released, 775 were recaptured and returned to EWU. The 1999 abundance estimate ({+-} standard error) for walleye {ge} 150 mm TL was 129,183 ({+-} 45,578) and the estimated abundance ({+-} standard error) of walleye {ge} 200 mm TL was 101,508 ({+-} 35,603). A total of 38 population estimates were calculated for 1998. The estimates of the abundance of walleye {ge} 150 mm TL in Lake Roosevelt ranged from 84,335 to 180,568 fish. Estimates of the size of the walleye population {ge} 200 mm TL ranged from 14,971 to 173,702. The 1999 estimate, which used each study year as a mark-recapture occasion, was biased due to unequal capture probabilities. If biases were eliminated, the annual sampling strategy may be the most cost-effective. Of the reanalyzed 1998 estimates, the Schnabel corrected for tag loss and recruitment and the Jolly-Seber estimate, both calculated with the 200 mm minimum length, were recommended for modeling walleye consumption. Minimum distances traveled between mark and recapture location by tagged walleye marked on the spawning run ranged from 0 to 245 km over a range of 11 to 486 days. Minimum distances traveled between mark and recapture location by tagged walleye marked during the summer/fall ranged from 0 to 217 km over a range of 8 to 788 days. Walleye exhibited seasonal movement trends that included a migration to the spawning area in the upper Spokane River Arm in the spring, with peak spawning occurring in April and May, and a migration following spawning to summer habitats. Once at the summer habitat, walleye appeared to establish summer home ranges (SHR). Walleye collected in Lake Roosevelt in 1999 ranged in age from 0 to 8. Mean instantaneous and mean annual mortality were estimated at 0.62% and 46%. Mean condition factor (K{sub TL}) of the 343 walleye measured and weighed in 1999 was 0.83 (SD = 0.13). Walleye mortality rates appeared to be relatively stable. Mortality and growth were average when compared to other walleye producing waters. Walleye condition was low when compared to condition factors in 1980-83, 1988, 1989, and 1990. The K{sub TL}'s of walleye from Lake Roosevelt were slightly below average when compared to other walleye populations.

  6. Caliciviruses in hospitalized children, São Luís, Maranhão, 1997-1999: detection of norovirus GII.12.

    PubMed

    Portal, Thayara Morais; Siqueira, Jones Anderson Monteiro; Costa, Larissa Cristina Prado das Neves; Lima, Ian Carlos Gomes de; Lucena, Maria Silvia Sousa de; Bandeira, Renato da Silva; Linhares, Alexandre da Costa; Luz, Claudia Regina Nunes Eloi da; Gabbay, Yvone Benchimol; Resque, Hugo Reis

    2016-01-01

    Gastroenteritis is one of the most common diseases during childhood, with norovirus (NoV) and sapovirus (SaV) being two of its main causes. This study reports for the first time the incidence of these viruses in hospitalized children with and without gastroenteritis in São Luís, Maranhão. A total of 136 fecal samples were tested by enzyme immunoassays (EIA) for the detection of NoV and by reverse transcription-polymerase chain reaction (RT-PCR) for detection of both NoV and SaV. Positive samples for both agents were subjected to sequencing. The overall frequency of NoV as detected by EIA and RT-PCR was 17.6% (24/136) and 32.6% (15/46), respectively in diarrheic patients and 10.0% (9/90) in non-diarrheic patients (p<0.01). Of the diarrheic patients, 17% had fever, vomiting and anorexia, and 13% developed fever, vomiting and abdominal pain. Of the 24 NoV-positive samples, 50% (12/24) were sequenced and classified as genotypes GII.3 (n=1), GII.4 (6), GII.5 (1), GII.7 (2), GII.12 (1) and GII.16 (1). SaV frequency was 9.8% (11/112), with 22.6% (7/31) in diarrheic patients and 4.9% (4/81) in nondiarrheic (p=0.04) ones. In diarrheic cases, 27.3% had fever, vomiting and anorexia, whereas 18.2% had fever, anorexia and abdominal pain. One SaV-positive sample was sequenced and classified as GII.1. These results show a high genetic diversity of NoV and higher prevalence of NoV compared to SaV. Our data highlight the importance of NoV and SaV as enteropathogens in São Luís, Maranhão. PMID:27161199

  7. SPIO nanoparticle-stabilized PAA-F127 thermosensitive nanobubbles with MR/US dual-modality imaging and HIFU-triggered drug release for magnetically guided in vivo tumor therapy.

    PubMed

    Huang, Hsin-Yang; Hu, Shang-Hsiu; Hung, Shih-Ya; Chiang, Chih-Sheng; Liu, Hao-Li; Chiu, Tsung-Lang; Lai, Hsin-Yi; Chen, You-Yin; Chen, San-Yuan

    2013-11-28

    Nanobubbles can serve as promising, next-generation theranostic platforms for ultrasound (US) and magnetic resonance (MR) imaging, and combined magnetic targeting (MT) and high-intensity focused ultrasound (HIFU)-triggered drug release for tumor therapy. Nanobubble-based dual contrast enhancement agents encapsulated with perfluoropentane and stabilized with superparamagnetic iron oxide (SPIO) nanoparticles have been synthesized through a single-step emulsion process from thermosensitive F127 and polyacrylic acid (PAA). Both US and MR imaging contrast can be optimized by varying the shell thickness and SPIO-embedded concentration. The US contrast can be enhanced from a mean gray value of 62 to 115, and the MR r2 value can be enhanced from 164 to 208 (s(-1)mM (-1)Fe) by increasing the SPIO concentration from 14.1 to 28.2mg/mL, respectively. In vivo investigations of SPIO-embedded nanobubbles in excised tumors under external MT revealed that the US and MR signals change quantitatively compared to the same site without MT. This combined strategy enables the nanobubbles to enhance both passive targeting (increasing the permeability by HIFU) and physical MT of chemotherapeutic drugs to tumors. The integration of functionalities makes this nanobubble system a powerful and viable new tool to achieve simultaneous in vivo tumor imaging and efficacious cancer therapy. PMID:23933522

  8. Disinfection with peracetic acid (PAA), an alternative against fish pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of the lack of approved substances to treat fish diseases, disinfecting substances are tested to treat fish pathogens. These agents should not leave dangerous residues in the environment in order to successfully contribute to sustainable aquaculture. One of these substances is peracetic acid...

  9. Toxicity of peracetic acid (PAA) to tomonts of Ichthyophthirius multifiliis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The free-living infective theront of Ichthyophthirius multifiliis historically has been thought to be the only stage susceptible to treatment. A technique is introduced to determine the toxicity of compounds to the detached trophont, the settled tomont and the developing tomites within the tomont t...

  10. Toward Sci-φ: a lightweight Cloud PaaS for developing embarrassingly parallel applications based on Jini.

    PubMed

    Dazzi, Patrizio

    2014-01-01

    Embarrassingly parallel problems are characterised by a very small amount of information to be exchanged among the parts they are split in, during their parallel execution. As a consequence they do not require sophisticated, low-latency, high-bandwidth interconnection networks but can be efficiently computed in parallel by exploiting commodity hardware. Basically, this means cheap clusters, networks of workstations and desktops, and Computational Clouds. This computational model can be exploited to compute a quite large range of problems. This paper describes Sci-φ, an almost complete redesign of a previous tool of ours aimed at developing task parallel applications based on Java and Jini that were shown to be an effective and efficient solution in environments like clusters and networks of workstations and desktops. PMID:24701174

  11. EduCloud: PaaS versus IaaS Cloud Usage for an Advanced Computer Science Course

    ERIC Educational Resources Information Center

    Vaquero, L. M.

    2011-01-01

    The cloud has become a widely used term in academia and the industry. Education has not remained unaware of this trend, and several educational solutions based on cloud technologies are already in place, especially for software as a service cloud. However, an evaluation of the educational potential of infrastructure and platform clouds has not…

  12. Toward Sci-φ: A Lightweight Cloud PaaS for Developing Embarrassingly Parallel Applications Based on Jini

    PubMed Central

    2014-01-01

    Embarrassingly parallel problems are characterised by a very small amount of information to be exchanged among the parts they are split in, during their parallel execution. As a consequence they do not require sophisticated, low-latency, high-bandwidth interconnection networks but can be efficiently computed in parallel by exploiting commodity hardware. Basically, this means cheap clusters, networks of workstations and desktops, and Computational Clouds. This computational model can be exploited to compute a quite large range of problems. This paper describes Sci-φ, an almost complete redesign of a previous tool of ours aimed at developing task parallel applications based on Java and Jini that were shown to be an effective and efficient solution in environments like clusters and networks of workstations and desktops. PMID:24701174

  13. The influence of colloidal parameters on the specific power absorption of PAA-coated magnetite nanoparticles

    PubMed Central

    2011-01-01

    The suitability of magnetic nanoparticles (MNPs) to act as heat nano-sources by application of an alternating magnetic field has recently been studied due to their promising applications in biomedicine. The understanding of the magnetic relaxation mechanism in biocompatible nanoparticle systems is crucial in order to optimize the magnetic properties and maximize the specific absorption rate (SAR). With this aim, the SAR of magnetic dispersions containing superparamagnetic magnetite nanoparticles bio-coated with polyacrylic acid of an average particle size of ≈10 nm has been evaluated separately by changing colloidal parameters such as the MNP concentration and the viscosity of the solvent. A remarkable decrease of the SAR values with increasing particle concentration and solvent viscosity was found. These behaviours have been discussed on the basis of the magnetic relaxation mechanisms involved. PACS: 80; 87; 87.85jf PMID:21711915

  14. Materials Data on PaAs2 (SG:129) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. PAA-derived gold nanorods for cellular targeting and photothermal therapy.

    PubMed

    Kirui, Dickson K; Krishnan, Sushmitha; Strickland, Aaron D; Batt, Carl A

    2011-06-14

    A single-step LbL procedure to functionalize CTAB-capped GNRs via electrostatic self-assembly is reported. This approach allows for consistent biomolecule/GNR coupling using standard carboxyl-amine conjugation chemistry. The focus is on cancer-targeting biomolecule/GNR conjugates and selective photothermal destruction of cancer cells by GNR-mediated hyperthermia and NIR light. GNRs were conjugated to a single-chain antibody selective for colorectal carcinoma cells and used as probes to demonstrate photothermal therapy. Selective targeting and GNR uptake in antigen-expressing SW 1222 cells were observed using fluorescence microscopy. Selective photothermal therapy is demonstrated using SW 1222 cells, where >62% cell death was observed after cells are treated with targeted A33scFv-GNRs. PMID:21438153

  16. Materials Data on PaAs (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-03-19

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Larger red-shift in optical emissions obtained from the thin films of globular proteins (BSA, lysozyme) - polyelectrolyte (PAA) complexes

    NASA Astrophysics Data System (ADS)

    Talukdar, Hrishikesh; Kundu, Sarathi; Basu, Saibal

    2016-09-01

    Globular proteins (lysozyme and BSA) and polyelectrolyte (sodium polyacrylic acid) are used to form protein-polyelectrolyte complexes (PPC). Out-of-plane structures of ≈30-60 nm thick PPC films and their surface morphologies have been studied by using X-ray reflectivity and atomic force microscopy, whereas optical behaviors of PPC and protein conformations have been studied by using UV-vis, photoluminescence and FTIR spectroscopy respectively. Our study reveals that thin films of PPC show a larger red-shift of 23 and 16 nm in the optical emissions in comparison to that of pure protein whereas bulk PPC show a small blue-shift of ≈3 nm. A small amount of peak-shift is found to occur due to the heat treatment or concentration variation of the polyelectrolyte/protein in bulk solution but cannot produce such film thickness independent larger red-shift. Position of the emission peak remains nearly unchanged with the film thickness. Mechanism for such larger red-shift has been proposed.

  18. Trends in the Prevalence of Marijuana, Cocaine, and Other Illegal Drug Use

    MedlinePlus

    ... and private schools throughout the United States. 1991 1993 1995 1997 Ever used marijuana (one or more ... 800 − CDC − INFO (800 − 232 − 4636). Percentages 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 ...

  19. Ultrasonic Velocity, Viscosity and Refractive Index Investigation on Interacting Blend Solutions of PAA (Poly Acrylic Acid) and PVA (Poly Vinyl Alcohol) in Solvent DMSO (Di methyl Sulphoxide)

    NASA Astrophysics Data System (ADS)

    Nagamani, Chakrala

    2010-11-01

    The present study provides a great insight into the major new research areas like Plasma research (which is yielding a greater understanding of the universe) and Nano Technology Research (which provides many practical uses like Drug Delivery System). The Ultrasonic Velocities, Viscosities and Refractive indices of Poly (Acrylic Acid) and Poly (Vinyl Alcohol) blends in DMSO solutions have been measured over a wide range of composition, concentration and at different temperatures. The variation of Ultrasonic Velocity, derived acoustical parameters, adiabatic compressibility, acoustic impedance, Rao number, molar compressibility and relaxation strength with composition of blend solution was found not linear. This non-linearity has been attributed to incompatibility in conformity with the earlier findings. This behavior was confirmed by Viscometric and interaction parameters studies, as well as by investigation of Refractive index studies. These investigations offer an entirely new and simple approach to the study of the compatibility of polymer blends which is in general obtained by sophisticated techniques of thermal dynamic mechanical and electron microscopic analysis.

  20. Monitoring the Switching of Single BSA-ATTO 488 Molecules Covalently End-Attached to a pH-Responsive PAA Brush.

    PubMed

    Akkilic, Namik; Molenaar, Robert; Claessens, Mireille M A E; Blum, Christian; de Vos, Wiebe M

    2016-09-01

    We describe a novel combination of a responsive polymer brush and a fluorescently labeled biomolecule, where the position of the biomolecule can be switched from inside to outside the brush and vice versa by a change in pH. For this, we grafted ultrathin, amino-terminated poly(acrylic acid) brushes to glass and silicon substrates. Individual bovine serum albumin (BSA) molecules labeled with fluorophore ATTO 488 were covalently end-attached to the polymers in this brush using a bis-N-succinimidyl-(pentaethylene glycol) linker. We investigated the dry layer properties of the brush-protein ensemble, and it is swelling behavior using spectroscopic ellipsometry. Total internal reflection fluorescence (TIRF) microscopy enabled us to study the distance-dependent switching of the fluorescently labeled protein molecules. The fluorescence emission from the labeled proteins ceased (out-state) when the polymer chains stretched away from the interface under basic pH conditions, and fluorescence recurred (in-state) when the chains collapsed under acidic conditions. Moreover, TIRF allowed us to study the fluorescence switching behavior of fluorescently labeled BSA molecules down to the single-molecule level, and we demonstrate that this switching is fast but that the exact intensity during the in-state is the result of a more random process. Control experiments verify that the switching behavior is directly correlated to the responsive behavior of the polymer brush. We propose this system as a platform for switchable sensor applications but also as a method to study the swelling and collapse of individual polymer chains in a responsive polymer brush. PMID:27525503

  1. Effect of experimental conditions on the yields during the copyrolysis of Mustafa Kemal Paa (MKP) Lignite (Turkey) with low-density polyethylene

    SciTech Connect

    Ali Sinag; Melike Sungur; Muammer Canel

    2006-08-15

    Copyrolysis of a Turkish lignite with low-density polyethylene (LDPE) is conducted in a tubular reactor. The effect of experimental conditions (temperature of 400-700{sup o}C, catalyst, LDPE contents of the mixture are 33, 50, and 67 wt %) on the formation of tar, gas, and char and their effects on the formation of phenol are investigated. The catalysts used are red mud (which is a waste product of an aluminum factory in Turkey), zeolite (Linde type A (LTA)), and K{sub 2}CO{sub 3}. Tar evolution is determined to be increased significantly by increasing the LDPE content of the coal-LDPE mixture during the pyrolysis. The effect of adding LDPE to the coal on the gas generation is not remarkable. An increase in temperature leads to increased gas yields. Phenol and phenol derivatives are the obstacles for the complete conversion of lignite to tar and gas. To investigate this negative effect of phenols on the yields, the phenols found in tar from coal pyrolysis are detected by gas chromatography-mass spectroscopy (GC-MS), and it is observed that phenolic structures detected in the tar obtained by individual pyrolysis of coal are dramatically decreased by adding polymer to the coal. The use of catalysts during the copyrolysis procedure leads to improved gas generation. The possible reasons of these variations are discussed. A remarkable synergetic effect between lignite and LDPE on the tar yields is also observed. 21 refs., 8 figs., 4 tabs.

  2. Salt-induced fabrication of superhydrophilic and underwater superoleophobic PAA-g-PVDF membranes for effective separation of oil-in-water emulsions.

    PubMed

    Zhang, Wenbin; Zhu, Yuzhang; Liu, Xia; Wang, Dong; Li, Jingye; Jiang, Lei; Jin, Jian

    2014-01-13

    Conventional polymer membranes suffer from low flux and serious fouling when used for treating emulsified oil/water mixtures. Reported herein is the fabrication of a novel superhydrophilic and underwater superoleophobic poly(acrylic acid)-grafted PVDF filtration membrane using a salt-induced phase-inversion approach. A hierarchical micro/nanoscale structure is constructed on the membrane surface and endows it with a superhydrophilic/underwater superoleophobic property. The membrane separates both surfactant-free and surfactant-stabilized oil-in-water emulsions under either a small applied pressure (<0.3 bar) or gravity, with high separation efficiency and high flux, which is one to two orders of magnitude higher than those of commercial filtration membranes having a similar permeation property. The membrane exhibits an excellent antifouling property and is easily recycled for long-term use. The outstanding performance of the membrane and the efficient, energy and cost-effective preparation process highlight its potential for practical applications. PMID:24307602

  3. Comparison of the toxicity of the peracetic acid formulations Wofasteril(c) E400, E250 and Lspez to Daphnia magna with emphasis on the effect of hydrogen peroxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Commercial peracetic acid (PAA) formulations are acidic mixtures of PAA, hydrogen peroxide (H2O2), acetic acid (AA), H2O and stabilizers to maintain equilibrium of the concentrations. Different PAA formulations show diverse PAA/H2O2 ratios, leading to potentially different toxicities at the same con...

  4. EFFECT OF DEXTRAN-graft-POLYACRYLAMIDE INTERNAL STRUCTURE ON FLOCCULATION PROCESS PARAMETERS

    SciTech Connect

    Bezugla, T.; Kutsevol, N.; Shyichuk, A.; Ziolkowska, D.

    2008-08-28

    Dextran-graft-Polyacrylamide copolymers (D-g-PAA) of brush-like architecture were tested as flocculation aids in the model kaolin suspensions. Due to expanded conformation the D-g-PAA copolymers are more effective flocculants than individual PAA with close molecular mass. The internal structure of D-g-PAA copolymers which is determined by number and length of grafted PAA chains, the distance between grafts, etc., has the significant influence on flocculation behavior of such polymers.

  5. Phosphonoacetic Acid-Resistant Herpes Simplex Virus Infection in Hairless Mice1

    PubMed Central

    Klein, Richard J.; Friedman-Kien, Alvin E.

    1975-01-01

    Phosphonoacetic acid (PAA)-resistant type 1 herpes simplex virus population was isolated by repeated passage of the virus in the presence of this inhibitor. Hairless mice infected percutaneously with the inhibitor-resistant or the parental inhibitor-susceptible virus were treated intraperitoneally with PAA and 9-β-d-arabinofuranosyl-adenine by using several different dosage schedules. Whereas 9-β-d-arabinofuranosyl-adenine was effective both in the PAA-susceptible and PAA-resistant herpes simplex virus-induced skin infection, PAA suppressed only the infection induced by the parental PAA-susceptible virus. PMID:166611

  6. Genetic analysis of phenylacetic acid catabolism in Arthrobacter oxydans CECT386.

    PubMed

    Navarro-Llorens, Juana María; Drzyzga, Oliver; Perera, Julián

    2008-07-01

    Arthrobacter oxydans CECT386 is a Gram-positive bacterium able to use either phenylacetic acid or phenylacetaldehyde as the sole carbon and energy source for aerobic growth. Genes responsible for the catabolism of these compounds have been located at two chromosomal regions and were organized in one isolated paaN gene and two putative paa operons, one consisting of the paaD, paaF, tetR and prot genes, and one consisting of the paaG, paaH, paaI, paaJ, paaK and paaB genes. The identity of the paaF and paaN genes was supported by functional complementation experiments. A comparison with the paa catabolic genes and/or gene clusters of other bacteria that degrade these aromatic compounds is presented. The results of this study broaden the knowledge regarding the range of metabolic potential of this strain and eventually make it attractive for environmental applications. PMID:18437357

  7. Cornell University's Entrepreneurship Education & Outreach Program: Evaluation and Proposal. A White Paper.

    ERIC Educational Resources Information Center

    Schlough, Charles; Streeter, Deborah H.

    In 1997-1999, the Department of Agriculture, Resource, and Managerial Economics of Cornell University's College of Agriculture and Life Sciences conducted an entrepreneurship education and outreach program that was based on the Premier FastTrac Curriculum, which is a model delivery tool for entrepreneurship education. In 1997-1998, the program was…

  8. Development of a Brief Measure of Career Development Influences Based on the Systems Theory Framework

    ERIC Educational Resources Information Center

    Bridgstock, Ruth

    2007-01-01

    This paper documents the initial development and validation of a brief quantitative measure of career development influences based on the Systems Theory Framework (STF) of career development (McMahon & Patton, 1995; Patton & McMahon, 1997, 1999, 2006). Initial exploratory factor analyses of pilot study data revealed a six-factor structure based on…

  9. Elevated CO2 alters plant & microbial communities in the shortgrass steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Doubling atmospheric carbon dioxide concentrations [CO2] in Open Top Chambers (OTC) installed over native Colorado shortgrass steppe increased the productivity of C3 grasses from 1997-1999, and progressively increased plant cover of Artemisia frigida, fringed sage, a common shrub of North American a...

  10. The Effects of Social Class and Ethnicity on Gender Differences in GCSE Attainment: A Secondary Analysis of the Youth Cohort Study of England and Wales 1997-2001

    ERIC Educational Resources Information Center

    Connolly, Paul

    2006-01-01

    This article is based upon a secondary analysis of three successive cohorts of the Youth Cohort Study of England and Wales and examines the effects of social class and ethnicity on gender differences in General Certificate of Secondary Education (GCSE) attainment for those who left school in 1997, 1999 and 2001 respectively. The article shows that…

  11. A Learning Framework for the Small Business Environment

    ERIC Educational Resources Information Center

    Kelliher, Felicity; Henderson, Joan Bernadette

    2006-01-01

    Purpose: The aim of this article is to offer insight into the factors affecting individual and organisational learning in a small business; specifically the identification of the learning relationships that are unique to the small business environment. Design/methodology/approach: The authors apply Crossan et al.'s (1997, 1999) Organisational…

  12. Contingent Work in the Late-1990s.

    ERIC Educational Resources Information Center

    Hipple, Steven

    2001-01-01

    In 1999, there were 5.6 million contingent workers; the number and proportion remained unchanged from 1997-1999. Contingency rate was highest for younger workers, part-time workers, women, blacks, and Hispanics. More than half would rather have noncontingent jobs. Compared with earlier data, they were more likely to have personal than economic…

  13. Alignment of Idaho State Standards With The Idaho Direct Mathematics Assessment In Grades 4, 6, and 8.

    ERIC Educational Resources Information Center

    Leffler, James

    2004-01-01

    The process used for this alignment was an abbreviated version of the alignment work and models developed by Norman L. Webb (1997, 1999, 2001, and 2002), and used in alignment studies of the Idaho state assessment system. While the full Webb alignment includes four dimensions, this study only considers two of the dimensions -- Depth of Knowledge…

  14. Testing the Link between Child Maltreatment and Family Violence among Police Officers

    ERIC Educational Resources Information Center

    Zavala, Egbert

    2013-01-01

    The purpose of this study is to document the relationship between physical abuse during childhood and family violence among a group of police officers from the Baltimore Police Department in the United States. Analyzing data from the Police and Domestic Violence in Police Families in Baltimore, Maryland, 1997-1999, this study found a positive…

  15. Preactivated thiomers: Permeation enhancing properties

    PubMed Central

    Wang, Xueqing; Iqbal, Javed; Rahmat, Deni; Bernkop-Schnürch, Andreas

    2012-01-01

    The study was aimed to prepare a series of poly(acrylic acid)-cysteine-2-mercaptonicotinic acid conjugates (preactivated thiomers) and to evaluate the influence of molecular mass or degree of preactivation with 2-mercaptonicotinic acid (2MNA) on their permeation enhancing properties. Preactivated thiomers with different molecular mass and different degree of preactivation were synthesized and categorized on the basis of their molecular mass and degree of preactivation as PAA100-Cys-2MNA (h), PAA250-Cys-2MNA (h), PAA450-Cys-2MNA (h), PAA450-Cys-2MNA (m) and PAA450-Cys-2MNA (l). In vitro permeation studies, the permeation enhancement ability for preactivated thiomers was ranked as PAA450-Cys-2MNA (h) > PAA250-Cys-2MNA (h) > PAA100-Cys-2MNA (h) on both Caco-2 cell monolayers and rat intestinal mucosa. Comparing the influence of degree of preactivation with 2MNA on permeation enhancement, the following order PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (m) ≈ PAA450-Cys-2MNA (l) on Caco-2 cell monolayers and PAA450-Cys-2MNA (m) > PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (l) on intestinal mucosa was observed. The Papp of sodium fluorescein was 5.08-fold improved on Caco-2 cell monolayers for PAA450-Cys-2MNA (h) and 2.46-fold improved on intestinal mucosa for PAA450-Cys-2MNA (m), respectively, in comparison to sodium fluorescein in buffer only. These results indicated that preactivated thiomers could be considered as a promising macromolecular permeation enhancing polymer for non-invasive drug administration. PMID:22960503

  16. Defining a Structural and Kinetic Rationale for Paralogous Copies of Phenylacetate-CoA Ligases from the Cystic Fibrosis Pathogen Burkholderia cenocepacia J2315*

    PubMed Central

    Law, Adrienne; Boulanger, Martin J.

    2011-01-01

    The phenylacetic acid (PAA) degradation pathway is the sole aerobic route for phenylacetic acid metabolism in bacteria and facilitates degradation of environmental pollutants such as styrene and ethylbenzene. The PAA pathway also is implicated in promoting Burkholderia cenocepacia infections in cystic fibrosis patients. Intriguingly, the first enzyme in the PAA pathway is present in two copies (paaK1 and paaK2), yet each subsequent enzyme is present in only a single copy. Furthermore, sequence divergence indicates that PaaK1 and PaaK2 form a unique subgroup within the adenylate-forming enzyme (AFE) superfamily. To establish a biochemical rationale for the existence of the PaaK paralogs in B. cenocepacia, we present high resolution x-ray crystal structures of a selenomethionine derivative of PaaK1 in complex with ATP and adenylated phenylacetate intermediate complexes of PaaK1 and PaaK2 in distinct conformations. Structural analysis reveals a novel N-terminal microdomain that may serve to recruit subsequent PAA enzymes, whereas a bifunctional role is proposed for the P-loop in stabilizing the C-terminal domain in conformation 2. The potential for different kinetic profiles was suggested by a structurally divergent extension of the aryl substrate pocket in PaaK1 relative to PaaK2. Functional characterization confirmed this prediction, with PaaK1 possessing a lower Km for phenylacetic acid and better able to accommodate 3′ and 4′ substitutions on the phenyl ring. Collectively, these results offer detailed insight into the reaction mechanism of a novel subgroup of the AFE superfamily and provide a clear biochemical rationale for the presence of paralogous copies of PaaK of B. cenocepacia. PMID:21388965

  17. Growth inhibition of Aeromonas salmonicida and Yersinia ruckeri by disinfectants containing peracetic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is an agent used for disinfection in aquaculture. PAA contributes to sustainable aquaculture, because it releases no harmful residue in the environment. However, there is lack of guideline about the effective application of different PAA products against various pathogens in p...

  18. Peracetic acid oxidation of saline waters in the absence and presence of H ₂O ₂: secondary oxidant and disinfection byproduct formation.

    PubMed

    Shah, Amisha D; Liu, Zheng-Qian; Salhi, Elisabeth; Höfer, Thomas; von Gunten, Urs

    2015-02-01

    Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA-chloride and PAA-bromide reactions, second-order rate constants of (1.47 ± 0.58) × 10(-5) and 0.24 ± 0.02 M(-1) s(-1) were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H2O2), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H2O2] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA-iodide reaction) affected this process because it can react with H2O2 back to iodide. H2O2 is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 μM). In PAA-treated solutions with [H2O2] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr3), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 μg/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H2O2] < [PAA]. The same brackish waters, treated with PAA with [H2O2] ≫ [PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations. PMID:25611970

  19. Electrospun Poly(acrylic acid)/Silica Hydrogel Nanofibers Scaffold for Highly Efficient Adsorption of Lanthanide Ions and Its Photoluminescence Performance.

    PubMed

    Wang, Min; Li, Xiong; Hua, Weikang; Shen, Lingdi; Yu, Xufeng; Wang, Xuefen

    2016-09-14

    Combined with the features of electrospun nanofibers and the nature of hydrogel, a novel choreographed poly(acrylic acid)-silica hydrogel nanofibers (PAA-S HNFs) scaffold with excellent rare earth elements (REEs) recovery performance was fabricated by a facile route consisting of colloid-electrospinning of PAA/SiO2 precursor solution, moderate thermal cross-linking of PAA-S nanofiber matrix, and full swelling in water. The resultant PAA-S HNFs with a loose and spongy porous network structure exhibited a remarkable adsorption capacity of lanthanide ions (Ln(3+)) triggered by the penetration of Ln(3+) from the nanofiber surface to interior through the abundant water channels, which took full advantage of the internal adsorption sites of nanofibers. The effects of initial solution pH, concentration, and contact time on adsorption of Ln(3+) have been investigated comprehensively. The maximum equilibrium adsorption capacities for La(3+), Eu(3+), and Tb(3+) were 232.6, 268.8, and 250.0 mg/g, respectively, at pH 6, and the adsorption data were well-fitted to the Langmuir isotherm and pseudo-second-order models. The resultant PAA-S HNFs scaffolds could be regenerated successfully. Furthermore, the proposed adsorption mechanism of Ln(3+) on PAA-S HNFs scaffolds was the formation of bidentate carboxylates between carboxyl groups and Ln(3+) confirmed by FT-IR and XPS analysis. The well-designed PAA-S HNFs scaffold can be used as a promising alternative for effective REEs recovery. Moreover, benefiting from the unique features of Ln(3+), the Ln-PAA-S HNFs simultaneously exhibited versatile advantages including good photoluminescent performance, tunable emission color, and excellent flexibility and processability, which also hold great potential for applications in luminescent patterning, underwater fluorescent devices, sensors, and biomaterials, among others. PMID:27537710

  20. Identification of rose phenylacetaldehyde synthase by functional complementation in yeast.

    PubMed

    Farhi, Moran; Lavie, Orly; Masci, Tania; Hendel-Rahmanim, Keren; Weiss, David; Abeliovich, Hagai; Vainstein, Alexander

    2010-02-01

    Rose flowers, like flowers and fruits of many other plants, produce and emit the aromatic volatiles 2-phenylacetaldehyde (PAA) and 2-phenylethylalchohol (PEA) which have a distinctive flowery/rose-like scent. Previous studies in rose have shown that, similar to petunia flowers, PAA is formed from L: -phenylalanine via pyridoxal-5'-phosphate-dependent L: -aromatic amino acid decarboxylase. Here we demonstrate the use of a Saccharomyces cerevisiae aro10 mutant to functionally characterize a Rosa hybrida cv. Fragrance Cloud sequence (RhPAAS) homologous to petunia phenylacetaldehyde synthase (PhPAAS). Volatile headspace analysis of the aro10 knockout strain showed that it produces up to eight times less PAA and PEA than the WT. Expression of RhPAAS in aro10 complemented the yeast's mutant phenotype and elevated PAA levels, similar to petunia PhPAAS. PEA production levels were also enhanced in both aro10 and WT strains transformed with RhPAAS, implying an application for metabolic engineering of PEA biosynthesis in yeast. Characterization of spatial and temporal RhPAAS transcript accumulation in rose revealed it to be specific to floral tissues, peaking in mature flowers, i.e., coinciding with floral scent production and essentially identical to other rose scent-related genes. RhPAAS transcript, as well as PAA and PEA production in flowers, displayed a daily rhythmic behavior, reaching peak levels during the late afternoon hours. Examination of oscillation of RhPAAS transcript levels under free-running conditions suggested involvement of the endogenous clock in the regulation of RhPAAS expression in rose flowers. PMID:19882107

  1. Monitoring of organochlorine pesticides residues in green mussels (Perna viridis) from the coastal area of Thailand.

    PubMed

    Boonyatumanond, Ruchaya; Jaksakul, Areerat; Puncharoen, Pornthip; Tabucanon, Monthip Sriratana

    2002-01-01

    The utilization of organochlorine pesticides for pest control chemical has been of great interest on residue contamination from biological organisms in the environment. Green mussel (Perna viridis) samples were monitored as bioindicators for assessment of the water quality in coastal waters along the Gulf of Thailand. Thirty-six samples were collected from 12 stations during 1997-1999 and analysed for 26 organochlorine pesticide compounds. This paper focuses on the contamination of organochlorine pesticide residues in green mussel (P. viridis) during 1997-1999. The limit of detection of all organochlorine pesticides compounds was at the range of 0.1-8.3 ng g(-1) wet weight and recovery 75-95%. The concentration of organochlorine pesticides residues in green mussel was lower than the maximum residue limit for aquatic animals as recommended by the Ministry of Public Health of Thailand. The trend of organochlorine pesticide residue contamination in this area decreased from 1989 to 1999. PMID:12152831

  2. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants.

    PubMed

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-Ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-08-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins. PMID:26076971

  3. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants

    PubMed Central

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-01-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins. PMID:26076971

  4. In vitro free radical scavenging activity of platinum nanoparticles

    NASA Astrophysics Data System (ADS)

    Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Takahashi, Kyoko; Mashino, Tadahiko; Miyamoto, Yusei

    2009-11-01

    A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 ± 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical (\\mathrm {AOO}^{\\bullet } ) generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O2 and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by \\mathrm {AOO}^{\\bullet } generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 µM DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 µM DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

  5. Matrix tablets based on thiolated poly(acrylic acid): pH-dependent variation in disintegration and mucoadhesion.

    PubMed

    Guggi, Davide; Marschütz, Michaela K; Bernkop-Schnürch, Andreas

    2004-04-15

    This study examined the influence of the pH on the mucoadhesive and cohesive properties of polyarcylic acid (PAA) and thiolated PAA. The pH of PAA (molecular mass: 450 kDa) and of a corresponding PAA-cysteine conjugate was adjusted to 3, 4, 5, 6, 7 and 8. The amount of immobilised thiol groups and disulfide bonds was determined via Ellman's reagent. Tablets were compressed out of each pH-batch of both thiolated and unmodified PAA and the swelling behaviour, the disintegration time and the mucoadhesiveness were evaluated. The amount of thiol/disulfide groups per gram thiolated PAA of pH 3 and pH 8 was determined to be 332 +/- 94 micromol and 162 +/- 46 micromol, respectively. The thiolated PAA tablets displayed a minimum four-fold higher water uptake compared to unmodified PAA tablets. A faster and higher water uptake of both polymer types was observed above pH 5. Thiolated polymer tablets showed a 3-20-fold more prolonged disintegration time than unmodified PAA tablets. The cohesiveness of PAA-cysteine conjugate increased at higher pH, whereas the unmodified PAA behaved inversely. A 3-7-fold stronger mucoadhesiveness was observed for the PAA-cysteine conjugate tablets compared to unmodified PAA tablets. For both thiolated and unmodified polymer the mucoadhesiveness was 2-4-fold enhanced below pH 5. The difference in mucoadhesion between the two polymer types was most pronounced at these lower pH values. In this study substantial information regarding the pH-dependence of mucoadhesion and cohesion of unmodified polyacrylates and of thiolated polyacrylates is provided, representing helpful basic information for an ameliorated deployment of these polymers. PMID:15072786

  6. Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, Xuehui; Qiu, Yongsong; Du, Feiyan; Lin, Zhaojin; Sun, Dianrong; Huang, Shuolin

    2012-01-01

    Length-frequency data of eight commercial fish species in the Beibu Gulf (Golf of Tonkin), northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006-2007 than in 1997-1999: for four species ( Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus) it was lower in 2006-2007 than in 1997-1999, for two species ( Parargyrops edita and Trichiurus haumela) it remained the same, and for the other two species ( Trachurus japonicus and Decapterus maruadsi) it was higher in 2006-2007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.

  7. Functional genomics by NMR spectroscopy. Phenylacetate catabolism in Escherichia coli.

    PubMed

    Ismail, Wael; El-Said Mohamed, Magdy; Wanner, Barry L; Datsenko, Kirill A; Eisenreich, Wolfgang; Rohdich, Felix; Bacher, Adelbert; Fuchs, Georg

    2003-07-01

    Aerobic metabolism of phenylalanine in most bacteria proceeds via oxidation to phenylacetate. Surprisingly, the further metabolism of phenylacetate has not been elucidated, even in well studied bacteria such as Escherichia coli. The only committed step is the conversion of phenylacetate into phenylacetyl-CoA. The paa operon of E. coli encodes 14 polypeptides involved in the catabolism of phenylacetate. We have found that E. coli K12 mutants with a deletion of the paaF, paaG, paaH, paaJ or paaZ gene are unable to grow with phenylacetate as carbon source. Incubation of a paaG mutant with [U-13C8]phenylacetate yielded ring-1,2-dihydroxy-1,2-dihydrophenylacetyl lactone as shown by NMR spectroscopy. Incubation of the paaF and paaH mutants with phenylacetate yielded delta3-dehydroadipate and 3-hydroxyadipate, respectively. The origin of the carbon atoms of these C6 compounds from the aromatic ring was shown using [ring-13C6]phenylacetate. The paaG and paaZ mutants also converted phenylacetate into ortho-hydroxyphenylacetate, which was previously identified as a dead end product of phenylacetate catabolism. These data, in conjunction with protein sequence data, suggest a novel catabolic pathway via CoA thioesters. According to this, phenylacetyl-CoA is attacked by a ring-oxygenase/reductase (PaaABCDE proteins), generating a hydroxylated and reduced derivative of phenylacetyl-CoA, which is not re-oxidized to a dihydroxylated aromatic intermediate, as in other known aromatic pathways. Rather, it is proposed that this nonaromatic intermediate CoA ester is further metabolized in a complex reaction sequence comprising enoyl-CoA isomerization/hydration, nonoxygenolytic ring opening, and dehydrogenation catalyzed by the PaaG and PaaZ proteins. The subsequent beta-oxidation-type degradation of the resulting CoA dicarboxylate via beta-ketoadipyl-CoA to succinyl-CoA and acetyl-CoA appears to be catalyzed by the PaaJ, PaaF and PaaH proteins. PMID:12846838

  8. Modification of polymeric substrates using surface-grafted nanoscaffolds

    NASA Astrophysics Data System (ADS)

    Thompson, Kimberlee Fay

    Surface grafting and modification of poly(acrylic acid) (PAA) were performed on nylon 6,6 carpet fibers to achieve permanent stain and soil resistance. PAA was grafted to nylon and modified with 1H, 1H-pentadecafluorooctyl amine (PDFOA) using an amidation agent, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM). The first goal was to optimize acrylamide modification of PAA in solution. Aqueous reactions with taurine, hydroxyethyl amine, and butyl amine progressed ˜100%, while PDFOA reactions in MeOH progressed ˜80%. Reaction products precipitated at 77% butyl or 52% PDFOA acrylamide contents. The second goal was to optimize the PAA grafting process. First, PAA was adsorbed onto nylon 6,6 films. Next, DMTMM initiated grafting of adsorbed PAA. PAA surface coverage was ˜78%, determined by contact angle analysis of the top 0.1--1 nm and x-ray photoelectron spectroscopy (XPS) analysis of the top 3--10 nm. The third goal was to modify PAA grafted nylon films with butyl amine and PDFOA. Randomly methylated beta-cyclodextrin (RAMEB) solubilized PDFOA in water. Contact angle detected ˜100% surface reaction for each amine, while XPS detected ˜77% butyl amine (H2O) and ˜50% for PDFOA (MeOH or H2O pH = 7) reactions. In H2O pH = 12, the PDFOA reaction progressed ˜89%, perhaps due to greater efficiency, access and solubility. The fourth goal was to perform surface depth profiling via angle-resolved XPS analysis (ARXPS). The PAA surface coverage from contact angle and XPS was confirmed. Further, adsorbed PAA was thicker than grafted PAA, supporting the theory that PAA adsorption occurs in thick layers onto nylon followed by DMTMM-activated spreading and grafting of thinner PAA layers across the surface. The PDFOA reaction in McOH produced a highly fluorinated but thin exterior and an unreacted PAA interior. The PDFOA reaction in H 2O pH = 12 produced a completely fluorinated exterior and highly fluorinated interior. Thus surface modification levels

  9. Structural and wetting properties of porous anodic alumina templates prepared by different electrolytes

    NASA Astrophysics Data System (ADS)

    Suchitra S., M.; Reddy, P. Ramana; Udayashankar, N. K.

    2016-05-01

    Porous anodic alumina (PAA) has been extensively studied in recent years due to their unique properties and applications for manufacturing nanostructured materials. In this article, we report our studies on structural and wetting properties of PAA membranes prepared using different electrolytes such as sulphuric, oxalic and phosphoric acids. The morphological parameters such as pore diameter and porosity were measured using SEM and analysed using image-J software. The structural investigation of PAA membranes was carried out through X-ray diffraction analysis and it was confirmed that PAA membranes were amorphous in nature. The wetting behaviour of PAA membranes were measured using contact angle measurement technique. The results show that PAA membranes were hydrophilic in nature with contact angles 26.03°, 35.21° and 42.0° for sulphuric, oxalic and phosphoric acids respectively.

  10. Cerebrospinal fluid levels of phenylacetic acid in mental illness: behavioral associations and response to neuroleptic treatment.

    PubMed

    Sharma, R P; Faull, K; Javaid, J I; Davis, J M

    1995-05-01

    Cerebrospinal fluid levels of phenylacetic acid (CSF PAA) were obtained from normal controls and from drug-free psychiatric inpatients (schizophrenia, major depression, mania, and schizoaffective disorder). Post-treatment CSF PAA levels were obtained from 16 patients after 4 weeks of neuroleptic treatment. Phenylacetic acid levels were higher in women and were significantly correlated with age. There were no differences in CSF PAA levels between the various diagnostic groups and no difference between the paranoid and the nonparanoid subtypes of schizophrenia. CSF PAA was significantly correlated with several measures of psychopathology, especially the Brief Psychiatric Rating Scale hostility/suspiciousness factor. Neuroleptic treatment did not result in significant PAA changes. These findings are discussed in light of the amphetamine-like role ascribed to phenylethylamine, the precursor of PAA. PMID:7639084

  11. Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

    PubMed

    Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

    2015-08-15

    A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved. PMID:25966389

  12. Dynamics of the layer-by-layer assembly of a poly(acrylic acid)-lanthanide complex colloid and poly(diallyldimethyl ammonium).

    PubMed

    Xu, Jiali; Wang, Zhiliang; Wen, Lingang; Zhou, Xianju; Xu, Jian; Yang, Shuguang

    2016-01-21

    Poly(acrylic acid) (PAA) and lanthanide (Ln) ions, such as Ce(3+), Eu(3+), and Tb(3+), were prepared as dispersed complex colloidal particles through three different protocols with rigorous control of the pH value and mixing ratio. The negatively charged PAA-Ln complex particles were layer-by-layer (LbL) assembled with positively charged poly(diallyldimethyl ammonium) (PDDA) to prepare a thin film. The film thickness growth is much quicker than PDDA/PAA film. Due to the incorporation of Ln(3+) ions, the film exhibits fluorescence. During LbL assembly, PDDA-PAA association based on electrostatic force and PAA-Ce association based on coordination are in competition, which leads to the LbL assembly of PDDA and PAA-Ln complex colloidal particles being a complicated dynamic process. PMID:26549538

  13. Targeted Release of Tobramycin from a pH-Responsive Grafted Bilayer Challenged with S. aureus

    PubMed Central

    Lee, Hyun-Su; Dastgheyb, Sana S.; Hickok, Noreen J.; Eckmann, David M.; Composto, Russell J.

    2015-01-01

    A stimuli-responsive, controlled release bilayer for the prevention of bacterial infection on biomaterials is presented. Drug release is locally controlled by the pH-responsiveness of the bilayer, comprised of an inner poly(acrylic acid) (PAA) monolayer grafted to a biomaterial and cross-linked with an outer chitosan (CH) brush. Tobramycin (TOB) is loaded in the inner PAA in part to minimize bacteria resistance. Because biofilm formation causes a decrease in local pH, TOB is released from PAA and permeates through the CH which is in contact with the biofilm. Antibiotic capacity is controlled by the PAA thickness which depends on PAA brush length and the extent of cross-linking between CH and PAA at the bilayer interface. This TOB-loaded, pH responsive bilayer exhibits significantly enhanced antibacterial activity relative to controls. PMID:25585173

  14. Synthesis and application of polyaminoamide as new paraffin inhibitor from vegetable oil

    PubMed Central

    2011-01-01

    In this work, a series of novel paraffin inhibitor, polyaminoamide (PAA), was designed and prepared by aminolysis and poly-condensation using soybean oil and canola oil as the raw material. The property of the PAAs as paraffin inhibitor was investigated, the results show several PAA samples are potent in paraffin inhibition, and PPC-2 is the most effective one. Besides, the paraffin crystal morphology analysis was carried out to provide the mechanism of paraffin inhibition. PMID:22152091

  15. Rapid 3D Patterning of Poly(acrylic acid) Ionic Hydrogel for Miniature pH Sensors.

    PubMed

    Yin, Ming-Jie; Yao, Mian; Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Wai, Ping-Kong A

    2016-02-17

    Poly(acrylic acid) (PAA), as a highly ionic conductive hydrogel, can reversibly swell/deswell according to the surrounding pH conditions. An optical maskless -stereolithography technology is presented to rapidly 3D pattern PAA for device fabrication. A highly sensitive miniature pH sensor is demonstrated by in situ printing of periodic PAA micropads on a tapered optical microfiber. PMID:26643765

  16. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-04-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film PAA/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.

  17. Agmatine-containing poly(amidoamine)s as a novel class of antiviral macromolecules: structural properties and in vitro evaluation of infectivity inhibition.

    PubMed

    Donalisio, Manuela; Ranucci, Elisabetta; Cagno, Valeria; Civra, Andrea; Manfredi, Amedea; Cavalli, Roberta; Ferruti, Paolo; Lembo, David

    2014-10-01

    Poly(amidoamine)s (PAAs) are multifunctional tert-amine polymers endowed with high structural versatility. Here we report on the screening of a minilibrary of PAAs against a panel of viruses. The PAA AGMA1 showed antiviral activity against herpes simplex virus, human cytomegalovirus, human papillomavirus 16, and respiratory syncytial virus but not against human rotavirus and vesicular stomatitis virus. The results suggest the contribution of both a polycationic nature and side guanidine groups in imparting antiviral activity. PMID:25092704

  18. Growth inhibition of Aeromonas salmonicida and Yersinia ruckeri by disinfectants containing peracetic acid.

    PubMed

    Meinelt, Thomas; Phan, Thy-My; Behrens, Sascha; Wienke, Andreas; Pedersen, Lars-Flemming; Liu, Dibo; Straus, David L

    2015-04-01

    Peracetic acid (PAA) is a therapeutic agent used for disinfection in aquaculture, but it must be investigated thoroughly in order to mitigate diseases without harming the fish. Successful disinfectants (like PAA) should not leave dangerous residues in the environment in order to successfully contribute to sustainable aquaculture. The aim of our study was to compare the effectiveness of 6 commercial PAA products with different molecular PAA:H2O2 ratios to reduce bacterial growth of Aeromonas salmonicida and Yersinia ruckeri and to determine effective concentrations and exposure times. All products reduced colony-forming units (CFUs) of A. salmonicida and Y. ruckeri. Products with higher molecular PAA:H2O2 ratios inhibited growth better than products with lower molecular PAA:H2O2 ratios at the same PAA concentration; this indicates that H2O2 is not the driving force in the reduction of A. salmonicida and Y. ruckeri growth by PAA in vitro. The practical application of the products with high molecular PAA:H2O2 ratios should be prioritized if these pathogens are diagnosed. PMID:25850398

  19. Globus platform-as-a-service for collaborative science applications

    DOE PAGESBeta

    Ananthakrishnan, Rachana; Chard, Kyle; Foster, Ian; Tuecke, Steven

    2014-03-13

    Globus, developed as Software-as-a-Service (SaaS) for research data management, also provides APIs that constitute a flexible and powerful Platform-as-a-Service (PaaS) to which developers can outsource data management activities such as transfer and sharing, as well as identity, profile and group management. By providing these frequently important but always challenging capabilities as a service, accessible over the network, Globus PaaS streamlines web application development and makes it easy for individuals, teams, and institutions to create collaborative applications such as science gateways for science communities. We introduce the capabilities of this platform and review representative applications.

  20. 50 CFR 665.141 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the following crustaceans: Samoan name English common name Scientific name Ula spiny lobster Panulirus marginatus, Panulirus penicillatus. Papata slipper lobster Scyllaridae. pa'a Kona crab Ranina...

  1. 50 CFR 665.141 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the following crustaceans: Samoan name English common name Scientific name Ula spiny lobster Panulirus marginatus, Panulirus penicillatus. Papata slipper lobster Scyllaridae. pa'a Kona crab Ranina...

  2. 50 CFR 665.141 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the following crustaceans: Samoan name English common name Scientific name Ula spiny lobster Panulirus marginatus, Panulirus penicillatus. Papata slipper lobster Scyllaridae. pa'a Kona crab Ranina...

  3. 50 CFR 665.141 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the following crustaceans: Samoan name English common name Scientific name Ula spiny lobster Panulirus marginatus, Panulirus penicillatus. Papata slipper lobster Scyllaridae. pa'a Kona crab Ranina...

  4. 50 CFR 665.141 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the following crustaceans: Samoan name English common name Scientific name Ula spiny lobster Panulirus marginatus, Panulirus penicillatus. Papata slipper lobster Scyllaridae. pa'a Kona crab Ranina...

  5. Polyacrylic acid modified upconversion nanoparticles for simultaneous pH-triggered drug delivery and release imaging.

    PubMed

    Jia, Xuekun; Yin, Jinjin; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Chen, Mian; Li, Yuhong

    2013-12-01

    A poly(acrylicacid)-modified NaYF4:Yb, Er upconversion nanoparticles (PAA-UCNPs) with dual functions of drug delivery and release imaging have been successfully developed. The PAA polymer coated on the surface of UCNPs serve as a pH-sensitive nanovalve for loading drug molecules via electrostatic interaction. The drug-loading efficiency of the PAA-UCNPs was investigated by using doxorubicin hydrochloride (DOX) as a model anticancer drug to evaluate their potential as a delivery system. Results showed loading and releasing of DOX from PAA-UCNPs were controlled by varying pH, with high encapsulation rate at weak alkaline conditions and an increased drug dissociation rate in acidic environment, which is favorable for construct a pH-responsive controlled drug delivery system. The in vitro cytotoxicity test using HeLa cell line indicated that the DOX loaded PAA-UCNPs (DOX@PAA-UCNPs) were distinctly cytotoxic to HeLa cells, while the PAA-UCNPs were highly biocompatible and suitable to use as drug carriers. Furthermore, the upconversion fluorescence resonance energy transfer (UFRET) imaging through the two-photon laser scanning microscopy (TLSM) revealed the time course of intracellular delivery of DOX from DOX@PAA-UCNPs. Thus, PAA-UCNPs are effective for constructing pH-responsive controlled drug delivery systems for multi-functional cancer therapy and imaging. PMID:24266261

  6. [Metabolism of pantothenic acid and its derivatives in animals deficient in this enzyme].

    PubMed

    Gurinovich, V A; Moiseenok, A G

    1987-01-01

    Distribution of [14C]labelled metabolites of pantothenic acid (PAA) has been studied in tissues of normal and PAA-deficient rats-weaners 6 h after single injection of the calcium pantothenate (PAA-Ca), calcium 4'-phosphopantothenate (PAA-Ca) or pantethine (PT) preparations. Essential differences in the intertissue distribution of vitamin derivatives to be injected are revealed against a background of a higher vitamin-retaining ability of the PAA-deficient tissues. A degree of radionuclides' biotransformation into CoA permits them to be arranged in the series: PPA-Ca greater than PAA-Ca greater than PT. In PAA-deficient animals which were injected labelled PPA-Ca up to 41% of the liver radioactivity is concentrated in the CoA fraction and the quantity of label in the composition of PAA-protein cytosolium complexes increases considerably. It is supposed that there is a special PAA-depositing system which provides the intracellular CoA biosynthesis. PMID:3686695

  7. Globus Platform-as-a-Service for Collaborative Science Applications

    PubMed Central

    Ananthakrishnan, Rachana; Chard, Kyle; Foster, Ian; Tuecke, Steven

    2014-01-01

    Globus, developed as Software-as-a-Service (SaaS) for research data management, also provides APIs that constitute a flexible and powerful Platform-as-a-Service (PaaS) to which developers can outsource data management activities such as transfer and sharing, as well as identity, profile and group management. By providing these frequently important but always challenging capabilities as a service, accessible over the network, Globus PaaS streamlines web application development and makes it easy for individuals, teams, and institutions to create collaborative applications such as science gateways for science communities. We introduce the capabilities of this platform and review representative applications. PMID:25642152

  8. Study of bone-like hydroxyapatite/polyamino acid composite materials for their biological properties and effects on the reconstruction of long bone defects

    PubMed Central

    Yan, Ling; Jiang, Dian-ming

    2015-01-01

    Purpose The purpose of this study was to investigate the effect of bone-like hydroxyapatite/polyamino acid (BHA/PAA) in the osteogenesis and reconstruction of long segmental bone defects. Methods In vitro, MG63 cells were cultured with BHA/PAA. The osteoinductive activity of the BHA/PAA material was evaluated using inverted microscopy, scanning electron microscopy, MTT proliferation assay, and the determination of alkaline phosphatase activity and Ca2+ content. In vivo, the radial bone defect was made in 20 New Zealand White rabbits, and then these animal were randomly divided into two groups (n=10), the experimental group (with BHA/PAA) and the control group (without BHA/PAA). Postoperatively, the osteogenesis effect of BHA/PAA was evaluated through X-ray, hematoxylin–eosin staining, observation of the gross bone specimen, immunohistochemistry, and fluorescent confocal scanning microscopy. Results In vitro, BHA/PAA promoted the adhesion, growth, and calcium nodule formation of MG63 cells, and it had good osteogenesis activity. In vivo, with BHA/PAA material degradation and absorption, the new bone gradually formed, and the bone defect gradually recovered in the experimental group. In the control group, a limited bone formation was found at the bone broken ends, and the bone defect was obviously visible. Conclusion In vitro and in vivo, we confirmed that BHA/PAA was effective in inducing osteogenesis and reconstructing a long segmental bone defect. PMID:26719675

  9. An electrochemical sensor for nitrobenzene using π-conjugated polymer-embedded nanosilver.

    PubMed

    Kariuki, Victor M; Fasih-Ahmad, Sohaib A; Osonga, Francis J; Sadik, Omowunmi A

    2016-04-01

    A novel electrochemical sensing platform for nitrobenzene has been developed using silver nanoparticles (AgNPs) embedded in the poly(amic) acid (PAA) polymer matrix (PAA-AgNPs). PAA was synthesized via the polycondensation reaction of para-phenylenediamine and benzene-1,2,4,5-tetracarboxylic dianhydride. PAA-AgNP nanocomposites were synthesized by the in situ reduction of a silver precursor by the polymer at room temperature in a one-step approach without using an extraneous reducing or capping agent. The composite was subsequently characterized in solution and as a thin film. The X-ray diffraction technique revealed the crystalline nature of the PAA films with the embedded AgNPs. Unlike conventional polymers, the synthesized PAA membrane exhibits significant UV/Vis spectroscopic response. The sequestered nanoparticles also show the characteristic surface plasmon resonance (SPR) peaks confirming the presence of AgNPs. Integrated charge areas were 4.826 mC and 2.176 C for PAA/GC and PAA-AgNPs/GC respectively. The charge at the PAA-AgNP/GC electrode is 451 times greater than that at the PAA/GC electrode suggesting that the AgNP composite exhibits higher electroactivity. When tested as a sensor for nitrobenzene, the PAA-AgNP modified GC electrode showed promising potential as an electrochemical sensor. The electrochemical sensors exhibit a wide linear dynamic range (10-600 μM) with a correlation coefficient of 0.9735, a detection limit of 1.68 μM and a sensitivity of 7.88 μA μM(-1). The sensor also exhibited minimal interference effects on structurally-similar nitroaromatic compounds and metal species such as 4-nitroaniline (4-NA), 2-nitrophenol (2-NP), dinitrobenzene (DNB), Pb(2+) and Cd(2+). PMID:26936406

  10. In-Use Evaluation of Peracetic Acid for High-Level Disinfection of Endoscopes.

    PubMed

    Chenjiao, Wu; Hongyan, Zhang; Qing, Gu; Xiaoqi, Zhong; Liying, Gu; Ying, Fang

    2016-01-01

    Many high-level disinfectants have been used for disinfection of endoscopes such as 2% glutaraldehyde (GA), 0.55% ortho-phthalaldehyde (OPA), and peracetic acid (PAA). Both GA and OPA are widely used in disinfection of endoscopes and have been previously discussed, but there is little research on the practical use of PAA as an endoscope disinfectant. An experimental model of a flexible gastrointestinal endoscope being contaminated with 9 strains of microorganism was designed. After the cleaning and disinfecting procedure was completed, we evaluated the biocidal activity (850 ppm PAA, 2% GA, and 0.55% OPA) on our flexible gastrointestinal endoscope model. We also evaluated sterilization effectiveness of PAA on other bacteria, including some antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile). The residual bacterial colony count number of the PAA-disinfected endoscope was significantly lower than that of the GA- and OPA-disinfected endoscopes. The biocidal effect and efficiency of the endoscope disinfection by PAA appeared to be better than either the GA- or OPA-disinfected endoscope. PAA has demonstrated a good sterilization effect on other bacterial species; of particular note are common antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile. The results of this study demonstrate that PAA is a fast and effective high-level disinfectant for use in the reprocessing of flexible endoscopes. PMID:27070796

  11. Acetyl xylan esterase of Aspergillus ficcum catalyzed the synthesis of peracetic acid from ethyl acetate and hydrogen peroxide.

    PubMed

    Park, Seung-Moon

    2011-11-01

    Recombinant acetyl xylan esterase (rAXE) of Aspergillus ficcum catalyzed the synthesis of peracetic acid (PAA) from ethyl acetate and hydrogen peroxide. Ten micrograms of rAXE catalyzed the synthesis of 1.34 mM of PAA, which can be used for the pretreatment of cellulosic biomass in situ. PMID:21824816

  12. Language Proficiency as a Moderator Variable in Testing Academic Aptitude.

    ERIC Educational Resources Information Center

    Alderman, Donald L.

    1982-01-01

    Puerto Rican students took the Scholastic Aptitude Test (SAT), the Prueba de Aptitud Academica (PAA), and the Pruebas de Aprovechamiento Academico. The strength of the relationship between scores on the SAT given in English and the PAA given in Spanish increased as proficiency in English as a second language increased (Author/BW)

  13. Generation of avirulent Leishmania parasites and induction of nitric oxide production in macrophages by using polyacrylic acid.

    PubMed

    Elcicek, Serhat; Bagirova, Malahat; Allahverdiyev, Adil M

    2013-03-01

    Polyacrylic acid (PAA) is one of the anionic synthetic polyelectrolytes and is used in various immunological and pharmaceutical applications. PAA has been used as adjuvant in veterinary vaccines, in particular. However, to our knowledge, there are no studies that document immunostimulant properties of PAA in Leishmania infection. The main aim of this study was to investigate the interaction of Leishmania parasites with PAA: the possible effects on the infectivity of Leishmania promastigotes; and, induction of nitric oxide (NO) production in macrophages in vitro. The cytotoxicity of PAA on both macrophages and Leishmania infantum promastigotes were determined by MTT assay. NO production in the macrophage culture supernatant was measured by the Griess method. A significant, dose-dependent and time-dependent decrease in the infection index was observed after PAA exposure. The value of this decrease was found to be between 93% and 100% for all concentration and time points. PAA (molecular weight (MW) 30, 100 kDa at 1mg/1h)-exposed parasites stimulate NO production significantly at 48 h post-infection (PI), when compared to the control. This study demonstrates that Leishmania parasites lost their virulence upon interaction with PAA, and this interaction induced NO production in infected macrophages. These results may have important implications in the development of anti-leishmanial vaccines and amelioration of immune response. PMID:23238031

  14. Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

    PubMed

    Zhong, Ming; Liu, Yi-Tao; Liu, Xiao-Ying; Shi, Fu-Kuan; Zhang, Li-Qin; Zhu, Mei-Fang; Xie, Xu-Ming

    2016-06-28

    Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined. It is found that the mechanical properties of the PAA hydrogels are significantly influenced by the contents of covalent cross-linkers, Fe(3+) ions and water, which can be adjusted within a substantial range and thus broaden the applications of the hydrogels. Meanwhile, the PAA hydrogels have excellent recoverability based on the dynamic and reversible ionic cross-linking enabled by Fe(3+) ions. Moreover, the swelling capacity of the PAA hydrogels is as high as 1800 times in deionized water due to the synergistic effects of ionic and covalent cross-linkings. The combination of balanced mechanical properties, efficient recoverability, high swelling capacity and facile preparation provides a new method to obtain high-performance hydrogels. PMID:27230478

  15. Attraction of Plecia nearctica (dipter:bibionidae) to floral lures containing phenylacetaldehyde

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We observed that the floral odorant, phenylacetaldehyde (PAA), was attractive to both sexes of adult lovebugs (Plecia nearctica, Diptera: Bibionidae) in central and southern Florida. The addition of ß-myrcene and methyl salicylate to PAA did not improve the numbers of P. nearctica caught in delta tr...

  16. ASSAY FOR DETECTION AD ENUMERATION OF GENETICALLY ENGINEERED MICROORGANISMS WHICH IS BASED ON THE ACTIVITY OF A DEREGULATED 2,4-DICHLOROPHENOXYACETATE MONOOXYGENASE

    EPA Science Inventory

    An assay system was developed for the enumeration of genetically engineered microorganisms expressing a deregulated 2,4-dichlorophenoxyacetate (TFD) monooxygenase, which coverts phenoxyacetate (PAA) to phenol. n PAA-amended cultures of Pseudomonas aeruginosa PAO1C (pRO103) and Ps...

  17. Preparation and Biophysical Characterization of Poly(amidoamine) Dendrimer-Poly(acrylic acid) Graft.

    PubMed

    Dung, Tran Huu; Do, Le Thanh; Loan, Ta Thi; Yoo, Hoon

    2015-01-01

    A series of PAMAM dendrimer generation 5-poly(acrylic acid) grafts were prepared to evaluate the potential use of dendritic grafts as a drug encapsulated nanocarrier. The structural features of the synthesized polymer graft were identified by FT-IR and 1H-NMR spectra and the biophysical properties were characterized by measuring its particle size and zeta potential. The prepared dendrimer G5-PAA grafts had particle size in the range of 600 to 900 nm and the size increased proportionally with the number of PAA on dendrimer surface. The electrostatic property of the dendrimer G5-PAA, carried out by HPLC reversed phase column analysis and the measurement of zeta potential, revealed that both migration time and zeta potential were dependent on the number of grafted PAA. The number of free amino groups on dendrimer G5-PAA, determined quantitatively by fluorescamine assay, was in a reverse order with the reaction mole ratio of dendrimer to PAA. In addition, dendrimer G5-PAA showed a pH-dependent solubility in aqueous solution with characteristic pH region of solubility, depending on the dendrimer generation. The observed biophysical properties indicate that PAMAM dendrimer G5-PAA is promising as a drug encapsulated nanocarrier. PMID:26328427

  18. Peracetic acid is effective for controlling fungus on channel catfish eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is a relatively new compound suggested for use to treat pathogens in aquaculture. It is approved for use in Europe, but not in the United States. This study determined the effectiveness of PAA for fungus control on channel catfish Ictalurus punctatus eggs. The study consisted...

  19. Patients with abdominal aortic aneurysm have a high prevalence of popliteal artery aneurysms.

    PubMed

    Tuveson, Viktoria; Löfdahl, Hedvig E; Hultgren, Rebecka

    2016-08-01

    Patients with abdominal aortic aneurysms (AAA) are more prone to develop popliteal artery aneurysms (PAA), but the prevalence is not well known. Our aim was to investigate the prevalence of PAA in patients with AAA, and to determine whether a certain risk factor profile is more commonly found in patients with concurrent aneurysms. All AAA patients (ICD code I71.3, I71.4) attending the outpatient clinic at the Karolinska University Hospital between 2011 and 2013 were included in the study cohort (n=465); 48% (225) had been subjected to an ultrasound or computed tomography scan of their popliteal arteries. In these patients, three definitions of PAA were considered (⩾ 10.5, ⩾ 12, ⩾ 15 mm), although the overall analysis is based on PAA ⩾ 12 mm. The mean age was 70.7 years (SD 7.5), 89% were men, and the mean AAA diameter was 47 mm (SD 14). The prevalence of PAA was 19% (n=43) by definition ⩾ 12 mm, and 11% (n=25) with 15 mm. Claudication was more frequently found in AAA patients with PAA than patients without PAA. Sensitivity between clinical examination and radiology was 26%, and the specificity for clinical examination was 90%. In conclusion, owing to the high prevalence of PAA in AAA patients, described by us and others, the low cost and risks associated with ultrasound and the poor sensitivity at clinical examination, all women and men with AAA should undergo one radiological examination of their popliteal arteries. PMID:27216869

  20. Controlling fungus on channel catfish eggs with peracetic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is much interest in the use of peracetic acid (PAA) to treat pathogens in aquaculture. It is a relatively new compound and is approved for use in Europe, but not in the United States. This study determined the effectiveness of PAA for fungus control on channel catfish Ictalurus punctatus egg...

  1. Acute toxicity of peracetic acid to fish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA; also called peroxyacetic acid) is a stabilized mixture of acetic acid, hydrogen peroxide and water that does not leave dangerous residues in the environment when it breaks down as most compounds do. PAA is a promising disinfectant in the US aquaculture industry to control paras...

  2. Summary and Recommendations: Conference on Pacific/Asian American Families and HEW-Related Issues.

    ERIC Educational Resources Information Center

    J W K International Corp., Annandale, VA.

    The socioeconomic needs of Pacific and Asian American (PAA) families and Department of Health, Education, and Welfare programs having the most impact on the lives of PAAs are analyzed in this conference report. An overall outline of the conference proceedings, as well as reprints of all charts and papers presented, are included. The findings of…

  3. Polymide gas separation membranes

    DOEpatents

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

    2004-09-14

    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  4. Peracetic acid degradation in freshwater aquaculture systems and possible practical implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is a highly reactive peroxygen compound with wide-ranging antimicrobial effects and is considered an alternative sanitizer to formaldehyde. Products containing PAA are available in solution with acetic acid and hydrogen peroxide to maintain the stability of the chemical, and it...

  5. Polyamidoamine-grafted multiwalled carbon nanotubes for gene delivery: synthesis, transfection and intracellular trafficking.

    PubMed

    Liu, Min; Chen, Biao; Xue, Yanan; Huang, Jie; Zhang, Liming; Huang, Shiwen; Li, Qingwen; Zhang, Zhijun

    2011-11-16

    Functionalized multiwalled carbon nanotubes (f-MWNTs) are of great interest and designed as a novel gene delivery system. In this paper, we presented synthesis of polyamidoamine-functionalized multiwalled carbon nanotubes (PAA-g-MWNTs) and their application as a novel gene delivery system. The PAA-g-MWNTs, obtained from amide formation between PAA and chemically oxidized MWNTs, were stable in aqueous solution and much less toxic to cells than PAA and PEI 25KDa. More importantly, PAA-g-MWNTs showed comparable or even higher transfection efficiency than PAA and PEI at optimal w/w ratio. Intracellular trafficking of Cy3-labeled pGL-3 indicated that a large number of Cy3-labeled pGL-3 were attached to nucleus membrane, the majority of which was localized in nucleus after incubation with cells for 24 h. We have demonstrated that PAA modification of MWNTs facilitate higher DNA uptake and gene expression in vitro. All these facts suggest potential application of PAA-g-MWNTs as a novel gene vector with high transfection efficiency and low cytotoxicity. PMID:21995530

  6. Fish-friendly prophylaxis/disinfection in aquaculture: Low concentration of peracetic acid is stress-free to the carp (Cyprinus carpio) after repeated applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Application of peracetic acid (PAA) at low concentrations has been proved to be a broad functional and eco-friendly prophylaxis/disinfection method against various fish pathogens. Therefore, regular applications of low concentration PAA is sufficient to control (potential) pathogens in recirculatin...

  7. Characterization of the oxide formed in the presence of poly acrylic acid over the steam generator structural materials of nuclear power plants

    NASA Astrophysics Data System (ADS)

    Joshi, Akhilesh C.; Rufus, Appadurai L.; Suresh, Sumathi; Chandramohan, Palogi; Rangarajan, Srinivasan; Velmurugan, Sankaralingam

    2013-06-01

    On-line addition of polymeric dispersants, such as poly acrylic acid (PAA), to the steam generator (SG) results in the formation of a better protective inner oxide layer that reduces subsequent corrosion of structural materials. Its dispersive action inhibits the growth of a secondary oxide layer thereby facilitating their easy removal. This paper discusses the effect of PAA on the nature of oxides formed over the surfaces of SG. In the case of carbon steel, the inner oxide layer (magnetite) formed in the presence of PAA was protective. Electrochemical studies showed a minimum concentration of 350 ppb of PAA was found to be optimum. On the monel surface, in the absence of PAA, nickel ferrite was formed while in the presence of PAA, the oxide formed was a mixture of oxides of copper and nickel. A concentration of 700 ppb of PAA was found to be optimum for monel. In the case of incoloy, the effect of PAA was not discernible except for the size and morphology of the crystallites formed.

  8. Attractiveness of floral compounds to male and female moths in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of combinations of flower odor compounds in the field revealed several chemicals that were attractive or co-attractive with phenylacetaldehyde (PAA) to pest noctuid and pyralid moths. A number of moth species responded positively to PAA. The floral odorants cis-jasmone, linalool, benzyl a...

  9. Attractiveness of binary blends of floral odorant compounds to moths in Florida, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of combinations of flower odor compounds in the field revealed several chemicals that were attractive or co-attractive with phenylacetaldehyde (PAA) to pest noctuid and pyralid moths. A number of moth species responded positively to PAA. The floral odorants cis-jasmone, linalool, benzyl...

  10. Binary floral lure attractive to velvetbean caterpillar adults (Lepidoptera: Noctuidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A number of moth species responded positively to phenylacetaldehyde (PAA) and to the binary blend of PAA + linalool in tests conducted in peanut fields in northern Florida, USA. Velvetbean caterpillar moths (Anticarsia gemmatalis Hübner) were the most commonly collected species, with almost 13,000 ...

  11. Pulse vs. continuous treatment: which is better for applying peracetic acid in RAS?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is a promising disinfectant in aquaculture. It is highly effective against various fish pathogens and also environmentally friendly due to harmless degradation residues. However, knowledge about potential adverse effects of PAA disinfection on fish is lacking; practical guidelin...

  12. MUTAGENICITY AND DISINFECTION BY-PRODUCTS IN SURFACE DRINKING WATER DISINFECTED WITH PERACETIC ACID

    EPA Science Inventory

    The aims of this research were to study the influence of peracetic acid (PAA) on the formation of mutagens in surface waters used for human consumption and to assess its potential application for the disinfection of drinking water. The results obtained using PAA were compared to ...

  13. Effect of water hardness on peracetic toxicity to zebrafish, Danio rerio, embryos

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of peracetic acid (PAA) in aquaculture has been suggested as an alternative therapeutic agent as use of previous therapeutants becomes restricted. Few data are available concerning fish toxicity by PAA or factors that affect this toxicity. The aim of this study was to investigate the influ...

  14. Understanding the Adsorption Interface of Polyelectrolyte Coating on Redox Active Nanoparticles Using Soft Particle Electrokinetics and Its Biological Activity

    PubMed Central

    2015-01-01

    The application of cerium oxide nanoparticles (CNPs) for therapeutic purposes requires a stable dispersion of nanoparticles in a biological environment. The objective of this study is to tailor the properties of polyelectrolyte coated CNPs as a function of molecular weight to achieve a stable and catalytic active dispersion. The coating of CNPs with polyacrylic acid (PAA) has increased the dispersion stability of CNPs and enhanced the catalytic ability. The stability of PAA coating was analyzed using the change in the Gibbs free energy computed by the Langmuir adsorption model. The adsorption isotherms were determined using soft particle electrokinetics which overcomes the challenges presented by other techniques. The change in Gibbs free energy was highest for CNPs coated with PAA of 250 kg/mol indicating the most stable coating. The change in free energy for PAA of 100 kg/mol coated CNPs was 85% lower than the PAA of 250 kg/mol coated CNPs. This significant difference is caused by the strong adsorption of PAA of 100 kg/mol on CNPs. Catalytic activity of PAA-CNPs is assessed by the catalase enzymatic mimetic activity of nanoparticles. The catalase activity was higher for PAA coated CNPs as compared to bare CNPs which indicated preferential adsorption of hydrogen peroxide induced by coating. This indicates that the catalase activity is also affected by the structure of the coating layer. PMID:24673655

  15. Disinfection of water in recirculating aquaculture systems with peracetic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) has become a favoured alternative to chlorination in the disinfection of municipal waste water in recent years. It is also commonly used in the food industry as a disinfectant. Based on PAA concentration, the disulfide linkage in enzymes and proteins of microorganisms can be bro...

  16. Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?

    PubMed

    Cook, Sam D; Nichols, David S; Smith, Jason; Chourey, Prem S; McAdam, Erin L; Quittenden, Laura; Ross, John J

    2016-06-01

    The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway. PMID:27208245

  17. Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?1[OPEN

    PubMed Central

    Nichols, David S.; Smith, Jason; Chourey, Prem S.; McAdam, Erin L.; Quittenden, Laura

    2016-01-01

    The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA. However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway. PMID:27208245

  18. Enhancement of conductivity by diameter control of polyimide-based electrospun carbon nanofibers.

    PubMed

    Xuyen, Nguyen Thi; Ra, Eun Ju; Geng, Hong-Zhang; Kim, Ki Kang; An, Kay Hyeok; Lee, Young Hee

    2007-10-01

    Oxydianiline-pyromellitic dianhydride poly(amic acid) (ODA-PMDA PAA) was polymerized with a catalyst support of triethyl amine for controlling molecular weight. This polymer was used for electrospinning in the preparation of PAA nanofibers, a precursor of carbon nanofibers. Here the amount of catalyst and concentration of PAA solution were optimized to produce polyimide-based carbon nanofibers approximately 80 nm in diameter. The effects of molecular weight of PAA, bias voltage, and spinning rate on the morphology of electrospun PAA and polyimide nanofibers have been evaluated. We showed that the conductivity of the carbon nanofiber mat decreased with increasing nanofiber diameter, where the conductivity of polyimide-based carbon nanofiber mat was much higher than those of other types of carbon nanofiber mat. The key ingredient to increase conductivity in a carbon nanofiber mat was found to be the number of cross junctions between nanofibers. PMID:17850139

  19. A comparative study of different binders and their effects on electrochemical properties of LiMn2O4 cathode in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhian; Zeng, Tao; Lai, Yanqing; Jia, Ming; Li, Jie

    2014-02-01

    Physical and chemical properties of poly(vinylidene fluoride) (PVDF), sodium carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) binders are investigated in this paper, including functional group analysis, crystallinity and thermal properties. Then LiMn2O4 cathodes with four different binder systems (PAA binders/NMP solvent, PVDF binders/NMP solvent, PAA binders/H2O solvent and CMC binders/H2O solvent) are prepared, and their adhesion strengths, swelling properties, morphologies and electrochemical properties are studied. The results show that the LiMn2O4 cathode with PAA/NMP system displays the best cycle performances at both 25 °C and 55 °C among these four cathodes; the better capacity retention for LiMn2O4 cathode with PAA/NMP system is related to strong binding ability, appropriate swelling property and homogeneous distribution of particles inner the electrode.

  20. One-step synthesis of Poly(amic acid)/ZnO composite particles and its SERS applications

    NASA Astrophysics Data System (ADS)

    Wu, Jun Yi; Hsu, Keh-Ying

    2015-11-01

    Raspberry like structured PAA/ZnO microsphere were realized by coating the ZnO nanoparticles onto the surface of PAA microsphere via a novel solution method. The obtained materials were characterized by means of X-ray diffraction (XRD), scanning electron microscopy(SEM),transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) absorption measurement. It was shown that ZnO nanoparticles were successfully grown on the surface of PAA microsphere. The absorption band of PAA/ZnO raspberry microsphere showed a large redshift comparing to pure ZnO nanoparticles, indicating the strong interfacial interaction between PAA and ZnO. This approach was simple, mild and readily scaled up, affording a simple method for the synthesis of raspberry like structure. The resulting Poly(amic acid)/ZnO composite structures could be used as a substrate for surface enhanced Raman scattering(SERS).

  1. Synthesis, optical and structural properties of quantum-wells crystals grown into porous alumina

    NASA Astrophysics Data System (ADS)

    Zaghdoudi, W.; Dammak, T.; ElHouichet, H.; Chtourou, R.

    2014-07-01

    In this work, we present the confinement effect of the incorporation of perovskite compounds (C12H25-NH3)2PbI4 quantum wells into different porous anodic aluminum oxide (PAA) matrix via a chemical route. The detailed structure and optical property of the quantum wells in PAA were characterized by FT-IR, UV-Vis absorption and photoluminescence (PL) spectroscopy. The surface topography for the two used PAA matrix has been studied using atomic force microscopy (AFM). The pores diameters (pores spacing) for the two matrix are 15 (35 nm) and 45 (82 nm). UV-visible and photoluminescence spectroscopy of (C12H25-NH3)2PbI4/PAA exhibits a clear blue shift of the fundamental excitonic transition. This effect is attributed to the confinement of the exciton mode in the pore of the PAA matrix.

  2. Structural and morphological modifications of polymer thin film in the presence of nonsolvent

    NASA Astrophysics Data System (ADS)

    Talukdar, Hrishikesh; Kundu, Sarathi

    2016-05-01

    Thin films of sodium poly(acrylic acid) salt (Na-PAA) have been investigated to obtain the modification of the out-of-plane structure and surface morphology in the presence of toluene which is considered as nonsolvent for Na-PAA. X-ray reflectivity analysis show that the out-of-plane thickness of the Na-PAA film increases if the film is kept for longer time inside the toluene. For the thicker film the effect of toluene is more pronounced than the thinner one. Surface morphology obtained from the atomic force microscopy shows that the top surface becomes relatively rough after the dipping of the Na-PAA film inside toluene. Although toluene is nonsolvent for Na-PAA molecules, however, the effect of restructuring of the nanometer-thick polymer film cannot be ignored. The reason for such structural modification has been proposed.

  3. RAFT-synthesized Graft Copolymers that Enhance pH-dependent Membrane Destabilization and Protein Circulation Times

    PubMed Central

    Crownover, Emily; Duvall, Craig L.; Convertine, Anthony; Hoffman, Allan S.; Stayton, Patrick S.

    2012-01-01

    Here we describe a new graft copolymer architecture of poly(propylacrylic acid) (polyPAA) that displays potent pH-dependent, membrane-destabilizing activity and in addition is shown to enhance protein blood circulation kinetics. PolyPAA containing a single telechelic alkyne functionality was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization with an alkyne-functional chain transfer agent (CTA) and coupled to RAFT polymerized poly(azidopropyl methacrylate) (polyAPMA) through azide-alkyne [3+2] Huisgen cycloaddition. The graft copolymers become membrane destabilizing at endosomal pH values and are active at significantly lower concentrations than the linear polyPAA. A biotin terminated polyPAA graft copolymer was prepared by grafting PAA onto polyAPMA polymerized with a biotin functional RAFT CTA. The blood circulation time and biodistribution of tritium labeled avidin conjugated to the polyPAA graft copolymer was characterized along with a clinically utilized 40 kDa branched polyethylene glycol (PEG) also possessing biotin functionalization. The linear and graft polyPAA increase the area under the curve (AUC) over avidin alone by 9 and 12 times, respectively. Furthermore, polyPAA graft copolymer conjugates accumulated in tumor tissue significantly more than the linear polyPAA and the branched PEG conjugates. The collective data presented in this report indicate that the polyPAA graft copolymers exhibit robust pH-dependent, membrane-destabilizing activity, low cytotoxicity and significantly enhance blood circulation time and tumor accumulation. PMID:21699931

  4. Adsorption and aqueous lubricating properties of charged and neutral amphiphilic diblock copolymers at a compliant, hydrophobic interface.

    PubMed

    Røn, Troels; Javakhishvili, Irakli; Jankova, Katja; Hvilsted, Søren; Lee, Seunghwan

    2013-06-25

    We have investigated the adsorption and lubricating properties of neutral and charged amphiphilic diblock copolymers at a hydrophobic polydimethylsiloxane (PDMS) interface in an aqueous environment. The diblock copolymers consist of a hydrophilic block of either neutral poly(ethylene glycol) (PEG) or negatively charged poly(acrylic acid) (PAA) and of a hydrophobic block of polystyrene (PS) or poly(2-methoxyethyl acrylate) (PMEA), thus generating PEG-b-X or PAA-b-X, where X block is either PS or PMEA. The molecular weight ratios were roughly 1:1 with each block ca. 5 kDa. Comparing the neutral PEG and charged PAA buoyant blocks with all other conditions identical, the former showed superior adsorption onto nonpolar, hydrophobic PDMS surfaces from a neutral aqueous solution. PEG-based copolymers showed substantial adsorption for both PS and PMEA as the anchoring block, whereas PAA-based copolymers showed effective adsorption only when PMEA was employed as the anchoring block. For PAA-b-PS, the poor adsorption properties are chiefly attributed to micellization due to the high interfacial tension between the PS core and water. The poor lubricating properties of PAA-b-PS diblock copolymer for a PDMS-PDMS sliding contact was well correlated with the poor adsorption properties. PAA-b-PMEA copolymers, despite their sizable amount of adsorbed mass, showed insignificant lubricating effects. When the charges of the PAA-b-PMEA diblock copolymers were screened by either adding NaCl to the aqueous solution or by lowering the pH, both the adsorption and lubricity improved. We ascribe the poor adsorption and inferior aqueous lubricating properties of the PAA-based diblock copolymers compared to their PEG-based counterparts mainly to the electrostatic repulsion between charged PAA blocks, hindering the facile formation of the lubricating layer under cyclic tribological stress at the sliding PDMS-PDMS interface. PMID:23725290

  5. Systematic Investigation of Binders for Silicon Anodes: Interactions of Binder with Silicon Particles and Electrolytes and Effects of Binders on Solid Electrolyte Interphase Formation.

    PubMed

    Nguyen, Cao Cuong; Yoon, Taeho; Seo, Daniel M; Guduru, Pradeep; Lucht, Brett L

    2016-05-18

    The effects of different binders, polyvinylidene difluoride (PVdF), poly(acrylic acid) (PAA), sodium carboxymethyl cellulose (CMC), and cross-linked PAA-CMC (c-PAA-CMC), on the cycling performance and solid electrolyte interphase (SEI) formation on silicon nanoparticle electrodes have been investigated. Electrodes composed of Si-PAA, Si-CMC, and Si-PAA-CMC exhibit a specific capacity ≥3000 mAh/g after 20 cycles while Si-PVdF electrodes have a rapid capacity fade to 1000 mAh/g after just 10 cycles. Infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) reveal that PAA and CMC react with the surface of the Si nanoparticles during electrode fabrication. The fresh Si-CMC electrode has a thicker surface coating of SiOx than Si-PAA and Si-PAA-CMC electrodes, due to the formation of thicker SiOx during electrode preparation, which leads to lower cyclability. The carboxylic acid functional groups of the PAA binder are reactive toward the electrolyte, causing the decomposition of LiPF6 and dissolution of SiOx during the electrode wetting process. The PAA and CMC binder surface films are then electrochemically reduced during the first cycle to form a protective layer on Si. This layer effectively suppresses the decomposition of carbonate solvents during cycling resulting in a thin SEI. On the contrary, the Si-PVDF electrode has poor cycling performance and continuous reduction of carbonate solvents is observed resulting in the generation of a thicker SEI. Interestingly, the Lewis basic -CO2Na of CMC was found to scavenge HF in electrolyte. PMID:27135935

  6. Comparison of Performance Achievement Award Recognition With Primary Stroke Center Certification for Acute Ischemic Stroke Care

    PubMed Central

    Fonarow, Gregg C.; Liang, Li; Smith, Eric E.; Reeves, Mathew J.; Saver, Jeffrey L.; Xian, Ying; Hernandez, Adrian F.; Peterson, Eric D.; Schwamm, Lee H.

    2013-01-01

    Background Hospital certification and recognition programs represent 2 independent but commonly used systems to distinguish hospitals, yet they have not been directly compared. This study assessed acute ischemic stroke quality of care measure conformity by hospitals receiving Primary Stroke Center (PSC) certification and those receiving the American Heart Association's Get With The Guidelines‐Stroke (GWTG‐Stroke) Performance Achievement Award (PAA) recognition. Methods and Results The patient and hospital characteristics as well as performance/quality measures for acute ischemic stroke from 1356 hospitals participating in the GWTG‐Stroke Program 2010–2012 were compared. Hospitals were classified as PAA+/PSC+ (hospitals n=410, patients n=169 302), PAA+/PSC− (n=415, n=129 454), PAA−/PSC+ (n=88, n=26 386), and PAA−/PSC− (n=443, n=75 565). A comprehensive set of stroke measures were compared with adjustment for patient and hospital characteristics. Patient characteristics were similar by PAA and PSC status but PAA−/PSC− hospitals were more likely to be smaller and nonteaching. Measure conformity was highest for PAA+/PSC+ and PAA+/PSC− hospitals, intermediate for PAA−/PSC+ hospitals, and lowest for PAA−/PSC− hospitals (all‐or‐none care measure 91.2%, 91.2%, 84.3%, and 76.9%, respectively). After adjustment for patient and hospital characteristics, PAA+/PSC+, PAA+/PSC−, and PAA−/PSC+ hospitals had 3.15 (95% CIs 2.86 to 3.47); 3.23 (2.93 to 3.56) and 1.72 (1.47 to 2.00), higher odds for providing all indicated stroke performance measures to patients compared with PAA−/PSC− hospitals. Conclusions While both PSC certification and GWTG‐Stroke PAA recognition identified hospitals providing higher conformity with care measures for patients hospitalized with acute ischemic stroke, PAA recognition was a more robust identifier of hospitals with better performance. PMID:24125846

  7. Enhanced apatite-forming ability and antibacterial activity of porous anodic alumina embedded with CaO-SiO2-Ag2O bioactive materials.

    PubMed

    Ni, Siyu; Li, Xiaohong; Yang, Pengan; Ni, Shirong; Hong, Feng; Webster, Thomas J

    2016-01-01

    In this study, to provide porous anodic alumina (PAA) with bioactivity and anti-bacterial properties, sol-gel derived bioactive CaO-SiO2-Ag2O materials were loaded onto and into PAA nano-pores (termed CaO-SiO2-Ag2O/PAA) by a sol-dipping method and subsequent calcination of the gel-glasses. The in vitro apatite-forming ability of the CaO-SiO2-Ag2O/PAA specimens was evaluated by soaking them in simulated body fluid (SBF). The surface microstructure and chemical property before and after soaking in SBF were characterized. Release of ions into the SBF was also measured. In addition, the antibacterial properties of the samples were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that CaO-SiO2-Ag2O bioactive materials were successfully decorated onto and into PAA nano-pores. In vitro SBF experiments revealed that the CaO-SiO2-Ag2O/PAA specimens dramatically enhanced the apatite-forming ability of PAA in SBF and Ca, Si and Ag ions were released from the samples in a sustained and slow manner. Importantly, E. coli and S. aureus were both killed on the CaO-SiO2-Ag2O/PAA (by 100%) samples compared to PAA controls after 3 days of culture. In summary, this study demonstrated that the CaO-SiO2-Ag2O/PAA samples possess good apatite-forming ability and high antibacterial activity causing it to be a promising bioactive coating candidate for implant materials for orthopedic applications. PMID:26478362

  8. Conducting gel electrolytes with microporous structures for efficient quasi-solid-state dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yuan, Shuangshuang; Tang, Qunwei; He, Benlin; Yu, Liangmin

    2015-01-01

    Conducting gel electrolytes from poly(acrylic acid)-cetyltrimethylammonium bromide/polyaniline (PAA-CTAB/PANi) and poly(acrylic acid)-cetyltrimethylammonium bromide/polypyrrole (PAA-CTAB/PPy) are synthesized under driving forces of both osmotic pressure and capillary force within microporous PAA-CTAB matrix. The as-synthesized PAA-CTAB/PANi or PAA-CTAB/PPy can extend the reduction reaction of triiodides from gel electrolyte/Pt counter electrode interface to both interface and three-dimensional framework of conducting gel electrolyte due to the electrical conduction of PANi or PPy toward reflux electrons (electrons from external circuit to Pt counter electrode). The enhanced kinetics for triiodides → iodide conversion is promising in elevating photovoltaic performances of quasi-solid-state dye-sensitized solar cells (DSSCs). Driving forces by both osmotic pressure across PAA-CTAB matrix and capillary force presenting in micropores can elevate the loading of PANi or PPy incorporated liquid electrolyte in per unit volume, leading to further enhancement in charge transfer and electrocatalytic activity. The total power conversion efficiencies of 7.11% and 6.39% are recorded in the solar cells with PAA-CTAB/PANi and PAA-CTAB/PPy electrolytes under one sun irradiation, respectively, whereas it is 6.07% for the cell device with pure PAA-CTAB gel electrolyte. Electrical and electrochemical characterizations reveal that the electrical conduction and electrocatalytic performances have been significantly enhanced by incorporating electrical conducting PANi or PPy into microporous PAA-CTAB matrix. The concept opens a new approach of fabricating efficient polymer gel electrolytes for robust quasi-solid-state DSSC applications.

  9. Current status of quality in Japanese clinical trials.

    PubMed

    Saito, Kazuyuki; Kodama, Yasuo; Ono, Shunsuke; Mutoh, Mizue; Kawashima, Susumu; Fujimura, Akio

    2005-08-01

    The changes in the quality of Japanese clinical trials were evaluated by comparing the results of Good Clinical Practice (GCP) audits conducted from April 1997 to March 2000 (fiscal year (FY) 1997-1999) with those from April 2001 to March 2002 (FY2001). During both of the periods inspections were undertaken by the Organization for Pharmaceutical Safety and Research (OPSR). The audit findings in the former period were based on the audits that covered 331 hospitals and 775 trials conducted under the old GCP guideline. The audits in the latter period targeted 147 hospitals and 238 trials conducted under the old or new GCP guideline. The total number of deficiencies detected by GCP audits in the former three-year period (FY 1997-1999) was 1529, and the corresponding number in the latter single year (FY 2001) was 912. Two remarkable changes in OPSR's findings were observed between FY 1997-1999 and FY 2001 as follows; the proportion of protocol deviations increased from 14.7% (225/1529) to 53.1% (484/912), while the proportion of errors in case report forms (CRFs) decreased from 43.6% (666/1529) to 15.4% (140/912). The new GCP guideline sets very high standards for a hospital's qualification: to have sufficient equipment and hospital resources, to have capacity for promptly responding to urgent trial-related problems, to have an IRB, and to have appropriate staff including clinical research coordinators (CRCs) assigned to the clinical trial. Our results suggest that the impact of the regulatory changes of applicable standard is large for a hospital's qualification for conducting clinical trials in Japan. PMID:16054582

  10. Reliability of Japanese clinical trials estimated from GCP audit findings.

    PubMed

    Saito, K; Kodama, Y; Ono, S; Maida, C; Fujimura, A; Miyamoto, E

    2008-08-01

    To describe the reliability of Japanese clinical trials, we compared the results of a Good Clinical Practice (GCP) audit conducted between April 1997 and March 2000 (fiscal year (FY) 1997 - 1999) with those from April 2004 - March 2005 (FY2004). The number and proportion of various types of deficiencies described in GCP audit reports were compared between the 2 periods. The audit findings in the former period were based on official audits that covered 331 hospitals and 775 trials. The audits in the latter period targeted 114 hospitals and 189 trials. The inspection of former period was undertaken by the Organization for Pharmaceuticals Safety and Research (OPSR). On the other hand, the latter period was undertaken by the Pharmaceuticals and Medical Devices Agency (PMDA). The total number of deficiencies detected in GCP audits was 1,529 in the former 3-year period (FY1997 - 1999) and 819 in the latter period (FY2004). The total number of deficiencies detected and reported was more than 1.5-fold on an annual basis in the latter period. By category of deficiencies, the proportion of protocol deviations increased from 14.7 (225/1,529) to 45.7% (374/819), while the proportion of errors in case report forms (CRFs) decreased from 43.6 (666/ 1,529) to 27.1% (222/819). There were two remarkable changes in audit findings between FY1997 - 1999 and FY2004; the increase in the proportion of protocol deviations and the decrease in the proportion of CRF-related deficiencies. We think that in Japan the improvement of research environments is needed to provide reliable clinical data responsible for the regulatory standard of GCP. PMID:18793583

  11. Properties and mechanisms of drug release from matrix tablets containing poly(ethylene oxide) and poly(acrylic acid) as release retardants.

    PubMed

    Zhang, Feng; Meng, Fan; Lubach, Joseph; Koleng, Joseph; Watson, N A

    2016-08-01

    The interactions between poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) in aqueous medium at pH 6.8 were investigated in the current study. We have also studied the effect of interpolymer interactions and various formulation variables, including the molecular weight of PEO, the ratio between PEO and PAA, the crystallinity of PEO, and the presence of an acidifying agent, on the release of theophylline from matrix tablets containing both PEO and PAA as release retardants. At pH 6.8, the synergy in solution viscosity between PEO and PAA as the result of ion-dipole interaction was observed in this study. The release of theophylline from the matrix tablets containing physical mixtures of PEO and PAA was found to be a function of dissolution medium pH because of the pH-dependent interactions between these two polymers. Because of the formation of water insoluble interpolymer complex between PEO and PAA in aqueous medium at pH below 4.0, the release of theophylline was independent of PEO molecular weight and was controlled by Fickian diffusion mechanism in 0.01N hydrochloric acid solution. In comparison, the drug release was a function of PEO molecular weight and followed the anomalous transport mechanism in phosphate buffer pH 6.8. The presence of PAA exerted opposite effects on the release of theophylline in phosphate buffer pH 6.8. In one aspect, theophylline release was accelerated because the erosion of PAA was much faster than that of PEO at pH6.8. On the opposite aspect, theophylline release was slowed down because of the formation of insoluble complex inside the gel layer as the result of the acidic microenvironment induced by PAA, and the increase in the viscosity of the gel layer as the result of the synergy between PEO and PAA. These two opposite effects offset each other. As a result, the release of theophylline remained statistically the same even when 75% PEO in the formulation was replaced with PAA. In phosphate buffer pH 6.8, the release of

  12. Early epileptic encephalopathies including West syndrome: a 3-year retrospective study from Klang Hospital, Malaysia.

    PubMed

    Thambyayah, M

    2001-11-01

    It is difficult to give a country report from Malaysia. A study done in 1999 reported the incidence of West Syndrome to be 3% among newly diagnosed cases of epilepsy. In this 3 year retrospective hospital-based study (1997-1999), the prevalence of early epileptic encephalopathy (EEE) and West Syndrome were 4.1 and 2.5% respectively. There is difficulty classifying EEE cases into distinct sub-groups of EIEE (early infantile epileptic encephalopathy), WS (West Syndrome) and SMEI (severe myoclonic epilepsy of infancy), using a combination of clinical features, EEG and CT/MRI findings. PMID:11701263

  13. Prediction failure of a wolf landscape model

    USGS Publications Warehouse

    Mech, L.D.

    2006-01-01

    I compared 101 wolf (Canis lupus) pack territories formed in Wisconsin during 1993-2004 to the logistic regression predictive model of Mladenoff et al. (1995, 1997, 1999). Of these, 60% were located in putative habitat suitabilities 50% remained unoccupied by known packs after 24 years of recolonization. This model was a poor predictor of wolf re-colonizing locations in Wisconsin, apparently because it failed to consider the adaptability of wolves. Such models should be used cautiously in wolf-management or restoration plans.

  14. Social class inequalities in health among occupational cohorts from Finland, Britain and Japan: a follow up study.

    PubMed

    Lahelma, Eero; Pietiläinen, Olli; Rahkonen, Ossi; Kivimäki, Mika; Martikainen, Pekka; Ferrie, Jane; Marmot, Michael; Shipley, Martin; Sekine, Michikazu; Tatsuse, Takashi; Lallukka, Tea

    2015-01-01

    We examined whether relative occupational social class inequalities in physical health functioning widen, narrow or remain stable among white collar employees from three affluent countries. Health functioning was assessed twice in occupational cohorts from Britain (1997-1999 and 2003-2004), Finland (2000-2002 and 2007) and Japan (1998-1999 and 2003). Widening inequalities were seen for British and Finnish men, whereas inequalities among British and Finnish women remained relatively stable. Japanese women showed reverse inequalities at follow up, but no health inequalities were seen among Japanese men. Health behaviours and social relations explained 4-37% of the magnitude in health inequalities, but not their widening. PMID:25545770

  15. Materials compatibility for 238Pu-HNO3/HF solution containment: 238Pu aqueous processing

    NASA Astrophysics Data System (ADS)

    Reimus, M. A.; Pansoy-Hjelvik, M. E.; Silver, G.; Brock, J.; Nixon, J.; Ramsey, K. B.; Moniz, P.

    2000-07-01

    The Power Source Technologies Group at Los Alamos National Laboratory is building a 238Pu Aqueous Scrap Recovery Line at the Plutonium Facility. The process line incorporates several unit operations including dissolution, filtration, ion exchange, and precipitation. During 1997-1999, studies were carried out to determine the chemistry used in the full-scale process. Other studies focussed on the engineering design of the operation. Part of the engineering design was to determine, in compatibility studies, the materials for reaction and storage vessels which will contain corrosive 238Pu-HNO3/HF solutions. The full-scale line is to be operational by the end of year 2000.

  16. High quality polyacrylic acid modified multifunction luminescent nanorods for tri-modality bioimaging, in vivo long-lasting tracking and biodistribution

    NASA Astrophysics Data System (ADS)

    Yi, Zhigao; Lu, Wei; Liu, Hongrong; Zeng, Songjun

    2014-12-01

    Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging reveals that PAA-UCNRs can act as contrast agents for improved detection of the liver and spleen. In addition, a significant signal enhancement in the liver is observed in in vivo MRI, indicating that PAA-UCNRs are ideal T1-weighted MRI agents. More importantly, in vivo long-term tracking based on these PAA-UCNRs in the live mice and the corresponding ex vivo bioimaging of isolated organs also verify the translocation of PAA-UCNRs from the liver to the spleen, and the observed intense UC signals from the feces reveal the biliary excretion mechanism of these UCNRs. These findings contribute to understanding of the translocation and potential route for excretion of PAA-UCNRs, which can provide an important guide for the diagnosis and detection of diseases based on these UCNRs.Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging

  17. A simple method for decomposition of peracetic acid in a microalgal cultivation system.

    PubMed

    Sung, Min-Gyu; Lee, Hansol; Nam, Kibok; Rexroth, Sascha; Rögner, Matthias; Kwon, Jong-Hee; Yang, Ji-Won

    2015-03-01

    A cost-efficient process devoid of several washing steps was developed, which is related to direct cultivation following the decomposition of the sterilizer. Peracetic acid (PAA) is known to be an efficient antimicrobial agent due to its high oxidizing potential. Sterilization by 2 mM PAA demands at least 1 h incubation time for an effective disinfection. Direct degradation of PAA was demonstrated by utilizing components in conventional algal medium. Consequently, ferric ion and pH buffer (HEPES) showed a synergetic effect for the decomposition of PAA within 6 h. On the contrary, NaNO3, one of the main components in algal media, inhibits the decomposition of PAA. The improved growth of Chlorella vulgaris and Synechocystis PCC6803 was observed in the prepared BG11 by decomposition of PAA. This process involving sterilization and decomposition of PAA should help cost-efficient management of photobioreactors in a large scale for the production of value-added products and biofuels from microalgal biomass. PMID:25270405

  18. Analysis of Complexation Equilibria of Polyacrylic Acid by a Donnan-Based Concept

    PubMed

    Miyajima; Mori; Ishiguro

    1997-03-01

    Complexation equilibria of uni- and divalent metal ions (Ag+, Ca2+, Cu2+, and Pb2+) with polyacrylic acid (PAA) have been studied at various degrees of dissociation (alpha) of PAA under different sodium salt concentration levels at 25°C. Both pH and pM(MZ+ = Ag+, Ca2+, Cu2+, and Pb2+) of equilibrium mixture solutions of MZ+/PAA/Na+ (excess) have been determined concurrently by a potentiometric titration method. The electrostatic effect inherent in the polyion-metal ion binding equilibria has been evaluated by a Donnan-based concept and is corrected for by the use of a nonideality term of acid dissociation equilibria of the polyacid as a probe. For Ag+-PAA and Ca2+-PAA bindings, only monodentate ligand complexes, (MA)(Z-1), have proven to be formed, whereas for Cu2+ and Pb2+ ion bindings, formation of both monodentate and bidentate ligand complexes have been observed. For both Cu2+-PAA and Pb2+-PAA systems, bidentate carboxylate complex formation is predominant at alpha > ca. 0.3, whereas at alpha < ca. 0.3, formation of monodentate carboxylate complexes becomes appreciable as alpha decreases. Stability constants of these complexes together with the intra-molecular complexation equilibrium constants expressed by the ratio of the concentrations of bidentate complexes to monodentate complexes have successfully been evaluated and are compared with each other in order to discuss the multidentate complexation properties of the polycarboxylic acid. PMID:9245334

  19. In vitro apatite formation on porous anodic alumina induced by a phosphorylation treatment.

    PubMed

    Li, Xiaohong; Ni, Siyu; Webster, Thomas J

    2014-09-01

    In this study, a phosphorylation treatment of porous anodic alumina (PAA) was performed by wet impregnation in phosphoric acid and a subsequent heat treatment. The PAA and phosphorylated PAA specimens were analyzed using a field emission scanning electron microscope, an energy-dispersive X-ray spectrometer, and Fourier transform infrared spectroscopy. The apatite-forming ability of the phosphorylated PAA was evaluated by soaking the specimens in simulated body fluid for 1, 3, and 7 days. The surface microstructures and chemical property changes after soaking in simulated body fluid were again characterized by field emission scanning electron microscope, energy-dispersive X-ray spectrometer, and Fourier transform infrared spectroscopy. Results of this study demonstrated that the functional -PO4 groups introduced onto the PAA surface dramatically promoted the deposition of bone-like apatite on PAA. The results from this study indicated that the phosphorylation treatment of anodic alumina is an effective method for inducing bone-like apatite formation, and this phosphorylated PAA can be a promising candidate to be used as bioactive surface coatings on implant metals and alloys for orthopedic and dental applications. PMID:24598060

  20. Cellulose nanocrystal-filled poly(acrylic acid) nanocomposite fibrous membranes

    NASA Astrophysics Data System (ADS)

    Lu, Ping; Hsieh, You-Lo

    2009-10-01

    Nanocomposite fibrous membranes have been fabricated by electrospinning cellulose nanocrystal (CNC)-loaded poly(acrylic acid) (PAA) ethanol mixtures. Incorporating CNC in PAA significantly reduced fiber diameters and improved fiber uniformity. The average diameters of the as-spun nanocomposite fibers were significantly reduced from 349 nm to 162 nm, 141 nm, 90 nm and 69 nm at 5%, 10%, 15% and 20% CNC loading (by weight of a constant 4% PAA solution), respectively. CNC was well dispersed in the fibers as isolated rods oriented along the fiber axis and as spheres in the PAA matrix. The Young modulus and stress of the PAA/CNC nanocomposite fibers were significantly improved with increasing CNC loadings by up to 35-fold and 16-fold, respectively. Heat-induced esterification between the CNC surface hydroxyls and PAA carboxyl groups produced covalent crosslinks at the CNC-PAA interfaces, rendering the nanocomposite fibrous membranes insoluble in water, more thermally stable and far more superior in tensile strength. With 20% CNC, the crosslinked nanocomposite fibrous membrane exhibited a very impressive 77-fold increase in modulus and 58-fold increase in stress.

  1. Quercetin/β-cyclodextrin inclusion complex embedded nanofibres: Slow release and high solubility.

    PubMed

    Aytac, Zeynep; Kusku, Semran Ipek; Durgun, Engin; Uyar, Tamer

    2016-04-15

    Electrospinning of polyacrylic acid (PAA) nanofibres (NF) incorporating β-cyclodextrin inclusion complex (β-CD-IC) of quercetin (QU) was performed. Here, β-CD was used as not only the crosslinking agent for PAA nanofibres but also as a host molecule for inclusion of QU. The phase solubility test showed enhanced solubility of QU due to the inclusion complexation; in addition, the stoichiometry of QU/β-CD-IC was determined to be 1:1. Computational modelling studies confirmed that 1:1 and 1:2 complex formation are desirable; 1:1 complex formation was chosen to have higher weight loading of QU. SEM images showed that PAA/QU/β-CD-IC-NF were bead-free and uniform. XRD indicated that PAA/QU/β-CD-IC-NF were amorphous in nature without the crystalline peaks of QU. Comparative results revealed that the release profile of QU from PAA/QU/β-CD-IC-NF was much slower but greater in total than from PAA/QU/β-CD-IC-film. Moreover, high antioxidant activity and photostability of QU was achieved in PAA/QU/β-CD-IC-NF. PMID:26617028

  2. Understanding improved osteoblast behavior on select nanoporous anodic alumina.

    PubMed

    Ni, Siyu; Li, Changyan; Ni, Shirong; Chen, Ting; Webster, Thomas J

    2014-01-01

    The aim of this study was to prepare different sized porous anodic alumina (PAA) and examine preosteoblast (MC3T3-E1) attachment and proliferation on such nanoporous surfaces. In this study, PAA with tunable pore sizes (25 nm, 50 nm, and 75 nm) were fabricated by a two-step anodizing procedure in oxalic acid. The surface morphology and elemental composition of PAA were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis. The nanopore arrays on all of the PAA samples were highly regular. X-ray photoelectron spectroscopy analysis suggested that the chemistry of PAA and flat aluminum surfaces were similar. However, contact angles were significantly greater on all of the PAA compared to flat aluminum substrates, which consequently altered protein adsorption profiles. The attachment and proliferation of preosteoblasts were determined for up to 7 days in culture using field emission scanning electron microscopy and a Cell Counting Kit-8. Results showed that nanoporous surfaces did not enhance initial preosteoblast attachment, whereas preosteoblast proliferation dramatically increased when the PAA pore size was either 50 nm or 75 nm compared to all other samples (P<0.05). Thus, this study showed that one can alter surface energy of aluminum by modifying surface nano-roughness alone (and not changing chemistry) through an anodization process to improve osteoblast density, and, thus, should be further studied as a bioactive interface for orthopedic applications. PMID:25045263

  3. Pathophysiology and clinical implications of pulmonary arterial enlargement in COPD

    PubMed Central

    Wells, J Michael; Dransfield, Mark T

    2013-01-01

    Chronic obstructive pulmonary disease (COPD) is a complex condition defined by progressive airflow limitation in response to noxious stimuli, inflammation, and vascular changes. COPD exacerbations are critical events in the natural history of the disease, accounting for the majority of disease burden, cost, and mortality. Pulmonary vascular disease is an important risk factor for disease progression and exacerbation risk. Relative pulmonary artery enlargement on computed tomography scan, defined by a pulmonary artery to aortic (PA:A) ratio >1, has been evaluated as a marker of pulmonary vascular disease. The PA:A ratio can be measured reliably independent of electrocardiographic gating or the use of contrast, and in healthy patients a PA:A ratio >0.9 is considered to be abnormal. The PA:A ratio has been compared with invasive hemodynamic parameters, primarily mean pulmonary artery pressure in various disease conditions and is more strongly correlated with mean pulmonary artery pressure in obstructive as compared with interstitial lung disease. In patients without known cardiac or pulmonary disease, the PA:A ratio is predictive of mortality, while in COPD, an elevated PA:A ratio is correlated with increased exacerbation risk, outperforming other well established predictors of these events. Future studies should be aimed at determining the stability of the metric over time and evaluating the utility of the PA:A ratio in guiding specific therapies. PMID:24235822

  4. Structural tailoring of hydrogen-bonded poly(acrylic acid)/poly(ethylene oxide) multilayer thin films for reduced gas permeability.

    PubMed

    Xiang, Fangming; Ward, Sarah M; Givens, Tara M; Grunlan, Jaime C

    2015-02-01

    Hydrogen bonded poly(acrylic acid) (PAA)/poly(ethylene oxide) (PEO) layer-by-layer assemblies are highly elastomeric, but more permeable than ionically bonded thin films. In order to expand the use of hydrogen-bonded assemblies to applications that require a better gas barrier, the effect of assembling pH on the oxygen permeability of PAA/PEO multilayer thin films was investigated. Altering the assembling pH leads to significant changes in phase morphology and bonding. The amount of intermolecular hydrogen bonding between PAA and PEO is found to increase with increasing pH due to reduction of COOH dimers between PAA chains. This improved bonding leads to smaller PEO domains and lower gas permeability. Further increasing the pH beyond 2.75 results in higher oxygen permeability due to partial deprotonation of PAA. By setting the assembling pH at 2.75, the negative impacts of COOH dimer formation and PAA ionization on intermolecular hydrogen bonding can be minimized, leading to a 50% reduction in the oxygen permeability of the PAA/PEO thin film. A 20 bilayer coating reduces the oxygen transmission rate of a 1.58 mm natural rubber substrate by 20 ×. These unique nanocoatings provide the opportunity to impart a gas barrier to elastomeric substrates without altering their mechanical behavior. PMID:25519816

  5. Biodegradability and mechanical properties of poly(butylene succinate) composites with finely dispersed hydrophilic poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Mizuno, Sawako; Hotta, Atsushi

    2014-03-01

    Biodegradability and mechanical properties of aliphatic poly(butylene succinate) (PBS) films with finely dispersed hydrophilic poly(acrylic acid) (PAA) were investigated. First, 3.5 wt% of PAA was chemically grafted onto the surface of the PBS films (surface-grafted PBS) by photo grafting polymerization, and then the grafted PAA was homogeneously and finely dispersed into PBS by dissolving the surface-grafted PBS into chloroform before mixing and drying to get solid PAA-dispersed PBS. Degradation of these modified PBS was investigated using gel permeation chromatography (GPC) and tensile testing. According to the GPC results, it was found that the PAA-dispersed PBS had intermediate biodegradability with the intermediate water intake, and the reaction constant of PAA-dispersed PBS was in between those of untreated PBS and surface-grafted PBS, in fact 25% higher and 17% lower, respectively. The experimental results presented that the biodegradability of PBS could be well controlled by the dispersion of PAA, possibly leading to the widespread use of PBS for biodegradable polymers.

  6. Highly Sensitive and Selective In-Situ SERS Detection of Pb(2+), Hg(2+), and Cd(2+) Using Nanoporous Membrane Functionalized with CNTs.

    PubMed

    Shaban, Mohamed; Galaly, A R

    2016-01-01

    Porous Anodic Alumina (PAA) membrane was functionalized with CoFe2O4 nanoparticles and used as a substrate for the growing of very long helical-structured Carbon Nanotubes (CNTs) with a diameter less than 20 nm. The structures and morphologies of the fabricated nanostructures were characterized by field emission- scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and Raman spectroscopy. By uploading the CNTs on PAA, the characteristic Raman peaks of CNTs and PAA showed 4 and 3 times enhancement, respectively, which leads to more sensitive Surface-Enhanced Raman Spectroscopy (SERS) substrates. For comparison, PAA and CNTs/PAA arrays were used as SERS substrates for the detection of Hg(2+), Cd(2+), and Pb(2+). The proposed sensor demonstrated high sensitivity and selectivity between these heavy metal ions. CNTs/PAA sensor showed excellent selectivity toward Pb(2+) over other metal ions, where the enhancement factor is decreased from ~17 for Pb(2+) to ~12 for Hg(2+) and to ~4 for Cd(2+). Therefore, the proposed CNTs/PAA sensor can be used as a powerful tool for the determination of heavy metal ions in aqueous solutions. PMID:27143512

  7. Highly Sensitive and Selective In-Situ SERS Detection of Pb2+, Hg2+, and Cd2+ Using Nanoporous Membrane Functionalized with CNTs

    PubMed Central

    Shaban, Mohamed; Galaly, A. R.

    2016-01-01

    Porous Anodic Alumina (PAA) membrane was functionalized with CoFe2O4 nanoparticles and used as a substrate for the growing of very long helical-structured Carbon Nanotubes (CNTs) with a diameter less than 20 nm. The structures and morphologies of the fabricated nanostructures were characterized by field emission- scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and Raman spectroscopy. By uploading the CNTs on PAA, the characteristic Raman peaks of CNTs and PAA showed 4 and 3 times enhancement, respectively, which leads to more sensitive Surface-Enhanced Raman Spectroscopy (SERS) substrates. For comparison, PAA and CNTs/PAA arrays were used as SERS substrates for the detection of Hg2+, Cd2+, and Pb2+. The proposed sensor demonstrated high sensitivity and selectivity between these heavy metal ions. CNTs/PAA sensor showed excellent selectivity toward Pb2+ over other metal ions, where the enhancement factor is decreased from ~17 for Pb2+ to ~12 for Hg2+ and to ~4 for Cd2+. Therefore, the proposed CNTs/PAA sensor can be used as a powerful tool for the determination of heavy metal ions in aqueous solutions. PMID:27143512

  8. Poly(acrylic acid)-modified Fe3O4 microspheres for magnetic-targeted and pH-triggered anticancer drug delivery.

    PubMed

    Kang, Xiao-Jiao; Dai, Yun-Lu; Ma, Ping-An; Yang, Dong-Mei; Li, Chun-Xia; Hou, Zhi-Yao; Cheng, Zi-Yong; Lin, Jun

    2012-12-01

    Monodisperse poly(acrylic acid)-modified Fe(3)O(4) (PAA@Fe(3)O(4)) hybrid microspheres with dual responses (magnetic field and pH) were successfully fabricated. The PAA polymer was encapsulated into the inner cavity of Fe(3)O(4) hollow spheres by a vacuum-casting route and photo-initiated polymerization. TEM images show that the samples consist of monodisperse porous spheres with a diameter around 200 nm. The Fe(3)O(4) spheres, after modification with the PAA polymer, still possess enough space to hold guest molecules. We selected doxorubicin (DOX) as a model drug to investigate the drug loading and release behavior of as-prepared composites. The release of DOX molecules was strongly dependent on the pH value due to the unique property of PAA. The HeLa cell-uptake process of DOX-loaded PAA@Fe(3)O(4) was observed by confocal laser scanning microscopy (CLSM). After being incubated with HeLa cells under magnet magnetically guided conditions, the cytotoxtic effects of DOX-loaded PAA@Fe(3)O(4) increased. These results indicate that pH-responsive magnetic PAA@Fe(3)O(4) spheres have the potential to be used as anticancer drug carriers. PMID:23080514

  9. Effect of peracetic acid on biofilms formed by Staphylococcus aureus and Listeria monocytogenes isolated from dairy plants.

    PubMed

    Lee, S H I; Cappato, L P; Corassin, C H; Cruz, A G; Oliveira, C A F

    2016-03-01

    This research investigated the removal of adherent cells of 4 strains of Staphylococcus aureus and 1 Listeria monocytogenes strain (previously isolated from dairy plants) from polystyrene microtiter plates using peracetic acid (PAA, 0.5%) for 15, 30, 60, and 120 s, and the inactivation of biofilms formed by those strains on stainless steel coupons using the same treatment times. In the microtiter plates, PAA removed all S. aureus at 15 s compared with control (no PAA treatment). However, L. monocytogenes biofilm was not affected by any PAA treatment. On the stainless steel surface, epifluorescence microscopy using LIVE/DEAD staining (BacLight, Molecular Probes/Thermo Fisher Scientific, Eugene, OR) showed that all strains were damaged within 15 s, with almost 100% of cells inactivated after 30 s. Results of this trial indicate that, although PAA was able to inactivate both S. aureus and L. monocytogenes monospecies biofilms on stainless steel, it was only able to remove adherent cells of S. aureus from polystyrene microplates. The correct use of PAA is critical for eliminating biofilms formed by S. aureus strains found in dairy plants, although further studies are necessary to determine the optimal PAA treatment for removing biofilms of L. monocytogenes. PMID:26723125

  10. Highly Sensitive and Selective In-Situ SERS Detection of Pb2+, Hg2+, and Cd2+ Using Nanoporous Membrane Functionalized with CNTs

    NASA Astrophysics Data System (ADS)

    Shaban, Mohamed; Galaly, A. R.

    2016-05-01

    Porous Anodic Alumina (PAA) membrane was functionalized with CoFe2O4 nanoparticles and used as a substrate for the growing of very long helical-structured Carbon Nanotubes (CNTs) with a diameter less than 20 nm. The structures and morphologies of the fabricated nanostructures were characterized by field emission- scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and Raman spectroscopy. By uploading the CNTs on PAA, the characteristic Raman peaks of CNTs and PAA showed 4 and 3 times enhancement, respectively, which leads to more sensitive Surface-Enhanced Raman Spectroscopy (SERS) substrates. For comparison, PAA and CNTs/PAA arrays were used as SERS substrates for the detection of Hg2+, Cd2+, and Pb2+. The proposed sensor demonstrated high sensitivity and selectivity between these heavy metal ions. CNTs/PAA sensor showed excellent selectivity toward Pb2+ over other metal ions, where the enhancement factor is decreased from ~17 for Pb2+ to ~12 for Hg2+ and to ~4 for Cd2+. Therefore, the proposed CNTs/PAA sensor can be used as a powerful tool for the determination of heavy metal ions in aqueous solutions.

  11. Understanding improved osteoblast behavior on select nanoporous anodic alumina

    PubMed Central

    Ni, Siyu; Li, Changyan; Ni, Shirong; Chen, Ting; Webster, Thomas J

    2014-01-01

    The aim of this study was to prepare different sized porous anodic alumina (PAA) and examine preosteoblast (MC3T3-E1) attachment and proliferation on such nanoporous surfaces. In this study, PAA with tunable pore sizes (25 nm, 50 nm, and 75 nm) were fabricated by a two-step anodizing procedure in oxalic acid. The surface morphology and elemental composition of PAA were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis. The nanopore arrays on all of the PAA samples were highly regular. X-ray photoelectron spectroscopy analysis suggested that the chemistry of PAA and flat aluminum surfaces were similar. However, contact angles were significantly greater on all of the PAA compared to flat aluminum substrates, which consequently altered protein adsorption profiles. The attachment and proliferation of preosteoblasts were determined for up to 7 days in culture using field emission scanning electron microscopy and a Cell Counting Kit-8. Results showed that nanoporous surfaces did not enhance initial preosteoblast attachment, whereas preosteoblast proliferation dramatically increased when the PAA pore size was either 50 nm or 75 nm compared to all other samples (P<0.05). Thus, this study showed that one can alter surface energy of aluminum by modifying surface nano-roughness alone (and not changing chemistry) through an anodization process to improve osteoblast density, and, thus, should be further studied as a bioactive interface for orthopedic applications. PMID:25045263

  12. Use of bifunctional phosphonates for the preparation of heterobimetallic 5f-3d systems.

    PubMed

    Alsobrook, Andrea N; Zhan, Wei; Albrecht-Schmitt, Thomas E

    2008-06-16

    The hydrothermal reaction of phosphonoacetic acid (H2PO3CH2C(O)OH, PAA) with UO3 and Cu(C2H3O2)2 .H2O results in the formation of the crystalline heterobimetallic uranium(VI)/copper(II) phosphonates UO2Cu(PO3CH2CO2)(OH)(H2O)2 ( UCuPAA-1), (UO2) 2Cu(PO3CH2CO2)2(H2O)3 (UCuPAA-2), and [H3O][(UO2) 2Cu2(PO3CH2CO2)3(H2O)2 ( UCuPAA-3). The addition of sodium hydroxide to the aforementioned reactions results in the formation of Na[UO2(PO3CH2CO2)].2H2O (NaUPAA-1). These compounds display 1D (UCuPAA-1), 2D (UCuPAA-2, NaUPAA-1), and 3D (UCuPAA-3) architectures wherein the phosphonate portion of the ligand primarily coordinates the uranium(VI) centers; whereas the carboxylate moiety preferentially, but not exclusively, binds to the copper(II) ions. Fluorescence measurements on all four compounds demonstrate that the presence of copper(II) mostly quenches the emission from the uranyl moieties. PMID:18494466

  13. In Situ Characterization of Binary Mixed Polymer Brush-Grafted Silica Nanoparticles in Aqueous and Organic Solvents by Cryo-Electron Tomography.

    PubMed

    Fox, Tara L; Tang, Saide; Horton, Jonathan M; Holdaway, Heather A; Zhao, Bin; Zhu, Lei; Stewart, Phoebe L

    2015-08-11

    We present an in situ cryo-electron microscopy (cryoEM) study of mixed poly(acrylic acid) (PAA)/polystyrene (PS) brush-grafted 67 nm silica nanoparticles in organic and aqueous solvents. These organic-inorganic nanoparticles are predicted to be environmentally responsive and adopt distinct brush layer morphologies in different solvent environments. Although the self-assembled morphology of mixed PAA/PS brush-grafted particles has been studied previously in a dried state, no direct visualization of microphase separation was achieved in the solvent environment. CryoEM allows the sample to be imaged in situ, that is, in a frozen solvated state, at the resolution of a transmission electron microscope. Cryo-electron tomograms (cryoET) were generated for mixed PAA/PS brush-grafted nanoparticles in both N,N-dimethylformamide (DMF, a nonselective good solvent) and water (a selective solvent for PAA). Different nanostructures for the mixed brushes were observed in these two solvents. Overall, the brush layer is more compact in water, with a thickness of 18 nm, as compared with an extended layer of 27 nm in DMF. In DMF, mixed PAA/PS brushes are observed to form laterally separated microdomains with a ripple wavelength of 13.8 nm. Because of its lower grafting density than that of PAA, PS domains form more or less cylindrical or truncated cone-shaped domains in the PAA matrix. In water, PAA chains are found to form a more complete shell around the nanoparticle to maximize their interaction with water, whereas PS chains collapse into the core of surface-tethered micelles near the silica core. The cryoET results presented here confirm the predicted environmentally responsive nature of PAA/PS mixed brush-grafted nanoparticles. This experimental approach may be useful for the design of future mixed brush-grafted nanoparticles for nano- and biotechnology applications. PMID:26174179

  14. Behavior of Surface-Anchored Poly(acrylic acid) Brushes with Grafting Density Gradients on Solid Substrates: 1. Experiment

    SciTech Connect

    Wu,T.; Gong, P.; Szleifer, I.; Vicek, P.; Subr, V.; Genzer, J.

    2007-01-01

    We describe experiments pertaining to the formation of surface-anchored poly(acrylic acid) (PAA) brushes with a gradual variation of the PAA grafting densities on flat surfaces and provide detailed analysis of their properties. The PAA brush gradients are generated by first covering the substrate with a molecular gradient of the polymerization initiator, followed by the 'grafting from' polymerization of tert-butyl acrylate (tBA) from these substrate-bound initiator centers, and finally converting the PtBA into PAA. We use spectroscopic ellipsometry to measure the wet thickness of the grafted PAA chains in aqueous solutions at three different pH values (4, 5.8, and 10) and a series of ionic strengths (IS). Our measurements reveal that at low grafting densities, s, the wet thickness of the PAA brush (H) remains relatively constant, the polymers are in the mushroom regime. Beyond a certain value of s, the macromolecules enter the brush regime, where H increases with increasing s. For a given s, H exhibits a nonmonotonic behavior as a function of the IS. At large IS, the H is small because the charges along PAA are completely screened by the excess of the external salt. As IS decreases, the PAA enters the so-called salt brush (SB) regime, where H increases. At a certain value of IS, H reaches a maximum and then decreases again. The latter is a typical brush behavior in so-called osmotic brush (OB) regime. We provide detailed discussion of the behavior of the grafted PAA chains in the SB and OB regimes.

  15. Some mice feature 5th pharyngeal arch arteries and double-lumen aortic arch malformations.

    PubMed

    Geyer, Stefan H; Weninger, Wolfgang J

    2012-01-01

    A 5th pair of pharyngeal arch arteries (PAAs) has never been identified with certainty in mice. Murines in general are considered to not develop a 5th pair. If true, the significance of the mouse as a model for researching the genesis of malformations of the great intrathoracic arteries is limited. We aimed to investigate whether mouse embryos develop a 5th pair of PAAs and to identify malformations known to be caused by defective remodelling of the 5th PAAs. We employed the high-resolution episcopic microscopy method for creating digital volume data and three-dimensional (3D) computer models of the great intrathoracic arteries of 30 mouse embryos from days 12-12.5 post conception and 180 mouse fetuses from days 14.5 and 15.5 post conception. The 3D models of the fetuses were screened for the presence of a double-lumen aortic arch malformation. We identified such a malformation in 1 fetus. The 3D models of the embryos were analysed for the presence of 5th PAAs. Six of the 30 embryos (20%) showed a 5th PAA bilaterally, and an additional 9 (30%) showed a 5th PAA unilaterally. Our results prove that some mice do develop a 5th pair of PAAs. They also show that malformations which occur rarely in humans and result from defective remodelling of the left 5th PAA can be identified in mice as well. Thus, the mouse does represent an excellent model for researching the mechanisms driving PAA remodelling and the genesis of malformations of the great intrathoracic arteries. PMID:22287557

  16. Ionospheric Current Closure of the Pre-existing Auroral Arc

    NASA Astrophysics Data System (ADS)

    Jiang, F.; Kivelson, M.; Strangeway, R. J.; Khurana, K. K.; Walker, R. J.; Weygand, J. M.

    2014-12-01

    An auroral substorm commences when a discrete auroral arc brightens and subsequently expands poleward and azimuthally. The arc that brightens is usually the most equatorward of several auroral arcs that remain quiescent for ~5 to ~60 minutes before the break-up commences. This arc is often referred to as the "pre-existing auroral arc (PAA)" or the "growth-phase arc". Till now, the ionospheric electrodynamics of the PAA has been studied extensively by ground radar, rockets and low-altitude spacecraft, and it is well established that the field-aligned currents (FAC) associated with the PAA in the ionosphere are current sheets that are narrow in latitude and elongated in longitude. However, it remains a question whether the ionospheric currents that connect the FAC pair of the PAA are meridional or azimuthal. In this study, we have identified ~180 PAA events from FAST measurements in 1998 and 1999 and used the statistics to investigate the ionospheric current closure of the PAA. We calculate the height-integrated Pedersen currents from the electric fields measured by FAST using an empirical ionospheric conductance model and infer the FAC density from the divergence of the Pedersen currents. We find that in the vicinity of the PAA, the FAC density inferred from the divergence of perpendicular currents mimics the trend of the FAC density inferred from magnetic perturbations seen on FAST, and that the boundaries between the upward and the downward FAC sheets inferred from two different approaches lie very close together. Additionally, the latitudinal gradient of the azimuthal component of the magnetic perturbation is much larger than the azimuthal gradient of the meridional component of the magnetic perturbation in the vicinity of the PAA, indicating that the density of a meridional current is much larger than that of an azimuthal current. Our observational analysis strongly suggests that the perpendicular current that closes the FAC pair of the PAA is a north

  17. Natural attenuation potential of phenylarsenicals in anoxic groundwaters.

    PubMed

    Hempel, Michael; Daus, Birgit; Vogt, Carsten; Weiss, Holger

    2009-09-15

    The extensive production of chemical warfare agents in the 20th century has led to serious contamination of soil and groundwater with phenyl arsenicals at former ammunition depots or warfare agent production sites worldwide. Most phenyl arsenicals are highly toxic for humans. The microbial degradation of phenylarsonic acid (PAA) and diphenylarsinic acid (DPAA) was investigated in microcosms made of anoxic groundwater/sediment mixtures taken from different depths of an anoxic, phenyl arsenical contaminated aquifer in Central Germany. DPAA was not transformed within 91 days incubation time in any of the microcosms. The removal of PAA can be described by a first order kinetics without a lag-phase (rate: 0.037 d(-1)). In sterilized microcosms, PAA concentrations always remained stable, demonstrating that PAA transformation was a biologically mediated process. PAA transformation occurred under sulfate-reducing conditions due to sulfate consumption and production of sulfide. The addition of lactate (1 mM), a typical substrate of sulfate-reducing bacteria, increased the transformation rate of PAA significantly up to 0.134 d(-1). The content of total arsenic was considerably reduced (> 75%). Intermediates of PAA transformation were detected by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Experiments with a pure strain and sterile controls of Desulfovibrio gigas spiked with PAA showed that the elimination process is linked to the presence of sulfide formed through bacterial activity. Phenyl arsenicals were likely immobilized in the sedimentthrough sulfur substitution and a subsequent sulfur bond under the prevailing sulfate reducing condition. The results of this study indicate that PAA can undergo microbiologically mediated transformation in anoxic aquifers, leading to reduced concentrations in groundwater, which indicate a (enhancend) natural attenuation potential. PMID:19806732

  18. Precipitation of biomimetic fluorhydroxyapatite/polyacrylic acid nanostructures

    NASA Astrophysics Data System (ADS)

    Roche, Kevin J.; Stanton, Kenneth T.

    2015-01-01

    Ordered structures of fluorhydroxyapatite (FHA) nanoparticles that resemble the nanostructure of natural human enamel have been prepared. Wet precipitation in the presence of polyacrylic acid (PAA) was used, and the particle morphology was altered by varying several reaction conditions. High molecular weight PAA increased particle length from around 54 nm to several hundred nanometres, while maintaining particle width at 15 nm. PAA concentration and the order of mixing the reactants also influenced crystal morphology. Optimum conditions produced dense, aligned bundles of highly elongated nanorods, which are very similar to the hierarchical nanostructure of human tooth enamel.

  19. Co₉ Se₈ nanoplates as a new theranostic platform for photoacoustic/magnetic resonance dual-modal-imaging-guided chemo-photothermal combination therapy.

    PubMed

    Song, Xiao-Rong; Wang, Xiaoyong; Yu, Shu-Xian; Cao, Jianbo; Li, Shi-Hua; Li, Juan; Liu, Gang; Yang, Huang-Hao; Chen, Xiaoyuan

    2015-06-01

    A new theranostic platform is developed based on biocompatible poly(acrylic acid) (PAA)-Co9 Se8 nanoplates. These PAA-Co9 Se8 nanoplates are successfully utilized for photoacoustic imaging (PAI)/magnetic resonance imaging (MRI) dual-modal imaging. Moreover, the PAA-Co9 Se8 -DOX shows pH-responsive chemotherapy and enables the combination of photothermal therapy and chemotherapy to receive superior antitumor efficacy. This work promises further exploration of 2D nanoplatforms for theranostic applications. PMID:25885638

  20. Acid-catalytic decomposition of peracetic acid in the liquid phase

    SciTech Connect

    Kharchuk, V.G.; Kolenko, I.P.; Petrov, L.A.

    1985-12-01

    This paper elucidates the kinetic relationships of peracetic acid (PAA) decomposition in the presence of mineral acids and their heterogeneous analogs, polystyrene-di-vinylbenzene cation-exchangers, differing in physicochemical and morphological parameters. It is shown that the thermal decomposition of PAA in acetic acid is an acid-catalyzed reaction. The controlling step of the reaction is protonation of the substrate with formation of an active intermediate form. Sulfonated cation-exchangers are twice as effective as sulfuric acid in this process. Polystyrene-divinylbenzene sulfonated cation-exchangers can be used with success as acid catalysts in oxidation processes involving PAA, because of their high effectiveness, stability, and availability.

  1. MSFC MXER Tether Study

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Alexander, Reginald; Bonometti, Joseph; Chapman, Jack; Garza, Lucas; Glaese, John; Glasgow, Shaun; Guendel, Herb; Houston, Vance; Johnson, Paul

    2003-01-01

    This viewgraph presentation provides an overview of the proposed Momentum-eXchange/Electrodynamic Reboost (MXER) space hardware system. The tether system would be position cart-wheeling cables above the Earth and then, rotating like a giant sling, would capture spacecraft or payloads from space shuttles in low Earth orbits and launch them into higher orbits. This study focuses on system validation and structural design issues for MXER. Topics examined include: tether facility design, ED tether system, payload capture/catch mechanism, payload accomodations assembly (PAA), PAA rendezvous capability, and PAA capability to correct tether misthrows.

  2. Adsorption of sodium polyacrylate in high solids loading calcium carbonate slurries.

    PubMed

    Taylor, Joshua J; Sigmund, Wolfgang M

    2010-01-15

    The adsorption of sodium polyacrylate (NaPAA) in slurries with up to 75 wt.% calcium carbonate was investigated with the use of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and adsorption of probe molecules. Analysis of the IR spectra demonstrated that the carboxylate groups of NaPAA adsorbed onto ground calcium carbonate (GCC) in three different modes. These modes were shown to be dependent on the solids loading and age of the slurry. Further investigation lead to the determination of the chelating ability of NaPAA at high solids loading. PMID:19875128

  3. Poly(amidoamine) salt form: effect on pH-dependent membrane activity and polymer conformation in solution.

    PubMed

    Wan, Ka-Wai; Malgesini, Beatrice; Verpilio, Ilario; Ferruti, Paolo; Griffiths, Peter C; Paul, Alison; Hann, Anthony C; Duncan, Ruth

    2004-01-01

    On exposure to an acidic pH, linear poly(amidoamine)s (PAAs) cause membrane perturbation and consequently have potential as endosomolytic polymers for the intracellular delivery of genes and toxins. Previous studies used PAAs in the hydrochloride form only. The aim of this study was to investigate systematically the effect of the PAA counterion on pH-dependent membrane activity, general cytotoxicity, and PAA solution properties to help guide optimization of PAA structure for further development of PAA-protein conjugates. PAAs (ISA 1, 4, 22, and 23; M(w) 10000-50000 g/mol) were synthesized to provide a library of PAAs having different counterions including the acetate, citrate, hydrochloride, lactate, phosphate, and sulfate salts. pH-Dependent membrane activity was assessed using a rat red blood cell haemolysis assay (conducted at a starting pH of 7.4, 6.5, or 5.5; 1 mg/mL; 1 h), and general cytotoxicity was investigated using a murine melanoma cell line (B16F10) and a human bladder endothelial-like cell line (ECV-304). Whereas poly(ethyleneimine) was haemolytic at the starting pH of 7.4 at 1 h [ approximately 50% haemoglobin (Hb) release], none of the PAA salts were haemolytic at a starting pH of 7.4 or 6.5. Although PAA acetate, citrate, and lactate were also non-haemolytic at the starting pH of 5.5, the sulfate and hydrochloride forms caused significant haemolysis (up to 80% Hb release) and ISA 22 and 23 phosphate were also markedly haemolytic ( approximately 70% Hb release). These counterion-specific differences were also clearly visible using scanning electron microscopy, which was used to visualize the red blood cell morphology. All PAAs were relatively nontoxic (IC(50) >or= 300-5000 microg/mL) compared to poly-l-lysine (IC(50) = 2-10 microg/mL), the PAA hydrochloride salts produced the greatest cytotoxicity, and the B16F10 cells were more sensitive than the ECV-304 cells. Small-angle neutron scattering suggested that ISA 23 hydrochloride had a larger

  4. A Robust Polyionized Hydrogel with an Unprecedented Underwater Anti-Crude-Oil-Adhesion Property.

    PubMed

    Gao, Shoujian; Sun, Jichao; Liu, Pingping; Zhang, Feng; Zhang, Wenbin; Yuan, Shiling; Li, Jingye; Jin, Jian

    2016-07-01

    A polyionized hydrogel polymer (sodium polyacrylate-grafted poly(vinylidene fluoride) (PAAS-g-PVDF)) is fabricated via an alkaline-induced phase-inversion process. PAAS-g-PVDF coatings exhibit unprecedented anti-adhesion and self-cleaning properties to crude oils under an aqueous environment. A PAAS-g-PVDF-coated copper mesh can effectively separate a crude oil/water mixture with extremely high flux and high oil rejection driven by gravity, and is oil-fouling-free for long-term use. PMID:27159880

  5. Photoalignment efficiency enhancement of polyimide alignment layers by alkyl-amine vapor treatment

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kenji; Usami, Kiyoaki; Miki, Kazushi

    2014-08-01

    We have succeeded in enhancing the photoalignment efficiency of polyimide containing azobenzene in the backbone structure by exposing the corresponding precursor (polyamic acid: Azo-PAA) film to alkyl-amine vapor prior to photoalignment. The Azo-PAA film absorbed alky-amines and swelled by 300%. The photoinduced rotation of the Azo-PAA backbone structure occurred more easily in the swollen film. Most of the alkyl-amines in the swollen film desorbed during thermal imidization. As a result of the photoalignment efficiency enhancement, we also succeeded in expanding the controllable pretilt angle range of liquid crystals up to 38° without the appearance of threadlike disclination loops.

  6. High-speed growth and photoluminescence of porous anodic alumina films with controllable interpore distances over a large range

    NASA Astrophysics Data System (ADS)

    Li, Y. B.; Zheng, M. J.; Ma, L.

    2007-08-01

    Highly ordered porous anodic alumina (PAA) films are fabricated with high efficiency by stable high-field anodization in oxalic acid/ethanol/water electrolytes at 100-180V and sulfuric acid/oxalic acid/ethanol/water electrolytes at 30-80V, giving interpore distances in the range of 225-450nm and 70-140nm, respectively. The photoluminescence of PAA films prepared by high-field anodization shows remarkable redshift of the peak position and decrease of the intensity compared to that of PAA films formed by conventional low-field anodization.

  7. Controlled plasmon enhanced fluorescence by silver nanoparticles deposited onto nanotube arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenglong; Wu, Yanni; Dong, Jun; Gao, Wei; Han, Qingyan; Zheng, Hairong

    2016-09-01

    Three-dimensional (3D) plasmonic nanostructures of porous alumina array (PAA) with silver nanoparticles (AgNPs) were prepared for enhancing fluorescence emission. In order to avoid fluorescence quenching effects and obtain clear fluorescence enhancement, the molecules were separated by using such 3D substrates, and the mean distance between the molecules and nanoparticles’ surface can be easily controlled by changing the diameters of the PAA tube. It was found that the PAA tube with smaller size provides better fluorescence enhancement. Enhanced cross section, a new fluorescence enhanced factor, combined with the simulation of localized electromagnetic field enhancement was presented to understand the experimental results.

  8. Controlled plasmon enhanced fluorescence by silver nanoparticles deposited onto nanotube arrays.

    PubMed

    Zhang, Zhenglong; Wu, Yanni; Dong, Jun; Gao, Wei; Han, Qingyan; Zheng, Hairong

    2016-09-14

    Three-dimensional (3D) plasmonic nanostructures of porous alumina array (PAA) with silver nanoparticles (AgNPs) were prepared for enhancing fluorescence emission. In order to avoid fluorescence quenching effects and obtain clear fluorescence enhancement, the molecules were separated by using such 3D substrates, and the mean distance between the molecules and nanoparticles' surface can be easily controlled by changing the diameters of the PAA tube. It was found that the PAA tube with smaller size provides better fluorescence enhancement. Enhanced cross section, a new fluorescence enhanced factor, combined with the simulation of localized electromagnetic field enhancement was presented to understand the experimental results. PMID:27406632

  9. Understanding Humic Acid / Zr(IV) Interaction - A Spectromicroscopy Approach

    SciTech Connect

    Rothe, Joerg; Plaschke, Markus; Denecke, Melissa A.

    2007-02-02

    Complexation of Zr(IV) by humic acid (HA) and polyacrylic acid (PAA) is investigated from the point of view of the organic ligand. STXM Spectromicroscopy and C 1s-NEXAFS point to different interaction mechanisms between Zr(IV) cations and oxo/hydroxo colloids and PAA. Under conditions where the metal aquo ion is stable, strong complexes are formed. In contrast, unspecific surface coating is identified when PAA is contacted with Zr(IV) oxo/hydroxide colloids. HA exhibits similar C 1s-NEXAFS features indicating a complexation reaction.

  10. Collimated microfiber spectroscopy for optical characterization of disordered porous anodic alumina

    NASA Astrophysics Data System (ADS)

    Yoneda, Satoshi; Kimura, Saho; Yamaguchi, Akira; Kimura, Daiki; Ohkoshi, Yutaka; Yamanaka, Shigeru; Usami, Hisanao

    2016-02-01

    A novel collimated microfiber spectroscopy technique using an optical fiber probe with microball lens was developed to observe the photonic crystalline characteristics of porous anodized alumina (PAA) slabs with disordered arrays of holes. Transmittance spectra of the PAA slab observed by the microfiber probe with ball lens showed a broad valley at ∼410 nm; conversely, no significant valley was observed by an ordinary microfiber spectroscope without ball lens. The broad valley was comparable with that observed in a spectrum simulated for a model based on a scanning electron microscopy image of the PAA slab by using the finite-difference time-domain method.

  11. Persistent financial hardship, 11-year weight gain, and health behaviors in the Whitehall II study

    PubMed Central

    Conklin, Annalijn I; Forouhi, Nita G; Brunner, Eric J; Monsivais, Pablo

    2014-01-01

    Objective To ascertain prospectively gender-specific associations between types and amounts of financial hardship and weight gain, and investigate potential behavioral mechanisms. Methods Prospective study of 3701 adult British civil servants with repeated measures of difficulty paying bills or insufficient money to afford adequate for food/clothing (1985-1988; 1989-1990; 1991-1993; 1997-1999), and weight (1985-1988; 1997-1999). Results Persistent hardships were associated with adjusted mean weight change in women over 10.9 years, but no consistent pattern was seen in men. During follow-up, 46% of women gained ≥5 kg. Women reporting persistent insufficient money for food/clothing had a significantly greater odds of gaining ≥5 kg (1.42 [1.05, 1.92]) compared to no hardship history, which remained after socioeconomic status (SES) adjustment (1.45 [1.05, 2.01]). The association between persistent difficulty paying bills and odds of excess weight gain was also significant (1.42 [1.03, 1.97]) but attenuated after considering SES (1.39 [0.98, 1.97]). Four health behaviors as single measures or change variables did not attenuate associations. Conclusions Results suggested strategies to tackle obesity must address employed women's everyday financial troubles which may influence weight through more biological pathways than classical correlates of economic disadvantage and weight. PMID:25155547

  12. Preparation of poly(acrylic acid) particles by dispersion polymerization in an ionic liquid.

    PubMed

    Minami, Hideto; Kimura, Akira; Kinoshita, Keigo; Okubo, Masayoshi

    2010-05-01

    Poly(acrylic acid) (PAA) particles were successfully prepared by dispersion polymerization of acrylic acid in ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoro-methanesulfonyl)amide ([DEME][TFSA]) at 70 degrees C with low hydrolysis grade (35.4%) poly(vinyl alcohol) as stabilizer. Interestingly, the PAA particles were easily extracted as particle state with water. Thus, the PAA particles had a cross-linked structure during the polymerization without cross-linker. Moreover, it was also noted that the cross-linking density of the PAA particles could be controlled by thermal treatment at various temperatures in [DEME][TFSA] utilizing the advantages of nonvolatility and high thermal stability of the ionic liquid. PMID:20043688

  13. Surface Wave Velocity of Crosslinked Polyacrylate Gels

    NASA Astrophysics Data System (ADS)

    Matsuoka, Tatsuro; Kinouchi, Wataru; ShinobuKoda, ShinobuKoda; Nomura, Hiroyasu

    1999-05-01

    Surface wave velocities of crosslinked polyacrylate hydrogelswere measured as a function of water content with differentcompositions of sodium polyacrylate (NaPA) and polyacrylic acid (PAA).The water content and composition dependencies of the surface wavevelocity were discussed.

  14. A luminescent ultrathin film with reversible sensing toward pressure.

    PubMed

    Li, Mingwan; Tian, Rui; Yan, Dongpeng; Liang, Ruizheng; Wei, Min; Evans, David G; Duan, Xue

    2016-03-28

    A flexible ultrathin film based on alternate assembly of a sodium polyacrylate (PAA) modified styrylbiphenyl derivative (BTBS) and layered double hydroxide nanosheets is fabricated, which exhibits pressure-responsive photoluminescence with a high sensitivity and good reversibility. PMID:26950695

  15. Recent Progress in NIF Mandrel Production

    SciTech Connect

    Takagi, M; Cook, R; McQuillan, B; Nikroo, A

    2003-09-03

    The production of spherical poly({alpha}-methylstyrene) (P{alpha}MS) mandrels utilizes a small amount (<0.1wt%) of high-molecular-weight poly(acrylic acid) (PAA) in the suspending medium, which substantially increases the interfacial tension during curing relative to methods using poly(vinyl alcohol) (PVA). However, fully cured capsules made by this method displayed a significant level of high frequency surface debris that became especially problematic when the mandrels were subsequently overcoated. To solve this problem we examined the use of PAA in conjunction with PVA in order to reduce these surface features, and explored numerous variations of concentration and timing of the PVA addition. The optimum conditions were found to be initial use of PAA for centering and symmetry of the mandrels, followed by removal of the PAA medium, washing of the mandrels with water, and finally transfer to PVA solution for completion of the curing cycle.

  16. Salts of phenylacetic acid and 4-hydroxyphenylacetic acid with Cinchona alkaloids: Crystal structures, thermal analysis and FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Amombo Noa, Francoise M.; Jacobs, Ayesha

    2016-06-01

    Seven salts were formed with phenylacetic acid (PAA), 4-hydroxyphenylacetic acid (HPAA) and the Cinchona alkaloids; cinchonidine (CIND), quinidine (QUID) and quinine (QUIN). For all the structures the proton was transferred from the carboxylic acid of the PAA/HPAA to the quinuclidine nitrogen of the respective Cinchona alkaloid. For six of the salts, water was included in the crystal structures with one of these also incorporating an isopropanol solvent molecule. However HPAA co-crystallised with quinine to form an anhydrous salt, (HPAA-)(QUIN+). The thermal stability of the salts were determined and differential scanning calorimetry revealed that the (HPAA-)(QUIN+) salt had the highest thermal stability compared to the other salt hydrates. The salts were also characterized using Fourier transform infrared spectroscopy. (PAA-)(QUID+)·H2O and (PAA-)(QUIN+)·H2O are isostructural and Hirshfeld surface analysis was completed to compare the intermolecular interactions in these two structures.

  17. Probing the Mucoadhesive Interactions Between Porcine Gastric Mucin and Some Water-Soluble Polymers.

    PubMed

    Albarkah, Yasser A; Green, Rebecca J; Khutoryanskiy, Vitaliy V

    2015-11-01

    This study investigates the structural features of porcine gastric mucin (PGM) in aqueous dispersions and its interactions with water-soluble polymers (poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(ethylene oxide), and poly(ethylene glycol)) using isothermal titration calorimetry, turbidimetric titration, dynamic light scattering, and transmission electron microscopy. It is established that PAA (450 kDa) and PMAA (100 kDa) exhibit strong specific interactions with PGM causing further aggregation of its particles, while PAA (2 kDa), poly(ethylene oxide) (1 000 kDa), and poly(ethylene glycol) (10 kDa) do not show any detectable effects on mucin. Sonication of mucin dispersions prior to their mixing with PAA (450 kDa) and PMAA (100 kDa) leads to more pronounced intensity of interactions. PMID:26102520

  18. 15. Power copy of drawing, August 21, 1915. POWER PLANT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Power copy of drawing, August 21, 1915. POWER PLANT EXTENSION, GENERAL PLANS. Drawing No. PA-A-36692, Facilities Engineering, Army Materials Technology Laboratory, Watertown, Massachusetts. - Watertown Arsenal, Building No. 60, Arsenal Street, Watertown, Middlesex County, MA

  19. Demonstration Advanced Avionics System (DAAS), Phase 1

    NASA Technical Reports Server (NTRS)

    Bailey, A. J.; Bailey, D. G.; Gaabo, R. J.; Lahn, T. G.; Larson, J. C.; Peterson, E. M.; Schuck, J. W.; Rodgers, D. L.; Wroblewski, K. A.

    1981-01-01

    Demonstration advanced anionics system (DAAS) function description, hardware description, operational evaluation, and failure mode and effects analysis (FMEA) are provided. Projected advanced avionics system (PAAS) description, reliability analysis, cost analysis, maintainability analysis, and modularity analysis are discussed.

  20. Determination of primary aromatic amines in cold water extract of coloured paper napkin samples by liquid chromatography-tandem mass spectrometry.

    PubMed

    Yavuz, Oguzhan; Valzacchi, Sandro; Hoekstra, Eddo; Simoneau, Catherine

    2016-06-01

    The aim of this study was the optimisation of a multi-analyte method for the analysis of primary aromatic amines (PAAs) from napkins in order to support official controls and food safety. We developed a UHPLC-MS/MS method for the simultaneous determination of 36 toxicologically relevant PAAs for paper and board. Good regression coefficients of the calibration curves in a range of 0.992-0.999 and reproducibilities in a range of 2.3-15% were obtained. Limits of detections (LODs) were in the range of 0.03-1.4 µg l(-1) and recoveries were in a range of 21-110% for all the amines. A total of 93 coloured paper napkin samples from different European countries were bought and extracted with water to determine the PAAs. The results showed that 42 of 93 samples contained at least one PAA. More than half of the detected PAAs are considered as toxic, carcinogenic or probably carcinogenic to humans by the International Agency for Research on Cancer (IARC), or are classified as such in the European Union legislation on chemicals. Summed concentrations of PAAs in seven samples were higher than 10 µg l(-1), the limit of summed PAA in the European Union plastic food contact material regulation. Also, eight PAAs, classified as Category 1A and 1B carcinogen in the European Union legislation of chemicals, were detected at concentrations higher than 2 µg l(-1), exceeding the limit proposed by the Federal Institute for Risk Assessment in Germany. Aniline (n = 14) was most frequently present in higher concentrations followed by o-toluidine, o-anisidine, 2,4-dimethylaniline and 4-aminoazobenzene. Red, orange, yellow and multicoloured paper napkins contained the highest concentrations of total PAAs (> 10 µg l(-1)). Although the European Union has not harmonised the legislation of paper and board materials and, thus, there is no specific migration limit for PAAs from paper napkins, the present study showed that coloured paper napkins can contain toxic and carcinogenic PAAs at

  1. Determination of primary aromatic amines in cold water extract of coloured paper napkin samples by liquid chromatography-tandem mass spectrometry

    PubMed Central

    Yavuz, Oguzhan; Valzacchi, Sandro; Hoekstra, Eddo; Simoneau, Catherine

    2016-01-01

    ABSTRACT The aim of this study was the optimisation of a multi-analyte method for the analysis of primary aromatic amines (PAAs) from napkins in order to support official controls and food safety. We developed a UHPLC-MS/MS method for the simultaneous determination of 36 toxicologically relevant PAAs for paper and board. Good regression coefficients of the calibration curves in a range of 0.992–0.999 and reproducibilities in a range of 2.3–15% were obtained. Limits of detections (LODs) were in the range of 0.03–1.4 µg l–1 and recoveries were in a range of 21–110% for all the amines. A total of 93 coloured paper napkin samples from different European countries were bought and extracted with water to determine the PAAs. The results showed that 42 of 93 samples contained at least one PAA. More than half of the detected PAAs are considered as toxic, carcinogenic or probably carcinogenic to humans by the International Agency for Research on Cancer (IARC), or are classified as such in the European Union legislation on chemicals. Summed concentrations of PAAs in seven samples were higher than 10 µg l–1, the limit of summed PAA in the European Union plastic food contact material regulation. Also, eight PAAs, classified as Category 1A and 1B carcinogen in the European Union legislation of chemicals, were detected at concentrations higher than 2 µg l–1, exceeding the limit proposed by the Federal Institute for Risk Assessment in Germany. Aniline (n = 14) was most frequently present in higher concentrations followed by o-toluidine, o-anisidine, 2,4-dimethylaniline and 4-aminoazobenzene. Red, orange, yellow and multicoloured paper napkins contained the highest concentrations of total PAAs (> 10 µg l–1). Although the European Union has not harmonised the legislation of paper and board materials and, thus, there is no specific migration limit for PAAs from paper napkins, the present study showed that coloured paper napkins can contain toxic and

  2. Vertical Carbon Nanotube Device in Nanoporous Templates

    NASA Technical Reports Server (NTRS)

    Maschmann, Matthew Ralph (Inventor); Fisher, Timothy Scott (Inventor); Sands, Timothy (Inventor); Bashir, Rashid (Inventor)

    2014-01-01

    A modified porous anodic alumina template (PAA) containing a thin CNT catalyst layer directly embedded into the pore walls. CNT synthesis using the template selectively catalyzes SWNTs and DWNTs from the embedded catalyst layer to the top PAA surface, creating a vertical CNT channel within the pores. Subsequent processing allows for easy contact metallization and adaptable functionalization of the CNTs and template for a myriad of applications.

  3. Histological changes and antioxidant enzyme activity in signal crayfish (Pacifastacus leniusculus) associated with sub-acute peracetic acid exposure.

    PubMed

    Chupani, Latifeh; Zuskova, Eliska; Stara, Alzbeta; Velisek, Josef; Kouba, Antonin

    2016-01-01

    Peracetic acid (PAA) is a powerful disinfectant recently adopted as a therapeutic agent in aquaculture. A concentration of 10 mg L(-1) PAA effectively suppresses zoospores of Aphanomyces astaci, the agent of crayfish plague. To aid in establishing safe therapeutic guideline, the effects of PAA on treated crayfish were investigated through assessment of histological changes and oxidative damage. Adult female signal crayfish Pacifastacus leniusculus (n = 135) were exposed to 2 mg L(-1) and 10 mg L(-1) of PAA for 7 days followed by a 7 day recovery period in clean water. Superoxide dismutase activity was significantly lower in gill and hepatopancreas after three days exposure to 10 mg L(1) PAA than in the group treated with 2 mg L(-1) PAA and a control in only clean water. Catalase activity in gill and hepatopancreas remained unaffected by both exposures. Glutathione reductase was significantly decreased in gill of 10 mg L(-1) PAA treated crayfish and increased in group exposed to 2 mg L(-1) compared to control after 7 days exposure. Antioxidant enzyme activity in exposed groups returned to control values after recovery period. Gill, hepatopancreas, and antennal gland showed slight damage in crayfish treated with 2 mg L(-1) of PAA compared to the control group. The extent and frequency of histological alterations were more pronounced in animals exposed to 10 mg L(-1). The gill was the most affected organ, infiltrated by granular hemocytes and displaying malformations of lamella tips and disorganization of epithelial cells. After a 7 day recovery period, the infiltrating cells in affected tissues of the exposed crayfish began to return to normal levels. Results suggested that the given concentrations could be applied to signal crayfish against crayfish plague agent in aquaculture; however, further studies are required for safe use. PMID:26611721

  4. Polyacrylic acid attenuates ethylene glycol induced hyperoxaluric damage and prevents crystal aggregation in vitro and in vivo.

    PubMed

    Sridharan, Badrinathan; Ganesh, Rajesh Nachiappa; Viswanathan, Pragasam

    2016-05-25

    The study explores calcium oxalate crystal inhibiting characteristic of polyacrylic acid (pAA), an anionic polymer in in vitro and in vivo. Animals were divided into 5 groups where group 1 served as control, group 2 were made hyperoxaluric by supplementing with Ethylene glycol (EG) 0.75% (v/v) for 30 days. Group 3, 4 & 5 were also given with EG and treated simultaneously with 2.5, 5 & 10 mg of pAA/kg of body weight, respectively. Urine, serum and tissue analyses along with histological studies were performed at the end of the 30 days study. In vitro crystallization was significantly inhibited by pAA and further it was supported by particle size analyses, XRD and FT-IR studies. Toxicological analyses showed that pAA was safe to use in animals at concentrations below 100 mg/kg BW. In vivo anti-urolithic study showed significant improvement in urinary lithogenic factors (calcium, oxalate, phosphate, citrate & magnesium) and renal function parameters (creatinine, urea and protein). Tissue analyses on anti-oxidant enzyme activity and lipid peroxides showed maintenance of tissue antioxidant status in the pAA supplemented rats and histological studies demonstrated the nephroprotection offered by pAA and were concurrent to the biochemical analyses. Supplementation of pAA not only reduces the crystal aggregation but also regulates the expression and localization of crystal inhibiting proteins and gene expression of inflammatory cytokines in experimental animals. In summary, pAA is a potent anti-urolithic agent in rats and we can propose that 10 mg/kg body weight is the effective dosage of pAA and this concentration can be used for further studies. PMID:27018375

  5. Pulmonary Artery Aneurysm Thrombosis with Combined Pulmonary Fibrosis and Emphysema: A Case Report

    PubMed Central

    Awad, Nilkant Tukaram

    2016-01-01

    We report a rare case of Pulmonary Artery Aneurysm (PAA) thrombosis with Combined Pulmonary Fibrosis and Emphysema (CPFE) with pulmonary hypertension. A 75-year-old male presented with haemoptysis, dyspnoea, clubbing and bilateral fine end inspiratory rales on examination. He was diagnosed to have PAA thrombosis with CPFE on the basis of computed tomographical angiography and high resolution computed tomography. He was then managed conservatively with pirfenidone for the interstitial lung disease. PMID:27437277

  6. Evaluation of the toxicity data for peracetic acid in deriving occupational exposure limits: a minireview.

    PubMed

    Pechacek, Nathan; Osorio, Magdalena; Caudill, Jeff; Peterson, Bridget

    2015-02-17

    Peracetic acid (PAA) is a peroxide-based chemistry that is highly reactive and can produce strong local effects upon direct contact with the eyes, skin and respiratory tract. Given its increasing prominence in industry, attention has focused on health hazards and associated risks for PAA in the workplace. Occupational exposure limits (OEL) are one means to mitigate risks associated with chemical hazards in the workplace. A mini-review of the toxicity data for PAA was conducted in order to determine if the data were sufficient to derive health-based OELs. The available data for PAA frequently come from unpublished studies that lack sufficient study details, suffer from gaps in available information and often follow unconventional testing methodology. Despite these limitations, animal and human data suggest sensory irritation as the most sensitive endpoint associated with inhalation of PAA. Rodent RD50 data (the concentration estimated to cause a 50% depression in respiratory rate) were selected as the critical studies in deriving OELs. Based on these data, a range of 0.36-0.51mg/m(3) (0.1-0.2ppm) was calculated for a time-weighted average (TWA), and 1.2-1.7mg/m(3) (0.4-0.5ppm) as a range for a short-term exposure limit (STEL). These ranges compare favorably to other published OELs for PAA. Considering the applicable health hazards for this chemistry, a joint TWA/STEL OEL approach for PAA is deemed the most appropriate in assessing workplace exposures to PAA, and the selection of specific values within these proposed ranges represents a risk management decision. PMID:25542141

  7. Tuning the properties of ZnO, hematite, and Ag nanoparticles by adjusting the surface charge.

    PubMed

    Zhang, Jianhui; Dong, Guanjun; Thurber, Aaron; Hou, Yayi; Gu, Min; Tenne, Dmitri A; Hanna, C B; Punnoose, Alex

    2012-03-01

    A poly (acryl acid) (PAA) post-treatment method is performed to modify the surface charge of ZnO nanospheres, hematite nanocubes, and Ag nanoprisms from highly positive to very negative by adjusting the PAA concentration, to and greatly modify their photoluminescence, cytotoxicity, magnetism, and surface plasmon resonance. This method provides a general way to tune the nanoparticle properties for broad physicochemical and biological applications. PMID:22298490

  8. Self-Assembly of Charged Amphiphilic Diblock Copolymers with Insoluble Blocks of Decreasing Hydrophobicity: From Kinetically Frozen Colloids to Macrosurfactants

    SciTech Connect

    M Jacquin; P Muller; H Cottet; O Theodoly

    2011-12-31

    We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 C and 1 M.

  9. Specificity of human anti-carbohydrate IgG antibodies as probed with polyacrylamide-based glycoconjugates.

    PubMed

    Smorodin, E P; Kurtenkov, O A; Sergeyev, B L; Pazynina, G V; Bovin, N V

    2004-01-01

    The TF, Tn, and SiaTn glycotopes are frequently expressed in cancer-associated mucins. Antibodies to these glycotopes were found in human serum. A set of polyacrylamide (PAA)--based glycoconjugates was applied to the direct and competitive enzyme-linked immunosorbent assays (ELISA) to characterize the specificity of serum IgG antibodies. The anti-TF, -Tn and -SiaTn IgG were affinity purified from serum of cancer patients and characterized using PAA-conjugates and free saccharides. The anti-TF and -Tn antibodies were shown to be specific. The anti-TF IgG bound both Galbeta1-3GalNAcalpha- and Galbeta1-3GalNAcbeta-PAA, the latter was three-four times more effective inhibitor of antibody binding. The anti-Tn IgG reacted only with GalNAcalpha-PAA. The anti-SiaTn IgG cross-reacted with Tn-PAA but SiaTn-PAA was five-six times more effective inhibitor in a competitive assay. The IC50 values for PAA-conjugates with the corresponding antibodies typically ranged from 2 to 5 x 10(-8) M. The antibodies display a low specificity to mucin-type glycoconjugates in comparison with PAA-conjugates as was shown for mucins isolated from human malignant tumor tissues, ovine submaxillary mucin (OSM) and asialo-OSM. The unusual IgG-antibody specificity to GalNAcbeta and GalNAcbeta1-3GalNAcbeta ligands was found in human serum. PMID:15001840

  10. The AppScale Cloud Platform

    PubMed Central

    Krintz, Chandra

    2013-01-01

    AppScale is an open source distributed software system that implements a cloud platform as a service (PaaS). AppScale makes cloud applications easy to deploy and scale over disparate cloud fabrics, implementing a set of APIs and architecture that also makes apps portable across the services they employ. AppScale is API-compatible with Google App Engine (GAE) and thus executes GAE applications on-premise or over other cloud infrastructures, without modification. PMID:23828721