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Sample records for application au formaldehyde

  1. Formaldehyde.

    PubMed

    Pontén, Ann; Bruze, Magnus

    2015-01-01

    Formaldehyde is the American Contact Dermatitis Society Contact Allergen of the Year for 2015. The exposure is widespread, and contact allergy might be difficult to suspect in the individual dermatitis patient. The relevance of contact allergy to formaldehyde might also be difficult to evaluate. Recently, however, several studies have been performed aimed at enhancing the patch test technique and evaluating the clinical relevance of contact allergy to formaldehyde. The patch test concentration of formaldehyde has been recommended by the European Environmental Contact Dermatitis Research Group to be 2.0%, that is, the dose of 0.60 mg/cm (wt/vol) instead of 1.0%, which is the concentration previously used for the baseline series in most countries. Without causing any more irritant reactions, the patch test concentration of 2.0% detects twice as many contact allergies and enables the diagnosis of formaldehyde-allergic patients who otherwise would have been missed. The studies that underpin the decision were performed in Europe and partly in the United States. The Finn Chamber patch test system was used. The allergen dose per area was kept uniform with a micropipette. This report describes the background for routinely using formaldehyde 2.0% instead of 1.0% and for using a micropipette when applying the test solution. PMID:25581665

  2. Formaldehyde

    Integrated Risk Information System (IRIS)

    Formaldehyde ; CASRN 50 - 00 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  3. The microcapsule-type formaldehyde scavenger: the preparation and the application in urea-formaldehyde adhesives.

    PubMed

    Duan, Hongyun; Qiu, Teng; Guo, Longhai; Ye, Jun; Li, Xiaoyu

    2015-08-15

    The limitation and regulation of formaldehyde emissions (FE) now shows great importance in wood-based materials such as plywood and particle board manufactured for building and furnishing materials. The widely used formaldehyde-based adhesives are one of the main sources of FE from the wood products. In this work, a new kind of long-term effective formaldehyde scavenger in the microcapsule form was prepared by using an intra-liquid desiccation method. The characterizations of the capsule (UC) were performed including the morphologies, the yields, the loading efficiency as well as its sustained-release of urea in aqueous conditions. The prepared UC could be integrated in urea-formaldehyde resins by simply physical blending, and the mixtures were available to be applied as the adhesives for the manufacture of plywood. The bonding strength (BS) and the FE of the bonded plywood in both short (3h) and long (12 week) period were evaluated in detail. It was found that the FE profile of the plywood behaved following a duple exponential law within 12 week. The addition of UC in the adhesive can effectively depress the FE of the plywood not only in a short period after preparation but also in a long-term period during its practical application. The slow released urea would continuously suppress the emission of toxic formaldehyde in a sustained manner without obviously deteriorating on the BS of the adhesives. PMID:25855565

  4. A rapid formaldehyde assay using purpald reagent: application under periodation conditions.

    PubMed

    Quesenberry, M S; Lee, Y C

    1996-02-01

    Measurement of formaldehyde is encountered in a broad range of applications including the wine and alcohol industry and environmental pollution surveillance. In carbohydrate structural chemistry, frequent use is made of formaldehyde by periodate oxidation of terminal vicinal diols. Popular methods for the detection of formaldehyde use reagents such as chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonic acid) or acetylacetone. The chromotropic acid method requires heating of the sample under strongly acidic conditions, which is undesirable in many applications. The acetylacetone method yields a yellow color product, and is less specific and sensitive (Mimura et al., J. Hyg. Chem. 22, 39-41, 1976). The reaction of formaldehyde with Purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) works under alkaline conditions at room temperature, and the sensitivity is superior to other methods. The color development by this reagent, however, requires oxidation of the adduct with hydrogen peroxide, air oxygen, or dilute periodate. We found that low levels of periodate, commonly used to oxidize specifically terminal vicinal diols to yield formaldehyde, are compatible with color development with the Purpald reagent. We have investigated the conditions required for use of the Purpald reagent, especially in conjunction with periodate oxidation reactions. We have used the assay either in test tubes or with microplates, attaining sensitivity of as little as 1 nmol formaldehyde. PMID:8742081

  5. Thermodynamics of the formaldehyde-water and formaldehyde-ice systems for atmospheric applications.

    PubMed

    Barret, Manuel; Houdier, Stephan; Domine, Florent

    2011-01-27

    Formaldehyde (HCHO) is a species involved in numerous key atmospheric chemistry processes that can significantly impact the oxidative capacity of the atmosphere. Since gaseous HCHO is soluble in water, the water droplets of clouds and the ice crystals of snow exchange HCHO with the gas phase and the partitioning of HCHO between the air, water, and ice phases must be known to understand its chemistry. This study proposes thermodynamic formulations for the partitioning of HCHO between the gas phase and the ice and liquid water phases. A reanalysis of existing data on the vapor-liquid equilibrium has shown the inadequacy of the Henry's law formulation, and we instead propose the following equation to predict the mole fraction of HCHO in liquid water at equilibrium, X(HCHO,liq), as a function of the partial pressure P(HCHO) (Pa) and temperature T (K): X(HCHO,liq) = 1.700 × 10(-15) e((8014/T))(P(HCHO))(1.105). Given the paucity of data on the gas-ice equilibrium, the solubility of HCHO and the diffusion coefficient (D(HCHO)) in ice were measured by exposing large single ice crystals to low P(HCHO). Our recommended value for D(HCHO) over the temperature range 243-266 K is D(HCHO) = 6 × 10(-12) cm(2) s(-1). The solubility of HCHO in ice follows the relationship X(HCHO,ice) = 9.898 × 10(-13) e((4072/T))(P(HCHO))(0.803). Extrapolation of these data yields the P(HCHO) versus 1/T phase diagram for the H(2)O-HCHO system. The comparison of our results to existing data on the partitioning of HCHO between the snow and the atmosphere in the high arctic highlights the interplay between thermodynamic equilibrium and kinetics processes in natural systems. PMID:21171657

  6. Passive samplers for ambient ozone, formaldehyde and sulfur dioxide: Indoor, outdoor, and personal exposure applications

    SciTech Connect

    Grosjean, D.; Grosjean, E.

    1994-12-31

    Time-integrated measurements of air pollutants have many applications in the context of regulations pertaining to indoor air quality, outdoor (ambient) monitoring, and personal exposure assessment. For several years, the passive samplers developed at DGA have been applied to cost-effective measurements of parts per billion levels of ozone, formaldehyde and sulfur dioxide. Examples of applications will be described. These include (a) formaldehyde measurements in indoor settings including museums, public buildings and personal exposure; (b) ozone measurements indoor (museums, cultural heritage buildings) and outdoor (Class 1 Wilderness areas; air quality surveys in Europe, Canada and Latin America, long-term monitoring of ozone exposure in forests) and (c) surveys of ambient levels of sulfur dioxide in several eastern European countries.

  7. Synthesis of Fe3O4@phenol formaldehyde resin core-shell nanospheres loaded with Au nanoparticles as magnetic FRET nanoprobes for detection of thiols in living cells.

    PubMed

    Yang, Ping; Xu, Qi-Zhi; Jin, Sheng-Yu; Zhao, Yang; Lu, Yang; Xu, Xue-Wei; Yu, Shu-Hong

    2012-01-23

    A magnetic, sensitive, and selective fluorescence resonance energy transfer (FRET) probe for detection of thiols in living cells was designed and prepared. The FRET probe consists of an Fe(3)O(4) core, a green-luminescent phenol formaldehyde resin (PFR) shell, and Au nanoparticles (NPs) as FRET quenching agent on the surface of the PFR shell. The Fe(3)O(4) NPs were used as the core and coated with green-luminescent PFR nanoshells by a simple hydrothermal approach. Au NPs were then loaded onto the surface of the PFR shell by electric charge absorption between Fe(3)O(4)@PFR and Au NPs after modifying the Fe(3)O(4)@PFR nanocomposites with polymers to alter the charge of the PFR shell. Thus, a FRET probe can be designed on the basis of the quenching effect of Au NPs on the fluorescence of Fe(3)O(4)@PFR nanocomposites. This magnetic and sensitive FRET probe was used to detect three kinds of primary biological thiols (glutathione, homocysteine, and cysteine) in cells. Such a multifunctional fluorescent probe shows advantages of strong magnetism for sample separation, sensitive response for sample detection, and low toxicity without injury to cellular components. PMID:22190410

  8. Application of toxicogenomic profiling to evaluate effects of benzene and formaldehyde: from yeast to human

    PubMed Central

    McHale, Cliona M.; Smith, Martyn T.; Zhang, Luoping

    2014-01-01

    Genetic variation underlies a significant proportion of the individual variation in human susceptibility to toxicants. The primary current approaches to identify gene–environment (GxE) associations, genome-wide association studies (GWAS) and candidate gene association studies, require large exposed and control populations and an understanding of toxicity genes and pathways, respectively. This limits their application in the study of GxE associations for the leukemogens benzene and formaldehyde, whose toxicity has long been a focus of our research. As an alternative approach, we applied innovative in vitro functional genomics testing systems, including unbiased functional screening assays in yeast and a near-haploid human bone marrow cell line (KBM7). Through comparative genomic and computational analyses of the resulting data, we have identified human genes and pathways that may modulate susceptibility to benzene and formaldehyde. We have validated the roles of several genes in mammalian cell models. In populations occupationally exposed to low levels of benzene, we applied peripheral blood mononuclear cell transcriptomics and chromosome-wide aneuploidy studies (CWAS) in lymphocytes. In this review of the literature, we describe our comprehensive toxicogenomic approach and the potential mechanisms of toxicity and susceptibility genes identified for benzene and formaldehyde, as well as related studies conducted by other researchers. PMID:24571325

  9. Raman spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane for combustion applications

    NASA Astrophysics Data System (ADS)

    Magnotti, G.; KC, U.; Varghese, P. L.; Barlow, R. S.

    2015-09-01

    Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

  10. Synthesis, Characterization and Applications of New Nonmetallic Photocatalysts -- Resorcinol Formaldehyde Resin and Boron Carbon Oxynitride

    NASA Astrophysics Data System (ADS)

    Gu, Ting

    This thesis describes the synthesis, characterization and applications of two kinds of nonmetallic photocatalysts: resorcinol formaldehyde (RF) resin and boron carbon oxynitride (BCNO). Part I: Catalyst-free hydrothermal method was developed to synthesize RF resin. It started with a solution containing only resorcinol and formaldehyde. The products were characterized by transmission electron microscopy (TEM), Solid state 13C nuclear magnetic resonance (13C-NMR) spectrometer and UV-Visible absorption spectroscopy. The particle size (diameter: 100nm-4microm) of RF the spheres was controlled by changing the concentration of the reactants. With increasing particle size, visible light absorption of the product was also increased. These RF spheres could degrade Rhodamine B and generate OH radicals under visible light irradiation. Besides, highly concentrated starting reactants would form large macroporous gel instead of individual particles. This kind of gel could be easily shaped to dishes and tubes, which could be used in filtration and degradation of air pollutants. Part II: The BCNO was prepared by heating a mixture of boric acid, melamine and PEG in atmosphere. The optical properties of the products were measured by UV-Visible absorption spectroscopy with integrating sphere. The X-ray powder diffraction (XRD) patterns indicated that all BCNO compounds had the turbostratic boron nitride (t-BN) structure. Meanwhile, X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrum (EELS) were used to determine the chemical composition of the catalyst. The BCNO could be identified as t-BN with N atoms partly substituted by O and C atoms. The degree of substitution affected its photocatalytic properties. Perdew--Burke--Ernzerhof (PBE) exchange model was introduced to simulate the density of state (DOS) of BCNO using these supercells. Simulation results indicated that C and O substitution induced occupied impurity states in the gap region which modified the band

  11. Fe/Au Core-Shell Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Sra, Amandeep; Leslie-Pelecky, Diandra

    2009-10-01

    The physical properties of nanoparticles, including size, composition and surface chemistry, greatly influence biological and pharmacological properties and, ultimately, their clinical applications. Superparamagnetic iron oxide nanoparticles are widely used for applications such as MRI contrast agents, drug delivery via magnetic targeting and hyperthermia due to their chemical stability and biocompatibility; however, enhancing the saturation magnetization (Ms) of nanoparticles would produce greater sensitivity. Our design strategy involves a bottom-up wet chemistry approach to the synthesis of Fe nanoparticles. Specific advantages of Fe are the high value of Ms (210 emu/g in bulk) coupled with low toxicity; however, Fe nanoparticles must be protected from oxidation, which causes a dramatic reduction in Ms. To circumvent oxidation, Fe nanoparticles are coated with a Au shell that prevents the oxidation of the magnetic core and also provides the nanoparticles with plasmonic properties for optical stimulation. Ligands of various functionalities can be introduced through the well established Au-thiol surface chemistry for different biomedical applications while maintaining the magnetic functionality of the Fe core. In this presentation, we will discuss the physical, chemical and magnetic properties of our Fe/Au nanoparticles and their resistance to oxidation.

  12. Bright, NIR-emitting Au23 from Au25: characterization and applications including biolabeling.

    PubMed

    Muhammed, Madathumpady Abubaker Habeeb; Verma, Pramod Kumar; Pal, Samir Kumar; Kumar, R C Arun; Paul, Soumya; Omkumar, Ramakrishnapillai Vyomakesannair; Pradeep, Thalappil

    2009-10-01

    A novel interfacial route has been developed for the synthesis of a bright-red-emitting new subnanocluster, Au(23), by the core etching of a widely explored and more stable cluster, Au(25)SG(18) (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au(22) and Au(33). Whereas Au(22) and Au(23) are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au(33) is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au(23) exhibits quenching of fluorescence selectively in the presence of Cu(2+) ions and it can therefore be used as a metal-ion sensor. Aqueous- to organic-phase transfer of Au(23) has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au(23) before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au(23) emission has been demonstrated. The inherent fluorescence of Au(23) was used for imaging human hepatoma cells by employing the avidin-biotin interaction. PMID:19711391

  13. 29 CFR 1915.1048 - Formaldehyde.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Formaldehyde. 1915.1048 Section 1915.1048 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Formaldehyde. Note: The requirements applicable to shipyard employment under this section are identical...

  14. 29 CFR 1915.1048 - Formaldehyde.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Formaldehyde. 1915.1048 Section 1915.1048 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Formaldehyde. Note: The requirements applicable to shipyard employment under this section are identical...

  15. 29 CFR 1915.1048 - Formaldehyde.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Formaldehyde. 1915.1048 Section 1915.1048 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Formaldehyde. Note: The requirements applicable to shipyard employment under this section are identical...

  16. 29 CFR 1915.1048 - Formaldehyde.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Formaldehyde. 1915.1048 Section 1915.1048 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Formaldehyde. Note: The requirements applicable to shipyard employment under this section are identical...

  17. 29 CFR 1915.1048 - Formaldehyde.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Formaldehyde. 1915.1048 Section 1915.1048 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Formaldehyde. Note: The requirements applicable to shipyard employment under this section are identical...

  18. New formaldehyde base disinfectants.

    NASA Technical Reports Server (NTRS)

    Trujillo, R.; Lindell, K. F.

    1973-01-01

    Preparations of formaldehyde in various organic liquids - ethylene glycol, glycerol, and propylene glycol - serve as effective disinfectants towards microbial vegetative cells and spores. This disinfection is a temperature-dependent process and is manifest when these formaldehyde base disinfectants are dissolved in water. The irritating vapors associated with formaldehyde disinfection are not present in either of these new formaldehyde base disinfectants or in aqueous solutions of them.

  19. A method for treating wastewater containing formaldehyde.

    PubMed

    Lotfy, Hesham R; Rashed, I G

    2002-02-01

    Many industrial activities utilise formaldehyde as a key chemical in organic synthesis including: synthesis of special chemicals such as pentaerythritol and ethylene glycol, synthetic resins, paper products, medicinal products and drugs and others, too numerous to mention. Therefore, effluents arising from these applications may contain significant amounts of formaldehyde. In a biodegradation experiments of a wastewater sample containing formaldehyde ranging from 31.5 to 125 mg/l, residual formalin (a solution of formaldehyde gas in water) ranging from 40% to 85%, respectively, was found at the end of the run (16 d) showing the inhibition effect of formalin which increased with the increase in formalin concentration. The biodegradation of formalin decreased significantly at concentrations higher than 300 mg/l. A method to convert formaldehyde to an easily biodegradable substance is herein described. In the commercial manufacture of resins from phenol and formalin the reaction is never completely quantitative. As a result during the dehydration stage phenol and formalin are distilled from the wastewater. Phenol is toxic to several biochemical reactions. However, biological transformation of phenol to a non-toxic entity is possible through specialized microbes. Transformation of phenol is inhibited by the presence of formaldehyde. Biotransformation of phenol in a wastewater containing high concentrations of formaldehyde started shortly after treating the wastewater with calculated amounts of sodium sulphite. Sodium sulphite is believed to react with formaldehyde forming sodium formaldehyde bisulphite, which is not only non-toxic to microorganisms but also a biodegradable substance. From the DO measurements before and after the addition of sodium sulphite, the authors noticed that the dissolved oxygen in a wastewater containing formaldehyde is not affected by the addition of the calculated amount of sodium sulphite, which is just enough to consume the measured amount

  20. Shape-controlled synthesis of Au-Pd bimetallic nanocrystals for catalytic applications.

    PubMed

    Zhang, Lei; Xie, Zhaoxiong; Gong, Jinlong

    2016-07-21

    Au-Pd nanostructured materials have been recognized as important heterogeneous catalysts in various reactions, due to their superior activities caused by the ensemble and ligand effects. In recent years, shape-controlled synthesis of noble metal nanocrystals (NCs) provided a brand-new insight for improving the performance of catalysts. The electronic properties and catalytic activities of Au-Pd NCs could be optimized by tuning their shape and composition engineering. This review describes recent progress in the design and synthesis of shape-controlled Au-Pd bimetallic NCs and their emerging catalytic applications. The review starts with a general discussion of various applications of Au-Pd catalysts and the significance of preparing shape-controlled Au-Pd NCs, followed by an overview of synthetic strategies for two different structures of Au-Pd bimetallic catalysts: a core-shell structure and an alloy structure. We also put forward the key factors for the preparation of Au-Pd core-shell and alloy structures. Additionally, we discussed the unique optical properties and structural effects of shape-controlled Au-Pd NCs. These recent advancements in the methodology development of Au-Pd bimetallic NCs offer numerous insights for generating Au-Pd NCs with a number of unique geometries in the future. Furthermore, the systematic synthesis of core-shell or alloy structures would provide insights for the preparation of other bimetallic NCs. PMID:27095006

  1. The characteristics of Au:VO2 nanocomposite thin film for photo-electricity applications

    NASA Astrophysics Data System (ADS)

    Zhu, Yabin; Na, Jie; He, Fan; Zhou, Yueliang

    2013-08-01

    Au nanoparticles have been fabricated on normal glass substrates using nanosphere lithography (NSL) method. Vanadium dioxide has been deposited on Au/glass by reactive radio frequency (rf) magnetron sputtering. The structure and composition were determined by X-ray diffraction and X-ray photoelectron spectroscope. Electrical and optical properties of bare VO2 and Au:VO2 nanocomposite thin films were measured. Typical hysteresis behavior and sharp phase transition were observed. Nanopartical Au could effectively reduce the transition temperature to 40 °C. The transmittance spectrum for both Au:VO2 nanocomposite thin film shows high transmittance under transition temperature and low transmittance above transition temperature. The characteristics present the Au:VO2 nanocomposite thin film can be used for applications, such as “smart window” or “laser protector”.

  2. Thermal stability of Mo/Au bilayers for TES applications

    NASA Astrophysics Data System (ADS)

    Parra-Borderías, María; Fernández-Martínez, Iván; Fàbrega, Lourdes; Camón, Agustín; Gil, Oscar; González-Arrabal, Raquel; Sesé, Javier; Costa-Krämer, José Luis; Warot-Fonrose, Bénédicte; Serin, Virginie; Briones, Fernando

    2012-09-01

    Mo/Au bilayers are among the most suitable materials to be used as transition-edge sensors (TES) in cryogenic microcalorimeters and bolometers, developed, among other fields, for space missions. For this purpose the thermal stability of TES at temperatures below 150 °C is a critical issue. We report on the dependence of functional properties (superconducting critical temperature, residual resistance and α) as well as on microstructure, chemical composition and interface quality for optimized high quality Mo/Au bilayers on annealing temperature and time. Data show that the functional properties of the bilayers remain stable at T < 150 °C, but changes in microstructure, interface quality and functional properties were observed for layers heated at T ≥ 200 °C. Microstructural and chemical composition data suggest that the measured changes in residual resistance ratio (RRR) and TC at T ≥ 200 °C are mainly due to an increase in the average Au grain size and to Au migration along the Mo grain boundaries at the Au/Mo interface. A way to stabilize the functional properties of the Mo/Au bilayers against temperature enhancements is proposed.

  3. Formaldehyde risk assessment

    EPA Science Inventory

    We would like to comment on the paper by Crump et al. (2008), ‘Sensitivity analysis of biologically motivated model for formaldehyde-induced respiratory cancer in humans’. We are authors of the formaldehyde cancer risk assessment described in Conolly et al. (2003, 2004) that is t...

  4. Optical Detection of Formaldehyde

    NASA Technical Reports Server (NTRS)

    Patty, Kira D.; Gregory, Don A.

    2008-01-01

    The potential for buildup .of formaldehyde in closed space environments poses a direct health hazard to personnel. The National Aeronautic Space Agency (NASA) has established a maximum permitted concentration of 0.04 ppm for 7 to 180 days for all space craft. Early detection is critical to ensure that formaldehyde levels do not accumulate. above these limits. New sensor technologies are needed to enable real time,in situ detection in a compact and reusable form factor. Addressing this need,research into the use of reactive fluorescent dyes which reversibly bind to formaldehyde (liquid or gas) has been conducted to support the development of a formaldehyde.sensor. In the presence of formaldehyde the dyes' characteristic fluorescence peaks shift providing the basis for an optical detection. Dye responses to formaldehyde exposure were characterized; demonstrating the optical detection of formaldehyde in under 10 seconds and down to concentrations of 0.5 ppm. To .incorporate the dye .in.an optical sensor device requires. a means of containing and manipulating the dye. Multiple form factors using two dissimilar sbstrates were considered to determine a suitable configuration. A prototype sensor was demonstrated and considerations for a field able sensor were presented. This research provides a necessary first step toward the development of a compact, reusable; real time optical formaldehyde sensor suitable for use in the U.S. space program,

  5. Melamine-formaldehyde aerogels

    DOEpatents

    Pekala, R.W.

    1992-01-14

    Organic aerogels that are transparent and essentially colorless are prepared from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porosity, ultrafine cell/pore sizes, and optical clarity. 3 figs.

  6. Formaldehyde in Our Environment.

    ERIC Educational Resources Information Center

    Ojanlatva, Ansa; Weeks, Charlie A.

    During the energy crisis of the early 1970s, there was a drive to conserve energy in every segment of society. Citizens were encouraged to insulate their homes and tighten them up to avoid loss of energy. One of the products to emerge from this crisis was urea formaldehyde foam insulation. (Urea formaldehyde is a well-known agent for preserving…

  7. Melamine-formaldehyde aerogels

    DOEpatents

    Pekala, Richard Walter

    1992-01-01

    Organic aerogels that are transparent and essentially colorless are prepa from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porsity, ultrafine cell/pore sizes, and optical clarity.

  8. The formaldehyde dilemma.

    PubMed

    Salthammer, Tunga

    2015-06-01

    The IARC's 2004 classification of formaldehyde as a human carcinogen has led to intensive discussion on scientific and regulatory levels. In June 2014, the European Union followed and classified formaldehyde as a cause of cancer. This automatically triggers consequences in terms of emission minimization and the health-related assessment of building and consumer products. On the other hand, authorities are demanding and authorizing technologies and products which can release significant quantities of formaldehyde into the atmosphere. In the outdoor environment, this particularly applies to combusting fuels. The formation of formaldehyde through photochemical smog has also been a recognized problem for years. Indoors there are various processes which can contribute to increased formaldehyde concentrations. Overall, legislation faces a dilemma: primary sources are often over-regulated while a lack of consideration of secondary sources negates the regulations' effects. PMID:25772784

  9. Microbial Formaldehyde Oxidation

    SciTech Connect

    Timothy J. Donohue

    2004-12-09

    This project analyzed how cells sense and generate energy from formaldehyde oxidation. Formaldehyde is a toxin that is produced naturally, chemically or by metabolism of a wide variety of methyl-containing compounds. Our goals are to identify how cells sense the presence of this toxic compound and determine how they generate energy and nutrients from the oxidation of formaldehyde. This research capitalizes on the role of the Rhodobacter sphaeroides glutathione dependent formaldehyde dehydrogenase (GSH FDH) in a formaldehyde oxidation pathway that is apparently found in a wide variety of microbes, plants and animals. Thus, our findings illustrate what is required for a large variety of cells to metabolize this toxic compound. A second major focus of our research is to determine how cells sense the presence of this toxic compound and control the expression of gene products required for its detoxification.

  10. Formaldehyde and skin tumorigenesis in Sencar mice

    SciTech Connect

    Iversen, O.H.

    1988-01-01

    Previous experiments involving topical applications of formaldehyde on hairless mouse skin were repeated with SENCAR mice, which are bred for maximum sensitivity to chemical tumorigenesis. Most experimental groups consisted of 32 mice. Topical skin applications of either 100 ..mu..l acetone of about 200 ..mu..l 4% formaldehyde in water twice weekly, resulted in two tumor-bearing animals, each with one small, benign papilloma. A group of 96 mice, treated once with 51.2 ..mu..g DMBA in acetone, developed a total of 107 tumors in 40 tumor-bearing animals. Thus, DMBA is a strong, complete tumorigen also in SENCAR mice. Animals given 51.2 ..mu..g DMBA first and then treated twice weekly with 1% formaldehyde developed a total of 30 tumors in 8 tumor-bearing animals, whereas mice given 51.2 ..mu..g DMBA first, followed by twice weekly treatment with 4% formaldehyde, developed 51 tumors in 15 animals. When two widely accepted, statistical methods were used, there was no significant difference between the groups treated once with DMBA alone and that treated once with DMBA followed by 4% formaldehyde. The results in SENCAR mice confirm that formaldehyde has no skin tumorigenic or carcinogenic potency of its own. It seems doubtful whether it may act as a very weak enhancer of DMBA-induced tumorigenesis, but it has no significant influence on DMBA-induced carcinogenesis.

  11. Effect of Au nanorods on potential barrier modulation in morphologically controlled Au@Cu2O core-shell nanoreactors for gas sensor applications.

    PubMed

    Majhi, Sanjit Manohar; Rai, Prabhakar; Raj, Sudarsan; Chon, Bum-Soo; Park, Kyung-Kuen; Yu, Yeon-Tae

    2014-05-28

    In this work, Au@Cu2O core-shell nanoparticles (NPs) were synthesized by simple solution route and applied for CO sensing applications. Au@Cu2O core-shell NPs were formed by the deposition of 30-60 nm Cu2O shell layer on Au nanorods (NRs) having 10-15 nm width and 40-60 nm length. The morphology of Au@Cu2O core-shell NPs was tuned from brick to spherical shape by tuning the pH of the solution. In the absence of Au NRs, cubelike Cu2O NPs having ∼200 nm diameters were formed. The sensor having Au@Cu2O core-shell layer exhibited higher CO sensitivity compared to bare Cu2O NPs layer. Tuning of morphology of Au@Cu2O core-shell NPs from brick to spherical shape significantly lowered the air resistance. Transition from p- to n-type response was observed for all devices below 150 °C. It was demonstrated that performance of sensor depends not only on the electronic sensitization of Au NRs but also on the morphology of the Au@Cu2O core-shell NPs. PMID:24779525

  12. A general analytical model for formaldehyde and VOC emission/sorption in single-layer building materials and its application in determining the characteristic parameters

    NASA Astrophysics Data System (ADS)

    Xiong, Jianyin; Liu, Cong; Zhang, Yinping

    2012-02-01

    A general analytical model for characterizing emission and sorption of formaldehyde and volatile organic compounds (VOCs) in single-layer building materials is developed. Compared with traditional models, the present model can be applicable for four kinds of typical physical processes, i.e., emission in ventilated and airtight chambers, and sorption in these two types of chambers. Based on the general analytical model, a novel method is proposed to determine the characteristic parameters (the diffusion coefficient, Dm, and the material/air partition coefficient, K) of formaldehyde and VOC sorption in ventilated and airtight chambers. It establishes a linear relationship between the logarithm of dimensionless excess concentration and sorption time, and the Dm and K can be conveniently obtained from the slope and intercept of the regression line. The results of applying the present model are compared with the experimental data in the literature. The good agreement between them not only validates the model but also demonstrates that the measured characteristic parameters are accurate and reliable. The general analytical model should prove useful for unified characterization and prediction of emission/sorption in building materials as well as for parameter measurement.

  13. Microfabricated Formaldehyde Gas Sensors

    PubMed Central

    Flueckiger, Jonas; Ko, Frank K.; Cheung, Karen C.

    2009-01-01

    Formaldehyde is a volatile organic compound that is widely used in textiles, paper, wood composites, and household materials. Formaldehyde will continuously outgas from manufactured wood products such as furniture, with adverse health effects resulting from prolonged low-level exposure. New, microfabricated sensors for formaldehyde have been developed to meet the need for portable, low-power gas detection. This paper reviews recent work including silicon microhotplates for metal oxide-based detection, enzyme-based electrochemical sensors, and nanowire-based sensors. This paper also investigates the promise of polymer-based sensors for low-temperature, low-power operation. PMID:22291561

  14. Highly selective ratiometric fluorescent probe for Au3+ and its application to bioimaging.

    PubMed

    Choi, Ji Young; Kim, Gun-Hee; Guo, Zhiqian; Lee, Hye Yeon; Swamy, K M K; Pai, Jaeyoung; Shin, Seunghoon; Shin, Injae; Yoon, Juyoung

    2013-11-15

    The 4-propargylamino-1,8-naphthalimide based fluorescent probe 1 has been explored as a sensor for selective detection of Au(3+). 4-Amino-1,8-naphthalimides, that possess typical intramolecular charge transfer (ICT) electronic characteristics, have been widely used as versatile platforms for fluorescent probes. The newly designed probe 1 contains a propargylamine moiety at C-4 of the naphthalimide chromophore that reacts with Au(3+) to generate a product that has distinctly different electronic properties from 1. Specifically, the probe undergoes a remarkable change in its absorption spectrum upon addition of Au(3+) that is associated with a distinct color change from yellow to light pink. In addition, a blue shift of ca. 56 nm also takes place in the emission spectra of the probe. Consequently, 1 serves as a reaction-based sensor or so called chemodosimeter for Au(3+). Importantly, surfactants enhance the rate of reaction of 1 with Au(3+), thus, enhancing its use as a real time sensor. Finally, the results of studies probing its application to bioimaging of Au(3+) in live cells show that the probe 1 has a unique ability to sense Au(3+) in cells and, in particular, in lipid droplets within cells. PMID:23810913

  15. Synthesis and biosensor application of Ag@Au bimetallic nanoparticles based on localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Ghodselahi, T.; Arsalani, S.; Neishaboorynejad, T.

    2014-05-01

    This work demonstrates a simple method for synthesizing gold-silver bimetallic nanoparticles (Ag@Au BNPs). Ag@Au BNPs on the carbon thin film are prepared by co-deposition of RF-sputtering and RF-PECVD using acetylene gas and gold-silver target. X-ray diffraction analysis indicates that Au and Ag NPs with FCC crystal structure are formed in our samples. From AFM image and data, average particles size of gold and silver are estimated to be about 5 and 8 nm, respectively. XRD profile and localized surface plasmon resonance (LSPR) spectroscopy indicate that Ag NPs in Ag@Au BNPs composite have a more chemical activity with respect to bare Ag NPs. Biosensor application of Ag@Au BNPs without probe immobilization is introduced too. The change in LSPR absorption peak of Ag@Au BNPs in presence of DNA primer decamer (ten-deoxycytosine) at fM concentrations is investigated. The LSPR absorption peak of Au NPs has a blue shift and the LSPR absorption peak of Ag NPs has a red shift by addition of DNA primer and under DNA exposure up to 1 h. Our sample shows a good response to low concentration of DNA and has a short response time. Both of these are prerequisite for applying this sample as LSPR biosensor chip.

  16. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. PMID:21115279

  17. Application of Cryopreserved Fibroblast Culture with Au Nanoparticles to Treat Burns.

    PubMed

    Volkova, Nataliia; Yukhta, Mariia; Pavlovich, Olena; Goltsev, Anatoliy

    2016-12-01

    The aim was to investigate a possibility of using the cryopreserved human culture of fibroblasts (CrHFC) with gold nanoparticles (AuNPs) to treat experimental burns in rats.The third-degree burns were modeled in white male rats. All the animals with burns were divided into three experimental groups: control group with no wound treatment; group 1 was composed of animals with CrHFC application; and group 2 consisted of those with CrHFC and AuNPs (6 μg/ml) application to a burn surface the next day after the injury. The CrHFC was applied to the methylcellulose gel in a dose of 5 × 10(4) of viable cells per 1 cm(2) of the burn. The animals were removed from the experiment on day 21 after the treatment.The CrHFC use alone and with AuNPs to the surface of burns stimulated the wound healing compared with the control. The effect of using CrHFC was less pronounced compared to the CrHFC application with AuNPs. It was reflected in a slower recovery of burns and moderate lymphocytic infiltration of granulation tissue. Immunofluorescent analysis emphasized that the use of CrHFC with AuNPs accelerated the skin synthetic processes and was helpful in recovering type I and III collagen content on day 21 after therapy.The results were likely related primarily to the unique structure and antimicrobial properties of AuNPs. Our experimental study of the effect of CrHFC with AuNPs application on regenerative processes in burns gives some pre-conditions to the following advanced bio- and nanotechnology developments. PMID:26762263

  18. Virus-templated Au and Au/Pt Core/shell Nanowires and Their Electrocatalytic Activitives for Fuel Cell Applications

    PubMed Central

    LEE, YOUJIN; KIM, JUNHYUNG; YUN, DONG SOO; NAM, YOON SUNG; SHAO-HORN, YANG; BELCHER, ANGELA M.

    2014-01-01

    A facile synthetic route was developed to make Au nanowires (NWs) from surfactant-mediated bio-mineralization of a genetically engineered M13 phage with specific Au binding peptides. From the selective interaction between Au binding M13 phage and Au ions in aqueous solution, Au NWs with uniform diameter were synthesized at room temperature with yields greater than 98 % without the need for size selection. The diameters of Au NWs were controlled from 10 nm to 50 nm. The Au NWs were found to be active for electrocatalytic oxidation of CO molecules for all sizes, where the activity was highly dependent on the surface facets of Au NWs. This low-temperature high yield method of preparing Au NWs was further extended to the synthesis of Au/Pt core/shell NWs with controlled coverage of Pt shell layers. Electro-catalytic studies of ethanol oxidation with different Pt loading showed enhanced activity relative to a commercial supported Pt catalyst, indicative of the dual functionality of Pt for the ethanol oxidation and Au for the anti-poisoning component of Pt. These new one-dimensional noble metal NWs with controlled compositions could facilitate the design of new alloy materials with tunable properties. PMID:24910712

  19. Effect of natural compounds on reducing formaldehyde emission from plywood

    NASA Astrophysics Data System (ADS)

    Uchiyama, Shigehisa; Matsushima, Erica; Kitao, Nahoko; Tokunaga, Hiroshi; Ando, Masanori; Otsubo, Yasufumi

    The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35 ml, the maximum exposed test surface area of 177 cm 2 and an air purge flow rate of 50 ml min -1, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4 mg m -2 h -1 at 30 °C and 15 mg m -2 h -1 at 60 °C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30 mg m -2 h -1 at 30 °C and 0.65 mg m -2 h -1 at 60 °C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270 cm wide, 60 cm deep, 250 cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130 μg m -3. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100 μg m -3. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.

  20. Development of melamine-formaldehyde resin microcapsules with low formaldehyde emission suited for seed treatment.

    PubMed

    Yuan, Huizhu; Li, Guangxing; Yang, Lijuan; Yan, Xiaojing; Yang, Daibin

    2015-04-01

    To reduce the application frequency and improve the efficacy of insecticides, melamine-formaldehyde (MF) resin microcapsules suited for seed treatment containing a mixture of fipronil and chlorpyrifos were prepared by in situ polymerization. A formaldehyde/melamine molar ratio of 4:1 yielded microcapsules with the smallest size and the most narrow size distribution. The level of unreacted formaldehyde in the microcapsule suspension increased proportionally with the F/M molar ratio. When the MF resin microcapsule suspension was used as a seed treatment to coat peanut seeds, the unreacted formaldehyde did not significantly inhibit the seedling emergence, but the ongoing release of formaldehyde generated from the degradation of MF resins played an important role in inhibiting emergence. Melamine was shown to be an effective formaldehyde scavenger that mitigated this inhibition when it was incorporated within the microcapsule wall. Field experiments showed that MF-resin-encapsulated mixtures of fipronil and chlorpyrifos have much greater efficacies against white grubs than the conventional formulation. PMID:25734968

  1. Au dotted magnetic network nanostructure and its application for on-site monitoring femtomolar level pesticide.

    PubMed

    Yang, Tianxi; Guo, Xiaoyu; Wang, Hui; Fu, Shuyue; Yu, Jie; Wen, Ying; Yang, Haifeng

    2014-04-01

    A novel magnetically responsive and surface-enhanced Raman spectroscopy (SERS) active nanocomposite is designed and prepared by direct grafting of Au nanoparticles onto the surface of magnetic network nanostructure (MNN) with the help of a nontoxic and environmentally friendly reagent of inositol hexakisphosphate shortly named as IP6. The presence of IP6 as a stabilizer and a bridging agent could weave Fe3O4 nanoparticles (NPs) into magnetic network nanostructure, which is easily dotted with Au nanoparticles (Au NPs). It has been shown firstly that the huge Raman enhancement of Au-MNN is reached by an external magnetic collection. Au-MNN presenting the large surface and high detection sensitivity enables it to exhibit multifunctional applications involving sufficient adsorption of dissolved chemical species for enrichment, separation, as well as a Raman amplifier for the analysis of trace pesticide residues at femtomolar level by a portable Raman spectrometer. Therefore, such multifunctional nanocomposites can be developed as a smart and promising nanosystem that integrates SERS approach with an easy assay for concentration by an external magnet for the effective on-site assessments of agricultural and environmental safety. PMID:24130070

  2. [Allergic contact dermatitis caused by formaldehyde and formaldehyde releasers].

    PubMed

    Latorre, N; Silvestre, J F; Monteagudo, A F

    2011-03-01

    Formaldehyde is a colorless gas with a pungent odor that is widely used as a preservative in toiletries and cosmetics and in products for household and industrial use. Both formaldehyde itself and substances that can release it are a common cause of allergic contact dermatitis. This condition often becomes chronic, given that these allergens are found nearly everywhere and it is difficult for patients to avoid them completely. This article reviews the sources of exposure to formaldehyde and formaldehyde releasers and the clinical manifestations of allergen exposure. We also review current debates and recent developments and propose guidelines for the diagnosis and treatment of patients with formaldehyde contact dermatitis. PMID:21338980

  3. Formaldehyde: an analysis of its respiratory, cutaneous, and immunologic effects

    SciTech Connect

    Bardana, E.J. Jr.; Montanaro, A. )

    1991-06-01

    Formaldehyde is truly ubiquitous in our ecology and continuing important commercial applications. Most of us have daily contact with this chemical. The most significant outdoor source of this chemical is gasoline and diesel fuel combustion. The primary indoor source is combustion of tobacco products. Formaldehyde is associated with a disagreeable odor that can produce annoyance symptoms and at higher concentrations can be a transient and completely reversible irritant to the eyes and mucous membranes of the respiratory tract. It is so soluble and rapidly metabolized that it rarely reaches the lower respiratory tract to inflict damage. The exception is in cigarette smokers who actively inhale. Formaldehyde may on rare occasions induce bronchial asthma at relatively high exposure doses. There are no conclusive studies that prove the development of de novo IgE-mediated respiratory tract symptoms secondary to inhalation of formaldehyde vapors. The approach to formaldehyde-induced symptoms should be one of careful documentation of objective physiologic changes.147 references.

  4. Formaldehyde: an analysis of its respiratory, cutaneous, and immunologic effects.

    PubMed

    Bardana, E J; Montanaro, A

    1991-06-01

    Formaldehyde is truly ubiquitous in our ecology and continuing important commercial applications. Most of us have daily contact with this chemical. The most significant outdoor source of this chemical is gasoline and diesel fuel combustion. The primary indoor source is combustion of tobacco products. Formaldehyde is associated with a disagreeable odor that can produce "annoyance" symptoms and at higher concentrations can be a transient and completely reversible irritant to the eyes and mucous membranes of the respiratory tract. It is so soluble and rapidly metabolized that it rarely reaches the lower respiratory tract to inflict damage. The exception is in cigarette smokers who actively inhale. Formaldehyde may on rare occasions induce bronchial asthma at relatively high exposure doses. There are no conclusive studies that prove the development of de novo IgE-mediated respiratory tract symptoms secondary to inhalation of formaldehyde vapors. The approach to formaldehyde-induced symptoms should be one of careful documentation of objective physiologic changes. PMID:2048760

  5. Air Mass Factor Formulation for Spectroscopic Measurements from Satellites: Application to Formaldehyde Retrievals from the Global Ozone Monitoring Experiment

    NASA Technical Reports Server (NTRS)

    Palmer, Paul I.; Jacob, Daniel J.; Chance, Kelly; Martin, Randall V.; Spurr, Robert J. D.; Kurosu, Thomas P.; Bey, Isabelle; Yantosca, Robert; Fiore, Arlene; Li, Qinbin

    2004-01-01

    We present a new formulation for the air mass factor (AMF) to convert slant column measurements of optically thin atmospheric species from space into total vertical columns. Because of atmospheric scattering, the AMF depends on the vertical distribution of the species. We formulate the AMF as the integral of the relative vertical distribution (shape factor) of the species over the depth of the atmosphere, weighted by altitude-dependent coefficients (scattering weights) computed independently from a radiative transfer model. The scattering weights are readily tabulated, and one can then obtain the AMF for any observation scene by using shape factors from a three dimensional (3-D) atmospheric chemistry model for the period of observation. This approach subsequently allows objective evaluation of the 3-D model with the observed vertical columns, since the shape factor and the vertical column in the model represent two independent pieces of information. We demonstrate the AMF method by using slant column measurements of formaldehyde at 346 nm from the Global Ozone Monitoring Experiment satellite instrument over North America during July 1996. Shape factors are cumputed with the Global Earth Observing System CHEMistry (GEOS-CHEM) global 3-D model and are checked for consistency with the few available aircraft measurements. Scattering weights increase by an order of magnitude from the surface to the upper troposphere. The AMFs are typically 20-40% less over continents than over the oceans and are approximately half the values calculated in the absence of scattering. Model-induced errors in the AMF are estimated to be approximately 10%. The GEOS-CHEM model captures 50% and 60% of the variances in the observed slant and vertical columns, respectively. Comparison of the simulated and observed vertical columns allows assessment of model bias.

  6. Green synthesis and applications of Au-Ag bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Meena Kumari, M.; Jacob, John; Philip, Daizy

    2015-02-01

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenol < k2-nitrophenol < k3-nitrophenol. Thermal conductivity is measured as a function of volume fraction and it is observed that the incorporation of the alloy nanoparticles enhances the thermal conductivity of the base fluid (water) showing nanofluid application. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field.

  7. Green synthesis and applications of Au-Ag bimetallic nanoparticles.

    PubMed

    Meena Kumari, M; Jacob, John; Philip, Daizy

    2015-02-25

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenolapplication. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field. PMID:25218228

  8. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications

    NASA Astrophysics Data System (ADS)

    Muñoz-Noval, Alvaro; Rubio-Zuazo, Juan; Salas-Colera, Eduardo; Serrano, Aida; Rubio-Marcos, Fernando; Castro, Germán R.

    2015-11-01

    The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.

  9. Colloidal Au-enhanced surface plasmon resonance imaging: application in a DNA hybridization process

    NASA Astrophysics Data System (ADS)

    Manera, M. G.; Spadavecchia, J.; Taurino, A.; Rella, R.

    2010-03-01

    The detection of the DNA hybridization mechanism using monodispersed gold nanoparticles as labels is an interesting alternative to increase the sensitivity of the SPR imaging technique. DNA-modified Au nanoparticles (DNA-Au NPs) containing single-stranded (ss) portions of DNA were prepared by monitoring their monolayer formation by UV-vis spectroscopy. The hybridization process between specific thio-oligonucleotides immobilized on the DNA-Au NPs and the corresponding complementary strands is reported and compared with the traditional hybridization process on properly self-assembled thin gold films deposited on glass substrates. A remarkable signal amplification is observed, following the incorporation of colloidal Au into a SPR biosensing experiment, resulting in an increased SPR response to DNA-DNA interactions. In particular Fusarium thiolated DNA (5'HS poly(T)15ATC CCT CAA AAA CTG CCG CT-3) and trichothecenes complementary DNA (5'-AGC GGC AGT TTT TGA GGG AT-3') sequences have been explored due to their possible application to agro-industry for the control of food quality.

  10. Au/(Ti-W) and Au/Cr metallization of chemically vapor-deposited diamond substrates for multichip module applications

    NASA Astrophysics Data System (ADS)

    Meyyappan, Ilango; Malshe, A. P.; Naseem, H. A.; Brown, W. D.

    1994-12-01

    Since diamond obtained by chemical vapor deposition (CVD) has an extremely high thermal conductivity, it holds great promise in solving thermal management problems in high performance multichip modules (MCMs). Consequently, there is a need to develop a reliable metallization system for CVD diamond. Refractory metals such as Ti, Mo, Ta and W are known to form adhering carbide layers at high temperatures. Also, transition metals such as Cr, Ni and Ni-Cr are widely used in other MCM technologies involving Si, AlN, SiC and alumina substrates. In the work reported here, adherent Au/Cr and Au/(Ti-W) metallization systems were produced at low temperatures using d.c. magnetron sputtering and electron beam evaporation techniques. Adhesion at low temperature is essential since CVD diamond could lose its thermal and electrical properties at high temperatures. Furthermore, interaction between metal layers may cause an increase in conductor trace resistivity and delamination. Adhesion was measured using a Sebastian V-A thin film stud pull tester. The deposition parameters were optimized to give maximum adhesion using a statistical design software package, echip. In the case of the sputtered metallization, pre-sputter cleaning of diamond surface improved adhesion significantly. Values above 9 klbf/sq in were obtained in the case of Au/(Ti-W) and 11.8 klbf/sq in in the case of Au/Cr. Post-deposition annealing was performed in nitrogen ambient to investigate the effect of post-metallization processing on adhesion and also to test for any possible interaction between the metals at high temperatures. Annealing temperatures were limited to 450 C since MCM substrates are seldom exposed to temperatures higher than these. Energy-dispersive spectroscopy (EDS) analysis indicated outdiffusion of W through Au at 400 deg C. No interdiffusion was observed in the case of Au/Cr as per optical microscopy and EDS analysis. Auger electron spectroscopy results indicate interaction between the

  11. High Resolution Formaldehyde Photochemistry

    NASA Astrophysics Data System (ADS)

    Ernest, C. T.; Bauer, D.; Hynes, A. J.

    2010-12-01

    Formaldehyde (HCHO) is the most abundant and most important organic carbonyl compound in the atmosphere. The sources of formaldehyde are the oxidation of methane, isoprene, acetone, and other volatile organic compounds (VOCs); fossil fuel combustion; and biomass burning. The dominant loss mechanism for formaldehyde is photolysis which occurs via two pathways: (R1) HCHO + hv → HCO + H (R2) HCHO + hv → H2 + CO The first pathway (R1) is referred to as the radical channel, while the second pathway (R2) is referred to as the molecular channel. The products of both pathways play a significant role in atmospheric chemistry. The CO that is produced in the molecular channel undergoes further oxidation to produce CO2. Under atmospheric conditions, the H atom and formyl radical that are produced in the radical channel undergo rapid reactions with O2 to produce the hydroperoxyl radical (HO2) via (R3) and (R4). (R3) HCO + O2 → HO2 + CO (R4) H + O2 → HO2 Thus, for every photon absorbed, the photolysis of formaldehyde can contribute one CO2 molecule to the global greenhouse budget or two HO2 radicals to the tropospheric HOx (OH + HO2) cycle. The HO2 radicals produced during formaldehyde photolysis have also been implicated in the formation of photochemical smog. The HO2 radicals act as radical chain carriers and convert NO to NO2, which ultimately results in the catalytic production of O3. Constraining the yield of HO2 produced via HCHO photolysis is essential for improving tropospheric chemistry models. In this study, both the absorption cross section and the quantum yield of the radical channel (R1) were measured at high resolution over the tropospherically relevant wavelength range 304-330 nm. For the cross section measurements a narrow linewidth Nd:YAG pumped dye laser was used with a multi-pass cell. Partial pressures of HCHO were kept below 0.3 torr. Simultaneous measurement of OH LIF in a flame allowed absolute calibration of the wavelength scale. Pressure

  12. Synthesis, characterization and application of Au-198 nanoparticles as radiotracer for industrial applications.

    PubMed

    Goswami, Sunil; Pant, H J; Biswal, Jayashree; Samantray, J S; Sharma, V K; Dash, Ashutosh

    2016-05-01

    This paper describes synthesis and characterization of radioactive gold nanoparticles ((198)Au-NPs), and explores their utility as a radiotracer for tracing an aqueous phase in a continuous laboratory-scale bubble column at ambient conditions. The performance of the (198)Au-NPs as a radiotracer was compared with the results obtained with a conventional radiotracer i.e. bromine-82 ((82)Br) as ammonium bromide and found to be identical. A tank-in-series with backmixing model (TISBM) was used to simulate the RTDs of the aqueous phase and characterize flow in the bubble column. PMID:26897465

  13. Mo6S3I6-Au composites: synthesis, conductance, and applications.

    PubMed

    Zhang, Renyun; Hummelgård, Magnus; Dvorsek, Damjan; Mihailovic, Dragan; Olin, Håkan

    2010-08-15

    A single-step, premixing method was used to directly deposit gold nanoparticles on Mo(6)S(3)I(6) (MSI) molecular wire bundles. Gold nanoparticles with different sizes and densities were coated on the MSI by changing the concentration of the gold containing salt, HAuCl(4). TEM, SEM, and EDX characterization showed deposition of gold nanoparticles on the MSI nanowire surface. The electrical resistance of these MSI-Au composites was more than 100 times lower than that for pure MSI, and was mainly dependent on the density of the deposited gold nanoparticles. Furthermore, we immobilized thiol group-labeled oligonucleotide on the composites and then hybridized with a fully matched sequence. The resistance of the MSI-Au composites increased during the thiol step, while it decreased by hybridizing, due to the conductance difference between single- and double-stranded DNA chains. These results indicate that this new kind of MSI-Au composite could be used as a platform for different applications, including biosensors. PMID:20494366

  14. Ionic liquid functionalized graphene/Au nanocomposites and its application for electrochemical immunosensor.

    PubMed

    Liu, Na; Chen, Xia; Ma, Zhanfang

    2013-10-15

    In this work, a new nanocomposite, which was composed of ionic liquid functionalized graphene sheet (IL-GS) loaded gold nanoparticles (AuNPs), was prepared. The IL-GS was directly synthesized by the electrochemical exfoliation of graphite in ionic liquid (IL). Due to the modification of the IL, IL-GS can not only be dispersed easily in aqueous solution to form a homogeneous colloidal suspension of individual sheet, but also exhibits an improved conductivity. Meanwhile, the loaded AuNPs on the nanocomposites can increase the specific surface area to capture a large amount of antibodies as well as improve the capability of electron transfer. The IL-GS-Au nanocomposites were successfully employed for the fabrication of a facile and sensitive electrochemical immunosensor. Carcinoembryonic antigen (CEA) was used as a model protein. The proposed immunosensor exhibits a wide linear detection range (LDR) from 1 fg mL⁻¹ to 100 ng mL⁻¹, and an ultralow limit of detection (LOD) of 0.1 fg mL⁻¹ (S/N=3). In addition, for the detection of clinical serum samples, it is well consistent with the data determined by the developed immunoassay and ELISA, indicating that the immunosensor provides a possible application for the detection of CEA in clinical diagnostics. PMID:23644143

  15. Ellagic Acid Directed Growth of Au-Pt Bimetallic Nanoparticles and Their Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Barnaby, Stacey N.; Sarker, Nazmul H.; Banerjee, Ipsita A.

    2013-02-01

    In this work, we report the facile formation of bimetallic nanoparticles of Au-Pt in the presence of the plant polyphenol ellagic acid (EA). It was found that EA formed micro-fibrillar assemblies, which aggregated into micro-bundles under aqueous conditions. Those micro-bundles acted as templates for the growth of Au nanoparticles, as well as bimetallic Au-Pt nanoparticles biomimetically. At higher concentrations of EA, it was observed that in addition to forming fibrous micro-bundles, columnar assemblies of EA were formed in the presence of the metal nanoparticles. The formation of the assemblies was found to be concentration dependent. It appears that upon binding to metal ions and subsequent formation of the nanoparticles, morphological changes occur in the case of EA assemblies. The morphological changes observed were probed by electron microscopy. Further, the ability of the materials to degrade the toxic aromatic nitro compound 2-methoxy-4-nitroaniline was explored, where 50% degradation was observed within 15 min, indicating that such hybrid materials may have potential applications in environmental remediation.

  16. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    PubMed

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future. PMID:25137194

  17. Catalytic process for formaldehyde oxidation

    NASA Technical Reports Server (NTRS)

    Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); D'Ambrosia, Christine M. (Inventor)

    1996-01-01

    Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

  18. Sporostatic and sporocidal properties of aqueous formaldehyde.

    NASA Technical Reports Server (NTRS)

    Trujillo, R.; David, T. J.

    1972-01-01

    Aqueous formaldehyde is shown to exert both sporostatic and sporocidal effects on Bacillus subtilis spores. The sporostatic effect is a result of the reversible inhibition of spore germination occasioned by aqueous formaldehyde; the sporocidal effect is due to the temperature-dependent inactivation of these spores in aqueous formaldehyde. The physicochemical state of formaldehyde in solution provides a framework with which to interpret both the sporostatic and sporocidal properties of aqueous formaldehyde.

  19. Photoabsorption in formaldehyde

    NASA Technical Reports Server (NTRS)

    Langhoff, P. W.; Langhoff, S. R.; Corcoran, C. T.

    1977-01-01

    Theoretical studies of the vertical electronic dipole excitation and ionization spectra in molecular formaldehyde are reported. The investigations relied on configuration-interaction calculations and moment-theory techniques. A double-zeta basis of contracted Gaussian-lobe functions supplemented with appropriate polarization and bond functions was used to construct Fock spectra in C(2 nu) symmetry for certain states near the ground state equilibrium geometry. The ionization energies, discrete vertical transition frequencies, and oscillator strengths for occupied and vertical Fock orbitals are in general accord with experimental determinations and other theoretical calculations. Stieltjes and Chebyshev vertical electronic photoionization profiles were calculated and found to be in good agreement with appropriately averaged photoionization-mass spectrometric measurements of the cross section for parent H2CO(+) ion production.

  20. Synthesis of a water-soluble thiourea-formaldehyde (WTF) resin and its application to immobilize the heavy metal in MSWI fly ash.

    PubMed

    Liu, She-Jiang; Guo, Yu-Peng; Yang, Hong-Yang; Wang, Shen; Ding, Hui; Qi, Yun

    2016-11-01

    Because of the high concentrations of heavy metals, municipal solid waste incineration (MSWI) fly ash is classified as a hazardous waste, which need to be treated to avoid damaging the environment. A novel water-soluble thiourea-formaldehyde (WTF) resin was synthesized by two step reactions (hydroxymethylation reaction and condensation reaction) in the laboratory. Synthetic conditions, removal of free formaldehyde in the resin and the ability of immobilization heavy metals in the MSWI fly ash were studied. The possible molecular structure of the resin was also discussed by elemental analysis and FTIR spectra. Experimental results showed that the synthesis conditions of WTF resin were the formaldehyde/thiourea (T/F) mole ratio of 2.5:1, hydroxymethylation at pH 7.0-8.0 and 60 °C for 30min, and condensation of at pH 4.5-5.0 and 80 °C. In addition, the end point of condensation reaction was measured by turbidity point method. The result of elemental analysis and FTIR spectra indicated that thiourea functional group in the WTF resin chelated the heavy metal ions. Melamine can efficiently reduce the free formaldehyde content in the resin from 8.5% to 2%. The leaching test showed that the immobilization rates of Cr, Pb and Cd were 96.5%, 92.0% and 85.8%, respectively. Leaching concentrations of Cr, Pb and Cd in the treated fly ash were decreased to 0.08 mg/L, 2.44 mg/L and 0.23 mg/L, respectively. The MSWI fly ash treated by WTF resin has no harm to the environment. PMID:27497309

  1. Genotoxic effects in occupational exposure to formaldehyde: A study in anatomy and pathology laboratories and formaldehyde-resins production

    PubMed Central

    2010-01-01

    Background According to the Report on Carcinogens, formaldehyde ranks 25th in the overall U.S. chemical production, with more than 5 million tons produced each year. Given its economic importance and widespread use, many people are exposed to formaldehyde environmentally and/or occupationally. Presently, the International Agency for Research on Cancer classifies formaldehyde as carcinogenic to humans (Group 1), based on sufficient evidence in humans and in experimental animals. Manyfold in vitro studies clearly indicated that formaldehyde can induce genotoxic effects in proliferating cultured mammalian cells. Furthermore, some in vivo studies have found changes in epithelial cells and in peripheral blood lymphocytes related to formaldehyde exposure. Methods A study was carried out in Portugal, using 80 workers occupationally exposed to formaldehyde vapours: 30 workers from formaldehyde and formaldehyde-based resins production factory and 50 from 10 pathology and anatomy laboratories. A control group of 85 non-exposed subjects was considered. Exposure assessment was performed by applying simultaneously two techniques of air monitoring: NIOSH Method 2541 and Photo Ionization Detection equipment with simultaneously video recording. Evaluation of genotoxic effects was performed by application of micronucleus test in exfoliated epithelial cells from buccal mucosa and peripheral blood lymphocytes. Results Time-weighted average concentrations not exceeded the reference value (0.75 ppm) in the two occupational settings studied. Ceiling concentrations, on the other hand, were higher than reference value (0.3 ppm) in both. The frequency of micronucleus in peripheral blood lymphocytes and in epithelial cells was significantly higher in both exposed groups than in the control group (p < 0.001). Moreover, the frequency of micronucleus in peripheral blood lymphocytes was significantly higher in the laboratories group than in the factory workers (p < 0.05). A moderate positive

  2. Nanocomposite of Au Nanoparticles/Helical Carbon Nanofibers and Application in Hydrogen Peroxide Biosensor.

    PubMed

    Zhai, Mumu; Cui, Rongjing; Gu, Ning; Zhang, Genhua; Lin, Wang; Yu, Lingjun

    2015-06-01

    A combined sol-gel/hydrogen reduction method has been developed for the mass production of helical carbon nanofibers (HCNFs) by the pyrolysis of acetylene at 425 degrees C in the presence of NiO nanoparticles. The synthesized HCNFs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The helical-structured carbon nanofibers have a large specific surface area and excellent biocompatibility. A novel enzymatic hydrogen peroxide sensor was then successfully fabricated based on the nanocomposites containing HCNFs and gold nanoparticles (AuNPs). The results indicated that the Au/HCNFs nanocomposites exhibited excellent electrocatalytic activity to the reduction of H2O2, offering a wide linear range from 1.0 μM to 3157 μM with a detection limit as low as 0.46 μM. The apparent Michaelis-Menten constant of the biosensor was 0.61 mM. The as-fabricated biosensor showed a rapid and sensitive amperometric response to hydrogen peroxide with acceptable preparation reproducibility and excellent stability. Because of their low cost and high stability, these novel HCNFs represent seem to be a kind of promising biomaterial and may find wide new applications in scopes such as biocatalysis, immunoassay, environmental monitoring and so on. PMID:26369097

  3. Visualization of Molecular Orbitals: Formaldehyde

    ERIC Educational Resources Information Center

    Olcott, Richard J.

    1972-01-01

    Describes a computer program that plots a solid" representation of molecular orbital charge density which can be used to analyze wave functions of molecules. Illustrated with diagrams for formaldehyde. (AL)

  4. Formaldehyde Gas Sensors: A Review

    PubMed Central

    Chung, Po-Ren; Tzeng, Chun-Ta; Ke, Ming-Tsun; Lee, Chia-Yen

    2013-01-01

    Many methods based on spectrophotometric, fluorometric, piezoresistive, amperometric or conductive measurements have been proposed for detecting the concentration of formaldehyde in air. However, conventional formaldehyde measurement systems are bulky and expensive and require the services of highly-trained operators. Accordingly, the emergence of sophisticated technologies in recent years has prompted the development of many microscale gaseous formaldehyde detection systems. Besides their compact size, such devices have many other advantages over their macroscale counterparts, including a real-time response, a more straightforward operation, lower power consumption, and the potential for low-cost batch production. This paper commences by providing a high level overview of the formaldehyde gas sensing field and then describes some of the more significant real-time sensors presented in the literature over the past 10 years or so. PMID:23549368

  5. Preparation of Ag/Au bimetallic nanostructures and their application in surface-enhanced fluorescence.

    PubMed

    Dong, Jun; Ye, Yanyan; Zhang, Wenhui; Ren, Zebin; Huo, Yiping; Zheng, Hairong

    2015-11-01

    An effective substrate for surface-enhanced fluorescence, which consists of cluster Ag/Au bimetallic nanostructures on a copper surface, was synthesized via a multi-stage galvanic replacement reaction of a Ag cluster in a chlorauric acid (HAuCl4) solution at room temperature. The fabricated silver/gold bimetallic cluster were found to yield large surface-enhanced fluorescence (SEF) enhancement factors for rhodamine 6G probe molecules deposited on the substrate, and also the fluorescence efficiency is critically dependent on the period of nanostructure growth. With the help of proper control reaction conditions, such as the reaction time, and concentration of reaction solutions, the maximum fluorescence enhanced effect was obtained. Therefore, the bimetallic nanostructure substrate also can be adapted to studies in SEF, which will expand the application of SEF. PMID:25691287

  6. Does formaldehyde induce aneuploidy?

    PubMed

    Speit, Günter; Kühner, Stefanie; Linsenmeyer, Regina; Schütz, Petra

    2011-11-01

    Formaldehyde (FA) was tested for a potential aneugenic activity in mammalian cells. We employed tests to discriminate between aneugenic and clastogenic effects in accordance with international guidelines for genotoxicity testing. The cytokinesis-block micronucleus test (CBMNT) in combination with fluorescence in situ hybridisation (FISH) with a pan-centromeric probe was performed with cultured human lymphocytes and the human A549 lung cell line. FA induced micronuclei (MN) in binuclear cells of both cell types under standard in vitro test conditions following the OECD guideline 487. FISH analysis revealed that the vast majority of induced MN were centromere negative, thus indicating a clastogenic effect. A similar result was obtained for MN induced by γ-irradiation, whereas the typical aneugens colcemid (COL) and vincristine (VCR) predominantly induced centromere-positive MN. Furthermore, COL and VCR clearly enhanced the MN frequency in mononuclear lymphocytes in the CBMNT, whereas such an effect was not observed for γ-irradiation and FA. In experiments with the Chinese hamster V79 cell line, the aneugens COL and VCR clearly increased the frequency of tetraploid second division metaphases, whereas FA did not cause such an effect. Altogether, our results confirm the clastogenicity of FA in cultured mammalian cells but exclude a significant aneugenic activity. PMID:21804075

  7. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application

    NASA Astrophysics Data System (ADS)

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-01

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S(&z.dbd;O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process.We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent

  8. Pd-on-Au Supra-nanostructures Decorated Graphene Oxide: An Advanced Electrocatalyst for Fuel Cell Application.

    PubMed

    Tao, Yingzhou; Dandapat, Anirban; Chen, Liming; Huang, Youju; Sasson, Yoel; Lin, Zhenyu; Zhang, Jiawei; Guo, Longhua; Chen, Tao

    2016-08-30

    We report a very easy and effective approach for synthesizing unique palladium-on-gold supra-nanostructure (Au@Pd-SprNS)-decorated graphene oxide (GO) nanosheets. The SprNSs comprising Au nanorods as core and a unique close-packed assembly of tiny anisotropic Pd nanoparticles (NPs) as shell were homogeneously distributed on the GO surface via electrostatic self-assembly. Compared with the traditional one-pot method for synthesis of metal NPs on GO sheets, the size and shape of core-shell Au@Pd SprNSs can be finely controlled and uniformly distributed on the GO carrier. Interestingly, this Au@Pd-SprNSs/GO nanocomposite displayed high electrocatalytic activities toward the oxidation of methanol, ethanol, and formic acid, which can be attributed to the abundance of intrinsic active sites including high density of atomic steps, ledges and kinks, Au-Pd heterojunctions and cooperative action of the two metals of the SprNSs. Additionally, uniform dispersion of the SprNSs over the GO nanosheets prevent agglomeration between the SprNSs, which is of great significance to enhance the long-term stability of catalyst. This work will introduce a highly efficient Pd-based nanoelectrocatalyst to be used in fuel cell application. PMID:27482606

  9. The Mechanism of the Formaldehyde Clock Reaction.

    ERIC Educational Resources Information Center

    Burnett, M. G.

    1982-01-01

    Provides background information and problems with the formaldehyde clock reaction, including comparisons of experimental clock times reported in the literature and conditions for the reliable use of the formaldehyde clock based on a method discussed. (JN)

  10. Formaldehyde Stress Responses in Bacterial Pathogens

    PubMed Central

    Chen, Nathan H.; Djoko, Karrera Y.; Veyrier, Frédéric J.; McEwan, Alastair G.

    2016-01-01

    Formaldehyde is the simplest of all aldehydes and is highly cytotoxic. Its use and associated dangers from environmental exposure have been well documented. Detoxification systems for formaldehyde are found throughout the biological world and they are especially important in methylotrophic bacteria, which generate this compound as part of their metabolism of methanol. Formaldehyde metabolizing systems can be divided into those dependent upon pterin cofactors, sugar phosphates and those dependent upon glutathione. The more prevalent thiol-dependent formaldehyde detoxification system is found in many bacterial pathogens, almost all of which do not metabolize methane or methanol. This review describes the endogenous and exogenous sources of formaldehyde, its toxic effects and mechanisms of detoxification. The methods of formaldehyde sensing are also described with a focus on the formaldehyde responsive transcription factors HxlR, FrmR, and NmlR. Finally, the physiological relevance of detoxification systems for formaldehyde in bacterial pathogens is discussed. PMID:26973631

  11. Formaldehyde Stress Responses in Bacterial Pathogens.

    PubMed

    Chen, Nathan H; Djoko, Karrera Y; Veyrier, Frédéric J; McEwan, Alastair G

    2016-01-01

    Formaldehyde is the simplest of all aldehydes and is highly cytotoxic. Its use and associated dangers from environmental exposure have been well documented. Detoxification systems for formaldehyde are found throughout the biological world and they are especially important in methylotrophic bacteria, which generate this compound as part of their metabolism of methanol. Formaldehyde metabolizing systems can be divided into those dependent upon pterin cofactors, sugar phosphates and those dependent upon glutathione. The more prevalent thiol-dependent formaldehyde detoxification system is found in many bacterial pathogens, almost all of which do not metabolize methane or methanol. This review describes the endogenous and exogenous sources of formaldehyde, its toxic effects and mechanisms of detoxification. The methods of formaldehyde sensing are also described with a focus on the formaldehyde responsive transcription factors HxlR, FrmR, and NmlR. Finally, the physiological relevance of detoxification systems for formaldehyde in bacterial pathogens is discussed. PMID:26973631

  12. Formaldehyde exposures from tobacco smoke: a review.

    PubMed Central

    Godish, T

    1989-01-01

    Reports of formaldehyde levels in mainstream, sidestream, and environmental tobacco smoke from nine studies are reviewed. Considerable disparity exists between formaldehyde production rates determined from mainstream-sidestream studies and those reporting levels in environmental tobacco smoke. Tobacco smoke does not appear to increase vapor-phase formaldehyde levels significantly in indoor environments, but formaldehyde exposure in mainstream smoke may pose a risk of upper respiratory system cancer and increase the risk of cancer in smokers. PMID:2665532

  13. Formaldehyde reactions in dark clouds

    NASA Technical Reports Server (NTRS)

    Sen, A. D.; Anicich, V. G.; Federman, S. R.

    1992-01-01

    The low-pressure reactions of formaldehyde (H2CO) with D(+), D2(+), D3(+), and He(+) are studied by the ion-cyclotron resonance technique. These reactions are potential loss processes for formaldehyde in cores of dark interstellar clouds. The deuterated reactants represent direct analogs for protons. Rate coefficients and branching ratios of product channels have been measured. Charge transfer is observed to be the dominant reaction of H2CO with D(+), D2(+), and He(+) ions. Only the D3(+) reaction exhibits a proton-transfer channel. All reactions proceed at rate coefficients near the collision limit. Proton-deuteron exchange reactions are found to be inefficient processes in the formaldehyde system.

  14. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application.

    PubMed

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-21

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S([double bond, length as m-dash]O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process. PMID:26758553

  15. Home Is Where the Formaldehyde Is.

    ERIC Educational Resources Information Center

    Godish, Thad

    1983-01-01

    Discusses indoor air pollution in general and formaldehyde in particular, citing major sources of formaldehyde in home building materials and home furnishings. Also describes a laboratory procedure necessary to test for formaldehyde levels in the air and in materials. Includes list of equipment required. (JM)

  16. Electrical performance of Ti-ZnO-Au thin film composite structure for device application

    NASA Astrophysics Data System (ADS)

    Joshi, Priyanka; Singh, Jitendra; Das, Surajit; Desai, J. V.; Akhtar, Jamil

    2016-04-01

    Thin film layers of Au/Ti approximately 2200 Å thick and ZnO approximately 2.24 µm thick were sputtered sequentially onto silicon dioxide coated <100> Si-wafer. Conventional wisdom confirms the adhesion of gold over zinc oxide (ZnO) by an intermediate layer of titanium for better adhesion. But, in Au/Ti/ZnO/Au/Ti structure, it was observed that with the passing of time the gold diffused into ZnO thin film at room temperature, making a very low resistance between the two gold layers eventually making a conductive path in ZnO. Therefore, electrical connectivity was found between the metal layers. A detailed experimental analysis has been carried out in support of the observed Au diffusion. In the present work, reliability of Ti/Au metallisation and anomalous electrical behavior due to gold diffusion has been studied.

  17. A Short Review on Photocatalytic Degradation of Formaldehyde.

    PubMed

    Tasbihi, Minoo; Bendyna, Joanna K; Notten, Peter H L; Hintzen, H T

    2015-09-01

    Nowadays, it is a great challenge to eliminate toxic and harmful organic pollutants from air and water. This paper reviews the role of TiO2 as a photocatalyst, light source and photoreactor in the particular case of removal of formaldehyde using the photocatalytic reaction by titanium dioxide (TiO2) in aqueous and gaseous systems. The reaction mechanisms of the photocatalytic oxidation of gaseous formaldehyde are given. We also present a detailed review of published articles on photocatalytic degradation of formaldehyde by modified titanium dioxide doped with foreign species such as metal and non-metal components. We point out the most prospective developments of the photocatalyst compositions for the future potential commercial applications. PMID:26716192

  18. Studies on adsorption of formaldehyde in zirconium phosphate-glyphosates

    NASA Astrophysics Data System (ADS)

    Zhang, Yuejuan; Yi, Jianjun; Xu, Qinghong

    2011-01-01

    In our previous work [22], a kind of layered compound of zirconium phosphate-glyphosate (ZrGP) was synthesized. Its large surface area (445 m 2/g) indicates this compound has possible application in adsorptions. In this paper, adsorption to formaldehyde in ZrGP and mechanisms of the adsorption were studied carefully. Balance time of adsorption (about 6 h) and largest adsorbed amount (7.8%) were found when adsorption temperature was at 40 °C and pH value of adsorption environment was about 3.0. H-bonds were found existing between molecules of formaldehyde and ZrGP, and formaldehyde molecules could exist in ZrGP stably.

  19. Photoionization of methanol and formaldehyde

    NASA Technical Reports Server (NTRS)

    Warneck, P.

    1971-01-01

    Photoions produced in methanol and formaldehyde by radiation in the spectral region 450-1150 A were analyzed mass spectrometrically, and their relative yields were determined as a function of wavelength. First ionization potentials were determined, and the ion yield curves were interpreted in terms of ionization processes in conjunction with other data. Fragment ions were detected on mass numbers of 31, 30, 29, 15, and 14 for methanol, and 29, 2, and 1 for formaldehyde. The associated appearance potentials were determined and were used to calculate heats of formation of the ions CH2OH(+) and HCO(+), and the radicals CH3, CH2, and HCO.

  20. Woodstoves, formaldehyde, and respiratory disease

    SciTech Connect

    Tuthill, R.W.

    1984-12-01

    Telephone interviews were completed in Western Massachusetts in April 1983 for 399 households (91.5 percent) in a random sample of households with elementary school children. Woodstoves were used in 64.7 percent of the homes, but such use was not associated with acute respiratory illness. However, formaldehyde exposure was significantly related, with a risk ratio of 2.4 (95 percent confidence interval 1.7-3.4). New construction/remodeling and new upholstered furniture had additive effects. Neither woodstove use nor formaldehyde exposure were significantly associated with asthma, chronic bronchitis, or allergies.

  1. Crystallographic investigation of Au nanoparticles embedded in a SrTiO3 thin film for plasmonics applications by means of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Pincini, Davide; Mazzoli, Claudio; Bernhardt, Hendrik; Katzer, Christian; Schmidl, Frank; Uschmann, Ingo; Detlefs, Carsten

    2015-03-01

    Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO3 matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with [ 110 ] SrTiO3 ∥ [ 110 ] Au and [ 100 ] SrTiO3 ∥ [ 110 ] Au . Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with [ 100 ] SrTiO3 ∥ [ 100 ] Au and [ 100 ] SrTiO3 ∥ [ 110 ] Au . The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.

  2. Formaldehyde in Insulation: Villain or Innocent Bystander?

    PubMed Central

    Lees, R. E. M.

    1983-01-01

    When urea formaldehyde foam insulation (UFFI) deteriorates, it produces an off-gas mixture whose major constituent is formaldehyde. Most investigative studies of UFFI have concentrated on formaldehyde. Health concerns fall into three groups: irritant characteristics, allergenic capabilities and potential carcinogenicity. Except for the first of these, formaldehyde's hazard potential is not clear. The extent to which formaldehyde may be responsible for UFFI's evil reputation is explored in this paper but the degree to which either substance is a real threat to health still appears to open to debate. PMID:21283296

  3. Controlling formaldehyde emissions with boiler ash.

    PubMed

    Cowan, Jennifer; Abu-Daabes, Malyuba; Banerjee, Sujit

    2005-07-01

    Fluidized wood ash reduces formaldehyde in air from about 20 to <1 ppmv. Methanol is removed to a much lower extent. The efficiency of formaldehyde reduction increases with increasing moisture content of the ash. Sorption of formaldehyde to ash can be substantially accounted for by partitioning to the water contained in the ash followed by rate-controlling binding to the ash solids. Adsorption occurs at temperatures of up to 165 degrees C; oxidation predominates thereafter. It is proposed that formaldehyde could be stripped from an air stream in a fluidized bed containing ash, which could then be returned to a boiler to incinerate the formaldehyde. PMID:16053116

  4. Formaldehyde monitor for automobile exhausts

    NASA Technical Reports Server (NTRS)

    Easley, W. C.

    1973-01-01

    Device makes use of microwave spectral absorption in low-Q resonant Stark cell, and indications are that ultimate sensitivity of instrument is within 100 parts per billion of formaldehyde. Microwave source is very small and requires only six-volt dc bias for operation. Coarse tuning is accomplished mechanically and fine tuning by adjusting dc-bias voltage.

  5. Report of the Federal Panel on Formaldehyde.

    PubMed Central

    1982-01-01

    The Federal Panel on Formaldehyde concluded that definitive experiments exist which demonstrate the mutagenicity and carcinogenicity of formaldehyde under laboratory conditions. Formaldehyde induces both gene mutations and chromosomal aberrations in a variety of test systems. Inhalation of formaldehyde causes cancer of the nose in rats. The concentrations of formaldehyde in inhaled air that caused nasal cancer in Fisher 344 rats are within the same order of magnitude as those to which humans may be exposed. The data presently available do not permit a direct assessment of the carcinogenicity of formaldehyde to man. Epidemiologic studies on exposed human populations are in progress and may further clarify the situation. Other experimental and human studies on toxic effects such as teratogenicity and reproductive disorders are as yet inadequate for a health risk assessment. The CIIT 24 month study on animal carcinogenicity has not yet been completely evaluated. Additional data are expected on the effects of prolonged exposure to lower doses of formaldehyde and on the possible carcinogenicity of formaldehyde in the mouse. The panel recommends that, for a comprehensive health risk assessment, further experiments be conducted on the effects of other modes of exposure (ingestion and skin penetration), the effects in humans, and on the pharmacokinetics of formaldehyde in man and animals and the possible role for formaldehyde in reproductive and chronic respiratory disorders. It is the conclusion of the panel that formaldehyde should be presumed to pose a carcinogenic risk to humans. PMID:6977445

  6. Facile Synthesis of Quasi-One-Dimensional Au/PtAu Heterojunction Nanotubes and Their Application as Catalysts in an Oxygen-Reduction Reaction.

    PubMed

    Cai, Kai; Liu, Jiawei; Zhang, Huan; Huang, Zhao; Lu, Zhicheng; Foda, Mohamed F; Li, Tingting; Han, Heyou

    2015-05-11

    An intermediate-template-directed method has been developed for the synthesis of quasi-one-dimensional Au/PtAu heterojunction nanotubes by the heterogeneous nucleation and growth of Au on Te/Pt core-shell nanostructures in aqueous solution. The synthesized porous Au/PtAu bimetallic nanotubes (PABNTs) consist of porous tubular framework and attached Au nanoparticles (AuNPs). The reaction intermediates played an important role in the preparation, which fabricated the framework and provided a localized reducing agent for the reduction of the Au and Pt precursors. The Pt7 Au PABNTs showed higher electrocatalytic activity and durability in the oxygen-reduction reaction (ORR) in 0.1 M HClO4 than porous Pt nanotubes (PtNTs) and commercially available Pt/C. The mass activity of PABNTs was 218 % that of commercial Pt/C after an accelerated durability test. This study demonstrates the potential of PABNTs as highly efficient electrocatalysts. In addition, this method provides a facile strategy for the synthesis of desirable hetero-nanostructures with controlled size and shape by utilizing an intermediate template. PMID:25833689

  7. Fabrication of Te and Te-Au Nanowires-Based Carbon Fiber Fabrics for Antibacterial Applications

    PubMed Central

    Chou, Ting-Mao; Ke, Yi-Yun; Tsao, Yu-Hsiang; Li, Ying-Chun; Lin, Zong-Hong

    2016-01-01

    Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires (Te NWs) onto commercial carbon fiber fabrics and demonstrated their antibacterial activity. Those Te NWs can serve as templates and reducing agents for gold nanoparticles (Au NPs) to deposit. Three different Te-Au NWs with varied concentration of Au NPs were synthesized and showed superior antibacterial activity and biocompability. These results indicate that the as-prepared carbon fiber fabrics with Te and Te-Au NWs can become antimicrobial clothing products in the near future. PMID:26861380

  8. A Room-Temperature Operation Formaldehyde Sensing Material Printed Using Blends of Reduced Graphene Oxide and Poly(methyl methacrylate)

    PubMed Central

    Chuang, Wen-Yu; Yang, Sung-Yuan; Wu, Wen-Jong; Lin, Chih-Ting

    2015-01-01

    This work demonstrates a printable blending material, i.e., reduced graphene oxide (RGO) mixed with poly(methyl methacrylate) (PMMA), for formaldehyde sensing. Based on experimental results, 2% RGO/10% PMMA is an optimal ratio for formaldehyde detection, which produced a 30.5% resistance variation in response to 1000 ppm formaldehyde and high selectivity compared to different volatile organic compounds (VOCs), humidity, CO, and NO. The demonstrated detection limit is 100 ppm with 1.51% resistance variation. Characterization of the developed formaldehyde sensing material was performed by Fourier-transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), and Raman spectroscopy. Based on Raman spectroscopy, the basic sensing mechanism is the band distortion of RGO due to blending with PMMA and the adsorption of formaldehyde. This work establishes insights into the formaldehyde sensing mechanism and explores a potential printable sensing material for diverse applications. PMID:26580624

  9. Formaldehyde in hair straightening products: rapid ¹H NMR determination and risk assessment.

    PubMed

    Monakhova, Yulia B; Kuballa, Thomas; Mildau, Gerd; Kratz, Evamaria; Keck-Wilhelm, Andrea; Tschiersch, Christopher; Lachenmeier, Dirk W

    2013-04-01

    Despite official regulations, the illegal use of formaldehyde-containing or releasing hair straightening products has become a popular practice in Europe and high contents of formaldehyde in such products have been reported. In this study, a methodology utilizing (1)H NMR spectroscopy has been developed to measure the concentration of formaldehyde in hair straightening products. For sample preparation, a dilution and alkaline hydrolysis is required. The total formaldehyde content can then be quantified by a distinct peak of the CH2 group of the methanediol molecule in the δ4.84-4.82 ppm range. The developed methodology was applied for the analysis of 10 hair straightening products. Seven of these products contained detectable amounts of formaldehyde that were higher than the maximum allowed concentration of 0.2%. The formaldehyde content of these products was found to be in the range 0.42-5.83% with an average concentration of 1.46%. The accuracy and reliability of the NMR results were confirmed by the EU reference photometric method. The air formaldehyde concentrations after application of hair straightening products were estimated in ranges 20-423 ppm and 1-18 ppm (for 1 and 24 m(3) salon volume). A probabilistic exposure estimation using Monte Carlo simulation found the average formaldehyde concentration to be 6 ppm (standard deviation 15 ppm). All exposure scenarios considerably exceeded the safe level of 0.1 ppm. Our findings confirmed that the risk of cosmetic formulations with formaldehyde above 0.2% is not negligible, as these products may facilitate considerable exposure of formaldehyde for consumers especially for salon workers. PMID:23216202

  10. Au nanostructure arrays for plasmonic applications: annealed island films versus nanoimprint lithography.

    PubMed

    Lopatynskyi, Andrii M; Lytvyn, Vitalii K; Nazarenko, Volodymyr I; Guo, L Jay; Lucas, Brandon D; Chegel, Volodymyr I

    2015-01-01

    This paper attempts to compare the main features of random and highly ordered gold nanostructure arrays (NSA) prepared by thermally annealed island film and nanoimprint lithography (NIL) techniques, respectively. Each substrate possesses different morphology in terms of plasmonic enhancement. Both methods allow such important features as spectral tuning of plasmon resonance position depending on size and shape of nanostructures; however, the time and cost is quite different. The respective comparison was performed experimentally and theoretically for a number of samples with different geometrical parameters. Spectral characteristics of fabricated NSA exhibited an expressed plasmon peak in the range from 576 to 809 nm for thermally annealed samples and from 606 to 783 nm for samples prepared by NIL. Modelling of the optical response for nanostructures with typical shapes associated with these techniques (parallelepiped for NIL and semi-ellipsoid for annealed island films) was performed using finite-difference time-domain calculations. Mathematical simulations have indicated the dependence of electric field enhancement on the shape and size of the nanoparticles. As an important point, the distribution of electric field at so-called 'hot spots' was considered. Parallelepiped-shaped nanoparticles were shown to yield maximal enhancement values by an order of magnitude greater than their semi-ellipsoid-shaped counterparts; however, both nanoparticle shapes have demonstrated comparable effective electrical field enhancement values. Optimized Au nanostructures with equivalent diameters ranging from 85 to 143 nm and height equal to 35 nm were obtained for both techniques, resulting in the largest electrical field enhancement. The application of island film thermal annealing method for nanochips fabrication can be considered as a possible cost-effective platform for various surface-enhanced spectroscopies; while the NIL-fabricated NSA looks like more effective for

  11. Au nanostructure arrays for plasmonic applications: annealed island films versus nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Lopatynskyi, Andrii M.; Lytvyn, Vitalii K.; Nazarenko, Volodymyr I.; Guo, L. Jay; Lucas, Brandon D.; Chegel, Volodymyr I.

    2015-03-01

    This paper attempts to compare the main features of random and highly ordered gold nanostructure arrays (NSA) prepared by thermally annealed island film and nanoimprint lithography (NIL) techniques, respectively. Each substrate possesses different morphology in terms of plasmonic enhancement. Both methods allow such important features as spectral tuning of plasmon resonance position depending on size and shape of nanostructures; however, the time and cost is quite different. The respective comparison was performed experimentally and theoretically for a number of samples with different geometrical parameters. Spectral characteristics of fabricated NSA exhibited an expressed plasmon peak in the range from 576 to 809 nm for thermally annealed samples and from 606 to 783 nm for samples prepared by NIL. Modelling of the optical response for nanostructures with typical shapes associated with these techniques (parallelepiped for NIL and semi-ellipsoid for annealed island films) was performed using finite-difference time-domain calculations. Mathematical simulations have indicated the dependence of electric field enhancement on the shape and size of the nanoparticles. As an important point, the distribution of electric field at so-called `hot spots' was considered. Parallelepiped-shaped nanoparticles were shown to yield maximal enhancement values by an order of magnitude greater than their semi-ellipsoid-shaped counterparts; however, both nanoparticle shapes have demonstrated comparable effective electrical field enhancement values. Optimized Au nanostructures with equivalent diameters ranging from 85 to 143 nm and height equal to 35 nm were obtained for both techniques, resulting in the largest electrical field enhancement. The application of island film thermal annealing method for nanochips fabrication can be considered as a possible cost-effective platform for various surface-enhanced spectroscopies; while the NIL-fabricated NSA looks like more effective for sensing of

  12. Stabilization of AuNPs by monofunctional triazole linked to ferrocene, ferricenium, or coumarin and applications to synthesis, sensing, and catalysis.

    PubMed

    Li, Na; Zhao, Pengxiang; Igartua, María E; Rapakousiou, Amalia; Salmon, Lionel; Moya, Sergio; Ruiz, Jaime; Astruc, Didier

    2014-11-01

    Monofunctional triazoles linked to ferrocene, ferricenium, or coumarin (Cou), easily synthesized by copper-catalyzed azide alkyne (CuAAC) "click" reactions between the corresponding functional azides and (trimethylsilyl)acetylene followed by silyl group deprotection, provide a variety of convenient neutral ligands for the stabilization of functional gold nanoparticles (AuNPs) in polar organic solvents. These triazole (trz)-AuNPs are very useful toward a variety of applications to synthesis, sensing, and catalysis. Both ferrocenyl (Fc) and isostructural ferricenium linked triazoles give rise to AuNP stabilization, although by different synthetic routes. Indeed, the first direct synthesis and stabilization of AuNPs by ferricenium are obtained by the reduction of HAuCl4 upon reaction with a ferrocene derivative, AuNP stabilization resulting from a synergy between electrostatic and coordination effects. The ferricenium/ferrocene trz-AuNP redox couple is fully reversible, as shown by cyclic voltammograms that were recorded with both redox forms. These trz-AuNPs are stable for weeks in various polar solvents, but at the same time, the advantage of trz-AuNPs is the easy substitution of neutral trz ligands by thiols and other ligands, giving rise to applications. Indeed, this ligand substitution of trz at the AuNP surface yields a stable Fc-terminated nanogold-cored dendrimer upon reaction with a Fc-terminated thiol dendron, substitution of Cou-linked trz with cysteine, homocysteine, and glutathione provides remarkably efficient biothiol sensing, and a ferricenium-linked trz-AuNP catalyst is effective for NaBH4 reduction of 4-nitrophenol to 4-aminophenol. In this catalytic example, the additional electrostatic AuNP stabilization modulates the reaction rate and induction time. PMID:25363304

  13. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection.

    PubMed

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-19

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures. PMID:26016531

  14. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection

    NASA Astrophysics Data System (ADS)

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-01

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures.

  15. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

    PubMed

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively. PMID:26580661

  16. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application

    PubMed Central

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 μW/ cm2 in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm2, respectively. PMID:26580661

  17. Cyclotron produced 198gAu, a potential radionuclide for diagnostic and therapeutic applications

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Kassim, Hasan Abu

    2016-02-01

    Production cross-sections of the natPt(d,x)198Au reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. Only a partial agreement is obtained with the existing literature data and the theoretical data extracted from the TENDL-2013 library. Physical thick target yield for the 198Au radionuclide was deduced using the measured cross-sections, and found a general agreement with the directly measured yield available in the literature. This study reveals that a low deuteron energy (<15 MeV) cyclotron and an enriched 198Pt (100%) target could be used to obtain 198Au in no carrier added form.

  18. Production of radio-gold 199Au for diagnostic and therapeutic applications

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Kassim, Hasan Abu

    2016-01-01

    Production cross-sections of the natPt(d,x)199Au reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. Only a partial agreement is obtained with the existing literature data. Theoretical data extracted from the TENDL-2013 library shows large discrepancy with the measured ones. Physical thick target yield for the 199Au radionuclide was deduced using the measured cross-sections, and found a general agreement with the directly measured yield available in the literature. This study reveals that a low deuteron energy (<15 MeV) cyclotron and an enriched 198Pt (100%) target could be used to obtain 199Au in no carrier added form.

  19. Nonlinear stability of solar type 3 radio bursts. 2: Application to observations near 1 AU

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Smith, R. A.; Papadopoulos, K.

    1978-01-01

    A set of rate equations including strong turbulence effects and anomalous resitivity are solved using parmeters which model several solar type 3 bursts. Exciter distributions observed at 1 AU are excitation of the linear bump-in-tail instability, amplifying Langmuir waves above the threshold for the oscillating two stream instability (OTSI). The OTSI, and the attendant anomalous resistivity produce a rapid spectral transfer of Langmuir waves to short wavelengths, out of resonance with the electron exciter. Further energy loss of the beam is thus precluded. The various parameters needed to model the bursts are extrapolated inside 1 AU with similar results. Again, the OTSI is excited and decouples the electron beam from the Langmuir radiation. Reabsorption of the Langmuir waves by the beam is shown to be unimportant in all cases, even at 0.1 AU. The theory provides a natural explanation for the observed realationship between radio flux, and the electron flux.

  20. Controlled preparation of Au/Ag/SnO2 core-shell nanoparticles using a photochemical method and applications in LSPR based sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Na; Ye, Chen; Polavarapu, Lakshminarayana; Xu, Qing-Hua

    2015-05-01

    A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows the controlled preparation of various Au/Ag/SnO2 nanoparticles to adjust their LSPR to suit various applications.A photochemical method for the controlled preparation of core-shell Au/Ag/SnO2 nanorods (NRs) and nanospheres (NSs) has been developed based on photo-induced electron transfer processes in the plasmonic metal-semiconductor system. Au/AgNR/SnO2 and Au/AgNS/SnO2 were prepared by the UV irradiation of a mixture of mesoporous SnO2 coated AuNRs, or AuNSs, and AgNO3, in which AgNO3 was reduced by electrons transferred from the photo-excited mesoporous SnO2 (semiconductor) to the gold (metal). This method allows precise control over the composition and optical properties of the obtained nanoparticles. The LSPR refractive index sensitivity of the obtained Au/AgNR/SnO2 nanoparticles has been optimized to obtain a refractive index sensitivity of ~442 nm RIU-1. The optimized nanoparticles were subsequently chosen for the LSPR based sensing of glutathione (GSH) with the limit of detection of ~7.5 × 10-7 M. This photochemical method allows

  1. Collisional excitation of interstellar formaldehyde

    NASA Technical Reports Server (NTRS)

    Green, S.; Garrison, B. J.; Lester, W. A., Jr.; Miller, W. H.

    1978-01-01

    Previous calculations for rates of excitation of ortho-H2CO by collisions with He have been extended to higher rotational levels and kinetic temperatures to 80 K. Rates for para-H2CO have also been computed. Pressure-broadening widths for several spectral lines have been obtained from these calculations and are found to agree with recent data within the experimental uncertainty of 10%. Excitation of formaldehyde by collisions with H2 molecules is also discussed.

  2. Au-coated ZnO nanostructures for surface enhanced Raman spectroscopy applications

    SciTech Connect

    Dikovska, A O; Nedyalkov, N N; Imamova, S E; Atanasova, G B; Atanasov, P A

    2012-03-31

    Thin ZnO nanostructured films were produced by pulsed laser deposition (PLD) for surface enhanced Raman spectroscopy (SERS) studies. The experimental conditions used for preparation of the samples were chosen to obtain different types of ZnO nanostructures. The Raman spectra of rhodamine 6G (R6G) were measured at an excitation wavelength of 785 nm after coating the ZnO nanostructures with a thin Au layer. The influence of the surface morphology on the Raman signal obtained from the samples was investigated. High SERS signal enhancement was observed from all Au-coated ZnO nanostructures.

  3. Microencapsulated fragrances in melamine formaldehyde resins.

    PubMed

    Bône, Stéphane; Vautrin, Claire; Barbesant, Virginie; Truchon, Stéphane; Harrison, Ian; Geffroy, Cédric

    2011-01-01

    The process for making melamine formaldehyde microcapsules containing fragrant oil is well-known. Recently, this technology has been used to enhance the olfactory performance on fabrics. However keeping the fragrance in the capsule during storage, improving the olfactory benefit and releasing a low amount of formaldehyde is highly challenging. To answer these challenges, Givaudan has developed its own melamine formaldehyde microcapsule, called Mechacaps, which is described in this article. PMID:21528653

  4. Formaldehyde-releasers in cosmetics: relationship to formaldehyde contact allergy. Part 2. Patch test relationship to formaldehyde contact allergy, experimental provocation tests, amount of formaldehyde released, and assessment of risk to consumers allergic to formaldehyde.

    PubMed

    de Groot, Anton; White, Ian R; Flyvholm, Mari-Ann; Lensen, Gerda; Coenraads, Pieter-Jan

    2010-01-01

    This is the second part of an article on formaldehyde-releasers in cosmetics. The patch test relationship between the releasers in cosmetics to formaldehyde contact allergy is reviewed and it is assessed whether products preserved with formaldehyde-releasers may contain enough free formaldehyde to pose a threat to individuals with contact allergy to formaldehyde. There is a clear relationship between positive patch test reactions to formaldehyde-releasers and formaldehyde contact allergy: 15% of all reactions to 2-bromo-2-nitropropane-1,3-diol and 40-60% of the reactions to the other releasers are caused by a reaction to the formaldehyde in the test material. There is only fragmented data on the amount of free formaldehyde in cosmetics preserved with formaldehyde donors. However, all releasers (with the exception of 2-bromo-2-nitropropane-1,3-diol, for which adequate data are lacking) can, in the right circumstances of concentration and product composition, release >200 p.p.m. formaldehyde, which may result in allergic contact dermatitis. Whether this is actually the case in any particular product cannot be determined from the ingredient labelling. Therefore, we recommend advising patients allergic to formaldehyde to avoid leave-on cosmetics preserved with quaternium-15, diazolidinyl urea, DMDM hydantoin, or imidazolidinyl urea, acknowledging that many would tolerate some products. PMID:20136876

  5. In vitro model for decontamination of human skin: formaldehyde.

    PubMed

    Zhai, H; Barbadillo, S; Hui, X; Maibach, H I

    2007-04-01

    Decontamination of a chemical from skin is often an emergency measure. This study utilized an in vitro model to compare the decontamination capacity of three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline). Human cadaver skin was dosed (approximately 0.25 microg on 3 cm(2) per skin) with radio-labeled [(14)C]-formaldehyde. After a defined exposure time (1, 3, and 30 min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped with tape discs twice. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amounts of formaldehyde. Additionally, an evaporation test at different exposure times (1min, 3min, 15min, 30min, and 60min, respectively) was conducted to monitor formaldehyde % evaporation. There were no statistical differences among these groups except isotonic saline, at 3min post-exposure (in wash solutions), showed a significantly difference (p<0.05) when compared to tap water. Formaldehyde % evaporation increased linearly with extending application times, and were 7.7%, 13.6%, 19.7%, 24.4%, and 35.9% (1min, 3min, 15min, 30min, and 60min, respectively). This data suggests that isotonic saline may be effective in removing formaldehyde from skin. However, results from this model need validation in vivo. The model may provide a facile and robust method of accelerating knowledge of decontamination mechanism and lead to enhanced efficacy. PMID:17123683

  6. Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface-Enhanced Raman Scattering.

    PubMed

    Gao, Xiaonan; Esteves, Richard J Alan; Nahar, Lamia; Nowaczyk, Jordan; Arachchige, Indika U

    2016-05-25

    The direct cross-linking of Au/Ag alloy nanoparticles (NPs) into high surface area, mesoporous Au/Ag aerogels via chemical oxidation of the surface ligands is reported. The precursor alloy NPs with composition-tunable morphologies were produced by galvanic replacement of the preformed Ag hollow NPs. The effect of Au:Ag molar ratio on the NP morphology and surface plasmon resonance has been thoroughly investigated and resulted in smaller Au/Ag alloy NPs (4-8 nm), larger Au/Ag alloy hollow NPs (40-45 nm), and Au/Ag alloy hollow particles decorated with smaller Au NPs (2-5 nm). The oxidative removal of surfactant ligands, followed by supercritical drying, is utilized to construct large (centimeter to millimeter) self-supported Au/Ag alloy aerogels. The resultant assemblies exhibit high surface areas (67-73 m(2)/g), extremely low densities (0.051-0.055 g/cm(3)), and interconnected mesoporous (2-50 nm) networks, making them of great interest for a number of new technologies. The influence of mesoporous gel morphology on surface-enhanced Raman scattering (SERS) has been studied using Rhodamine 101 (Rd 101) as the probe molecule. The alloy aerogels exhibit SERS signal intensities that are 10-42 times higher than those achieved from the precursor Au/Ag alloy NPs. The Au/Ag alloy aerogel III exhibits SERS sensing capability down to 1 nM level. The increased signal intensities attained for alloy aerogels are attributed to highly porous gel morphology and enhanced surface roughness that can potentially generate a large number of plasmonic hot spots, creating efficient SERS substrates for future applications. PMID:27142886

  7. Approximate treatment of semicore states in GW calculations with application to Au clusters

    SciTech Connect

    Xian, Jiawei; Baroni, Stefano; Umari, P.

    2014-03-28

    We address the treatment of transition metal atoms in GW electronic-structure calculations within the plane-wave pseudo-potential formalism. The contributions of s and p semi-core electrons to the self-energy, which are essential to grant an acceptable accuracy, are dealt with using a recently proposed scheme whereby the exchange components are treated exactly at the G{sub 0}W{sub 0} level, whereas a suitable approximation to the correlation components is devised. This scheme is benchmarked for small gold nano-clusters, resulting in ionization potentials, electron affinities, and density of states in very good agreement with those obtained from calculations where s and p semicore states are treated as valence orbitals, and allowing us to apply this same scheme to clusters of intermediate size, Au{sub 20} and Au{sub 32}, that would be otherwise very difficult to deal with.

  8. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging.

    PubMed

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-28

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (∼15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (∼1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (∼76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection. PMID:26701141

  9. ZnO/Au-based surface plasmon resonance for CO2 gas sensing application

    NASA Astrophysics Data System (ADS)

    Nuryadi, Ratno; Mayasari, Rina Dewi

    2016-01-01

    We fabricate surface plasmon resonance (SPR) device using a modified ZnO/Au-Kretschmann configuration to investigate the possibility of using ZnO for CO2 gas sensing at room temperature. Here, nanostructured ZnO/Au layer was deposited on the flat surface of the prism and then gas chamber was placed on the ZnO/Au surface to observe the gas response. The ZnO structures were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. We found that ZnO structures have two types of nanostructures, i.e., individual nanorods and flower-like structures, which have hexagonal crystal structure. The ZnO nanorod has a diameter ranged from 200 to 300 nm and length ranged from 3 to 5 μm. The effect of gas response is demonstrated by a shift of SPR spectra and a change in light reflectance. It is found that the adsorption of gas molecules on the ZnO nanorods produces the shift of SPR angle to the lower light incident angle. A consistent sensing behavior over repetitive circles is also demonstrated.

  10. Formaldehyde concentrations in biology department teaching facilities

    SciTech Connect

    Korky, J.K.; Schwarz, S.R.; Lustigman, B.K.

    1987-05-01

    As students and faculty in the biological sciences can attest, low grade exposure to formaldehyde by skin contact and inhalation during dissection is quite irritating. Health effects noted upon exposure to formaldehyde at concentrations of 0.1 to 5 ppm are burning of the eyes, lacrimation, and general irritation to the upper respiratory passages. Symptoms reported for higher exposures, 10 to 20 ppm, include coughing, tightening of the chest, headache and palpitation of the heart. Long exposures at 50 to 100 ppm or more might result in pulmonary edema, pneumonitis, and even death. There is also concern with regard to potential long term detrimental effects. Formaldehyde has been cited as a possible carcinogen in animals. It is a known mutagen in laboratory experimental systems involving Drosophilia, grasshoppers, flowering plants, fungi and bacteria. Animal testing has led investigators to postulate that the primary damage resulting from formaldehyde exposure may involve DNA synthesis and ribosomal RNA transcription. The National Institute of Occupational Safety and Health Administration (NIOSH) investigators have been studying occupational exposure to formaldehyde for over a decade in a variety of industries. This study was undertaken to assess formaldehyde concentrations in biology department dissecting facilities in the 1982-1983 academic year in order if routine dissection produces levels of formaldehyde which were unsafe according to NIOSH and OSHA standards. Chronic formaldehyde exposure is cause for greater concern than incidental exposure.

  11. Formaldehyde monitoring program: development of sampling and analysis procedures

    SciTech Connect

    Matthews, T. G.; Hawthorne, A. R.

    1980-01-01

    This report outlines the scope and goals of the formaldehyde analysis program being carried out in Health and Safety Research Division of the Oak Ridge National Laboratory under contract of the US Consumer Product Safety Commission. The outline of the sampling and analysis techniques under consideration, with reference to a time frame for developmental work and field application, is discussed. The complexity of the different techniques is addressed in instances where technical staff would be requird for accurate operation of the instrumentation.

  12. Effect of an ozone-generating air-purifying device on reducing concentrations of formaldehyde in air

    SciTech Connect

    Esswein, E.J.; Boeniger, M.F.

    1994-02-01

    Formaldehyde, an air contaminant found in many indoor air investigations, poses distinct occupational exposure hazards in certain job categories (e.g., mortuary science) but is also of concern when found or suspected in office buildings and homes. A variety of air-purifying devices (APDs) are currently available or marketed for application to reduce or remove concentrations of a variety of indoor air pollutants through the use of ozone as a chemical oxidant. An investigation was conducted to determine if concentrations of formaldehyde similar to those found in industrial hygiene evaluations of funeral homes could be reduced with the use of an ozone-generating APD. An ozone-generating APD was placed in an exposure chamber and formaldehyde-containing embalming solution was allowed to evaporate naturally, creating peak and mean chamber concentrations of 2.5 and 1.3 ppm, respectively. Continuous-reading instruments were used to sample for formaldehyde and ozone. Active sampling methods were also used to sample simultaneously for formaldehyde and a possible reactant product, formic acid. Triplicate measurements were made in each of three evaluations: formaldehyde alone, ozone alone, and formaldehyde and ozone combined. Concentrations of formaldehyde were virtually identical with and without 0.5 ppm ozone. No reduction in formaldehyde concentration was found during a 90-minute evaluation using ozone at this concentration with peak and average concentrations of approximately 2.5 and 1.3 ppm formaldehyde, respectively. The results of this investigation suggest that the use of ozone is ineffective in reducing concentrations of formaldehyde. Because ozone has demonstrated health hazards, and is a regulated air contaminant in both the occupational and ambient environment, the use of ozone as an air purification agent in indoor air does not seem warranted. 25 refs., 5 figs., 4 tabs.

  13. Electrooxidation of formaldehyde based on nickel-palladium modified ordered mesoporous silicon.

    PubMed

    Miao, Fengjuan; Tao, Bairui

    2013-04-01

    Nickel and palladium nanoparticles were finely dispersed on ordered mesoporous silicon microchannels plate (MCP) by electroless plating. The structure and composition of the resulting Ni-Pd/Si MCP were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The electrocatalystic properties of Ni-Pd/Si MCP electrode for formaldehyde oxidation have been investigated by cyclic voltammetry. The results show that Ni-Pd/Si MCP has a higher catalytic activity and better steady-state behavior for formaldehyde oxidation. This may be attributed to the synergistic property of high dispersion of Nickel and Palladium nanoparticles and particular properties of mesoporous Si MCP. The present study shows a promising choice of Ni-Pd nanoparticles supported by mesoporous silicon as effective electrocatalyst for formaldehyde electrooxidation in alkaline medium. The results imply that the Ni-Pd/Si MCP nanocomposite has good potential application in formaldehyde fuel cells and sensors. PMID:23763207

  14. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium.

    PubMed

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-01-01

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O8(2-) system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01-100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore. PMID:26902375

  15. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium

    PubMed Central

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-01-01

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O82− system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01–100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore. PMID:26902375

  16. Formaldehyde Absorption toward W51

    SciTech Connect

    Kogut, A.; Smoot, G.F.; Bennett, C.L.; Petuchowski, S.J.

    1988-04-01

    We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be quite patchy. We list the properties of the opacity spectra for a number of positions both in the clumps and in the more diffuse regions of the absorbing clouds, and derive column densities for the 1{sub 11} and 2{sub 12} rotational levels of ortho-formaldehyde.

  17. Study of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au8 quantum clusters for Hg2+ ion sensing, cellular imaging and antibacterial applications

    NASA Astrophysics Data System (ADS)

    Khandelwal, Puneet; Singh, Dheeraj K.; Sadhu, Subha; Poddar, Pankaj

    2015-11-01

    Herein, we report a detailed experimental study supported by DFT calculations to understand the mechanism behind the synthesis of cefradine (CFD - an antibiotic) labeled gold nanoparticles (Au NPs) by employing CFD as both a mild reducing and capping agent. The analysis of the effect of growth conditions reveals that a higher concentration of HAuCl4 results in the formation of an increasing fraction of anisotropic structures, higher temperature leads to the formation of quasi-spherical particles instead of anisotropic ones, and larger pH leads to the formation of much smaller particles. The cyclic voltammetry (CV) results show that when the pH of the reaction medium increases from 4 to 6, the reduction potential of CFD increases which leads to the synthesis of nanoparticles (in a pH 4 reaction) to quantum clusters (in a pH 6 reaction). The MALDI-TOF mass spectrometry results of supernatant of the pH 6 reaction indicate the formation of [Au8(CFD)2S6] QCs which show fluorescence at ca. 432 nm with a Stokes shift of ca. 95 nm. The blue luminescence from Au8 QCs was applied for sensing of Hg2+ ions on the basis of an aggregation-induced fluorescence quenching mechanism and offers good selectivity and a high sensitivity with a limit of detection ca. 2 nM which is lower than the detection requirement of 10 nM by the U.S. EPA and 30 nM by WHO for drinking water. We have also applied the sensing probe to detect Hg2+ ions in bacterial samples. Further, we have investigated the antibacterial property of as-synthesized Au NPs using MIC, growth curve and cell survival assay. The results show that Au NPs could reduce the cell survival very efficiently rather than the cell growth in comparison to the antibiotic itself. The scanning electron microscopy study shows the degradation and blebbing of the bacterial cell wall upon exposure with Au NPs which was further supported by fluorescence microscopy results. These Au NPs did not show reactive oxygen species generation. We believe

  18. Optical properties of random alloys: application to CuAu and NiPt

    NASA Astrophysics Data System (ADS)

    Krishna Saha, Kamal; Mookerjee, Abhijit

    2005-07-01

    In an earlier paper we presented a formulation for the calculation of the configuration-averaged optical conductivity in random alloys. Our formulation is based on the augmented-space theorem introduced by one of us (Mookerjee 1973 J. Phys. C: Solid State Phys. 6 1340). In this communication we shall combine the augmented space methodology with the tight-binding linear muffin-tin orbital technique (TB-LMTO) to study the optical conductivities of two alloys, CuAu and NiPt.

  19. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging

    NASA Astrophysics Data System (ADS)

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-01

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection.Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on

  20. Asymmetric Aldol Reaction with Formaldehyde: a Challenging Process.

    PubMed

    Meninno, Sara; Lattanzi, Alessandra

    2016-08-01

    The asymmetric aldol reaction with formaldehyde is a fundamental carbon-carbon bond-forming reaction in organic synthesis, as well as in the quest of the origin of life, as it is thought to have been the first "molecular brick" involved in the synthetic path to complex sugars. Products of aldol reactions, i.e., the β-hydroxy carbonyl compounds, are versatile building blocks used to access a great variety of functionalised molecules. The employment of formaldehyde, as a C1 symmetric electrophile, in aldol reactions can be likely considered the most challenging, yet simplest, process to introduce a hydroxymethyl group in an asymmetric fashion. In this account, an overview of the progress achieved in the asymmetric metal- and organocatalysed aldol reaction, using readily available formalin or paraformaldehyde sources, is illustrated. Our recent contribution to this area, with the application of asymmetric hydroxymethylation in cascade processes for the synthesis of γ-butyrolactones, is also shown. PMID:27328802

  1. Formaldehyde Exposures in a University Anatomy Laboratory

    NASA Astrophysics Data System (ADS)

    Winkler, Kyle William

    Air sampling studies were conducted within a university anatomical laboratory during the embalmment of a cadaver in order to determine if dangerous concentrations of formaldehyde existed. Three air sampling studies were conducted in the anatomical laboratory on three separate days that a cadaver was being embalmed. Samples were collected and analyzed using the Occupational Safety and Health Administration (OSHA) Sampling and Analytical Methods: Method 52. Each air sampling study sampled for short term exposure limit (STEL) and time weighted mean (TWA) breathing zone formaldehyde concentrations as well as area TWA formaldehyde concentrations. A personal aldehyde monitor was also used in each air sampling study to sample for breathing zone formaldehyde concentrations. Measured TWA mean exposures to formaldehyde ranged from 0.15--1.3 parts per million (ppm), STEL formaldehyde exposures ranged from 0.019--0.64 ppm, and eight-hour TWAs ranged from 0.03 to 3.6 ppm. All 8-hour TWA formaldehyde concentrations sampled in the anatomy laboratory during an embalmment were less than the permissible exposure limit (PEL) required by OSHA.

  2. Mechanistic study on formaldehyde-induced hepatotoxicity

    SciTech Connect

    Strubelt, O.; Younes, M.; Pentz, R.; Kuehnel, W. )

    1989-01-01

    In isolated, hemoglobin-free perfused livers of fasted rats, formaldehyde at an initial concentration of 10 mmol/l produced toxicity as evidenced by a release of enzymes (GPT, SDH) and of glutathione (mainly GSSG) into the perfusate, an accumulation of calcium in the liver, and a depletion of hepatic glatathione. Formaldehyde also led to an enhanced release of malondialdehyde into the perfusate, indicating peroxidative processes and decreased hepatic oxygen consumption by about 50-70%. The electron microscopic investigation of formaldehyde-exposed livers showed a destruction of the mitochondria (ruptured membranes, loss of the cristae) and some damage of the rough endoplasmic reticulum. Feeding the rats prior to surgery attenuated the hepatotoxic effects of 10 mmol/l formaldehyde. At an initial concentration of 3 mmol/l, formaldehyde did not release enzymes from livers of fed or fasted rats but only from whose glutathione content had been depleted by treatment with phorone (250 mg/kg ip 2 h earlier). Formaldehyde liberated glucose and lactate from the livers of fed but not from those of fasted rats, indicating anaerobic energy supply in the fed state. The hepatotoxic action of formaldehyde is not due to its metabolism to formate or to the 10% methanol added as a stabilizing agent to the commercially available 37% solution named formalin.

  3. Formaldehyde asthma--rare or overlooked

    SciTech Connect

    Nordman, H.; Keskinen, H.; Tuppurainen, M.

    1985-01-01

    A total of 230 persons who had been exposed to formaldehyde and suffered from asthma-like respiratory symptoms were examined between January 1, 1977, and May 31, 1983. All the subjects had a bronchial provocation test with formaldehyde. On the basis of the medical and occupational history of the patients, the specific bronchial provocation test, and other test results, 12 cases were considered to be caused by specific sensitization to formaldehyde. All subjects had been exposed occupationally. An exposure period of between 1 mo and 19 yr preceded the onset of symptoms. Three persons displayed no bronchial hyperreactivity as assessed with a histamine or metacholine provocation test. Eleven of the 12 reactions were triggered by about 2.5 mg/m3 and one reaction by about 1.2 mg/m3 of formaldehyde. The late reaction in 1 patient was completely blocked by the inhalation of 100 micrograms of beclomethasone di-isoproprionate before the challenge with formaldehyde. Seventy-one of the 218 subjects who did not react when they were challenged with formaldehyde demonstrated bronchial hyperreactivity. The authors conclude that formaldehyde asthma, although apparently a rare disease, is under reported. Removal from exposure has a favorable effect on the symptoms. Low domestic exposures, however, may maintain the symptoms in individuals already sensitized.

  4. Cu2O and Au/Cu2O particles: surface properties and applications in glucose sensing.

    PubMed

    Won, Yu-Ho; Stanciu, Lia A

    2012-01-01

    In this work we investigated the surface and facet-dependent catalytic properties of metal oxide particles as well as noble metal/metal oxide heterogeneous structures, with cuprous oxide (Cu(2)O) and Au/Cu(2)O being selected as model systems. As an example of application, we explored the potential of these materials in developing electrocatalytic devices. Cu(2)O particles were synthesized in various shapes, then used for testing their morphology-dependent electrochemical properties applied to the detection of glucose. While we did not attempt to obtain the best detection limit reported to date, the octahedral and hexapod Cu(2)O particles showed reasonable detection limits of 0.51 and 0.60 mM, respectively, which are physiologically relevant concentrations. However, detection limit seems to be less affected by particle shapes than sensitivity. Heterogeneous systems where Au NPs were deposited on the surface of Cu(2)O particles were also tested with similar results in terms of the effect of surface orientation. PMID:23201983

  5. Cu2O and Au/Cu2O Particles: Surface Properties and Applications in Glucose Sensing

    PubMed Central

    Won, Yu-Ho; Stanciu, Lia A.

    2012-01-01

    In this work we investigated the surface and facet-dependent catalytic properties of metal oxide particles as well as noble metal/metal oxide heterogeneous structures, with cuprous oxide (Cu2O) and Au/Cu2O being selected as model systems. As an example of application, we explored the potential of these materials in developing electrocatalytic devices. Cu2O particles were synthesized in various shapes, then used for testing their morphology-dependent electrochemical properties applied to the detection of glucose. While we did not attempt to obtain the best detection limit reported to date, the octahedral and hexapod Cu2O particles showed reasonable detection limits of 0.51 and 0.60 mM, respectively, which are physiologically relevant concentrations. However, detection limit seems to be less affected by particle shapes than sensitivity. Heterogeneous systems where Au NPs were deposited on the surface of Cu2O particles were also tested with similar results in terms of the effect of surface orientation. PMID:23201983

  6. Hybridized doxorubicin-Au nanospheres exhibit enhanced near-infrared surface plasmon absorption for photothermal therapy applications.

    PubMed

    Zhou, Jialin; Wang, Zuhua; Li, Qingpo; Liu, Fei; Du, Yongzhong; Yuan, Hong; Hu, Fuqiang; Wei, Yinghui; You, Jian

    2015-03-19

    Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold nanospheres by synthesizing hybridized DOX-Au nanospheres (DAuNS), where a part of the DOX molecules and Au co-formed a hybridized matrix as the shell and the remaining DOX molecules precipitated as the core. The unique structure of DAuNS induced interesting changes in the characteristics including spectrum properties, morphology, drug loading and antitumor activity. We observed that DAuNS exhibited a significantly enhanced surface plasmon absorption in the NIR region, inducing a more efficient photothermal conversion and stronger tumor-cell killing ability under NIR laser irradiation. In addition, our study presents a new and simple platform to load a drug into nanoparticles. DAuNS could be a promising nanoparticle with the "two punch" efficacy of PTT and chemotherapy and could be used in clinical applications due to its controllable synthesis, small size, and narrow size distribution. PMID:25757809

  7. Formaldehyde preparation methods for pressure and temperature dependent laser-induced fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Müller, D.; Rieger, S.; Schmidl, G.; Triebel, W.; Paa, W.

    2015-12-01

    Formaldehyde is an excellent tracer for the early phase of ignition of hydrocarbon fuels and can be used, e.g., for characterization of single droplet ignition. However, due to its fast thermal decomposition at elevated temperatures and pressures, the determination of concentration fields from laser-induced fluorescence (LIF) measurements is difficult. In this paper, we address LIF measurements of this important combustion intermediate using a calibration cell. Here, formaldehyde is created from evaporation of paraformaldehyde. We discuss three setups for preparation of formaldehyde/air mixtures with respect to their usability for well-defined heating of formaldehyde/air mixtures. The "basic setup" uses a resist heater around the measurement cell for investigation of formaldehyde near vacuum conditions or formaldehyde/air samples after sequential admixing of air. The second setup, described for the first time in detail here, takes advantage of a constant flow formaldehyde/air regime which uses preheated air to reduce the necessary time for gas heating. We used the constant flow system to measure new pressure dependent LIF excitation spectra in the 343 nm spectral region (414 absorption band of formaldehyde). The third setup, based on a novel concept for fast gas heating via excitation of SF6 (chemically inert gas) using a TEA (transverse excitation at atmospheric pressure) CO2 laser, allows to further minimize both gas heating time and thermal decomposition. Here, an admixture of CO2 is served for real time temperature measurement based on Raman scattering. The applicability of the fast laser heating system has been demonstrated with gas mixtures of SF6 + air, SF6 + N2, as well as SF6 + N2 + CO2 at 1 bar total pressure.

  8. Formaldehyde preparation methods for pressure and temperature dependent laser-induced fluorescence measurements.

    PubMed

    Burkert, A; Müller, D; Rieger, S; Schmidl, G; Triebel, W; Paa, W

    2015-12-01

    Formaldehyde is an excellent tracer for the early phase of ignition of hydrocarbon fuels and can be used, e.g., for characterization of single droplet ignition. However, due to its fast thermal decomposition at elevated temperatures and pressures, the determination of concentration fields from laser-induced fluorescence (LIF) measurements is difficult. In this paper, we address LIF measurements of this important combustion intermediate using a calibration cell. Here, formaldehyde is created from evaporation of paraformaldehyde. We discuss three setups for preparation of formaldehyde/air mixtures with respect to their usability for well-defined heating of formaldehyde/air mixtures. The "basic setup" uses a resist heater around the measurement cell for investigation of formaldehyde near vacuum conditions or formaldehyde/air samples after sequential admixing of air. The second setup, described for the first time in detail here, takes advantage of a constant flow formaldehyde/air regime which uses preheated air to reduce the necessary time for gas heating. We used the constant flow system to measure new pressure dependent LIF excitation spectra in the 343 nm spectral region (41 (4) absorption band of formaldehyde). The third setup, based on a novel concept for fast gas heating via excitation of SF6 (chemically inert gas) using a TEA (transverse excitation at atmospheric pressure) CO2 laser, allows to further minimize both gas heating time and thermal decomposition. Here, an admixture of CO2 is served for real time temperature measurement based on Raman scattering. The applicability of the fast laser heating system has been demonstrated with gas mixtures of SF6 + air, SF6 + N2, as well as SF6 + N2 + CO2 at 1 bar total pressure. PMID:26724008

  9. Urea formaldehyde foam: a dangerous insulation

    SciTech Connect

    Keough, C.

    1980-12-01

    Insulating a home with urea formaldehyde foam can lead to severe health problems due to poisoning from formaldehyde gas. Respiratory problems, allergies, memory loss, and mental problems can result from exposure to foam insulation fumes. Research is now under way at the Chemical Industry Inst., Univ. of Washington, and other institutions to learn more about the health effects of formaldehyde foam and to develop possible remedies to these problems. Several states are either banning or controlling the use of this type of home insulation.

  10. Crystallographic investigation of Au nanoparticles embedded in a SrTiO{sub 3} thin film for plasmonics applications by means of synchrotron radiation

    SciTech Connect

    Pincini, Davide; Mazzoli, Claudio; Bernhardt, Hendrik; Katzer, Christian; Schmidl, Frank; Uschmann, Ingo; Detlefs, Carsten

    2015-03-14

    Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO{sub 3} matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with [110]{sub SrTiO{sub 3}}∥[110]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with [100]{sub SrTiO{sub 3}}∥[100]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.

  11. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    NASA Astrophysics Data System (ADS)

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-11-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at -0.65 V, -0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes.

  12. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    PubMed Central

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-01-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at −0.65 V, −0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes. PMID:26577799

  13. 78 FR 34795 - Formaldehyde; Third-Party Certification Framework for the Formaldehyde Standards for Composite...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ..., automotive, and food and consumer products. The standards used in third-party certification are typically... TPCs and their formaldehyde emissions testing laboratories. EPA would exercise authority to...

  14. Enhanced Formaldehyde Detoxification by Overexpression of Glutathione-Dependent Formaldehyde Dehydrogenase from Arabidopsis1

    PubMed Central

    Achkor, Hakima; Díaz, Maykelis; Fernández, M. Rosario; Biosca, Josep Antoni; Parés, Xavier; Martínez, M. Carmen

    2003-01-01

    The ADH2 gene codes for the Arabidopsis glutathione-dependent formaldehyde dehydrogenase (FALDH), an enzyme involved in formaldehyde metabolism in eukaryotes. In the present work, we have investigated the potential role of FALDH in detoxification of exogenous formaldehyde. We have generated a yeast (Saccharomyces cerevisiae) mutant strain (sfa1Δ) by in vivo deletion of the SFA1 gene that codes for the endogenous FALDH. Overexpression of Arabidopsis FALDH in this mutant confers high resistance to formaldehyde added exogenously, which demonstrates the functional conservation of the enzyme through evolution and supports its essential role in formaldehyde metabolism. To investigate the role of the enzyme in plants, we have generated Arabidopsis transgenic lines with modified levels of FALDH. Plants overexpressing the enzyme show a 25% increase in their efficiency to take up exogenous formaldehyde, whereas plants with reduced levels of FALDH (due to either a cosuppression phenotype or to the expression of an antisense construct) show a marked slower rate and reduced ability for formaldehyde detoxification as compared with the wild-type Arabidopsis. These results show that the capacity to take up and detoxify high concentrations of formaldehyde is proportionally related to the FALDH activity in the plant, revealing the essential role of this enzyme in formaldehyde detoxification. PMID:12913179

  15. Resorcinol-formaldehyde and carbon aerogel microspheres

    SciTech Connect

    Alviso, C.T.; Pekela, R.W.; Gross, J.; Lu, X.; Caps, R.; Fricke, J

    1996-04-01

    Aerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100nm), high surface area (400--1100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10--80{mu} diameter) which can be used as loosely packed powders, compression molded into near-net shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.

  16. Design of highly sensitive and selective Au@NiO yolk-shell nanoreactors for gas sensor applications.

    PubMed

    Rai, Prabhakar; Yoon, Ji-Wook; Jeong, Hyun-Mook; Hwang, Su-Jin; Kwak, Chang-Hoon; Lee, Jong-Heun

    2014-07-21

    Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H₂S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH₃, CO and H₂). The maximum response was 108.92 for 5 ppm of H₂S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H₂S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H₂S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response. PMID:24933405

  17. Facile Synthesis of Au-Coated Magnetic Nanoparticles and Their Application in Bacteria Detection via a SERS Method.

    PubMed

    Wang, Junfeng; Wu, Xuezhong; Wang, Chongwen; Rong, Zhen; Ding, Hongmei; Li, Hui; Li, Shaohua; Shao, Ningsheng; Dong, Peitao; Xiao, Rui; Wang, Shengqi

    2016-08-10

    This study proposes a facile method for synthesis of Au-coated magnetic nanoparticles (AuMNPs) core/shell nanocomposites with nanoscale rough surfaces. MnFe2O4 nanoparticles (NPs) were first modified with a uniform polyethylenimine layer (2 nm) through self-assembly under sonication. The negatively charged Au seeds were then adsorbed on the surface of the MnFe2O4 NPs through electrostatic interaction for Au shell formation. Our newly developed sonochemically assisted hydroxylamine seeding growth method was used to grow the adsorbed gold seeds into large Au nanoparticles (AuNPs) to form a nanoscale rough Au shell. Au-coated magnetic nanoparticles (AuMNPs) were obtained from the intermediate product (Au seeds decorated magnetic core) under sonication within 5 min. The AuMNPs were highly uniform in size and shape and exhibited satisfactory surface-enhanced Raman scattering (SERS) activity and strong magnetic responsivity. PATP was used as a probe molecule to evaluate the SERS performance of the synthesized AuMNPs with a detection limit of 10(-9) M. The synthesized AuMNPs were conjugated with Staphylococcus aureus (S. aureus) antibody for bacteria capture and separation. The synthesized plasmonic AuNR-DTNB NPs, whose LSPR wavelength was adjusted to the given laser excitation wavelength (785 nm), were conjugated with S. aureus antibody to form a SERS tag for specific recognition and report of the target bacteria. S. aureus was indirectly detected through SERS based on sandwich-structured immunoassay, with a detection limit of 10 cells/mL. Moreover, the SERS intensity at Raman peak of 1331 cm(-1) exhibited a linear relationship to the logarithm of bacteria concentrations ranging from 10(1) cells/mL to 10(5) cells/mL. PMID:27420923

  18. A brief review of control measures for indoor formaldehyde

    SciTech Connect

    Matthews, T.G.

    1988-01-01

    Indoor environments contain a variety of consumer and construction products that emit formaldehyde (CH/sub 2/O) vapor. The strongest CH/sub 2/O emitters are typically particleboard underlayment and industrial particleboard, hardwood plywood paneling, urea-formaldehyde foam insulation, and medium density fiberboard, all of which contain urea-formaldehyde (UF) resins. The contribution of individual products to indoor CH/sub 2/O levels depends on several parameters, including the quantity and age of the product, building ventilation rate, presence of permeation barriers, temperature (T), relative humidity (RH), and CH/sub 2/O vapor concentration resulting from all of the CH/sub 2/O emitters (1,3-8). Combustion sources (e.g., kerosene heaters, gas stoves and cigarettes), carpet and carpet padding, resilient flooring (e.g., linoleum), gypsum board, non-apparel and apparel textiles, ceiling tiles, fibrous glass insulation and softwood plywood subflooring are generally weak emitters that do not contribute significantly to steady-state, indoor CH/sub 2/O levels. Control measures exist to reduce CH/sub 2/O emissions from consumer and construction products during their manufacturer and in post-installation applications. This note summarized the effectiveness of the following subset of post-installation control measures: product aging, installations of permeation barriers (i.e., flooring) and increased building ventilation. 14 refs.

  19. Health and Environmental Effects Profile for Formaldehyde

    EPA Science Inventory

    The Health and Environmental Effects Profile for formaldehyde was prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency Response to support listings of hazardous cons...

  20. HETEROGENOUS PHOTOREACTION OF FORMALDEHYDE WITH HYDROXYL RADICALS

    EPA Science Inventory

    Atmospheric heterogeneous photoreactions occur between formaldehyde and hydroxyl radicals to produce formic acid. hese photoreactions not only occur in clouds, but also in other tropospheric hydrometeors such as precipitation and dew droplets. xperiments were performed by irradia...

  1. Contribution of formaldehyde to respiratory cancer.

    PubMed Central

    Nelson, N; Levine, R J; Albert, R E; Blair, A E; Griesemer, R A; Landrigan, P J; Stayner, L T; Swenberg, J A

    1986-01-01

    This article reviews the available data on the carcinogenicity of formaldehyde from experimental and epidemiologic studies and makes recommendations for further research. Two definitive chronic inhalation bioassays on rodents have demonstrated that formaldehyde produces nasal cancer in rats and mice at 14 ppm and in rats at 6 ppm, which is within the domain of present permissible human exposure (8-hr time-weighted average of 3 ppm, a 5 ppm ceiling, and a 10 ppm short-term exposure limit). Biochemical and physiologic studies in rats have shown that inhaled formaldehyde can depress respiration, inhibit mucociliary clearance, stimulate cell proliferation, and crosslink DNA and protein in the nasal mucosa. No deaths from nasal cancer have been reported in epidemiologic studies of cohorts exposed to formaldehyde, but three case-control studies suggest the possibility of increased risk. Although excesses of lung cancer deaths have been observed in some studies at industrial plants with formaldehyde exposure, uncertainties in interpretation limit the evaluation of these findings. Excess cancers of the brain and of lymphatic and hematopoietic tissues have been reported in certain studies of industrial groups and in most studies of formaldehyde-exposed professionals, but whether these excesses are related to formaldehyde exposure is not known. Several properties of formaldehyde pose unique problems for future research: the mechanisms responsible for its nonlinear response; its probable mechanism of carcinogenic action as a cross-linking agent; its formation in tissues as a normal metabolite; its possible action as a promoter and/or a cocarcinogen; and the importance of glutathione as a host defense at low exposure. PMID:3830109

  2. Report on the Consensus Workshop on Formaldehyde.

    PubMed Central

    1984-01-01

    The Consensus Workshop on Formaldehyde consisted of bringing together scientists from academia, government, industry and public interest groups to address some important toxicological questions concerning the health effects of formaldehyde. The participants in the workshop, the Executive Panel which coordinated the meeting, and the questions posed, all were chosen through a broadly based nomination process in order to achieve as comprehensive a consensus as possible. The subcommittees considered the toxicological problems associated with formaldehyde in the areas of exposure, epidemiology, carcinogenicity/histology/genotoxicity, immunology/sensitization/irritation, structure activity/biochemistry/metabolism, reproduction/teratology, behavior/neurotoxicity/psychology and risk estimation. Some questions considered included the possible human carcinogenicity of formaldehyde, as well as other human health effects, and the interpretation of pathology induced by formaldehyde. These reports, plus introductory material on the procedures used in setting up the Consensus Workshop are presented here. Additionally, there is included a listing of the data base that was made available to the panel chairmen prior to the meeting and was readily accessible to the participants during their deliberations in the meeting. This data base, since it was computerized, was also capable of being searched for important terms. These materials were supplemented by information brought by the panelists. The workshop has defined the consensus concerning a number of major points in formaldehyde toxicology and has identified a number of major deficits in understanding which are important guides to future research. PMID:6525992

  3. Report on the Consensus Workshop on Formaldehyde.

    PubMed

    1984-12-01

    The Consensus Workshop on Formaldehyde consisted of bringing together scientists from academia, government, industry and public interest groups to address some important toxicological questions concerning the health effects of formaldehyde. The participants in the workshop, the Executive Panel which coordinated the meeting, and the questions posed, all were chosen through a broadly based nomination process in order to achieve as comprehensive a consensus as possible. The subcommittees considered the toxicological problems associated with formaldehyde in the areas of exposure, epidemiology, carcinogenicity/histology/genotoxicity, immunology/sensitization/irritation, structure activity/biochemistry/metabolism, reproduction/teratology, behavior/neurotoxicity/psychology and risk estimation. Some questions considered included the possible human carcinogenicity of formaldehyde, as well as other human health effects, and the interpretation of pathology induced by formaldehyde. These reports, plus introductory material on the procedures used in setting up the Consensus Workshop are presented here. Additionally, there is included a listing of the data base that was made available to the panel chairmen prior to the meeting and was readily accessible to the participants during their deliberations in the meeting. This data base, since it was computerized, was also capable of being searched for important terms. These materials were supplemented by information brought by the panelists. The workshop has defined the consensus concerning a number of major points in formaldehyde toxicology and has identified a number of major deficits in understanding which are important guides to future research. PMID:6525992

  4. Precisely controlled resorcinol-formaldehyde resin coating for fabricating core-shell, hollow, and yolk-shell carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Fang, Xiaoliang; Liu, Shengjie; Zang, Jun; Xu, Chaofa; Zheng, Ming-Sen; Dong, Quan-Feng; Sun, Daohua; Zheng, Nanfeng

    2013-07-01

    This work provides a facile one-step sol-gel route to synthesize high-quality resorcinol-formaldehyde (RF) resin coated nanocomposites that can be further used to fabricate desired carbon nanostructures. Colloidal particles with different morphologies and sizes can be coated with high-quality RF resin shells by the proposed cationic surfactant assisted RF resin coating strategy. The as-synthesized RF resin coated nanocomposites are ideal candidates for selective synthesis of core-shell, hollow, and yolk-shell carbon nanostructures. Based on the carboxylic functional RF resin coating, graphitic carbon nanostructures can also be synthesized by employing the graphitization catalyst. The as-synthesized carbon nanostructures show the advantageous performances in several applications. Hollow carbon spheres are potential electrode materials for lithium-sulfur batteries. Hollow graphitic spheres are promising catalyst supports for oxygen reduction reaction. And yolk-shell structured Au@HCS nanoreactors with ultrathin shells exhibit high catalytic activity and recyclability in confined catalysis.This work provides a facile one-step sol-gel route to synthesize high-quality resorcinol-formaldehyde (RF) resin coated nanocomposites that can be further used to fabricate desired carbon nanostructures. Colloidal particles with different morphologies and sizes can be coated with high-quality RF resin shells by the proposed cationic surfactant assisted RF resin coating strategy. The as-synthesized RF resin coated nanocomposites are ideal candidates for selective synthesis of core-shell, hollow, and yolk-shell carbon nanostructures. Based on the carboxylic functional RF resin coating, graphitic carbon nanostructures can also be synthesized by employing the graphitization catalyst. The as-synthesized carbon nanostructures show the advantageous performances in several applications. Hollow carbon spheres are potential electrode materials for lithium-sulfur batteries. Hollow graphitic

  5. Formaldehyde sensor using non-dispersive UV spectroscopy at 340nm

    NASA Astrophysics Data System (ADS)

    Davenport, J. J.; Hodgkinson, J.; Saffell, J. R.; Tatam, R. P.

    2014-05-01

    Formaldehyde is a volatile organic compound that exists as a gas at room temperature. It is hazardous to human health causing irritation of the eyes, nose and throat, headaches, limited pulmonary function and is a potential human carcinogen. Sources include incomplete combustion, numerous modern building materials and vehicle fumes. Here we describe a simple method for detecting formaldehyde using low resolution non-dispersive UV absorption spectroscopy for the first time. A two channel system has been developed, making use of a strong absorption peak at 339nm and a neighbouring region of negligible absorption at 336nm as a reference. Using a modulated UV LED as a light source and narrowband filters to select the desired spectral bands, a simple detection system was constructed that was specifically targeted at formaldehyde. A minimum detectable absorbance of 4.5 × 10-5 AU was estimated (as ΔI/I0), corresponding to a limit of detection of approximately 6.6 ppm for a 195mm gas cell, with a response time of 20s. However, thermally-induced drift in the LED spectral output caused this to deteriorate over longer time periods to around 30 ppm or 2 × 10-4 AU.

  6. Hybridized doxorubicin-Au nanospheres exhibit enhanced near-infrared surface plasmon absorption for photothermal therapy applications

    NASA Astrophysics Data System (ADS)

    Zhou, Jialin; Wang, Zuhua; Li, Qingpo; Liu, Fei; Du, Yongzhong; Yuan, Hong; Hu, Fuqiang; Wei, Yinghui; You, Jian

    2015-03-01

    Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold nanospheres by synthesizing hybridized DOX-Au nanospheres (DAuNS), where a part of the DOX molecules and Au co-formed a hybridized matrix as the shell and the remaining DOX molecules precipitated as the core. The unique structure of DAuNS induced interesting changes in the characteristics including spectrum properties, morphology, drug loading and antitumor activity. We observed that DAuNS exhibited a significantly enhanced surface plasmon absorption in the NIR region, inducing a more efficient photothermal conversion and stronger tumor-cell killing ability under NIR laser irradiation. In addition, our study presents a new and simple platform to load a drug into nanoparticles. DAuNS could be a promising nanoparticle with the ``two punch'' efficacy of PTT and chemotherapy and could be used in clinical applications due to its controllable synthesis, small size, and narrow size distribution.Photothermal therapy (PTT) employs photosensitizing agents, which are taken up by cells and generate heat when irradiated with near-infrared (NIR) light, to enable the photoablation of cancer cells. High absorption in the NIR region is crucial for a photosensitizing agent to achieve efficient PTT. Different combinations between gold nanoparticles and fluorescent agents always influence their spectrum properties. Herein, we fabricated a novel combination of a fluorescent agent (doxorubicin, DOX, also a popular chemotherapeutic agent) with gold

  7. Formation of core-shell Au@Ag nanorods induced by catecholamines: A comparative study and an analytical application.

    PubMed

    Gorbunova, M V; Apyari, V V; Dmitrienko, S G; Garshev, A V

    2016-09-14

    Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were synthesized and an interaction of catecholamines (CAs) with silver ions in the presence of the obtained AuNRs was studied. The reaction results into formation of core-shell Au@Ag nanorods (Au@AgNRs) and leads to a hypsochromic shift of the long-wave surface plasmon resonance (SPR) band in the absorption spectrum of AuNRs. The influence of a CA structure, excess of CTAB, interaction time, pH, concentration of AuNRs, silver ions and CAs on this interaction was studied. Based on correlation of the NRs spectral characteristics with the concentration of CAs, a method for spectrophotometric determination of dobutamine, epinephrine, norepinephrine and dopamine with detection limits 27, 18, 16 and 13 μg L(-1), respectively, has been developed. The method can be applied to the analysis of medicines. PMID:27566354

  8. EFFECTS OF FORMALDEHYDE AND PARTICLE-BOUND FORMALDEHYDE ON LUNG MACROPHAGE FUNCTIONS

    EPA Science Inventory

    Dr. George Jakab and associates exposed mice to varying levels (ranging from 0.5 to 15 parts per million [ppm]) of formaldehyde alone or to formaldehyde (5 and 2.5 ppm) mixed with carbon black particles. Carbon black particles were chosen because of their similarity to comb...

  9. Rapid synthesis and characterization of hybrid ZnO@Au core-shell nanorods for high performance, low temperature NO2 gas sensor applications

    NASA Astrophysics Data System (ADS)

    Ponnuvelu, Dinesh Veeran; Pullithadathil, Biji; Prasad, Arun K.; Dhara, Sandip; Ashok, Anuradha; Mohamed, Kamruddin; Tyagi, Ashok Kumar; Raj, Baldev

    2015-11-01

    A rapid synthesis route for hybrid ZnO@Au core-shell nanorods has been realized for ultrasensitive, trace-level NO2 gas sensor applications. ZnO nanorods and hybrid ZnO@Au core-shell nanorods are structurally analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Optical characterization using UV-visible (UV-vis), photoluminescence (PL) and Raman spectroscopies elucidate alteration in the percentage of defect and charge transport properties of ZnO@Au core-shell nanorods. The study reveals the accumulation of electrons at metal-semiconductor junctions leading to upward band bending for ZnO and thus favors direct electron transfer from ZnO to Au nanoclusters, which mitigates charge carrier recombination process. The operating temperature of ZnO@Au core-shell nanorods based sensor significantly decreased to 150 °C compared to alternate NO2 sensors (300 °C). Moreover, a linear sensor response in the range of 0.5-5 ppm of NO2 concentration was observed with a lowest detection limit of 500 ppb using conventional electrodes. The defects with deep level, observed in ZnO nanorods and hybrid ZnO@Au core-shell nanorods influences local electron density, which in-turn indirectly influence the gas sensing properties. The ZnO@Au core-shell nanorods based sensor exhibited good selectivity toward NO2 and was found to be very stable.

  10. Formaldehyde as hypothetical primer of biohomochirality

    NASA Astrophysics Data System (ADS)

    Goldanskii, Vitalii I.

    1996-07-01

    One of the most intriguing and crucial problems of the prebiotic evolution and the origin of life is the explanation of the origin of biohomochirality. A scheme of conversions originated by formaldehyde (FA) as hypothetical primer of biohomochirality is proposed. The merit of FA as executor of this function is based -inter alia - on the distinguished role of FA as one of the earliest and simplest molecules in both warm, terrestrial and cold, extraterrestrial scenarios of the origin of life. The confirmation of the role of FA as primer of biohomochirality would support the option of an RNA world as an alternative to the protein world. The suggested hypothesis puts forward for the first time a concrete sequence of chemical reactions which can lead to biohomochirality. The spontaneous breaking of the mirror symmetry is secured by the application of the well-known Frank scheme (combination of autocatalysis and ``annihilation'' of L and D enantiomers) to the series of interactions of FA ``trimers'' (i.e. C3H6O3 compounds) of (aaa), (apa) and (app) types, where the monomeric groups (a) means ``achirons'' (a=CHn, n>=2 and C=M, M=C,O) and (p) mean ``prochirons'' (p=HC*OM, M=H,C).

  11. Graphene decorated with PtAu alloy nanoparticles: facile synthesis and promising application for formic acid oxidation

    SciTech Connect

    Zhang, Sheng; Shao, Yuyan; Liao, Honggang; Liu, Jun; Aksay, Ilhan A.; Yin, Geping; Lin, Yuehe

    2011-03-01

    PtAu alloy nanoparticles (~ 3.2 nm in diameter) are synthesized in poly(diallyldimethylammonium chloride) (PDDA) aqueous solution and uniformly dispersed on graphene nanosheets. PtAu/graphene exhibits high electrocatalytic activity and stability for formic acid oxidation, which is attributed to the high dispersion of PtAu nanoparticles and the specific interaction between PtAu and graphene, indicating a promising catalyst for direct formic acid fuel cells. The facile method can be readily extended to the synthesis of other alloy nanoparticles.

  12. Fabrication of hierarchical core-shell Au@ZnO heteroarchitectures initiated by heteroseed assembly for photocatalytic applications.

    PubMed

    Qin, Yao; Zhou, Yanjie; Li, Jie; Ma, Jie; Shi, Donglu; Chen, Junhong; Yang, Jinhu

    2014-03-15

    Three dimensional dandelion-like hierarchical core-shell Au@ZnO heteroarchitectures with ZnO nanorods grown radially on Au nanoparticle (NP) cores have been successfully prepared with a high yield via a simple solution method involving heteroseed-induced nucleation and subsequent heteroepitaxial growth processes. Briefly, mercaptopropionic acid (MA) modified Au NPs were synthesized beforehand and served as nucleation centers for primary ZnO seed generation and Au@ZnO heteroseed formation. Then an epitaxial growth of ZnO nanorods (ZnO NRs) on the Au@ZnO heteroseeds resulted in the formation of Au@ZnO dandelions. The photocatalytic properties of as-prepared Au@ZnO dandelions were evaluated through rhodamine B (RhB) photodegradation under UV irradiation. The result showed that the Au@ZnO dandelions had improved photocatalytic performance compared with pure ZnO NRs and hybrids of ZnO NRs/Au NPs, due likely to the synergistic effect of the metal-semiconductor heterojunction and the unique dandelion-like hierarchical core-shell structure. PMID:24461832

  13. Formaldehyde OMI operational retrieval upgrades

    NASA Astrophysics Data System (ADS)

    Gonzalez Abad, G.; Chance, K.; Liu, X.

    2013-05-01

    Total column of formaldehyde (HCHO), a proxy for biogenic emissions, can be observed from satellites using the ultraviolet region of the spectrum. The operational HCHO retrievals from the Ozone Monitoring Instrument (OMI) on board the AURA satellite, part of NASA's A-train constellation of Earth Observing satellites, are described. The operational retrieval, based on a basic optical absorption spectroscopy (BOAS) algorithm, has been affected by the degradation of the instrument especially from 2008 onwards. The most significant problems are the unrealistic increasing high background concentrations of HCHO retrieved from OMI and the row anomaly. An upgrade for the original operational algorithm is therefore needed to ensure its trend quality and to account for these difficulties. The strategies implemented to deal with the instrumental degradation are presented here. Air mass factors (AMFs) in the current fitting window show significant wavelength dependence. Fitting uncertainties can potentially be improved by including shorter wavelengths as long as the AMFs wavelength dependence is taken into account. As part of these improvements a look-up table of wavelength-dependent AMFs have been calculated. Using this new table it is possible to retrieve the HCHO total column directly, weighting the HCHO cross sections with the wavelength-dependent AMFs. Additionally, the pixels affected by the row anomaly are now flagged in the level 2 data generated with the upgraded algorithm.

  14. Formaldehyde absorption toward W51

    NASA Technical Reports Server (NTRS)

    Kogut, A.; Smoot, G. F.; Bennett, C. L.; Petuchowski, S. J.

    1989-01-01

    Formaldehyde (H2CO) absorption toward the H II region complex W51A (G49.5 - 0.4) in the 6 cm and 2 cm wavelength rotational transitions has been measured with angular resolution of about 0.15 pc. The continuum H II region shows a large, previously undetected shell structure 5.5 pc along the major axis. The absorption, converted to optical depth, shows a higher degree of clumping throughout the map than previous maps at lower resolution; in particular, two narrow regions of enhanced opacity are observed. The absorption in the velocity range 64-67 km/s LSR extends over most of the region, with an observed velocity gradient of 5.2 km/s pc. The opacity structure largely parallels the velocity structure, with a ridge of enhanced opacity to the north of the highest velocity feature. The S/N of the maps allows accurate modeling of the spectral profiles. Nine distinct clumps in the foreground clouds have been identified and parametrized, and column densities for the 1(11) and 2(12) rotational levels of orthoformaldehyde have been derived.

  15. One-Pot Synthesis of Monodisperse Noble Metal @ Resorcinol-Formaldehyde (M@RF) and M@Carbon Core-Shell Nanostructure and Their Catalytic Applications.

    PubMed

    Yang, Peipei; Xu, Yong; Chen, Lei; Wang, Xuchun; Zhang, Qiao

    2015-10-27

    We demonstrate that noble metal @ RF core-shell nanostructures can be obtained through a facile one-pot synthesis approach in the absence of any additional surfactants. Monodisperse metal@RF core-shell nanostructures can be produced within 1 h on a large scale. Both the core size and shell thickness can be readily tuned by altering the reaction parameters. Systematic studies reveal that resorcinol could have several functions: it could act as a reactant to form RF resin, and it also could passivate the surface of metallic nanoparticles to prevent them from aggregating. Additionally, for the first time, our results suggest that resorcinol may act as a reducing agent that can reduce metal salts to form metal nanoparticles. The core-shell nanoparticles can be carbonized into M@carbon nanostructures, which have shown great performance in the catalytic hydrogenation of chlorobenzene. This work not only will help to achieve the controllable synthesis of noble metal@RF resin and M@carbon core-shell nanostructures but also will promote research into other RF-based nanostructures and their catalytic applications. PMID:26434608

  16. Design of highly sensitive and selective Au@NiO yolk-shell nanoreactors for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Rai, Prabhakar; Yoon, Ji-Wook; Jeong, Hyun-Mook; Hwang, Su-Jin; Kwak, Chang-Hoon; Lee, Jong-Heun

    2014-06-01

    Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H2S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH3, CO and H2). The maximum response was 108.92 for 5 ppm of H2S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H2S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H2S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response.Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H2S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH3, CO and H2). The maximum response was 108.92 for 5 ppm

  17. Evidence for chemical and cellular reactivities of the formaldehyde releaser bronopol, independent of formaldehyde release.

    PubMed

    Kireche, Mustapha; Peiffer, Jean-Luc; Antonios, Diane; Fabre, Isabelle; Giménez-Arnau, Elena; Pallardy, Marc; Lepoittevin, Jean-Pierre; Ourlin, Jean-Claude

    2011-12-19

    Formaldehyde and formaldehyde releasers are widely used preservatives and represent an important group of skin sensitizers. Formaldehyde is very often suspected to be the sensitizing agent of formaldehyde-releasers; however, many reported clinical cases of contact allergy to these molecules such as bronopol (2-bromo-2-nitropropane-1,3-diol) indicate negative skin reactions to formaldehyde suggesting a more complex mechanism. The aim of this study was to compare the chemical reactivity and biological activity of formaldehyde with those of two formaldehyde releasers: 2-bromo-2-nitropropane-1,3-diol and 1,3-dimethylol-5,5-dimethylhydantoin. A key step in the sensitization to chemicals is the formation of the hapten-protein antigenic complex via covalent binding between the chemical sensitizer and amino acids in proteins. The chemical reactivity of the three compounds was thus addressed using (13)C NMR analysis of adduct formation upon incubation with a set of nucleophilic amino acids. The biological activity was measured in two in vitro models based on dendritic cells and a monocytic cell line (CD34-DC and THP-1 model) through monitoring of a panel of biomarkers. The results obtained show that 2-bromo-2-nitropropane-1,3-diol produces low amount of free formaldehyde in physiological buffers but that its degradation generates various molecules including 2-bromoethanol. In addition, 2-bromo-2-nitropropane-1,3-diol also generates adducts with amino acids, not observed with formaldehyde alone, that could be explained by the reactivity of 2-bromoethanol. In parallel, in a cellular approach using the human monocytic THP-1 cell line, 2-bromo-2-nitropropane-1,3-diol activates THP-1 cells at concentrations that are not correlated to simple formaldehyde release. This observation is confirmed in the more physiological model CD34-DC. Moreover, in the THP-1 model, the expression profiles of several biomarkers are specific to 2-bromo-2-nitropropane-1,3-diol. Finally, the use in the

  18. Synthesis and characterization of Cu2O/Au and its application in catalytic reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Guo, X. H.; Ma, J. Q.; Ge, H. G.

    2015-08-01

    Monodispersed Cu2O spherical colloids with diameter of about 300 nm were prepared by a facile additive-assisted complex-precursor solution method. Core-shell structure Cu2O/Au composites, constructed by spherical Cu2O core and Au nanoparticles shell, were obtained via galvanic replacement method. The morphology, microstructure and optical properties of the Cu2O/Au composites were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectra and ultraviolet-visible absorption. The results showed that Au NPs with an average size of 12 nm were uniformly distributed on the surface of the Cu2O spheres with size about 300 nm. Cu2O/Au composites exhibit high catalytic activity toward 4-NP reduction at room temperature.

  19. Naphthalimide derived fluorescent probes with turn-on response for Au(3+) and the application for biological visualization.

    PubMed

    Li, Yan; Qiu, Yanxin; Zhang, Jianjian; Zhu, Xinyue; Zhu, Bin; Liu, Xiaoyan; Zhang, Xiaoyu; Zhang, Haixia

    2016-09-15

    The 4-N,N-dimethyl-1,8-naphthalimide based fluorescent probes have been explored for selective detection of Au(3+). Both probes show a pronounced fluorescence enhancement response to Au(3+). Hydroxy is introduced as ligand of Au(3+) for Probe 1 and the newly designed Probe 2 contains an alkyne moiety to recognize Au(3+) through an irreversible C≡C bond hydrolysis reaction. Probe 1 exhibits higher performance such as faster response, lower detection limit of 0.050μM and the better responsive effect in 99.5% water system compared with most of probes published. The Probe 2 displays high stability to pH, suitable water solubility, wider linear range (0-100μM) to Au(3+), and live-cells imaging with low cytotoxicity. PMID:27135938

  20. Comparison of two formaldehyde administration methods of in ovo-injected eggs.

    PubMed

    Steinlage, Sara J Throne; Sander, Jean E; Wilson, Jeanna L

    2002-01-01

    Formaldehyde administration in the hatchery can be very useful in decreasing microbial numbers. However, its use is controversial because of the adverse effects that can occur to chicks and people. This study was designed to look at alternative methods of application of formaldehyde in the hatchery. In addition, the study compared the effects of these methods of application on in ovo-and non-in ovo-injected eggs. All in ovo-injected eggs were given diluent only with no vaccine or antibiotic added. In hatchers containing both in ovo-injected eggs and non-in ovo-injected eggs, formaldehyde was administered two ways, dose (DOSE) and constant rate infusion (CRI). In the DOSE hatcher, 12 ml of formaldehyde was administered at one time every 12 hr, whereas in the CRI hatcher, the same volume was administered at a rate of 1 ml/hr over a 12-hr period. A control (CONT) hatcher received 12 ml of distilled water at the same time that the DOSE hatcher was given formaldehyde. In the DOSE hatcher, a peak concentration of formaldehyde of 102 ppm was reached. The CRI was maintained at approximately 20 ppm of formaldehyde. At pipping, the aerosol bacterial load in the hatchers receiving formaldehyde (DOSE, 130 colony-forming units [CFU]/m3; CRI, 82.5 CFU/m3) was significantly less than in the CONT hatcher (235 CFU/m3). At hatch, the CRI (337.5 CFU/m3) was not able to control bacterial levels and only the DOSE hatcher (150 CFU/m3) had a significantly lower aerosol bacterial count. The CRI non-in ovo-injected eggs (93.39%) had a significantly higher percentage of hatch of fertile compared with non-in ovo-injected eggs exposed to water (84.27%). In ovo-injected eggs in CONT and DOSE treatment groups contained significantly higher percentages of visual contamination than non-in on-injected eggs in the same hatchers. This difference had numerical significance only in the treatment groups within the CRI hatcher. The chicks were then placed into replicate treatment groups and grown for 14

  1. Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe3O4 nanocomposites as a promising, nontoxic system for biomedical applications

    PubMed Central

    Kashanian, Soheila

    2015-01-01

    Summary The unique properties and applications of iron oxide and Au nanoparticles have motivated researchers to synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core–shell structures (such as reduced saturation magnetization and thick coating) have been overcome. In the present study, chitosan and one of its well-known derivatives, N-trimethylchitosan (TMC), were applied to construct three-layer nanocomposites in an Au/polymer/Fe3O4 system. It was demonstrated that replacement of chitosan with TMC reasonably improved the properties of the final nanocomposites including their size, magnetic behavior and thermal stability. Moreover, the results of the MTT assay showed no significant cytotoxicity effect when the Au/TMC/Fe3O4 nanocomposites were applied in vitro. These TMC-containing magnetic nanoparticles are well-coated by Au nanoparticles and have good biocompatibility and can thus play the role of a platform or a label in various fields of application, especially the biomedical sciences and biosensors. PMID:26425418

  2. Formaldehyde content of atmospheric aerosol.

    PubMed

    Toda, Kei; Yunoki, Satoru; Yanaga, Akira; Takeuchi, Masaki; Ohira, Shin-Ichi; Dasgupta, Purnendu K

    2014-06-17

    Formaldehyde (HCHO) is a highly soluble polar molecule with a large sticking coefficient and thus likely exists in both gaseous and particulate forms. Few studies, however, address particulate HCHO (HCHO(p)). Some report that HCHO(p) concentrations (obtained only with long duration sampling) are very low. The lack of data partly reflects the difficulty of specifically measuring HCHO(p). Long duration filter sampling may not produce meaningful results for a variety of reasons. In this work, gaseous HCHO (HCHO(g)) and (HCHO(p)) were, respectively, collected with a parallel plate wet denuder (PPWD) followed by a mist chamber/hydrophilic filter particle collector (PC). The PPWD quantitatively removed HCHO(g) and the PC then collected the transmitted aerosol. The collected HCHO from either device was alternately analyzed by Hantzsch reaction-based continuous flow fluorometry. Each gas and particle phase measurement took 5 min each, with a 10 min cycle. The limits of detection were 0.048 and 0.0033 μg m(-3), respectively, for HCHO(g) and HCHO(p). The instrument was deployed in three separate campaigns in a forest station in western Japan in March, May, and July of 2013. Based on 1296 data pairs, HCHO(p), was on the average, 5% of the total HCHO. Strong diurnal patterns were observed, with the HCHO(p) fraction peaking in the morning. The relative humidity dependence of the partition strongly suggests that it is driven by the liquid water content of the aerosol phase. However, HCHO(p) was 100× greater than that expected from Henry's law. We propose that the low water activity in the highly saline droplets lead to HCHO oligomerization. PMID:24857706

  3. Production of Melamine-Formaldehyde PCM Microcapsules with Ammonia Scavenger used for Residual Formaldehyde Reduction.

    PubMed

    Sumiga, Boštjan; Knez, Emil; Vrtačnik, Margareta; Ferk-Savec, Vesna; Starešinič, Marica; Boh, Bojana

    2011-03-01

    Paraffinic phase change materials (PCM) were microencapsulated by in situ polymerization of melamine-formaldehyde prepolymers. Partly methylated trimethylolmelamine was used as an aminoaldehyde prepolymer for the microcapsule wall, a styrene-maleic acid anhydride copolymer as an emulsifier and modifying agent, and ammonia as a scavenger for reducing residual formaldehyde. For the determination of residual formaldehyde in a ppm concentration range, EDANA and malachite green analytical methods were studied, and the EDANA 210.1-99 was applied for the determination of residual formaldehyde in 25 samples of microcapsules, produced in a 200-L reactor. A linear correlation was observed between the added ammonia scavenger concentration and the reduction of residual formaldehyde concentration. Compared with 0.45% (4500 ppm) formaldehyde in a non-treated microcapsule suspension, with ammonia scavenger concentrations 0.80, 0.90 and 1.35%, the concentration of residual formaldehyde dropped to 0.27, 0.20 and 0.09% (i.e. 2700, 2000 and 900 ppm), respectively. Morphological characterisation of microcapsules by SEM and microcapsule wall permeability measurements by gravimetry / mass loss at an elevated temperature (135 °C) suggested that ammonia positively contributed to the wall elasticity / durability, while microcapsules with no ammonia scavenger added tended to have more brittle walls, and were more prone to cracking. PMID:24061938

  4. Evaluation of possible health risk associated with occupational exposure to formaldehyde

    NASA Astrophysics Data System (ADS)

    Vargova, Maria; Janota, Stanislav; Karelova, Jarmila; Barancokova, Maria; Sulcova, Margita

    1993-03-01

    Widespread us of formaldehyde in a variety of applications is known to result in appreciable exposure of workers and large segments of the general population. Because of possible genotoxic and immunotoxic effects, we investigated the health condition of people occupationally exposed to formaldehyde in a plant in which woodsplinter materials are manufactured. The concentration of formaldehyde in the workplace was greater than the average and peak concentrations of formaldehyde in Czechoslovakia (0.5 mg/m3 and 1 mg/m3 respectively). Selected parameters of genotoxicity (cytogenetic analysis, nucleolus test) and immunotoxocity (serum immunoglobulin G, A, M; complement C3, C4; alpha-1-anti-trypsine, alpha-2 macroglobulin, ceruloplasmin, transferrin, prealbumin, orosomucoid levels) were determined. The results of the evaluation of mitotic indices and the blastogen transformation point to an effect of the exposure to formaldehyde on r-RNA synthesis inhibition and lymphocyte maturation decrease. The frequency of aberrant cells in the peripheral blood lymphocytes was increased in both, exposed and control group and was above 1.2 - 2% of aberrant cells observed in the normal population in Czechoslovakia. There was no significant differences in the values of natural immunity and specific humoral immunity. Significant differences were observed in the values of mitogen-induced proliferation of lymphocytes between the exposed and the matching and background control groups. These changes are considered to be sensitive indicators of the potential effects on the integrity of a more important immunologic function.

  5. Formation of formaldehyde and peroxides by air oxidation of high purity polyoxyethylene surfactants.

    PubMed

    Bergh, M; Magnusson, K; Nilsson, J L; Karlberg, A T

    1998-07-01

    Ethoxylated alcohols are non-ionic surfactants. The majority are used in household cleaners, laundry products, toiletries and in industrial and institutional cleaners. In previous studies, an ethoxylated non-ionic surfactant of technical quality showed allergenic activity in guinea pig experiments. Chemical analysis revealed a content of formaldehyde, a well-known contact allergen, and peroxides in the surfactant. Most cases of occupational contact dermatitis are considered to be of irritant origin, caused by contact with water and surfactants, but if allergenic autoxidation products can be formed, allergic contact dermatitis cannot be excluded. The sensitizing potential of a chemically defined high purity ethoxylated alcohol was investigated and oxidation under various storage and handling conditions was studied for this and a homologous product. The pure surfactant showed no significant allergenic activity on predictive testing in guinea pigs. When ethoxylated alcohols were stored in the refrigerator, their deterioration was limited. At room temperature, their content of peroxides and formaldehyde increased with time. Levels of formaldehyde above those capable of causing positive patch test reactions were found. Since such surfactants have wide applications, resulting exposure to formaldehyde could be more frequent than is generally realized, contributing to persistence of dermatitis in individuals allergic to formaldehyde. PMID:9686972

  6. Exposure to formaldehyde: effects of pulmonary function

    SciTech Connect

    Alexandersson, R.; Kolmodin-Hedman, B.; Hedenstierna, G.

    1982-09-01

    Forty-seven subjects exposed to formaldehyde (mean air concentration 0.45 mg/m/sup 3/) and 20 unexposed subjects, all of whom were employed at a carpentry shop, were studied with regard to symptoms and pulmonary function. Symptoms involving eyes and throat as well as chest oppression were significantly more common in the exposed subjects than in the unexposed controls. Spirometry and single breath nitrogen washout were normal Monday morning before exposure to formaldehyde. A reduction in forced expiratory volume in 1 sec by an average of 0.2 L (P = .002), percent forced expiratory volume by 2% (P = .04), maximum midexpiratory flow by 0.3 L/sec (P = .04) and an increase in closing volume in percentage of vital capacity by 3.4% (P = .002) were seen after a day of work and exposure to formaldehyde, suggesting bronchoconstriction. Smokers and nonsmokers displayed similar changes in spirometry and nitrogen washout.

  7. Porous Nickel Oxide Film Sensor for Formaldehyde

    NASA Astrophysics Data System (ADS)

    Cindemir, U.; Topalian, Z.; Österlund, L.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    Formaldehyde is a volatile organic compound and a harmful indoor pollutant contributing to the "sick building syndrome". We used advanced gas deposition to fabricate highly porous nickel oxide (NiO) thin films for formaldehyde sensing. The films were deposited on Al2O3 substrates with prefabricated comb-structured electrodes and a resistive heater at the opposite face. The morphology and structure of the films were investigated with scanning electron microscopy and X-ray diffraction. Porosity was determined by nitrogen adsorption isotherms with the Brunauer-Emmett-Teller method. Gas sensing measurements were performed to demonstrate the resistive response of the sensors with respect to different concentrations of formaldehyde at 150 °C.

  8. Self-Sufficient Formaldehyde-to-Methanol Conversion by Organometallic Formaldehyde Dismutase Mimic.

    PubMed

    van der Waals, Dominic; Heim, Leo E; Vallazza, Simona; Gedig, Christian; Deska, Jan; Prechtl, Martin H G

    2016-08-01

    The catalytic networks of methylotrophic organisms, featuring redox enzymes for the activation of one-carbon moieties, can serve as great inspiration in the development of novel homogeneously catalyzed pathways for the interconversion of C1 molecules at ambient conditions. An imidazolium-tagged arene-ruthenium complex was identified as an effective functional mimic of the bacterial formaldehyde dismutase, which provides a new and highly selective route for the conversion of formaldehyde to methanol in absence of any external reducing agents. Moreover, secondary amines are reductively methylated by the organometallic dismutase mimic in a redox self-sufficient manner with formaldehyde acting both as carbon source and reducing agent. PMID:27380865

  9. The effect of clothing care activities on textile formaldehyde content.

    PubMed

    Novick, Rachel M; Nelson, Mindy L; McKinley, Meg A; Anderson, Grace L; Keenan, James J

    2013-01-01

    Textiles are commonly treated with formaldehyde-based residues that may potentially induce allergic contact dermatitis in sensitive individuals. This study examined the initial formaldehyde content in clothing and resulting changes due to care activities. Twenty clothing articles were examined and 17 of them did not have detectable levels of formaldehyde. One shirt contained a formaldehyde concentration of 3172 ppm, and two pairs of pants had formaldehyde concentrations of 1391 ppm and 86 ppm. The two highest results represent formaldehyde levels that are up to 40-fold greater than international textile regulations. The two items with the greatest formaldehyde content were washed and dried in a manner similar to that used by consumers, including hand and machine washing in hot or cold water followed by air or machine drying. The washing and drying procedures reduced formaldehyde levels to between 26 and 72% of untreated controls. Differences in the temperature or type of washing and drying did not result in a clear trend in the subsequent formaldehyde content. In addition, samples were hot ironed, which did not affect the formaldehyde content as significantly. Understanding the formaldehyde content in clothing and its potential reduction through care activities may be useful for manufacturers and formaldehyde-sensitive individuals. PMID:24053365

  10. STATUS OF IODINE IN FORMALDEHYDE-PRESERVED MILK - REVISITED

    EPA Science Inventory

    The effect of formaldehyde as a preservative for milk prior to radiochemical analysis for 131I was studied. Results suggest that the formaldehyde concentration is critical and that at low formaldehyde concentrations (<0.5 M) significant protein binding of iodine occurs. Various a...

  11. 24 CFR 3280.309 - Health Notice on formaldehyde emissions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Health Notice on formaldehyde... Construction Requirements § 3280.309 Health Notice on formaldehyde emissions. (a) Each manufactured home shall have a Health Notice on formaldehyde emissions prominently displayed in a temporary manner in...

  12. Developing a Reference Material for Formaldehyde Emissions Testing; Final Report

    EPA Science Inventory

    Exposure to formaldehyde has been shown to produce broad and potentially severe adverse human health effects. With ubiquitous formaldehyde sources in the indoor environment, formaldehyde concentrations in indoor air are usually higher than outdoors, ranging from 10 to 4000 μg/m3....

  13. Chemical Characterization of Phenol/Formaldehyde Resins

    NASA Technical Reports Server (NTRS)

    Brayden, T. H.

    1986-01-01

    Report discusses tests of commercial phenol/formaldehyde resins to establish relationships among composition before use, behavior during curing, and strength after curing. Resin used in carbon/carbon laminates. In curing process, two molecules of phenol joined together in sequence of reactions involving molecule of formaldehyde. Last step of sequence, molecule of water released. Sequence repeats until one of ingredients used up, leaving solidified thermoset plastic. Issues to be resolved: number and relative abundances of ingredients, presence of certain chemical groups, heat-producing ability of resin, and range of molecular weights present.

  14. DNA-templated synthesis of PtAu bimetallic nanoparticle/graphene nanocomposites and their application in glucose biosensor

    NASA Astrophysics Data System (ADS)

    Leng, Jing; Wang, Wen-Min; Lu, Li-Min; Bai, Ling; Qiu, Xin-Lan

    2014-02-01

    In this paper, single-stranded DNA (ss-DNA) is demonstrated to functionalize graphene (GR) and to further guide the growth of PtAu bimetallic nanoparticles (PtAuNPs) on GR with high densities and dispersion. The obtained nanocomposites (PtAuNPs/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), and electrochemical techniques. Then, an enzyme nanoassembly was prepared by self-assembling glucose oxidase (GOD) on PtAuNP/ss-DNA/GR nanocomposites (GOD/PtAuNPs/ss-DNA/GR). The nanocomposites provided a suitable microenvironment for GOD to retain its biological activity. The direct and reversible electron transfer process between the active site of GOD and the modified electrode was realized without any extra electron mediator. Thus, the prepared GOD/PtAuNP/ss-DNA/GR electrode was proposed as a biosensor for the quantification of glucose. The effects of pH, applied potential, and temperature on the performance of the biosensor were discussed in detail and were optimized. Under optimal conditions, the biosensor showed a linearity with glucose concentration in the range of 1.0 to 1,800 μM with a detection limit of 0.3 μM (S/N = 3). The results demonstrate that the developed approach provides a promising strategy to improve the sensitivity and enzyme activity of electrochemical biosensors.

  15. An enhanced photocatalytic response of nanometric TiO2 wrapping of Au nanoparticles for eco-friendly water applications

    NASA Astrophysics Data System (ADS)

    Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Brundo, Maria V.; Bergum, Kristin; Zimbone, Massimo; Sanz, Ruy; Buccheri, Maria A.; Simone, Francesca; Nicotra, Giuseppe; Svensson, Bengt G.; Grimaldi, Maria G.; Privitera, Vittorio

    2014-09-01

    We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (~8 nm mean diameter) with a thin layer of TiO2 (~4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

  16. DNA-templated synthesis of PtAu bimetallic nanoparticle/graphene nanocomposites and their application in glucose biosensor

    PubMed Central

    2014-01-01

    In this paper, single-stranded DNA (ss-DNA) is demonstrated to functionalize graphene (GR) and to further guide the growth of PtAu bimetallic nanoparticles (PtAuNPs) on GR with high densities and dispersion. The obtained nanocomposites (PtAuNPs/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), and electrochemical techniques. Then, an enzyme nanoassembly was prepared by self-assembling glucose oxidase (GOD) on PtAuNP/ss-DNA/GR nanocomposites (GOD/PtAuNPs/ss-DNA/GR). The nanocomposites provided a suitable microenvironment for GOD to retain its biological activity. The direct and reversible electron transfer process between the active site of GOD and the modified electrode was realized without any extra electron mediator. Thus, the prepared GOD/PtAuNP/ss-DNA/GR electrode was proposed as a biosensor for the quantification of glucose. The effects of pH, applied potential, and temperature on the performance of the biosensor were discussed in detail and were optimized. Under optimal conditions, the biosensor showed a linearity with glucose concentration in the range of 1.0 to 1,800 μM with a detection limit of 0.3 μM (S/N = 3). The results demonstrate that the developed approach provides a promising strategy to improve the sensitivity and enzyme activity of electrochemical biosensors. PMID:24572068

  17. Non-centrosymmetric Au-SnO2 hybrid nanostructures with strong localization of plasmonic for enhanced photocatalysis application.

    PubMed

    Wu, Wei; Liao, Lei; Zhang, Shaofeng; Zhou, Juan; Xiao, Xiangheng; Ren, Feng; Sun, Lingling; Dai, Zhigao; Jiang, Changzhong

    2013-06-21

    We present an innovative approach to the production of sub-100 nm hollow Au-SnO2 hybrid nanospheres, employing a low-cost, surfactant-free and environmentally friendly solution-based route. The hollow hybrid nanostructures were synthesized using a seed-mediated hydrothermal method, which can be divided into two stages: (1) formation of multicore-shell Au@SnO2 nanoparticles (NPs) and (2) thermal diffusion and ripening to form hollow Au-SnO2 hybrid NPs. The morphology, optical properties and formation mechanism were determined by a collection of joint techniques. Photocatalytic degradation of Rhodamine B (RhB) in the liquid phase served as a probe reaction to evaluate the activity of the as-prepared hollow hybrid Au-SnO2 NPs under the irradiation of both visible light and ultraviolet light. Significantly, the as-obtained Au-SnO2 hybrid nanostructures exhibited enhanced visible light or UV photocatalytic abilities, remarkably superior to commercial pure SnO2 products and P25 TiO2, mainly owing to the effective electron hole separation at the SnO2-Au interfaces and strong localization of plasmonic near-fields effects. PMID:23685533

  18. Unusual formaldehyde-induced hypersensitivity in two schoolgirls

    SciTech Connect

    Gammage, R.B. ); Hanna, W.T.; Painter, P.B. )

    1990-01-01

    Two schoolgirls developed a syndrome resembling Henoch-Schonlein purpura while attending a recently opened school insulated with urea-formaldehyde foam (UFFI). Skin rashes and swellings were accompanied by bizarre, blue-green discoloration of the skin. Subsequent investigations by county, state and federal authorities, and low measured concentrations of formaldehyde, prompted initial conclusions that in-school formaldehyde exposures were not responsible for the girls' problems. Subsequent controlled exposures to UFFI and formaldehyde while in hospital elicited the whole cascade of symptoms. The chronology of the onset and amplification of systems make it probable that the formaldehyde exposures precipitating the girls' hypersensitivity, occurred in the school. 3 refs.

  19. Optoelectrical Cooling of Formaldehyde to Sub-Millikelvin Temperatures

    NASA Astrophysics Data System (ADS)

    Zeppenfeld, Martin

    2016-05-01

    Due to their strong long-range dipole-dipole interactions and large number of internal states, polar molecules cooled to ultracold temperatures enable fascinating applications ranging from ultracold chemistry to investigation of dipolar quantum gases. However, realizing a simple and general technique to cool molecules to ultracold temperatures, akin to laser cooling of atoms, has been a formidable challenge. We present results for opto-electrical Sisyphus cooling applied to formaldehyde (H2 CO). In this generally applicable cooling scheme, molecules repeatedly move up and down electric field gradients of a trapping potential in different rotational states to efficiently extract kinetic energy. A total of about 300,000 molecules are thereby cooled by a factor of 1000 to 400uK, resulting in a record-large ensemble of ultracold molecules. In addition to cooling of the motional degrees of freedom, optical pumping via a vibrational transition allows us to control the internal rotational state. We thereby achieve a purity of over 80% of formaldehyde molecules in a single rotational M-sublevel. Our experiment provides an excellent starting point for precision spectroscopy and investigation of ultracold collisions.

  20. 29 CFR 1926.1148 - Formaldehyde.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Formaldehyde. 1926.1148 Section 1926.1148 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1148...

  1. 29 CFR 1926.1148 - Formaldehyde.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Formaldehyde. 1926.1148 Section 1926.1148 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1148...

  2. 29 CFR 1926.1148 - Formaldehyde.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Formaldehyde. 1926.1148 Section 1926.1148 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1148...

  3. 29 CFR 1926.1148 - Formaldehyde.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Formaldehyde. 1926.1148 Section 1926.1148 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1148...

  4. A passive sampler for airborne formaldehyde

    NASA Astrophysics Data System (ADS)

    Grosjean, Daniel; Williams, Edwin L.

    A simple, inexpensive passive sampler is described that is capable of reliable measurements of formaldehyde at the parts per billion (ppb) levels relevant to indoor and outdoor air quality. The passive sampler consists of a modified dual filter holder in which the upper stage serves as the diffusion barrier, the lower stage includes a 2,4-dinitrophenylhydrazine (DNPH)-coated filter which collects formaldehyde, and the space between the two stages serve as the diffusion gap. The measured sampling rate, 18.8 ± 1.8 ml min -1, was determined in experiments involving sampling of ppb levels of formaldehyde with the passive sampler and with DNPH-coated C 18 cartridges and agrees well with the value of 19.4 ± 2.0 ml min -1 calculated from theory. The measured sampling rate was independent of formaldehyde concentration (16-156 ppb) and sampling duration (1.5-72 h). The precision of the measurements for colocated passive samplers averaged 8.6% in purified and indoor air (office and museums) and 10.2% in photochemically polluted outdoor air. With a 1.2-μm pore size Teflon filter as the diffusion barrier, the detection limit is 32 ppb h, e.g. 4 ppb in an 8-h sample, 1.3 ppb in a 24-h sample, and so on. Perceived advantages and limitations of the sampler are discussed including flexibility, cost effectiveness and possible negative bias at high ambient levels of ozone.

  5. CHRONIC RESPIRATORY EFFECTS OF INDOOR FORMALDEHYDE EXPOSURE

    EPA Science Inventory

    The relation of chronic respiratory symptoms and pulmonary function to formaldehyde (HCHO) in homes was studied in a sample of 298 children (6 - 15 years of age) and 613 adults. CHO measurements were made with passive samplers two one-week periods. ata on chronic cough and phlegm...

  6. Gypsum Wallboard as a sink for formaldehyde

    EPA Science Inventory

    Formaldehyde (HCHO) has been of special concern as an indoor air pollutant because of its presence in a wide range of consumer products and its adverse health effects. Materials acting as HCHO sinks, such as painted gypsum wallboard, can become emission sources. However, adsorpti...

  7. Electrospinning formaldehyde cross-linked zein solutions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to develop zein fibers with improved physical properties and solvent resistance, formaldehyde was used as the cross-linking reagent before spinning. The cross-linking reaction was carried out in either acetic acid or ethanolic-HCl where the amount of cross-linking reagent was between 1 and...

  8. 29 CFR 1926.1148 - Formaldehyde.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Formaldehyde. 1926.1148 Section 1926.1148 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1148...

  9. Edible carbohydrates from formaldehyde in a spacecraft

    NASA Technical Reports Server (NTRS)

    Weiss, A. H.

    1975-01-01

    The autocatalytic nature of the base catalyzed condensation of formaldehyde to formose sugars is eliminated by using as a cocatalyst, an aldose, or ketose having an alpha-hydrogen. This is more strongly complexed by base than is formaldehyde and the cocatalyst and sugar products accumulate as catalyst complexes instead of formaldehyde. Because of the presence of alpha-hydrogen atoms in cocatalysts and formose sugars, their removal by cross Cannizzaro reaction of complexed sugars does not occur, so the formose reaction behaves autocatalytically due to this accumulation. It is believed that a given catalytic formose complex is not a discrete complexed sugar, but rather, a scrambled dynamic mixture of sugars having weakened structures. The sugar complexes derive from a common salt-like formaldehyde complex, which, because of the absence of alpha-hydrogen, has a greater tendency to undergo Cannizzaro reaction, rather than formose condensation. Because of this, the Cannizzaro reaction can proceed without measurable formose condensation. The reverse is not possible.

  10. Toxic effects of formaldehyde on the urinary system

    PubMed Central

    İnci, Mehmet; Zararsız, İsmail; Davarcı, Mürsel; Görür, Sadık

    2013-01-01

    Formaldehyde is a chemical substance with a pungent odor that is highly soluble in water and occurs naturally in organisms. Formaldehyde, when taken into organisms, is metabolized into formic acid in the liver and erythrocytes and is then excreted, either with the urine and feces or via the respiratory system. Form-aldehyde is widely used in the industrial and medical fields, and employees in these sectors are frequently exposed to it. Anatomists and medical students are affected by formaldehyde gas during dissection lessons. Because full protection from formaldehyde is impossible for employees in industrial plants using this chemical and for workers in laboratory conditions, several measures can be implemented to prevent and/or reduce the toxic effects of formaldehyde. In this review, we aimed to identify the toxic effects of formaldehyde on the urinary system. PMID:26328078

  11. Application de la methode des sous-groupes au calcul Monte-Carlo multigroupe

    NASA Astrophysics Data System (ADS)

    Martin, Nicolas

    This thesis is dedicated to the development of a Monte Carlo neutron transport solver based on the subgroup (or multiband) method. In this formalism, cross sections for resonant isotopes are represented in the form of probability tables on the whole energy spectrum. This study is intended in order to test and validate this approach in lattice physics and criticality-safety applications. The probability table method seems promising since it introduces an alternative computational way between the legacy continuous-energy representation and the multigroup method. In the first case, the amount of data invoked in continuous-energy Monte Carlo calculations can be very important and tend to slow down the overall computational time. In addition, this model preserves the quality of the physical laws present in the ENDF format. Due to its cheap computational cost, the multigroup Monte Carlo way is usually at the basis of production codes in criticality-safety studies. However, the use of a multigroup representation of the cross sections implies a preliminary calculation to take into account self-shielding effects for resonant isotopes. This is generally performed by deterministic lattice codes relying on the collision probability method. Using cross-section probability tables on the whole energy range permits to directly take into account self-shielding effects and can be employed in both lattice physics and criticality-safety calculations. Several aspects have been thoroughly studied: (1) The consistent computation of probability tables with a energy grid comprising only 295 or 361 groups. The CALENDF moment approach conducted to probability tables suitable for a Monte Carlo code. (2) The combination of the probability table sampling for the energy variable with the delta-tracking rejection technique for the space variable, and its impact on the overall efficiency of the proposed Monte Carlo algorithm. (3) The derivation of a model for taking into account anisotropic

  12. Photoinduced ultrafast charge separation in colloidal 2-dimensional CdSe/CdS-Au hybrid nanoplatelets and corresponding application in photocatalysis.

    PubMed

    Chauhan, Himani; Kumar, Yogesh; Dana, Jayanta; Satpati, Biswarup; Ghosh, Hirendra N; Deka, Sasanka

    2016-08-25

    Multicomponent hybrid nanocrystals (HNC) consisting of a semiconductor and metallic domains are an important class of nanostructured materials demonstrating useful applications and interesting basic knowledge. In this scenario, Au nanoparticle (NP) islands of ∼2 nm have been grown on unique two dimensional (2D) CdSe/CdS core@shell hexagonal nanoheteroplatelets of 20 nm diameter to form unprecedented 2D CdSe/CdS-Au HNCs and detailed optical characterization has been carried out to determine the dimensionality based electron transfer dynamics on the ultrafast scale. Steady state optical absorption studies show that upon growing Au NPs onto the 2D nanoplates, a new band appears in the red region of the spectra (500-800 nm), which suggests a strong interaction between the exciton of the core-shell and the plasmon of the metal NPs. Fluorescence studies showed the quenching of emission of the semiconductor domains upon the growth of the metallic domains. Detailed optical and TRPL studies suggested efficient charge transfer from the 2D CdSe/CdS to the Au domains, irrespective of excitation wavelength. Femtosecond transient absorption studies suggest that the electron transfer from the 2D hybrid nanocrystals to the metal domain is on an ultrafast time scale (∼800 fs). No evidence is observed for charge transfer from the 2 nm Au domains to the semiconductor seeds. The broad absorption in the visible region of the hybrid nanocrystals and the ultrafast charge transfer facilitates very efficient photo-catalytic reactions under direct sun light, as a case study. PMID:27533050

  13. Low temperature synthesis of RGO-Au nanocomposite with apparently reduced time and its application as a chemical sensor

    NASA Astrophysics Data System (ADS)

    Tuz Johra, Fatima; Jung, Woo-Gwang

    2016-01-01

    For the first time, a reduced graphene oxide (RGO)-Au nanocomposites (NC) is synthesized at a low temperature by refluxing without a surfactant. Transmission electron microscopy suggests that Au nanoparticles (NPs) 10-20 nm in size are dispersed on the RGO thin film. X-ray diffraction study, UV-vis spectrometry, and Raman spectroscopy confirmed the reduction of graphene oxide (GO). This RGO-Au NC shows an excellent ability to detect Cr(VI) by electrochemical sensing, with good responses to both current and voltage. A glassy carbon electrode modified with the NC shows a significant voltammetric reduction peak. The voltammetric detection ability is highly dependent on the pH of the electrolyte. The large surface area of RGO's porous structure and the electroactive Au NPs both allow free exchange of reaction intermediates, resulting in significantly enhanced Cr(VI) reduction activity. The RGO-Au electrode shows a good linear response in a range of Cr(VI) concentrations from 10 to 800 μM and a high sensitivity of 0.0146 μA μM-1 with a 2.10 μM detection limit.

  14. A novel glucose biosensor platform based on Ag@AuNPs modified graphene oxide nanocomposite and SERS application.

    PubMed

    Gupta, Vinod Kumar; Atar, Necip; Yola, Mehmet Lütfi; Eryılmaz, Merve; Torul, Hilal; Tamer, Uğur; Boyacı, Ismail Hakkı; Ustündağ, Zafer

    2013-09-15

    This study represents a novel template demonstration of a glucose biosensor based on mercaptophenyl boronic acid (MBA) terminated Ag@AuNPs/graphene oxide (Ag@AuNPs-GO) nanomaterials. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) method. The TEM image shows that Ag@AuNPs in the nanocomposite is in the range of diameters of 10-20 nm. The nanocomposite was used for the determination of glucose through the complexation between boronic acid and diol groups of glucose. Thus, a novel glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into MBA terminated Ag@AuNPs-GO nanocomposite film (MBA-Ag@AuNPs-GO). The linearity range of glucose was obtained as 2-6mM with detection limit of 0.33 mM. The developed biosensor was also applied successfully for the determination of glucose in blood samples. The concentration value of glucose in blood samples was calculated to be 1.97±0.002 mM from measurements repeated for six times. PMID:23816220

  15. Layered sphere-shaped TiO₂ capped with gold nanoparticles on structural defects and their catalysis of formaldehyde oxidation.

    PubMed

    Ma, Chunyan; Pang, Guanglong; He, Guangzhi; Li, Yang; He, Chi; Hao, Zhengping

    2016-01-01

    We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials, which were formed by layered deposition of multiple anatase TiO2 nanosheets. The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet, including crystal steps and edges, thereby fixing the Au-TiO2 perimeter interface. Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface. The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface. Such vacancies are essential for generating active oxygen species (*O(-)) on the TiO2 surface and Ti(3+) ions in bulk TiO2. These ions can then form Ti(3+)-O(-)-Ti(4+) species, which are known to enhance the catalytic activity of formaldehyde (HCHO) oxidation. These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials. PMID:26899647

  16. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  17. Low temperature activation of Au/Ti getter film for application to wafer-level vacuum packaging

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Moulin, Johan; Lani, Sébastien; Hallais, Géraldine; Renard, Charles; Bosseboeuf, Alain

    2015-03-01

    Non-evaporable getter (NEG) thin films based on alloys of transition metals have been studied by various authors for vacuum control in wafer-level packages of micro electro mechanical systems (MEMS). These materials have typically a relatively high activation temperature (300-450 °C) which is incompatible with some temperature sensitive MEMS devices. In this work we investigate the potential of Au/Ti system with a thin or ultrathin non oxidizable Au layer as a low activation temperature getter material. In this bilayer system, gettering activation is produced by thermal outdiffusion of titanium atoms through the gold film. The outdiffusion kinetics of titanium was modelled and characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS) at various temperatures. Results confirm that Au/Ti bilayer is a promising getter material for wafer-level packaging with an activation temperature below 300 °C for 1 h annealing time.

  18. Ayty: a New Line-List for Hot Formaldehyde

    NASA Astrophysics Data System (ADS)

    Al-Refaie, Ahmed Faris; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey

    2015-06-01

    The ExoMol [1] project aims at providing spectroscopic data for key molecules that can be used to characterize the atmospheres of exoplanets and cool stars. Formaldehyde (H2CO) is of growing importance in studying and modelling terrestrial atmospheric chemistry and dynamics. It also has relevance in astrophysical phenomena that include interstellar medium abundance, proto-planetary and cometary ice chemistry and masers from extra-galactic sources. However there gaps in currently available absolute intensities and a lack of higher rotational excitations that makes it unfeasible to accurately model high temperature systems such as hot Jupiters. Here we present AYTY [2], a new line list for formaldehyde applicable to temperatures up to 1500 K. AYTY contains almost 10 million states reaching rotational excitations up to J=70 and over 10 billion transitions at up to 10 000 cm-1. The line list was computed using the variational ro-vibrational solver TROVE with a refined ab-initio potential energy surface and dipole moment surface. J.~Tennyson and S.~N. Yurchenko MNRAS, 425:21--33, 2012. A.~F. Al-Refaie, S.~N. Yurchenko, A.~Yachmenev, and J.~Tennyson MNRAS, 2015.

  19. Formaldehyde assay by capacitance versus voltage and impedance measurements using bi-layer bio-recognition membrane.

    PubMed

    Ben Ali, M; Korpan, Y; Gonchar, M; El'skaya, A; Maaref, M A; Jaffrezic-Renault, N; Martelet, C

    2006-12-15

    A novel formaldehyde sensitive biosensor based on bacterial formaldehyde dehydrogenase (FDH) as a bio-recognition element has been developed. The bio-recognition membrane had bi-layer architecture and consisted of FDH, cross-linked with albumin, and of the cofactor NAD at a high concentration level (first layer). The second layer was a negatively charged Nafion membrane, which prevented a leakage of negatively charged NAD molecules from the bio-membrane. As transducers, gold electrodes SiO(2)/Si/SiO(2)/Ti/Au and electrolyte-insulator-semiconductor Si/SiO(2) (EIS) structures have been used. Changes in capacitance and impedance properties of the bio-recognition membrane have been used for monitoring formaldehyde concentration in a bulk solution. It has been shown that formaldehyde can be detected within a concentration range from 1 microM to 20mM depending on the type of transduction used, with a detection limit of 1 and 100 microM for gold-based and EIS-based transducers, respectively. PMID:16516460

  20. Formation of Formaldehyde and Glyoxal From The Toluene + Oh Reaction

    NASA Astrophysics Data System (ADS)

    Volkamer, R.; Wirtz, K.; Platt, U.

    Aromatic hydrocarbons are emitted into the urban atmosphere mostly as part of au- tomobile exhaust. Toluene thereby is the single most abundant aromatic compound emitted into the atmosphere. Despite the importance of aromatic hydrocarbon oxi- dation for the formation of photooxidants from urban plumes the oxidation mech- anism of aromatic hydrocarbons is far from being understood.Considerable progress has been made in recent years concerning our understanding of the ring-retaining path- ways, while major uncertainties remain to be linked with the operative ring-cleavage mechanisms. The representation of the aromatic oxidation in presently used chemical transport models (CTM) is estimated a major uncertainty for these models. This work presents data on formaldehyde (HCHO) and glyoxal, which are two impor- tant ring-cleavage products from the the toluene + OH reaction. While glyoxal was observed to form as a high yield primary product (Volkamer et al., JPC A, 2001, 105, 7865-7874) the formation of HCHO is observed delayed, i.e. as a secondary prod- uct. The temporal behaviour of glyoxal and HCHO concentrations allowed to con- clude that short lived stable intermediate compounds must form upon ring-cleavage of toluene. With an approximate lifetime of the order of ten minutes, these highly reac- tive intermediate compounds are likely to be a significant radical source. Atmospheric implications of the results are adressed.

  1. Comparison of some morphological and absorption properties of the nanoparticles Au/TiO2 embedded films prepared by different technologies on the substrates for application in the plasmonic solar cell

    NASA Astrophysics Data System (ADS)

    Dao, Khac An; Thuy Nguyen, Thi; Huong Nguyen, Thi Mai; Nguyen, Duy Thien

    2015-03-01

    The nanoparticle Au/TiO2 embedded system plays a very important role in the plasmonic solar cell. The features of the nanoparticle embedded system will determine light enhancement, light absorption, scattering and localized surface plasmon resonance (LSPR), aiming to enhance the efficiency of the plasmatic solar cell. The characterizations of nanoparticles Au/TiO2 embedded system consist of many parameters: the sizes of nanoparticles (Au, TiO2), the weight ratio of Au to TiO2, the thickness of the single layer or multilayer of Au/TiO2, the arrangements of Au and TiO2 nanoparticles in integrated-matrix system, the light absorption, scattering and LSPR capacities of the Au/TiO2 system. These parameters, however, depend on the technological conditions, the structure of plasmonic solar cell as well as the used substrate materials. This paper presents some technological developments for nanoparticles Au/TiO2 embedded systems by different methods, including the preparation of the mixer Au/TiO2 solutions and fabrication of the nanoparticle Au/TiO2 systems with different Au percentages on several substrates (glass/ITO and AAO(Al)/Si…), and measured results of the morphological, structural and optical properties using FESEM, EDX, UV-vis spectroscopy. The comparisons of experiment results between different technology conditions and substrates (glass/ITO, AAO(Al)/Si…) are also shown and discussed with the aim of choosing the suitable technological process and technological conditions for application in the plasmonic solar cell.

  2. Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions

    EPA Science Inventory

    An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex ch...

  3. Effect of Relative Humidity on Formaldehyde Decontamination

    PubMed Central

    Spiner, David R.; Hoffman, Robert K.

    1971-01-01

    Death rate studies were conducted to determine the effect of varying the concentration, humidity, and type of surface on the sporicidal activity of formaldehyde gas. Washed and unwashed spores were similarly exposed to detect the influence of residual nutrient growth medium upon the rate of kill. The results indicated that the sporicidal activity of formaldehyde gas varies directly with its concentration. Relative humidities (RH) over 50% proved essential for sterility. Spores on a porous surface (cotton cloth) were more readily killed at lower RH than those on a nonporous surface (glass). The reverse occurred at very high RH. At 75% RH, the unwashed spores on glass were killed faster than the washed spores. Images PMID:5002898

  4. Formaldehyde in envelopes of interstellar dark clouds

    NASA Technical Reports Server (NTRS)

    Federman, S. R.; Allen, M.

    1991-01-01

    Observed formaldehyde column densities of 1 x 10 to the 12th - 3 x 10 to the 13th/sq cm in cloud envelopes along lines of sight with A(V) = 1-4 mag can not be explained with the current understanding of interstellar gas phase chemistry. However, these column densities can be reproduced by a simple time-dependent model in which H2CO is supplied to the gas phase by the erosion of icy grain mantles. The release of H2CO from the grain mantles must occur on time scales comparable to the time scales for mixing from the cloud interior to the cloud envelope. Thus, in low-density regions of clouds, it appears that formaldehyde is the second molecule whose gas phase source is primarily ejection from grains. This simple model suggests understanding gas phase steady state in clouds on macroscopic, rather than microscopic, spatial scales.

  5. Formaldehyde-exposure characterization in garment-manufacturing plants: a composite summary of three in-depth industrial-hygiene surveys

    SciTech Connect

    Elliott, L.J.; Stayner, L.T.; Blade, L.M.; Halperin, W.; Keenlyside, R.

    1987-01-01

    The extent of exposure to formaldehyde was investigated at three garment manufacturing facilities using fabrics pretreated with a formaldehyde-based resin system. Two of the facilities (in Georgia) operated on a two-shift basis with approximately 1000 and 500 workers; one facility (in Pennsylvania) operated on a one-shift basis and had approximately 600 workers. The facilities cut and sewed men's dress shirts from treated fabric. Measured exposures to formaldehyde, respirable dust, and organic cleaning solvent vapors were all below the applicable American Conference of Governmental Industrial Hygienists Threshold Limit Values and Occupational Safety and Health Administration Permissible Exposure Limits.

  6. Preparation of Au-polydopamine functionalized carbon encapsulated Fe3O4 magnetic nanocomposites and their application for ultrasensitive detection of carcino-embryonic antigen

    PubMed Central

    Ji, Lei; Yan, Tao; Li, Yan; Gao, Jian; Wang, Qi; Hu, Lihua; Wu, Dan; Wei, Qin; Du, Bin

    2016-01-01

    A novel carbon encapsulated Fe3O4 nanoparticles embedded in two-dimensional (2D) porous graphitic carbon nanocomposites (Fe3O4@C@PGC nanocomposites) were synthesized by situ synthesis strategy, which provided a sensor platform owing to a large aspect ratio and porous structure. Polydopamine (PDA) were modified on the surface of Fe3O4@C@PGC nanocomposites through self-polymerization of dopamine, acting as both the reductant and template for one-step synthesis of gold nanoparticles. The prepared Au/PDA/Fe3O4@C@PGC nanocomposites show ferromagnetic features, extremely excellent electron transfer, large specific surface area and excellent dispersing property. These are conducive to the electrochemical signal output and the immobilization of antibody. In this work, a highly label-free sensitive magnetic immunosensor was developed based on Au/PDA/Fe3O4@C@PGC nanocomposites for the detection of carcino-embryonic antigen (CEA). The magnetic glassy carbon electrode was used to fix the Au/PDA/Fe3O4@C@PGC nanocomposites with the help of magnetic force. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.001 ng/mL–20.0 ng/mL), a low detection limit (0.33 pg/mL), good reproducibility, selectivity and acceptable stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers. PMID:26868035

  7. Problems associated with the use of urea-formaldehyde foam for residential insulation. Part II. The effects of temperature and humidity on free formaldehyde, extractable formaldehyde, formaldehyde emission, and physical characteristics of the foam

    SciTech Connect

    Schutte, W.C.; Cole, R.S.; Frank, C.W.; Long, K.R.

    1981-02-01

    Results of testing with two products of urea-formaldehyde based foams are described. Results of three products have previously been reported. Methods for detection and quantitative determination of formaldehyde, design of the experimental chambers, and the procedures are described. Samples of Product D were monitored for about 29 days and samples of Product E were monitored for 60 days in chambers and results are tabulated for formaldehyde emission. Additional tests performed on the two products are: extractable formaldehyde (high and low temperature conditions); free formaldehyde (high and low temperature conditions); comparison of free formaldehyde concentration; density (high and low temperature conditions); shrinkage (high and low temperature conditions). Control panels were constructed to simulate a wall in a home and observations were made and compared with results of the experimental products.

  8. Formaldehyde exposure affects growth and metabolism of common bean

    SciTech Connect

    Mutters, R.G.; Madore, M. ); Bytnerowicz, A. )

    1993-01-01

    Recent state and federal directives have slated a substantial increase in the use of methanol as an alternative to gasoline in both fleet and private vehicles in the coming decade. The incomplete combustion of methanol produces formaldehyde vapor, and catalytic converter technology that completely oxidizes formaldehyde has yet to be developed. The approach of this study was to use a range of methanol concentrations encompassing levels currently found or that may occur in the future in the ambient air of some heavily polluted areas to test the potential phytotoxicity of formaldehyde. The study had the following objectives: (1) design and build a formaldehyde vapor generator with sufficient capacity for long-term plant fumigations; (2) determine growth response of common bean to formaldehyde; (3) evaluate physiological and biochemical changes of bean plants associated with formaldehyde exposures. 20 refs., 2 figs., 2 tabs.

  9. Determination of Formaldehyde in Cigarette Smoke

    NASA Astrophysics Data System (ADS)

    Wong, Jon W.; Ngim, Kenley K.; Eiserich, Jason P.; Yeo, Helen C. H.; Shibamoto, Takayuki; Mabury, Scott A.

    1997-09-01

    Formaldehdye is considered a hazardous air pollutant with numerous sources that include environmental tobacco smoke (ETS). With the increasing interest regarding ETS and public health the measurement of formaldehyde readily lends itself to a laboratory experiment comparing methods of analysis. This experiment involves the collection, derivatization, extraction, and analysis of formaldehyde from cigarette smoke using two methods. Formaldehyde is extracted from smoke and derivitized with a solution of 2,4-DNPH with subsequent cleanup by solid-phase extraction and analysis of the hydrazone by HPLC with UV detection; additionally a solution of cysteamine yields the corresponding thiazolidine derivative that is liquid/liquid extracted and subsequently analyzed by either GC with NPD or FPD (sulfur mode). Reasonable agreement among the methods was obtained by lab demonstrators with spike recoveries yielding 94.7 + 6.8 (n=5) and 89.2 (n = 4) % for NPD and FPD, respectively while HPLC spiked recoveries were 83.6 + 3.2 (n = 5) %; mean class spike recoveries ranged from 80-100%. Student results (in mg/cigarette) from smoke samples were similar to literature values with 163.2 + 69.2 (n = 7) and 149.4 (n = 7) % for NPD and FPD, respectively; the HPLC result was significantly lower at 45.1 + 23.7(n = 7) with losses presumably due to hydrazone precipitating from the smoke extracted solution. Students particularly benefited from the "real world" nature of the analysis and the experience evaluating disparate methods of determining a common analyte.

  10. Health and environmental effects profile for formaldehyde

    SciTech Connect

    Not Available

    1985-10-01

    The Health and Environmental Effects Profile for formaldehyde was prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency Response to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human health, aquatic life, and environmental effects of hazardous-waste constituents. Quantitative estimates are presented, provided sufficient data are available. Existing data are insufficient to determine an Acceptable Daily Intake (ADI) or a carcinogenic potency factor for formaldehyde. The Reportable Quantity (RQ) value of 1, 10, 100, 1000, or 5000 pounds is used to determine the quantity of a hazardous substance for which notification is required in the event of a release as specified by CERCLA based on chronic toxicity. The RQ value for formaldehyde is 10.

  11. Importance of formaldehyde in cloud chemistry

    NASA Technical Reports Server (NTRS)

    Adewuyi, Y. G.; Cho, S.-Y.; Tsay, R.-P.; Carmichael, G. R.

    1984-01-01

    A physical-chemical model which is an extension of that of Hong and Carmichael (1983) is used to investigate the role of formaldehyde in cloud chemistry. This model takes into account the mass transfer of SO2, O3, NH3, HNO3, H2O2, CO2, HCl, HCHO, O2, OH and HO2 into cloud droplets and their subsequent chemical reactions. The model is used to assess the importance of S(IV)-HCHO adduct formation, the reduction of H2O2 by HCHO, HCHO-free radical interactions, and the formation of HCOOH in the presence of HCHO in cloud droplets. Illustrative calculations indicate that the presence of HCHO inhibits sulfate production rate in cloud droplets. The direct inhibition of sulfate production rate in cloudwater due to nucleophilic addition of HSO3(-) to HCHO(aq) to form hydroxymethanesulfonate is generally low for concentrations of HCHO typical of ambient air. However, inhibition of sulfate production due to formaldehyde-free radical interactions in solution can be important. These formaldehyde-free radical reactions can also generate appreciable quantities of formic acid.

  12. Tailored synthesis of photoactive TiO ₂ nanofibers and Au/TiO ₂ nanofiber composites: structure and reactivity optimization for water treatment applications.

    PubMed

    Nalbandian, Michael J; Greenstein, Katherine E; Shuai, Danmeng; Zhang, Miluo; Choa, Yong-Ho; Parkin, Gene F; Myung, Nosang V; Cwiertny, David M

    2015-02-01

    Titanium dioxide (TiO2) nanofibers with tailored structure and composition were synthesized by electrospinning to optimize photocatalytic treatment efficiency. Nanofibers of controlled diameter (30-210 nm), crystal structure (anatase, rutile, mixed phases), and grain size (20-50 nm) were developed along with composite nanofibers with either surface-deposited or bulk-integrated Au nanoparticle cocatalysts. Their reactivity was then examined in batch suspensions toward model (phenol) and emerging (pharmaceuticals, personal care products) pollutants across various water qualities. Optimized TiO2 nanofibers meet or exceed the performance of traditional nanoparticulate photocatalysts (e.g., Aeroxide P25) with the greatest reactivity enhancements arising from (i) decreasing diameter (i.e., increasing surface area), (ii) mixed phase composition [74/26 (±0.5) % anatase/rutile], and (iii) small amounts (1.5 wt %) of surface-deposited, more so than bulk-integrated, Au nanoparticles. Surface Au deposition consistently enhanced photoactivity by 5- to 10-fold across our micropollutant suite independent of their solution concentration, behavior that we attribute to higher photocatalytic efficiency from improved charge separation. However, the practical value of Au/TiO2 nanofibers was limited by their greater degree of inhibition by solution-phase radical scavengers and higher rate of reactivity loss from surface fouling in nonidealized matrixes (e.g., partially treated surface water). Ultimately, unmodified TiO2 nanofibers appear most promising for use as reactive filtration materials because their performance was less influenced by water quality, although future efforts must increase the strength of TiO2 nanofiber mats to realize such applications. PMID:25582552

  13. Validation of an HPLC method on short columns to assay ketoconazole and formaldehyde in shampoo.

    PubMed

    Nguyen, Minh Nguyet A; Tallieu, L; Plaizier-Vercammen, J; Massart, D L; Vander Heyden, Y

    2003-04-24

    An HPLC method to determine simultaneously ketoconazole and formaldehyde in an anti-dandruff shampoo, originally developed on a long column, was transferred to two short columns with similar stationary phase properties, but with a length of at the most 30% of the initial one. Using the conventional column as reference, the fast HPLC methods on the short columns were validated. The validation characteristics consisted of selectivity, linearity range, precision (repeatability and time-different intermediate precision), bias and robustness. For the ketoconazole assay, linearity for peak area was found in the concentration range up to 0.20 mg/ml. For formaldehyde, two calibration ranges (0-10 x 10(-5) and 0-10 x 10(-4)%) were linear, both for peak area and height. The assays for both ketoconazole and formaldehyde in these ranges showed no bias and an acceptable precision, although the precision found with the short columns was slightly worse than with the long one. The robustness tests were performed applying a Plackett-Burman design. For the ketoconazole assay, 6 factors were examined in a 12 experiments design and for formaldehyde, 11 factors in 16 experiments. The methods were found to be robust. Despite the somewhat less good precision the transfer seems to be successful and the obtained assays on the short columns are applicable for fast routine analysis. PMID:12852444

  14. Determination of formaldehyde in food and feed by an in-house validated HPLC method.

    PubMed

    Wahed, P; Razzaq, Md A; Dharmapuri, S; Corrales, M

    2016-07-01

    Formalin is carcinogenic and is detrimental to public health. The illegal addition of formalin (37% formaldehyde and 14% methanol) to foods to extend their shelf-life is considered to be a common practice in Bangladesh. The lack of accurate methods and the ubiquitous presence of formaldehyde in foods make the detection of illegally added formalin challenging. With the aim of helping regulatory authorities, a sensitive high performance liquid chromatography method was validated for the quantitative determination of formaldehyde in mango, fish and milk. The method was fit-for-purpose and showed good analytical performance in terms of specificity, linearity, precision, recovery and robustness. The expanded uncertainty was <35%. The validated method was applied to screen samples of fruits, vegetables, fresh fish, milk and fish feed collected from different local markets in Dhaka, Bangladesh. Levels of formaldehyde in food samples were compared with published data. The applicability of the method in different food matrices might mean it has potential as a reference standard method. PMID:26920321

  15. 40 CFR 721.9480 - Resorcinol, formaldehyde substituted carbomonocycle resin (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Resorcinol, formaldehyde substituted... New Uses for Specific Chemical Substances § 721.9480 Resorcinol, formaldehyde substituted... chemical substance identified generically as resorcinol, formaldehyde substituted carbomonocycle resin...

  16. 40 CFR 721.9480 - Resorcinol, formaldehyde substituted carbomonocycle resin (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Resorcinol, formaldehyde substituted... New Uses for Specific Chemical Substances § 721.9480 Resorcinol, formaldehyde substituted... chemical substance identified generically as resorcinol, formaldehyde substituted carbomonocycle resin...

  17. 40 CFR 721.9480 - Resorcinol, formaldehyde substituted carbomonocycle resin (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Resorcinol, formaldehyde substituted... New Uses for Specific Chemical Substances § 721.9480 Resorcinol, formaldehyde substituted... chemical substance identified generically as resorcinol, formaldehyde substituted carbomonocycle resin...

  18. 40 CFR 721.9480 - Resorcinol, formaldehyde substituted carbomonocycle resin (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Resorcinol, formaldehyde substituted... New Uses for Specific Chemical Substances § 721.9480 Resorcinol, formaldehyde substituted... chemical substance identified generically as resorcinol, formaldehyde substituted carbomonocycle resin...

  19. Formaldehyde and LeukemiA: Epidemiology, Potential Mechanisms and Implications for Risk Assessment

    EPA Science Inventory

    Formaldehyde is widely used in the United States and other countries. Occupational and environmental exposures to formaldehyde may be associated with an increased risk of leukemia in exposed individuals. However, risk assessment of formaldehyde and leukemia has been challenging ...

  20. Exposure to formaldehyde and its potential human health hazards.

    PubMed

    Kim, Ki-Hyun; Jahan, Shamin Ara; Lee, Jong-Tae

    2011-10-01

    A widely used chemical, formaldehyde is normally present in both indoor and outdoor air. The rapid growth of formaldehyde-related industries in the past two decades reflects the result of its increased use in building materials and other commercial sectors. Consequently, formaldehyde is encountered almost every day from large segments of society due to its various sources. Many governments and agencies around the world have thus issued a series of standards to regulate its exposure in homes, office buildings, workshops, public places, and food. In light of the deleterious properties of formaldehyde, this article provides an overview of its market, regulation standards, and human health effects. PMID:22107164

  1. Formaldehyde crosslinking: a tool for the study of chromatin complexes.

    PubMed

    Hoffman, Elizabeth A; Frey, Brian L; Smith, Lloyd M; Auble, David T

    2015-10-30

    Formaldehyde has been used for decades to probe macromolecular structure and function and to trap complexes, cells, and tissues for further analysis. Formaldehyde crosslinking is routinely employed for detection and quantification of protein-DNA interactions, interactions between chromatin proteins, and interactions between distal segments of the chromatin fiber. Despite widespread use and a rich biochemical literature, important aspects of formaldehyde behavior in cells have not been well described. Here, we highlight features of formaldehyde chemistry relevant to its use in analyses of chromatin complexes, focusing on how its properties may influence studies of chromatin structure and function. PMID:26354429

  2. A simple approach to the synthesis of eccentric Au@SiO2 Janus nanostructures and their catalytic applications

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Yang, Di; Hu, Huicheng; Chen, Lei; Xu, Yong; Qu, Lili; Yang, Peipei; Zhang, Qiao

    2016-06-01

    In this paper, we present a simple method to synthesize eccentric Au@SiO2 Janus nanoparticles. By simply tuning the concentration of poly(vinyl pyrrolidone) (PVP), the surface of gold nanoparticle can be partially or fully wrapped with the amphiphilic ligand. As a result, Janus nanoparticle or concentric core-shell nanostructures can be obtained, respectively. A systematic study has been carried out to confirm the function of PVP molecules. The as-prepared Janus nanoparticle can act as a catalyst to catalyze the reduction of 4-nitrophenol, while the core-shell nanostructure is not active due to the coverage of dense silica shell. This work provides a robust and scalable method to produce Au@SiO2 Janus nanoparticles.

  3. Adsorption between TC-stabilized AuNPs and the phosphate group: application of the PTP1B activity assay.

    PubMed

    Lv, Jun; Wang, Xiaonan; Zhang, Yuanyuan; Li, Defeng; Zhang, Juan; Sun, Lizhou

    2015-12-01

    Based on the adsorption between tetracycline (TC) and phosphate groups, a general colorimetric method is explored in this work by using TC-stabilized gold nanoparticles (TC/AuNPs) and 4-aminophenyl phosphate-functionalized Fe3O4 magnetic nanoparticles (APP/MNPs). Taking protein tyrosine phosphatase 1B (PTP1B) as an example, 4-aminophenyl phosphate (APP) can be hydrolyzed into 4-aminophenol (AP) by PTP1B, resulting in the disappearance of the phosphate group on the outer layer of MNPs and the loss of corresponding adsorptive ability. Upon addition of TC/AuNP solution, TC/AuNPs will remain in the supernatant solution after magnetic separation and a high absorbance value can be observed. So PTP1B activity is related to the concentrations of TC/AuNPs in the supernatant solution. In this work, the enzyme activity can be determined at levels as low as 0.0885 U mL(-1) and over a linear detection range as wide as 0.1 U mL(-1) to 0.9 U mL(-1). Moreover, using the proposed method, the inhibition effect of betulinic acid (BA) and sodium orthovanadate (Na3VO4) on PTP1B activity can be tested with IC50 values of 30 μM and 4 μM, respectively. Therefore, a universal platform for the accurate colorimetric analysis of kinase and phosphatase activities can be established through the adsorption between TC and phosphate groups. PMID:26523458

  4. Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor.

    PubMed

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2016-01-01

    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor. PMID:26799703

  5. Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2016-01-01

    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current–voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung’s method and Norde’s technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I–V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor. PMID:26799703

  6. Embryo toxicity and teratogenicity of formaldehyde.

    PubMed

    Thrasher, J D; Kilburn, K H

    2001-01-01

    C-14 formaldehyde crosses the placenta and enters fetal tissues. The incorporated radioactivity is higher in fetal organs (i.e., brain and liver) than in maternal tissues. The incorporation mechanism has not been studied fully, but formaldehyde enters the single-carbon cycle and is incorporated as a methyl group into nucleic acids and proteins. Also, formaldehyde reacts chemically with organic compounds (e.g., deoxyribonucleic acid, nucleosides, nucleotides, proteins, amino acids) by addition and condensation reactions, thus forming adducts and deoxyribonucleic acid-protein crosslinks. The following questions must be addressed: What adducts (e.g., N-methyl amino acids) are formed in the blood following formaldehyde inhalation? What role do N-methyl-amino adducts play in alkylation of nuclear and mitochondrial deoxyribonucleic acid, as well as mitochondrial peroxidation? The fact that the free formaldehyde pool in blood is not affected following exposure to the chemical does not mean that formaldehyde is not involved in altering cell and deoxyribonucleic acid characteristics beyond the nasal cavity. The teratogenic effect of formaldehyde in the English literature has been sought, beginning on the 6th day of pregnancy (i.e., rodents) (Saillenfait AM, et al. Food Chem Toxicol 1989, pp 545-48; Martin WJ. Reprod Toxicol 1990, pp 237-39; Ulsamer AG, et al. Hazard Assessment of Chemicals; Academic Press, 1984, pp 337-400; and U.S. Department of Health and Human Services. Toxicological Profile of Formaldehyde; ATSDR, 1999 [references 1-4, respectively, herein]). The exposure regimen is critical and may account for the differences in outcomes. Pregnant rats were exposed (a) prior to mating, (b) during mating, (c) or during the entire gestation period. These regimens (a) increased embryo mortality; (b) increased fetal anomalies (i.e., cryptochordism and aberrant ossification centers); (c) decreased concentrations of ascorbic acid; and (d) caused abnormalities in enzymes of

  7. Comparison of the effects of formaldehyde and gaseous ozone on HBV-contaminated hospital quilts

    PubMed Central

    Guo, Dan; Li, Ziqiong; Jia, Bei; Che, Xiaoqiong; Song, Tianshuang; Huang, Wenxiang

    2015-01-01

    Background: Besides being highly infectious, Hepatitis B virus (HBV) is a major cause of liver disease worldwide. In hospital settings, it is easy for the environment and quilts to be contaminated by HBV patient blood and body fluids. Therefore, HBV can be transmitted to other patients via contaminated environmental surfaces or quilts, resulting in an HBV nosocomial infection. Formaldehyde and ozone are commonly used disinfectants that may influence this infectious situation. Objective: To investigate the clinical effectiveness of formaldehyde and gaseous ozone for the terminal cleaning of hospital quilts contaminated by HBV. Methods: Thin cloth and thick cotton soaked with the serum from high HBV copy number patients were prepared and disinfected using formaldehyde fumigation and gaseous ozone at different times. The copy numbers of HBV DNA in the HBV-contaminated cloth and cotton samples were measured quantitatively with fluorescent quantitative polymerase chain reaction (PCR). Results: When gaseous ozone was used to disinfect HBV-contaminated quilts for 23 minutes (min), 36 min, 49 min, and 90 min, the HBV DNA copy number displayed no significant decrease compared with the copy number before disinfection (P > 0.05). In comparison, the copy number of the HBV DNA in the cloth group decreased significantly (P < 0.05) after formaldehyde fumigation disinfection for 1 hour (h), and there was no difference when longer times and increased concentrations were used. In the thick cotton group, there was also a significant decrease (P < 0.05) of the HBV DNA copy numbers, but the decrease was not as dramatic. In addition, in this group, the disinfection effect observed at 4 h was the strongest. Conclusions: The application of ozone to disinfect HBV-contaminated hospital quilts possibly has no effect, whereas, formaldehyde oxide fumigation effectively reduced HBV copy numbers. PMID:26770591

  8. BLM protein mitigates formaldehyde-induced genomic instability

    PubMed Central

    Kumari, Anuradha; Owen, Nichole; Juarez, Eleonora; McCullough, Amanda K.

    2015-01-01

    Formaldehyde is a reactive aldehyde that has been classified as a class I human carcinogen by the International Agency for Cancer Research. There are growing concerns over the possible adverse health effects related to the occupational and environmental human exposures to formaldehyde. Although formaldehyde-induced DNA and protein adducts have been identified, the genomic instability mechanisms and the cellular tolerance pathways associated with formaldehyde exposure are not fully characterized. This study specifically examines the role of a genome stability protein, Bloom (BLM) in limiting formaldehyde-induced cellular and genetic abnormalities. Here, we show that in the absence of BLM protein, formaldehyde-treated cells exhibited increased cellular sensitivity, an immediate cell cycle arrest, and an accumulation of chromosome radial structures. In addition, live-cell imaging experiments demonstrated that formaldehyde-treated cells are dependent on BLM for timely segregation of daughter cells. Both wild-type and BLM-deficient formaldehyde-treated cells showed an accumulation of 53BP1 and γH2AX foci indicative of DNA double-strand breaks (DSBs); however, relative to wild-type cells, the BLM-deficient cells exhibited delayed repair. In response to formaldehyde exposure, we observed co-localization of 53BP1 and BLM foci at the DSB repair site, where ATM-dependent accumulation of formaldehyde-induced BLM foci occurred after the recruitment of 53BP1. Together, these findings highlight the significance of functional interactions among ATM, 53BP1, and BLM proteins as responders associated with the repair and tolerance mechanisms induced by formaldehyde. PMID:25770783

  9. Respiratory response to formaldehyde and off-gas of urea formaldehyde foam insulation.

    PubMed Central

    Day, J H; Lees, R E; Clark, R H; Pattee, P L

    1984-01-01

    In 18 subjects, 9 of whom had previously complained of various nonrespiratory adverse effects from the urea formaldehyde foam insulation (UFFI) in their homes, pulmonary function was assessed before and after exposure in a laboratory. On separate occasions formaldehyde, 1 part per million (ppm), and UFFI off-gas yielding a formaldehyde concentration of 1.2 ppm, were delivered to each subject in an environmental chamber for 90 minutes and a fume hood for 30 minutes respectively. None of the measures of pulmonary function used (forced vital capacity, forced expiratory volume in 1 second or maximal midexpiratory flow rate) showed any clinically or statistically significant response to the exposure either immediately after or 8 hours after its beginning. There were no statistically significant differences between the responses of the group that had previously complained of adverse effects and of the group that had not. There was no evidence that either formaldehyde or UFFI off-gas operates as a lower airway allergen or important bronchospastic irritant in this heterogeneous population. Images Fig. 1 PMID:6388780

  10. Influence of Precision of Emission Characteristic Parameters on Model Prediction Error of VOCs/Formaldehyde from Dry Building Material

    PubMed Central

    Wei, Wenjuan; Xiong, Jianyin; Zhang, Yinping

    2013-01-01

    Mass transfer models are useful in predicting the emissions of volatile organic compounds (VOCs) and formaldehyde from building materials in indoor environments. They are also useful for human exposure evaluation and in sustainable building design. The measurement errors in the emission characteristic parameters in these mass transfer models, i.e., the initial emittable concentration (C0), the diffusion coefficient (D), and the partition coefficient (K), can result in errors in predicting indoor VOC and formaldehyde concentrations. These errors have not yet been quantitatively well analyzed in the literature. This paper addresses this by using modelling to assess these errors for some typical building conditions. The error in C0, as measured in environmental chambers and applied to a reference living room in Beijing, has the largest influence on the model prediction error in indoor VOC and formaldehyde concentration, while the error in K has the least effect. A correlation between the errors in D, K, and C0 and the error in the indoor VOC and formaldehyde concentration prediction is then derived for engineering applications. In addition, the influence of temperature on the model prediction of emissions is investigated. It shows the impact of temperature fluctuations on the prediction errors in indoor VOC and formaldehyde concentrations to be less than 7% at 23±0.5°C and less than 30% at 23±2°C. PMID:24312497

  11. Pt@AuNPs integrated quantitative capillary-based biosensors for point-of-care testing application.

    PubMed

    Wu, Ze; Fu, Qiangqiang; Yu, Shiting; Sheng, Liangrong; Xu, Meng; Yao, Cuize; Xiao, Wei; Li, Xiuqing; Tang, Yong

    2016-11-15

    Current diagnostic technologies primarily rely on bulky and costly analytical instruments. Therefore, cost-effective and portable diagnosis tools that can be used for point-of-care tests (POCT) are highly desirable. In this study, we report a cost-effective, portable capillary-based biosensor for quantitative detection of biomarkers by the naked eye. This capillary-based biosensor was tested by measuring the distance of blue ink movement, which was directly correlated with the oxygen (O2) produced by efficient core-shell Pt@Au nanoparticles (Pt@AuNPs) catalysts decomposed hydrogen peroxide (H2O2). By linking the Pt@AuNPs with antibodies, capillary-based biosensor sandwich immunoassays were constructed. The concentrations of the target proteins were positively correlated with the distances of ink movement. To demonstrate their performance, the biosensors were used to detect the cancer biomarker sprostate-specific antigen (PSA) and carcinoembryonic antigen (CEA). The linear detection range (LDR) of the capillary-based biosensor for detecting PSA was from 0.02 to 2.5ng/mL, and the limit of detection (LOD) was 0.017ng/mL. LDR of the biosensor for detecting CEA was from 0.063 to 16ng/mL, and the LOD was 0.044ng/mL. For detection of PSA and CEA in clinical serum samples, the detection results of the capillary-based biosensor were well correlate with the results from of chemiluminescence immunoassays (CLIAs). Thus, the capillary-based biosensor may potentially be a useful strategy for point-of-care testing, in addition to being portable and cost effective. PMID:27240013

  12. Low temperature steam and formaldehyde sterilization.

    PubMed

    Robertshaw, R G

    1983-09-01

    A standard low temperature steam/formaldehyde autoclave was tested according to the manufacturer's instructions, using a range of test pieces containing Bacillus stearothermophilus spores as the challenge organism. There were failures in killing the challenge organism and the reasons for these are discussed. A description of modifications made to the autoclave is given together with details of an improved operating cycle. The performance of the modified autoclave was greatly improved and conditions were established for reliable and consistent sterilization of all the test pieces. A commercially produced prototype autoclave similarly modified also showed effective sterilization. PMID:6195245

  13. Low density, resorcinol-formaldehyde aerogels

    DOEpatents

    Pekala, R.W.

    1989-10-10

    The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density [<=]100 mg/cc; cell size [<=]0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 [angstrom]. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

  14. Low density, resorcinol-formaldehyde aerogels

    DOEpatents

    Pekala, Richard W.

    1991-01-01

    The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

  15. Low density, resorcinol-formaldehyde aerogels

    DOEpatents

    Pekala, R.W.

    1988-05-26

    The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.

  16. Low density, resorcinol-formaldehyde aerogels

    DOEpatents

    Pekala, Richard W.

    1989-01-01

    The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density .ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 .ANG.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

  17. Effect of Formaldehyde on Asthmatic Response to Inhaled Allergen Challenge

    PubMed Central

    Ezratty, Véronique; Bonay, Marcel; Neukirch, Catherine; Orset-Guillossou, Gaëlle; Dehoux, Monique; Koscielny, Serge; Cabanes, Pierre-André; Lambrozo, Jacques; Aubier, Michel

    2007-01-01

    Background Exposure to formaldehyde may lead to exacerbation of asthma. Objectives Our aim in this study was to investigate whether exposure to a low level (500 μg/m3) of formaldehyde enhances inhaled allergen responses. Methods Twelve subjects with intermittent asthma and allergy to pollen were exposed, at rest, in a double-blind crossover study to either formaldehyde or purified air for 60 min. The order of exposure to formaldehyde and air-only was randomized, and exposures were separated by 2 weeks. We also performed an allergen inhalation challenge after each exposure. Airway responsiveness to methacholine and lower airway inflammation (induced sputum) were assessed 8 hr after allergen challenge. Results The median dose of allergen producing a 15% decrease in forced expiratory volume in 1 sec (PD15FEV1) was 0.80 IR (index of reactivity) after formaldehyde exposure compared with 0.25 IR after air-only exposure (p = 0.06). Formaldehyde exposure did not affect allergen-induced increase in responsiveness to methacholine (p = 0.42). We found no formaldehyde-associated effect on the airway inflammatory response, in particular the eosinophilic inflammatory response, induced by the allergen challenge 8 hr before. Conclusion In this study, exposure to 500 μg/m3 formaldehyde had no significant deleterious effect on airway allergen responsiveness of patients with intermittent asthma; we found a trend toward a protective effect. PMID:17384766

  18. Gold nanowired: a linear (Au25)(n) polymer from Au25 molecular clusters.

    PubMed

    De Nardi, Marco; Antonello, Sabrina; Jiang, De-en; Pan, Fangfang; Rissanen, Kari; Ruzzi, Marco; Venzo, Alfonso; Zoleo, Alfonso; Maran, Flavio

    2014-08-26

    Au25(SR)18 has provided fundamental insights into the properties of clusters protected by monolayers of thiolated ligands (SR). Because of its ultrasmall core, 1 nm, Au25(SR)18 displays molecular behavior. We prepared a Au25 cluster capped by n-butanethiolates (SBu), obtained its structure by single-crystal X-ray crystallography, and studied its properties both experimentally and theoretically. Whereas in solution Au25(SBu)18(0) is a paramagnetic molecule, in the crystal it becomes a linear polymer of Au25 clusters connected via single Au-Au bonds and stabilized by proper orientation of clusters and interdigitation of ligands. At low temperature, [Au25(SBu)18(0)]n has a nonmagnetic ground state and can be described as a one-dimensional antiferromagnetic system. These findings provide a breakthrough into the properties and possible solid-state applications of molecular gold nanowires. PMID:25088331

  19. Measurement of formaldehyde H{sub 2}CO concentration in air using diode vertical-cavity lasers

    SciTech Connect

    Zaslavskii, V Ya; Nadezhdinskii, Aleksandr I; Ponurovskii, Ya Ya; Chernin, S M

    2011-01-31

    A two-channel gas-analysing spectrometer is developed using a vertical-cavity surface-emitting laser (VCSEL) ({lambda}=1.79 {mu}m) and a multi-pass cell (total optical length 39 m) for studying the absorption spectra and measuring the background concentration of formaldehyde. High-resolution absorption spectra of formaldehyde are obtained within the VCSEL frequency tuning range ({lambda} {approx}1.79 {mu}m). Changing the background concentration of H{sub 2}CO, the sensitivity limit of the gas analyser is estimated. (laser applications)

  20. Chromogenic Detection of Aqueous Formaldehyde Using Functionalized Silica Nanoparticles.

    PubMed

    El Sayed, Sameh; Pascual, Lluı́s; Licchelli, Maurizio; Martínez-Máñez, Ramón; Gil, Salvador; Costero, Ana M; Sancenón, Félix

    2016-06-15

    Silica nanoparticles functionalized with thiol reactive units and bulky polar polyamines were used for the selective colorimetric detection of formaldehyde. The reaction of thiols groups in the nanoparticles surface with a squaraine dye resulted in loss of the π-conjugation of the chromophores, and the subsequent bleaching of the solution. However, when formaldehyde was present in the suspension, the thiol-squaraine reaction was inhibited and a chromogenic response was observed. A selective response to formaldehyde was observed only when the thiol and polyamine groups were anchored to the silica surface. The observed selective response was ascribed to the fact that bulky polyamines generate a highly polar environment around thiols, which were only able to react with the small and polar formaldehyde, but not with other aldehydes. The sensing nanoparticles showed a limit of detection (LOD) for formaldehyde of 36 ppb in water. PMID:27250594

  1. Determination of tritiated formaldehyde in effluents from tritium facilities

    SciTech Connect

    Belot, Y.; Camus, H.; Marini, T. )

    1992-03-01

    Recent observations suggested that formal-dehyde can be incorporated in vegetation at a very high rate. In this paper, the authors develop a methodology for determining tritiated formaldehyde (CHTO) in gaseous effluent containing HTO and HT as dominant species. CHTO being very soluble in water is collected in a solution of carrier formaldehyde. This carrier is necessary for precipitating for formaldehyde derivative of dimedone and collecting it by filtration. The precipitate, which contains the formaldehyde hydrogens, is freed from exchangeable tritium, dried in oven, and combusted to water for tritium determination. CHTO can thus be separated from HTO with a high efficiency, leading to the possibility of determining accurately 1 Bq of CHTO in as much as 5 {times} 10{sup 4} Bq of HTO. The methodology has been applied in preliminary experiments to determine the ratio of CHTO to HTO in effluent from a tritium-handling facility and effluent released from solid miscellaneous wastes.

  2. Imaging Surface Reactions of Formaldehyde on TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenrong; Tang, Miru; Wang, Zhi-Tao; Ke, Zhu; Xia, Yaobiao; Park, Kenneth; Lyubinetsky, Igor; Dohnálek, Zdenek; Ge, Qingfeng

    2015-03-01

    Formaldehyde is involved in many surface catalytic and photo-catalytic reactions on metal oxides. We studied surface reactions of formaldehyde on reduced TiO2(110) surfaces using variable-temperature scanning tunneling microscopy (STM) and density functional theory (DFT). STM images taken from a same area at various temperatures clearly show that formaldehyde preferentially adsorbs on the bridge-bonded oxygen vacancy (VO) defect sites. Bias-dependent STM images suggest the bonding configurations of the Ti-bound CH2O and the VO-bound CH2O. The isothermal time dependent images show the rotation of VO-bound CH2O and the two diffusion channels of formaldehyde at different temperatures. We also directly observed the formation of formaldehyde dimmer.

  3. Application of Au-Sn eutectic bonding in hermetic radio-frequency microelectromechanical system wafer level packaging

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Choa, Sung-Hoon; Kim, Woonbae; Hwang, Junsik; Ham, Sukjin; Moon, Changyoul

    2006-03-01

    Development of packaging is one of the critical issues toward realizing commercialization of radio-frequency-microelectromechanical system (RF-MEMS) devices. The RF-MEMS package should be designed to have small size, hermetic protection, good RF performance, and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low-temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at temperatures below 300°C is used. Au-Sn multilayer metallization with a square loop of 70 µm in width is performed. The electrical feed-through is achieved by the vertical through-hole via filling with electroplated Cu. The size of the MEMS package is 1 mm × 1 mm × 700 µm. The shear strength and hermeticity of the package satisfies the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

  4. Fixed-frequency and Frequency-agile (au, HTS) Microstrip Bandstop Filters for L-band Applications

    NASA Technical Reports Server (NTRS)

    Saenz, Eileen M.; Subramanyam, Guru; VanKeuls, Fred W.; Chen, Chonglin; Miranda, Felix A.

    2001-01-01

    In this work, we report on the performance of a highly selective, compact 1.83 x 2.08 cm(exp 2) (approx. 0.72 x 0.82 in(exp 2) microstrip line bandstop filter of YBa2CU3O(7-delta) (YBCO) on LaAlO3 (LAO) substrate. The filter is designed for a center frequency of 1.623 GHz for a bandwidth at 3 dB from reference baseline of less than 5.15 MHz, and a bandstop rejection of 30 dB or better. The design and optimization of the filter was performed using Zeland's IE3D circuit simulator. The optimized design was used to fabricate gold (Au) and High-Temperature Superconductor (HTS) versions of the filter. We have also studied an electronically tunable version of the same filter. Tunability of the bandstop characteristics is achieved by the integration of a thin film conductor (Au or HTS) and the nonlinear dielectric ferroelectric SrTiO3 in a conductor/ferroelectric/dielectric modified microstrip configuration. The performance of these filters and comparison with the simulated data will be presented.

  5. Partially-irreversible sorption of formaldehyde in five polymers

    NASA Astrophysics Data System (ADS)

    Ye, Wei; Cox, Steven S.; Zhao, Xiaomin; Frazier, Charles E.; Little, John C.

    2014-12-01

    Due to its environmental ubiquity and concern over its potential toxicity, the mass-transfer characteristics of formaldehyde are of critical importance to indoor air quality research. Previous studies have suggested that formaldehyde mass transfer in polymer is partially irreversible. In this study, mechanisms that could cause the observed irreversibility were investigated. Polycarbonate and four other polymeric matrices were selected and subjected to formaldehyde sorption/desorption cycles. Mass transfer of formaldehyde was partially irreversible in all cases, and three potential mechanisms were evaluated. First, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis was used to investigate possible formaldehyde polymerization on polymer surfaces. ATR-FTIR showed no detectable paraformaldehyde or formaldehyde on the film surfaces that had been exposed to formaldehyde and air. ATR-FTIR did detect aliphatic acids suggesting oxidation had occurred on film surfaces as a result of exposure to formaldehyde. However, additional study suggested that air is not the primary cause for irreversibility. Second, statistical physics theory was tested as a possible explanation. According to this theory, reversible and irreversible sorption could be taking place simultaneously. The irreversible fraction should be constant during sorption and the fraction could be determined by performing a complete sorption/desorption test. The sorption/desorption data was consistent with this theory. Third, chemisorption was considered as another possible cause for irreversibility. Extraction/fluorimetry testing of post-sorption and post-desorption polymer films showed measurable quantities of formaldehyde suggesting that some of the chemisorbed formaldehyde was reversible at the higher extraction temperature. Further quantitative study on chemical reaction products is needed.

  6. Formaldehyde exposure and acute health effects study

    SciTech Connect

    Quackenboss, J.J.; Lebowitz, M.D.; Michaud, J.P.; Bronnimann, D. )

    1989-01-01

    To assess the effects of formaldehyde exposures on health, exposure groups were defined using baseline exposure and health questionnaires. Formaldehyde concentrations were poorly correlated with these exposure classifications, perhaps due to the time delay between classification and monitoring. The 151 households reported here had a mean HCHO concentration of 35 (S.E. 1.5 and median 30) {mu}g/m{sup 3}. Passive samplers prepared in our lab were calibrated in a chamber to derive an estimated sampling rate of 0.311 {mu}g/(mg {center dot} m{sup {minus}3} {center dot} hr). They were also compared to commercially available samplers inside of the homes, with a correlation coefficient of 0.896 and mean difference of 2.6 {mu}g/m{sup 3}. In this report of initial findings from an ongoing study, daily symptoms and peak expiratory flow measurements were compared with an HCHO exposure classification based on the median measured concentrations. None of the symptoms groups were related to HCHO exposure when controlling for age and sex. There was a significant relationship between HCHO exposure and variability in peak expiratory flows that was dependent on age group. It may be especially important to assess the variability in reactive individuals and children to determine the short-term effects of HCHO exposures and possible long-term consequences.

  7. Aβ seeds resist inactivation by formaldehyde

    PubMed Central

    Fritschi, Sarah K.; Cintron, Amarallys; Ye, Lan; Mahler, Jasmin; Bühler, Anika; Baumann, Frank; Neumann, Manuela; Nilsson, K. Peter R.; Hammarström, Per; Walker, Lary C.; Jucker, Mathias

    2014-01-01

    Cerebral β-amyloidosis can be exogenously induced by the intracerebral injection of brain extracts containing aggregated β-amyloid (Aβ) into young, pre-depositing Aβ precursor protein- (APP) transgenic mice. Previous work has shown that the induction involves a prion-like seeding mechanism in which the seeding agent is aggregated Aβ itself. Here we report that the β-amyloid-inducing activity of Alzheimer’s disease (AD) brain tissue or aged APP-transgenic mouse brain tissue is preserved, albeit with reduced efficacy, after formaldehyde fixation. Moreover, spectral analysis with amyloid conformation-sensitive luminescent conjugated oligothiophene dyes reveals that the strain-like properties of aggregated Aβ are maintained in fixed tissues. The resistance of Aβ seeds to inactivation and structural modification by formaldehyde underscores their remarkable durability, which in turn may contribute to their persistence and spread within the body. The present findings can be exploited to establish the relationship between the molecular structure of Aβ aggregates and the variable clinical features and disease progression of AD even in archived, formalin-fixed autopsy material. PMID:25193240

  8. Aβ seeds resist inactivation by formaldehyde.

    PubMed

    Fritschi, Sarah K; Cintron, Amarallys; Ye, Lan; Mahler, Jasmin; Bühler, Anika; Baumann, Frank; Neumann, Manuela; Nilsson, K Peter R; Hammarström, Per; Walker, Lary C; Jucker, Mathias

    2014-10-01

    Cerebral β-amyloidosis can be exogenously induced by the intracerebral injection of brain extracts containing aggregated β-amyloid (Aβ) into young, pre-depositing Aβ precursor protein- (APP) transgenic mice. Previous work has shown that the induction involves a prion-like seeding mechanism in which the seeding agent is aggregated Aβ itself. Here we report that the β-amyloid-inducing activity of Alzheimer's disease (AD) brain tissue or aged APP-transgenic mouse brain tissue is preserved, albeit with reduced efficacy, after formaldehyde fixation. Moreover, spectral analysis with amyloid conformation-sensitive luminescent conjugated oligothiophene dyes reveals that the strain-like properties of aggregated Aβ are maintained in fixed tissues. The resistance of Aβ seeds to inactivation and structural modification by formaldehyde underscores their remarkable durability, which in turn may contribute to their persistence and spread within the body. The present findings can be exploited to establish the relationship between the molecular structure of Aβ aggregates and the variable clinical features and disease progression of AD even in archived, formalin-fixed autopsy material. PMID:25193240

  9. ACTION OF FORMALDEHYDE ON ENZYMES AND ON CERTAIN PBOTEIDS

    PubMed Central

    Bliss, C. L.; Novy, F. G.

    1899-01-01

    The following general conclusions may be drawn from the preceding work: Fibrin is altered by formaldehyde and is then less easily digested by pepsin and by trypsin. Papaïn is apparently unable to digest fibrin even when this is exposed to very weak formaldehyde (1:1000) for a very short time. The casein of milk, on contact with formaldehyde, undergoes rapid alteration and is as a result not coagulated by rennet, or but very slowly. Such altered casein, like similar fibrin, is not readily digested by the proteolytic ferments. The longer the formaldehyde acts on casein and on fibrin the more marked is the result. Pepsin is not affected by a one per cent solution of formaldehyde, even when the mixture has stood for four weeks. Even a five per cent solution of formaldehyde acting for three weeks has no effect on pepsin. Contrary results obtained by others are due to an alteration of the fibrin by the formaldehyde. A putrid solution of pepsin in distilled water one month old digests fibrin as readily as a fresh solution. Rennet is not affected even by a four per cent solution of formaldehyde acting for several weeks. The absence of coagulation at times is due to the action of formaldehyde on the casein of the milk and not on the rennet ferment. Papaïn is very quickly altered by formaldehyde, even in very dilute solution. Moreover, it is unable to digest fibrin that has been exposed to the action of a very dilute solution of formaldehyde for a short time. Trypsin is altered by formaldehyde to such an extent that digestion of fibrin will not take place, or but very slowly. The extent to which trypsin is affected by formaldehyde depends largely upon the amount of organic matter present, as well as on the amount of ferment in the solution. Amylopsin is not destroyed by very dilute solutions of formaldehyde, but stronger solutions decrease the activity of the ferment, and if used in sufficient concentration will destroy it completely. Ptyalin, like the diastatic ferment of

  10. Precursor polymers for the carbon coating of Au@ZnO multipods for application as active material in lithium-ion batteries.

    PubMed

    Oschmann, Bernd; Tahir, Muhammad Nawaz; Mueller, Franziska; Bresser, Dominic; Lieberwirth, Ingo; Tremel, Wolfgang; Passerini, Stefano; Zentel, Rudolf

    2015-06-01

    The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for carbonaceous materials, and thiol-containing repeating units as inorganic nanoparticle anchoring groups is reported. These polymers are used to coat Au@ZnO multipod heteroparticles with polymer brushes. IR spectroscopy and transmission electron microscopy prove the successful binding of the polymer onto the inorganic nanostructures. Thermogravimetric analysis is applied to compare the binding ability of the block and statistical copolymers. Subsequently, the polymer coating is transformed into a carbonaceous (partially graphitic) coating by pyrolysis. The obtained carbon coating is characterized by Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical performance of the carbon-coated particles (still 831 mAh g(-1) after 150 cycles) with respect to the uncoated ones (only 353 mAh g(-1) after 10 cycles). PMID:25598387

  11. α-Amylase monitoring by a novel amperometric biosensor based on Au electrode: its optimization, characterization, and application.

    PubMed

    Mengulluoglu, Umut; Altug, Cagri; Ertugrul, H Deniz; Yildiz, Abdulkerim; Ekici, E Melis; Dinckaya, Erhan

    2012-02-01

    A low-cost and sensitive amperometric biosensor was developed for the determination of α-amylase activity. The biosensor was constructed by immobilizing glucose oxidase-gelatin via glutaraldehyde on the Au electrode surface. Measurements were carried out chronoamperometrically at -0.7 V. Several parameters such as glucose oxidase activity, gelatin amount, and glutaraldehyde percentage for cross-linking were optimized. Optimum pH, optimum temperature, repeatability, and storage stabilities of the biosensor were identified. Under the optimum experimental conditions, a linear calibration curve was obtained for α-amylase between 0.819 and 13.110 U/ml. Sample analyses were carried out by detecting α-amylase activities in baker's yeast samples. PMID:21838534

  12. 21 CFR 177.1460 - Melamine-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Melamine-formaldehyde resins in molded articles...-formaldehyde resins in molded articles. Melamine-formaldehyde resins may be safely used as the food-contact...: (a) For the purpose of this section, melamine-formaldehyde resins are those produced when 1 mole...

  13. 21 CFR 177.1460 - Melamine-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Melamine-formaldehyde resins in molded articles...-formaldehyde resins in molded articles. Melamine-formaldehyde resins may be safely used as the food-contact...: (a) For the purpose of this section, melamine-formaldehyde resins are those produced when 1 mole...

  14. 21 CFR 177.1460 - Melamine-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Melamine-formaldehyde resins in molded articles...-formaldehyde resins in molded articles. Melamine-formaldehyde resins may be safely used as the food-contact...: (a) For the purpose of this section, melamine-formaldehyde resins are those produced when 1 mole...

  15. Proportional mortality patterns among chemical plant workers exposed to formaldehyde.

    PubMed Central

    Marsh, G M

    1982-01-01

    To examine the possible health risks associated with occupational exposure to formaldehyde a proportional mortality analysis was conducted on deaths occurring between 1950 and 1976 among 136 men who had been employed a month or more in one of five formaldehyde-related areas of a large chemical producing plant located in Springfield, Massachusetts, USA. Overall, no statistically significant excesses or deficits in proportional mortality were observed among the formaldehyde-exposed group based on comparisons with both United States men and men from the local county area. In addition, no important differences in mortality were observed among this group when comparisons were made with 456 male decedents from the same plant who had not had a month or more of formaldehyde exposure. Within the calendar period examined, no deaths from sinonasal cancer were observed among the chemical workers studied nor was mention made on any death certificate of sinonasal cancer as a contributory cause of death. No important excesses, trends, or patterns in cancer mortality were observed among white male formadelhyde-exposed workers when consideration was given to age and time period of death, type and duration of formaldehyde exposure, and the lapse period from the onset of the first formaldehyde-related job assignment. Although certain limitations of this study do not allow definite conclusions to be drawn, the results indicate no trends or patterns in proportional mortality that could be directly linked to exposures to formaldehyde. PMID:7138792

  16. Removal of formaldehyde from air using functionalized silica supports.

    PubMed

    Ewlad-Ahmed, Abdunaser M; Morris, Michael A; Patwardhan, Siddharth V; Gibson, Lorraine T

    2012-12-18

    This paper demonstrates the use of functionalized meso-silica materials (MCM-41 or SBA-15) as adsorbents for formaldehyde (H₂CO) vapor from contaminated air. Additionally new green nanosilica (GNs) materials were prepared via a bioinspired synthesis route and were assessed for removal of H₂CO from contaminated indoor air. These exciting new materials were prepared via rapid, 15 min, environmentally friendly synthesis routes avoiding any secondary pollution. They provided an excellent platform for functionalization and extraction of H₂CO demonstrating similar performance to the conventional meso-silica materials. To the authors' knowledge this is the first reported practical application of this material type. Prior to trapping, all materials were functionalized with amino-propyl groups which led to chemisorption of H₂CO; removing it permanently from air. No retention of H₂CO was achieved with nonfunctionalized material and it was observed that best extraction performance required a dynamic adsorption setup when compared to passive application. These results demonstrate the first application of GNs as potential adsorbents and functionalized meso-silica for use in remediation of air pollution in indoor air. PMID:23181357

  17. INSTRUCTIONS FOR OPERATING LBL FORMALDEHYDE SAMPLER

    SciTech Connect

    Fanning, L.Z.; Allen, J.R.; Miksch, R.R.

    1981-09-01

    The LBL formaldehyde sampler consists of two parts: 1) a pump box and 2) a small refrigerator housing sampling bubblers. The pump box contains two pumps, a timer, a flow controller, an electrical cord, and a ten-foot piece of tubing to connect the refrigerator to the pump box. The small refrigerator contains four columns of bubbler sampling trains attached to a metal plate. Two sampling trains each are plumbed in parallel to two sampling ports on the back of the refrigerator. The two sampling lines supplied are to be attached to these ports to allow two locations to be sampled at once (usually one indoor and one outdoor). The refrigerator also contains a rack for holding bubbler tubes. In the sampling process, air is drawn through a sampling line attached to the fitting at the back of the refrigerator and into a prlmary bubbler containing a trapping solution. This trapping solution can be distilled water or an aqueous solution of some compound that reacts with formaldehyde. From this bubbler the air goes through a second bubbler containing the same trapping solution as the first bubbler. (To maintain sample integrity, all parts that the air sample contacts are made of Teflon, polypropylene, and stainless steel.) The air then goes into the third bubbler, which contains no liquid. This bubbler contains a hypodermic needle that serves as a flow-control orifice. The hypodermic needle, in conjunction with the flow controller in the pump box, ensures a constant a flow rate. The refrigerator contains four columns of these sets of three bubblers. After samples have been collected, the bubbler bottoms are detached and the contents of the first and second bubblers in each column are poured together, capped, and labeled. The use of a refrigerated primary and secondary bubbler whose contents are combined at the end of a sampling period ensures 95% collection efficiency. After the bubbler tubes are capped and labeled, they are stored either in the rack supplied in the

  18. The Development of Conductive Elements for the Selective Detection of Formaldehyde and Cotinine

    NASA Astrophysics Data System (ADS)

    Antwi-Boampong, Sadik

    The development of new materials and techniques presents an opportunity to revisit old problems. Innovations in materials engineering revolutionize the status quo by expanding the tool kit needed to develop robust solutions to complex problems. Challenges that had hitherto been intractable become surmountable; previously established methods are significantly enhanced; fresh impetus is injected into the materials design engine. In one way or another, every scientist contributes to this dynamic creative process where ideas are incubated and developed through fundamental research that culminates in compelling findings applicable in various realms of science. The work presented herein embodies this ethos. Our investigations have applied the relatively nascent technology of molecular imprinting to develop sensing elements for detection of cotinine and formaldehyde. Additionally, we have used different polymer systems to address the inherent limitations of conventional materials using a simple, cost-effective and efficient materials approach. Specifically, in Part I, we investigate molecular imprinting of nylon-6, polyvinylphenol and ElvamideRTM, with cotinine. We examine the capacity of these materials as polymer hosts for molecular imprinting by studying the effect of cotinine imprinting on their nanomechanical properties. By monitoring variations in mechanical properties induced by cotinine templating, we determine the factors critical for effective imprinting and ultimately demonstrate that polyvinylphenol is the most suitable polymer host. Based on these results, we develop a cotinine-imprinted polyvinylphenol-single walled carbon nanotube sensor that readily detects cotinine. Using electrical, spectral and chromatographic characterization, we rigorously demonstrate the enhanced affinity programmed into the sensing layer via molecular imprinting. Part II is dedicated to a familiar problem: formaldehyde sensing. While this challenge has been a trope of the

  19. Photochemical production of formaldehyde in earth's primitive atmosphere

    NASA Astrophysics Data System (ADS)

    Pinto, J. P.; Gladstone, G. R.; Yung, Y. L.

    1980-10-01

    Formaldehyde could have been produced by photochemical reactions in the earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 100 billion moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.

  20. Photochemical production of formaldehyde in earth's primitive atmosphere

    NASA Technical Reports Server (NTRS)

    Pinto, J. P.; Gladstone, G. R.; Yung, Y. L.

    1980-01-01

    Formaldehyde could have been produced by photochemical reactions in the earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 100 billion moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.

  1. Formaldehyde: a candidate toxic air contaminant. Final report

    SciTech Connect

    Frye, B.; Parker, T.

    1988-03-01

    Formaldehyde (HCHO) is a gas widely used in adhesives and resins, textiles, embalming fluids, fungicides, air fresheners, and cosmetics. It is directly emitted into the ambient outdoor air from vehicular and stationary sources, and is also produced in the atmosphere from other substances by photochemical smog processes. The International Agency for Research on Cancer (IARC) has determined that there is sufficient evidence for carcinogenicity of formaldehyde to animals, and limited evidence for carcinogenicity to humans. EPA classifies formaldehyde as a probable human carcinogen with a one in a million risk concentration of 0.08 ppb.

  2. Measurement of formaldehyde in clean air

    SciTech Connect

    Neitzert, V.; Seiler, W.

    1981-01-01

    A method for the measurement of small amounts of formaldehyde in air has been developed. The method is based on the derivatization of HCHO with 2.4-Denetrophenylhydragine, forming 2.4-Dentrophylhydragine, measured with GC-ECD-technique. HCHO is preconcentrated using a cryogenic sampling technique. The detection limit is 0.05 ppbv for a sampling volume of 200 liter. The method has been applied for measurements in continental and marine air masses showing HCHO mixing ratios of 0.4--5.0 ppbv and 0.2--1.0 ppbv, respectively. HCHO mixing ratios show diurnal variations with maximum values during the early afternoon and minimum values during the early morning. In continental air, HCHO mixing ratios are positively correlated with CO and SO/sub 2/, indicating anthropogenic HCHO sources which are estimated to be 6--11 x 10/sup 12/g/year/sup -1/ on a global scale.

  3. High efficiency annual denuder for formaldehyde monitoring

    SciTech Connect

    Cecchini, F.; Febo, A.; Possanzini, M.

    1985-01-01

    A practical and correct methodology for evaluating CH/sub 2/O in air without sampling artifact formation is presented. Formaldehyde is collected on an annual denuder coated with bisulfite-triethanolamine. The sorbent layer is extracted with water and the solution analyzed by the chromotropic acid (CTA) procedure. Sorption efficiency and loading capacity have been investigated along with storage stability. Results of laboratory validation studies have indicated that a small annual denuder was able to sample about 300 ..mu..g CH/sub 2/O without an appreciable decrease in the initial collection efficiency (99% at 2.5 1 min/sup -1/). Tests on storage stability before and after exposure have also demonstrated that both oxidation of bisulfite and release of CH/sub 2/O did not occur for time periods as long as 1 month.

  4. Chronic respiratory effects of indoor formaldehyde exposure

    SciTech Connect

    Krzyzanowski, M.; Quackenboss, J.J.; Lebowitz, M.D.

    1990-01-01

    The relation of chronic respiratory symptoms and pulmonary function to formaldehyde (HCHO) in homes was studied in a sample of 298 children (6-15 years of age) and 613 adults. HCHO measurements were made with passive samplers two one-week periods. Data on chronic cough and phlegm, wheeze, attacks of breathlessness, and doctor diagnoses of chronic bronchitis and asthma were collected with self-completed questionnaires. Peak expiratory flow rates (PEFR) were obtained during the evenings and mornings for up to 14 consecutive days for each individual. Significantly greater prevalence rates of asthma and chronic bronchitis were found in children from houses with HCHO levels 60-120 ppb than in those less exposed, especially in children also exposed to environmental tobacco smoke. In children, levels of PEFR linearly decreased with HCHO exposure, with estimated decrease due to 60 ppb of HCHO equivalent to 22% of PEFR level in nonexposed children.

  5. Ag/Au mixed sites promote oxidative coupling of methanol on the alloy surface.

    PubMed

    Xu, Bingjun; Siler, Cassandra G F; Madix, Robert J; Friend, Cynthia M

    2014-04-14

    Nanoporous gold, a dilute alloy of Ag in Au, activates molecular oxygen and promotes the oxygen-assisted catalytic coupling of methanol. Because this trace amount of Ag inherent to nanoporous gold has been proposed as the source of oxygen activation, a thin film Ag/Au alloy surface was studied as a model system for probing the origin of this reactivity. Thin alloy layers of Ag(x)Au(1-x), with 0.15≤x≤0.40, were examined for dioxygen activation and methanol self-coupling. These alloy surfaces recombine atomic oxygen at different temperatures depending on the alloy composition. Total conversion of methanol to selective oxidation products, that is, formaldehyde and methyl formate, was achieved at low initial oxygen coverage and at low temperature. Reaction channels for methyl formate formation occurred on both Au and Au/Ag mixed sites with a ratio, as was predicted from the local 2-dimensional composition. PMID:24633724

  6. IRIS Toxicological Review of Formaldehyde (Inhalation) (External Review Draft 2010)

    EPA Science Inventory

    UPDATE EPA is currently revising its Integrated Risk Information System (IRIS) assessment of formaldehyde to address the 2011 NAS peer review recommendations. This assessment addresses both noncancer and cancer human health effects that are relevant to assessing ...

  7. Ion laser isotope enrichment by photo-predissociation of formaldehyde

    DOEpatents

    Marling, John B.

    1977-06-17

    Enrichment of carbon, hydrogen and/or oxygen isotopes by means of isotopically selective photo-predissociation of formaldehyde is achieved by irradiation with a fixed frequency ion laser, specifically, a neon, cadmium, or xenon ion laser.

  8. PHOTOCHEMICAL REACTIONS AMONG FORMALDEHYDE, CHLORINE, AND NITROGEN DIOXIDE IN AIR

    EPA Science Inventory

    Photochemical reactions among chlorine, nitrogen dioxide, and formaldehyde were studied, using parts-per-million concentrations in 1 atm of air. The reactant mixtures were irradiated by ultraviolet fluorescent lamps and simultaneously analyzed by the Fourier transform infrared te...

  9. ETV REPORT: CERTEK, INC. 1414RH FORMALDEHYDE GENERATOR/NEUTRALIZER

    EPA Science Inventory

    The Environmental Technology Verification report discusses the technology and performance of the 1414RH Formaldehyde Generator/Neuralizer, a biological decontamination device manufactured by CERTEK, Inc. The unit was tested by evaluating its ability to decontaminate seven types ...

  10. Microbial urea-formaldehyde degradation involves a new enzyme, methylenediurease.

    PubMed

    Jahns, T; Schepp, R; Siersdorfer, C; Kaltwasser, H

    1998-01-01

    The enzymic mechanism of metabolization of urea-formaldehyde condensation products (methyleneureas; MU) and the fate of the degradation products ammonium, urea and formaldehyde were studied in bacteria isolated from garden soil, which were able to use methyleneureas as the sole source of nitrogen for growth. An organism identified as Ochrobactrum anthropi completely degraded methylenediurea (MDU) and dimethylenetriurea (DMTU) to urea, ammonia, formaldehyde and carbon dioxide. An enzyme designated as methylenediurease (methylenediurea deiminase; MDUase) was responsible for the degradation of both MDU and DMTU as well as higher polymerized MU. Growth on MU as the nitrogen source specifically induced the synthesis of this enzyme, which seems to be located in the periplasm of the bacterium. Under these growth conditions, urease as well as NAD-specific formaldehyde and formiate dehydrogenase were expressed to high levels, efficiently using the products of MU degradation, and high-affinity transport systems for urea and ammonia were synthesized scavenging the environment for these products. PMID:10526991

  11. Formaldehyde Surface Distributions and Variability in the Mexico City Basin

    NASA Astrophysics Data System (ADS)

    Junkermann, W.; Mohr, C.; Steinbrecher, R.; Ruiz Suarez, L.

    2007-05-01

    Formaldehyde ambient air mole fractions were measured throughout the dry season in March at three different locations in the Mexico City basin. The continuously running instruments were operated at Tenago del Aire, a site located in the Chalco valley in the southern venting area of the basin, at the Intituto Mexicano del Petroleo (IMP) in the northern part of the city and about 30 km north of the city at the campus of the Universidad Tecnològica de Tecamac (UTTEC). The technique used is the Hantzsch technology with a time resolution of 2 minutes and a detection limit of 100 ppt. Daily maxima peaked at 35 ppb formaldehyde in the city and about 15 to 20 ppb at the other sites. During night formaldehyde levels dropped to about 5 ppb or less. It is evident that the observed spatial and temporal variability in near surface formaldehyde distributions is strongly affected by local and regional advection processes.

  12. A Density Functional Theory Study of Formaldehyde Adsorption on Ceria

    SciTech Connect

    Mei, Donghai; Deskins, N. Aaron; Dupuis, Michel

    2007-11-01

    Molecular adsorption of formaldehyde on the stoichiometric CeO2(111) and CeO2(110) surfaces was studied using periodic density functional theory. Two adsorption modes (strong chemisorbed and weak physisorbed) were identified on both surfaces. This is consistent with recent experimental observations. On the (111) surface, formaldehyde strongly chemisorbs with an adsorption energy of 0.86 eV to form a dioxymethylene-like structure, in which a surface O lifts from the surface to bind with the C of formaldehyde. A weak physisorbed state with adsorption energy of 0.28 eV was found with the O of formaldehyde interacting with a surface Ce. On the (110) surface, dioxymethyelene formation was also observed, with an adsorption energy of 1.31 eV. The weakly adsorbed state of formaldehyde on the (110) surface was energetically comparable to the weak adsorption state on the (111) surface, but adsorption occurred through a formaldehyde C and surface O interaction. Analysis of the local density of states and charge density differences after adsorption shows that strong covalent bonding occurs between the C of formaldehyde and surface O when dioxymethylene forms. Calculated vibrational frequencies also confirm dioxymethylene formation. Our results also show that as the coverage increases, the adsorption of formaldehyde on the (111) surface becomes weak, but is nearly unaffected on the (110) surface. This work was supported by a Laboratory Directed Research and Development (LDRD) project of the Pacific Northwest National Laboratory (PNNL). The computations were performed using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory, which is a U.S. Department of Energy national scientific user facility located at PNNL in Richland, Washington. Computing time was made under a Computational Grand Challenge “Computational Catalysis”. Part of the computing time was also granted by the National Energy Research Scientific Computing

  13. Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

    NASA Astrophysics Data System (ADS)

    Schwemmer, G.; Yakshin, M.; Prasad, C.; Hanisco, T.; Mylapore, A. R.; Hwang, I. H.; Lee, S.

    2016-06-01

    We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO) fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

  14. Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application

    NASA Astrophysics Data System (ADS)

    Karamipour, Sh.; Sadjadi, M. S.; Farhadyar, N.

    2015-09-01

    Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au3+ with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used L-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of L-cysteine and folic acid to Fe3O4@Au nanoparticles.

  15. Nano-scale Au supported on Fe3O4: characterization and application in the catalytic treatment of 2,4-dichlorophenol

    NASA Astrophysics Data System (ADS)

    Gómez-Quero, Santiago; Cárdenas-Lizana, Fernando; Keane, Mark A.

    2012-07-01

    Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe3O4 have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on α-Fe2O3 with subsequent temperature-programmed reduction at 673 K (Au/Fe3O4-step); (ii) direct deposition of Au on Fe3O4 (Au/Fe3O4-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe3O4-dir relative to Au/Fe3O4-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe2O3. Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe3O4-step delivered a two-fold higher rate (2 × 10-4 molCl h-1 mAu-2) when compared with Au/Fe3O4-dir. This unprecedented selectivity response is attributed to activation of the ortho-C-Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.

  16. Formaldehyde Levels in Traditional and Portable Classrooms: A Pilot Investigation.

    PubMed

    Lucas, Isabela Ribeiro; Kowalski, Peter; Callahan, David B; Noonan, Gary P; Moffett, Daphne B; Olson, David H; Malilay, Josephine

    2016-03-01

    The pilot study discussed in this article assessed formaldehyde levels in portable classrooms (PCs) and traditional classrooms the authors evaluated formaldehyde levels in day and overnight indoor air (TCs) and explored factors influencing indoor air quality (e.g., carbon dioxide, temperature, and relative humidity). In a cross-sectional design, samples from nine PCs renovated within three years previously and three TCs in a school district in metropolitan Atlanta, Georgia. Formaldehyde levels ranged from 0.0068 to 0.038 parts per million (ppm). In both types of classroom, overnight formaldehyde median levels (PCs = 0.018 ppm; TCs = 0.019 ppm) were higher than day formaldehyde median levels (PCs = 0.011 ppm; TCs = 0.016 ppm). Carbon dioxide levels measured 470-790 ppm at 7:00 a.m. and 470-1800 ppm at 4:00 p.m. Afternoon medians were higher in TCs (1,400 ppm) than in PCs (780 ppm). Consistent with previous studies, formaldehyde levels were similar among PCs and TCs. Reducing carbon dioxide levels by improving ventilation is recommended for classrooms. PMID:27197349

  17. Formaldehyde emissions from ventilation filters under different relative humidity conditions.

    PubMed

    Sidheswaran, Meera; Chen, Wenhao; Chang, Agatha; Miller, Robert; Cohn, Sebastian; Sullivan, Douglas; Fisk, William J; Kumagai, Kazukiyo; Destaillats, Hugo

    2013-05-21

    Formaldehyde emissions from fiberglass and polyester filters used in building heating, ventilation, and air conditioning (HVAC) systems were measured in bench-scale tests using 10 and 17 cm(2) coupons over 24 to 720 h periods. Experiments were performed at room temperature and four different relative humidity settings (20, 50, 65, and 80% RH). Two different air flow velocities across the filters were explored: 0.013 and 0.5 m/s. Fiberglass filters emitted between 20 and 1000 times more formaldehyde than polyester filters under similar RH and airflow conditions. Emissions increased markedly with increasing humidity, up to 10 mg/h-m(2) at 80% RH. Formaldehyde emissions from fiberglass filters coated with tackifiers (impaction oils) were lower than those from uncoated fiberglass media, suggesting that hydrolysis of other polymeric constituents of the filter matrix, such as adhesives or binders was likely the main formaldehyde source. These laboratory results were further validated by performing a small field study in an unoccupied office. At 80% RH, indoor formaldehyde concentrations increased by 48-64%, from 9-12 μg/m(3) to 12-20 μg/m(3), when synthetic filters were replaced with fiberglass filtration media in the HVAC units. Better understanding of the reaction mechanisms and assessing their overall contributions to indoor formaldehyde levels will allow for efficient control of this pollution source. PMID:23597095

  18. Clinical evaluation of patients with complaints related to formaldehyde exposure

    SciTech Connect

    Imbus, H.R.

    1985-12-01

    Formaldehyde is a very widely used chemical in our present society and one with which every physician has had a first-hand experience in his early days of training in the anatomy laboratory. The National Institute of Occupational Safety and Health lists 52 occupations that expose people to formaldehyde. In recent years, however, the increasing use of formaldehyde resins in the production of building materials such as particleboard and urea-formaldehyde foam insulation has resulted in exposures of large numbers of people in nonoccupational settings. Consumer products such as cosmetics, cigarettes, textiles, furniture, draperies, and preservatives release formaldehyde. It is present in the outdoor atmosphere from products of combustion and automobile exhaust and likewise in the home from such things as gas cooking. These more widespread and increased exposures have resulted in concern regarding potential health effects. Therefore, it is likely that physicians have or will encounter patients who wish evaluations of a present or potential health effect from formaldehyde. This article is for the purpose of providing assistance in such evaluation.110 references.

  19. Histomorphometric comparison after fixation with formaldehyde or glyoxal

    PubMed Central

    Wang, YN; Lee, K; Pai, S; Ledoux, WR

    2014-01-01

    Formaldehyde has long been the fixative of choice for histological examination of tissue. The use of alternatives to formaldehyde has grown, however, owing to the serious hazards associated with its use. Companies have striven to maintain the morphological characteristics of formaldehyde-fixed tissue when developing alternatives. Glyoxal-based fixatives now are among the most popular formaldehyde alternatives. Although there are many studies that compare staining quality and immunoreactivity, there have been no studies that quantify possible structural differences. Histomorphometric analysis commonly is used to evaluate diseased tissue. We compared fixation with formaldehyde and glyoxal with regard to the histomorphological properties of plantar foot tissue using a combination of stereological methods and quantitative morphology. We measured skin thickness, interdigitation index, elastic septa thickness, and adipocyte area and diameter. No significant differences were observed between formaldehyde and glyoxal fixation for any feature measured. The glyoxal-based fixative used therefore is a suitable fixative for structural evaluation of plantar soft tissue. Measurements obtained from the glyoxal-fixed tissue can be combined with data obtained from formalin-fixed for analysis. PMID:20854226

  20. Health risks from indoor formaldehyde exposures in northwest weatherized residences

    SciTech Connect

    Mellinger, P.J.; Sever, L.E.

    1986-10-01

    Conflicting opinions on the potential hazards associated with formaldehyde exposure triggered a national workshop to address the toxicological questions concerning the health effects of formaldehyde. Since quantitative human data are not available to derive a dose-response curve for formaldehyde risk assessment, nonhuman data are used. In the case of formaldehyde, data from animals exposed to high concentrations are used to estimate human risk at much lower concentrations. This study presents the several steps that make up a risk assessment and examines any additional data that might alter significantly the risk estimates presented in the 1984 EIS. Rat inhalation chronic bioassay data from a study sponsored by the Chemical Industry Institute of Toxicology (CIIT) have been used to develop a risk equation that was subsequently used by BPA in its EIS. The CIIT data base remains the only acceptable animal data that can support the estimation of a dose-response curve. The development of mathematical models continues with a great deal of energy, and the use of different models is largely responsible for the great variability of the formaldehyde risk estimates. While one can calculate different values for carcinogenic risk associated with formaldehyde exposure than were presented earlier in the BPA EIS, they are not likely to be any better.

  1. Fabrication of High Sensitive Immunochromato Kit Using Au Colloid

    NASA Astrophysics Data System (ADS)

    Okamoto, Koji

    Au colloid have characteristics of surface plasmon resonance with absorption at 500 nm~600 nm wavelength. Surface on the citric acid Au colloid can be conjugated with protein eg. antibody. Various particle size of Au colloid makes it high sensitive immunochromato as diagnostics. High sensitive immunochromato will be useful for application of cancer marker eg. prostate specific antigen and influenza early diagnosis.

  2. Reaction mechanism for methanol oxidation on Au(1 1 1): A density functional theory study

    NASA Astrophysics Data System (ADS)

    Liu, Shuping; Jin, Peng; Zhang, Donghui; Hao, Ce; Yang, Xueming

    2013-01-01

    The microscopic reaction mechanism for methanol oxidation on Au(1 1 1) surface has been thoroughly investigated by means of density functional theory (DFT) computations. The adsorption geometries and energies were obtained for all the adsorbates, including the reactants, the products, and various possible intermediates on the metal. According to different oxygen conditions, we propose two possible reaction pathways for methanol oxidation on Au(1 1 1): (1) HCHO esterification: the intermediate formaldehyde and methoxy couple to yield methyl formate at low oxygen coverage or without the presence of oxygen atoms; (2) HCHO oxidation: the formaldehyde is oxidized to form formate at high oxygen coverage, which further dissociates to give CO2. Our study emphasizes the critical role of oxygen coverage during the methanol oxidation reaction, and can perfectly explain the difference in product distributions observed in previous experiments.

  3. Self-assembly of thiolated cyanine aggregates on Au(111) and Au nanoparticle surfaces

    NASA Astrophysics Data System (ADS)

    Menéndez, Guillermo O.; Cortés, Emiliano; Grumelli, Doris; Méndez de Leo, Lucila P.; Williams, Federico J.; Tognalli, Nicolás G.; Fainstein, Alejandro; Vela, María Elena; Jares-Erijman, Elizabeth A.; Salvarezza, Roberto C.

    2012-01-01

    Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show that CNN species adsorb on the Au surfaces by forming thiolate-Au bonds. We found that the J-aggregates are preferentially adsorbed on the Au(111) surface directly from the solution while adsorbed CNN monomers cannot organize into aggregates on the substrate surface. These results indicate that the CNN-Au interaction is not able to disorganize the large J-aggregates stabilized by π-π stacking to optimize the S-Au binding site but it is strong enough to hinder the π-π stacking when CNNs are chemisorbed as monomers. The optical properties of the J-aggregates remain active after adsorption. The possibility of covalently bonding CNN J-aggregates to Au planar surfaces and Au nanoparticles controlling the J-aggregate/Au distance opens a new path regarding their improved stability and the wide range of biological applications of both CNN and AuNP biocompatible systems.Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show

  4. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds.

    PubMed

    Keast, V J; Barnett, R L; Cortie, M B

    2014-07-30

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications. PMID:25001413

  5. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Keast, V. J.; Barnett, R. L.; Cortie, M. B.

    2014-07-01

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications.

  6. Transport de particules massives dans un fluide turbulent: Application a l'erosion due au sable sur les parois d'une turbine hydraulique

    NASA Astrophysics Data System (ADS)

    Bergeron, Stephen

    Le transport de particules massives par un champ turbulent est un vaste domaine de la mécanique des fluides. Il possède de nombreuses applications comme par exemple le transport de sable dans une turbine hydraulique. En raison de la dureté des grains de quartz et des grandes vitesses de collision avec les parois métalliques, un phénomène d'érosion intensif se produit. Les dommages résultants peuvent diminuer le rendement de la turbine au cours des quelques mois suivant la mise en opération. L'objectif de cette thèse est de mettre au point un outil permettant de prédire ces zones d'érosion. Ce projet de recherche en contexte industriel a été réalisé en collaboration avec la compagnie General Electric Hydro du Canada. Dans un régime hautement turbulent, il est possible d'obtenir une expression suffisamment générale en utilisant une formulation partiellement empirique: l'équation de Basset- Boussinesq-Oseen modifiée. Ce choix de modèle tient compte du niveau de précision recherché et de la méthode numérique employée afin de résoudre la phase fluide. Il permet aussi d'éliminer plusieurs ambiguïtés fréquemment rencontrées dans la littérature et implementées dans certains codes commerciaux courants. La formulation mathématique du problème est effectuée dans un espace mixte Euler-Lagrange. Les paramètres dynamiques sont relies au type de particules et à l'intensité de la turbulence. Le code numérique résultant est le plus performant développé à ce jour (août 1998). Les trajectoires de plusieurs centaines de milliers de particules peuvent être simulées et visualisées de manière interactive sur une station de travail (SGI R4K, R8K et R10K). L'utilisateur du logiciel est libre de se déplacer dans l'espace à l'aide d'un environnement similaire a un ``simulateur de vol''. Il peut ainsi analyser les détails du processus d'érosion de même que l'écoulement du fluide dans la turbine. Les zones d'érosion obtenues à l

  7. Au-Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment.

    PubMed

    Jiang, Tongtong; Song, Jiangluqi; Zhang, Wenting; Wang, Hao; Li, Xiaodong; Xia, Ruixiang; Zhu, Lixin; Xu, Xiaoliang

    2015-10-01

    Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents. PMID:26371629

  8. Airborne tunable diode laser measurements of formaldehyde

    NASA Astrophysics Data System (ADS)

    Fried, Alan; Wert, Bryan P.; Henry, Bruce; Drummond, James R.

    1999-09-01

    Accurate measurements of formaldehyde (CH 2O) in the atmosphere are essential to further our understanding of various atmospheric cycles involving hydrogen and carbon-containing species. Comparisons among independent measurements of this gas and between measurements and model calculations have raised numerous questions regarding the veracity of both endeavors. The present paper describes a long-term effort by our group to develop and employ tunable diode laser absorption spectroscopy (TDLAS) for highly accurate measurements of this gas on both ground-based and aircraft platforms. A highly sensitive and selective TDLAS system, which has successfully flown on three different aircraft campaigns, will be described. Many new hardware and software features, which have been implemented, now make it possible to detect ambient CH 2O concentrations as low as 55 parts-per-trillion employing a 20-s integration time. This paper will also discuss the many aspects associated with high accuracy and its verification, including a brief discussion of our aircraft sampling system and inlet surface effects.

  9. Chronic respiratory effects of indoor formaldehyde exposure

    SciTech Connect

    Krzyzanowski, M.; Quackenboss, J.J.; Lebowitz, M.D. )

    1990-08-01

    The relation of chronic respiratory symptoms and pulmonary function to formaldehyde (HCHO) in homes was studied in a sample of 298 children (6-15 years of age) and 613 adults. HCHO measurements were made with passive samplers during two 1-week periods. Data on chronic cough and phlegm, wheeze, attacks of breathlessness, and doctor diagnoses of chronic bronchitis and asthma were collected with self-completed questionnaires. Peak expiratory flow rates (PEFR) were obtained during the evenings and mornings for up to 14 consecutive days for each individual. Significantly greater prevalence rates of asthma and chronic bronchitis were found in children from houses with HCHO levels 60-120 ppb than in those less exposed, especially in children also exposed to environmental tobacco smoke. In children, levels of PEFR decreased linearly with HCHO exposure, with the estimated decrease due to 60 ppb of HCHO equivalent to 22% of PEFR level in nonexposed children. The effects in asthmatic children exposed to HCHO below 50 ppb were greater than in healthy ones. The effects in adults were less evident: decrements in PEFR due to HCHO over 40 ppb were seen only in the morning, and mainly in smokers.

  10. Gold(III) Mediated Activation and Transformation of Methane on Au1-Doped Vanadium Oxide Cluster Cations AuV2O6(.).

    PubMed

    Li, Zi-Yu; Li, Hai-Fang; Zhao, Yan-Xia; He, Sheng-Gui

    2016-08-01

    Gold in the +III oxidation state (Au(III)) has been proposed as a promising species to mediate challenging chemical reactions. However, it is difficult to characterize the chemistry of individual Au(III) species in condensed-phase systems mainly due to the interference from the Au(I) counterpart. Herein, by doping Au atoms into gas-phase vanadium oxide clusters, we demonstrate that the Au(III) cation in the AuV2O6(+) cluster is active for activation and transformation of methane, the most stable alkane molecule, into formaldehyde under mild conditions. In contrast, the AuV2O6(+) cluster isomers with the Au(I) cation can only absorb CH4. The clusters were generated by laser ablation and mass selected to react with CH4, CD4, or CH2D2 in an ion trap reactor. The reactivity was characterized by mass spectrometry and quantum chemistry calculations. The structures of the reactant and product ions were identified by using collision-induced and 425 nm photo-induced dissociation techniques. PMID:27385079

  11. Passive flux sampler for measurement of formaldehyde emission rates

    NASA Astrophysics Data System (ADS)

    Shinohara, Naohide; Fujii, Minoru; Yamasaki, Akihiro; Yanagisawa, Yukio

    A new passive flux sampler (PFS) was developed to measure emission rates of formaldehyde and to determine emission sources in indoor environments. The sampler consisted of a glass Petri dish containing a 2,4-dinitrophenyl hydrazine (DNPH)-impregnated sheet. At the start of sampling, the PFS was placed with the open face of the dish on each of the indoor materials under investigation, such as flooring, walls, doors, closets, desks, beds, etc. Formaldehyde emitted from a source material diffused through the inside of the PFS and was adsorbed onto the DNPH sheet. The formaldehyde emission rates could be determined from the quantities adsorbed. The lower determination limits were 9.2 and 2.3 μg m -2 h -1 for 2- and 8-h sampling periods. The recovery rate and the precision of the PFS were 82.9% and 8.26%, respectively. The emission rates measured by PFS were in good agreement with the emission rates measured by the chamber method ( R2=0.963). This shows that it is possible to take measurements of the formaldehyde emission rates from sources in a room and to compare them. In addition, the sampler can be used to elucidate the emission characteristics of a source by carrying out emission measurements with different air-layer thicknesses inside the PFS and at different temperatures. The dependency of the emission rate on the thickness of the air layer inside the PFS indicated whether the internal mass transfer inside the source material or the diffusion in the gas-phase boundary layer controlled the formaldehyde emission rate from a material. In addition, as a pilot study, the formaldehyde emission rates were measured, and the largest emission source of formaldehyde could be identified from among several suspected materials in a model house by using the PFS.

  12. Fabrication and Performance of Noble Metal Promoted Birnessite Catalysts for Complete Oxidation of Formaldehyde at Low Temperatures.

    PubMed

    Liu, Linlin; Tian, Hua; He, Junhui; Wang, Donghui; Ma, Chunyan; Yang, Qiaowen

    2015-04-01

    Noble metal (Au, Ag, Pd and Pt) promoted birnessite (Bir) catalysts were successfully prepared and tested for catalytic oxidation of formaldehyde (HCHO). The catalysts were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), hydrogen temperature programmed reduction (H2-TPR), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and N2 adsorption-desorption. The activities of noble metal (Au, Ag, Pd and Pt) promoted birnessite catalysts follow the order of 1.0Pt/Bir > 1.0Pd/Bir > Bir > 1.0Ag/Bir > 1.0Au/Bir, revealing that the loading of Pd and Pt improves the catalytic activity of birnessite, but the loading of Ag and Au slightly decreases the catalytic activity of birnessite. Effects of the Pt loading amount were also investigated on the activity of Pt/Bir catalysts for HCHO oxidation. Pt/Bir with a Pt loading of 1.5 wt% (1.5 Pt/Bir), which has the best reduction properties, was found to be the most efficient catalyst. Over this catalyst, HCHO could be completely oxidized into CO2 and H2O at 70°. 1.5 Pt/Bir also shows good catalytic stability under the HCHO oxidation atmosphere. The differences in the catalytic activity of these materials are largely attributed to their reducibility as well as the dispersion of metal nanoparticles, but are not directly related to their specific surface areas. PMID:26353510

  13. Au nanorod helical superstructures with designed chirality.

    PubMed

    Lan, Xiang; Lu, Xuxing; Shen, Chenqi; Ke, Yonggang; Ni, Weihai; Wang, Qiangbin

    2015-01-14

    A great challenge for nanotechnology is to controllably organize anisotropic nanomaterials into well-defined three-dimensional superstructures with customized properties. Here we successfully constructed anisotropic Au nanorod (AuNR) helical superstructures (helices) with tailored chirality in a programmable manner. By designing the 'X' pattern of the arrangement of DNA capturing strands (15nt) on both sides of a two-dimensional DNA origami template, AuNRs functionalized with the complementary DNA sequences were positioned on the origami and were assembled into AuNR helices with the origami intercalated between neighboring AuNRs. Left-handed (LH) and right-handed (RH) AuNR helices were conveniently accomplished by solely tuning the mirrored-symmetric 'X' patterns of capturing strands on the origami. The inter-rod distance was precisely defined as 14 nm and inter-rod angle as 45°, thus a full helix contains 9 AuNRs with its length up to about 220 nm. By changing the AuNR/origami molar ratio in the assembly system, the average number of AuNR in the helices was tuned from 2 to 4 and 9. Intense chiroptical activities arose from the longest AuNR helices with a maximum anisotropy factor of ∼0.02, which is highly comparable to the reported macroscopic AuNR assemblies. We expect that our strategy of origami templated assembly of anisotropic chiral superstructures would inspire the bottom-up fabrication of optically active nanostructures and shed light on a variety of applications, such as chiral fluids, chiral signal amplification, and fluorescence combined chiral spectroscopy. PMID:25516475

  14. Advanced Catalysts for the Ambient Temperature Oxidation of Carbon Monoxide and Formaldehyde

    NASA Technical Reports Server (NTRS)

    Nalette, Tim; Eldridge, Christopher; Yu, Ping; Alpetkin, Gokhan; Graf, John

    2010-01-01

    The primary applications for ambient temperature carbon monoxide (CO) oxidation catalysts include emergency breathing masks and confined volume life support systems, such as those employed on the Shuttle. While Hopcalite is typically used in emergency breathing masks for terrestrial applications, in the 1970s, NASA selected a 2% platinum (Pt) on carbon for use on the Shuttle since it is more active and also more tolerant to water vapor. In the last 10-15 years there have been significant advances in ambient temperature CO oxidation catalysts. Langley Research Center developed a monolithic catalyst for ambient temperature CO oxidation operating under stoichiometric conditions for closed loop carbon dioxide (CO2) laser applications which is also advertised as having the potential to oxidize formaldehyde (HCHO) at ambient temperatures. In the last decade it has been discovered that appropriate sized nano-particles of gold are highly active for CO oxidation, even at sub-ambient temperatures, and as a result there has been a wealth of data reported in the literature relating to ambient/low temperature CO oxidation. In the shorter term missions where CO concentrations are typically controlled via ambient temperature oxidation catalysts, formaldehyde is also a contaminant of concern, and requires specially treated carbons such as Calgon Formasorb as untreated activated carbon has effectively no HCHO capacity. This paper examines the activity of some of the newer ambient temperature CO and formaldehyde (HCHO) oxidation catalysts, and measures the performance of the catalysts relative to the NASA baseline Ambient Temperature Catalytic Oxidizer (ATCO) catalyst at conditions of interest for closed loop trace contaminant control systems.

  15. Formaldehyde emission—Comparison of different standard methods

    NASA Astrophysics Data System (ADS)

    Risholm-Sundman, Maria; Larsen, Annelise; Vestin, Ewa; Weibull, Anders

    The emission of formaldehyde is an important factor in the evaluation of the environmental and health effects of wood-based board materials. This article gives a comparison between commonly used European test methods: chamber method [EN 717-1, 2004. Wood-based panels—determination of formaldehyde release—Part 1: formaldehyde emission by the chamber method. European Standard, October 2004], gas analysis method [EN 717-2, 1994. Wood-based panels—determination of formaldehyde release—Part 2: formaldehyde release by the gas analysis method, European Standard, November 1994], flask method [EN 717-3, 1996. Wood-based panels—determination of formaldehyde release—Part 3: formaldehyde release by the flask method, European Standard, March 1996], perforator method [EN 120, 1993. Wood based panels—determination of formaldehyde content—extraction method called perforator method, European Standard, September 1993], Japanese test methods: desiccator methods [JIS A 1460, 2001. Building boards. Determination of formaldehyde emission—desiccator method, Japanese Industrial Standard, March 2001 and JAS MAFF 233, 2001] and small chamber method [JIS A 1901, 2003. Determination of the emission of volatile organic compounds and aldehydes for building products—small chamber method, Japanese Industrial Standard, January 2003], for solid wood, particleboard, plywood and medium density fiberboard. The variations between the results from different methods can partly be explained by differences in test conditions. Factors like edge sealing, conditioning of the sample before the test and test temperature have a large effect on the final emission result. The Japanese limit for F **** of 0.3 mg l -1 (in desiccator) for particleboards was found to be equivalent to 0.04 mg m -3 in the European chamber test and 2.8 mg per 100 g in the perforator test. The variations in inter-laboratory tests are much larger than in intra-laboratory tests; the coefficient of variation is 16% and 6

  16. Modelisation et commande des redresseurs triphases fonctionnant a haut rendement et a faible taux de distorsion harmonique: Application au redresseur triphase de vienne

    NASA Astrophysics Data System (ADS)

    Belhadj Youssef, Nesrine

    Les problemes de la qualite de l'onde electrique constituent l'une des preoccupations majeures des fournisseurs de l'energie et des organismes specialises en qualite d'energie. Ce sujet a gagne davantage d'ampleur avec l'utilisation ascendante des convertisseurs de l'energie electrique dans la majorite des applications industrielles et domestiques. Dans le cadre de cette these, on s'interesse plus particulierement au type des convertisseurs alternatif/continu, dont le fonctionnement adequat implique la parfaite regulation du bus DC de tension, l'attenuation des harmoniques de courants, la compensation de l'energie reactive et la maximisation du rendement energetique. Ces differents criteres doivent etre maintenus pour diverses conditions de fonctionnement, c'est-a-dire independamment des variations parametriques auxquelles le systeme peut etre sujet. Il s'avere donc indispensable d'adopter des techniques de commande efficaces, ce qui passe par une modelisation correcte du convertisseur. L'optimisation du nombre de capteurs dans le circuit est egalement un facteur cle a prendre en consideration.

  17. Conceptual design study of concentrator enhanced solar arrays for space applications. 2kW Si and GaAs systems at 1 AU

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The effect of concentration level on the specific power for a deployable, thin, gallium arsenide cell array in geosynchronous orbit for 10 years in conjunction with a two dimensional flat plate trough concentrator (V trough) and also with a multiple flat plate concentrator was investigated as well as the effects for a conventional silicon cell array on a rigid substrate. For application to a thin GaAs array at 1 AU for 10 years, the V trough produces a 19% benefit in specific power and a dramatic reduction in array area, while the multiple flat plate collector design is not only of no benefit, but is a considerable detriment. The benefit it achieves by reducing array area is duplicated by the 2D design. For the silicon array on a rigid substrate, improvement in performance due to a concentrator with ordinary mirror coating is quite small: 9% increase in specific power, and 13% reduction in array area. When the concentrator mirrors are coated with an improved cold mirror coating, somewhat more significant results are obtained: 31% specific power improvement; and 27% area reduction. In both cases, a 10 year exposure reduces BOL output by 23%.

  18. Comparison of ozone and formaldehyde as poultry hatchery disinfectants

    SciTech Connect

    Whistler, P.E.; Sheldon, B.W. )

    1989-10-01

    Ozone and formaldehyde were compared as poultry hatchery disinfectants in a poultry setter, and evaluated for effectiveness. Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Proteus spp. were inoculated onto open petri plates and exposed to ozone or onto filter paper strips and exposed to ozone or formaldehyde in a poultry setter. Ozone (1.41 to 1.68% by weight) resulted in significant bacterial reductions of greater than 4 log10 on the open plates and greater than 3 log10 on filter paper strips, whereas formaldehyde (triple strength) resulted in greater than 7 log10 reduction on filter paper strips. Ozone was similarly lethal to organisms on filter paper strips at 90% relative humidity (RH) and 13.9 C, and at 50% RH and 37.7 C. Although under the conditions of this study formaldehyde (triple strength) was more lethal than ozone, ozone killed greater than 99.9% of the starting microbial populations. In the event that formaldehyde can no longer be used in the hatchery, an effective alternative may be ozone.

  19. Membrane-Associated Quinoprotein Formaldehyde Dehydrogenase from Methylococcus capsulatus Bath

    PubMed Central

    Zahn, James A.; Bergmann, David J.; Boyd, Jeffery M.; Kunz, Ryan C.; DiSpirito, Alan A.

    2001-01-01

    A membrane-associated, dye-linked formaldehyde dehydrogenase (DL-FalDH) was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The enzyme was the major formaldehyde-oxidizing enzyme in cells cultured in high (above 1 μmol of Cu per mg of cell protein) copper medium and expressing the membrane-associated methane monooxygenase. Soluble NAD(P)+-linked formaldehyde oxidation was the major activity in cells cultured in low-copper medium and expressing the soluble methane monooxygenase (Tate and Dalton, Microbiology 145:159–167, 1999; Vorholt et al., J. Bacteriol. 180:5351–5356, 1998). The membrane-associated enzyme is a homotetramer with a subunit molecular mass of 49,500 Da. UV-visible absorption, electron paramagnetic resonance, and electrospray mass spectrometry suggest the redox cofactor of the DL-FalDH is pyrroloquinoline quinone (PQQ), with a PQQ-to-subunit stochiometry of approximately 1:1. The enzyme was specific for formaldehyde, oxidizing formaldehyde to formate, and utilized the cytochrome b559/569 complex as the physiological electron acceptor. PMID:11698372

  20. Membrane-associated quinoprotein formaldehyde dehydrogenase from Methylococcus capsulatus Bath.

    PubMed

    Zahn, J A; Bergmann, D J; Boyd, J M; Kunz, R C; DiSpirito, A A

    2001-12-01

    A membrane-associated, dye-linked formaldehyde dehydrogenase (DL-FalDH) was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The enzyme was the major formaldehyde-oxidizing enzyme in cells cultured in high (above 1 micromol of Cu per mg of cell protein) copper medium and expressing the membrane-associated methane monooxygenase. Soluble NAD(P)(+)-linked formaldehyde oxidation was the major activity in cells cultured in low-copper medium and expressing the soluble methane monooxygenase (Tate and Dalton, Microbiology 145:159-167, 1999; Vorholt et al., J. Bacteriol. 180:5351-5356, 1998). The membrane-associated enzyme is a homotetramer with a subunit molecular mass of 49,500 Da. UV-visible absorption, electron paramagnetic resonance, and electrospray mass spectrometry suggest the redox cofactor of the DL-FalDH is pyrroloquinoline quinone (PQQ), with a PQQ-to-subunit stochiometry of approximately 1:1. The enzyme was specific for formaldehyde, oxidizing formaldehyde to formate, and utilized the cytochrome b(559/569) complex as the physiological electron acceptor. PMID:11698372

  1. Formaldehyde as a basis for residential ventilation rates

    SciTech Connect

    Sherman, M.H.; Hodgson, A.T.

    2002-04-28

    Traditionally, houses in the U.S. have been ventilated by passive infiltration in combination with active window opening. However in recent years, the construction quality of residential building envelopes has been improved to reduce infiltration, and the use of windows for ventilation also may have decreased due to a number of factors. Thus, there has been increased interest in engineered ventilation systems for residences. The amount of ventilation provided by an engineered system should be set to protect occupants from unhealthy or objectionable exposures to indoor pollutants, while minimizing energy costs for conditioning incoming air. Determining the correct ventilation rate is a complex task, as there are numerous pollutants of potential concern, each having poorly characterized emission rates, and poorly defined acceptable levels of exposure. One ubiquitous pollutant in residences is formaldehyde. The sources of formaldehyde in new houses are reasonably understood, and there is a large body of literature on human health effects. This report examines the use of formaldehyde as a means of determining ventilation rates and uses existing data on emission rates of formaldehyde in new houses to derive recommended levels. Based on current, widely accepted concentration guidelines for formaldehyde, the minimum and guideline ventilation rates for most new houses are 0.28 and 0.5 air changes per hour, respectively.

  2. [Disinfection and sterilization of thermolabile instruments with gaseous formaldehyde].

    PubMed

    Mecke, P

    1984-12-01

    For several years formaldehyde-gas-underpressure procedures are increasingly used for disinfection and sterilization of medical thermolabile instruments. In many places, however, uncertainty and sceptism, if these methods are sufficient in the medical field, are existing. This is understandable, since no generally test instructions are available. The principal suitability of gaseous formaldehyde for disinfection and sterilization, however, had been demonstrated by several investigators. Precondition for reliable efficacy during routine use is an apparatus which is equipped with feed-back techniques and which guarantees the bactericidal and fungicidal activity required for medical use. Decontamination procedures on the basis of gaseous formaldehyde under normal conditions of temperature and pressure must be regarded as unsafe. St. faecalis and the spores of B. stearothermophilus showed the highest formaldehyde resistance within the group of common biological testorganisms. In order to test the efficacy of corresponding procedures testorganisms have to be placed into testdevices with small lumina. The penetration of these devices to formaldehyde and vapour should be similar to that of the longest instruments with the smallest lumina, which are intended to be decontaminated by the testprocedure. PMID:6442506

  3. Comparison of ozone and formaldehyde as poultry hatchery disinfectants.

    PubMed

    Whistler, P E; Sheldon, B W

    1989-10-01

    Ozone and formaldehyde were compared as poultry hatchery disinfectants in a poultry setter, and evaluated for effectiveness. Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Proteus spp. were inoculated onto open petri plates and exposed to ozone or onto filter paper strips and exposed to ozone or formaldehyde in a poultry setter. Ozone (1.41 to 1.68% by weight) resulted in significant bacterial reductions of greater than 4 log10 on the open plates and greater than 3 log10 on filter paper strips, whereas formaldehyde (triple strength) resulted in greater than 7 log10 reduction on filter paper strips. Ozone was similarly lethal to organisms on filter paper strips at 90% relative humidity (RH) and 13.9 C, and at 50% RH and 37.7 C. Although under the conditions of this study formaldehyde (triple strength) was more lethal than ozone, ozone killed greater than 99.9% of the starting microbial populations. In the event that formaldehyde can no longer be used in the hatchery, an effective alternative may be ozone. PMID:2511564

  4. High performance Au/PZT/TiOxNy/Si MFIS structure for next generation ferroelectric memory applications

    NASA Astrophysics Data System (ADS)

    Sharma, Deepak K.; Khosla, Robin; Sharma, Satinder K.

    2015-05-01

    The Metal-Ferroelectric-Insulator-Semiconductor (MFIS) capacitors with thin 20 nm lead zirconate titanate (PZT) and titanium oxynitride (TiOxNy) buffer layer were fabricated by RF magnetron sputtering technique and characterized. TiOxNy as a buffer layer deposited for the first time for MFIS application at different thicknesses and fabricated structure was found to exhibit excellent electrical characteristics at 14 nm TiOxNy. Memory window of 0.4 V was found at low sweep voltage of ± 3 V which increases to 1.8 V at sweep voltage of ±14 V indicating multilevel data storage. Moreover the fabricated structure possesses low leakage current density of ˜4 µA/cm2 at 36 nm TiOxNy which increases to 12 µA/cm2 at 4 nm TiOxNy at 5 V, reasonable limit. Furthermore, the fabricated structure possesses outstanding data retention capability at 14 nm TiOxNy; the high and low capacitance becomes constant after few seconds and clearly distinguishable for 1h and 30 min. This shows that proposed MFIS structure is suitable for high performance ferroelectric memory applications.

  5. Facile synthesis and intraparticle self-catalytic oxidation of dextran-coated hollow Au-Ag nanoshell and its application for chemo-thermotherapy.

    PubMed

    Jang, Hongje; Kim, Young-Kwan; Huh, Hyun; Min, Dal-Hee

    2014-01-28

    Galvanic replacement reaction is a useful method to prepare various hollow nanostructures. We developed fast and facile preparation of biocompatible and structurally robust hollow Au-Ag nanostructures by using dextran-coated Ag nanoparticles. Oxidation of the surface dextran alcohols was enabled by catalytic activity of the core Au-Ag nanostructure, introducing carbonyl groups that are useful for further bioconjugation. Subsequent doxorubicin (Dox) conjugation via Schiff base formation was achieved, giving high payload of approximately 35 000 Dox per particle. Near-infrared-mediated photothermal conversion showed high efficacy of the Dox-loaded Au-Ag nanoshell as a combinational chemo-thermotherapy to treat cancer cells. PMID:24383549

  6. Preparation of Au Nanoparticles Immobilized Cross-Linked Poly(4-vinylpyridine) Nanofibers and Their Catalytic Application for the Reduction of 4-Nitrophenol.

    PubMed

    Qin, Qi-Hu; Na, Hui; Zhang, Chunyu; Yu, Qizhou; Zhang, Xue-Quan; Zhang, He-Xin

    2015-05-01

    Catalytic nanofibers are prepared by the immobilization of Au nanoparticles (AuNPs) onto the surface of cross-linked electrospun poly(4-vinylpyridine) (P4VP) nanofibers. The crosslinking of the P4VP nanofibers by 1,4-diiodobutane via quaternization reaction greatly enhances the stability of the nanofibers against the solvent dissolution, which can then be used as promising platform for the immobilization of catalytic metal nanoparticles. The AuNPs immobilized cross-linked P4VP nanofibers have shown a good catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). PMID:26505022

  7. FORMALDEHYDE GAS INACTIVATION OF BACILLUS ANTHRACIS, BACILLUS SUBTILIS AND GEOBACILLUS STEAROTHERMOPHILUS SPORES ON INDOOR SURFACE MATERIALS.

    EPA Science Inventory

    Research evaluated the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface material using formaldehyde gas. Spores were dried on seven types of indoor surfaces and exposed to 1100 ppm formaldehyde gas for 10 hr. Fo...

  8. Systematic review of the epidemiology literature on formaldehyde and cancers of the upper respiratory tract

    EPA Science Inventory

    Background: EPA is currently drafting a Toxicological Review of formaldehyde. As part of the comprehensive evaluation of potential hazards associated with exposure to formaldehyde, the potential hazards for cancers of the upper respiratory tract are being evaluated. We are aware ...

  9. Systematic review of the epidemiology literature on formaldehyde and lymphohematopoietic cancers

    EPA Science Inventory

    Background: EPA is currently drafting a Toxicological Review of formaldehyde. As part of the comprehensive evaluation of potential hazards associated with exposure to formaldehyde, the potential hazards for lymphohematopoietic cancers are being evaluated. We are aware of multiple...

  10. 24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...-to-urea ratio is increased; (B) The amount of formaldehyde resin used is increased; or (C) The press... formaldehyde-to-urea ratio is increased; or (ii) In the case of particleboard or plywood, the finishing or...

  11. 24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...-to-urea ratio is increased; (B) The amount of formaldehyde resin used is increased; or (C) The press... formaldehyde-to-urea ratio is increased; or (ii) In the case of particleboard or plywood, the finishing or...

  12. 24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...-to-urea ratio is increased; (B) The amount of formaldehyde resin used is increased; or (C) The press... formaldehyde-to-urea ratio is increased; or (ii) In the case of particleboard or plywood, the finishing or...

  13. Amended safety assessment of formaldehyde and methylene glycol as used in cosmetics.

    PubMed

    Boyer, Ivan J; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2013-01-01

    Formaldehyde and methylene glycol may be used safely in cosmetics if established limits are not exceeded and are safe for use in nail hardeners in the present practices of use and concentration, which include instructions to avoid skin contact. In hair-smoothing products, however, in the present practices of use and concentration, formaldehyde and methylene glycol are unsafe. Methylene glycol is continuously converted to formaldehyde, and vice versa, even at equilibrium, which can be easily shifted by heating, drying, and other conditions to increase the amount of formaldehyde. This rapid, reversible formaldehyde/methylene glycol equilibrium is distinguished from the slow, irreversible release of formaldehyde resulting from the so-called formaldehyde releaser preservatives, which are not addressed in this safety assessment (formaldehyde releasers may continue to be safely used in cosmetics at the levels established in their individual Cosmetic Ingredient Review safety assessments). PMID:24335968

  14. Formaldehyde and hydroperoxides at Mauna Loa Observatory

    SciTech Connect

    Heikes, B.G. )

    1992-11-20

    Hydrogen peroxide, formaldehyde, and a measure of organic hydroperoxides are presented from the Mauna Loa Observatory Photochemistry Experiment (MLOPEX). MLOPEX was conducted from May 1 to June 4, 1988, at the Mauna Loa Observatory on the island of Hawaii. A modified dual-enzyme serial-coil H[sub 2]O[sub 2]/ROOH method was used to quantify these species. A second enzyme method was used to measure CH[sub 2]O. The location and meteorology at the Mauna Loa Observatory site permitted 35 days of measurements to be made in free tropospheric air and in modified marine boundary layer air. Average concentrations of H[sub 2]O[sub 2], ROOH, and CH[sub 2]O were 1050, 140, and 100 pptv in free tropospheric, or down-slope air. In upslope air, or modified marine boundary layer air, average concentrations were 900, 150, and 190 pptv. Maximum concentrations for all three species were experienced during a two day photochemical haze episode and were 3230, 440, and 450 pptv for H[sub 2]O[sub 2], ROOH, and CH[sub 2]O. H[sub 2]O[sub 2] was depleted in air which had recently been processed by cloud or precipitation. The measured concentrations of these three species were comparable to prior measurements in well- aged air, but were lower than previous models have predicted. Part of this discrepancy may be due to the treatment of heterogeneous removal processes, dry and wet deposition, in these models. The measured ratio of ROOH to H[sub 2]O[sub 2] is significantly different than present theory predicts, with ROOH as measured being approximately a factor of 5 too low. 61 refs., 13 figs., 2 tabs.

  15. Health effects of low-level exposure to formaldehyde

    SciTech Connect

    Main, D.M.; Hogan, T.J.

    1983-12-01

    Twenty-one subjects exposed to formaldehyde (at levels between 0.12 and 1.6 parts per million (ppm)) in two mobile trailers and the remaining 18 unexposed workers of the same workforce were examined by questionnaire and spirometry. Symptoms of eye and throat irritation and increased headache and fatigue were significantly more common among the exposed group than the comparison group. Irritation of the nose, chest tightness, and shortness of breath were also more common among the exposed. Spirometry revealed no decrease in ventilatory function among the exposed workers. The significant increase in frequency of individuals with symptoms indicated an adverse health effect from exposure to formaldehyde at levels between 0.12 and 1.6 ppm. This may have implications regarding the adequacy of the US permissable exposure limit value and suggest the need for further examination of the health effects of formaldehyde in the nonoccupational environment.

  16. Formaldehyde Concentration Dynamics of the International Space Station Cabin Atmosphere

    NASA Technical Reports Server (NTRS)

    Perry, J. L.

    2005-01-01

    Formaldehyde presents a significant challenge to maintaining cabin air quality on board crewed spacecraft. Generation sources include offgassing from a variety of non-metallic materials as well as human metabolism. Because generation sources are pervasive and human health can be affected by continual exposure to low concentrations, toxicology and air quality control engineering experts jointly identified formaldehyde as a key compound to be monitored as part the International Space Station's (ISS) environmental health monitoring and maintenance program. Data acquired from in-flight air quality monitoring methods are the basis for assessing the cabin environment's suitability for long-term habitation and monitoring the performance of passive and active controls that are in place to minimize crew exposure. Formaldehyde concentration trends and dynamics served in the ISS cabin atmosphere are reviewed implications to present and future flight operations discussed.

  17. Evaluation of a low-temperature steam and formaldehyde sterilizer.

    PubMed

    Kanemitsu, K; Kunishima, H; Imasaka, T; Ishikawa, S; Harigae, H; Yamato, S; Hirayama, Y; Kaku, M

    2003-09-01

    We evaluated a low-temperature steam and formaldehyde (LTSF) sterilizer based on the draft European Standard prEN 14180. Microbiological tests were conducted on small and full loads using process challenge devices in five programs (P1-P5). With small loads all tests showed no growth of Bacillus stearothermophilus (ATCC7953) spores. However, positive cultures were observed with full-load tests using P5 (sterilization temperature, 50 degrees C). Our data indicated that the load influenced the efficacy of the LTSF sterilizer. Desorption tests were conducted to determine residual formaldehyde in indicator strips. The mean concentrations of formaldehyde in P1-P5 were 31.9, 56.3, 54.9, 82.2 and 180.6 microg, respectively, which are below the limits allowed by the draft Standard. Our results indicate that the LTSF sterilizer is useful for sterilization because of its excellent efficacy, short handling time, and safety. PMID:14505609

  18. Formaldehyde--study of indoor air pollution in Austria.

    PubMed

    Koeck, M; Pichler-Semmelrock, F P; Schlacher, R

    1997-09-01

    As part of a long-term study of indoor air pollution, formaldehyde concentrations were determined in 792 apartments following complaints by inhabitants. Measurements were carried out using Draeger tubes as well as the acetyl acetone method. In 157 apartments, HCHO concentrations of more than 0.1 ppm, exceeding the recommended standard values for indoor air concentrations, were determined. The concentrations determined tended to decrease over time. As far as they were caused by furnishings, they were limited to the spaces where these furnishings were installed. In older-style prefabricated houses with foam-filled particle-board wall systems, concentrations of more than 1.0 ppm were determined. In spite of legal regulations governing the release of formaldehyde from substances, preparations and products containing formaldehyde which have been in existence in Austria since 1990, this substance must still be considered as a possible factor of indoor pollution in causing feelings of ill-health. PMID:9386898

  19. Ultra-relativistic Au+Au and d+Au collisions:

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Hauer, M.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Seals, H.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    In this talk I will review PHOBOS data on charged particle multiplicities, obtained in Au+Au and d+Au collisions at RHIC. The general features of the Au+Au pseudorapidity distributions results will be discussed and compared to those of /line{p}p collisions. The total charged particle multiplicity, scaled by the number of participant pairs, is observed to be about 40% higher in Au+Au collisions than in /line{p}p and d+Au systems, but, surprisingly at the same level of e+e- collisions. Limiting fragmentation scaling is seen to be obeyed in Au+Au collisions.

  20. An ultra-fast illuminating fluorescent probe for monitoring formaldehyde in living cells, shiitake mushrooms, and indoors.

    PubMed

    He, Longwei; Yang, Xueling; Ren, Mingguang; Kong, Xiuqi; Liu, Yong; Lin, Weiying

    2016-07-21

    An ultra-fast illuminating fluorescent formaldehyde (FA) probe (R6-FA) was designed and synthesized, and it exhibited a significant response to both FA in aqueous solution and as a gas. We have employed R6-FA not only to image FA in living cells, but also to detect FA in dried shiitake mushrooms and indoors for the first time, indicating its broad potential applications for monitoring FA in living systems, the food industry, and the environment. PMID:27398723

  1. Reproductive and Developmental Toxicity of Formaldehyde: A Systematic Review

    PubMed Central

    Duong, Anh; Steinmaus, Craig; McHale, Cliona M.; Vaughan, Charles P.; Zhang, Luoping

    2011-01-01

    Formaldehyde, the recently classified carcinogen and ubiquitous environmental contaminant, has long been suspected of causing adverse reproductive and developmental effects, but previous reviews were inconclusive, due in part, to limitations in the design of many of the human population studies. In the current review, we systematically evaluated evidence of an association between formaldehyde exposure and adverse reproductive and developmental effects, in human populations and in vivo animal studies, in the peer-reviewed literature. The mostly retrospective human studies provided evidence of an association of maternal exposure with adverse reproductive and developmental effects. Further assessment of this association by meta-analysis revealed an increased risk of spontaneous abortion (1.76, 95% CI 1.20–2.59, p=0.002) and of all adverse pregnancy outcomes combined (1.54, 95% CI 1.27–1.88, p<0.001), in formaldehyde-exposed women, although differential recall, selection bias, or confounding cannot be ruled out. Evaluation of the animal studies including all routes of exposure, doses and dosing regimens studied, suggested positive associations between formaldehyde exposure and reproductive toxicity, mostly in males. Potential mechanisms underlying formaldehyde-induced reproductive and developmental toxicities, including chromosome and DNA damage (genotoxicity), oxidative stress, altered level and/or function of enzymes, hormones and proteins, apoptosis, toxicogenomic and epigenomic effects (such as DNA methylation), were identified. To clarify these associations, well-designed molecular epidemiologic studies, that include quantitative exposure assessment and diminish confounding factors, should examine both reproductive and developmental outcomes associated with exposure in males and females. Together with mechanistic and animal studies, this will allow us to better understand the systemic effect of formaldehyde exposure. PMID:21787879

  2. Safety in the Chemical Laboratory: Atmospheric Formaldehyde Levels in an Academic Laboratory.

    ERIC Educational Resources Information Center

    Clausz, John C.; And Others

    1984-01-01

    Determined whether improved ventilation and use of "formaldehyde-free" biological specimens could reduce the levels of formaldehyde in air to which students and faculty would be exposed. Both methods were found to be effective in reducing formaldehyde levels in air. (JN)

  3. 21 CFR 177.1460 - Melamine-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Melamine-formaldehyde resins in molded articles... Repeated Use Food Contact Surfaces § 177.1460 Melamine-formaldehyde resins in molded articles. Melamine-formaldehyde resins may be safely used as the food-contact surface of molded articles intended for use...

  4. 40 CFR 721.9480 - Resorcinol, formaldehyde substituted carbomonocycle resin (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Resorcinol, formaldehyde substituted... New Uses for Specific Chemical Substances § 721.9480 Resorcinol, formaldehyde substituted... as resorcinol, formaldehyde substituted carbomonocycle resin (PMN P-89-769) is subject to...

  5. 40 CFR 721.7220 - Polymer of substituted phenol, formaldehyde, epichlorohydrin, and disubstituted benzene.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., formaldehyde, epichlorohydrin, and disubstituted benzene. 721.7220 Section 721.7220 Protection of Environment..., formaldehyde, epichlorohydrin, and disubstituted benzene. (a) Chemical substance and significant new uses..., formaldehyde, epichlorohydrin, and disubstituted benzene (PMN P-89-1104) is subject to reporting under...

  6. 40 CFR 721.7220 - Polymer of substituted phenol, formaldehyde, epichlorohydrin, and disubstituted benzene.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., formaldehyde, epichlorohydrin, and disubstituted benzene. 721.7220 Section 721.7220 Protection of Environment..., formaldehyde, epichlorohydrin, and disubstituted benzene. (a) Chemical substance and significant new uses..., formaldehyde, epichlorohydrin, and disubstituted benzene (PMN P-89-1104) is subject to reporting under...

  7. 40 CFR 721.7220 - Polymer of substituted phenol, formaldehyde, epichlorohydrin, and disubstituted benzene.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., formaldehyde, epichlorohydrin, and disubstituted benzene. 721.7220 Section 721.7220 Protection of Environment..., formaldehyde, epichlorohydrin, and disubstituted benzene. (a) Chemical substance and significant new uses..., formaldehyde, epichlorohydrin, and disubstituted benzene (PMN P-89-1104) is subject to reporting under...

  8. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Formaldehyde, reaction products with...

  9. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Formaldehyde, reaction products with...

  10. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, reaction products with...

  11. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, reaction products with...

  12. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Formaldehyde, reaction products with...

  13. Formaldehyde: Industrial health hazards. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning the health hazards of formaldehyde inhalation. Health hazard evaluation reports of industrial sites are discussed, and the effects of formaldehyde on animals and humans are considered. Industrial hygiene sampling method and analytical methods to quantitate formaldehyde are also discussed. (Contains a minimum of 159 citations and includes a subject term index and title list.)

  14. Formaldehyde: Industrial health hazards. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1996-03-01

    The bibliography contains citations concerning the health hazards of formaldehyde inhalation. Health hazard evaluation reports of industrial sites are discussed, and the effects of formaldehyde on animals and humans are considered. Industrial hygiene sampling method and analytical methods to quantitate formaldehyde are also discussed. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  15. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Amine-modified urea-formaldehyde... Specific Chemical Substances § 721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical... as amine-modified urea-formaldehyde polymer (PMN P-12-182) is subject to reporting under this...

  16. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Urea-formaldehyde resins in molded articles. 177... Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea... section, urea-formaldehyde resins are those produced when 1 mole of urea is made to react with not...

  17. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  18. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  19. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Amine-modified urea-formaldehyde... Specific Chemical Substances § 721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical... as amine-modified urea-formaldehyde polymer (PMN P-12-182) is subject to reporting under this...

  20. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  1. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  2. 40 CFR 721.7046 - Formaldehyde, polymer with substituted phenols, glycidyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymer with substituted... New Uses for Specific Chemical Substances § 721.7046 Formaldehyde, polymer with substituted phenols... substance identified as formaldehyde, polymer with substituted phenols, glycidyl ether (PMN P-93-955)...

  3. 40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymers with... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject...

  4. 40 CFR 721.3807 - Formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymer with phenol and... Significant New Uses for Specific Chemical Substances § 721.3807 Formaldehyde, polymer with phenol and 1,2,3... chemical substance identified as formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated...

  5. 40 CFR 721.10232 - N-arylamino-phenol-formaldehyde condensate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false N-arylamino-phenol-formaldehyde... Specific Chemical Substances § 721.10232 N-arylamino-phenol-formaldehyde condensate (generic). (a) Chemical... as n-arylamino-phenol-formaldehyde condensate (PMN P-08-694) is subject to reporting under...

  6. 40 CFR 721.3807 - Formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Formaldehyde, polymer with phenol and... Significant New Uses for Specific Chemical Substances § 721.3807 Formaldehyde, polymer with phenol and 1,2,3... chemical substance identified as formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated...

  7. 40 CFR 721.3807 - Formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Formaldehyde, polymer with phenol and... Significant New Uses for Specific Chemical Substances § 721.3807 Formaldehyde, polymer with phenol and 1,2,3... chemical substance identified as formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated...

  8. 40 CFR 721.10232 - N-arylamino-phenol-formaldehyde condensate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false N-arylamino-phenol-formaldehyde... Specific Chemical Substances § 721.10232 N-arylamino-phenol-formaldehyde condensate (generic). (a) Chemical... as n-arylamino-phenol-formaldehyde condensate (PMN P-08-694) is subject to reporting under...

  9. 40 CFR 721.3812 - Substituted phenols and formaldehyde polymer, alkylated (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Substituted phenols and formaldehyde... New Uses for Specific Chemical Substances § 721.3812 Substituted phenols and formaldehyde polymer... substance identified generically as substituted phenols and formaldehyde polymer, alkylated (PMN...

  10. 40 CFR 721.10232 - N-arylamino-phenol-formaldehyde condensate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false N-arylamino-phenol-formaldehyde... Specific Chemical Substances § 721.10232 N-arylamino-phenol-formaldehyde condensate (generic). (a) Chemical... as n-arylamino-phenol-formaldehyde condensate (PMN P-08-694) is subject to reporting under...

  11. 40 CFR 721.3807 - Formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Formaldehyde, polymer with phenol and... Significant New Uses for Specific Chemical Substances § 721.3807 Formaldehyde, polymer with phenol and 1,2,3... chemical substance identified as formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated...

  12. 40 CFR 721.3812 - Substituted phenols and formaldehyde polymer, alkylated (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Substituted phenols and formaldehyde... New Uses for Specific Chemical Substances § 721.3812 Substituted phenols and formaldehyde polymer... substance identified generically as substituted phenols and formaldehyde polymer, alkylated (PMN...

  13. 40 CFR 721.3812 - Substituted phenols and formaldehyde polymer, alkylated (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Substituted phenols and formaldehyde... New Uses for Specific Chemical Substances § 721.3812 Substituted phenols and formaldehyde polymer... substance identified generically as substituted phenols and formaldehyde polymer, alkylated (PMN...

  14. 40 CFR 721.3807 - Formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymer with phenol and... Significant New Uses for Specific Chemical Substances § 721.3807 Formaldehyde, polymer with phenol and 1,2,3... chemical substance identified as formaldehyde, polymer with phenol and 1,2,3-propanetriol, methylated...

  15. 40 CFR 721.7046 - Formaldehyde, polymer with substituted phenols, glycidyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymer with substituted... New Uses for Specific Chemical Substances § 721.7046 Formaldehyde, polymer with substituted phenols... substance identified as formaldehyde, polymer with substituted phenols, glycidyl ether (PMN P-93-955)...

  16. 40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymers with... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject...

  17. Β-cyclodextrin polymer as a linker to fabricate ternary nanocomposites AuNPs/pATP-β-CDP/rGO and their electrochemical application.

    PubMed

    Chen, Ming; Shen, Xiao; Liu, Peipei; Wei, Ying; Meng, Yang; Zheng, Gang; Diao, Guowang

    2015-03-30

    Based on the self-assembly strategy, β-cyclodextrin polymer (β-CDP) was used as a linker to connect reduced graphene oxide (rGO) and p-aminothiophenol (pATP). Then, pre-prepared gold nanoparticles (AuNPs) can self-assemble onto the surface of pATP-β-CDP/rGO to obtain new ternary nanocomposites AuNPs/pATP-β-CDP/rGO. The amount or the density of AuNPs can be adjusted by changing the concentration of pATP. UV-vis and (1)H NMR spectra confirmed the formation of inclusion complex between pATP and β-CDP. β-CDP might improve the dispersity of rGO in aqueous and the surface property of rGO. AuNPs/pATP-β-CDP/rGO modified electrode displayed high electrochemical response toward a pesticide-imidacloprid (IDP). The enrichment capability and molecular recognition of β-CDP and the catalytic property of AuNPs for IDP molecules synergistically promoted the electrochemical response of rGO modified electrode. Additionally, ternary nanocomposites exhibited the good electrocatalytic performance for oxygen reduction in O2-saturated 0.1M H2SO4 solution. The proposed synthesis strategy provided a facile, feasible and effective method for development of electrochemical sensors and Au-based catalysts for fuel cells. PMID:25563941

  18. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    NASA Astrophysics Data System (ADS)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-03-01

    Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min-1 and turnover frequency is 5457 h-1.

  19. A study on the effect of low energy ion beam irradiation on Au/TiO2 system for its application in photoelectrochemical splitting of water

    NASA Astrophysics Data System (ADS)

    Verma, Anuradha; Srivastav, Anupam; Sharma, Dipika; Banerjee, Anamika; Sharma, Shailja; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab

    2016-07-01

    Nanostructured TiO2 thin films were deposited on indium tin oxide (ITO) substrate via sol-gel technique and were modified by plasmonic Au layer. The plasmonic Au modified TiO2 (Au/TiO2) thin films were then irradiated with 500 keV Ar2+ ion beam at different ion fluences viz. 1 × 1016, 3 × 1016 and 1 × 1017 to study the effect of nuclear energy deposition on the morphology, crystallinity, band gap, surface plasmon resonance (SPR) peak exhibited by Au particles and photoelectrochemical properties of the system. Prepared thin films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS) measurements and UV-visible spectroscopy. The photoelectrochemical measurements revealed that both Au/TiO2 and Au/TiO2 thin film irradiated at 1 × 1016 fluence exhibits enhanced photoelectrochemical response in comparison to pristine TiO2. The film irradiated at 1 × 1016 fluence offered maximum applied bias photon-to-current efficiency (ABPE) and shows 6 times increment in photocurrent density which was attributed to more negative flat band potential, maximum decrease in band gap, high open circuit voltage (Voc) and reduced charge transfer resistance.

  20. Synthesis and Thermal Degradation Studies of Melamine Formaldehyde Resins

    PubMed Central

    Ullah, Sami; Bustam, M. A.; Nadeem, M.; Tan, W. L.; Shariff, A. M.

    2014-01-01

    Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10. PMID:25436237

  1. Chemical and physical basics of routine formaldehyde fixation

    PubMed Central

    Thavarajah, Rooban; Mudimbaimannar, Vidya Kazhiyur; Elizabeth, Joshua; Rao, Umadevi Krishnamohan; Ranganathan, Kannan

    2012-01-01

    Formaldehyde is the widely employed fixative that has been studied for decades. The chemistry of fixation has been studied widely since the early 20th century. However, very few studies have been focused on the actual physics/chemistry aspect of process of this fixation. This article attempts to explain the chemistry of formaldehyde fixation and also to study the physical aspects involved in the fixation. The factors involved in the fixation process are discussed using well documented mathematical and physical formulae. The deeper understanding of these factors will enable pathologist to optimize the factors and use them in their favor. PMID:23248474

  2. Chemical and physical basics of routine formaldehyde fixation.

    PubMed

    Thavarajah, Rooban; Mudimbaimannar, Vidya Kazhiyur; Elizabeth, Joshua; Rao, Umadevi Krishnamohan; Ranganathan, Kannan

    2012-09-01

    Formaldehyde is the widely employed fixative that has been studied for decades. The chemistry of fixation has been studied widely since the early 20(th) century. However, very few studies have been focused on the actual physics/chemistry aspect of process of this fixation. This article attempts to explain the chemistry of formaldehyde fixation and also to study the physical aspects involved in the fixation. The factors involved in the fixation process are discussed using well documented mathematical and physical formulae. The deeper understanding of these factors will enable pathologist to optimize the factors and use them in their favor. PMID:23248474

  3. Some effects of formaldehyde on the upper respiratory tract

    SciTech Connect

    Ballenger, J.J.

    1984-11-01

    Being highly soluble in water gaseous formaldehyde (HCHO) is virtually completely removed by the nose during nasal respiration so that nasal disease may follow. This report is a review of pertinent information that is known about the effect of formaldehyde on the nose both in animals and humans. It is evident from the literature that rats develop nasal carcinoma at ambient levels of HCHO occasionally encountered by humans and it is hoped that this report will elucidate the possible threat HCHO presents to humans.

  4. Synthesis and thermal degradation studies of melamine formaldehyde resins.

    PubMed

    Ullah, Sami; Bustam, M A; Nadeem, M; Naz, M Y; Tan, W L; Shariff, A M

    2014-01-01

    Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10. PMID:25436237

  5. A survey of formaldehyde in high Galactic latitudes

    NASA Technical Reports Server (NTRS)

    Heithausen, A.; Mebold, U.; De Vries, H. W.

    1987-01-01

    The discovery of formaldehyde (H2CO) in four out of 15 CO-clouds observed in high Galactic latitudes is reported. For one of these a velocity-integrated formaldehyde map is presented. The clouds are clearly connected to CO clouds described by de Vries et al. (1986), to Lynds bright and dark nebulae (Lynds, 1963), and to the Galactic infrared cirrus (Low et al., 1984). The distribution of CO and H2CO clouds is compared. The depths of the l(10-11)H2CO lines show no correlation to the integrated J = l-0(C-12)O line intensities.

  6. Immobilized formaldehyde-metabolizing enzymes from Hansenula polymorpha for removal and control of airborne formaldehyde.

    PubMed

    Sigawi, Sasi; Smutok, Oleh; Demkiv, Olha; Zakalska, Oksana; Gayda, Galina; Nitzan, Yeshayahu; Nisnevitch, Marina; Gonchar, Mykhaylo

    2011-05-20

    Formaldehyde (FA)-containing indoor air has a negative effect on human health and should be removed by intensive ventilation or by catalytic conversion to non-toxic products. FA can be oxidized by alcohol oxidase (AOX) taking part in methanol metabolism of methylotrophic yeasts. In the present work, AOX isolated from a Hansenula polymorpha C-105 mutant (gcr1 catX) overproducing this enzyme in glucose medium, was tested for its ability to oxidize airborne FA. A continuous fluidized bed bioreactor (FBBR) was designed to enable an effective bioconversion of airborne FA by AOX or by permeabilized mutant H. polymorpha C-105 cells immobilized in calcium alginate beads. The immobilized AOX having a specific activity of 6-8 U mg⁻¹ protein was shown to preserve 85-90% of the initial activity. The catalytic parameters of the immobilized enzyme were practically the same as for the free enzyme (k(cat)/K(m) was 2.35×10³ M⁻¹ s⁻¹ vs 2.89×10³ M⁻¹ s⁻¹, respectively). The results showed that upon bubbling of air containing from 0.3 up to 18.5 ppm FA through immobilized AOX in the range of 1.3-26.6 U g⁻¹ of the gel resulted in essential decrease of FA concentration in the outlet gas phase (less than 0.02-0.03 ppm, i.e. 10-fold less than the threshold limit value). It was also demonstrated that a FBBR with immobilized permeabilized C-105 cells provided more than 90% elimination of airborne FA. The process was monitored by a specially constructed enzymatic amperometric biosensor based on FA oxidation by NAD+ and glutathione-dependent formaldehyde dehydrogenase from the recombinant H. polymorpha Tf 11-6 strain. PMID:21504769

  7. Structural, electronic and magnetic properties of Au-based monolayer derivatives in honeycomb structure

    NASA Astrophysics Data System (ADS)

    Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We present electronic properties of atomic layer of Au, Au2-N, Au2-O and Au2-F in graphene-like structure within the framework of density functional theory (DFT). The lattice constant of derived monolayers are found to be higher than the pristine Au monolayer. Au monolayer is metallic in nature with quantum ballistic conductance calculated as 4G0. Similarly, Au2-N and Au2-F monolayers show 4G0 and 2G0 quantum conductance respectively while semiconducting nature with calculated band gap of 0.28 eV has been observed for Au2-O monolayer. Most interestingly, half metalicity has been predicted for Au2-N and Au2-F monolayers. Our findings may have importance for the application of these monolayers in nanoelectronic and spintronics.

  8. Au@Ag Heterogeneous Nanorods as Nanozyme Interfaces with Peroxidase-Like Activity and Their Application for One-Pot Analysis of Glucose at Nearly Neutral pH.

    PubMed

    Han, Lei; Li, Cuncheng; Zhang, Tao; Lang, Qiaolin; Liu, Aihua

    2015-07-01

    As substitutes for natural peroxidases, most nanomaterial-based enzyme mimetics (nanozymes) have unique properties such as high stability, low-cost, large surface area, and high catalytic activity. However, they usually work in acidic conditions and thus impede their real applications. In this work, by modulating the nanostructure, composition, and surface property of the bimetallic materials, the positively charged poly(diallyldimethylammonium)-stabilized Au@Ag heterogeneous nanorods (NRs) were developed as synergistic peroxidase-like interfaces, which exhibited high activity over a wide pH range (pH 4.0-6.5) using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the chromogenic substrate. At pH 6.5, the peroxidase-like activity for the Au@Ag heterogeneous NRs was stable and optimal within 20-40 °C. Moreover, the Au@Ag heterogeneous NRs showed excellent temperature stability and long-term storage stability. Given these characters, the detection of H2O2 at pH 6.5 was proposed on the basis of the Au@Ag heterogeneous NRs catalyzing the colorimetric reaction of H2O2 and ABTS, where the oxidized ABTS showed a typical absorption peak at 414 nm. The absorbance at 414 nm was linear with H2O2 concentration from 0.01 to 10 mM. Further, considering that Au@Ag heterogeneous NRs and glucose oxidase (GOx) have similar optimal pH for catalytic activities, a novel one-pot method for the detection of glucose was developed by the coupled catalytic reaction using GOx, Au@Ag heterogeneous NRs, and ABTS at nearly neutral pH (pH 6.5) and 37 °C. This proposed method had simple and rapid processes, wide linear range (0.05-20 mM), and reliability for the successful analysis of real samples. On the basis of these attractive and unique characteristics, Au@Ag heterogeneous NRs can become promising substitutes for peroxidase in analytical chemistry and environmental science. PMID:26076372

  9. Allergic contact dermatitis from formaldehyde textile resins in surgical uniforms and nonwoven textile masks.

    PubMed

    Donovan, Jeff; Skotnicki-Grant, Sandy

    2007-03-01

    Despite a trend for reduction in the concentration of free formaldehyde in textiles, formaldehyde textile resin (FTR) allergic contact dermatitis (ACD) remains an important clinical issue and is likely underdiagnosed. Patients with FTR ACD may react to formaldehyde released from the resin or to the resin itself. Screening with formaldehyde and ethyleneurea/melamine formaldehyde resin will uncover most cases. Patch testing with the suspected offending fabric most often leads to false-negative results. We present a case of a 49-year-old pediatrician who developed a severe widespread dermatitis caused by contact with FTRs from her hospital "greens" ("scrubs") and mask. PMID:17303043

  10. Using high-temperature formaldehyde sterilization as a model for studying gaseous sterilization.

    PubMed

    Mosley, Gregg A

    2008-01-01

    This study uses the high-temperature formaldehyde sterilization system provided by the Harvey Chemiclave, manufactured by Barnstead Thermolyne Corporation (Dubuque, IA), as a model to investigate certain phenomena associated with gaseous chemical sterilization systems. Although formaldehyde sterilization presents some unique and complex system attributes, the current studies provide helpful insights into general sterilization methods by chemicals in the gaseous state. Both population recovery and fraction negative (FN) techniques were used to assay surviving populations from biological indicators of the organism Geobacillus stearothermophilus following exposure to incremental Chemiclave cycles. Models 5500 and 6000 of the Barnstead/Thermolyne Chemiclave were used in the study. Reusable instruments such as scalers, explorers, and various hinged pieces were tested in minimum versus maximum load studies. Population recovery study results demonstrated that lethality rates increase with time throughout the Chemiclave sterilization process and that there are significant variations in lethality according to load location. The population recovery data in conjunction with the FN studies and temperature data confirm that one-half the full-cycle time is not a good estimator of one-half the full-cycle lethality because lethality curves are concave downward and lethality varies by load location. This conclusion can also be applied to other types of gaseous, chemical sterilization such as ethylene oxide. The work outlined in this study was a result of investigations into the parameters affecting formaldehyde chemical vapor sterilization with the Harvey Chemiclave sterilizer. During these studies, it became apparent that results clearly depicted the effects of continued acceleration of the rate of microbial lethality, as well as variations in delivered lethality as a function of position in the sterilizer load. This publication focuses on these observations because they are

  11. Collective flow in Au + Au collisions

    SciTech Connect

    Ritter, H.G.; EOS Collaboration

    1994-05-01

    Based on a preliminary sample of Au + Au collisions in the EOS time projection chamber at the Bevalac, we study sideward flow as a function of bombarding energy between 0.25A GeV and 1.2A GeV. We focus on the increase in in-plane transverse momentum per nucleon with fragment mass. We also find event shapes to be close to spherical in the most central collisions, independent of bombarding energy and fragment mass up to {sup 4}He.

  12. IRIS Toxicological Review of Formaldehyde (Interagency Science Consultation Draft)

    EPA Science Inventory

    On June 2, 2010, the Toxicological Review of Formaldehyde and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices...

  13. An Alternative to Formaldehyde. Avoiding the Carcinogenic Risks.

    ERIC Educational Resources Information Center

    Ealy, Julie B.

    1991-01-01

    Demonstrations in which glyoxal may be substituted for formaldehyde, a known carcinogen, are presented. An acid-base clock reaction and a copper mirror on the inside of a test tube are described. Directions for the demonstrations and safety precautions are included. (KR)

  14. Concentrations of Glyoxal and Formaldehyde During CALNEX 2010

    NASA Astrophysics Data System (ADS)

    Henry, S. B.; Digangi, J. P.; Boyle, E.; Calnex Science Team

    2010-12-01

    Atmospheric oxidation of volatile organic compounds (VOCs) via the HOx-NOx cycle can lead to elevated concentrations of tropospheric ozone and secondary organic aerosol (SOA), both of which have been shown to be detrimental to human health. A detailed and mechanistic understanding of the VOC-HOx-NOx cycle is vital for improving the predictive capabilities of models for ozone and SOA. Accurate projection of oxidized VOCs is an important aspect of validating the photochemical mechanisms in models, which can then be used to evaluate regulation strategies. Glyoxal and formaldehyde are produced though oxidation of many important VOCs, and thus are powerful tracers of photooxidation via the HOx-NOx cycle. We report measurements of glyoxal and formaldehyde in Bakersfield, California located in the San Joaquin Valley during the CALNEX 2010 campaign (May 15th through June 30th). These measurements, with relevant trends and correlations, will be presented. Glyoxal:formaldehyde ratios will also be examined during this period. This ratio has been related to the source of VOCs dominating an air mass (i.e. anthropogenic versus biogenic). Both compounds were measured in situ with both high sensitivity and high temporal resolution (30 second) via laser induced emission techniques. Glyoxal was quantified by phosphorescence (MAD-LIP instrument) and formaldehyde by fluorescence (FILIF instrument). The measurements presented herein are useful for comparisons with current atmospheric models in order to evaluate the representation of photochemical oxidation in models. Furthermore, these data are also valuable points of comparison for satellite column retrieval data.

  15. BIOGENIC SOURCES FOR FORMALDEHYDE AND ACETALDEHYDE DURING SUMMER MONTHS

    EPA Science Inventory

    Photochemical modeling estimated contributions to ambient concentrations of formaldehyde and acetaldehyde from biogenic emissions over the continental United States during January 2001 (Eos Trans. AGU, 83(47), Fall Meet. Suppl., Abstract A52B-0117). Results showed that maximum co...

  16. The methods of formaldehyde emission testing of engine: A review

    NASA Astrophysics Data System (ADS)

    Zhang, Chunhui; Geng, Peng; Cao, Erming; Wei, Lijiang

    2015-12-01

    A number of measurements have been provided to detect formaldehyde in the atmosphere, but there are no clear unified standards in engine exhaust. Nowadays, formaldehyde, an unregulated emission from methanol engine, has been attracting increasing attention by researchers. This paper presents the detection techniques for formaldehyde emitted from the engines applied in recent market, introducing the approaches in terms of unregulated emission tests of formaldehyde, which involved gas chromatography, liquid chromatography, chromatography-mass spectrometry, chromatography-spectrum, Fourier infrared spectroscopy and spectrophotometry. The author also introduces the comparison regarding to the advantages of the existing detection techniques based on the principle, to compare with engine exhaust sampling method, the treatment in advance of detection, obtaining approaches accessing to the qualitative and quantitative analysis of chromatograms or spectra. The accuratest result obtained was chromatography though it cannot be used continuously. It also can be utilized to develop high requirements of emissions and other regulations. Fourier infrared spectroscopy has the advantage of continuous detection for a variety of unregulated emissions and can be applied to the bench in variable condition. However, its accuracy is not as good as chromatography. As the conclusion, a detection technique is chosen based on different requirements.

  17. Organocatalytic removal of formaldehyde adducts from RNA and DNA bases

    NASA Astrophysics Data System (ADS)

    Karmakar, Saswata; Harcourt, Emily M.; Hewings, David S.; Lovejoy, Alexander F.; Kurtz, David M.; Ehrenschwender, Thomas; Barandun, Luzi J.; Roost, Caroline; Alizadeh, Ash A.; Kool, Eric T.

    2015-09-01

    Formaldehyde is universally used to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here, we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, while avoiding the high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5-2.4-fold using a catalyst under optimized conditions and by 7-25-fold compared with a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens.

  18. Organocatalytic removal of formaldehyde adducts from RNA and DNA bases.

    PubMed

    Karmakar, Saswata; Harcourt, Emily M; Hewings, David S; Scherer, Florian; Lovejoy, Alexander F; Kurtz, David M; Ehrenschwender, Thomas; Barandun, Luzi J; Roost, Caroline; Alizadeh, Ash A; Kool, Eric T

    2015-09-01

    Formaldehyde is universally used to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here, we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, while avoiding the high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5-2.4-fold using a catalyst under optimized conditions and by 7-25-fold compared with a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens. PMID:26291948

  19. SORPTION AND REEMISSION OF FORMALDEHYDE BY GYPSUM WALLBOARD

    EPA Science Inventory

    The paper gives results of an analysis of the sorption and desorption of formaldehyde by unpainted wallboard, using a mass transfer model based on the Langmuir sorption isotherm. he sorption and desorption rate constants are determined by short-term experimental data. ong-term so...

  20. Engineering and Analysis of a Saccharomyces cerevisiae Strain That Uses Formaldehyde as an Auxiliary Substrate▿

    PubMed Central

    Baerends, Richard J. S.; de Hulster, Erik; Geertman, Jan-Maarten A.; Daran, Jean-Marc; van Maris, Antonius J. A.; Veenhuis, Marten; van der Klei, Ida J.; Pronk, Jack T.

    2008-01-01

    We demonstrated that formaldehyde can be efficiently coutilized by an engineered Saccharomyces cerevisiae strain that expresses Hansenula polymorpha genes encoding formaldehyde dehydrogenase (FLD1) and formate dehydrogenase (FMD), in contrast to wild-type strains. Initial chemostat experiments showed that the engineered strain coutilized formaldehyde with glucose, but these mixed-substrate cultures failed to reach steady-state conditions and did not exhibit an increased biomass yield on glucose. Subsequent transcriptome analyses of chemostat cultures of the engineered strain, grown on glucose-formaldehyde mixtures, indicated that the presence of formaldehyde in the feed caused biotin limitations. Further transcriptome analysis demonstrated that this biotin inactivation was prevented by using separate formaldehyde and vitamin feeds. Using this approach, steady-state glucose-limited chemostat cultures were obtained that coutilized glucose and formaldehyde. Coutilization of formaldehyde under these conditions resulted in an enhanced biomass yield of the glucose-limited cultures. The biomass yield was quantitatively consistent with the use of formaldehyde as an auxiliary substrate that generates NADH and subsequently, via oxidative phosphorylation, ATP. On an electron pair basis, the biomass yield increase observed with formaldehyde was larger than that observed previously for formate, which is tentatively explained by different modes of formate and formaldehyde transport in S. cerevisiae. PMID:18378663

  1. Formaldehyde treatment of proteins can constrain presentation to T cells by limiting antigen processing.

    PubMed Central

    di Tommaso, A; de Magistris, M T; Bugnoli, M; Marsili, I; Rappuoli, R; Abrignani, S

    1994-01-01

    Proteins to be used as vaccines are frequently treated with formaldehyde, although little is known about the effects of this treatment on protein antigenicity. To investigate the effect of formaldehyde treatment on antigen recognition by T cells, we compared the in vitro T-cell response to proteins that have been formaldehyde treated with the response to untreated proteins. We found that peripheral blood mononuclear cells from individuals vaccinated with three formaldehyde-treated proteins (pertussis toxin, filamentous hemagglutinin, pertactin) of Bordetella pertussis showed little or no response to the formaldehyde-treated proteins but proliferated very well in response to the corresponding untreated protein. These findings were further confirmed with CD4+ T-cell clones specific for defined epitopes of the bacterial proteins. We found that some epitopes are presented poorly or not at all when formaldehyde-treated proteins are used, whereas other epitopes are equally presented to T-cell clones when either formaldehyde-treated or untreated antigens are used. However, T-cell recognition could be restored by either antigen degradation before formaldehyde treatment or heat denaturation after such treatment. Parallel digestion with trypsin of both formaldehyde-treated and untreated proteins showed that fragments generated from the two forms of the same antigen were different in size. These results demonstrate that formaldehyde treatment can constrain antigen presentation to T cells and that this may be due to an altered proteolytic processing of formaldehyde-treated proteins. Images PMID:7513307

  2. A mathematical model for the absorption and metabolism of formaldehyde vapour by humans

    SciTech Connect

    Franks, S.J. . E-mail: Susan.Franks@hsl.gov.uk

    2005-08-15

    Epidemiological studies of occupational exposure to formaldehyde gas (HCHO) have suggested possible links between concentration and duration of exposure, and elevated risks of leukaemia and other cancers at sites distant from the site of contact. Formaldehyde is a highly water soluble gas which, when inhaled, reacts rapidly at the site of contact and is quickly metabolised by enzymes in the respiratory tissue. Inhaled formaldehyde is almost entirely absorbed in the respiratory tract and, for formaldehyde induced toxicity to occur at distant sites, HCHO must enter the blood and be transported to systemic tissues via the circulatory system. A mathematical model describing the absorption and removal of inhaled formaldehyde in the nasal tissue is therefore formulated to predict the proportion of formaldehyde entering into the blood. Accounting for the spatial distribution of the formaldehyde concentration and the metabolic activity within the mucosa, the concentration of formaldehyde in the mucus, the epithelium and the blood has been determined and was found to attain a steady-state profile within a few seconds of exposure. The increase of the formaldehyde concentration in the blood was predicted to be insignificant compared with the existing pre-exposure levels in the body, indicating that formaldehyde is rapidly removed in the nasal tissue. The results of the model thus suggest that it is highly unlikely that following inhalation by the nose, formaldehyde itself will cause toxicity at sites other than the initial site of contact in the respiratory tract.

  3. Adsorption and Reaction of Formaldehyde on Thin-film Cerium Oxide

    SciTech Connect

    Zhou,J.; Mullins, D.

    2006-01-01

    Formaldehyde adsorption and reaction have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The formaldehyde behavior was examined as a function of temperature, exposure and Ce oxidation state. Formaldehyde chemisorbs on fully oxidized CeO{sub 2} as dioxymethylene, CH{sub 2}O{sub 2}. The dioxymethylene decomposes and desorbs as formaldehyde between 200 K and 400 K. No other products are formed. On reduced ceria, formaldehyde also adsorbs as dioxymethylene. In addition to the formaldehyde desorption between 200 K and 400 K, a more strongly bound form of dioxymethylene is formed that produces formaldehyde at 440 K. Above 400 K, some of the dioxymethylene reacts to form formate and methoxy on the surface. These species decompose to produce H{sub 2}, CO and CH{sub 2}O above 500 K.

  4. Au-Free GaN High-Electron-Mobility Transistor with Ti/Al/W Ohmic and WN X Schottky Metal Structures for High-Power Applications

    NASA Astrophysics Data System (ADS)

    Hsieh, Ting-En; Lin, Yueh-Chin; Chu, Chung-Ming; Chuang, Yu-Lin; Huang, Yu-Xiang; Shi, Wang-Cheng; Dee, Chang-Fu; Majlis, Burhanuddin Yeop; Lee, Wei-I.; Chang, Edward Yi

    2016-04-01

    In this study, an Au-free AlGaN/GaN high-electron-mobility transistor (HEMT) with Ti/Al/W ohmic and WNx Schottky metal structures is fabricated and characterized. The device exhibits smooth surface morphology after metallization and shows excellent direct-current (DC) characteristics. The device also demonstrates better performance than the conventional HEMTs under high voltage stress. Furthermore, the Au-free AlGaN/GaN HEMT shows stable device performance after annealing at 400°C. Thus, the Ti/Al/W ohmic and WN X Schottky metals can be applied in the manufacturing of GaN HEMT to replace the Au based contacts to reduce the manufacturing costs of the GaN HEMT devices with comparable device performance.

  5. Au-Free GaN High-Electron-Mobility Transistor with Ti/Al/W Ohmic and WN X Schottky Metal Structures for High-Power Applications

    NASA Astrophysics Data System (ADS)

    Hsieh, Ting-En; Lin, Yueh-Chin; Chu, Chung-Ming; Chuang, Yu-Lin; Huang, Yu-Xiang; Shi, Wang-Cheng; Dee, Chang-Fu; Majlis, Burhanuddin Yeop; Lee, Wei-I.; Chang, Edward Yi

    2016-07-01

    In this study, an Au-free AlGaN/GaN high-electron-mobility transistor (HEMT) with Ti/Al/W ohmic and WN x Schottky metal structures is fabricated and characterized. The device exhibits smooth surface morphology after metallization and shows excellent direct-current (DC) characteristics. The device also demonstrates better performance than the conventional HEMTs under high voltage stress. Furthermore, the Au-free AlGaN/GaN HEMT shows stable device performance after annealing at 400°C. Thus, the Ti/Al/W ohmic and WN X Schottky metals can be applied in the manufacturing of GaN HEMT to replace the Au based contacts to reduce the manufacturing costs of the GaN HEMT devices with comparable device performance.

  6. Stabilized, superparamagnetic functionalized graphene/Fe3O4@Au nanocomposites for a magnetically-controlled solid-state electrochemiluminescence biosensing application.

    PubMed

    Gu, Wenling; Deng, Xi; Gu, Xiaoxiao; Jia, Xiaofang; Lou, Baohua; Zhang, Xiaowei; Li, Jing; Wang, Erkang

    2015-02-01

    Herein, a multifunctional nanoarchitecture has been developed by integrating the branched poly(ethylenimine) functionalized graphene/iron oxide hybrids (BGNs/Fe3O4) and luminol capped gold nanoparticles (luminol-AuNPs). The luminescent luminol-AuNPs as an electrochemiluminescence marker can be assembled on the nanocarrier of BGNs/Fe3O4 hybrids efficiently via the Au-N chemical bonds and electrostatic adsorption. Meanwhile, the multifunctional nanoarchitecture has been proved with excellent electron transfer, good stability, high emission intensity, etc. Furthermore, we successfully developed an ultrasensitive magnetically-controlled solid-state electrochemiluminescence (ECL) platform for label-free determination of HeLa cells using this multifunctional nanocomposite. Excellent performance of the magnetically-controlled ECL biosensing platform has been achieved including a high sensitivity for HeLa cells with a linear range from 20 to 1 × 10(4) cells/mL, good stability, and reproducibility. PMID:25541634

  7. Anthracycline-Formaldehyde Conjugates and Their Targeted Prodrugs

    NASA Astrophysics Data System (ADS)

    Koch, Tad H.; Barthel, Benjamin L.; Kalet, Brian T.; Rudnicki, Daniel L.; Post, Glen C.; Burkhart, David J.

    The sequence of research leading to a proposal for anthracycline cross-linking of DNA is presented. The clinical anthracycline antitumor drugs are anthraquinones, and as such are redox active. Their redox chemistry leads to induction of oxidative stress and drug metabolites. An intermediate in reductive glycosidic cleavage is a quinone methide, once proposed as an alkylating agent of DNA. Subsequent research now implicates formaldehyde as a mediator of anthracycline-DNA cross-linking. The cross-link at 5'-GC-3' sites consists of a covalent linkage from the amino group of the anthracycline to the 2-amino group of the G-base through a methylene from formaldehyde, hydrogen bonding from the 9-OH to the G-base on the opposing strand, and hydrophobic interactions through intercalation of the anthraquinone. The combination of these interactions has been described as a virtual cross-link of DNA. The origin of the formaldehyde in vivo remains a mystery. In vitro, doxorubicin reacts with formaldehyde to give firstly a monomeric oxazolidine, doxazolidine, and secondly a dimeric oxazolidine, doxoform. Doxorubicin reacts with formaldehyde in the presence of salicylamide to give the N-Mannich base conjugate, doxsaliform. Doxsaliform is several fold more active in tumor cell growth inhibition than doxorubicin, but doxazolidine and doxoform are orders of magnitude more active than doxorubicin. Exploratory research on the potential for doxsaliform and doxazolidine as targeted cytotoxins is presented. A promising lead design is pentyl PABC-Doxaz, targeted to a carboxylesterase enzyme overexpressed in liver cancer cells and/or colon cancer cells.

  8. Development of Formaldehyde Biosensor for Determination of Formalin in Fish Samples; Malabar Red Snapper (Lutjanus malabaricus) and Longtail Tuna (Thunnus tonggol).

    PubMed

    Noor Aini, Bohari; Siddiquee, Shafiquzzaman; Ampon, Kamaruzaman

    2016-01-01

    Electrochemical biosensors are widely recognized in biosensing devices due to the fact that gives a direct, reliable, and reproducible measurement within a short period. During bio-interaction process and the generation of electrons, it produces electrochemical signals which can be measured using an electrochemical detector. A formaldehyde biosensor was successfully developed by depositing an ionic liquid (IL) (e.g., 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][Otf])), gold nanoparticles (AuNPs), and chitosan (CHIT), onto a glassy carbon electrode (GCE). The developed formaldehyde biosensor was analyzed for sensitivity, reproducibility, storage stability, and detection limits. Methylene blue was used as a redox indicator for increasing the electron transfer in the electrochemical cell. The developed biosensor measured the NADH electron from the NAD⁺ reduction at a potential of 0.4 V. Under optimal conditions, the differential pulse voltammetry (DPV) method detected a wider linear range of formaldehyde concentrations from 0.01 to 10 ppm within 5 s, with a detection limit of 0.1 ppm. The proposed method was successfully detected with the presence of formalin in fish samples, Lutjanus malabaricus and Thunnus Tonggol. The proposed method is a simple, rapid, and highly accurate, compared to the existing technique. PMID:27376338

  9. Air formaldehyde and solvent concentrations during surface coating with acid-curing lacquers and paints in the woodworking and furniture industry.

    PubMed

    Thorud, Syvert; Gjolstad, Merete; Ellingsen, Dag G; Molander, Paal

    2005-06-01

    An investigation of contemporary exposure to formaldehyde and organic solvents has been carried out during surface coating with acid-curing lacquers and paints in the Norwegian woodworking and furniture industry over a period of 3 years. The investigation covered 27 factories of different sizes and with different types of production, and totally 557 parallel formaldehyde and solvent samples were collected. The formaldehyde concentration (geometric mean) was 0.15 ppm (range 0.01-1.48 ppm) with about 10% of the samples exceeding the Norwegian occupational exposure limit of 0.5 ppm. The solvent concentration as additive effect (geometric mean) was 0.13 (range 0.0004-5.08) and about 5% of the samples exceeded the Norwegian occupational exposure limit. The most frequently occurring solvents from acid-curing lacquers were n-butyl acetate, ethanol, ethyl acetate and 1-butanol, which were found in 88-98% of the samples. Toluene, n-butyl acetate and 1-butanol were the only solvents with maximum concentrations exceeding their respective occupational exposure limits. Curtain painting machine operators were exposed to the highest concentrations of both formaldehyde (geometric mean 0.51 ppm, range 0.08-1.48 ppm) and organic solvents (additive effect, geometric mean 1.18, range 0.02-5.08). Other painting application work tasks such as automatic and manual spray-painting, manual painting and dip painting, showed on average considerably lower concentrations of both formaldehyde (geometric means 0.07-0.16 ppm) and organic solvents (additive effect, geometric mean 0.02-0.18). Non-painting work tasks also displayed moderate concentrations of formaldehyde (geometric means 0.11-0.17 ppm) and organic solvents (additive effect, geometric mean 0.04-0.07). PMID:15931419

  10. Recognizing indoor formaldehyde in binary gas mixtures with a micro gas sensor array and a neural network

    NASA Astrophysics Data System (ADS)

    Lv, Pin; Tang, Zhenan; Wei, Guangfen; Yu, Jun; Huang, Zhengxing

    2007-09-01

    Low-concentration formaldehyde (HCHO) together with ethanol/toluene/acetone/α-pinene (as an interference gas of HCHO) is detected with a micro gas sensor array, composed of eight tin oxide (SnO2) thin film gas sensors with Au, Cu, Pt or Pd metal catalysts. The characteristics of the multi-dimensional signals from the eight sensors are evaluated. A multilayer neural network with an error backpropagation (BP) learning algorithm, plus the principal component analysis (PCA) technique, is implemented to recognize these indoor volatile organic compounds (VOC). The results show that the micro gas sensor array, plus the multilayer neural network, is very effective in recognizing 0.06 ppm HCHO in single gas component and in binary gas mixtures, toluene/ethanol/α-pinene with small relative error.

  11. Promotion effect of Pd on TiO2 for visible light photocatalytic degradation of gaseous formaldehyde.

    PubMed

    Wu, Ren-Jang; Liu, Yung-Shiuan; Lai, Hsiao-Fang; Wang, Jhe-Hao; Chavali, Murthy

    2014-09-01

    TiO2 and Pd doped TiO2 (Pd/TiO2) nanoparticles were prepared by sol gel method. Pd/TiO2 material was characterized by XRD, TEM, TPR, XPS and BET. From XRD data, the crystalline type of TiO2 is known to as Anatase type. TiO2 and Pd/TiO2 were in the order of 9-10 nm and 10-13 nm respectively. The photocatalytic activities of the TiO2 and Pd/TiO2 nanomaterials were evaluated and compared for the photodegradation of formaldehyde (HCHO). HCHO degradation on Pd/TiO2 catalyst, at 60 min, the degradation rate of gaseous HCHO is 95%. Using Pd/TiO2, the rate was faster than TiO2 or doped with other metals (Au/TiO2; Ag/TiO2; Pt/TiO2). PMID:25924333

  12. The synthesis of Au@C@Pt core-double shell nanocomposite and its application in enzyme-free hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Yayun; Li, Yuhui; Jiang, Yingying; Li, Yancai; Li, Shunxing

    2016-08-01

    A novel Au@C@Pt core-double shell nanocomposite was synthesized and used to fabricate enzyme-free electrochemical sensor for rapid and sensitive detection of hydrogen peroxide (H2O2). The well-designed Au@C@Pt core-double shell nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy-dispersed spectrum (EDS). The Au@C@Pt core-double shell nanocomposite modified glassy carbon electrode (Au@C@Pt/GCE) exhibits good electrocatalytic activity towards H2O2 reduction at 0.0 V and can be used as H2O2 sensor. The sensor displays two wide linear ranges towards H2O2 detection. The one is 9.0 μM-1.86 mM with high sensitivity of 144.7 μA mM-1 cm-2, and the other is 1.86 mM-7.11 mM with sensitivity of 80.1 μA mM-1 cm-2. When signal to noise (S/N) is 3, the calculated detection limit (LOD) is 0.13 μM. Furthermore, the interference from the common interfering species such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided to H2O2 detection. Additionally, the H2O2 sensor also displays good stability and reproducibility.

  13. Preparation and Characterization of Au-ZrO2-SiO2 Nanocomposite Spheres and Their Application in Enrichment and Detection of Organophosphorus Agents

    SciTech Connect

    Yang, Yuqi; Tu, Haiyang; Zhang, Aidong; Du, Dan; Lin, Yuehe

    2012-03-01

    Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized and used as selective sorbents for the solid-phase extraction (SPE) of orananophosphorous agents. A non-enzymatic electrochemical sensor based on an Au-ZrO{sub 2}-SiO{sub 2} modified electrode was developed for selective detection of orananophosphorous pesticides (OPs). The Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized by hydrolysis and condensation of zirconia n-butoxide (TBOZ) on the surface of SiO{sub 2} spheres and then introduction of gold nanoparticles on the surface. Transmission electron microscope and X-ray photoelectron spectroscopy were performed to characterize the formation of the nanocomposite sphere. Fast extraction of OP was achieved by Au-ZrO{sub 2}-SiO{sub 2} modified electrode within 5 min via the specific affinity between zirconia and phosphoric group. The assay yields a broad concentration range of paraoxon-ethyl from 1.0 to 500 ng/mL{sup -1} with a detection limit 0.5 ng/mL{sup -1}. This selective and sensitive method holds great promise for the enrichment and detection of OPs.

  14. Bioinspired polydopamine as the scaffold for the active AuNPs anchoring and the chemical simultaneously reduced graphene oxide: characterization and the enhanced biosensing application.

    PubMed

    Tian, Juan; Deng, Sheng-Yuan; Li, Da-Li; Shan, Dan; He, Wei; Zhang, Xue-Ji; Shi, You

    2013-11-15

    We report here an efficient approach to enhance the performance of biosensing platform based on graphene or graphene derivate. Initially, graphene oxides (GO) nanosheets were reduced and surface functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced graphene oxides (PDRGO). The bioinspired surface was further used as a support to anchor active gold nanoparticles (AuNPs). The morphology and structure of the as-prepared AuNPs/PDRGO nanocomposite were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR). Electrochemical studies demonstrate that the as-prepared AuNPs/PDRGO hybrid materials possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH at low potential (0.1 V vs. SCE) with the fast response (15s) and the broad linear range (5.0 × 10(-8)-4.2 × 10(-5)M). Thus, this AuNPs/PDRGO nanocomposite can be further used to fabricate a sensitive alcohol biosensor using alcohol dehydrogenase (ADH), by simply incorporating the specific enzyme within the composite matrix with the aid of chitosan (Chit). PMID:23811480

  15. Ag-Modified In₂O₃/ZnO Nanobundles with High Formaldehyde Gas-Sensing Performance.

    PubMed

    Fang, Fang; Bai, Lu; Song, Dongsheng; Yang, Hongping; Sun, Xiaoming; Sun, Hongyu; Zhu, Jing

    2015-01-01

    Ag-modified In2O3/ZnO bundles with micro/nano porous structures have been designed and synthesized with by hydrothermal method continuing with dehydration process. Each bundle consists of nanoparticles, where nanogaps of 10-30 nm are present between the nanoparticles, leading to a porous structure. This porous structure brings high surface area and fast gas diffusion, enhancing the gas sensitivity. Consequently, the HCHO gas-sensing performance of the Ag-modified In2O3/ZnO bundles have been tested, with the formaldehyde-detection limit of 100 ppb (parts per billion) and the response and recover times as short as 6 s and 3 s, respectively, at 300 °C and the detection limit of 100 ppb, response time of 12 s and recover times of 6 s at 100 °C. The HCHO sensing detect limitation matches the health standard limitation on the concentration of formaldehyde for indoor air. Moreover, the strategy to synthesize the nanobundles is just two-step heating and easy to scale up. Therefore, the Ag-modified In2O3/ZnO bundles are ready for industrialization and practical applications. PMID:26287205

  16. An investigation of the radiolytic stability of a resorcinol- formaldehyde ion exchange resin

    SciTech Connect

    Crawford, C.L.; Bibler, N.E.; Bibler, J.P.

    1993-12-31

    Radiolytic stability of a resorcinol-formaldehyde polycondensation-type cation exchange resin was investigated for up to lE09 rads total dose. The resorcinol-formaldehyde resin is a resin that has potential cesium decontamination applications at Pacific Northwest and Savannah River. We have determined both radiation and storage effects on performance of the resin using 101-AW Hanford simulant and ASTM Type-I water. Distribution coefficient determinations, total carbon analysis, and physical observations lead us to conclude that radiation up to lE08 rads does not significantly affect the performance of the resin. The resin is more stable to radiation in water than in 101-AW Hanford simulant. Also radiation or storage does not affect the thermal stability of the resin. Gas production rates for several resin slurries increased in the order of resin/101-AW Hanford simulant, resin/ASTM water, and resin/0.5 M HNO{sub 3}. H{sub 2} is produced from radiolysis of resin in 101-AW Hanford simulant with a G value of G(H{sub 2}) of 0.11 {plus_minus} 0.02 molecules/100eV and in 0.5 M HNO{sub 3} with a G value of G(H{sub 2}) of 0.27 {plus_minus} 0.02 molecules/lOOeV.

  17. Sub-ppb detection of formaldehyde with cantilever enhanced photoacoustic spectroscopy using quantum cascade laser source

    NASA Astrophysics Data System (ADS)

    Hirschmann, C. B.; Lehtinen, J.; Uotila, J.; Ojala, S.; Keiski, R. L.

    2013-06-01

    A novel cantilever enhanced photoacoustic spectrometer with mid-infrared quantum cascade laser was applied for selective and sensitive formaldehyde (CH2O) gas measurement. The spectrum of formaldehyde was measured from 1,772 to 1,777 cm-1 by tuning the laser with a spectral resolution of 0.018 cm-1. The band at 1,773.959 cm-1 was selected for data analysis, at which position the laser emitted 47 mW. In univariate measurement, the detection limit (3 σ, 0.951 s) and the normalized noise equivalent absorption coefficient (3 σ) for amplitude modulation (AM) were 1.6 ppbv and 7.32 × 10-10 W cm-1 (Hz)-1/2 and for wavelength modulation (WM) 1.3 ppbv and 6.04 × 10-10 W cm-1 (Hz)-1/2. In multivariate measurement, the detection limit (3 σ) can be as low as 901 pptv (1,773.833-1,774.085 cm-1, 15 spectral points each 0.951 s) for AM and 623 pptv (1,773.743-1,774.265 cm-1, 30 spectral points each 0.951 s) for WM. Because measurement time increases in multivariate measurement, its application is justified only when interferents need to be resolved. Potential improvements of the system are discussed.

  18. Phenol-formaldehyde resin substitutes from biomass tars

    SciTech Connect

    Himmelblau, D.A.

    1995-11-01

    Approximately 320,000 tonnes of phenol and formaldehyde are currently used annually in North America to make adhesive resins that are used to make exterior-grade structural panels. The demand for phenol-formaldehyde (PF) resins is growing faster than the demand for panels, because more adhesive is required to join/coat the surface of wood flakes (for oriented strand board - OSB) than is required to join veneer; OSB is replacing plywood as logs large enough for veneer become scarcer. Also, competitive uses for phenol and methanol (for making formaldehyde) have increased raw materials cost and threatened availability. Production of adhesive resins from biomass to reduce reliance on raw materials derived from commodity petrochemicals and to lower resin cost looks attractive. A simple fluidized-bed reactor system can be used to produce tars that can substitute for a major portion of the phenol and formaldehyde in PF resin adhesives. This can be done in an air-fluidized, single-bed reactor; no inert gas or dual-bed system is required. The key is recognizing that optimum phenolic character in the tar is not produced at the maximum tar yield, but at reactor temperatures around 600{degrees}C and short gas-phase residence times that produce a yield of about 25 to 30 weight percent. A wide range of phenols, aldehydes and other compounds capable of polymerization are produced. Feedstock can be any wood waste larger than sander dust; low cost agricultural wastes such as bagasse are also suitable. Adhesive resin is produced from the entire tar product by shifting the pH from acidic to basic with NaOH, and combining and heating the resulting resole with phenol and formaldehyde, similarly to conventional resins. Approximately half of the phenol and formaldehyde by weight can be replaced with tar. A plant producing 13,865,000 kg (30,566,000 lb) annually from 308 tonnes (340 tons) per day of green wood chips would cost approximately $8,400,000.

  19. Gold catalysts supported on nanosized iron oxide for low-temperature oxidation of carbon monoxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Tang, Zheng; Zhang, Weidong; Li, Yi; Huang, Zuming; Guo, Huishan; Wu, Feng; Li, Jinjun

    2016-02-01

    This study aimed to optimize synthesis of gold catalyst supported on nanosized iron oxide and to evaluate the activity in oxidation of carbon monoxide and formaldehyde. Nanosized iron oxide was prepared from a colloidal dispersion of hydrous iron oxide through a dispersion-precipitation method. Gold was adsorbed onto nanosized iron oxide under self-generated basic conditions. Characterization results indicate that the iron oxide consisted of hematite/maghemite composite with primary particle sizes of 6-8 nm. Gold was highly dispersed on the surface of the support. The catalysts showed good activity in the oxidation of airborne carbon monoxide and formaldehyde. The optimal pH for their synthesis was ∼7. The catalytic performance could be enhanced by extending the adsorption time of gold species on the support within 21 h. The optimized catalyst was capable of achieving complete oxidation of 1% carbon monoxide at -20 °C and 33% conversion of 450 ppm formaldehyde at ambient temperature. The catalyst may be applicable to indoor air purification.

  20. Hydraulic Permeability of Resorcinol-Formaldehyde Resin

    SciTech Connect

    Taylor, Paul Allen

    2010-01-01

    An ion exchange process using spherical resorcinol-formaldehyde (RF) resin is the baseline process for removing cesium from the dissolved salt solution in the high-level waste tanks at the Hanford Site, using large scale columns as part of the Waste Treatment Plant (WTP). The RF resin is also being evaluated for use in the proposed small column ion exchange (SCIX) system, which is an alternative treatment option at Hanford and at the Savannah River Site (SRS). A recirculating test loop with a small ion exchange column was used to measure the effect of oxygen uptake and radiation exposure on the permeability of a packed bed of the RF resin. The lab-scale column was designed to be prototypic of the proposed Hanford columns at the WTP. Although the test equipment was designed to model the Hanford ion exchange columns, the data on changes in the hydraulic permeability of the resin will also be valuable for determining potential pressure drops through the proposed SCIX system. The superficial fluid velocity in the lab-scale test (3.4-5.7 cm/s) was much higher than is planned for the full-scale Hanford columns to generate the maximum pressure drop expected in those columns (9.7 psig). The frictional drag from this high velocity produced forces on the resin in the lab-scale tests that matched the design basis of the full-scale Hanford column. Any changes in the resin caused by the radiation exposure and oxygen uptake were monitored by measuring the pressure drop through the lab-scale column and the physical properties of the resin. Three hydraulic test runs were completed, the first using fresh RF resin at 25 C, the second using irradiated resin at 25 C, and the third using irradiated resin at 45 C. A Hanford AP-101 simulant solution was recirculated through a test column containing 500 mL of Na-form RF resin. Known amounts of oxygen were introduced into the primary recirculation loop by saturating measured volumes of the simulant solution with oxygen and reintroducing

  1. Formaldehyde-releasers in cosmetics: relationship to formaldehyde contact allergy. Part 1. Characterization, frequency and relevance of sensitization, and frequency of use in cosmetics.

    PubMed

    de Groot, Anton C; White, Ian R; Flyvholm, Mari-Ann; Lensen, Gerda; Coenraads, Pieter-Jan

    2010-01-01

    In this part of a series of review articles on formaldehyde-releasers and their relationship to formaldehyde contact allergy, formaldehyde-releasers in cosmetics are discussed. In this first part of the article, key data are presented including frequency of sensitization and of their use in cosmetics. In Europe, low frequencies of sensitization have been observed to all releasers: 2-bromo-2-nitropropane-1,3-diol 0.4-1.2%, diazolidinyl urea 0.5-1.4%, imidazolidinyl urea 0.3-1.4%, quaternium-15 0.6-1.9% (for DMDM hydantoin no recent data are available). All releasers score (far) higher prevalences in the USA; the possible explanations for this are discussed. The relevance of positive patch test reactions has been insufficiently investigated. In the USA, approximately 20% of cosmetics and personal care products (stay-on products: 17%, rinse-off products 27%) contain a formaldehyde-releaser. The use of quaternium-15 is decreasing. For Europe, there are no comparable recent data available. In the second part of the article, the patch test relationship of the releasers in cosmetics to formaldehyde contact allergy will be reviewed and it will be assessed whether products preserved with formaldehyde-releasers may contain enough free formaldehyde to pose a threat to individuals who have contact allergy to formaldehyde. PMID:20136875

  2. 40 CFR Appendix A to Subpart Hhhh... - Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced & Cooled) A Appendix A to Subpart HHHH of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS...

  3. 40 CFR Appendix A to Subpart Hhhh... - Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... samples that decompose to yield formaldehyde under the conditions of other free-formaldehyde methods. The... g methanol). 2.2.5Sodium chloride (NaCl) (reagent grade). 2.2.6Sodium hydroxide (NaOH). 2.3Procedure... American Chemical Society analytical reagent grade or better. 3.2.1One 1-liter (L) volumetric flask...

  4. 40 CFR Appendix A to Subpart Hhhh... - Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced & Cooled) A Appendix A to Subpart HHHH of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS...

  5. 40 CFR Appendix A to Subpart Hhhh... - Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Method for Determining Free-Formaldehyde in Urea-Formaldehyde Resins by Sodium Sulfite (Iced & Cooled) A Appendix A to Subpart HHHH of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS...

  6. B36 borophene as an electronic sensor for formaldehyde: Quantum chemical analysis

    NASA Astrophysics Data System (ADS)

    Shahbazi Kootenaei, Amirhossein; Ansari, Goodarz

    2016-08-01

    Pristine carbon nanotubes and graphene show great sensitivity toward several lethal gases but cannot identify some extremely toxic chemicals such as formaldehyde (HCOH). Recent successful synthesis of all-boron graphene-like sheets attracted strong interest in exploring their possible applications. Herein, we inspected the potential application of B36 borophene sheet as a sensor for HCOH detection, using density functional theory computations. Different theoretical levels including B97D and Minnesota 06 functionals with different basis sets were employed. It was predicted that the electrical conductivity of B36 borophene significantly increases at the presence of HCOH molecules, thereby generating an electrical signal. The electrical signal is increased by increasing the number of adsorbed HCOH molecules, indicating that this sensor is sensitive to the concentration (or pressure) of HCOH gas. These results suggest that the pristine borophene may be used in the HCOH chemical sensors.

  7. Phoxim Microcapsules Prepared with Polyurea and Urea-Formaldehyde Resins Differ in Photostability and Insecticidal Activity.

    PubMed

    Zhang, Da-Xia; Li, Bei-Xing; Zhang, Xian-Peng; Zhang, Zheng-Qun; Wang, Wei-Chang; Liu, Feng

    2016-04-13

    The application of pesticide microcapsules (MCs) in agriculture is becoming more and more popular. In this study, the effects of different wall materials on the stomach toxicity, contact toxicity, length of efficacy, and photolysis characteristics of pesticide microcapsules were investigated. The results showed that microencapsulation reduced the stomach and contact toxicities of phoxim and prolonged the efficacy of this light-sensitive chemical in the greenhouse test. Neither of the degradation curves for microencapsulated phoxim under ultraviolet light fit a first-order model, although the emulsifiable concentrate (EC) degradation curve fit it well. The phoxim-loaded polyurea microcapsules (PUA-MCs) showed significantly increased UV-resistance ability, stomach toxicity, and contact toxicity compared with the phoxim-loaded urea-formaldehyde microcapsules (UF-MCs). These experiments indicated that it is crucial to select the appropriate wall materials for pesticide microcapsules on the basis of application sites and physicochemical properties of pesticide active ingredients. PMID:27010712

  8. Using microkinetic analysis to search for novel anhydrous formaldehyde production catalysts

    NASA Astrophysics Data System (ADS)

    Li, Han-Jung; Lausche, Adam C.; Peterson, Andrew A.; Hansen, Heine A.; Studt, Felix; Bligaard, Thomas

    2015-11-01

    Direct dehydrogenation of methanol to produce anhydrous formaldehyde is investigated using periodic density functional theory (DFT) and combining the microkinetic model to estimate rates and selectivities on stepped (211) surfaces under a desired reaction condition. Binding energies of reaction intermediates and transition state energies for each elementary reaction can be accurately scaled with CHO and OH binding energies as the only descriptors. Based on these two descriptors, a steady-state microkinetic model is constructed with a piecewise adsorbate-adsorbate interaction model that explicitly includes the effects of adsorbate coverage on the rates and selectivities as well as the volcano plots are obtained. Our results show that most of the stepped (211) pure-metallic surfaces such as Au, Pt, Pd, Rh, Ru, Ni, Fe, and Co are located in a region of low activity and selectivity toward CH2O production due to higher rate for CH2O dehydrogenation than CH2O desorption. The selectivities toward CH2O production on Zn, Cu, and Ag surfaces are located on the boundary between the high and low selectivity regions. To find suitable catalysts for anhydrous CH2O production, a large number of A3B-type transition metal alloys are screened based on their predicted rates and selectivities, as well as their estimated stabilities and prices. We finally propose several promising candidates for the dehydrogenation of CH3OH.

  9. An Engineering Evaluation of Spherical Resorcinol Formaldehyde Resin

    SciTech Connect

    Birdwell Jr, Joseph F; Lee, Denise L; Taylor, Paul Allen; Collins, Robert T; Hunt, Rodney Dale

    2010-09-01

    A small column ion exchange (SCIX) system has been proposed for removal of cesium from caustic, supernatant, and dissolved salt solutions stored or generated from high-level tank wastes at the US Department of Energy (DOE) Hanford Site and Savannah River Sites. In both instances, deployment of SCIX systems, either in-tank or near-tank, is a means of expediting waste pretreatment and dispositioning with minimal or no new infrastructure requirements. Conceptually, the treatment approach can utilize a range of ion exchange media. Previously, both crystalline silicotitanate (CST), an inorganic, nonelutable sorbent, and resorcinol-formaldehyde (RF), an organic, elutable resin, have been considered for cesium removal from tank waste. More recently, Pacific Northwest National Laboratory (PNNL) evaluated use of SuperLig{reg_sign} 644, an elutable ion exchange medium, for the subject application. Results of testing indicate hydraulic limitations of the SuperLig{reg_sign} resin, specifically a high pressure drop through packed ion exchange columns. This limitation is likely the result of swelling and shrinkage of the irregularly shaped (granular) resin during repeated conversions between sodium and hydrogen forms as the resin is first loaded then eluted. It is anticipated that a similar flow limitation would exist in columns packed with conventional, granular RF resin. However, use of spherical RF resin is a likely means of mitigating processing limitations due to excessive pressure drop. Although size changes occur as the spherical resin is cycled through loading and elution operations, the geometry of the resin is expected to effectively mitigate the close packing that leads to high pressure drops across ion exchange columns. Multiple evaluations have been performed to determine the feasibility of using spherical RF resin and to obtain data necessary for design of an SCIX process. The work performed consisted of examination of radiation effects on resin performance

  10. Electrospun nanofibrous chitosan membranes modified with polyethyleneimine for formaldehyde detection.

    PubMed

    Wang, Na; Wang, Xianfeng; Jia, Yongtang; Li, Xiaoqi; Yu, Jianyong; Ding, Bin

    2014-08-01

    Here we describe a formaldehyde sensor fabricated by coating polyethyleneimine (PEI) functionalized chitosan nanofiber-net-binary structured layer on quartz crystal microbalance (QCM). The chitosan fibrous substrate comprising nanofibers and spider-web-like nano-nets constructed by a facile electro-spinning/netting process provided an ideal structure for the uniform PEI modification and sensing performance enhancement. Benefiting from the fascinating nanostructure, abundant primary amine groups of PEI, and strong adhesive force to the QCM electrode of PEI-chitosan membranes, the developed formaldehyde sensor presented rapid response and low detection limit (5 ppm) at room temperature. These findings have important implications in fabricating multi-dimensional nanostructures on QCM for gas sensing and chemical analysis. PMID:24751264

  11. Simple, rapid method for the preparation of isotopically labeled formaldehyde

    DOEpatents

    Hooker, Jacob Matthew; Schonberger, Matthias; Schieferstein, Hanno; Fowler, Joanna S.

    2011-10-04

    Isotopically labeled formaldehyde (*C.sup..sctn.H.sub.2O) is prepared from labeled methyl iodide (*C.sup..sctn.H.sub.3I) by reaction with an oxygen nucleophile having a pendant leaving group. The mild and efficient reaction conditions result in good yields of *C.sup..sctn.H.sub.2O with little or no *C isotopic dilution. The simple, efficient production of .sup.11CH.sub.2O is described. The use of the .sup.11CH.sub.2O for the formation of positron emission tomography tracer compounds is described. The reaction can be incorporated into automated equipment available to radiochemistry laboratories. The isotopically labeled formaldehyde can be used in a variety of reactions to provide radiotracer compounds for imaging studies as well as for scintillation counting and autoradiography.

  12. Tentative identification of formaldehyde in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    Korablev, O. I.; Ackerman, M.; Krasnopolsky, V. A.; Moroz, V. I.; Muller, C.; Rodin, A. V.; Atreya, S. K.

    1993-06-01

    Solar occultation observations of the Martian atmosphere near the limb of the planet were performed during the Phobos mission by means of the Auguste infrared spectrometer in the ranges 2707-2740 and 5392-5272/cm with a resolving power of approximately = 1300. The spectra exhibit features at 2710 and 2730/cm which have not been identified previously. After applying a set of corrections to the data and examining the spectra of various molecules, we are led to conclude that the best candidate for the above-mentioned features is formaldehyde (CH2O). It was observed in eight of the nine successful occultation sequences, mainly between 8 and 20 km with an average mixing ratio of 0.5 (+0.8, - 0.3) ppm (there are no good data below 8 km). The observations are performed in equatorial spring conditions. The altitude distribution of formaldehyde reveals correlation with the permanent haze opacity.

  13. Molecularly Imprinted Polymer Nanoparticles for Formaldehyde Sensing with QCM

    PubMed Central

    Hussain, Munawar; Kotova, Kira; Lieberzeit, Peter A.

    2016-01-01

    Herein, we report on molecularly imprinted polymers (MIPs) for detecting formaldehyde vapors in air streams. A copolymer thin film consisting of styrene, methacrylic acid, and ethylene glycol dimethacrylate on quartz crystal microbalance (QCM) yielded a detection limit of 500 ppb formaldehyde in dry air. Surprisingly, these MIPs showed specific behavior when tested against a range of volatile organic compounds (VOCs), such as acetaldehyde, methanol, formic acid, and dichloromethane. Despite thus being a suitable receptor in principle, the MIPs were not useful for measurements at 50% humidity due to surface saturation by water. This was overcome by introducing primary amino groups into the polymer via allyl amine and by changing the coating morphology from thin film to nanoparticles. This led to the same limit of detection (500 ppb) and selectivity as before, but at the real-life conditions of 50% relative humidity. PMID:27376287

  14. Formaldehyde and Glyoxal: New Products in the SCIAMACHY Operational Processor

    NASA Astrophysics Data System (ADS)

    Hrechanyy, Serhiy; de Smedt, Isabelle; Kretschel, Klaus; Lichtenberg, Günter; Meringer, Markus; Wittrock, Folkard

    In sommer of 2010 version 6 of the SCIAMACHY operational processor is planned to be deliv-ered to ESA. The SCIAMACHY Quality Working Group recommended an implementation of the formalde-hyde (HCHO) and glyoxal (CHOCHO) vertical columns into version 6 of the off-line processor. They are formed during the oxidation of volatile organic compounds (VOCs) emitted by plants, anthropogenic activities, and biomass burning. Due to a rather short lifetime of formaldehyde and glyoxal, their distribution maps, obtained by the SCIAMACHY, represent the emission fields of their precursors, VOCs. The descriptions of reference algorithm as well as all the cross-sections for formaldehyde and glyoxal retrievals were delivered to DLR by the Belgian Institute for Space Aeronomy (BIRA) (I. De Smedt, 2008) and by the IUP (F. Wittrock, 2006), respectively. Both retrievals are based on the DOAS technique. For the formaldehyde retrieval the spectral region of 328.5-346 nm was recommended. The absorption cross-sections of HCHO, O3, NO2, BrO, OClO, a Ring spectrum and a polynomial of the fifth order are included into the fitting procedure. Before conversion to the vertical columns, the slant columns have to be normal-ized by subtracting the slant columns measured over Pacific ocean, where the only source of formaldehyde is methane oxidation. After the conversion to the vertical columns, part of HCHO removed during the previous procedure has to be re-added to the final vertical column by adding of the mean vertical column calculated by the tropospheric chemistry model IMAGES (J.-F. Müller, 1995). This normalization is necessary to compensate for the offset introduced by the solar reference measurements and interferences by other absorbers. For the determination of glyoxal columns, the spectral region 435-457 nm was selected. In this case, the absorption cross-sections of CHOCHO, O3, NO2, H2O, O4, a Ring spectrum and a cubic polynomial are included in the fitting procedure. The normalization of

  15. Phase Space Structures Explain Hydrogen Atom Roaming in Formaldehyde Decomposition.

    PubMed

    Mauguière, Frédéric A L; Collins, Peter; Kramer, Zeb C; Carpenter, Barry K; Ezra, Gregory S; Farantos, Stavros C; Wiggins, Stephen

    2015-10-15

    We re-examine the prototypical roaming reaction--hydrogen atom roaming in formaldehyde decomposition--from a phase space perspective. Specifically, we address the question "why do trajectories roam, rather than dissociate through the radical channel?" We describe and compute the phase space structures that define and control all possible reactive events for this reaction, as well as provide a dynamically exact description of the roaming region in phase space. Using these phase space constructs, we show that in the roaming region, there is an unstable periodic orbit whose stable and unstable manifolds define a conduit that both encompasses all roaming trajectories exiting the formaldehyde well and shepherds them toward the H2···CO well. PMID:26499774

  16. Intercomparison of Formaldehyde Measurements during BEACHON ROCS 2010

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Digangi, J. P.; Schnitzhofer, R.; Herdlinger-Blatt, I. S.; Karl, T.; Graus, M.; Turnipseed, A.; Keutsch, F. N.; Hansel, A.; Beachon-Rocs Science Team

    2011-12-01

    The BEACHON (Biosphere-hydrosphere-atmosphere-interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen) long term research initiative was established to shed light on sources, sinks and the atmospheric fate of organic aerosol and precursor gases. The BEACHON-Rocky mountain Organic Carbon Study (BEACHON-ROCS) focused on the biosphere-atmosphere exchange of reactive organic gases in a rural coniferous forest northwest of Colorado Springs, CO, during August 2010. Formaldehyde (HCHO) is an important tracer of VOC oxidation as it is formed during atmospheric oxidation of biogenic VOCs such as isoprene and other terpenes. Here we present measurements of formaldehyde conducted by two independent instruments, the Madison Fiber Laser Induced Flourescence (FILIF) Instrument and a Proton Transfer Reaction Time of Flight mass spectrometer (PTR-TOF-MS). Both instruments simultaneously measured HCHO concentrations at high temporal resolution potentially allowing for eddy covariance flux calculations. The comparison between FILIF and PTR-TOF-MS suggests generally good agreement.

  17. Molecularly Imprinted Polymer Nanoparticles for Formaldehyde Sensing with QCM.

    PubMed

    Hussain, Munawar; Kotova, Kira; Lieberzeit, Peter A

    2016-01-01

    Herein, we report on molecularly imprinted polymers (MIPs) for detecting formaldehyde vapors in air streams. A copolymer thin film consisting of styrene, methacrylic acid, and ethylene glycol dimethacrylate on quartz crystal microbalance (QCM) yielded a detection limit of 500 ppb formaldehyde in dry air. Surprisingly, these MIPs showed specific behavior when tested against a range of volatile organic compounds (VOCs), such as acetaldehyde, methanol, formic acid, and dichloromethane. Despite thus being a suitable receptor in principle, the MIPs were not useful for measurements at 50% humidity due to surface saturation by water. This was overcome by introducing primary amino groups into the polymer via allyl amine and by changing the coating morphology from thin film to nanoparticles. This led to the same limit of detection (500 ppb) and selectivity as before, but at the real-life conditions of 50% relative humidity. PMID:27376287

  18. Observations of formaldehyde in Comet Machholtz (1988j)

    NASA Technical Reports Server (NTRS)

    Snyder, Lewis E.; Palmer, Patrick; De Pater, Imke

    1990-01-01

    Comet Machholtz's 1(11)-1(10) formaldehyde emission was detected with the VLA in September, 1988 at 6-cm wavelength; the small blueshift of -0.76 + or - 0.40 km/sec noted by these observations is consistent with an anisotropic outgassing of the cometary nucleus in the solar direction. The derived formaldehyde production rate for Comet Halley, which exhibits a similar emission line blueshift, was 1.5 x 10 to the 28th mol/sec, while for Comet Machholtz the production rate is about an order of magnitude higher, at 2 x 10 to the 29th mol/sec. The fading of Comet Machholtz after these observations is ascribed to its breakup.

  19. Tentative identification of formaldehyde in the Martian atmosphere

    NASA Technical Reports Server (NTRS)

    Korablev, O. I.; Ackerman, M.; Krasnopolsky, V. A.; Moroz, V. I.; Muller, C.; Rodin, A. V.; Atreya, S. K.

    1993-01-01

    Solar occultation observations of the Martian atmosphere near the limb of the planet were performed during the Phobos mission by means of the Auguste infrared spectrometer in the ranges 2707-2740 and 5392-5272/cm with a resolving power of approximately = 1300. The spectra exhibit features at 2710 and 2730/cm which have not been identified previously. After applying a set of corrections to the data and examining the spectra of various molecules, we are led to conclude that the best candidate for the above-mentioned features is formaldehyde (CH2O). It was observed in eight of the nine successful occultation sequences, mainly between 8 and 20 km with an average mixing ratio of 0.5 (+0.8, - 0.3) ppm (there are no good data below 8 km). The observations are performed in equatorial spring conditions. The altitude distribution of formaldehyde reveals correlation with the permanent haze opacity.

  20. Enzymatic synthesis of C-11 formaldehyde: concise communication

    SciTech Connect

    Slegers, G.; Lambrecht, R.H.D.; Vandewalle, T.; Meulewaeter, L.; Vandecasteele, C.

    1984-03-01

    An enzymatic synthesis of C-11 formaldehyde from C-11 methanol is presented, with immobilized alcohol oxidase and catalase: a rapid, simple procedure, with a high and reproducible yield. Carbon-11 methanol is oxidized to C-11 formaldehyde by passage over a column on which the enzymes alcohol oxidase and catalase are immobilized. The catalase increases reaction velocity by recycling the oxygen, and prevents destruction of the alcohol oxidase by eliminating the excess of hydrogen peroxide. The yield of the enzyme-catalyzed oxidation was 80-95%. A specific activity of 400-450 mCi/..mu..mole was obtained at EOB + 20 min. Various immobilization techniques and the optimal reaction conditions of the immobilized enzymes are investigated.

  1. Terahertz spectroscopy of deuterated formaldehyde using a frequency multiplication chain

    NASA Astrophysics Data System (ADS)

    Zakharenko, Olena; Motiyenko, Roman A.; Margulès, Laurent; Huet, Thérèse R.

    2015-11-01

    The rotational spectra of deuterated formaldehyde HDCO and D2CO were recorded between 1.1 and 1.52 THz in order to benchmark new terahertz frequency multiplication chain used in the Lille spectrometer. Important spectrometer parameters such as sensitivity, measurement accuracy, and harmonic composition of the radiation source have been tested using the newly measured spectra. For each of the main deuterated isotopic species of formaldehyde the existent datasets from high resolution measurements were augmented by more than 300 new distinct transition frequencies. Most of these frequencies were measured with an accuracy better than 30 kHz. In addition, the high sensitivity of the spectrometer provided by the new frequency multiplication chain allowed observation, assignment and analysis of 13C, 17O, 18O, and 13C18O isotopic species of HDCO and D2CO. For some of these isotopologues the rotational parameters were determined for the first time.

  2. A cucurbit[5]uril analogue from dimethylpropanediurea-formaldehyde condensation.

    PubMed

    Jiang, Xiaoqing; Yao, Xuyang; Huang, Xinghua; Wang, Qiaochun; Tian, He

    2015-02-18

    A new host was prepared for the first time from propanediurea-formaldehyde condensation. is soluble in both water and common organic solvents, and binds protonated amines in a 1 : 2 stoichiometry in H2O with the K1 and K2 values on the order of 10(3) M(-1). The self-assembly of with 1,4-xylylene diamine dihydrochloride results in the formation of a linear supramolecular polymer. PMID:25582698

  3. SONEX-Hydrogen Peroxide, Methylhydroperoxide and Formaldehyde Measurements

    NASA Technical Reports Server (NTRS)

    Heikes, Brian

    1999-01-01

    We measured gas phase H2O2, CH3OOH, and CH2O on board the NASA DC-8 during the SONEX field mission, presented preliminary results at three scientific meetings, participated in two data workshops and contributed to joint publications of final results. The observations of peroxides and formaldehyde were instrumental in assessing odd-hydrogen radical chemistry, ozone chemistry, and in tracing meteorological transport paths.

  4. MCSCF potential energy surface for photodissociation of formaldehyde

    NASA Technical Reports Server (NTRS)

    Jaffe, R. L.; Morokuma, K.

    1976-01-01

    The ground state potential energy surface for the dissociation of formaldehyde (H2CO to H2 and CO) is calculated with the ab initio MCSCF method with an extended (4-31G) basis set. The location, barrier height, and force constants of the transition state are determined, and the normal coordinate analysis is carried out. The calculated barrier height is 4.5 eV. Based on the calculated quantities, the detailed mechanism of the photochemical dissociation is discussed.

  5. Testing a steam-formaldehyde sterilizer for gas penetration efficiency

    PubMed Central

    Line, Stuart J.; Pickerill, J. K.

    1973-01-01

    A test piece is described for monitoring the performance of low-temperature steam-with-formaldehyde sterilizers. Comparative tests have shown it to be more difficult to penetrate than an arterial catheter when exposed to the same sterilizing conditions. It is permanent and simple to use and maintain. The growth or non-growth of bacterial spores, in the convenient form of spore strips, is used to indicate the efficacy of sterilization. PMID:4752414

  6. Biodegradation of polystyrene, poly(metnyl methacrylate), and phenol formaldehyde.

    PubMed Central

    Kaplan, D L; Hartenstein, R; Sutter, J

    1979-01-01

    The biodegradation of three synthetic 14C-labeled polymers, poly(methyl methacrylate), phenol formaldehyde, and polystyrene, was studied with 17 species of fungi in axenic cultures, five groups of soil invertebrates, and a variety of mixed microbial communities including sludges, soils, manures, garbages, and decaying plastics. Extremely low decomposition rates were found. The addition of cellulose and mineral failed to increase decomposition rates significantly. PMID:533278

  7. The Gas-Phase Deuterium Fractionation of Formaldehyde

    NASA Astrophysics Data System (ADS)

    Osamura, Yoshihiro; Roberts, Helen; Herbst, Eric

    2005-03-01

    The dominant mechanism for the deuteration of formaldehyde in the gas phase of low-temperature interstellar cloud cores occurs via reaction with the deuterating ions H2D+, HD+2, and D+3. Until now, it has been assumed that deuteration leads to an ion that, on recombination with electrons, can produce a deuterated neutral species with a statistical branching fraction. Quantum chemical calculations reported here, however, show an entirely different picture, in which the deuteration of formaldehyde leads to the molecular ion H2COD+, where the deuterium binds only on the oxygen side of the molecule. The structure is quite stable, while an alternative structure, H2DCO+, cannot be produced in a straightforward manner. Dissociative recombination of H2COD+ to reproduce a formaldehyde structure then removes the deuteration if the dissociation is direct, i.e., it occurs without change of structure. There are several possible indirect mechanisms by which dissociative recombination can lead to HDCO, however. For example, if the direct products are HCOD+H, it is possible that subsequent isomerization to HDCO can occur, although this involved process is unlikely. Another possibility is isomerization during the actual dissociation of the H2COD intermediate. Models of deuterium fractionation in which dissociative recombination is predominantly direct are presented, and it is found that the deuterium fractionation of formaldehyde to form both HDCO and D2CO can still occur via other mechanisms, although with less efficiency than previously obtained. If the dissociative recombination is half indirect, however, then we can recover the previously calculated efficiency.

  8. Formaldehyde Distribution over North America: Implications for Satellite Retrievals of Formaldehyde Columns and Isoprene Emission

    NASA Technical Reports Server (NTRS)

    Millet, Dylan B.; Jacob, Daniel J.; Turquety, Solene; Hudman, Rynda C.; Wu, Shiliang; Anderson, Bruce E.; Fried, Alan; Walega, James; Heikes, Brian G.; Blake, Donald R.; Singh, Hanwant B.; Clarke, Antony D.

    2006-01-01

    Formaldehyde (HCHO) columns measured from space provide constraints on emissions of volatile organic compounds (VOCs). Quantitative interpretation requires characterization of errors in HCHO column retrievals and relating these columns to VOC emissions. Retrieval error is mainly in the air mass factor (AMF) which relates fitted backscattered radiances to vertical columns and requires external information on HCHO, aerosols, and clouds. Here we use aircraft data collected over North America and the Atlantic to determine the local relationships between HCHO columns and VOC emissions, calculate AMFs for HCHO retrievals, assess the errors in deriving AMFs with a chemical transport model (GEOS-Chem), and draw conclusions regarding space-based mapping of VOC emissions. We show that isoprene drives observed HCHO column variability over North America; HCHO column data from space can thus be used effectively as a proxy for isoprene emission. From observed HCHO and isoprene profiles we find an HCHO molar yield from isoprene oxidation of 1.6 +/- 0.5, consistent with current chemical mechanisms. Clouds are the primary error source in the AMF calculation; errors in the HCHO vertical profile and aerosols have comparatively little effect. The mean bias and 1Q uncertainty in the GEOS-Chem AMF calculation increase from <1% and 15% for clear skies to 17% and 24% for half-cloudy scenes. With fitting errors, this gives an overall 1 Q error in HCHO satellite measurements of 25-31%. Retrieval errors, combined with uncertainties in the HCHO yield from isoprene oxidation, result in a 40% (1sigma) error in inferring isoprene emissions from HCHO satellite measurements.

  9. The study on the application of solid-state method for synthesizing the polyaniline/noble metal (Au or Pt) hybrid materials.

    PubMed

    Jamal, Ruxangul; Xu, Feng; Shao, Weiwei; Abdiryim, Tursun

    2013-01-01

    The solid-state method was applied for synthesizing polyaniline (PANI)/noble metal hybrid materials with the presence of HAuCl4·4H2O or H2PtCl6·6H2O in the reaction medium. The structure, morphology, and electrochemical activity of the composites were characterized by Fourier transform infrared (FTIR) spectra, UV-visible (vis) absorption spectra, energy dispersive spectrum (EDS), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cyclic voltammetry. The results from FTIR and UV-vis spectra showed that the oxidation degree and doping level of the PANI in composites can be influenced by HAuCl4·4H2O and H2PtCl6·6H2O. The EDS data demonstrated that the composites contain a certain amount of Au (or Pt) element. XRD analysis indicated the presence of crystalline-state Au particles in PANI matrix prepared from the presence of HAuCl4·4H2O and revealed that the H2PtCl6·6H2O cannot be converted into metal Pt. The TEM and SEM images implied that the Au particles did exist in the polymer matrix with the size of about 20 nm. The enzymeless H2O2 sensor constructed with PANI/Au composite from the presence of HAuCl4·4H2O showed a short response time (within 5 s) and displayed an excellent performance in wide linear range. PMID:23452667

  10. Catalytic purification of wastewaters containing formaldehyde, methyl alcohol, and acetone

    SciTech Connect

    Rachkovskaya, L.N.; Anisiforov, G.I.; Levitskii, E.A.; Kundo, N.N.

    1982-01-10

    A catalytic method for purification of wastewaters containing alcohols, aldehydes, and ketones is described in the literature. A current of steam containing gaseous organic compounds is passed over a complete-oxidation catalyst at temperatures of 250-700/sup 0/C. The organic compounds are oxidized to carbon dioxide. The main drawback of this method is that the wastewater must be evaporated and the vapor heated to high temperatures, involving a high consumption of fuel. Methods of liquid-phase catalytic oxidation under pressure are free from this drawback. A patent describes liquid-phase oxidation of phenol, analine, nitrobenzene, glycol, and dimethylformamide at temperatures of 275-300/sup 0/C under air pressures up to 100 atm in presence of oxides of copper, chromium, and zinc; a metallic catalyst consisting of copper, chromium, and manganese; copper oxide deposited on magnesium silicate. In a contact time of 8-10 min the degree of oxidation is 90-99%. It is known that liquid-phase oxidation of formaldehyde without a catalyst at 200/sup 0/C and 120 atm with a contact time of 4 h results in 80% oxidation of formaldehyde to methyl formate undergoes 10% conversion into acetic acid, while methyl alcohol is not oxidized at all. In this communication we describe liquid-phase catalytic oxidation of model wastewater containing formaldehyde, methyl alcohol, and acetone at temperatures up to 250/sup 0/C and oxygen pressures up to 20 atm.

  11. Formaldehyde and acetaldehyde emissions from residential wood combustion in Portugal

    NASA Astrophysics Data System (ADS)

    Cerqueira, Mário; Gomes, Luís; Tarelho, Luís; Pio, Casimiro

    2013-06-01

    A series of experiments were conducted to characterize formaldehyde and acetaldehyde emissions from residential combustion of common wood species growing in Portugal. Five types of wood were investigated: maritime pine (Pinus pinaster), eucalyptus (Eucalyptus globulus), cork oak (Quercus suber), holm oak (Quercus rotundifolia) and pyrenean oak (Quercus pyrenaica). Laboratory experiments were performed with a typical wood stove used for domestic heating in Portugal and operating under realistic home conditions. Aldehydes were sampled from diluted combustion flue gas using silica cartridges coated with 2,4-dinitrophenylhydrazine and analyzed by high performance liquid chromatography with diode array detection. The average formaldehyde to acetaldehyde concentration ratio (molar basis) in the stove flue gas was in the range of 2.1-2.9. Among the tested wood types, pyrenean oak produced the highest emissions for both formaldehyde and acetaldehyde: 1772 ± 649 and 1110 ± 454 mg kg-1 biomass burned (dry basis), respectively. By contrast, maritime pine produced the lowest emissions: 653 ± 151 and 371 ± 162 mg kg-1 biomass (dry basis) burned, respectively. Aldehydes were sampled separately during distinct periods of the holm oak wood combustion cycles. Significant variations in the flue gas concentrations were found, with higher values measured during the devolatilization stage than in the flaming and smoldering stages.

  12. Occupational exposure to formaldehyde in a medical center autopsy service

    SciTech Connect

    Coldiron, V.R.; Ward, J.B. Jr.; Trieff, N.M.; Janssen, H.E. Jr.; Smith, J.H.

    1983-07-01

    The formaldehyde exposures occurring in the autopsy service of a medical complex were evaluated as part of a study to detect genetically harmful effects of chemical exposures. Determination of time-weighted average (TWA) exposures and characterization of the patterns of exposure experienced by individuals with different work responsibilities in this occupational setting were sought. Both general area and breathing zone samples were evaluated. Estimated weekly time-weighted average exposures for pathologists, residents and technicians were determined to be between 0.61 and 1.32 parts per million with little difference between work roles. While the averages were similar, the patterns of exposure of technicians and physicians were different. Technicians were exposed to a baseline level of formaldehyde for a prolonged period of time. In contrast, physicians were exposed for shorter times but experienced higher levels during specific tasks, particularly tissue-sectioning and examination. Evaluations of work procedures and environmental conditions in autopsy services are recommended to reduce personnel exposure to formaldehyde vapor.

  13. Low-density carbonized resorcinol-formaldehyde foams. Final report

    SciTech Connect

    Kong, F.M.; Buckley, S.R.; Giles, C.L. Jr.; Haendler, B.L.; Hair, L.M.; Letts, S.A.; Overturf, G.E. III; Price, C.W.; Cook, R.C.

    1991-07-04

    This report documents research and development on resorcinol- formaldehyde-based foam materials conducted between 1986 and June 1990, when the effort was discontinued. The foams discussed are resorcinol-formaldehyde (RF) foam, carbonized RF (CRF) foam, and two composite foams, a polystyrene/RF (PS/RF) foam and its carbonized derivative (CPR). The RF foams are synthesized by the polycondensation of resorcinol with formaldehyde in a slightly basic solution. Their structure and density depend strongly on the concentration of the sodium carbonate catalyst. The have an interconnected bead structure similar to that of silica aerogels; bead sizes range from 30 to 130 {Angstrom}, and cell sizes are less than 0.1 {mu}m. We have achieved densities of 16 to 200 mg/cm{sup 3}. The RF foams can be pyrolyzed in an inert atmosphere to form a vitreous carbon foam (CRF), which has a similar microstructure but much higher mechanical strength. The PS/RF foams are obtained by filling the 2- to 3-{mu}m cells of PS foam (a low-density hydrocarbon foam we have developed) with RF. The resultant foams have the outstanding handling and machinability of the PS foam matrix and the small cell size of RF. Pyrolyzing PS/RF foams causes depolymerization and loss of the PS; the resulting CPR foams have a structure similar to the PS foams in which CRF both replicates and fills the PS cells.

  14. Low-density carbonized resorcinol-formaldehyde foams

    SciTech Connect

    Kong, F.M.; Buckley, S.R.; Giles, C.L. Jr.; Haendler, B.L.; Hair, L.M.; Letts, S.A.; Overturf, G.E. III; Price, C.W.; Cook, R.C.

    1991-07-04

    This report documents research and development on resorcinol- formaldehyde-based foam materials conducted between 1986 and June 1990, when the effort was discontinued. The foams discussed are resorcinol-formaldehyde (RF) foam, carbonized RF (CRF) foam, and two composite foams, a polystyrene/RF (PS/RF) foam and its carbonized derivative (CPR). The RF foams are synthesized by the polycondensation of resorcinol with formaldehyde in a slightly basic solution. Their structure and density depend strongly on the concentration of the sodium carbonate catalyst. The have an interconnected bead structure similar to that of silica aerogels; bead sizes range from 30 to 130 {Angstrom}, and cell sizes are less than 0.1 {mu}m. We have achieved densities of 16 to 200 mg/cm{sup 3}. The RF foams can be pyrolyzed in an inert atmosphere to form a vitreous carbon foam (CRF), which has a similar microstructure but much higher mechanical strength. The PS/RF foams are obtained by filling the 2- to 3-{mu}m cells of PS foam (a low-density hydrocarbon foam we have developed) with RF. The resultant foams have the outstanding handling and machinability of the PS foam matrix and the small cell size of RF. Pyrolyzing PS/RF foams causes depolymerization and loss of the PS; the resulting CPR foams have a structure similar to the PS foams in which CRF both replicates and fills the PS cells.

  15. Codetermination of crystal structures at high pressure: Combined application of theory and experiment to the intermetallic compound AuGa2

    NASA Astrophysics Data System (ADS)

    Godwal, B. K.; Stackhouse, S.; Yan, J.; Speziale, S.; Militzer, Burkhard; Jeanloz, R.

    2013-03-01

    A combination of x-ray diffraction at high pressures and first-principles calculations reveals the sequence of crystal-structural phase transitions in AuGa2 from cubic (Fm3¯m) to orthorhombic (Pnma) at 10 (±4) GPa and then to monoclinic (P21/n) at 33 (±6) GPa. Neither theory nor experiment would have been adequate, on their own, in documenting this sequence of phases, but together they confirm a sequence differing from the Fm3¯m→Pnma→P63/mmc transitions predicted for CaF2 and Pnma → P1121/a transition reported for PbCl2 and SnCl2. The combined results from theory and experiment also allow us to constrain the equations of state of the three phases of AuGa2. Calculations on the analog PbCl2 predict a transition to the P21/n phase seen in AuGa2 that could, therefore, be a common high-pressure phase for PbCl2-structured compounds.

  16. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    NASA Astrophysics Data System (ADS)

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-02-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K-B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10-15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K-B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source.

  17. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    DOE PAGESBeta

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-02-23

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DACmore » can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. In conclusion, the coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source.« less

  18. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures.

    PubMed

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S; Weidner, Donald J

    2016-01-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K-B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10-15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K-B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source. PMID:26902122

  19. High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

    PubMed Central

    Hong, Xinguo; Ehm, Lars; Zhong, Zhong; Ghose, Sanjit; Duffy, Thomas S.; Weidner, Donald J.

    2016-01-01

    We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source. PMID:26902122

  20. Green synthesis, characterization of Au-Ag core-shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    NASA Astrophysics Data System (ADS)

    Kirubha, E.; Palanisamy, P. K.

    2014-12-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au-Ag bimetallic core-shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au-Ag nanoparticles are characterized using UV-Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 109. The nonlinear optical parameters such as the nonlinear refractive index n2, nonlinear absorption coefficient β and the third order nonlinear susceptibility χ3 are measured for various wavelengths from 700 nm to 950 nm. The Au-Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G.

  1. The Vital Function of Fe3O4@Au nanocomposites for Hydrolase Biosensor Design and Its Application in Detection of Methyl Parathion

    SciTech Connect

    Zhao, Yuting; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-02-04

    A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH–NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike inhibition-based enzyme biosensors, the hydrolase is not poisoned by OPs and thus is reusable for continuous measurement. AuNPs not only provide a large surface area, high loading efficiency and fast electron transfer, but also stabilize the enzyme through electrostatic interactions. The MPH biosensor shows rapid response and high selectivity for detection of methyl parathion, with a linear range from 0.5 to 1000 ng/mL and a detection limit of 0.1 ng/mL. It also shows acceptable reproducibility and stability. The simplicity and ease of operation of the proposed method has great potential for on-site detection of P–S containing pesticides and provides a promising strategy to construct a robust biosensor.

  2. Extraction and preconcentration of formaldehyde in water by polypyrrole-coated magnetic nanoparticles and determination by high-performance liquid chromatography.

    PubMed

    Safari, Meysam; Yamini, Yadollah; Tahmasebi, Elham; Latifeh, Farzad

    2015-10-01

    In this study, a simple and rapid extraction method based on the application of polypyrrole-coated Fe3 O4 nanoparticles as a magnetic solid-phase extraction sorbent was successfully developed for the extraction and preconcentration of trace amounts of formaldehyde after derivatization with 2,4-dinitrophenylhydrazine. The analyses were performed by high-performance liquid chromatography followed by UV detection. Several variables affecting the extraction efficiency of the formaldehyde, i.e., sample pH, amount of sorbent, salt concentration, extraction time and desorption conditions were investigated and optimized. The best working conditions were as follows: sample pH, 5; amount of sorbent, 40 mg; NaCl concentration, 20% w/v; sample volume, 20 mL; extraction time, 12 min; and 100 μL of methanol for desorption of the formaldehyde within 3 min. Under the optimal conditions, the performance of the proposed method was studied in terms of linear dynamic range (10-500 μg/L), correlation coefficient (R(2) ≥ 0.998), precision (RSD% ≤ 5.5) and limit of detection (4 μg/L). Finally, the developed method was successfully applied for extraction and determination of formaldehyde in tap, rain and tomato water samples, and satisfactory results were obtained. PMID:26205228

  3. Physicochemical behavior of sulphonated acetone-formaldehyde resin and naphthalene sulfonate-formaldehyde condensate in coal-water interface

    SciTech Connect

    Zhou, M.S.; Qiu, X.Q.; Yang, D.J.; Ouyang, X.P.

    2009-07-01

    This article studies the physicochemical characteristic of two anionic dispersants sulphonated acetone-formaldehyde resin (SAF) and naphthalene sulfonate-formaldehyde condensate (FDN) at coal-water interface, including contact angle, adsorption amount, thickness of adsorbed film, and zeta potential, using four different ranks of coals. The results show that SAF has better wetting property than FDN on coal surface. The adsorption amount of SAF in coal-water interface is greater than that of FDN, and that the thickness of adsorbed films of SAF and FDN on Datong coal measured by x-ray photoelectron spectroscopy (XPS) are respectively 6.38nm and 2.11nm. Moreover, the measurements of zeta potentials in coal-water interface show that SAF has greater capacity in charging coal surface with electronegativity. Based on the investigation, the adsorption models of SAF and FDN on different rank of coals are presented.

  4. Electrocatalytic oxidation of small organic molecules on Pt-Au nanoparticles supported by POMAN-MWCNTs

    NASA Astrophysics Data System (ADS)

    Dong, Qi-Zhi; Li, Li-Li; Chen, Qian-Shan; Guo, Can-Cheng; Yu, Gang

    2015-08-01

    Poly ( o-methoxyaniline) and multi-wall carbon nanotube composite (POMAN-MWCNT) films were deposited onto the platinum (Pt) electrode surface by cyclic voltammetry (CV). Then, platinum and gold (Au) nano-particles were deposited by CV and the double potential deposition method to modify the composite film on the Pt electrode. The morphology of the composite film was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and its electrocatalytic activity toward methanol and formaldehyde oxidation was studied by CV and other electrochemical methods. The results demonstrated that Pt-Au/POMAN-MWCNTs obtained by the double potential deposition method had a much higher catalytic activity and better anti-poisoning property for electrooxidation of methanol and formaldehyde. The improved catalytic performance could be attributed to the uniformly distribution of duel-metal nanoparticles and the synergistic effect between Pt and Au metals. The abstract should briefly state the problem or purpose of the research, indicate the methodology used, summarize the principal findings and major conclusions.

  5. Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes

    PubMed Central

    Dannemiller, Karen C.; Murphy, Johnna S.; Dixon, Sherry L.; Pennell, Kelly G.; Suuberg, Eric M.; Jacobs, David E.; Sandel, Megan

    2013-01-01

    Formaldehyde is a colorless, pungent gas commonly found in homes that is a respiratory irritant, sensitizer, carcinogen and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-minute grab samples in length-of-stain detector tubes in homes (n=70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5–132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (p<0.05), as well as temperature and household cleaner use (p<0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (p=0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296

  6. Possible prebiotic synthesis of monosaccharides from formaldehyde in presence of phosphates

    NASA Astrophysics Data System (ADS)

    Simonov, A. N.; Pestunova, O. P.; Matvienko, L. G.; Snytnikov, V. N.; Snytnikova, O. A.; Tsentalovich, Yu. P.; Parmon, V. N.

    Condensation of formaldehyde and lower carbohydrates (glycolaldehyde, glyceraldehyde, and dihydroxyacetone) is effectively catalyzed by heterogeneous and homogeneous phosphates in neutral aqueous medium. The interaction of formaldehyde and dihydroxyacetone leads to the preferential formation of 3-pentulose and erythrulose with yields of 40% and 45%, respectively. In absence of formaldehyde, the condensation of glycolaldehyde and glyceraldehyde catalyzed by phosphates leads to the formation of ribose and fructose. We demonstrate the possibility of formation of higher monosaccharides from pure formaldehyde in the course of the combined photochemical and phosphate-catalyzed reactions in plausible prebiotic conditions.

  7. On-line detection of atmospheric formaldehyde by a conductometric biosensor.

    PubMed

    Vianello, Fabio; Boscolo-Chio, Raffaella; Signorini, Stefano; Rigo, Adelio

    2007-01-15

    Atmospheric formaldehyde (CH(2)O) was detected under continuous flow conditions by an on-line system comprising of a wet scrubber for a continuous transfer of the pollutant to an aqueous solution, a micro-reactor containing immobilized formaldehyde dehydrogenase (FDH) and a conductometric transducer. By this system atmospheric formaldehyde concentrations in the range 0.05-2 ppm were detected with a sensitivity of 20 microS/ppm. In this concentration range the immobilized enzyme oxidized all the sampled formaldehyde molecules to formic acid, avoiding cumbersome calibration procedures. The operational stability of the biosensor was at least 3 months, working continuously 10 h/day at room temperature. PMID:16678399

  8. Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes.

    PubMed

    Dannemiller, K C; Murphy, J S; Dixon, S L; Pennell, K G; Suuberg, E M; Jacobs, D E; Sandel, M

    2013-08-01

    Formaldehyde is a colorless, pungent gas commonly found in homes and is a respiratory irritant, sensitizer, carcinogen, and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-min grab samples in length-of-stain detector tubes in homes (n = 70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5 to 132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (P < 0.05), as well as temperature and household cleaner use (P < 0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (P = 0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296

  9. A Formaldehyde Exposure Assessment Tool for Occupants of FEMA Temporary Housing Units

    SciTech Connect

    Parthasarathy, Srinandini; Spears, Michael; Maddalena, Randy L.; Russell, Marion L; Apte, Michael G.

    2010-10-01

    The report outlines the methodology used to develop a web-based tool to assess the formaldehyde exposure of the occupants of Federal Emergency Management Administration (FEMA) temporary housing units (THUs) after Hurricanes Katrina and Rita in 2005. Linear regression models were built using available data to retrospectively estimate the indoor temperature and relative humidity, formaldehyde emission factors and concentration, and hence the formaldehyde exposures. The interactive web-tool allows the user to define the inputs to the model to evaluate formaldehyde exposures for different scenarios.

  10. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates.

    PubMed

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-07-14

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. PMID:27315144

  11. Examination of the chemical changes in cured phenol-formaldehyde resins during storage.

    PubMed

    Strzemiecka, B; Zięba-Palus, J; Voelkel, A; Lachowicz, T; Socha, E

    2016-04-01

    Chemical changes occurring within cured phenol-formaldehyde resins (resite and novolak type) during their storage were investigated by FT-NIR, py-GCMS and inverse gas chromatography. It was shown that a mixture of resite with novolak was less stable than resite or novolak itself as regards bulk properties. This aging phenomenon is mainly due to reaction of ammonia (product of hexa decomposition) with CH2OH groups present in resite. FT-NIR technique seems to be the least sensitive method for assessment chemical changes occurring during cured resins storage. Applications of py-GCMS and IGC method made able to indicate that more significant changes were for bulk samples (py-GCMS results) than on their surface (IGC results). PMID:26961916

  12. ExoMol line lists - VIII. A variationally computed line list for hot formaldehyde

    NASA Astrophysics Data System (ADS)

    Al-Refaie, Ahmed F.; Yachmenev, Andrey; Tennyson, Jonathan; Yurchenko, Sergei N.

    2015-04-01

    A computed line list for formaldehyde, H212C16O, applicable to temperatures up to T = 1500 K is presented. An empirical potential energy and ab initio dipole moment surfaces are used as the input to the nuclear motion program TROVE. The resulting line list, referred to as AYTY, contains 10.3 million rotational-vibrational states and around 10 billion transition frequencies. Each transition includes associated Einstein-A coefficients and absolute transition intensities, for wavenumbers below 10 000 cm-1 and rotational excitations up to J = 70. Room-temperature spectra are compared with laboratory measurements and data currently available in the HITRAN data base. These spectra show excellent agreement with experimental spectra and highlight the gaps and limitations of the HITRAN data. The full line list is available from the CDS data base as well as at www.exomol.com.

  13. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  14. The vital function of Fe3O4@Au nanocomposites for hydrolase biosensor design and its application in detection of methyl parathion

    NASA Astrophysics Data System (ADS)

    Zhao, Yuting; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-01-01

    A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH-NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike inhibition-based enzyme biosensors, the hydrolase is not poisoned by OPs and thus is reusable for continuous measurement. AuNPs not only provide a large surface area, high loading efficiency and fast electron transfer, but also stabilize the enzyme through electrostatic interactions. The MPH biosensor shows rapid response and high selectivity for detection of methyl parathion, with a linear range from 0.5 to 1000 ng mL-1 and a detection limit of 0.1 ng mL-1. It also shows acceptable reproducibility and stability. The simplicity and ease of operation of the proposed method has great potential for on-site detection of P-S containing pesticides and provides a promising strategy to construct a robust biosensor.A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH-NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike

  15. Urine formaldehyde level is inversely correlated to mini mental state examination scores in senile dementia.

    PubMed

    Tong, Zhiqian; Zhang, Jinling; Luo, Wenhong; Wang, Weishan; Li, Fangxu; Li, Hui; Luo, Hongjun; Lu, Jing; Zhou, Jiangning; Wan, You; He, Rongqiao

    2011-01-01

    It is widely known that exogenous formaldehyde exposure induces human cognitive impairment and animal memory loss; and recent studies show that formaldehyde at pathological levels induces Aβ deposition and misfolding of tau protein to form globular amyloid-like aggregates. Endogenous formaldehyde may be a marker for progressive senile dementia. The aim of this study was to investigate the correlation of endogenous formaldehyde in urine of senile dementia and mini mental state examination (MMSE) scores. Formaldehyde level was analyzed by high-performance liquid chromatography (with fluorescence detection) in human urine from dementia patients (n=141), patients with hypertension (n=33) or diabetes (n=16) and healthy individuals (n=38), autopsy hippocampus samples from Alzheimer's disease (AD) patients and brains of three types of AD animal model: namely, senescence accelerated mice (SAMP8), APP-transgenic mice and APP/PS1-transgenic mice. In a double-blind study, there was marked elevation of urine formaldehyde levels in patients (n=91) with dementia, and a slight increase in patients (n=50) with mild cognitive impairment. Urine formaldehyde level was inversely correlated with mini mental state examination scores (Rs=-0.441, p<0.0001). Furthermore, formaldehyde levels were significantly increased in the autopsy hippocampus from Alzheimer's patients (n=4). In SAMP8 brains the formaldehyde level was significantly increased, suggesting that the endogenous formaldehyde is related to aging in mice. The brain formaldehyde level in APP/PS1-transgenic (n=8) mice at age of 3 months and APP-transgenic (n=8) mice at age of 6 months was increased (0.56 ± 0.02 mM), respectively, as compared with their respective age-matched controls, when these two types of AD-like animals, respectively, started to form Aβ deposits and memory loss obviously. According to the level of formaldehyde in the brain of the transgenic mice, we treated normal mice with formaldehyde (0.5m

  16. Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

    PubMed

    Ahmed, Hanan B; Zahran, M K; Emam, Hossam E

    2016-10-01

    Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method. PMID:27212212

  17. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  18. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  19. Reduction of graphene oxide by 100 MeV Au ion irradiation and its application as H2O2 sensor

    NASA Astrophysics Data System (ADS)

    Hareesh, K.; Joshi, R. P.; Shateesh, B.; Asokan, K.; Kanjilal, D.; Late, D. J.; Dahiwale, S. S.; Bhoraskar, V. N.; Haram, S. K.; Dhole, S. D.

    2015-09-01

    Graphene oxide (GO) synthesized from a modified Hummer’s method was reduced (referred, rGO) by using 100 MeV Au ion species and its response to the sense H2O2 was investigated. The changes in the atomic composition and structural properties of rGO after irradiation were studied using x-ray diffraction, Fourier transform infrared spectroscopy and x-ray photo-electron spectroscopy. These results suggested that the removal of the oxygen-containing functional groups and the improvement of the electrochemical performance of reduced graphene oxide (rGO) after ion irradiation. Raman spectroscopic results revealed the increase in the disorder parameter (I D/I G) after Au ion irradiation and also the formation of a large number of small sp2 domains due to the electronic energy loss of ion beam. The resultant rGO was investigated for H2O2 sensing using electrochemical techniques and it showed a good response.

  20. Novel photoswitchable dielectric properties on nanomaterials of electronic core-shell γ-FeOx@Au@fullerosomes for GHz frequency applications.

    PubMed

    Wang, Min; Su, Chefu; Yu, Tzuyang; Tan, Loon-Seng; Hu, Bin; Urbas, Augustine; Chiang, Long Y

    2016-03-28

    We unexpectedly observed a large amplification of the dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the interface on samples of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)](n)2 nanoparticles (NPs) in frequencies of 0.5-4.0 GHz. The detected relative dielectric constant amplification was initiated upon switching off the light followed by relaxation to give an excellent recyclability. These NPs having e(-)-polarizable fullerosomic structures located at the outer layer were fabricated from highly magnetic core-shell γ-FeOx@AuNPs. Surface-stabilized 2 in a core-shell structure was found to be capable of photoinducing the surface plasmonic resonance (SPR) effect by white LED light. The accumulated SPR energy was subsequently transferred to the partially bilayered C60(>DPAF-C9) fullerosomic membrane layer in a near-field (∼1.5 nm) region without producing radiation heat. Since the monostatic SAR signal is dielectric property-dependent, we used these measurements to provide evidence of derived reflectivity changes on a surface coated with 2 at 0.5-4.0 GHz upon illumination of LED white light. We found that a high, >99%, efficiency of response amplification in image amplitude can be achieved. PMID:26936772

  1. M\\TiO₂ (M=Au, Ag) transparent aqueous sols and its application on polymeric surface antibacterial post-treatment.

    PubMed

    Wu, Liangzhuan; Yu, Yuan; Song, Le; Zhi, Jinfang

    2015-05-15

    In this paper, we reported a simple and mild chemical method for synthesis of crystalline metal\\TiO2 (M=Au, Ag) transparent aqueous sols at low temperature (80°C). It should be found that the as-synthesized metal\\TiO2 sols could easily be coated on the flexible PET surfaces of the through the as-developed electroless-plating-like solution deposition (EPLSD) procedure. The as-prepared metal\\TiO2 sols and related flexible thin film were characterized by TEM, SEM, XRD, UV-vis, and FTIR analysis. The results showed that the Au and Ag nanoparticles can significantly improve the optical absorption properties of TiO2 due to the surface plasmon generated by the noble metal, which in turn enhanced the photo-induced antibacterial performance of the as-prepared metal\\TiO2 flexible film. Moreover, the photo-generated electrons could transfer between the metal and titanium dioxide under different irradiation (ultraviolet or visible light), which could significantly reduce the recombination of photo-induced electrons and holes, resulting in the better photo-induced antibacterial performance. Therefore, the EPLSD procedure may be used as a general polymeric surface antibacterial post-treatment procedure for preparing the metal\\TiO2 flexible film because of the noble metal enhanced antibacterial performance. PMID:25678155

  2. Roaming Under the Microscope: Trajectory Study of Formaldehyde Dissociation.

    PubMed

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2016-07-14

    The photodissociation of formaldehyde was studied using quasi-classical trajectories to investigate "roaming," or events involving trajectories that proceed far from the minimum energy pathway. Statistical analysis of trajectories performed over a range of nine excitation energies from 34 500 to 41 010 cm(-1) (including zero-point energy) provides characterization of the roaming phenomenon and insight into the mechanism. The trajectories are described as projections onto three coordinates: the distance from the CO center of mass to the furthest H atom and the azimuthal and polar coordinates of that H atom with respect to the CO axis. The trajectories are used to construct a "minimum energy" potential energy surface showing the potential for any binary combination of these three coordinates that is at a minimum energy with respect to values of the other coordinates encountered during the trajectories. We also construct flux diagrams for roaming, transition-state, and radical pathways, as well as "reaction configuration" plots that show the distribution of reaction geometries for roaming and transition-state pathways. These constructs allow characterization of roaming in formaldehyde as, principally, internal rotation of the roaming H atom around the CO axis at a slowly varying and elongated distance from the CO center of mass. The rotation is nearly uniform, and is sometimes accompanied by rotation in the polar coordinate. The roaming state of formaldehyde can be treated as a separate kinetic entity, much as one might treat an isomer. Rate constants for the formation of and reaction from this roaming state are derived from the trajectory data as a function of excitation energy. PMID:26885745

  3. The toxic effects of formaldehyde on the nervous system.

    PubMed

    Songur, Ahmet; Ozen, Oguz Aslan; Sarsilmaz, Mustafa

    2010-01-01

    Formaldehyde (FA) is found in the polluted atmosphere of cities, domestic air (e.g., paint, insulating materials, chipboard and plywood, fabrics, furniture, paper), and cigarette smoke, etc.; therefore, everyone and particularly susceptible children may be exposed to FA. FA is also widely used in industrial and medical settings and as a sterilizing agent, disinfectant, and preservative. Therefore, employees may be highly exposed to it in there settings. Of particular concern to the authors are anatomists and medical students, who can be highly exposed to formaldehyde vapor during dissection sessions. Formaldehyde is toxic over a range of doses; chances of exposure and subsequent harmful effects are increased as (room) temperature increases, because of FA's volatility. Many studies have been conducted to evaluate the effects of FA during systemic and respiratory exposures in rats. This review compiles that literature and emphasizes the neurotoxic effects of FA on neuronal morphology, behavior, and biochemical parameters. The review includes the results of some of the authors' work related to FA neurotoxicity, and such neurotoxic effects from FA exposure were experimentally demonstrated. Moreover, the effectiveness of some antioxidants such as melatonin, fish omega-3, and CAPE was observed in the treatment of the harmful effects of FA. Despite the harmful effects from FA exposure, it is commonly used in Turkey and elsewhere in dissection laboratories. Consequently, all anatomists must know and understand the effects of this toxic agent on organisms and the environment, and take precautions to avoid unnecessary exposure. The reviewed studies have indicated that FA has neurotoxic characteristics and systemic toxic effects. It is hypothesized that inhalation of FA, during the early postnatal period, is linked to some neurological diseases that occur in adults. Although complete prevention is impossible for laboratory workers and members of industries utilizing FA

  4. Structure of SiAu16: can a silicon atom be stabilized in a gold cage?

    PubMed

    Sun, Qiang; Wang, Qian; Chen, Gang; Jena, Puru

    2007-12-01

    Nanostructures of Au and Si as well as Au-Si hybrid structures are topics of great current interest from both scientific and technological points of view. Recent discovery of Au clusters having fullerene-like geometries and the possibility of endohedral complexes with Si atoms inside the Au cage opens new possibilities for designing Au-Si nanostructures. Using ab initio simulated annealing method we have examined the stability of Si-Au16 endohedral complex. Contrary to what we believed, we find that the endohedral configuration is metastable and the structure where Si atom binds to the exterior surface of the Au16 cage is the lowest energy structure. The bonding of Si to Au cluster mimics its behavior of that in bulk and liquid phase of Au. In addition, doping of Si in high concentration would cause fracture and embrittlement in gold nanostructures just as it does in the bulk phase. Covalent bonding between Au-Au and Au-Si is found to be a dominant feature in the stability of the Au-Si nanostructures. Our study provides insight that may be useful in fabricating hybrid Au-Si nanostructures for applications microelectronics, catalysis, biomedicine, and jewelry industry. PMID:18067374

  5. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    NASA Astrophysics Data System (ADS)

    Katoch, Neha; Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G0 to 2G0 suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  6. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    SciTech Connect

    Ohno, S.; Shimakura, H.; Tahara, S.; Okada, T.

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  7. Health effects of urea formaldehyde foam insulation: evidence of causation.

    PubMed Central

    Norman, G R; Newhouse, M T

    1986-01-01

    Studies of health effects of urea formaldehyde foam insulation (UFFI) were critically reviewed by means of accepted rules for evidence of causation. Three categories of health effects were examined: reported symptoms, primarily of the upper respiratory tract, lower respiratory tract disease and cancer. Most of the studies purporting to demonstrate health effects of UFFI failed to meet minimal methodologic criteria for evidence of causation. Evidence from the adequate studies provides little support for the hypothesis of a causative role of UFFI in health problems. PMID:3512066

  8. New reactions of paraformaldehyde and formaldehyde with inorganic compounds

    NASA Technical Reports Server (NTRS)

    Becker, R. S.; Bercovici, T.; Hong, K.

    1974-01-01

    Both paraformaldehyde and formaldehyde undergo reactions in the presence of several inorganic compounds to generate a variety of interesting organic products that can be important in chemical evolutionary processes. Some examples are acrolein, acetaldehyde, methyl formate, methanol, glycolaldehyde and formic acid. The organic compounds are produced at temperatures as low as 56 C and in high yield (up to 75%). The quantity produced depends principally on the nature of the inorganic compound, the ratio of the inorganic compound to paraformaldehyde, temperature and reaction time. The percent distribution of product depends on some of the foregoing factors.

  9. Comparison of DNA damage by methylmelamines and formaldehyde

    SciTech Connect

    Ross, W.E.; McMillan, D.R.; Ross, C.F.

    1981-07-01

    The cytotoxicity and DNA damaging activity of S9-activated hexamethylmelamine (HMM) and pentamethylmelamine (PMM) were compared with suspected active metabolites in mouse leukemia L1210 cells. Following treatment of L1210 cells with high concentrations of activated HMM and PMM, there were no DNA single-strand breaks or interstrand cross-links observed by DNA alkaline elution and only a low frequency of DNA-protein cross-links. Formaldehyde (FA) at nonlethal concentrations caused far greater DNA-protein cross-linking. The cytotoxicities of HMM and PMM were found unlikely to be related to extracellular or intracellular release of FA.

  10. Oxidative decomposition of formaldehyde catalyzed by a bituminous coal

    SciTech Connect

    Haim Cohen; Uri Green

    2009-05-15

    It has been observed that molecular hydrogen is formed during long-term storage of bituminous coals via oxidative decomposition of formaldehyde by coal surface peroxides. This study has investigated the effects of coal quantity, temperature, and water content on the molecular hydrogen formation with a typical American coal (Pittsburgh No. 6). The results indicate that the coal's surface serves as a catalyst in the formation processes of molecular hydrogen. Furthermore, the results also indicate that low temperature emission of molecular hydrogen may possibly be the cause of unexplained explosions in confined spaces containing bituminous coals, for example, underground mines or ship holds. 20 refs., 4 figs., 6 tabs.

  11. Permeability and structure of resorcinol-formaldehyde gels

    SciTech Connect

    Scherer, G.W.; Alviso, C.; Pekala, R.; Gross, J.

    1996-12-31

    The permeability (D) of resorcinol-formaldehyde (RF) gels was measured using a beam-bending technique. For gels made at various solids contents and with different catalyst contents, the permeabilities ranged over a factor of {approximately} 50; the pore radii inferred from D varied from {approximately}3 to 30 nm. Pore radii obtained on RF aerogels using nitrogen desorption were severely affected by compression of the aerogel by capillary forces (resulting from the surface tension of liquid nitrogen). After correction for that effect, the desorption data were found to be in very good agreement with the pore sizes calculated from D.

  12. Interstellar cloud evolution and the abundance of formaldehyde

    NASA Technical Reports Server (NTRS)

    Langer, W. D.

    1976-01-01

    The time scale for essentially complete conversion of C(+) to CO in interstellar clouds can be comparable to, or greater than, dynamical time scales for evolution, therefore suggesting steady state time independent abundances to be inappropriate. The solutions for the time-dependent carbon chemistry in dense clouds, with density not less than 500/cu cm, indicate that significant amounts of neutral carbon will be present throughout a cloud's lifetime. These nonequilibrium values of C I can explain the relatively large abundances observed for formaldehyde, isotopes of carbon monoxide, and other trace molecules

  13. An infrared search for formaldehyde in several comets

    NASA Technical Reports Server (NTRS)

    Reuter, Dennis C.; Hoban, Susan; Mumma, Michael J.

    1992-01-01

    Models which assume either a parent or a distributed source for H2CO are presently used to retrieve 3-sigma upper limits to that species' production rate from a 3.55-3.64 micron search for cometary IR emission from the nu1 and nu5 bands of formaldehyde. A parent-source H2CO production rate relative to water of 0.15-0.80 percent is obtained, together with a distributed source production rate of 1.7-5.8 percent.

  14. Solid phase microextraction method development for measuring Henry's Law constants of formaldehyde in aqueous solutions

    EPA Science Inventory

    Formaldehyde (HCHO) has been of special concern as an indoor air pollutant because of its existence in a wide range of products and its adverse health effects. The air-water partitioning behavior of volatile organic compounds (VOCs) such as formaldehyde is an important process th...

  15. 40 CFR Appendix B to Subpart Nnn... - Free Formaldehyde Analysis of Insulation Resins by Hydroxylamine Hydrochloride

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Insulation Resins by Hydroxylamine Hydrochloride B Appendix B to Subpart NNN of Part 63 Protection of... NNN of Part 63—Free Formaldehyde Analysis of Insulation Resins by Hydroxylamine Hydrochloride 1. Scope... free-formaldehyde (FF) content such as insulation resins. It may also be suitable for other...

  16. 40 CFR 80.56 - Measurement methods for formaldehyde and acetaldehyde.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Measurement methods for formaldehyde and acetaldehyde. 80.56 Section 80.56 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.56 Measurement methods for formaldehyde...

  17. FORMALDEHYDE-INDUCED GENE EXPRESSION IN F344 RAT NASAL RESPIRATORY EPITHELIUM.

    EPA Science Inventory

    Formaldehyde-induced gene expression in F344 rat nasal respiratory epithelium

    ABSTRACT

    Formaldehyde, an occupational and environmental toxicant used extensively in the manufacturing of many household and personal use products, is known to induce squamous cell carci...

  18. Developing a Reference Material for Diffusion-Controlled Formaldehyde Emissions Testing

    EPA Science Inventory

    Emissions of formaldehyde from building materials can contaminate indoor air and create significant risks to human health. The need to control formaldehyde emissions from indoor materials is made more urgent by the prevailing drive to improve building energy by decreasing ventil...

  19. 40 CFR 721.10134 - Formaldehyde, polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Formaldehyde, polymer with... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10134 Formaldehyde, polymer..., polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (PMN P-05-1) is subject...

  20. 40 CFR 721.10134 - Formaldehyde, polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Formaldehyde, polymer with... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10134 Formaldehyde, polymer..., polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (PMN P-05-1) is subject...

  1. 40 CFR 721.10134 - Formaldehyde, polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Formaldehyde, polymer with... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10134 Formaldehyde, polymer..., polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (PMN P-05-1) is subject...

  2. 40 CFR 721.10358 - Formaldehyde reaction products with aryl amine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10358 Formaldehyde reaction products with aryl amine... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Formaldehyde reaction products...

  3. 40 CFR 721.10358 - Formaldehyde reaction products with aryl amine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10358 Formaldehyde reaction products with aryl amine... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Formaldehyde reaction products...

  4. 40 CFR 721.10358 - Formaldehyde reaction products with aryl amine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10358 Formaldehyde reaction products with aryl amine... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Formaldehyde reaction products...

  5. 40 CFR 80.56 - Measurement methods for formaldehyde and acetaldehyde.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and acetaldehyde. 80.56 Section 80.56 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Measurement methods for formaldehyde and acetaldehyde. (a) Formaldehyde and acetaldehyde will be measured by... acetaldehyde are used to determine the response, repeatability, and limit of quantitation of the HPLC...

  6. 40 CFR 721.3812 - Substituted phenols and formaldehyde polymer, alkylated (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... polymer, alkylated (generic). 721.3812 Section 721.3812 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3812 Substituted phenols and formaldehyde polymer... substance identified generically as substituted phenols and formaldehyde polymer, alkylated (PMN...

  7. 40 CFR 721.10134 - Formaldehyde, polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymer with... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10134 Formaldehyde, polymer..., polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (PMN P-05-1) is subject...

  8. 40 CFR 721.7046 - Formaldehyde, polymer with substituted phenols, glycidyl ether.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... phenols, glycidyl ether. 721.7046 Section 721.7046 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.7046 Formaldehyde, polymer with substituted phenols... substance identified as formaldehyde, polymer with substituted phenols, glycidyl ether (PMN P-93-955)...

  9. 40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted phenols (generic). 721.3810 Section 721.3810 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject...

  10. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  11. 40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted phenols (generic). 721.3810 Section 721.3810 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject...

  12. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  13. 40 CFR 721.7046 - Formaldehyde, polymer with substituted phenols, glycidyl ether.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... phenols, glycidyl ether. 721.7046 Section 721.7046 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.7046 Formaldehyde, polymer with substituted phenols... substance identified as formaldehyde, polymer with substituted phenols, glycidyl ether (PMN P-93-955)...

  14. 40 CFR 721.3810 - Formaldehyde, polymers with substituted phenols (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted phenols (generic). 721.3810 Section 721.3810 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3810 Formaldehyde, polymers with substituted phenols... identified generically as Formaldehyde, polymers with substituted phenols (PMN P-99-0558) is subject...

  15. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  16. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  17. 40 CFR 721.7046 - Formaldehyde, polymer with substituted phenols, glycidyl ether.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... phenols, glycidyl ether. 721.7046 Section 721.7046 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.7046 Formaldehyde, polymer with substituted phenols... substance identified as formaldehyde, polymer with substituted phenols, glycidyl ether (PMN P-93-955)...

  18. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  19. 40 CFR 721.10134 - Formaldehyde, polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymer with... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10134 Formaldehyde, polymer..., polymer with dialkylphenylamine, dialkylphenol and trimethylhexanediamine (PMN P-05-1) is subject...

  20. 40 CFR 721.3812 - Substituted phenols and formaldehyde polymer, alkylated (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... polymer, alkylated (generic). 721.3812 Section 721.3812 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3812 Substituted phenols and formaldehyde polymer... substance identified generically as substituted phenols and formaldehyde polymer, alkylated (PMN...