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Sample records for latex modified concrete

  1. Tensile Bond Strength of Latex-Modified Bonded Concrete Overlays

    NASA Astrophysics Data System (ADS)

    Dubois, Cameron; Ramseyer, Chris

    2010-10-01

    The tensile bond strength of bonded concrete overlays was tested using the in-situ pull-off method described in ASTM C 1583 with the goal of determining whether adding latex to the mix design increases bond strength. One slab of ductile concrete (f'c > 12,000 psi) was cast with one half tined, i.e. roughened, and one half steel-troweled, i.e. smooth. The slab surface was sectioned off and overlay mixtures containing different latex contents cast in each section. Partial cores were drilled perpendicular to the surface through the overlay into the substrate. A tensile loading device applied a direct tensile load to each specimen and the load was increased until failure occurred. The tensile bond strength was then calculated for comparison between the specimens.

  2. Investigation of modified asphalt concrete

    NASA Astrophysics Data System (ADS)

    Zimich, Vita

    2016-01-01

    Currently the problem of improving the asphalt quality is very urgent. It is used primarily as topcoats exposed to the greatest relative to the other layers of the road, dynamic load - impact and shear. The number of cars on the road, the speed of their movement, as well as the traffic intensity increase day by day. We have to upgrade motor roads, which entails a huge cost. World experience shows that the issue is urgent not only in Russia, but also in many countries in Europe, USA and Asia. Thus, the subject of research is the resistance of asphalt concrete to water and its influence on the strength of the material at different temperatures, and resistance of pavement to deformation. It is appropriate to search for new modifiers for asphaltic binder and mineral additives for asphalt mix to form in complex the skeleton of the future asphalt concrete, resistant to atmospheric condensation, soil characteristics of the road construction area, as well as the growing road transport load. The important task of the work is searching special modifying additives for bitumen binder and asphalt mixture as a whole, which will improve the quality of highways, increasing the period between repairs. The methods described in the normative-technical documentation were used for the research. The conducted research allowed reducing the frequency of road maintenance for 7 years, increasing it from 17 to 25 years.

  3. Latex-modified grouts for in-situ stabilization of buried transuranic/mixed waste

    SciTech Connect

    Allan, M.L.

    1996-06-01

    The Department of Applied Science at Brookhaven national Laboratory was requested to investigate latex-modified grouts for in-situ stabilization of buried TRU/mixed waste for INEL. The waste exists in shallow trenches that were backfilled with soil. The objective was to formulate latex-modified grouts for use with the jet grouting technique to enable in-situ stabilization of buried waste. The stabilized waste was either to be left in place or retrieved for further processing. Grouting prior to retrieval reduces the potential release of contaminants. Rheological properties of latex-modified grouts were investigated and compared with those of conventional neat cement grouts used for jet grouting.

  4. Cellulose fibers modified with nano-sized antimicrobial polymer latex for pathogen deactivation.

    PubMed

    Pan, Yuanfeng; Xiao, Huining; Cai, Pingxiong; Colpitts, Meaghan

    2016-01-01

    Antimicrobial cellulose fibers and paper products are of great importance for various applications. In this work, novel core-shell antimicrobial latexes based on hydrophobic acrylate monomers and antimicrobial macromonomer (GPHGH) were successfully prepared via a seeded semi-continuous emulsion copolymerization in the presence of a cationic surfactant. The surface properties as well as size of latex were tailored by varying the amount of GPHGH incorporated during the copolymerization. The resulting cationic nano-sized latexes showed the strong adsorption and formed monolayer on the surfaces of bleached sulfite fibers, thus rendering the cellulose fibers antimicrobial. An excellent antimicrobial activity (>99.99% inhibition) of modified fiber toward Escherichia coli was achieved at 0.3wt% of latex dosage (on dry fibers). Results of transmission electron microscopy (TEM) observation confirmed that the particles obtained indeed possessed a desired core-shell structure. The latexes themselves exhibited high antimicrobial activities against E. coli with the minimum inhibitory concentration (MIC) as low as 6.25ppm (similar to that of pure guanidine-based polymer). Moreover, the mechanical strength of the hand-sheets made from latex-modified cellulose fibers was also improved due to the filming of the latex on fiber surfaces.

  5. Solid state NMR and LVSEM studies on the hardening of latex modified tile mortar systems

    SciTech Connect

    Rottstegge, J.; Arnold, M.; Herschke, L.; Glasser, G.; Wilhelm, M.; Spiess, H.W. . E-mail: spiess@mpip-mainz.mpg.de; Hergeth, W.D.

    2005-12-15

    Construction mortars contain a broad variety of both inorganic and organic additives beside the cement powder. Here we present a study of tile mortar systems based on portland cement, quartz, methyl cellulose and different latex additives. As known, the methyl cellulose stabilizes the freshly prepared cement paste, the latex additive enhances final hydrophobicity, flexibility and adhesion. Measurements were performed by solid state nuclear magnetic resonance (NMR) and low voltage scanning electron microscopy (LVSEM) to probe the influence of the latex additives on the hydration, hardening and the final tile mortar properties. While solid state NMR enables monitoring of the bulk composition, scanning electron microscopy affords visualization of particles and textures with respect to their shape and the distribution of the different phases. Within the alkaline cement paste, the poly(vinyl acetate) (VAc)-based latex dispersions stabilized by poly(vinyl alcohol) (PVA) were found to be relatively stable against hydrolysis. The influence of the combined organic additives methyl cellulose, poly(vinyl alcohol) and latexes stabilized by poly(vinyl alcohol) on the final silicate structure of the cement hydration products is small. But even small amounts of additives result in an increased ratio of ettringite to monosulfate within the final hydrated tile mortar as monitored by {sup 27}Al NMR. The latex was found to be adsorbed to the inorganic surfaces, acting as glue to the inorganic components. For similar latex water interfaces built up by poly(vinyl alcohol), a variation in the latex polymer composition results in modified organic textures. In addition to the networks of the inorganic cement and of the latex, there is a weak network build up by thin polymer fibers, most probably originating from poly(vinyl alcohol). Besides the weak network, polymer fibers form well-ordered textures covering inorganic crystals such as portlandite.

  6. Fabrication of latex rubber reinforced with micellar nanoparticle as an interface modifier

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reinforced latex rubbers were fabricated by incorporating small amount of nanoparticles as interface modifier. The rubbers were fabricated in a compression mold at 130°C. The incorporated nanoparticles were prepared from wheat protein (gliadin) and ethyl cyanoacrylate (ECA). These nanoparticles were...

  7. Research on the chemical mechanism in the polyacrylate latex modified cement system

    SciTech Connect

    Wang, Min; Wang, Rumin; Zheng, Shuirong; Farhan, Shameel; Yao, Hao; Jiang, Hao

    2015-10-15

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH){sub 2} (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH){sub 2}.

  8. Synthesis of polymer latex particles decorated with organically-modified laponite clay platelets via emulsion polymerization.

    PubMed

    Herrera, Norma Negrete; Persoz, Stéphanie; Putaux, Jean-Luc; David, Laurent; Bourgeat-Lami, Elodie

    2006-02-01

    We report a new route to colloidal nanocomposites consisting of polymer latex particles covered with Laponite clay nanoplatelets. These composite particles are prepared by seeded emulsion (co)polymerization of styrene and butyl acrylate from Laponite clay suspensions previously functionalized by ion exchange using either a free radical initiator: 2,2-azobis (2-methylpropionamidine) hydrochloride (AIBA) or a cationic vinyl monomer: 2-(methacryloyloxy) ethyl trimethyl ammonium chloride (MADQUAT). The successful intercalation of the cationic reactive molecules was confirmed by elemental analysis, FTIR, 13C solid-state NMR and WAXD. The organically-modified clays were dispersed into water with the help of tetrasodium pyrophosphate and an anionic surfactant. stable latexes, produced under different experimental conditions, were successfully obtained from the clay suspensions. Cryo-TEM images of the resulting latexes showed spherical composite particles with diameters in the 50-250 nm range with clay sheets located on their surface. This paper reports on the effect of the processing conditions on the particle morphology and latex stability, and describes the mechanism of formation of the nanocomposite particles.

  9. Latex Allergy

    MedlinePlus

    ... a milky fluid that comes from the tropical rubber tree. Hundreds of everyday products contain latex. Repeated ... latex. Common latex products include Gloves Condoms Balloons Rubber bands Shoe soles Pacifiers You can find latex- ...

  10. Latex allergy.

    PubMed

    Pollart, Susan M; Warniment, Christa; Mori, Takahiro

    2009-12-15

    The prevalence of latex allergy in the general population is low; however, the risk of developing latex allergy is higher in persons with increased latex exposure, such as health care workers or persons who work in the rubber industry. Children with spina bifida and others who undergo multiple surgeries or procedures, particularly within the first year of life, are also at greater risk of latex allergy. Reactions to latex allergy can range from type IV delayed hypersensitivity (e.g., contact dermatitis) to type I immediate hypersensitivity (e.g., urticaria, bronchospasm, anaphylaxis). Latex allergy can be diagnosed with clinical history, skin prick testing, latex-specific serum immunoglobulin E testing, and glove provocation testing. The main goals of latex allergy management are avoidance of exposure to latex allergens and appropriate treatment of allergic reactions. The use of nonlatex products from birth may prevent potentially serious allergic reactions. Widespread adoption of nonlatex or low-latex gloves has decreased the incidence of latex sensitization in health care workers. PMID:20000303

  11. Latex protein: a hidden "food" allergen?

    PubMed

    Beezhold, D H; Reschke, J E; Allen, J H; Kostyal, D A; Sussman, G L

    2000-01-01

    Avoidance of latex allergens is the primary method to prevent adverse reactions. Natural rubber latex is found in many different products in both the health care industry and in modern society, and consequently results in unexpected exposures of sensitized individuals. The use of latex gloves by food handlers provides one potential route for inadvertent exposure to latex allergens. In this study we have used two immunological methods to determine whether latex proteins are transferred to foods following contact with latex gloves. Direct transfer of latex protein to cheese was visualized using a modified immunoblot method. Sliced cheese was touched with a gloved finger. A nitrocellulose membrane was applied to lift the potential fingerprints and a rabbit anti-latex antiserum was used to visualize the transfer of any latex finger-prints. After handling lettuce with gloves, transferred protein was recovered by extracting the lettuce and quantified using an inhibition ELISA for latex proteins. Fingerprints of latex protein were readily detectable on cheese after contact with powdered latex gloves, but not with vinyl gloves. Furthermore, powdered latex glove use resulted in measurable amounts of latex protein on lettuce with an exposure-dependent increase in the latex protein levels. Lettuce alone or lettuce handled with vinyl gloves was negative for latex protein. The use of latex gloves by food handlers is the source of an indirect food additive in the form of latex proteins. It is recommended that food handlers avoid the use of latex gloves to eliminate inadvertent exposure of latex-sensitive individuals. PMID:11061040

  12. Crumb rubber modified asphalt concrete in Oregon. Summary report. Report for 1985-94

    SciTech Connect

    Hunt, E.; Peters, W.

    1995-07-01

    Over the last nine years, the Oregon Department of Transportation (ODOT) has constructed 13 projects using crumb rubber modifiers (CRM) in asphalt concrete pavements using both the wet and dry process. State and federal legislation may require the use of recycled rubber in asphalt concrete, therefore, the Oregon Department of Transportation is interested in determining the most cost -effective crumb rubber modified asphalt concrete. The report includes a literature review on the use of crumb rubber modifiers in asphalt concrete pavement; a review on non-ODOT CRM paving projects constructed by Oregon counties and cities; and the Washington Department of Transportation. In additon, the report summarizes the data collected on all CRM hot mix asphalt concrete pavement projects constructed by ODOT. The ODOT information includes background constitution, cost, and performance data for each of the test and control sections. Finally, the future activities of the project are reviewed.

  13. A comparison of flexural strengths of polymer (SBR and PVA) modified, roller compacted concrete

    PubMed Central

    Karadelis, John N.; Lin, Yougui

    2015-01-01

    This brief article aims to reveal the flexural performance, including the equivalent flexural strength of PVA (Polyvinyl Alcohol) modified concrete by comparing it primarily with that of SBR (Styrene Butadiene Rubber) concrete. This data article is directly related to Karadelis and Lin [6]. PMID:26306313

  14. Morphological and biodegradability studies of Euphorbia latex modified polyester - Banana fiber composites

    NASA Astrophysics Data System (ADS)

    Rai, Bhuvneshwar; Kumar, Gulshan; Diwan, R. K.

    2016-05-01

    The composites of Banana fiber were prepared using polyester resin blended Euphorbia coagulum, morphology and the degree of rate of aerobic biodegradation of the prepared composites were studied. Polyester resin blended Euphorbia coagulum containing Banana fiber, Euphorbia coagulum and polyester resin taken in the ratio 40: 24: 36 was used for the study, which was the optimum composition of the composite reported in a previous study by the authors. In the biodegradability study cellulose has been used as positive reference material. Result shows that Euphorbia coagulum modified polyester - Banana fiber composites exhibited biodegradation to the extent of around 40%. The use of developed green composites may help in reducing the generation of non-biodegradable polymeric wastes.

  15. Transport and attenuation of carboxylate-modified latex microspheres in fractured rock laboratory and field tracer tests

    USGS Publications Warehouse

    Becker, M.W.; Reimus, P.W.; Vilks, P.

    1999-01-01

    Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks of pathogen contamination in drinking water wells. Much has been learned through laboratory and field-scale colloid tracer tests, but progress has been hampered by a lack of consistent tracer testing methodology at different scales and fluid velocities. This paper presents laboratory and field tracer tests in fractured rock that use the same type of colloid tracer over an almost three orders-of-magnitude range in scale and fluid velocity. Fluorescently-dyed carboxylate-modified latex (CML) microspheres (0.19 to 0.98 ??m diameter) were used as tracers in (1) a naturally fractured tuff sample, (2) a large block of naturally fractured granite, (3) a fractured granite field site, and (4) another fractured granite/schist field site. In all cases, the mean transport time of the microspheres was shorter than the solutes, regardless of detection limit. In all but the smallest scale test, only a fraction of the injected microsphere mass was recovered, with the smaller microspheres being recovered to a greater extent than the larger microspheres. Using existing theory, we hypothesize that the observed microsphere early arrival was due to volume exclusion and attenuation was due to aggregation and/or settling during transport. In most tests, microspheres were detected using flow cytometry, which proved to be an excellent method of analysis. CML microspheres appear to be useful tracers for fractured rock in forced gradient and short-term natural gradient tests, but longer residence times may result in small microsphere recoveries.Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks

  16. [Latex allergy].

    PubMed

    Bayrou, Olivier

    2006-02-15

    Immediate hypersensitivity to natural rubber latex has increased since the early 1980s. High prevalence of latex sensitization and allergy are observed among healthcare workers, atopic individuals and children who had undergone multiple surgical operations (spina bifida, congenital anomalies). Presenting symptoms are polymorphous: contact urticaria, rhinitis, conjunctivitis, asthma, and anaphylaxis. Corn-starch-latex particles released in the air after powdered gloves manipulation may be inhaled and lead to occupational asthma. The diagnosis may be made by a focused clinical history, prick-test, detection of specific IgE antibody and challenge test. Almost half of patients allergic to natural rubber latex show an associated fruit allergy: avocado, banana, kiwi, chestnut. Most of cutaneous delayed reactions (eczema) to rubber are caused by rubber additives (accelerators of vulcanization, anti-oxidants). PMID:16583955

  17. [Latex allergy].

    PubMed

    Richter, J; Susický, P

    2000-04-01

    The authors describe a case of an allergic affection in a patient with occupational exposure to latex allergens with a history of anaphylactic reaction to poppy seed and reaction to the antigens of apples, oranges, tangerines, peanuts and bananas, revealed by the method CAP Phadiatop. A marked reaction was initiated after the use of a shampoo containing volatile banana oil. The authors emphasize the high incidence of latex allergy, the manifestations of which may be encountered also in clinical ophthalmology. PMID:10874793

  18. Influence of association of "EVA-NBR" on indirect tensile strength of modified bituminous concrete

    NASA Astrophysics Data System (ADS)

    Chinoun, M.; Soudani, K.; Haddadi, S.

    2016-04-01

    The aim of this work is to contribute to the improvement of the mechanical properties of bituminous concrete by modification of bituminous concrete. In this study, we present the results of the indirect tensile strength "ITS" of modified bituminous concrete by the combination of two modifiers, one is a plastomer EVA (Ethylene Vinyl Acetate) and the other is a industrial waste from the shoe soles grinding NBR (Nitrile Butadiene Rubber) as crumb rubber. To modify the bitumen a wet process was used. The results show that the modification of bitumen by EVA-NBR combination increases their resistance to the indirect traction "ITS" compared to the bituminous concrete control. The mixture of 5% [50% EVA+ 50% NBR] is given the best result among the other associations.

  19. UseLATEX.cmake

    SciTech Connect

    Moreland, Kenneth

    2015-10-20

    UseLATEX.cmake is a collection of script functions and examples for building LaTeX documents. It simplifies the process of building LaTeX documents, which requires the execution of multiple programs and the management of several input files. UseLATEX.cmake also provides several options to customize the LaTeX build process.

  20. Latex allergy: an emerging problem in health care.

    PubMed

    Kinnaird, S W; McClure, N; Wilham, S

    1995-10-01

    Allergy to latex has been increasing as the use of latex products has grown. The increase is disproportionately occurring in those people with myelodysplasias, those who have undergone multiple surgical procedures, and health care providers. Within those groups, the most susceptible to latex allergy are people with other allergies. Early identification of high-risk individuals and their avoidance of products containing latex can minimize the occurrence of this allergic response. Heightened awareness among health care providers is needed because latex is very common in hospitals and clinics. Inadvertent exposure places latex-sensitive individuals in danger of anaphylaxis. Nurses caring for infants and children are able to modify the environment of those at risk for latex allergy, reducing exposure to this potentially dangerous substance. Teaching families of children at risk will help them avoid latex in the home; many common household substances contain latex and are likely to trigger allergic responses. PMID:7565525

  1. Improvement of reinforced concrete properties based on modified starch/polybutadiene nanocomposites.

    PubMed

    Saboktakin, Amin; Saboktakin, Mohammad Reza

    2014-09-01

    A novel polymer-modified cement concrete with carboxymethyl starch (CMS) and 1,4-cis polybutadiene (PBD) system by mixing polymer dispersions or redispersible polymer powders with the fresh mixture have been examined. In this paper, the addition of CMS-PBD powders in an aqueous solution is studied. Polymeric molecules are supplied on a molecular scale, improving the approach of the relatively large cement grains by the polymers. The chemical and mechanical properties of CMS-PBD-modified cement concrete have been studied. The additions of very small amounts of CMS-PBD polymeric system results in an improvement of the durability and the adhesion strength of the cementitious materials, which makes them appropriate as repair materials. PMID:25036606

  2. Improvement of reinforced concrete properties based on modified starch/polybutadiene nanocomposites.

    PubMed

    Saboktakin, Amin; Saboktakin, Mohammad Reza

    2014-09-01

    A novel polymer-modified cement concrete with carboxymethyl starch (CMS) and 1,4-cis polybutadiene (PBD) system by mixing polymer dispersions or redispersible polymer powders with the fresh mixture have been examined. In this paper, the addition of CMS-PBD powders in an aqueous solution is studied. Polymeric molecules are supplied on a molecular scale, improving the approach of the relatively large cement grains by the polymers. The chemical and mechanical properties of CMS-PBD-modified cement concrete have been studied. The additions of very small amounts of CMS-PBD polymeric system results in an improvement of the durability and the adhesion strength of the cementitious materials, which makes them appropriate as repair materials.

  3. Modified-sulfur cements for use in concretes, flexible pavings, coatings, and grouts

    NASA Astrophysics Data System (ADS)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1981-05-01

    A family of modified-sulfur cements was developed for the preparation of construction materials with improved properties. Various types of sulfur cements were prepared by reacting sulfur with mixtures of dicyclopentadiene and oligomers of cyclopentadiene. Durable cements were prepared with structural characteristics ranging from rigid to flexible. These cements were used to prepare corrosion-resistant materials for use in a wide variety of industrial applications where resistance to acidic and salt conditions is needed. These materials were prepared as rigid concretes, flexible pavings, spray coatings, and grouts. Production of modified-sulfur cements in a commercial-size plant was demonstrated.

  4. Latex allergies - for hospital patients

    MedlinePlus

    ... hospital; Contact dermatitis - latex allergy; Allergy - latex; Allergic reaction - latex ... You can have a reaction to latex if your skin, mucous membranes (eyes, mouth, or other moist areas), or bloodstream (during surgery) come into contact ...

  5. Durability of crystalline phase in concrete microstructure modified by the mineral powders: evaluation by nanoindentation tests

    NASA Astrophysics Data System (ADS)

    Rajczakowska, Magdalena; Łydżba, Dariusz

    2016-03-01

    This paper presents the nanoindentation investigation of the evolution of concrete microstructure modified by the Internal Crystallization Technology mineral powders. The samples under study were retrieved from a fragment of a circular concrete lining of the vertical mine shaft at a depth of approximately 1,000 m. Due to the aggressive environment and exposure to contaminated water, the internal surface of the structure was deteriorated, decreasing its strength significantly. The mineral powders were applied directly on the surface lining. The specimens were investigated one month, three months and one year after the application of the aforementioned substance in order to verify the time dependence of the strengthening processes and durability of the crystalline phase. The microstructural changes of concrete were assessed with the use of nanoindentation technique. The testing procedure involved including the previously cut specimens in the epoxy resin and grinding and polishing in order to reduce the surface roughness. As a result of the nanoindentation tests the hardness as well as Young's modulus of the material were evaluated. The results were then compared and statistically analyzed. As a consequence, the disintegration time of the crystalline network in the pores of concrete was identified.

  6. Balanced improvement of high performance concrete material properties with modified graphite nanomaterials

    NASA Astrophysics Data System (ADS)

    Peyvandi, Amirpasha

    Graphite nanomaterials offer distinct features for effective reinforcement of cementitious matrices in the pre-crack and post-crack ranges of behavior. Thoroughly dispersed and well-bonded nanomaterials provide for effective control of the size and propagation of defects (microcracks) in matrix, and also act as closely spaced barriers against diffusion of moisture and aggressive solutions into concrete. Modified graphite nanomaterials can play multi-faceted roles towards enhancing the mechanical, physical and functional attributes of concrete materials. Graphite nanoplatelets (GP) and carbon nanofibers (CNF) were chosen for use in cementitious materials. Experimental results highlighted the balanced gains in diverse engineering properties of high-performance concrete realized by introduction of graphite nanomaterials. Nuclear Magnetic Resonance (NMR) spectroscopy was used in order to gain further insight into the effects of nanomaterials on the hydration process and structure of cement hydrates. NMR exploits the magnetic properties of certain atomic nuclei, and the sensitivity of these properties to local environments to generate data which enables determination of the internal structure, reaction state, and chemical environment of molecules and bulk materials. 27 Al and 29Si NMR spectroscopy techniques were employed in order to evaluate the effects of graphite nanoplatelets on the structure of cement hydrates, and their resistance to alkali-silica reaction (ASR), chloride ion diffusion, and sulfate attack. Results of 29Si NMR spectroscopy indicated that the percent condensation of C-S-H in cementitious paste was lowered in the presence of nanoplatelets at the same age. The extent of chloride diffusion was assessed indirectly by detecting Friedel's salt as a reaction product of chloride ions with aluminum-bearing cement hydrates. Graphite nanoplatelets were found to significantly reduce the concentration of Friedel's salt at different depths after various periods

  7. Evaluation of biopolymer-modified concrete systems for disposal of cathode ray tube glass.

    PubMed

    Kim, Daeik; Petrisor, loana G; Yen, Teh Fu

    2005-07-01

    Cathode ray tubes (CRTs) from computer monitors and television sets, which contain significantly high percentage of lead (Pb) by weight, represent an enormous and growing hazardous waste problem in the United States and worldwide. As a result, new technologies are needed to cope with current CRT waste stream and increased hazard and build new markets for its recycled components, developing commercially viable concrete composites, as well as minimizing CRT disposal problems. In this study, commercially available biopolymers, such as xanthan gum, guar gum, and chitosan, were used to encapsulate CRT glass waste, reducing the Pb leachability. The biopolymers utilized contain a number of useful functional groups, such as carboxyl (xanthan), hydroxyl (guar), and amino groups (chitosan), which play important roles in binding and stabilizing Pb onto concrete structures. The use of biopolymers in concrete systems can create a stable interpenetrating cross-linking composite that will last for many years. Results from these new composites show 30% higher compressive strength than standard concrete and a sharp decrease in lead leachability from several thousand milligrams per liter initially to an amount of three-tenths milligrams per liter or lower values (much lower than the U.S. Environment Protection Agency standard for hazardous waste of 5 mg/L by the toxicity characteristic leaching procedure test), and for some of the composites leachability is below even the standard for drinking water. This efficient and cost-effective CRT-biopolymer-concrete composite is a new class of biopolymer-modified material that can potentially perform a significant role in relieving the current CRT issue.

  8. LATEX for Librarians.

    ERIC Educational Resources Information Center

    Boatright, George S.

    This paper presents the basics of "LATEX," a computerized typesetting program popular with mathematicians and other writers of technical papers, and compares it to conventional word processing programs. LATEX, which requires a text editor such as WordPad or NotePad--the text editor is used to produce and input file which the LATEX program…

  9. Managing latex allergies at home

    MedlinePlus

    ... problems. Latex is made from the sap of rubber trees. It is very strong and stretchy. So ... may contain latex include: Balloons Condoms and diaphragms Rubber bands Shoe soles Bandages Latex gloves Toys Paint ...

  10. Natural rubber latex allergy.

    PubMed

    Deval, Ravi; Ramesh, V; Prasad, G B K S; Jain, Arun Kumar

    2008-01-01

    Natural rubber latex (NRL) is a ubiquitous allergen as it is a component of > 40,000 products in everyday life. Latex allergy might be attributed to skin contact or inhalation of latex particles. Latex allergy is an IgE-mediated hypersensitivity to NRL, presenting a wide range of clinical symptoms such as angioedema, swelling, cough, asthma, and anaphylactic reactions. Until 1979, latex allergy appeared only as type IV delayed hypersensitivity; subsequently, the proportion of different allergy types drifted towards type IV contact allergy reactions. Several risk factors for sensitization to NRL are already known and well documented. Some authors have established a positive correlation between a history of multiple surgical interventions, atopy, spina bifida malformation, and latex allergy incidence. We suspect an increase in latex allergy incidence in association with increased atopy and sensitivity to environmental allergens in the industrial population. It is often postulated in literature that the groups of workers at risk for this allergy are essentially workers in the latex industry and healthcare professionals. In this population, direct internal and mucosal contact with NRL medical devices may be the route of sensitization as factors such as the number of procedures and use of NRL materials (catheters and tubes) were associated with increased risk of latex sensitization and allergy. PMID:18797048

  11. Application of modified-alginate encapsulated carbonate producing bacteria in concrete: a promising strategy for crack self-healing

    PubMed Central

    Wang, Jianyun; Mignon, Arn; Snoeck, Didier; Wiktor, Virginie; Van Vliergerghe, Sandra; Boon, Nico; De Belie, Nele

    2015-01-01

    Self-healing concrete holds promising benefits to reduce the cost for concrete maintenance and repair as cracks are autonomously repaired without any human intervention. In this study, the application of a carbonate precipitating bacterium Bacillus sphaericus was explored. Regarding the harsh condition in concrete, B. sphaericus spores were first encapsulated into a modified-alginate based hydrogel (AM-H) which was proven to have a good compatibility with the bacteria and concrete regarding the influence on bacterial viability and concrete strength. Experimental results show that the spores were still viable after encapsulation. Encapsulated spores can precipitate a large amount of CaCO3 in/on the hydrogel matrix (around 70% by weight). Encapsulated B. sphaericus spores were added into mortar specimens and bacterial in situ activity was demonstrated by the oxygen consumption on the mimicked crack surface. While specimens with free spores added showed no oxygen consumption. This indicates the efficient protection of the hydrogel for spores in concrete. To conclude, the AM-H encapsulated carbonate precipitating bacteria have great potential to be used for crack self-healing in concrete applications. PMID:26528254

  12. Application of modified-alginate encapsulated carbonate producing bacteria in concrete: a promising strategy for crack self-healing.

    PubMed

    Wang, Jianyun; Mignon, Arn; Snoeck, Didier; Wiktor, Virginie; Van Vliergerghe, Sandra; Boon, Nico; De Belie, Nele

    2015-01-01

    Self-healing concrete holds promising benefits to reduce the cost for concrete maintenance and repair as cracks are autonomously repaired without any human intervention. In this study, the application of a carbonate precipitating bacterium Bacillus sphaericus was explored. Regarding the harsh condition in concrete, B. sphaericus spores were first encapsulated into a modified-alginate based hydrogel (AM-H) which was proven to have a good compatibility with the bacteria and concrete regarding the influence on bacterial viability and concrete strength. Experimental results show that the spores were still viable after encapsulation. Encapsulated spores can precipitate a large amount of CaCO3 in/on the hydrogel matrix (around 70% by weight). Encapsulated B. sphaericus spores were added into mortar specimens and bacterial in situ activity was demonstrated by the oxygen consumption on the mimicked crack surface. While specimens with free spores added showed no oxygen consumption. This indicates the efficient protection of the hydrogel for spores in concrete. To conclude, the AM-H encapsulated carbonate precipitating bacteria have great potential to be used for crack self-healing in concrete applications.

  13. Latex in the Hospital Environment

    MedlinePlus

    LATEX in the Hospital Environment Updated Fall 2015 This list provides a guide to some of the most common objects containing latex and offers some ... remover–Sepha Pharm) 1 LATEX in the Hospital Environment (continued) Frequently contains LATEX OR/Infection Control masks, ...

  14. 40 CFR 428.100 - Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... latex-dipped, latex-extruded, and latex-molded rubber subcategory. 428.100 Section 428.100 Protection of... POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory § 428.100 Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory....

  15. 40 CFR 428.100 - Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... latex-dipped, latex-extruded, and latex-molded rubber subcategory. 428.100 Section 428.100 Protection of... POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory § 428.100 Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory....

  16. Latex Allergy: A Prevention Guide

    MedlinePlus

    ... chemicals added to latex during harvesting, processing, or manufacturing. These chemicals can cause a skin rash similar ... allergy. However, they may reduce reactions to chemical additives in the latex (allergic contact dermatitis). Use appropriate ...

  17. Latex samples for RAMSES electrophoresis experiment on IML 2

    NASA Technical Reports Server (NTRS)

    Seaman, Geoffrey V. F.; Knox, Robert J.

    1994-01-01

    The objectives of these reported studies were to provide ground based support services for the flight experiment team for the RAMSES experiment to be flown aboard IML-2. The specific areas of support included consultation on the performance of particle based electrophoresis studies, development of methods for the preparation of suitable samples for the flight hardware, the screening of particles to obtain suitable candidates for the flight experiment, and the electrophoretic characterization of sample particle preparations. The first phases of these studies were performed under this contract, while the follow on work was performed under grant number NAG8 1081, 'Preparation and Characterization of Latex Samples for RAMSES Experiment on IML 2.' During this first phase of the experiment the following benchmarks were achieved: Methods were tested for the concentration and resuspension of latex samples in the greater than 0.4 micron diameter range to provide moderately high solids content samples free of particle aggregation which interferred with the normal functioning of the RAMSES hardware. Various candidate latex preparations were screened and two candidate types of latex were identified for use in the flight experiments, carboxylate modified latex (CML) and acrylic acid-acrylamide modified latex (AAM). These latexes have relatively hydrophilic surfaces, are not prone to aggregate, and display sufficiently low electrophoretic mobilities in the flight buffer so that they can be used to make mixtures to test the resolving power of the flight hardware.

  18. Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

    PubMed

    Chen, Jun; Poon, Chi-Sun

    2009-08-01

    Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing. PMID:19540649

  19. Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

    PubMed

    Chen, Jun; Poon, Chi-Sun

    2009-08-01

    Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing.

  20. Use of recycled chunk rubber asphalt concrete (CRAC) on low volume roads and use of recycled crumb rubber modifier in asphalt pavements. Final report, June 1993-June 1995

    SciTech Connect

    Hossain, M.; Funk, L.P.; Sadeq, M.A.; Marucci, G.

    1995-06-01

    The major objective of this project was to formulate a Chunk Rubber Asphalt Concrete (CRAC) mix for use on low volume roads. CRAC is a rubber modified asphalt concrete product produced by the `dry process` where rubber chunks of 1/2 inch size are used as aggregate in a cold mix with a type C fly ash. The second objective of this project was to develop guidelines concerning the use of rubber modified asphalt concrete hot mix to include: (1) Design methods for use of asphalt-rubber mix for new construction and overlay, (2) Mix design method for asphalt-rubber, and (3) Test method for determining the amount of rubber in an asphalt-rubber concrete for quality control purposes.

  1. Excitation energy transfer between erythrosin B and malachite green adsorbed on a microheterogeneous polymer latex

    NASA Astrophysics Data System (ADS)

    Dutta, A. K.

    1995-07-01

    In this article electronic excitation energy transfer between the aggregates of the donor erythrosin B (EB) and the acceptor malachite green (MG) has been studied in polystyrenebutylmethacrylate latex. Steady state flourescence quenching studies reveal that with the increasing latex concentration the rate of quenching decreases initially, attains a minimum and then increases again. Such a behaviour has been attributed to aggregation of the dye molecules at low latex concentration and redistribution at larger latex concentrations. These results illustrate the role of the microenvironment in modifying the energy transfer reaction rates and provides a model system for understanding energy transfer mechanisms in context to photosynthesis in real living systems.

  2. Quantitation of latex allergens.

    PubMed

    Palosuo, Timo; Alenius, Harri; Turjanmaa, Kristiina

    2002-05-01

    Minimizing allergen concentration in latex goods to prevent sensitization to natural rubber latex (NRL) and thereby the development of clinical allergy is acknowledged as of mutual interest for rubber manufacturers and regulatory health authorities. However, measuring total protein, the principal currently available method, cannot be deemed a satisfactory regulatory measure to control allergen content. Specific methods based on human IgE-containing reagents, such as radioallergosorbent test (RAST) inhibition, have been available in certain laboratories for demonstrating NRL allergens in rubber products but the methods lack standardization. Currently, one commercial test has become available for measuring individual NRL allergens by capture ELISA-based assays using monoclonal antibodies and purified or recombinant allergens. Such methods are specific, they can be properly standardized, and they are of sufficient sensitivity and reproducibility. Results from medical gloves collected in two national market surveys in Finland in 1995 and 1999, respectively, show that Hev b 6.02 and Hev b 5, the two major allergens for NRL-allergic adults, are the most abundant allergens regularly detectable in high- and moderate-allergen gloves. In addition, Hev b 3 and Hev b 1, the two major allergens for children with spina bifida, are also commonly found. In general, when the sum of the four allergens exceeded 1 microg/g, most NRL-allergic patients showed positive skin prick test reactions against them. Using these new methods assessment of threshold levels that could in due course become guidelines for the rubber industry and regulatory health authorities is becoming possible. Eventually, this progress is expected to lead to a declining incidence of latex allergy. PMID:12079417

  3. Nano-modified cement composites and its applicability as concrete repair material

    NASA Astrophysics Data System (ADS)

    Manzur, Tanvir

    Nanotechnology or Nano-science, considered the forth industrial revolution, has received considerable attention in the past decade. The physical properties of a nano-scaled material are entirely different than that of bulk materials. With the emerging nanotechnology, one can build material block atom by atom. Therefore, through nanotechnology it is possible to enhance and control the physical properties of materials to a great extent. Composites such as concrete materials have very high strength and Young's modulus but relatively low toughness and ductility due to their covalent bonding between atoms and lacking of slip systems in the crystal structures. However, the strength and life of concrete structures are determined by the microstructure and mass transfer at nano scale. Cementitious composites are amenable to manipulation through nanotechnology due to the physical behavior and size of hydration products. Carbon nanotubes (CNT) are nearly ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. So there is a great potential to utilize CNT in producing new cement based composite materials. It is evident from the review of past literature that mechanical properties of nanotubes reinforced cementitious composites have been highly variable. Some researches yielded improvement in performance of CNT-cement composites as compared to plain cement samples, while other resulted in inconsequential changes in mechanical properties. Even in some cases considerable less strengths and modulus were obtained. Another major difficulty of producing CNT reinforced cementitious composites is the attainment of homogeneous dispersion of nanotubes into cement but no standard procedures to mix CNT within the cement is available. CNT attract more water to adhere to their surface due to their high aspect ratio which eventually results in less workability of the cement mix. Therefore, it is extremely important to develop a suitable mixing technique and an

  4. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    NASA Astrophysics Data System (ADS)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  5. 40 CFR 428.100 - Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... latex-dipped, latex-extruded, and latex-molded rubber subcategory. 428.100 Section 428.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory §...

  6. 40 CFR 428.100 - Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... latex-dipped, latex-extruded, and latex-molded rubber subcategory. 428.100 Section 428.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory §...

  7. 40 CFR 428.100 - Applicability; description of the latex-dipped, latex-extruded, and latex-molded rubber subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... latex-dipped, latex-extruded, and latex-molded rubber subcategory. 428.100 Section 428.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory §...

  8. Review of crumb-rubber modified asphalt concrete technology. Final research report

    SciTech Connect

    Papagiannakis, A.T.; Lougheed, T.J.

    1995-11-01

    This study presents an analysis of the characteristics of crumb-rubber modified (CRM) asphalt pavements. It is comprised of a state-of-the-art literature review and laboratory testing conducted with a Brookfield viscometer. The reaction that occurs between the rubber and asphalt is not a chemical reaction, but rather a diffusion process that includes the physical absorption of aromatic oils from the asphalt into the polymer chain of the rubber. The presence of CRM in asphalt produces a thicker binder, which increases aging and oxidation resistance. The presence of carbon black in CRM improves binder durability. The temperature susceptibility of the mix is reduced, causing more uniform fatigue characteristics. CRM applications have been met with various degrees of success because existing quality control and quality assurance methods have not been developed enough to ensure desired binder properties in the field.

  9. [History of "L" as in latex].

    PubMed

    Bergeron, A M

    1995-03-01

    After an anecdotal study of allergy in latex collectors, the author raises the problem of food allergy to latex, in particular in those populations that are historically hypersensitive to the mites that they ingest.

  10. Development of polymer concrete for dike insulation at LNG facilities: Phase 4, Low cost materials

    SciTech Connect

    Kukacka, L.E.

    1991-01-01

    Earlier GRI-sponsored work at Brookhaven National Laboratory has resulted in the development and utilization of insulating polymer concrete composites (IPC) as a means of reducing the evaporation rate of liquified natural gas in the event of a spill into a containment dike, thereby improving the safety at these sites. Although all of the required properties can be attained with the IPC, it was estimated that a low-cost replacement for the expensive organic binder would be necessary before use of the material would be cost-effective. In the current program, several latex modified cement formulations were evaluated and the most promising one identified. A mixture of two carboxylated styrene-butadiene latexes was selected for use in detailed laboratory property characterizations and a subsequent field evaluation. When compared to the properties of IPC, the latex-modified insulating materials display somewhat higher thermal conductivities, greater permeability to water, and reduced strength. However, these properties still meet most of the performance criteria, and the unit cost of the material is less than one-fifth that of IPC made with epoxy binders. When installed as a 0.75-in. thick overlay, material costs are estimated to be $1.00/ft{sup 2}.

  11. Binding kinetics of magnetic nanoparticles on latex beads and yeast cells studied by magnetorelaxometry

    NASA Astrophysics Data System (ADS)

    Eberbeck, Dietmar; Bergemann, Christian; Hartwig, Stefan; Steinhoff, Uwe; Trahms, Lutz

    2005-03-01

    The ion exchange mediated binding of magnetic nanoparticles (MNP) to modified latex spheres and yeast cells was quantified using magnetorelaxometry. By fitting subsequently recorded relaxation curves, the kinetics of the binding reactions was extracted. The signal of MNP with weak ion exchanger groups bound to latex and yeast cells scales linearly with the concentration of latex beads or yeast cells whereas that of MNP with strong ion exchanger groups is proportional to the square root of concentration. The binding of the latter leads to a much stronger aggregation of yeast cells than the former MNP.

  12. Latex sensitivity: an occupational health strategic plan.

    PubMed

    McCormack, B; Cameron, M; Biel, L

    1995-04-01

    1. Health care workers, due to ongoing exposure to latex products, may be at risk of developing latex sensitivity. 2. The spectrum of reactions related to medical glove use varies in severity. Awareness of latex sensitivity is heightened through worker education. 3. Guidelines and interventions for occupational health nurses are outlined so that workers who present with symptoms of occupational sensitivities related to latex products can be identified and assessed. 4. Occupational health nurses are effective resources for workers and managers on issues of latex allergy and appropriate accommodation.

  13. [Food-induced anaphylaxis in latex allergy].

    PubMed

    Abeck, D; Börries, M; Kuwert, C; Steinkraus, V; Vieluf, D; Ring, J

    1994-06-01

    Contact uticaria and anaphylactic reactions to latex-containing rubber products are being recognized with increasing frequency in all kinds of medical disciplines. Recently a number of reports have been published describing anaphylactic reactions to food items in patients with latex allergy. The cases of three patients who developed anaphylactic reactions to both latex and food items are presented, and the importance of the association of latex and cross-reactivity with food items is stressed. The food items that led to anaphylactic reactions were banana and avocado; banana, avocado and buckwheat; and banana, avocado and tomato. The cross-reactivity of latex to buckwheat and tomato has not been reported before.

  14. [Latex allergy--report on two cases].

    PubMed

    Lukesová, S; Krcmová, I; Kopecký, O

    2005-01-01

    In the last few years latex allergy has been increasingly recognised as a potential medical problem because of the increase in frequency and potential severity of latex-mediated reactions. Latex allergy is an IgE-mediated hypersensitivity response to natural rubber latex protein with a variety of clinical signs ranging from contact urticaria, angioedema, asthma, and anaphylaxis. Also IV. type of immunology response can participate in it. In highest risk for latex allergy are patients with spina bifida, but health care workers, latex industry workers, patients with multiple surgical procedures and others who wear gloves are also at risk. Patients with history of atopy belong to the high risk group. Diagnosis is done by positive in vitro tests (EAST, CAP-FEIA, immunoblott etc.) and skin prick test. Allergen avoidance and substitution and the use of latex-safe devices including synthetic gloves are essential for the affected patient. PMID:16193945

  15. How Concrete Is Concrete?

    ERIC Educational Resources Information Center

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  16. Corrosion-resistant sulfur concretes

    NASA Astrophysics Data System (ADS)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  17. Fly ash sulfur concrete

    SciTech Connect

    Head, W.J.; Liao, M.

    1981-05-01

    Two waste products, flyash and elemental sulfur, can be combined with a modifying agent to produce a potentially useful construction material, flyash sulfur concrete. Manufacturing processes and characteristics of this concrete are described. Compared with a conventional crushed stone aggregate, flyash sulfur concrete is a viable highway pavement base course material. The material's strength characteristics are analyzed. (1 diagram, 4 graphs, 2 photos, 9 references, 5 tables)

  18. [Intraoperative anaphylaxis caused by latex surgical gloves].

    PubMed

    Tomita, S; Sugawara, K; Tamakawa, S; Saitoh, Y

    1998-02-01

    A 17-year-old male encountered anaphylaxis caused by latex surgical gloves during emergency surgery under general anesthesia. He had undergone multiple surgical procedures, bladder catheterization and was suffering from atopic dermatitis. The patient developed bronchospasm and circulatory collapse 20 minutes after the start of surgery. Administration of dopamine, aminophylline and methylprednisolone helped to normalize airway pressure and blood pressure. Latex allergy occurs in persons considered at high risk including patient with spina bifida, urogenital abnormalities, atopic dermatitis, health care workers and rubber industry workers. These persons may develop hypersensitivity to latex products. If patients who are suspected to be latex allergy undergo surgical procedures, anesthesiologist should check past history and sensitivity to rubber in detail. In patients known to be allergic to latex, we must avoid latex products, such as surgical gloves, or anesthetic and surgical equipments. PMID:9513338

  19. Modeling the Adsorption of Hydrophobic Ethoxylated Urethane (HEUR) Thickeners onto Latex Surfaces using Self-Consistent Field Theory

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy; van Dyk, Antony; Chatterjee, Tirtha; Wang, Shihu; Larson, Ronald

    2015-03-01

    Hydrophobic Ethoxylated Urethane (HEUR) polymers are widely used as rheology modifiers (thickeners) in waterborne latex paints. Recently, it has been shown that the thickening effect of HEURs in paints is largely determined by their adsorption onto latex surfaces, this adsorption being a function of polymer structure, latex surface chemistry, and total available latex surface. Here, we describe the application of Self-Consistent Field Theory (SCFT) to calculate adsorption isotherms of several model HEURs onto ideal hydrophobic latex surfaces. Unlike earlier SCFT studies of adsorption, we explicitly take into account the role of HEUR micelles and competition between adsorption and micellization. The results are compared with experimental data and coarse-grained molecular dynamic (CG-MD) simulations, and good qualitative and semi-quantitative agreement is found. This work was supported by The Dow Chemical Company.

  20. Wetting and spreading of individual latex particles

    SciTech Connect

    Unertl, W.N.; Luo, Y.; Woodland, D.; Bediwi, A.B.E.; Kamal, M.; El Farrash, A.E.

    1996-12-31

    The wetting and spreading of individual latex particles is an important factor in controlling the mechanical properties of coatings such as those used on paper. The interactions between latex particles that lead to coalescence and film formation has been extensively studied and the basic mechanisms have been identified. Surface aspects of the coalescence and film formation for bulk films and dense monolayers have also been studied including the effects of surfactants. However, in many practical applications, including most paper coatings, latex is present in concentrations that are too small for latex-latex interactions to be important. In these applications, the wetting, spreading, and adhesion of individual latex particles on surfaces of the other constituents of the coating are most important. In spite of its importance, this topic has received little attention. This paper describes measurements of the contact angle {theta} and determination of the work of adhesion W of styrene-butadiene latex particles on calcite, mica, cellophane, and polystyrene surfaces. The effects of humidity and latex glass transition temperature on the wetting and spreading are also described. Some implications for the strength of coatings containing low levels of latex binders are also discussed.

  1. Effect of irradiation on the prevulcanized latex/low nitrosamines latex blends

    SciTech Connect

    Ibrahim, Pairu; Zin, Wan Manshol Wan; Daik, Rusli

    2015-09-25

    Radiation Prevulcanized Natural Rubber Latex (RVNRL) was blended with Low Nitrosamines Latex (LNL) at different composition ratio. Methyl Metachrylate (MMA) was added for grafting onto the blended latex. Blended latex was subjected to gamma irradiation at various doses up to 8kGy. The mechanical properties and FTIR analysis were investigated as a function of the blended composition and irradiation dose. It was found that blending at specific ratio and gamma irradiation at specific dose led to significant improvement on the properties of the latex. The optimum mechanical properties was attained at a total blending ratio of 70% RVNRL and 30% of LNL.

  2. RADIATION INDUCED VULCANIZATION OF RUBBER LATEX

    DOEpatents

    Mesrobian, R.B.; Ballantine, D.S.; Metz, D.J.

    1964-04-28

    A method of vulcanizing rubber latex by exposing a mixture containing rubber latex and from about 15 to about 21.3 wt% of 2,5-dichlorostyrene to about 1.1 megarads of gamma radiation while maintaining the temperature of the mixture at a temperature ranging between from about 56 to about 59 deg C is described. (AEC)

  3. Enhancement of polyisoprene latex production

    NASA Technical Reports Server (NTRS)

    Bauman, Albert J. (Inventor)

    1979-01-01

    Production of high molecular weight polyisoprene latex is enhanced by administering to plants, particularly Guayule Plants, an amine containing at least one two-carbon chain substituent and preferably substituted trialkylamine of the general structure: ##STR1## where R.sub.4, R.sub.5 and R.sub.6 are alkyl, preferably ethyl and at least one of R.sub.4, R.sub.5 and R.sub.6 is preferably an electron withdrawing group substituted aryloxy or arylthio ethyl group.

  4. [2009 Japanese Society of Latex Allergy guidelines for the safe management of latex allergy].

    PubMed

    Mizuno, Ju; In-Nami, Hiroshi

    2011-06-01

    Latex allergy is an IgE-mediated reaction to natural latex antigen. Operating room equipment frequently includes medical devices, such as surgical gloves, intravenous lines, and urinary catheters, which are made from latex or contain latex. These products can trigger an allergic reaction that can result in anaphylactic shock. Removal of natural rubber and latex-containing products from the operating room and avoidance of external and internal exposure of patients to latex antigen will prevent such allergic reactions. Updated guidelines for the safe management of latex allergy were published in 2009 by the Japanese Society of Latex Allergy. The previous guidelines regarding this topic were published in 2006. The new guidelines consist of 11 chapters that deal with background, exposure to latex antigen and development of sensitization, high-risk groups, natural rubber products, allergic reactions triggered by natural rubber products, diagnosis, latex-fruit syndrome, countermeasures and treatments in emergencies, prevention and safe management in the hospital, countermeasures in daily life, and limits for application of the guidelines. We had a case that required management according to the 2009 guidelines. A 49-year-old male doctor with a history of allergy to latex gloves was scheduled for laparoscopic cholecystectomy under general and epidural anesthesia for recurrent, acute cholecystitis. The anesthesia and operation were performed uneventfully with latex-free medical devices and machines in a latex-safe environment in the operating room under the new guidelines. Safe anesthetic management under the 2009 guidelines should be available for all operations in Japan on patients with latex allergy. PMID:21710779

  5. Nitrile versus Latex for Glove Juice Sampling.

    PubMed

    Landers, Timothy F; Dent, Anthony

    2014-01-01

    The objective of this study was to explore the utility of nitrile gloves as a replacement for latex surgical gloves in recovering bacteria from the hands. Two types of nitrile gloves were compared to latex gloves using the parallel streak method. Streaks of Klebsiella pneumoniae and Staphylococcus aureus were made on tryptic soy agar plates, and the zones of inhibition were measured around pieces of glove material placed on the plates. Latex gloves produced a mean zone of inhibition of 0.28 mm, compared to 0.002 mm for nitrile gloves (p<.001). While the parallel streak method is not intended as a quantitative estimate of antimicrobial properties, these results suggest that nitrile may be a viable alternative to latex in glove juice sampling methods, since nitrile avoids the risk of latex exposure. PMID:25333880

  6. Jackfruit anaphylaxis in a latex allergic patient.

    PubMed

    Wongrakpanich, Supakanya; Klaewsongkram, Jettanong; Chantaphakul, Hiroshi; Ruxrungtham, Kiat

    2015-03-01

    Several fruits have been reported to crossreact with latex antigen in latex allergy patients but little is known regarding tropical fruits in particular. Here we report the case of a 34-year old nurse who developed anaphylaxis following the ingestion of dried jackfruit (Artocarpus heterophyllus). The patient had a history of chronic eczema on both hands resulting from a regular wear of latex gloves. She and her family also had a history of atopy (allergic rhinitis and/or atopic dermatitis). The results of skin prick tests were positive for jackfruit, latex glove, kiwi and papaya, but the test was negative for banana. While we are reporting the first case of jackfruit anaphylaxis, further research needs to be conducted to identify the mechanisms underlying it. In particular, in-vitro studies need to be designed to understand if the anaphylaxis we describe is due to a cross reactivity between latex and jackfruit or a coincidence of allergy to these 2 antigens. PMID:25840636

  7. Jackfruit anaphylaxis in a latex allergic patient.

    PubMed

    Wongrakpanich, Supakanya; Klaewsongkram, Jettanong; Chantaphakul, Hiroshi; Ruxrungtham, Kiat

    2015-03-01

    Several fruits have been reported to crossreact with latex antigen in latex allergy patients but little is known regarding tropical fruits in particular. Here we report the case of a 34-year old nurse who developed anaphylaxis following the ingestion of dried jackfruit (Artocarpus heterophyllus). The patient had a history of chronic eczema on both hands resulting from a regular wear of latex gloves. She and her family also had a history of atopy (allergic rhinitis and/or atopic dermatitis). The results of skin prick tests were positive for jackfruit, latex glove, kiwi and papaya, but the test was negative for banana. While we are reporting the first case of jackfruit anaphylaxis, further research needs to be conducted to identify the mechanisms underlying it. In particular, in-vitro studies need to be designed to understand if the anaphylaxis we describe is due to a cross reactivity between latex and jackfruit or a coincidence of allergy to these 2 antigens.

  8. Nitrile versus Latex for Glove Juice Sampling

    PubMed Central

    Landers, Timothy F.; Dent, Anthony

    2014-01-01

    The objective of this study was to explore the utility of nitrile gloves as a replacement for latex surgical gloves in recovering bacteria from the hands. Two types of nitrile gloves were compared to latex gloves using the parallel streak method. Streaks of Klebsiella pneumoniae and Staphylococcus aureus were made on tryptic soy agar plates, and the zones of inhibition were measured around pieces of glove material placed on the plates. Latex gloves produced a mean zone of inhibition of 0.28 mm, compared to 0.002 mm for nitrile gloves (p<.001). While the parallel streak method is not intended as a quantitative estimate of antimicrobial properties, these results suggest that nitrile may be a viable alternative to latex in glove juice sampling methods, since nitrile avoids the risk of latex exposure. PMID:25333880

  9. Adhesion of latex films. Influence of surfactants

    SciTech Connect

    Charmeau, J.Y.; Kientz, E.; Holl, Y.

    1996-12-31

    In the applications of film forming latexes in paint, paper, coating, adhesive, textile industries, one of the most important property of latex films is adhesion onto a support. From the point of view of adhesion, latex films have two specificities. The first one arises from the particular structure of the film which is usually not homogeneous but retains to a certain extent the memory of the particles it was made from. These structure effects are clearly apparent when one compares mechanical or adhesion properties of pure latex films and of films of the same polymers but prepared from a solution. Latex films show higher Young`s moduli and lower adhesion properties than solution films. The second specificity of latex films comes from the presence of the surfactant which was used in the synthesis and as stabilizer for the latex. Most industrial latexes contain low amounts of surfactant, typically in the range 0.1 to 2-3 wt%. However, being usually incompatible with the polymer, the surfactant is not homogeneously distributed in the film. It tends to segregate towards the film-air or film-support interfaces or to form domains in the bulk of the film. Distribution of surfactants in latex films has been studied by several authors. The influence of the surfactant on adhesion, as well as on other properties, is thus potentially very important. This article presents the results of the authors investigation of surfactant effects on adhesion properties of latex films. To the authors knowledge, there is no other example, in the open literature, of this kind of study.

  10. Extractable proteins from field radiation vulcanized natural rubber latex

    NASA Astrophysics Data System (ADS)

    Parra, Duclerc F.; Pinto Martins, Carlos Felipe; Collantes, Chirinos H. D.; Lugao, Ademar B.

    2005-07-01

    The type I allergy associated with the use of natural rubber latex (NRL) products is caused by the NRL proteins leached by the sweat or other body fluids. Makuuchi's group proposed for the first time the proteins removal by the addition of water-soluble polymers (WSP) on radiation vulcanization of natural rubber latex (RVNRL) that is a promising process under development in many countries. In this study, Brazilian field natural rubber was irradiated with a 60Co gamma source to reduce the content of WSP in the final product. WSP was used as additive to improve the extraction of protein. After irradiation the RVNRL was centrifuged to extract the WSP and proteins. The analytical methodology for protein content was based on the modified Lowry method according to ASTM D5712. Protein determination was carried out in serum of latex and in the extracts of the gloves. The concentration of extractable water-soluble proteins in serum of irradiated field NRL (NRL1), not irradiated one (NRL2); of twice centrifuged sample with polymer additive NRL (NRL3) and of the glove manufactured (NRLG) are compared with commercial glove (CG). The irradiation process increases the extractable water-soluble proteins, EP, as reported in the literature. In this study the use of polymeric additive on the bi-centrifugation process to remove protein was successful and the EP of the glove obtained in NRL3 was at around 40% of the commercial glove.

  11. Development of polymer concrete for dike insulation at LNG facilities: Phase 4, Low cost materials. Final report, September 1, 1987--April 30, 1990

    SciTech Connect

    Kukacka, L.E.

    1991-01-01

    Earlier GRI-sponsored work at Brookhaven National Laboratory has resulted in the development and utilization of insulating polymer concrete composites (IPC) as a means of reducing the evaporation rate of liquified natural gas in the event of a spill into a containment dike, thereby improving the safety at these sites. Although all of the required properties can be attained with the IPC, it was estimated that a low-cost replacement for the expensive organic binder would be necessary before use of the material would be cost-effective. In the current program, several latex modified cement formulations were evaluated and the most promising one identified. A mixture of two carboxylated styrene-butadiene latexes was selected for use in detailed laboratory property characterizations and a subsequent field evaluation. When compared to the properties of IPC, the latex-modified insulating materials display somewhat higher thermal conductivities, greater permeability to water, and reduced strength. However, these properties still meet most of the performance criteria, and the unit cost of the material is less than one-fifth that of IPC made with epoxy binders. When installed as a 0.75-in. thick overlay, material costs are estimated to be $1.00/ft{sup 2}.

  12. [Latex allergy - an emerging health care problem.].

    PubMed

    Gislason, D; Bjornsdottir, U S

    1996-08-01

    Since immediate hypersensitivity reaction to natural rubber was described 17 years ago, the incidence of latex allergy has been increasing rapidly. This is in part due to a growing awareness of the problem along with improved diagnostic methods. Additionally, in accordance with universal health care plans and the HIV epidemic, more rubber products such as latex gloves and condoms are in general use. Changes in methods of rubber production may also contribute to the increasing prevalence in latex allergy. Individuals at greatest risk for developing latex allergy are patients who have undergone multiple operations. These include children with myelomeningocele (spina bifida) and congenital defects of the urinary tract. Another high risk group includes health care providers and individuals working in rubber production. Latex containing products are in general use in the hospital setting as well as in the home environment. They can therefore pose a great risk to sensitized patients if prophylactic measures are not undertaken. Defining high risk patients and subsequent diagnosis with appropriate skin tests are important. Patients with latex allergy must then be provided with self-administered adrenalin (Epi-pen) and instructed in avoidance measures. In this article we describe 23 individuals who have been diagnosed allergic to latex in Iceland. PMID:20065424

  13. Altered surface character of stretched condom latex.

    PubMed

    Jay, G D; Drummond, E; Lane, B

    1992-02-01

    A new type of imperfection in condom latex, present during moderate stretching, was observed by low magnification scanning electron microscopy. The normally smooth surface of relaxed natural latex was transformed into an accordion-like arrangement of ripples in addition to tears. A corollary experiment with Alcian blue dye placed into both stretched and unstretched condoms leaked no dye. These surface features are consistent with latex acting as a molecular barrier. The tears may represent areas of lowered mechanical resistance and raise questions concerning quality control.

  14. Exercise with latex sport bands represents a risk for latex allergic patients.

    PubMed

    Untersmayr, Eva; Lukschal, Anna; Hemmer, Wolfgang; Harwanegg, Christian; Breiteneder, Heimo; Jarisch, Reinhard; Scheiner, Otto; Jensen-Jarolim, Erika

    2008-01-29

    Based on two clinical observations of adverse reactions during exercise with latex sport bands, we aimed to assess the possible risk for allergic patients posed by this equipment by investigating allergen content and IgE binding potential. Protein extracts of three different latex sport bands were characterized with sera of latex allergic patients. The IgE recognition profile of the allergic patients was identified by component resolved diagnosis and the allergen composition of the extracts was characterized by inhibition assays with the recombinant latex allergens Hev b 1, 3, 5, 6.02, and 8. The sera showed pronounced IgE binding to all three blotted extracts, however with diverse patterns. Inhibition assays revealed the presence of Hev b 1, 3, 5, and 8 in latex sport band extracts. The clinical relevance of contained allergens was demonstrated by strong skin reactions when testing with latex sport bands. From our results we conclude that latex sport bands contain clinically relevant allergens and may cause latex allergic individuals to experience allergic symptoms, potentially amplified by exercise-induced mechanisms. Even though latex is labeled on products, it is important that patients as well as athletic trainers and physical therapists recognize the risk of adverse reactions with these bands.

  15. [Latex ligation in treatment of chronic hemorrhoids].

    PubMed

    Ektov, V N; Somov, K A

    2015-01-01

    We analyzed the results of treatment of 432 patients with chronic hemorrhoids using different variants of latex ligation. New technique including ligation of mucosa and submucosa of low-ampullar rectum providing ligation of hemorrhoidalvessels, lifting and recto-anal repair is developed and suggested. This method is advisable to use in case of chronic internal hemorrhoids stages I and II. The authors recommend simultaneous combined ligation of mucosa of low-ampullar rectum and internal hemorrhoids for stages III and IV. Different variants of latex ligation with external hemorrhoids excision were used in 103 patients. Pointed variants of latex ligation preserve important advantages including mini-invasiveness, simplicity and wide availability, low cost. Good remote results were obtained after these procedures in 87.3% of observations. Suggested tactics extends use of latex ligation and increases its effectiveness in treatment of different stages and forms of chronic hemorrhoids.

  16. Preparation and characterization of latex films photo-immobilized with IFN-α.

    PubMed

    Wu, Lifang; Hu, Kaikai; Zhang, Li; Chen, Wuya; Chen, Xiaohui; You, Rong; Yin, Liang; Guan, Yan-Qing

    2016-09-01

    We developed a biomaterial by photo-immobilizing interferon-α (IFN-α) on the surface of latex condom films for the prevention and treatment of cervicitis, cervical cancers and diseases caused by cervical virus. The IFN-α modification by photoactive N-(4-azidobenzoyloxy) succinimide was characterized on a nano-scale by spectroscopy analysis and micro morphology. The anti-bacterial, anti-cancer, and anti-viral effects of the modified bioactive latex films were evaluated by antibacterial susceptibility testing, Gram staining, flow cytometry, immunofluorescence, and Western blotting. Our results showed that the photo-immobilized IFN-α latex films effectively inhibited the growth of both Neisseria gonorrhoeae and human cervical cancer HeLa cells. Moreover, the expression of anti-viral proteins, including P56, MxA, and 2', 5'-OAS, in the human cervical epithelial cell line NC104 was significantly increased by photo-immobilized IFN-α latex films. Taken together, these results suggest that photo-immobilized IFN-α latex films may have therapeutic effects against cervicitis, cervical cancers, and cervical virus.

  17. Preparation and characterization of latex films photo-immobilized with IFN-α.

    PubMed

    Wu, Lifang; Hu, Kaikai; Zhang, Li; Chen, Wuya; Chen, Xiaohui; You, Rong; Yin, Liang; Guan, Yan-Qing

    2016-09-01

    We developed a biomaterial by photo-immobilizing interferon-α (IFN-α) on the surface of latex condom films for the prevention and treatment of cervicitis, cervical cancers and diseases caused by cervical virus. The IFN-α modification by photoactive N-(4-azidobenzoyloxy) succinimide was characterized on a nano-scale by spectroscopy analysis and micro morphology. The anti-bacterial, anti-cancer, and anti-viral effects of the modified bioactive latex films were evaluated by antibacterial susceptibility testing, Gram staining, flow cytometry, immunofluorescence, and Western blotting. Our results showed that the photo-immobilized IFN-α latex films effectively inhibited the growth of both Neisseria gonorrhoeae and human cervical cancer HeLa cells. Moreover, the expression of anti-viral proteins, including P56, MxA, and 2', 5'-OAS, in the human cervical epithelial cell line NC104 was significantly increased by photo-immobilized IFN-α latex films. Taken together, these results suggest that photo-immobilized IFN-α latex films may have therapeutic effects against cervicitis, cervical cancers, and cervical virus. PMID:27137809

  18. Natural rubber latex allergy: spectrum, diagnostic approach, and therapy.

    PubMed

    Woods, J A; Lambert, S; Platts-Mills, T A; Drake, D B; Edlich, R F

    1997-01-01

    Latex allergy has reached epidemic proportions in the United States and is increasingly recognized as a significant contributor to morbidity and mortality during medical and surgical procedures. Ultimately, many of the affected patients with recognized latex sensitivity and those who are not yet diagnosed will receive treatment for their allergic reactions to latex in emergency departments. Consequently, emergency physicians must have a comprehensive understanding of the etiology, epidemiology, pathogenesis, treatment, and management of these challenging patients. Groups at high risk include spina bifida cystica patients, health care workers, latex industry workers, specific food-allergy patients, and patients with a history of atopy or multiple surgical procedures. Sensitization to latex antigens is commonly encountered in health care workers wearing latex gloves with high latex allergen concentrations and in workers using powdered latex surgical gloves. Exposure to air-borne allergens and water-soluble IgE reactive latex antigens from natural rubber latex products in sensitized individuals can result in type I (immediate) hypersensitivity reactions. Clinical manifestations include contact urticaria, dermatitis, allergic rhinitis, conjunctivitis, asthma, angioedema, and anaphylaxis. Diagnostic tools include serological assays and skin prick testing. At present, latex avoidance is the only available treatment and is the key to preventing allergic reactions in latex-sensitized individuals. Health care worker sensitization to latex antigens in natural rubber products is becoming an increasing contributor to workers' liability and disability claims. Specific action can be taken to reduce occupational and patient exposure to latex antigens. PMID:9017491

  19. Effect of copolymer latexes on physicomechanical properties of mortar containing high volume fly ash as a replacement material of cement.

    PubMed

    Negim, El-Sayed; Kozhamzharova, Latipa; Gulzhakhan, Yeligbayeva; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

  20. Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

    PubMed Central

    Kozhamzharova, Latipa; Gulzhakhan, Yeligbayeva; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes. PMID:25254256

  1. Uptake of Latex Particles by Blood Platelets

    PubMed Central

    White, James G.

    1972-01-01

    The incorporation of large particulates by blood platelets is considered identical to the ingestion of bacteria by neutrophils, and is referred to as platelet phagocytosis. However, bacteria enter neutrophils in sealed vacuoles derived from the cell wall, and products deposited in the vacuoles during neutrophil degranulation are confined almost exclusively to the phagolysosomes. Products released from platelet storage organelles after uptake of foreign particles, on the other hand, are extruded to the cell exterior. The basis for this unusual difference in the phagocytic response of platelets and neutrophils has been sought in the present investigation. Combined electron microscopic and cytechemical study of platelet-latexspherule interaction revealed that platelets do not phagocytize in the usual sense. Most of the latex particles observed in platelets were lodged in channels of the open canalicular system. Channels which contained latex did not pinch off to form sealed phagocytic vacuoles, but remained open. An electron-dense tracer, lanthanum nitrate, was able to penetrate into the channels and outline the ingested latex particles. Therefore, platelets do not phagocytize latex, but sequester the spherules in preformed membranous invaginations. The persistence of open channel communication with the exterior after latex uptake may explain why platelets extrude secretory products, rather than confine them to phagolysosomes. ImagesFig 4Fig 1Fig 5Fig 2Fig 6Fig 3 PMID:5086899

  2. The morphology of emulsion polymerized latex particles

    SciTech Connect

    Wignall, G.D.; Ramakrishnan, V.R.; Linne, M.A.; Klein, A.; Sperling, L.H.; Wai, M.P.; Gelman, R.A.; Fatica, M.G.; Hoerl, R.H.; Fisher, L.W.

    1987-11-01

    Under monomer starved feed conditions, emulsion polymerization of perdeuterated methyl methacrylate and styrene in the presence of preformed polymethylmethacrylate latexes resulted in particles with a core-shell morphology, as determined by small-angle neutron scattering (SANS) analysis for a hollow sphere. The locus of polymerization of the added deuterated monomer is therefore at the particle surface. In similar measurements a statistical copolymer of styrene and methyl methacrylate was used as seed particles for further polymerization of trideuteromethyl methacrylate. The resulting polymer latex was again shown to have a core-shell morphological structre as determined by SANS. SANS experiments were also undertaken on polystyrene latexes polymerized by equilibrium swelling methods, with deuterated polymer forming the first or second step. The experiments covered a molecular weight range of 6 x 10/sup 4/ < M < 6 x 10/sup 6/ g/mol. For M > 10/sup 6/ the molecular weights are consistent with the experimental errors, indicating that the deuterium labeled molecules are randomly distributed in the latex. These results led to the finding that the polymer chains were constrained in the latex particles by factors of 2 to 4 from the relaxed coil dimensions. For M < 10/sup 6/ g/mol SANS gave zero angle scattering intensities much higher than expected on the basis of a random distribution of labeled molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights. 25 refs., 6 figs., 3 tabs.

  3. The Morphology of Emulsion Polymerized Latex Particles

    DOE R&D Accomplishments Database

    Wignall, G. D.; Ramakrishnan, V. R.; Linne, M. A.; Klein, A.; Sperling, L. H.; Wai, M. P.; Gelman, R. A.; Fatica, M. G.; Hoerl, R. H.; Fisher, L. W.

    1987-11-01

    Under monomer starved feed conditions, emulsion polymerization of perdeuterated methyl methacrylate and styrene in the presence of preformed polymethylmethacrylate latexes resulted in particles with a core-shell morphology, as determined by small-angle neutron scattering (SANS) analysis for a hollow sphere. The locus of polymerization of the added deuterated monomer is therefore at the particle surface. In similar measurements a statistical copolymer of styrene and methyl methacrylate was used as seed particles for further polymerization of trideuteromethyl methacrylate. The resulting polymer latex was again shown to have a core-shell morphological structure as determined by SANS. SANS experiments were also undertaken on polystyrene latexes polymerized by equilibrium swelling methods, with deuterated polymer forming the first or second step. The experiments covered a molecular weight range of 6 x 10{sup 4} 10{sup 6} the molecular weights are consistent with the experimental errors, indicating that the deuterium labeled molecules are randomly distributed in the latex. These results led to the finding that the polymer chains were constrained in the latex particles by factors of 2 to 4 from the relaxed coil dimensions. For M < 10{sup 6} g/mol SANS gave zero angle scattering intensities much higher than expected on the basis of a random distribution of labeled molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights.

  4. Recombinant albumin monolayers on latex particles.

    PubMed

    Sofińska, Kamila; Adamczyk, Zbigniew; Kujda, Marta; Nattich-Rak, Małgorzata

    2014-01-14

    The adsorption of recombinant human serum albumin (rHSA) on negatively charged polystyrene latex micro-particles was studied at pH 3.5 and the NaCl concentration range of 10(-3) to 0.15 M. The electrophoretic mobility of latex monotonically increased with the albumin concentration in the suspension. The coverage of adsorbed albumin was quantitatively determined using the depletion method, where the residual protein concentration was determined by electrokinetic measurements and AFM imaging. It was shown that albumin adsorption was irreversible. Its maximum coverage on latex varied between 0.7 mg m(-2) for 10(-3) M NaCl to 1.3 mg m(-2) for 0.15 M NaCl. The latter value matches the maximum coverage previously determined for human serum albumin on mica using the streaming potential method. The increase in the maximum coverage was interpreted in terms of reduced electrostatic repulsion among adsorbed molecules. These facts confirm that albumin adsorption at pH 3.5 is governed by electrostatic interactions and proceeds analogously to colloid particle deposition. The stability of albumin monolayers was measured in additional experiments where changes in the latex electrophoretic mobility and the concentration of free albumin in solutions were monitored over prolonged time periods. Based on these experimental data, a robust procedure of preparing albumin monolayers on latex particles of well-controlled coverage and molecule distribution was proposed. PMID:24354916

  5. Investigation of natural latex rubber gloves

    SciTech Connect

    Vessel, E.M.

    1993-03-19

    Seventy five percent of natural latex rubber gloves used in laboratories at the Savannah River Site are not reused. A cost analysis performed by the SRS Procurement Department determined that a net savings of $1,092,210 could be achieved annually by recycling latex rubber gloves. The Materials Technology Section, at the request of the Procurement Department, examined some mechanical and chemical properties of latex rubber gloves manufactured by Ansell Edmont, which had been purchased by the site specifications for protective clothing. It also examined mechanical properties of re-cycled gloves purchased by specifications and of {open_quotes}off the shelf{close_quotes} gloves manufactured by North Brothers Company. Finally, water vapor transmission studies, simulating tritium permeation, were performed on gloves from both manufacturers. These studies were performed to determine whether latex rubber gloves can be recycled or whether using only new, unwashed gloves is required in areas where tritium exposure is a possibility. The results of these studies indicate that the acceptable glove characteristics, required in the WSRC Manual 5Q1.11, Protective Clothing Specifications, are not adversely affected after washing and drying the gloves manufactured by Ansell Edmont for seven cycles. Results also indicate that natural latex rubber gloves manufactured by North Brothers comply with most of the acceptable glove characteristics specified in the WSRC Manual 5Q1.11. Statistical analysis of the water vapor permeation data show that there is no correlation between permeation rates and the manufacturer.

  6. LaTeX for Agricultural Extension Professionals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    LaTeX is a free open source document preparation system for professional quality documents and presentation materials. Extension professionals, trying to reach their audience though various forms of printed and online resources, can benefit from the vast potential of LaTeX. Using LaTeX empowers the ...

  7. CHARACTERIZATION AND RECYCLING OF WASTE WATER FROM GUAYULE LATEX EXTRACTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule commercialization for latex production to be used in medical products and other applications is now a reality. Currently, waste water following latex extraction is discharged into evaporation ponds. As commercialization reaches full scale, the liquid waste stream from latex extraction will b...

  8. The first products made in space: Monodisperse latex particles

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; El-Aasser, M. S.; Micale, F. J.; Sudol, E. D.; Tseng, C.-M.; Sheu, H.-R.; Kornfeld, D. M.

    1988-01-01

    The preparation of large particle size 3 to 30 micrometer monodisperse latexes in space confirmed that original rationale unequivocally. The flight polymerizations formed negligible amounts of coagulum as compared to increasing amounts for the ground-based polymerizations. The number of offsize large particles in the flight latexes was smaller than in the ground-based latexes. The particle size distribution broadened and more larger offsize particles were formed when the polymerizations of the partially converted STS-4 latexes were completed on Earth. Polymerization in space also showed other unanticipated advantages. The flight latexes had narrower particle size distributions than the ground-based latexes. The particles of the flight latexes were more perfect spheres than those of the ground-based latexes. The superior uniformity of the flight latexes was confirmed by the National Bureau of Standards acceptance of the 10 micrometer STS-6 latex and the 30 micrometer STS-11 latexes as Standard Reference Materials, the first products made in space for sale on Earth. The polymerization rates in space were the same as those on Earth within experimental error. Further development of the ground-based polymerization recipes gave monodisperse particles as large as 100 micrometer with tolerable levels of coagulum, but their uniformity was significantly poorer than the flight latexes. Careful control of the polymerization parameters gave uniform nonspherical particles: symmetrical and asymmetrical doublets, ellipsoids, egg-shaped, ice cream cone-shaped, and popcorn-shaped particles.

  9. [Cicatrization effect of Jatropha curcas latex (Angiospermae: Euforbiaceae)].

    PubMed

    Salas, J; Tello, V; Zavaleta, A; Villegas, L; Salas, M; Fernández, I; Vaisberg, A

    1994-01-01

    The wound healing effects of Jathopha curcas latex upon surgical wound produced in Balb/c mice skin, were studied with a modification of the Hoowes-Sooy-Harvey method. The effects of topical treatment using single 50 ul doses of latex at different dilutions (10% to 100%) was compared with a multiple dose treatment (four 25 ul/dose q12h, latex 5% to 100%). The single dose treatment with 10%, 50% or 100% latex and the multiple dose treatment with dilutions between 5% and 10%, have a healing effect but only on males. The multiple dose treatment with 50% or pure undiluted latex produced caustic lesions to treated skin.

  10. Immediate-type latex hypersensitivity in a hairdresser.

    PubMed

    Sajjachareonpong, Praneet; Lee, Adriene; Nixon, Rosemary

    2002-05-01

    Hairdressers commonly develop contact dermatitis caused by either skin irritants or allergens to which they are exposed. Those using latex gloves are also at risk of developing immediate hypersensitivity reactions to latex. We present a hairdresser with hand dermatitis, primarily as a result of immediate-type hypersensitivity to latex causing contact urticaria, diagnosed with radioallergosorbent testing. Only three previous studies have reported latex allergy in hairdressers. This condition needs to be considered as a differential diagnosis in hairdressers presenting with hand dermatitis and a history of wearing either rubber or disposable latex gloves. PMID:11982576

  11. Latex allergy: a relevant issue in the general pediatric population.

    PubMed

    Lee, M H; Kim, K T

    1998-01-01

    Although latex allergy is a widely recognized problem of the pediatric myelomeningocele population and of frequent users of latex products, it is often overlooked in the general pediatric population. The prevalence of latex in common household items and in medical environments increases one's exposure and thus one's possibility of sensitization to latex. Latex allergy may range from mild local reactions such as erythema to more severe systemic reactions such as asthma or anaphylaxis. The immunoglobulin E-mediated mechanism of these reactions has been confirmed serologically by the presence of latex-specific immunoglobulin E with radioallergosorbent testing. Because avoidance of latex is currently the only way to prevent reactions, the identification of household items that contain latex is extremely important. However, because inadvertent exposure to latex is not uncommon, Medic-Alert bracelets and an Epi-Pen should be provided for children allergic to latex. Pediatric nurses should consider latex allergy as a possible diagnosis in situations of unexplained allergic or anaphylactic reactions and should be aware of optimal therapeutic interventions. PMID:9987254

  12. Triterpenoid biosynthesis in Euphorbia lathyris latex

    SciTech Connect

    Hawkins, D.R.

    1987-11-01

    The structures of triterpenols, not previously been known, from Euphorbia lathyris latex are reported. A method for quantifying very small amounts of these compounds was developed. Concerning the biochemistry of the latex, no exogenous cofactors were required for the biosynthesis and the addition of compounds such as NADPAH and ATP do not stimulate the biosynthesis. The addition of DTE or a similar anti-oxidant was found to help reduce the oxidation of the latex, thus increasing the length of time that the latex remains active. The requirement of a divalent cation and the preference for Mn in the pellet was observed. The effect of several inhibitors on the biosynthesis of the triterpenoids was examined. Mevinolin was found to inhibit the biosynthesis of the triterpenoids from acetate, but not mevalonate. A dixon plot of the inhibition of acetate incorporation showed an I/sub 50/ concentration of 3.2 ..mu..M. Fenpropimorph was found to have little or no effect on the biosynthesis. Tridemorph was found to inhibit the biosynthesis of all of the triterpenoids with an I/sub 50/ of 4 ..mu..M. It was also observed that the cyclopropyl containing triterpenols, cycloartenol and 24-methylenecycloartenol were inhibited much more strongly than those containing an 8-9 double bond, lanosterol and 24-methylenelanosterol. The evidence indicates, but does not definetely prove, that lanosterol and 24-methylenelanosterol are not made from cycloartenol and 24-methylenecycloartenol via a ring-opening enzyme such as cycloeucalenol-obtusifoliol isomerase. The possibilty that cycloartenol is made via lanosterol was investigated by synthesizing 4-R-4-/sup 3/H-mevalonic acid and incubating latex with a mixture of this and /sup 14/C-mevalonic acid. From the /sup 3/H//sup 14/C ratio it was shown that cycloartenol and 24-methylenecycloartenol are not made via an intermediate containing as 8-9 double bond. 88 refs., 15 figs., 30 tabs.

  13. Latex sensitivity among hospital employees and atopic children.

    PubMed

    Saraçlar, Y; Cetinkaya, F; Tuncer, A; Sekerel, B; Hovanec-Burns, D; Unver, E

    1998-01-01

    Allergic reactions to latex products are an important health problem for health care workers and children. To investigate the prevalence of latex and latex-associated food sensitivities among hospital employees and atopic children, 61 hospital employees (44 nurses, 13 cleaning staff, 4 technicians) and 40 atopic children were evaluated by in vivo and in vitro testing methods. All subjects were also skin prick tested with common inhalant allergens and some cross-reactive food allergens to latex. In addition, all subjects were evaluated using an enzyme-linked immunometric assay for detection of specific IgE to inhalant allergens and to the known food latex cross-reactant food allergens (banana, chestnut, peanut and kiwi fruit). Latex challenges were performed in 12 history-negative and anti-latex IgE positive atopic children. Seven of the 61 hospital staff (11.4%) and four of the 40 atopic children (10%) showed skin reactivity to latex. By serologic testing, hypersensitivity to latex was found in 30 subjects, to banana in 23, to chestnut in 37, to peanut in 32 and to kiwi fruit in 22 subjects. Latex challenges were negative in all of the children who were tested. Total IgE was higher than expected in 32 subjects and 50 individuals tested positive for specific IgE to common inhalant allergens (AlaTOP). These results indicate that latex allergy may be a health problem for our hospital staff and atopic children. In vitro testing may detect latex-specific IgE in atopic children even when no history of an adverse reaction to latex is present.

  14. Latex allergy: the perspective from the surgical suite.

    PubMed

    Elliott, Beth A

    2002-08-01

    Latex allergy in the perioperative setting presents unique challenges to the health care system. Specific needs of the latex-sensitive patient are paramount, but consideration must also include the impact on health care workers vis-a-vis latex sensitization, environmental allergen control, and barrier protection against blood-borne pathogens. It has been well documented that the greatest source of latex aeroallergen in the surgical setting is latex gloves (both sterile and nonsterile). Levels of latex aeroallergen correlate strongly with use of high-allergen and powdered gloves, total number of gloves used, and the hours of activity in a given environment. A significant reduction in aeroallergen (>10-fold) can be achieved by switching to low-allergen gloves. Ready availability of and encouragement to use nonlatex alternatives when appropriate can further reduce exposure to latex allergens. Since 1998, the Food and Drug Administration has required all medical devices (or their packaging) that contain natural rubber latex to be so labeled. In addition, industry has responded with a host of latex-free products for use in patient care. This has helped eliminate a great deal of confusion about which products are safe for use with latex-sensitive individuals. However, despite significant efforts to educate the public and the health care industry regarding latex allergies, considerable misinformation persists. Provision of a completely latex-free environment in most surgical suites may be unrealistic, but every effort should be made to minimize the unnecessary exposure of patients and health care workers to latex allergens in this high-risk arena. PMID:12170252

  15. Latex allergy: a health care problem of epidemic proportions.

    PubMed

    Agarwal, Sanjay; Gawkrodger, David J

    2002-01-01

    Latex allergy is one of the major health concerns of the decade. The induction of latex allergy commonly occurs after exposure of skin or mucous membrane to natural rubber latex. It is usually a type I, immediate hypersensitivity reaction mediated by IgE which can range from mild skin erythema to anaphylaxis and death. To manage latex allergy appropriately, prompt and correct diagnosis is essential. This depends primarily on clinical history, latex specific IgE RAST (in vitro) and skin prick test (in vivo). It affects people who are frequently exposed to products made of natural rubber latex, such as, health care workers, workers in the rubber industry and those who have had multiple surgical operations. The prevalence in the general population was estimated at 0.7% in a population study in France, but this can be higher in health care workers (up to 17%) and in patients with spina bifida to almost 65%. Prevention strategies should therefore target at risk population, rather than the population as a whole. At present this primarily involves providing non-powdered latex gloves in hospitals and primary health care centres. However, once latex allergy has been established, the situation becomes more complicated. Health care workers either have to be moved to a latex free environment or in extreme circumstances may have to give up their occupation. For patients undergoing operations most hospitals have adopted a latex free protocol. It is important that this is understood and followed by every member of the staff. Those who have had serious adverse reactions should wear Medi-Alert bracelets and in exceptional circumstances may need to keep epinephrine injections on their person. Future strategies focus on the reduction of allergens during latex manufacture, development of suitable non latex gloves and immunotherapy including desensitisation of latex allergic individuals and development of candidate vaccine. PMID:12095872

  16. [Evaluation of a latex agglutination assay method for the determination of plasmin/alpha 2 plasmin inhibitor complex].

    PubMed

    Murakami, F; Iijima, K; Nakamura, K; Ikawa, S

    1994-06-01

    We evaluated a latex agglutination assay method for concentration of plasmin/alpha 2 plasmin inhibitor complex (PPI) developed recently. The latex reagent consisted of two kinds of latex particles, one was coated with monoclonal antibody against plasmin (JIPPI-3) and another coated with monoclonal antibody against modified alpha 2 plasmin inhibitor (JIPPI-50). A correlation of concentrations of PPI between this method and ordinary EIA kit was very good (r = 0.969). Within-run precision of latex agglutination reagent also was good. The concentrations of PPI in plasmas of 40 in 43 normal subjects were 0-0.8 microgram/ml and others were 0.8-1.6 microgram/ml. Plasma levels of PPI were markedly elevated in patients with DIC. In addition, half of the patients with malignant tumors or liver diseases had increased levels of PPI. 16 of 32 cases with selected diseases (18 malignant tumors, 4 liver diseases, 2 infectious diseases, 2 cerebral contusions, 6 others) showed abnormal levels in PPI (> or = 0.8 microgram/ml) during several days preceding the elevation of FDP. It suggested that PPI could reflect fibrinolysis earlier than FDP. This latex agglutination assay is a simple and rapid method, and specific for the determination of PPI concentration as well as EIA method. We conclude that this assay method is very convenient for clinical use. PMID:8051804

  17. Proteolytic properties of Funastrum clausum latex.

    PubMed

    Morcelle, Susana R; Caffini, Néstor O; Priolo, Nora

    2004-07-01

    As part of a screening of latex endopeptidases from plants growing in Argentina, the presence of proteolytic activity in the latex of Funastrum clausum stems is reported. The proteases present in the crude extract showed the main characteristics of the cysteine proteolytic class, i.e. optimum pH at alkaline range, isoelectric point (pI) higher than 9.0, and inhibition of proteolytic activity by thiol blocking reagents. A remarkable thermal stability was also evident in the crude extract. Endosterolytic preference tried on p-nitrophenyl esters of N-alpha-carbobenzoxy-L-amino acids was higher for the alanine, asparagine and tyrosine derivatives. Preliminary peptidase purification by two-step ionic exchange showed the presence of two proteolytic fractions with molecular masses of approximately 24.0 kDa according to SDS-PAGE. PMID:15261386

  18. A role for a Hevea latex lectin-like protein in mediating rubber particle aggregation and latex coagulation.

    PubMed

    Wititsuwannakul, Rapepun; Pasitkul, Piyaporn; Kanokwiroon, Kamonwan; Wititsuwannakul, Dhirayos

    2008-01-01

    An in vitro aggregation of washed lutoid membrane and rubber particles, respectively, prepared from the bottom (lutoid) fraction and rubber layer of centrifuged fresh latex, leading to the formation of rubber coagulum necessary for a latex coagulation was demonstrated. A Triton X-100 extract of washed lutoid membrane proteins, isolated and prepared from the bottom fraction of centrifuged fresh latex was examined for its role in the latex coagulation process. It induced agglutination of rabbit erythrocytes, indicating the presence of a lectin-like protein. Hevea latex lectin-like protein (HLL) was purified to homogeneity by active chitin binding separation, followed by DEAE-Sepharose chromatography. Its M(r) analyzed by SDS-PAGE was 17 kDa, whereas that determined by gel filtration was 267 kDa. The HLL had a pI value of 7.2. Several glycoproteins were shown to inhibit the HLL-induced hemagglutination. The hemagglutinin activity of HLL was enhanced by Ca(2+). Of most interest was the finding that HLL strongly induced aggregation of the Hevea latex rubber particles (RP). This strong RP aggregation leads to latex coagulation, indicating the possibility that it is involved in the formation of the coagulum that plugs the latex vessel ends and stops the flow of latex upon tapping. In addition, the purified HLL also induced aggregation of RP taken from several other non-Hevea latex producing plants. This might indicate either a common or universal role of this lectin-like protein in RP aggregation and hence latex coagulation. This paper, for the first time, provides clear and unequivocal evidence for either a key biological role or physiological function of an endogenous latex lectin-like protein in the sequential process of latex coagulation. PMID:17897690

  19. LATEX sensitization in elderly: allergological study and diagnostic protocol

    PubMed Central

    2014-01-01

    Background The prevalence of latex allergy varies according to the population studied from 3% to 64%. No data exist in the present literature about elderly people because they were not considered among populations at risk. We report a retrospective observational study of 88 elderly patients of our centre of Dermatology and Allergology at Policlinico Umberto I, University of Rome, Sapienza. Results First and second level diagnostic tests showed latex positivity in 11,4% of patients studied for latex allergy in the elderly population. Conclusions Our study demonstrates a prevalence of elderly-latex sensitization of 11,4%, showing that allergy to latex is a growing disease that can occur at any age. So, we propose these patients as an additional risk category for latex allergy. PMID:24822075

  20. Environmental fate of processed natural rubber latex.

    PubMed

    Lambert, Scott; Sinclair, Chris J; Bradley, Emma L; Boxall, Alistair B A

    2013-07-01

    In this study, processed natural rubber latex was degraded in outdoor aquatic microcosms, under a number of treatment scenarios for 200 days. The analytical strategy adopted aimed to characterise a range of volatile, semi-volatile and non-volatile substances. Zinc, was shown to migrate from the latex into solution and increase in concentration over time. Dissolved compounds for which predicted formulas were generated largely consisted of oxygen containing compounds, and are potential oxidised polyisoprene oligomers of various chain lengths. A classification of samples based on principal component analysis showed a clear separation of the degraded latex samples from the representative controls. This technique identified an increase in the complexity of the substances produced and showed that these substances undergo further degradation and transformation processes. A number of volatile substances were also identified indicating the atmosphere to be a potential receiving environmental compartment for polymer degradates. Overall, the results show that complex mixtures of substances are produced when polymer-based materials degrade under environmental conditions. PMID:23689527

  1. A rubber particle protein specific for Hevea latex lectin binding involved in latex coagulation.

    PubMed

    Wititsuwannakul, Rapepun; Rukseree, Kamonchanok; Kanokwiroon, Kamonwan; Wititsuwannakul, Dhirayos

    2008-03-01

    In the first of this three paper series, an in vitro latex coagulation was shown to arise from aggregation of rubber particles (RP) and lutoid membranes. RP aggregation was shown to be induced by a specific Hevea latex lectin-like protein (HLL) present on the lutoid membrane. In this second paper, a binding protein (BP) ligand counterpart for HLL was identified. This RP-HLLBP, having a specific interaction, with HLL was isolated from RP and characterized. The protein was extracted from the small RP in the presence of a surfactant (0.2% Triton-X-100) and further purified to homogeneity. Purification steps included acetone precipitation, heat-treatment, and column chromatography. The presence of RP-HLLBP was monitored by its ability to compete with erythrocytes in the hemagglutination inhibition (HI) assay. The purified RP-HLLBP had an HI titre of 1.37 microgml(-1), a pI value of 5.4, optimum activity at pH 5-8 and was thermostable up to 60 degrees C. On SDS-PAGE a single glycoprotein with M(r) of 24 kDa was detected while on native PAGE the major Mr was about 120 kDa. The purified RP-HLLBP was shown to inhibit latex coagulation. Chitinase, but no other glycosidase tested, abolished its HI action and inhibited HLL-induced RP aggregation in a competitive dose dependent manner. This indicated the presence of, and role for, N-acetylglucosamine residues in the binding recognition. The Hevea latex lectin-like protein can thus be referred to as a Hevea latex lectin. Based on protein identification by peptide mass fingerprinting, the RP-HLLBP was confirmed to be the small rubber particle protein (SRPP). This work has unambiguously determined the role of an intrinsic RP glycoprotein (RP-HLLBP or SRPP) as a key component in formation of the rubber latex coagulum. PMID:18226821

  2. Content of Asthmagen Natural Rubber Latex Allergens in Commercial Disposable Gloves.

    PubMed

    Bittner, C; Garrido, M V; Krach, L H; Harth, V

    2016-01-01

    The use of natural rubber latex (NRL) gloves in many occupations may lead to latex sensitization, allergic asthma, and skin reactions. Due to their good properties and environmental safety NRL gloves are still being used in the healthcare setting, but also in the food industry, by hairdressers, cleaners, etc. The aim of our study was to assess the protein and NRL allergen content in commercial gloves by different methods, including a new assay. Twenty commercially available NRL gloves were analyzed. Protein extraction was performed according to the international standard ASTM D-5712. Total protein content was measured with a modified Lowry method, NRL content with the CAP Inhibition Assay, the Beezhold ELISA Inhibition Assay, and an innovative ELISA with IgY-antibodies extracted from eggs of NRL-immunized hens (IgY Inhibition Assay). We found a high protein content in a range of 215.0-1304.7 μg/g in 8 out of the 20 NRL gloves. Seven of the 20 gloves were powdered, four of them with a high protein content. In gloves with high protein content, the immunological tests detected congruently high levels of NRL allergen. We conclude that a high percentage of commercially available NRL gloves still represent a risk for NRL allergy, including asthma. The modified Lowry Method allows to infer on the latex allergen content. PMID:27241513

  3. Large-size monodisperse latexes as a commercial space product

    NASA Technical Reports Server (NTRS)

    Kornfeld, D. M.

    1977-01-01

    Proposed spacelab production of large-size (2-40 micron diameter) monodispersed latexes is discussed. Explanations are given for the present lack of monodisperse particles in this size range. The four main topics discussed are: (1) the potential uses of these large particle size latexes, (2) why it is necessary for the particles to have a very narrow size distribution, (3) why large amounts of these monodisperse latexes are needed, and (4) why it is necessary to go to microgravity to prepare these latexes.

  4. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1990-03-13

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  5. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1988-05-26

    A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

  6. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  7. A COMPARISON OF THE ROSE-WAALER, LATEX FIXATION, "RA-TEST," AND BENTONITE FLOCCULATION TESTS.

    PubMed

    Greenbury, C L; Keningale, J

    1960-07-01

    The bentonite flocculation test of Bozicevich, Bunim, Freund, and Ward (1958), the latex fixation test of Singer and Plotz (1956), and the "RA-test" (a latex reagent for use as a slide test) of Hyland Laboratories have been compared with each other and with a modified Rose-Waaler test, the behaviour of which has been previously extensively investigated. In these tests sera from 2,250 patients were tested by two or more methods on 3,000 occasions. The findings of this trial are set out and the merits of the tests and reasons for disagreement among them are discussed. It is concluded that the most satisfactory means of testing rheumatoid sera is by the Rose-Waaler test and the "RA-test," or a satisfactory modification of it, in parallel.

  8. Gloves against mineral oils and mechanical hazards: composites of carboxylated acrylonitrile-butadiene rubber latex.

    PubMed

    Krzemińska, Sylwia; Rzymski, Władysław M; Malesa, Monika; Borkowska, Urszula; Oleksy, Mariusz

    2016-09-01

    Resistance to permeation of noxious chemical substances should be accompanied by resistance to mechanical factors because the glove material may be torn, cut or punctured in the workplace. This study reports on glove materials, protecting against mineral oils and mechanical hazards, made of carboxylated acrylonitrile-butadiene rubber (XNBR) latex. The obtained materials were characterized by a very high resistance of the produced materials to oil permeation (breakthrough time > 480 min). The mechanical properties, and especially tear resistance, of the studied materials were improved after the addition of modified bentonite (nanofiller) to the XNBR latex mixture. The nanocomposite meets the requirements in terms of parameters characterizing tear, abrasion, cut and puncture resistance. Therefore, the developed material may be used for the production of multifunctional protective gloves. PMID:26757889

  9. Gloves against mineral oils and mechanical hazards: composites of carboxylated acrylonitrile–butadiene rubber latex

    PubMed Central

    Krzemińska, Sylwia; Rzymski, Władysław M.; Malesa, Monika; Borkowska, Urszula; Oleksy, Mariusz

    2016-01-01

    Resistance to permeation of noxious chemical substances should be accompanied by resistance to mechanical factors because the glove material may be torn, cut or punctured in the workplace. This study reports on glove materials, protecting against mineral oils and mechanical hazards, made of carboxylated acrylonitrile–butadiene rubber (XNBR) latex. The obtained materials were characterized by a very high resistance of the produced materials to oil permeation (breakthrough time > 480 min). The mechanical properties, and especially tear resistance, of the studied materials were improved after the addition of modified bentonite (nanofiller) to the XNBR latex mixture. The nanocomposite meets the requirements in terms of parameters characterizing tear, abrasion, cut and puncture resistance. Therefore, the developed material may be used for the production of multifunctional protective gloves. PMID:26757889

  10. Bacterial concrete

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Venkataswamy; Ramesh, K. P.; Bang, S. S.

    2001-04-01

    Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self-repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii and Sporosarcina bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and CaCl2 medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places. Energy- dispersive X-ray (EDX) spectra of the microbial precipitation on the surface of the crack indicated the abundance of calcium and the precipitation was inferred to be calcite (CaCO3).

  11. 21 CFR 801.435 - User labeling for latex condoms.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false User labeling for latex condoms. 801.435 Section... latex condoms. (a) This section applies to the subset of condoms as identified in § 884.5300 of this chapter, and condoms with spermicidal lubricant as identified in § 884.5310 of this chapter,...

  12. 21 CFR 801.435 - User labeling for latex condoms.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false User labeling for latex condoms. 801.435 Section... latex condoms. (a) This section applies to the subset of condoms as identified in § 884.5300 of this chapter, and condoms with spermicidal lubricant as identified in § 884.5310 of this chapter,...

  13. 21 CFR 801.435 - User labeling for latex condoms.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false User labeling for latex condoms. 801.435 Section... latex condoms. (a) This section applies to the subset of condoms as identified in § 884.5300 of this chapter, and condoms with spermicidal lubricant as identified in § 884.5310 of this chapter,...

  14. 21 CFR 801.435 - User labeling for latex condoms.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false User labeling for latex condoms. 801.435 Section 801.435 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... spermicidal stability testing is different from the expiration date based upon latex integrity testing,...

  15. 21 CFR 801.435 - User labeling for latex condoms.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false User labeling for latex condoms. 801.435 Section 801.435 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... spermicidal stability testing is different from the expiration date based upon latex integrity testing,...

  16. New approach for papaya latex storage without virus degradation

    PubMed Central

    Rodrigues, Silas P.; Andrade, Josemar S.; Ventura, José A.; Fernandes, Patricia M. B.

    2009-01-01

    Papaya meleira virus (PMeV) is the causal agent of papaya (Carica papaya L.) sticky disease, which has been detected through analysis of its double-stranded RNA (dsRNA) genome from plant latex. In this work we demonstrate that PMeV dsRNA is protected during 25 days when latex is diluted in citrate buffer pH 5.0 (1:1 v/v) and maintained at -20ºC. At the same temperature, some protection was observed for pure latex or latex diluted in ultra-pure water. Conversely, the dsRNA was almost completely degraded after 25 days when maintained at 25ºC, indicating the need for freezing. The proper procedures to collect and store papaya latex described here will contribute to efficient and large scale use of molecular diagnosis of PMeV. PMID:24031329

  17. New approach for papaya latex storage without virus degradation.

    PubMed

    Rodrigues, Silas P; Andrade, Josemar S; Ventura, José A; Fernandes, Patricia M B

    2009-01-01

    Papaya meleira virus (PMeV) is the causal agent of papaya (Carica papaya L.) sticky disease, which has been detected through analysis of its double-stranded RNA (dsRNA) genome from plant latex. In this work we demonstrate that PMeV dsRNA is protected during 25 days when latex is diluted in citrate buffer pH 5.0 (1:1 v/v) and maintained at -20ºC. At the same temperature, some protection was observed for pure latex or latex diluted in ultra-pure water. Conversely, the dsRNA was almost completely degraded after 25 days when maintained at 25ºC, indicating the need for freezing. The proper procedures to collect and store papaya latex described here will contribute to efficient and large scale use of molecular diagnosis of PMeV.

  18. Coagulant and anticoagulant activities in Jatropha curcas latex.

    PubMed

    Osoniyi, Omolaja; Onajobi, Funmi

    2003-11-01

    Jatropha curcas Linn. (Euphorbiaceae), a medicinal plant commonly grown in the Tropics, is traditionally used as a haemostatic. Investigation of the coagulant activity of the latex of Jatropha curcas showed that whole latex significantly (P<0.01) reduced the clotting time of human blood. Diluted latex, however, prolonged the clotting time: at high dilutions, the blood did not clot at all. This indicates that Jatropha curcas latex possesses both procoagulant and anticoagulant activities. Prothrombin time (PT) and activated partial thromboplastin time (APTT) tests on plasma confirm these observations. Solvent partitioning of the latex with ethyl acetate and butanol led to a partial separation of the two opposing activities: at low concentrations, the ethyl acetate fraction exhibited a procoagulant activity, while the butanol fraction had the highest anticoagulant activity. The residual aqueous fraction had no significant effect on the clotting time of blood and the PT but slightly prolonged the APTT.

  19. Nuclear Power Plant Concrete Structures

    SciTech Connect

    Basu, Prabir; Labbe, Pierre; Naus, Dan

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  20. Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species1[W

    PubMed Central

    Wahler, Daniela; Gronover, Christian Schulze; Richter, Carolin; Foucu, Florence; Twyman, Richard M.; Moerschbacher, Bruno M.; Fischer, Rainer; Muth, Jost; Prüfer, Dirk

    2009-01-01

    Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenol-oxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution. PMID:19605551

  1. Evaluation of percutaneous penetration of natural rubber latex proteins.

    PubMed

    Hayes, B B; Afshari, A; Millecchia, L; Willard, P A; Povoski, S P; Meade, B J

    2000-08-01

    Latex allergy is recognized worldwide as a serious health risk. To date, exposure assessment and intervention strategies have focused primarily on respiratory protection; this work evaluates the potential role of dermal protein penetration in the development of latex allergy. In vitro penetration models using flow-through diffusion cells and both human surgical specimens and hairless guinea pig skin (CrL: IAF/HA) demonstrated iodinated latex proteins (ammoniated and non-ammoniated) penetrating into and through both intact and abraded skin. Although less than 1% penetration was observed with intact skin, up to 23% of latex proteins applied to abraded skin were recovered from receptor fluid within 24 h of exposure. Phosphoimaging of the concentrated effluent revealed proteins ranging in size from 3 to 26 kDa. Using a (3)H(2)O penetration assay to evaluate barrier integrity, the amount of latex protein penetration was found to positively correlate with the degree of dermabrasion. Immunohistochemistry of the skin localized latex proteins in the Langerhans cell-rich epidermis and in the dermis. Both in vitro penetration studies and immunohistochemistry supported the use of hairless guinea pig skin as a surrogate for human skin in evaluating latex protein penetration. In studies performed in vivo, 35% of hairless guinea pigs topically exposed to latex proteins (100 microg) 5 days per week for 3 months demonstrated elevations in latex-specific IgG1. The implication for these data is that the skin is not only a plausible route for latex sensitization but can be a major exposure route when the integument has been compromised. PMID:10910983

  2. Polyphenoloxidase silencing affects latex coagulation in Taraxacum species.

    PubMed

    Wahler, Daniela; Gronover, Christian Schulze; Richter, Carolin; Foucu, Florence; Twyman, Richard M; Moerschbacher, Bruno M; Fischer, Rainer; Muth, Jost; Prüfer, Dirk

    2009-09-01

    Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenol-oxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution.

  3. Risk factors for latex sensitization among health care workers.

    PubMed

    Vila, L; Sánchez, G; Añó, M; Uasuf, C G; Sanz, M L

    1999-01-01

    Health care workers, children with spina bifida and rubber industry workers show higher prevalence of latex sensitization compared to the general population, and they are considered at-risk groups. Our aim was to establish the prevalence of latex allergy among health care workers at the Clínica Universitaria of Navarra and to analyze potential risk factors, including personal and family history of atopy, sex, as well as factors leading to enhanced exposure to latex, such as being a nurse, belonging to surgical departments, having undergone previous surgery and the number of gloves employed per week. Health care workers (n = 1,150) (doctors, nurses, assistant nurses, laboratory technicians and practicing medical and nursing students) were evaluated using a questionnaire and skin prick test (SPT). Serum specific IgE was determined by CAP-FEIA (Pharmacia, Sweden) in those with positive SPT. The participation index was 26.17%: 301 volunteers answered the questionnaire and underwent SPT. Fifteen subjects presented positive SPT to latex. It was found that 5% of the health care workers from the Clínica Universitaria were sensitized to latex allergens. Thirteen were females and two males. Mean age was 38.4 (+/- 7.09) years. Nine were nurses, three assistant nurses, one nursing student and two medical doctors. Eight belonged to medical, five to surgical and two to laboratory departments. There were no significant differences among the subjects in the prevalence of latex sensitization. Fourteen reported symptoms related to latex, mostly pruritus, dryness and/or redness of the hands (n = 12) and rhinitis (n = 6). Only one subject reported no symptoms when using latex products. Eight were atopic; personal history of atopy was the only significant (odds ratio = 5.10, p < 0.01) risk factor for latex sensitization. It was concluded that atopic health care workers show a more increased risk of latex sensitization than those who are nonatopic. PMID:10664929

  4. Modeling of composite latex particle morphology by off-lattice Monte Carlo simulation.

    PubMed

    Duda, Yurko; Vázquez, Flavio

    2005-02-01

    Composite latex particles have shown a great range of applications such as paint resins, varnishes, water borne adhesives, impact modifiers, etc. The high-performance properties of this kind of materials may be explained in terms of a synergistical combination of two different polymers (usually a rubber and a thermoplastic). A great variety of composite latex particles with very different morphologies may be obtained by two-step emulsion polymerization processes. The formation of specific particle morphology depends on the chemical and physical nature of the monomers used during the synthesis, the process temperature, the reaction initiator, the surfactants, etc. Only a few models have been proposed to explain the appearance of the composite particle morphologies. These models have been based on the change of the interfacial energies during the synthesis. In this work, we present a new three-component model: Polymer blend (flexible and rigid chain particles) is dispersed in water by forming spherical cavities. Monte Carlo simulations of the model in two dimensions are used to determine the density distribution of chains and water molecules inside the suspended particle. This approach allows us to study the dependence of the morphology of the composite latex particles on the relative hydrophilicity and flexibility of the chain molecules as well as on their density and composition. It has been shown that our simple model is capable of reproducing the main features of the various morphologies observed in synthesis experiments.

  5. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... latex foam subcategory. 428.110 Section 428.110 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Latex Foam Subcategory § 428.110 Applicability; description of the latex foam subcategory. The... latex foam except for those discharges from textile plants subject to the provisions of part 410 of...

  6. Size effects of latex nanomaterials on lung inflammation in mice

    SciTech Connect

    Inoue, Ken-ichiro Takano, Hirohisa; Yanagisawa, Rie; Koike, Eiko; Shimada, Akinori

    2009-01-01

    Effects of nano-sized materials (nanomaterials) on sensitive population have not been well elucidated. This study examined the effects of pulmonary exposure to (latex) nanomaterials on lung inflammation related to lipopolysaccharide (LPS) or allergen in mice, especially in terms of their size-dependency. In protocol 1, ICR male mice were divided into 8 experimental groups that intratracheally received a single exposure to vehicle, latex nanomaterials (250 {mu}g/animal) with three sizes (25, 50, and 100 nm), LPS (75 {mu}g/animal), or LPS plus latex nanomaterials. In protocol 2, ICR male mice were divided into 8 experimental groups that intratracheally received repeated exposure to vehicle, latex nanomaterials (100 {mu}g/animal), allergen (ovalbumin: OVA; 1 {mu}g/animal), or allergen plus latex nanomaterials. In protocol 1, latex nanomaterials with all sizes exacerbated lung inflammation elicited by LPS, showing an overall trend of amplified lung expressions of proinflammatory cytokines. Furthermore, LPS plus nanomaterials, especially with size less than 50 nm, significantly elevated circulatory levels of fibrinogen, macrophage chemoattractant protein-1, and keratinocyte-derived chemoattractant, and von Willebrand factor as compared with LPS alone. The enhancement tended overall to be greater with the smaller nanomaterials than with the larger ones. In protocol 2, latex nanomaterials with all sizes did not significantly enhance the pathophysiology of allergic asthma, characterized by eosinophilic lung inflammation and Igs production, although latex nanomaterials with less than 50 nm significantly induced/enhanced neutrophilic lung inflammation. These results suggest that latex nanomaterials differentially affect two types of (innate and adaptive immunity-dominant) lung inflammation.

  7. Epoxy coatings over latex block fillers

    SciTech Connect

    Vincent, L.D.

    1997-12-01

    Failures of polymerized epoxy coatings applied over latex/acrylic block fillers continue to plague owners of commercial buildings, particularly those with high architectural content such as condominiums, high rise offices, etc. Water treatment facilities in paper mills are especially prone to this problem. The types of failures include delamination of the topcoats, blisters in both the block fillers and the topcoats and disintegration of the block filler itself. While the problem is well known, the approach to a solution is not. A study of several coatings manufacturer`s Product Data Sheets shows a wide variance in the recommendations for what are purportedly generically equivalent block fillers. While one manufacturer might take an essentially architectural approach, another will take a heavy-duty industrial approach. To the specifying architect or engineer who has little training in the complexities of protective coating systems, this presents a dilemma. Who does he believe? What does he specify? To whom can he turn for independent advice?

  8. Contact Dermatitis (Including Latex Dermatitis) (Beyond the Basics)

    MedlinePlus

    ... Terms of Use ©2016 UpToDate, Inc. Patient education: Contact dermatitis (including latex dermatitis) (Beyond the Basics) Authors ... defined as an inflammation of the skin [ 1 ]. Contact dermatitis refers to dermatitis that is caused by ...

  9. Performance of latex balloons for optical computed tomography

    NASA Astrophysics Data System (ADS)

    Jordan, K.; Walsh, A.; Peng, M.; Battista, J.

    2013-06-01

    Latex balloons filled with radiation sensitive hydrogels were evaluated as 3D dosimeters with optical computed tomography (CT) readout. Custom balloons, with less than 10 cm diameters, were made from latex sheets. Commercial, 13 cm diameter, clear balloons were investigated for larger volumes. Ferrous-xylenol orange and genipin gelatin gels selected for 1 and 30 Gy experiments, respectively. The thin stretched latex membrane allowed optical imaging to within 1 mm of the interior balloon edge. Reconstructed dose distributions demonstrated valid measurements to within 2 mm of the balloon surface. The rubber membrane provides a hybrid approach to deforming hydrogels. Uniform irradiation of a deformed gel resulted in a uniform dose being measured when scanned in the relaxed, initial balloon shape. The 13 cm diameter balloons were also effective and inexpensive vessels for hydrogels due to their high clarity, thinness and mechanical strength. Latex balloons represent an inexpensive method to obtain useful information from nearly the entire dosimeter volume.

  10. Phorbic Acid Biosynthesis in the Latex Vessel System of Euphorbia

    PubMed Central

    Nordal, Arnold; Benson, A. A.

    1969-01-01

    Evidence is presented that phorbic acid is formed in the latex producing cell system, rather than in photosynthetic or chlorophyll-free tissues of Euphorbia resinifera Berg. When a branch of the plant was kept first in a 14CO2 atmosphere with 12 hr light-dark periods for 2 days and then left under natural conditions in the air outside for at least 2 to 3 days, radioactive phorbic acid was found in the latex. Phorbic acid synthesis appeared to be independent of the photosynthetic and respiratory activities of the plant. Besides phorbic acid 2 other major radioactive compounds were recognized in the latex, a glycoside or oligosaccharide, and a lipid belonging to the group of triterpenoid compounds characteristic of the latex in several species of Euphorbia. Images PMID:16657036

  11. The prevalence of latex allergy in operating theatre staff.

    PubMed

    Hack, M E

    2001-02-01

    Latex allergy has become increasingly common amongst health care workers. The prevalence of latex allergy in 102 theatre personnel at Princess Alexandra Hospital was determined by the results of a standardized questionnaire and a latex specific IgE radioallergosorbent test (RAST). Volunteers had their forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) measured at the beginning and end of their working shifts. Only one of 102 volunteers had a positive latex specific IgE RAST and he also experienced both local and systemic symptoms with latex exposure and a deterioration in daily FEV1/FVC. The 14 volunteers using asthma medications had significantly higher incidence of operating theatre symptoms (10/14), local reactions (8/14), and atopy (14/14). There was no clinically significant daily change in FEV1 in the total population or any specific group. The 1% (1/102) prevalence of latex allergy and sensitization in theatre staff demonstrates a much lower incidence than previously reported (12.5%, 15.8%).

  12. Immune response modulation by curcumin in a latex allergy model

    PubMed Central

    Kurup, Viswanath P; Barrios, Christy S; Raju, Raghavan; Johnson, Bryon D; Levy, Michael B; Fink, Jordan N

    2007-01-01

    Background There has been a worldwide increase in allergy and asthma over the last few decades, particularly in industrially developed nations. This resulted in a renewed interest to understand the pathogenesis of allergy in recent years. The progress made in the pathogenesis of allergic disease has led to the exploration of novel alternative therapies, which include herbal medicines as well. Curcumin, present in turmeric, a frequently used spice in Asia has been shown to have anti-allergic and inflammatory potential. Methods We used a murine model of latex allergy to investigate the role of curcumin as an immunomodulator. BALB/c mice were exposed to latex allergens and developed latex allergy with a Th2 type of immune response. These animals were treated with curcumin and the immunological and inflammatory responses were evaluated. Results Animals exposed to latex showed enhanced serum IgE, latex specific IgG1, IL-4, IL-5, IL-13, eosinophils and inflammation in the lungs. Intragastric treatment of latex-sensitized mice with curcumin demonstrated a diminished Th2 response with a concurrent reduction in lung inflammation. Eosinophilia in curcumin-treated mice was markedly reduced, co-stimulatory molecule expression (CD80, CD86, and OX40L) on antigen-presenting cells was decreased, and expression of MMP-9, OAT, and TSLP genes was also attenuated. Conclusion These results suggest that curcumin has potential therapeutic value for controlling allergic responses resulting from exposure to allergens. PMID:17254346

  13. Troubleshooting for the observed problems in processing latex concentrate from natural resource

    NASA Astrophysics Data System (ADS)

    Afreen, S.; Haque, K. R.; Huda, M. K.

    2013-06-01

    Natural latex has special importance in the rubber industry for manufacturing different types of goods like gloves, balloons, male contraceptive and similar thin walled articles. This natural latex is much more sensitive a liquid to handle since it can easily become contaminated and thereby coagulated which makes it unfavourable for centrifuge and getting concentrate from it. Some other related measures also are included in consideration during the processing of concentrate latex from the natural raw latex. The problems that are being faced in a concentrate latex processing plant can be categorized in different groups like, problems related to the latex property, mechanical problems, electrical problems, handling and storage problems, transformation problems, problems related to environmental issues, etc. Among them, the most common and vital problems frequently observed in a concentrate latex processing plant are discussed here with a view to finding the measures for solution which will help to maintain the latex property in any latex processing plant.

  14. Latex glove use by food handlers: the case for nonlatex gloves.

    PubMed

    Ameratunga, Rohan; Ameratunga, Shanthi; Crooks, Christine; Simmons, Greg

    2008-11-01

    There is increasing concern that continued exposure to latex products can predispose individuals, particularly those who are atopic (allergy prone), to latex allergy. Latex allergy as a serious hazard has been well documented in the health care industry. There are also well-documented cases of food handlers who have had allergic reactions after the use of latex gloves. The contamination of food with latex proteins by food handlers using latex gloves can also result in potentially severe allergic reactions in latex-allergic consumers. We review latex allergy and present the case for avoiding latex glove use by food handlers in the food and hospitality industries. Adopting the use of nonlatex gloves has benefits for workers, consumers, and the food industry. PMID:19044282

  15. Hevea latex lectin binding protein in C-serum as an anti-latex coagulating factor and its role in a proposed new model for latex coagulation.

    PubMed

    Wititsuwannakul, Rapepun; Pasitkul, Piyaporn; Jewtragoon, Pattavuth; Wititsuwannakul, Dhirayos

    2008-02-01

    A distinct protein specifically recognized by its strong interaction with Hevea latex lectin (HLL) was detected in the aqueous C-serum fraction of centrifuged fresh latex. This C-serum lectin binding protein (CS-HLLBP) exhibited strong inhibition of HLL-induced hemagglutination. The CS-HLLBP was purified to homogeneity by a protocol that included ammonium sulfate fractionation, size exclusion and ion exchange chromatography. The purified CS-HLLBP had a specific HI titer of 0.23microg ml(-1). Its M(r)s analyzed by SDS-PAGE was ca. 40kDa and that by gel filtration was ca. 204kDa. It has a pI value of 4.7, an optimum activity between pH 6 and10 and was heat stable up to 50 degrees C. The HI activity of CS-HLLBP was abolished upon treatment with chitinase. The CS-HLLBP inhibited HLL-induced rubber particle aggregation in a dose dependent manner. A highly positive correlation between CS-HLLBP activity and rubber yield per tapping was found. The correlations for fresh latex (r=0.98, P<0.01) and dry rubber (r=0.95, P<0.01) were both highly significant. This indicated that the CS-HLLBP might be used as a reliable marker for the mass screening of young seedlings to identify and select clones with potential to be superior producers of rubber. A latex anti-coagulating role of the CS-HLLBP is proposed. The findings described in this 3 paper series have been used to propose a new model of rubber latex coagulation that logically describes roles for the newly characterized latex lectin and the two lectin binding proteins. PMID:17983633

  16. Synthesis and engineering of polymeric latex particles for medical applications

    NASA Astrophysics Data System (ADS)

    Kim, Sangyup

    Latex particles with well-defined colloidal and surface characteristics have received increasing attention due to their useful applications in many areas, especially as solid phase supports in numerous biological applications such as immunoassay, DNA diagnostic, cell separation, and drug delivery carrier. Hemodialysis membrane using these particles would be another potential application for the advanced separation treatment for patients with end stage renal disease (ESRD). It is desirable to remove middle molecular weight proteins with minimal removal of other proteins such as albumin. Thus, it is necessary to understand the fundamental interactions between the particles and blood proteins to maximize the performance of these membranes. This improvement will have significant economic and health impact. The objective of this study is to synthesize polymeric latex particles of specific functionality to achieve the desired selective separation of target proteins from the human blood. Semi-continuous seed emulsion polymerization was used to prepare monodisperse polystyrene seed particles ranging from 126+/-7.5 to 216+/-5.3 nm in size, which are then enlarged by about 800nm. Surfactant amount played a key role in controlling the latex particle size. Negatively charged latex particles with a different hydrophobicity were prepared by introduction of a sodium persulfate initiator and hydrophilic acrylic acid monomer. The prepared polymeric particles include bare polystyrene (PS) particles, less hydrophobic PS core and PMMA shell particles, and more hydrophilic PS core and PMMA-co-PAA shell latex particles with a 370nm mean diameter. SEM, light scattering, and zeta potential measurements were used to characterize particle size and surface properties. Adsorption isotherms of two proteins, bovine serum albumin (BSA) and beta2-microglobulin (beta2M), on latex particles were obtained as a function of pH and ionic strength using the bicinchoninic acid (BCA) assay method. The

  17. Xyloglucan-Functional Latex Particles via RAFT-Mediated Emulsion Polymerization for the Biomimetic Modification of Cellulose.

    PubMed

    Hatton, Fiona L; Ruda, Marcus; Lansalot, Muriel; D'Agosto, Franck; Malmström, Eva; Carlmark, Anna

    2016-04-11

    Herein, we report a novel class of latex particles composed of a hemicellulose, xyloglucan (XG), and poly(methyl methacrylate) (PMMA), specially designed to enable a biomimetic modification of cellulose. The formation of the latex particles was achieved utilizing reversible addition-fragmentation chain transfer (RAFT) mediated surfactant-free emulsion polymerization employing XG as a hydrophilic macromolecular RAFT agent (macroRAFT). In an initial step, XG was functionalized at the reducing chain end to bear a dithioester. This XG macroRAFT was subsequently utilized in water and chain extended with methyl methacrylate (MMA) as hydrophobic monomer, inspired by a polymerization-induced self-assembly (PISA) process. This yielded latex nanoparticles with a hydrophobic PMMA core stabilized by the hydrophilic XG chains at the corona. The molar mass of PMMA targeted was varied, resulting in a series of stable latex particles with hydrophobic PMMA content between 22 and 68 wt % of the total solids content (5-10%). The XG-PMMA nanoparticles were subsequently adsorbed to a neutral cellulose substrate (filter paper), and the modified surfaces were analyzed by FT-IR and SEM analyses. The adsorption of the latex particles was also investigated by quartz crystal microbalance with dissipation monitoring (QCM-D), where the nanoparticles were adsorbed to negatively charged model cellulose surfaces. The surfaces were analyzed by atomic force microscopy (AFM) and contact angle (CA) measurements. QCM-D experiments showed that more mass was adsorbed to the surfaces with increasing molar mass of the PMMA present. AFM of the surfaces after adsorption showed discrete particles, which were no longer present after annealing (160 °C, 1 h) and the roughness (Rq) of the surfaces had also decreased by at least half. Interestingly, after annealing, the surfaces did not all become more hydrophobic, as monitored by CA measurements, indicating that the surface roughness was an important factor to

  18. Occupational asthma caused by natural rubber latex.

    PubMed

    Vandenplas, O

    1995-11-01

    IgE-mediated sensitization in protein allergens of natural rubber latex (NRL) can induce immediate hypersensitivity reactions ranging from mild urticaria in life threatening anaphylaxis after cutaneous, mucosal or visceral exposure. Elutable allergens from NRL gloves absorb to the cornstarch powder particles, become airborne, and have the potential to cause respiratory reactions. Recent studies indicate that asthma is a frequent manifestation of NRL allergy among workers manufacturing NRL materials and among health-care providers using NRL workers. NRL-induced asthma should receive increasing attention as it can lead to permanent respiratory sequelae and occupational disability. The need for early and accurate diagnosis is outlined and the different diagnostic approaches are reviewed. Specific issues pertaining to the management of affected subjects and to the prevention of exposure to airborne NRL are discussed. Ares of future research should include: 1) further characterization of relevant NRL allergens; 2) development and validation of methods for quantitative assessment of allergen content in NRL devices and workplace environment; 3) evaluation of the natural history and risk factors of NRL-induced asthma; and 5) analysis of effectiveness and cost of preventive strategies. PMID:8620969

  19. Latex elastomer with a permanently hydrophilic surface

    NASA Astrophysics Data System (ADS)

    Noda, Isao

    1991-03-01

    WATER wettability is important in many applications of polymeric materials, including fabrics, printing and biomedical uses1,2. Various surface-modification techniques are available to convert the intrinsically hydrophobic surfaces of plastic to water-wettable ones, by incorporating chemically polar functional groups at the surface4-7. Although such chemically induced surface hydrophilicity can be relatively long-lived while the substrates remain rigid, increases in the mobility of surface molecules, for example, due to increasing temperature, can cause rapid loss of hydrophilicity, driven by the tendency of surfaces to minimize their free energy2-5. As the polar groups are not often bound to the polymer matrix (usually being instead free surfactant molecules), they may also be flushed from the surface by repeated exposure to water. Here I report the preparation of permanently water-wettable elastomeric films from a latex synthesized by polymerization of monomers in the presence of an amphiphilic block copolymer. By migration of the hydrophilic segments to the surface during film formation, the film is rendered essentially completely wettable by water. Applications may include flexible coatings that can introduce spatially selective wettability to solid surfaces, for example one-side wettable perforated films used for bandages and disposable diapers8.

  20. Latex-less opium poppy: cause for less latex and reduced peduncle strength.

    PubMed

    Chaturvedi, Nidarshana; Singh, Sharad K; Shukla, Ashutosh K; Lal, Raj K; Gupta, Madan M; Dwivedi, Upendra N; Shasany, Ajit K

    2014-03-01

    A genotype 'Sujata' developed earlier at CSIR-CIMAP from its parent 'Sampada' is considered to be the latex-less variety of Papaver somniferum. These two genotypes are contrasting in terms of latex and stem strength. Earlier we have carried out microarray analysis to identify differentially expressing genes from the capsules of the two genotypes. In this study, the peduncles of the two genotypes were compared for the anatomy revealing less number of laticifers in the cortex and vascular bundles. One of the important cell wall-related genes (for laccase) from the microarray analysis showing significantly higher expression in 'Sampada' capsule was taken up for further characterization in the peduncle here. It was functionally characterized through transient overexpression and RNAi suppression in 'Sujata' and 'Sampada'. The increase in acid insoluble lignin and total lignin in overexpressed tissue of 'Sujata', and comparable decrease in suppressed tissue of 'Sampada', along with corresponding increase and decrease in the transcript abundance of laccase confirm the involvement of laccase in lignin biosynthesis. Negligible transcript in phloem compared to the xylem tissue localized its expression in xylem tissue. This demonstrates the involvement of P. somniferum laccase in lignin biosynthesis of xylem, providing strength to the peduncle/stem and preventing lodging.

  1. Refractory concretes

    DOEpatents

    Holcombe, Jr., Cressie E.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 with an aqueous solution of a salt selected from the group of NH.sub.4 NO.sub.3, NH.sub.4 Cl, YCl.sub.3 and Mg(NO.sub.3).sub.2 to form a fluid mixture; and allowing the fluid mixture to harden.

  2. Characterization of the proteolytic system present in Vasconcellea quercifolia latex.

    PubMed

    Torres, María José; Trejo, Sebastián Alejandro; Obregón, Walter David; Avilés, Francesc Xavier; López, Laura María Isabel; Natalucci, Claudia Luisa

    2012-11-01

    Vasconcellea quercifolia (Caricaceae) latex contains several cysteine endopeptidases with high proteolytic activity. Cysteine endopeptidases are the main active compounds used by the plant as a defense mechanism. A proteolytic preparation from V. quercifolia ("oak leaved papaya") latex was purified by cation exchange chromatography. From SDS-PAGE and blotting of the selected fractions, the N-terminal amino acid sequences of polypeptides were determined by Edman's degradation. The analysis by peptide mass fingerprinting (PMF) of the enzymes allowed their characterization and confirmed the presence of seven different cysteine proteinases in the latex of V. quercifolia. Moreover, the comparison between the tryptic maps with those deposited in databases using the MASCOT tool showed that none of the isolated proteases matched with another plant protease. Notably, a propeptidase was detected in the plant latex, which is being the first report in this sense. Furthermore, the cDNA of one of the cysteine proteases that is expressed in the latex of V. quercifolia was cloned and sequenced. The consensus sequence was aligned using the ClustalX web server, which allowed detecting a high degree of identity with cysteine proteases of the Caricaceae family and establishing the evolutionary relationship between them. We also observed a high conservation degree for those amino acid residues which are essential for the catalytic activity and tridimensional structure of the plant proteases belonging to the subfamily C1A. The PMF analysis strongly suggests that the sequence obtained corresponds to the VQ-III peptidase.

  3. Prevalence of food allergy in 137 latex-allergic patients.

    PubMed

    Kim, K T; Hussain, H

    1999-01-01

    There have been reports of increased prevalence of certain food allergies in patients with Type I latex allergy (LA). A detailed food allergy history was obtained from 137 patients with LA. Latex allergy was defined by positive history of IgE mediated reactions to contact with latex and positive skin prick test to latex and/or positive in vitro test (AlaSTAT and/or Pharmacia CAP). Food allergy was diagnosed by a convincing history of possible IgE mediated symptoms occurring within 60 minutes of ingestion. We identified 49 potential allergic reactions to foods in 29 (21.1%) patients. Foods responsible for these reactions include banana 9 (18.3%), avocado 8 (16.3%), shellfish 6 (12.2%), fish 4 (8.1%), kiwi 6 (12.2%), tomato 3 (6.1%), watermelon, peach, carrot 2 (4.1%) each, and apple, chestnut, cherry, coconut, apricot, strawberry, loquat, one (2.0%) each. Reactions to foods included local mouth irritation, angioedema, urticaria, asthma, nausea, vomiting, diarrhea, rhinitis, or anaphylaxis. Our study confirms the earlier reports of increased prevalence of food allergies in patients with LA. We also report increased prevalence of shellfish and fish allergy not previously reported. The nature of cross reacting epitopes or independent sensitization between latex and these foods is not clear.

  4. Foam concrete with porous mineral and organic additives

    NASA Astrophysics Data System (ADS)

    Kudiakov, A.; Prischepa, I.; Tolchennickov, M.

    2015-01-01

    The article presents results of studies of structural heat insulating foam concrete with porous mineral and organic additives. By mixing additives with the concrete the speed of the initial structure formation increases. The additives of ash loss and thermal-modified peat TMT 600 provide a stable increase of strength by compression and bending of foam concrete. In the dried foam concrete with the addition of TMT and ash loss thermal conductivity decreases by 20% and 7% respectively. The regularities of changes in the thermal conductivity at various moisture of foam concrete have been investigated.

  5. Caprine herpesvirus 1 (CpHV-1) vaginal infection of goats: clinical efficacy of fig latex.

    PubMed

    Camero, Michele; Marinaro, Mariarosaria; Losurdo, Michele; Larocca, Vittorio; Bodnar, Livia; Patruno, Giovanni; Buonavoglia, Canio; Tempesta, Maria

    2016-01-01

    The latex of Ficus carica Linn. (Moraceae) has been shown to interfere with the replication of caprine herpesvirus (CpHV)-1 in vitro. The present study was undertaken to determine the efficacy of vaginal administration of fig latex in goats experimentally infected with CpHV-1. The fig latex reduced the clinical signs of the herpetic disease although it slightly influenced the titres of CpHV-1 shed. Thus, the fig latex maintained a partial efficacy in vivo.

  6. Uranium (VI) and Neptunium (V) Transport Fractured, Hydrothermally Altered Concrete

    SciTech Connect

    Matzen, S.L.; Beiriger, J.M.; Torretto, P.C.; Zhao, P.

    1999-11-04

    In a high level waste repository in which temperatures are elevated due to waste decay, concrete structures will be subjected to hydrothermal conditions that will alter their physical and chemical properties. Virtually no studies have examined the interaction of hydrothermally altered concrete with radionuclides. We present the results of experiments in which soluble and colloid-associated actinides, uranium (U) and neptunium (Np), were eluted into a fractured, hydrothermally altered concrete core. Although the fluid residence time in the fracture was estimated to be on the order of 1 minute, U and Np were below detection (10{sup -9}-10{sup -8} M) in the effluent from the core, for both soluble and colloid-associated species. Inorganic colloids and latex microspheres were similarly immobilized within the core. Post-test analysis of the core identified the immobilized U and Np at or near the fracture surface, with a spatial distribution similar to that of the latex microspheres. Because hydrothermal alteration followed fracturing, the growth of crystalline calcium silicate hydrate and clay mineral alteration products on, and possibly across the fracture, resulted in a highly reactive fracture that was effective at capturing both soluble and colloidal radionuclides. Comparison of results from batch experiments [1] with these experiments indicate that partitioning of U and Np to the solid phase, and equilibration of the incoming fluid with the concrete, occurs rapidly in the fractured system. Transport of U through the concrete may be solubility and/or sorption limited; transport of Np appears to be limited primarily by sorption.

  7. Anaphylactic reactions during anaesthesia: neuromuscular blocking agents, latex and antibiotics.

    PubMed

    2013-05-01

    A French team investigated hypersensitivity reactions that occurred during locoregional or general anaesthesia over an 8-year period. They estimated that the incidence of anaphylactic reactions was about 1 per 10 000 anaesthetic procedures. Among the 1816 reports of anaphylactic reactions, the most commonly implicated drugs were neuromuscular blocking agents (1067 cases), latex (361 cases), and antibiotics (236 cases). Some anaphylactic reactions to neuromuscular blocking agents occurred in patients who had never previously been anaesthetised, suggesting cross-reactivity with other, poorly known, substances. Most reactions in children were due to latex, followed by neuromuscular blocking agents and antibiotics. In practice, exposure to latex devices should be minimised, or simply avoided when possible. A history of sensitization to substances sharing allergenic sites with neuromuscular blocking agents should be investigated, and measures should be taken to protect patients.

  8. Prevalence of latex hypersensitivity among health care workers in Malaysia.

    PubMed

    Shahnaz, M; Azizah, M R; Hasma, H; Mok, K L; Yip, E; Ganesapillai, T; Suraiya, H; Nasuruddin, B A

    1999-03-01

    Health care workers have been reported to constitute one of the few high-risk groups related to IgE-mediated hypersensitivity associated with the use of latex products. This paper describes the first ever study of prevalence carried out in Malaysia among these workers. One hundred and thirty health care personnel from Hospital Kuala Lumpur were skin tested. Extracts used were prepared from seven different brands of natural rubber latex gloves with varying levels of extractable protein (EPRRIM). Out of the 130 volunteers, 4 (3.1%) had positive skin test to latex with extracts with high levels of EPRRIM (> 0.7 mg/g). The prevalence among the Malaysian health care workers can be considered to be low in comparison to that of some consumer countries as the USA which reported a prevalence of as high as 16.9%.

  9. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... latex foam subcategory. 428.110 Section 428.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Foam Subcategory § 428.110 Applicability; description of the latex foam subcategory. The provisions...

  10. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... latex foam subcategory. 428.110 Section 428.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Foam Subcategory § 428.110 Applicability; description of the latex foam subcategory. The provisions...

  11. 40 CFR 428.40 - Applicability; description of the latex rubber subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... latex rubber subcategory. 428.40 Section 428.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Rubber Subcategory § 428.40 Applicability; description of the latex rubber subcategory....

  12. 40 CFR 428.40 - Applicability; description of the latex rubber subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... latex rubber subcategory. 428.40 Section 428.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Rubber Subcategory § 428.40 Applicability; description of the latex rubber subcategory....

  13. 40 CFR 428.40 - Applicability; description of the latex rubber subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... latex rubber subcategory. 428.40 Section 428.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Rubber Subcategory § 428.40 Applicability; description of the latex rubber subcategory....

  14. 40 CFR 428.40 - Applicability; description of the latex rubber subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... latex rubber subcategory. 428.40 Section 428.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Rubber Subcategory § 428.40 Applicability; description of the latex rubber subcategory. The provisions...

  15. 40 CFR 428.40 - Applicability; description of the latex rubber subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... latex rubber subcategory. 428.40 Section 428.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex Rubber Subcategory § 428.40 Applicability; description of the latex rubber subcategory. The provisions...

  16. POST-HARVEST STORAGE EFFECTS ON GUAYULE LATEX, RUBBER, AND RESIN CONTENTS AND YIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule is a new crop being commercialized for hypoallergenic latex production. Since natural processes that occur in the plant following harvest result in loss of latex almost immediately and immediate processing of guayule shrub for latex on a commercial scale is not feasible, a storage system tha...

  17. Reduction of use of latex gloves in food handlers: an intervention study.

    PubMed

    Lee, A; Nixon, R; Frowen, K

    2001-02-01

    Frequent latex glove use is a risk factor for the development of latex allergy. With the increase in latex glove use, latex allergy has become more prevalent. There are a number of occupational groups in which the use of latex gloves is both inappropriate and even hazardous, including food handlers, where the hazard relates particularly to their latex-sensitive customers. The aim of this study was to assess both the use of latex gloves by food handlers and the impact of an intervention study on reducing latex glove use. This was done at the Queen Victoria Market in Melbourne, Australia. We found that 10 out of 30 stalls (33%) used latex gloves, and that following a short education program, this was reduced to 1 stall (3%, p=0.006). The potential to reduce latex glove use by using this intervention study was 93% (95% confidence interval of 54%-100%). We recommend that food handlers be educated during their training, not only about hygiene issues, but also about the appropriate type of glove to wear, in order to prevent both the development of a new occupational group at risk of becoming allergic to latex, but more importantly to protect their latex-sensitive customers. PMID:11205407

  18. Evolving stresses in latex films as a function of temperature.

    PubMed

    Yow, Huai Nyin; Beristain, Itxaso; Goikoetxea, Monika; Barandiaran, Maria J; Routh, Alexander F

    2010-05-01

    Latex films were dried on a flexible substrate, and the substrate deflection was monitored over time to give an averaged film stress-evolution profile. Films were dried at various temperatures below and above the minimum film-formation temperature of the latex dispersion. The effect of polymer rheology, which is a temperature-dependent parameter, on film formation, was investigated. The reliability of the Stoney model in predicting film stress from substrate curvature was also examined and compared to the Euler-Bernoulli model. It was shown that the linearized Stoney model was unsuitable for the larger measured stresses. PMID:20387802

  19. Radiation vulcanization of natural rubber latex with polyfunctional monomers

    SciTech Connect

    Makuuchi, K.; Hagiwara, M.

    1984-03-01

    Natural rubber latex was irradiated with ..gamma..-rays from Co-60 in the presence of polyfunctional monomers to accelerate crosslinking of rubber molecules. Hydrophobic monomers were more effective in accelerating the vulcanization than were hydrophilic monomers. This was ascribed to high solubility of hydrophobic monomers in rubber particles. Among the hydrophobic monomers, neopentylglycol dimethacrylate (NPG) exhibited the highest efficiency in accelerating the vulcanization. Advantages of using NPG are high colloidal stability of the irradiated latex and high thermal stability of dried rubber film.

  20. Determination of Optical Constants of Latex in Concentrated Suspensions

    NASA Astrophysics Data System (ADS)

    Khaĭrullina, A. Ya.; Oleĭnik, T. V.; Buĭ, L. M.

    2000-11-01

    The possibility of taking into account concentration effects in the determination of optical constants of latex in the visible and near IR regions of the spectrum is demonstrated, and the limits of applicability of the methods proposed for this purpose are determined. The limiting concentration of particles in suspensions for which these effects should be taken into account depend on the particle size. Using latex as an example, ways of increasing the accuracy of reconstruction of optical constants of weakly absorbing particles of micron and submicron size are shown. Similar concentration effects can take place in the study of blood substituents, proteins, and other weakly absorbing particles in weakly absorbing media.

  1. Human fibrinogen adsorption on positively charged latex particles.

    PubMed

    Zeliszewska, Paulina; Bratek-Skicki, Anna; Adamczyk, Zbigniew; Cieśla, Michał

    2014-09-23

    Fibrinogen (Fb) adsorption on positively charged latex particles (average diameter of 800 nm) was studied using the microelectrophoretic and the concentration depletion methods based on AFM imaging. Monolayers on latex were adsorbed from diluted bulk solutions at pH 7.4 and an ionic strength in the range of 10(-3) to 0.15 M where fibrinogen molecules exhibited an average negative charge. The electrophoretic mobility of the latex after controlled fibrinogen adsorption was systematically measured. A monotonic decrease in the electrophoretic mobility of fibrinogen-covered latex was observed for all ionic strengths. The results of these experiments were interpreted according to the three-dimensional electrokinetic model. It was also determined using the concentration depletion method that fibrinogen adsorption was irreversible and the maximum coverage was equal to 0.6 mg m(-2) for ionic strength 10(-3) M and 1.3 mg m(-2) for ionic strength 0.15 M. The increase of the maximum coverage was confirmed by theoretical modeling based on the random sequential adsorption approach. Paradoxically, the maximum coverage of fibrinogen on positively charged latex particles was more than two times lower than the maximum coverage obtained for negative latex particles (3.2 mg m(-2)) at pH 7.4 and ionic strength of 0.15 M. This was interpreted as a result of the side-on adsorption of fibrinogen molecules with their negatively charged core attached to the positively charged latex surface. The stability and acid base properties of fibrinogen monolayers on latex were also determined in pH cycling experiments where it was observed that there were no irreversible conformational changes in the fibrinogen monolayers. Additionally, the zeta potential of monolayers was more positive than the zeta potential of fibrinogen in the bulk, which proves a heterogeneous charge distribution. These experimental data reveal a new, side-on adsorption mechanism of fibrinogen on positively charged surfaces and

  2. The effect of acrylic latex-based polymer on cow blood adhesive resins for wood composites

    NASA Astrophysics Data System (ADS)

    Yan, J.; Lin, H. L.; Feng, G. Z.; Gunasekaran, S.

    2016-07-01

    In this paper, alkali-modified cow blood adhesive (BA) and blood adhesive/acrylic latex-based adhesive (BA/ALB) were prepared. The physicochemical and adhesion properties of cow blood adhesive such as UV- visible spectra, particle size, viscosity were evaluated; share strength, water resistance were tested. UV- visible spectra indicates that the strong bonding strength of BA/ALB appeared after incorporating; the particle size of adhesive decreased with the increase of ALB concentration, by mixing ALB and BA, hydrophilic polymer tends locate or extand the protein chains and provide stability of the particles; viscosity decreased as shear rate increased in concordance with a pseudoplastic behavior; both at dry and soak conditions, BA and ALB/BA show significant difference changes when mass fraction of ALB in blend adhesive was over 30% (p < 0.05). ALB/ BA (ALB30%) is not significant different than that of phenol formaldehyde which was used as control. A combination of cow blood and acrylic latex-based adhesive significantly increased the strength and water resistance of the resulting wood.

  3. Sub-femtomolar electrochemical detection of DNA hybridization based on latex/gold nanoparticle-assisted signal amplification.

    PubMed

    Pinijsuwan, Suttiporn; Rijiravanich, Patsamon; Somasundrum, Mithran; Surareungchai, Werasak

    2008-09-01

    We report a relatively simple electrostatic method for modifying submicrometer-size latex spheres with gold nanoparticles (AuNPs) based on layer-by-layer modification of the latex by polyelectrolytes. The AuNP coverages for 343- and 501-nm-diameter spheres were 4.0 x 10 (10) +/- 1.3 x 10 (10) and 8.2 x 10 (10) +/- 2.7 x 10 (10) particles cm (-2), respectively, which is an increase of 1 order of magnitude on the previously reported coverage at latex-AuNPs using streptavidin-biotin binding (Kawde, A.N.; Wang, J. Electroanalysis 2004, 16, 101-107). Due to the fact that the AuNPs used here are also of a larger size (mean diameter 15.5 +/- 1.6 nm, cf. 5 nm), this represents an increase of 2 orders of magnitude in the number of Au atoms delivered per sphere. The spheres were attached to DNA probes specific to E. coli and used to detect probe hybridization by dissolution of the AuNPs, followed by measurement of Au (3+) ions by anodic stripping voltammetry (ASV). Use of differential pulse voltammetry for the stripping step, along with optimization of the ASV conditions, enabled a detection limit of 0.5 fM, which is, to the best of our knowledge, equal or lower than previous voltammetric nanoparticle methods for detection of DNA hybridization.

  4. The primary structure and characterization of carbohydrate chains of the extracellular glycoprotein proteinase inhibitor from latex of Carica papaya.

    PubMed

    Odani, S; Yokokawa, Y; Takeda, H; Abe, S; Odani, S

    1996-10-01

    A secretory proteinase inhibitor was isolated from the latex of green fruits of papaya (Carica papaya). The protein exhibited stoichiometric inhibition of bovine trypsin and alpha-chymotrypsin by the same site or overlapping binding sites. The complete covalent structure consisting of 184 amino acids and two disulfide bonds was determined by protein analysis. During the structural analysis, a procedure was established to separate very hydrophilic peptides by reverse-phase HPLC. The result revealed that the latex protein belongs to an extensively diverse plant protein family that includes inhibitors of serine, cysteine and aspartic proteases, a taste-modifying protein, wound responsive proteins, storage proteins, amylase inhibitors and even an oxidoreductase. In this superfamily, the latex proteinase inhibitor is most similar to the curious protein, miraculin, which makes sour food taste sweet. Two carbohydrate chains, each probably composed of (mannose)5, (xylose)1, (fucose)0-2, and (N-acetylglucosamine)2 residues, were attached to asparagine 84 and 90. Mass-spectrometric and compositional analysis suggested that they may represent a new class of plant xylose-containing carbohydrate chains with five mannose residues.

  5. Sulfonated macro-RAFT agents for the surfactant-free synthesis of cerium oxide-based hybrid latexes.

    PubMed

    Garnier, Jérôme; Warnant, Jérôme; Lacroix-Desmazes, Patrick; Dufils, Pierre-Emmanuel; Vinas, Jérôme; van Herk, Alex

    2013-10-01

    Three types of amphiphatic macro-RAFT agents were employed as compatibilizers to promote the polymerization reaction at the surface of nanoceria for the synthesis of CeO2-based hybrid latexes. Macro-RAFT copolymers and terpolymers were first synthesized employing various combinations of butyl acrylate as a hydrophobic monomer and acrylic acid (AA) and/or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as hydrophilic monomers. After characterizing the adsorption of these macro-RAFT agents at the cerium oxide surface by UV-visible spectrometry, emulsion copolymerization reactions of styrene and methyl acrylate were then carried out in the presence of the surface-modified nanoceria. Dynamic Light Scattering and cryo-Transmission Electron Microscopy were employed to confirm the hybrid structure of the final CeO2/polymer latexes, and proved that the presence of acrylic acid units in amphiphatic macro-RAFT agents enabled an efficient formation of hybrid structures, while the presence of AMPS units, when combined with AA units, resulted in a better distribution of cerium oxide nanoclusters between latex particles.

  6. The primary structure and characterization of carbohydrate chains of the extracellular glycoprotein proteinase inhibitor from latex of Carica papaya.

    PubMed

    Odani, S; Yokokawa, Y; Takeda, H; Abe, S; Odani, S

    1996-10-01

    A secretory proteinase inhibitor was isolated from the latex of green fruits of papaya (Carica papaya). The protein exhibited stoichiometric inhibition of bovine trypsin and alpha-chymotrypsin by the same site or overlapping binding sites. The complete covalent structure consisting of 184 amino acids and two disulfide bonds was determined by protein analysis. During the structural analysis, a procedure was established to separate very hydrophilic peptides by reverse-phase HPLC. The result revealed that the latex protein belongs to an extensively diverse plant protein family that includes inhibitors of serine, cysteine and aspartic proteases, a taste-modifying protein, wound responsive proteins, storage proteins, amylase inhibitors and even an oxidoreductase. In this superfamily, the latex proteinase inhibitor is most similar to the curious protein, miraculin, which makes sour food taste sweet. Two carbohydrate chains, each probably composed of (mannose)5, (xylose)1, (fucose)0-2, and (N-acetylglucosamine)2 residues, were attached to asparagine 84 and 90. Mass-spectrometric and compositional analysis suggested that they may represent a new class of plant xylose-containing carbohydrate chains with five mannose residues. PMID:8898891

  7. Better nirodhs now from Hindustan latex Ltd.

    PubMed

    1983-01-26

    On April 5, 1969, Hindustan Latex Limited (HLL), a Public Sector Enterprise under the Ministry of Health and Family Welfare of the Government of India, was established to produce "NIRODH"--condoms--for the nation's family planning program. The 1st factory for the manufacture of the male contraceptive was created at Trivandrum in Kerala State with Japanese collaboration. The production capacity at inception was 144 million pieces; this was doubled in 1977. From inception the company has manufactured nearly 2000 million pieces. The manufacture of condoms involves 4 main stages: compounding; moulding; vulcanizing; and electronic testing and inspection (quality control). Each of these stages of development is reviewed. HLL has achieved considerable progress and growth during the past year and recorded an all time high profit of Rs. 54.76 lakhs for 1981-82. Recently, the company delcared a 5% dividend on the paid up capital to be paid by India's government. This was possible because of the excellent working results the company achieved during the last year. During 1980-81 the company produced only 105.23 pieces of condoms. In 1981-82 the company produced 265.7 million pieces agianst the target set of 240 million pieces. For the excellent working performance of last year the company paid a good performance award to its employees apart from the minimum statutory bonus. The company has set a production target of 300 million pieces of condoms during 1982-82. HLL has planned for modernization of its 14-year old existing plant and machinery and for creating a new plant with installed capacity of 300 million pieces. The new plant is expected to be set up adjacent to the existing plant. The technical team has recommended the utilization of Japanese technology, one of the most advanced process technologies in the world for the manufacture of prophylactics, incorporating maximum automation and improvements in the process machinery. The new plant is expected to produce condoms of

  8. Peptidases and peptidase inhibitors in gut of caterpillars and in the latex of their host plants.

    PubMed

    Ramos, Márcio V; Pereira, Danielle A; Souza, Diego P; Silva, Maria-Lídia S; Alencar, Luciana M R; Sousa, Jeanlex S; Queiroz, Juliany-Fátima N; Freitas, Cleverson D T

    2015-01-01

    Studies investigating the resistance-susceptibility of crop insects to proteins found in latex fluids have been reported. However, latex-bearing plants also host insects. In this study, the gut proteolytic system of Pseudosphinx tetrio, which feeds on Plumeria rubra leaves, was characterized and further challenged against the latex proteolytic system of its own host plant and those of other latex-bearing plants. The gut proteolytic system of Danaus plexippus (monarch) and the latex proteolytic system of its host plant (Calotropis procera) were also studied. The latex proteins underwent extensive hydrolysis when mixed with the corresponding gut homogenates of the hosted insects. The gut homogenates partially digested the latex proteins of foreign plants. The fifth instar of D. plexippus that were fed diets containing foreign latex developed as well as those individuals who were fed diets containing latex proteins from their host plant. In vitro assays detected serine and cysteine peptidase inhibitors in both the gut homogenates and the latex fluids. Curiously, the peptidase inhibitors of caterpillars did not inhibit the latex peptidases of their host plants. However, the peptidase inhibitors of laticifer origin inhibited the proteolysis of gut homogenates. In vivo analyses of the peritrophic membrane proteins of D. plexippus demonstrate resistance against latex peptidases. Only discrete changes were observed when the peritrophic membrane was directly treated with purified latex peptidases in vitro. This study concludes that peptidase inhibitors are involved in the defensive systems of both caterpillars and their host plants. Although latex peptidase inhibitors inhibit gut peptidases (in vitro), the ability of gut peptidases to digest latex proteins (in vivo) regardless of their origin seems to be important in governing the resistance-susceptibility of caterpillars.

  9. Electrochemical impedance spectroscopy in chromatography paper and its application to latex bead detection

    NASA Astrophysics Data System (ADS)

    Iwahara, Shohei; Miki, Masashi; Hori, Fumitaka; Uno, Shigeyasu

    2014-01-01

    The principle of the quantitative immunochromatographic strip test (IST) is proposed. Electrochemical impedance spectroscopy is shown to be capable of detecting latex beads in chromatography paper, where latex beads can serve as a label in IST. Measurements to examine the impedance changes in the absence and presence of latex beads are conducted. In the presence of latex beads, an increase of 12.5% in the bulk solution resistance is observed. This indicates that the latex-bead-labeled antigen-antibody complex can be detected electrochemically by actual IST.

  10. [Occupational immediate allergy to latex. I. Introduction, epidemiology and clinical findings].

    PubMed

    Pałczyński, C; Walusiak, J

    1997-01-01

    For the 10 recent years the incidence of natural rubber latex (NRL) immediate allergy has dramatically increased. Allergy to latex is observed mostly among persons who regularly use rubber devices (particularly rubber gloves) or their mucous membrane is exposed to frequent contact with rubber products. The health service and the rubber industry workers are at the highest risk of latex allergy (10%). Urticaria, angioedema, bronchial asthma, conjunctivitis, rhinitis and anaphylactic shock are most common symptoms of allergy to latex. Severe systemic reactions are frequently first clinical manifestations of latex hypersensitivity. PMID:9312658

  11. Surface treated polypropylene (PP) fibres for reinforced concrete

    SciTech Connect

    López-Buendía, Angel M.; Romero-Sánchez, María Dolores; Climent, Verónica

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  12. The Use of Latex Gloves in the School Setting

    ERIC Educational Resources Information Center

    Purcell, Cathy Koeppen

    2006-01-01

    In 1987, when the U.S. Centers for Disease Control and Prevention recommended the use of universal precautions in response to the HIV/AIDS epidemic, the demand for medical gloves dramatically increased. Unfortunately, the manufacturing techniques for the most widely-used gloves--natural rubber latex--also changed, in order to expedite production.…

  13. Cutting height effects on guayule latex, rubber and resin yields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. While guayule traditionally has been cultivated for rubber, more recently it is being cultivated for its hypoallergenic latex. Other uses including termite resistant wood products and as an energy source have ...

  14. Production of large-particle-size monodisperse latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; El-Aasser, M. L.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.

    1984-01-01

    The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.

  15. Characterization of associated proteins and phospholipids in natural rubber latex.

    PubMed

    Sansatsadeekul, Jitlada; Sakdapipanich, Jitladda; Rojruthai, Porntip

    2011-06-01

    Non-rubber components present in natural rubber (NR) latex, such as proteins and phospholipids, are presumed to be distributed in the serum fraction as well as surrounding the rubber particle surface. The phospholipid-protein layers covering the rubber particle surface are especially interesting due to their ability to enhance the colloidal stability of NR latex. In this study, we have characterized the components surrounding the NR particle surface and investigated their role in the colloidal stability of NR particles. Proteins from the cream fraction were proteolytically removed from the NR latex and compare to those from the serum fractions using SDS-polyacrylamide gel electrophoresis revealing that both fractions contained similar proteins in certain molecular weights such as 14.5, 25 and 27 kDa. Phospholipids removed from latex by treatment with NaOH were analyzed using (1)H-NMR spectroscopy and several major signals were assignable to -(CH(2))(n)-, -CH(2)OP, -CH(2)OC═O and -OCH(2)CH(2)NH-. These signals are important evidence that indicates phospholipids associate with the rubber chain. The colloidal behavior of rubber lattices before and after removal of protein-lipid membrane was evaluated by zeta potential analysis and scanning electron microscope (SEM). The lowest zeta potential value of NR particles was observed at pH 10, consequently leading to the highest stability of rubber particles. Additionally, SEM micrographs clearly displayed a gray ring near the particle surface corresponding to the protein-lipid membrane layer.

  16. The formation of small scale granularities in latex particles

    NASA Technical Reports Server (NTRS)

    Zukoski, C. F.; Saville, D. A.

    1985-01-01

    A series of latices were synthesized using emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonic acid. The final latex particles display an internal granular structure which can be ascribed to the primary particles present in the early stages of particle growth. In these systems, the primary particles appear to have maintained their integrity during the swelling and growth stage.

  17. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  18. SUBSTRATE EFFECTS ON VOC EMISSIONS FROM A LATEX PAINT

    EPA Science Inventory

    The effects of two substrates -- a stainless steel plate and a gypsum board -- on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to...

  19. Tracking polymer diffusion in a wet latex film with fluorescence resonance energy transfer.

    PubMed

    Haley, Jeffrey C; Liu, Yuanqin; Winnik, Mitchell A; Demmer, David; Haslett, Tom; Lau, Willie

    2007-08-01

    We describe an instrument to measure the polymer interdiffusion between donor-labeled and acceptor-labeled latex polymers in a partially wet latex film with fluorescence resonance energy transfer (FRET). It is possible to temporarily arrest the drying process of a wet latex film by sealing the film in an airtight chamber. In our approach, we measure donor fluorescence decays from 0.5 mm diameter spots at various positions across an arrested latex film with time-correlated single photon counting. We interpret the resulting decays with a Monte Carlo simulation of the FRET process and extract information about the extent of polymer diffusion as a function of position on the film. These results enable us to determine the extent of polymer interdiffusion as a function of distance from the wet-dry edge in the latex film. To highlight this device's ability to capture the rapid early stages of latex interdiffusion, we report results from an acrylate copolymer latex.

  20. A novel arctigenin-containing latex glove prevents latex allergy by inhibiting type I/IV allergic reactions.

    PubMed

    Wang, Yong-Xin; Xue, Dan-Ting; Liu, Meng; Zhou, Zheng-Min; Shang, Jing

    2016-03-01

    The present study aimed at developing a natural compound with anti-allergic effect and stability under latex glove manufacturing conditions and investigating whether its anti-allergic effect is maintained after its addition into the latex. The effects of nine natural compounds on growth of the RBL-2H3 cells and mouse primary spleen lymphocytes were determined using MTT assay. The compounds included glycyrrhizin, osthole, tetrandrine, tea polyphenol, catechin, arctigenin, oleanolic acid, baicalin and oxymatrine. An ELISA assay was used for the in vitro anti-type I/IV allergy screening; in this process β-hexosaminidase, histamine, and IL-4 released from RBL-2H3 cell lines and IFN-γ and IL-2 released from mouse primary spleen lymphocytes were taken as screening indices. The physical stability of eight natural compounds and the dissolubility of arctigenin, selected based on the in vitro pharnacodynamaic screening and the stability evaluation, were detected by HPLC. The in vivo pharmacodynamic confirmation of arctigenin and final latex product was evaluated with a passive cutaneous anaphylaxis (PCA) model and an allergen-specific skin response model. Nine natural compounds showed minor growth inhibition on RBL-2H3 cells and mouse primary spleen lymphocytes. Baicalin and arctigenin had the best anti-type I and IV allergic effects among the natural compounds based on the in vitro pharmacodynamic screening. Arctigenin and catechin had the best physical stability under different manufacturing conditions. Arctigenin was the selected for further evaluation and proven to have anti-type I and IV allergic effects in vivo in a dose-dependent manner. The final product of the arctigenin-containing latex glove had anti-type I and IV allergic effects in vivo which were mainly attributed to arctigenin as proved from the dissolubility results. Arctigenin showed anti-type I and IV allergic effects in vitro and in vivo, with a good stability under latex glove manufacturing conditions

  1. A novel arctigenin-containing latex glove prevents latex allergy by inhibiting type I/IV allergic reactions.

    PubMed

    Wang, Yong-Xin; Xue, Dan-Ting; Liu, Meng; Zhou, Zheng-Min; Shang, Jing

    2016-03-01

    The present study aimed at developing a natural compound with anti-allergic effect and stability under latex glove manufacturing conditions and investigating whether its anti-allergic effect is maintained after its addition into the latex. The effects of nine natural compounds on growth of the RBL-2H3 cells and mouse primary spleen lymphocytes were determined using MTT assay. The compounds included glycyrrhizin, osthole, tetrandrine, tea polyphenol, catechin, arctigenin, oleanolic acid, baicalin and oxymatrine. An ELISA assay was used for the in vitro anti-type I/IV allergy screening; in this process β-hexosaminidase, histamine, and IL-4 released from RBL-2H3 cell lines and IFN-γ and IL-2 released from mouse primary spleen lymphocytes were taken as screening indices. The physical stability of eight natural compounds and the dissolubility of arctigenin, selected based on the in vitro pharnacodynamaic screening and the stability evaluation, were detected by HPLC. The in vivo pharmacodynamic confirmation of arctigenin and final latex product was evaluated with a passive cutaneous anaphylaxis (PCA) model and an allergen-specific skin response model. Nine natural compounds showed minor growth inhibition on RBL-2H3 cells and mouse primary spleen lymphocytes. Baicalin and arctigenin had the best anti-type I and IV allergic effects among the natural compounds based on the in vitro pharmacodynamic screening. Arctigenin and catechin had the best physical stability under different manufacturing conditions. Arctigenin was the selected for further evaluation and proven to have anti-type I and IV allergic effects in vivo in a dose-dependent manner. The final product of the arctigenin-containing latex glove had anti-type I and IV allergic effects in vivo which were mainly attributed to arctigenin as proved from the dissolubility results. Arctigenin showed anti-type I and IV allergic effects in vitro and in vivo, with a good stability under latex glove manufacturing conditions

  2. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1992-01-01

    Feasibility of using concrete for lunar base construction was discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the Moon are provided in this paper, along with specific conclusions from the existing database.

  3. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

  4. Comparison of genomic and antimicrobial resistance features of latex agglutination test-positive and latex agglutination test-negative Staphylococcus aureus isolates causing bovine mastitis.

    PubMed

    Moser, A; Stephan, R; Corti, S; Johler, S

    2013-01-01

    The dairy industry suffers massive economic losses due to staphylococcal mastitis in cattle. The Staphaureux latex agglutination test (Oxoid, Basel, Switzerland) was reported to lead to negative results in 54% of bovine Staphylococcus aureus strains, and latex-negative strains are thought to be less virulent than Staphaurex latex-positive strains. However, comparative information on virulence and resistance profiles of these 2 groups of Staph. aureus is scarce. Our objective was to associate the latex agglutination phenotype of Staph. aureus strains isolated from bovine mastitis milk with data on clonal complexes, virulence genes, and antibiotic resistance to (1) determine the virulence profiles of the Staphaureux test positive and Staphaurex test negative groups, and (2) provide data needed to improve treatment of bovine mastitis and to identify potential vaccine targets. Seventy-eight Staph. aureus strains isolated from 78 cows on 57 Swiss farms were characterized. Latex agglutination was tested by Staphaureux kit, and resistance profiles were generated by disk diffusion. A DNA microarray was used to assign clonal complexes (CC) and to determine virulence and resistance gene profiles. By the Staphaureux test, 49% of the isolates were latex-positive and 51% were latex-negative. All latex-negative strains were assigned to CC151, whereas latex-positive strains were assigned to various clonal complexes, including CC97 (n=16), CC8 (n=10), CC479 (n=5), CC20 (n=4), CC7 (n=1), CC9 (n=1), and CC45 (n=1). Although the latex-negative isolates were susceptible to all antimicrobial agents tested, 24% of latex-positive isolates were classified as intermediate with regard to cefalexin-kanamycin and 13% were resistant to both ampicillin and penicillin. Microarray profiles of latex-negative isolates were highly similar, but differed largely from those of latex-positive isolates. Although the latex-negative group lacked several enterotoxin genes and sak, it exhibited significantly

  5. Concrete radiation shielding

    SciTech Connect

    Kaplan, M.F.

    1989-01-01

    This book presents an introduction to the aspects of nuclear physics relevant to concrete technology. It covers a variety of materials that may be used to produce concrete for radiation shielding. Details of the physical, mechanical, and nuclear properties of these concretes are provided, and their applications in nuclear waste storage, shelter design, and reactor shielding are described. Radiation shield design considerations are addressed.

  6. Thinning of drying latex films due to surfactant.

    PubMed

    Gundabala, Venkata R; Routh, Alexander F

    2006-11-01

    Lateral non-uniformities in surfactant distribution in drying latex films induce surface tension gradients at the film surface and lead to film thinning through surfactant spreading. Here we investigate the influence of the surfactant driven to the air-water interface, during the early stages of latex film drying, on the film thinning process which could possibly lead to film rupture. A film height evolution equation is coupled with conservation equations for particles and surfactant, within the lubrication approximation, and solved numerically, to obtain the film height, particle volume fraction, and surfactant concentration profiles. Parametric analysis identifies the effect of drying rate, dispersion viscosity and initial particle volume fraction on film thinning and reveals the conditions under which films could rupture. The results from surface profilometry conform qualitatively to the model predictions.

  7. Process for preparation of large-particle-size monodisperse latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, D. M. (Inventor)

    1981-01-01

    Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarge particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment.

  8. High ionic strength electrokinetics of melamine-formaldehyde latex.

    PubMed

    Kosmulski, Marek; Dahlsten, Per; Próchniak, Piotr; Rosenholm, Jarl B

    2006-09-15

    The electrokinetic potential of melamine-formaldehyde latex at high ionic strengths was measured by means of two different instruments. The present study confirms that the zeta potentials in 1 M 1-1 electrolyte solutions can be as high as +/-20 mV. The IEP of latex at low ionic strengths was at pH 11. The increase in the electrolyte concentration induced a shift in the IEP to low pH for all studied salts, and this indicates specific adsorption of the anions. The magnitude of the shift depends chiefly on the nature of the anion and increases in the series Cl < NO(3) = Br < I, and the nature of the cation (Li, Na, K, Cs) plays a rather insignificant role.

  9. Antireflective structures via spin casting of polymer latex.

    PubMed

    Jiang, Hao; Yu, Ke; Wang, Yuechuan

    2007-03-01

    Introducing nanosized pores can greatly reduce the refractive index of thin films. Thus antireflective structures can be fabricated by controlled assembly of nanoparticles to form a nanoporous layer. We report what we believe to be the first example of preparing antireflective coatings on glass slides by spin casting polymer latex. Optical transmittances at 550 nm of 95.7% for a single-sided coating and 99.5% for a double-sided coating were achieved. Structure investigations with atomic force microscopy and scanning electron microscopy revealed that the antireflective coatings were highly porous and affected by spin speed and by the concentration and particle size of PMMA latex. Spin coating may be a better method for mass production, because of its convenience, low cost, and good reproducibility.

  10. Lunar concrete: Prospects and challenges

    NASA Astrophysics Data System (ADS)

    Khitab, Anwar; Anwar, Waqas; Mehmood, Imran; Kazmi, Syed Minhaj Saleem; Munir, Muhammad Junaid

    2016-02-01

    The possibility of using concrete as a construction material at the Moon surface is considered. Dissimilarities between the Earth and the Moon and their possible effects on concrete are also emphasized. Availability of constituent materials for concrete at lunar surface is addressed. An emphasis is given to two types of materials, namely, hydraulic concrete and sulfur concrete. Hydraulic concrete necessitates the use of water and sulfur concrete makes use of molten sulfur in lieu of cement and water.

  11. Cryo-sectioning and chemical-fixing ultramicrotomy techniques for imaging rubber latex particle morphology.

    PubMed

    Subramaniam, Nadaraja; Simpson, Anne; Monteiro, Michael J; Shaffer, Olga; Fellows, Christopher M; Gilbert, Robert G

    2004-02-01

    Two methods adapted from biological microscopy are described for a new application in imaging the morphology of rubbery latex particles. In the first method, a drop of latex is frozen in liquid nitrogen, sectioned with a diamond knife and vapour-stained with osmium tetroxide, then viewed by transmission electron microscopy. When applied to latexes made by emulsion polymerization of methyl methacrylate in a natural rubber latex seed, inclusions are clearly visible. A chemical fixation method is then described for imaging the morphology of such rubbery latex particles. Glutaraldehyde is added to the latex, followed by osmium tetroxide. The sample is then dehydrated in ethanol, epoxy resin added, and the sample cured, ultramicrotomed, and imaged with transmission electron microscopy. An inclusion morphology is again clearly seen. PMID:14722908

  12. Proteomic analysis of latex from the rubber-producing plant Taraxacum brevicorniculatum.

    PubMed

    Wahler, Daniela; Colby, Thomas; Kowalski, Natalie A; Harzen, Anne; Wotzka, Sandra Y; Hillebrand, Andrea; Fischer, Rainer; Helsper, Johannes; Schmidt, Jürgen; Schulze Gronover, Christian; Prüfer, Dirk

    2012-03-01

    Many plants produce latex, a specialized, metabolically active cytoplasm. This is generally regarded as a defensive trait but latex may also possess additional functions. We investigated the role of latex in the dandelion species Taraxacum brevicorniculatum that contains considerable amounts of high-quality natural rubber by carrying out a comprehensive analysis of the latex proteome. We developed reliable protocols for the preparation of protein samples for one-dimensional gel electrophoresis, two-dimensional gel electrophoresis, and subsequent mass spectrometry analysis, which led to 278 unique identifications. A gene ontology classification system based on comparisons with known Arabidopsis thaliana root proteins showed that dandelion proteins involved in lipid metabolism and transport were enriched in the latex proteome, whereas those involved in stress responses were not. We also found that proteins involved in rubber biosynthesis were distributed among different fractions of the latex proteome.

  13. Differentiating of cross-reactions in patients with latex allergy with the use of ISAC test

    PubMed Central

    Chełmińska, Marta; Różyło, Anna; Kołakowska, Agata; Jassem, Ewa

    2016-01-01

    Introduction Differentiating between cross-reactivity and double sensitization is still a challenging issue in allergology. Aim To differentiate cross-reactions accompanying latex allergy with the use of the ISAC test. Material and methods Thirty-nine patients reporting immediate allergic reactions to latex were enrolled into the study (group A). The control group was comprised of 41 patients with allergic diseases not associated with latex (group B) and 20 healthy individuals (group C). Their history was recorded and skin prick tests were performed with latex, airborne and food allergens. Specific IgE against food allergens, latex (k82) and recombined latex allergens were determined. ImmunoCAP ISAC test was performed with 103 molecules. Results Sensitization to latex was found by means of skin tests in 16 cases and sIgE against latex was revealed in 12 cases (including 10 positive in both SPT and sIgE). In the ISAC test antibodies against recombined latex allergens were found in 8 patients with rHev b 6 as the most common. All the patients positive for rHev b 1, 5, 6, 8 had allergy or asymptomatic sensitization to food allergens cross-reacting with latex. Some reactions could not have been differentiated due to the lack of allergens in the ISAC test. Others, not related to latex-fruits syndrome were explained by cross-reactivity with other profilins or PR-10 proteins. Conclusions ImmunoCAP ISAC test could be useful in differentiating between cross-reactions and double sensitizations. However, in the case of latex its advantages are limited due to a small panel of allergens. PMID:27279821

  14. Methods for ultimate load analysis of concrete containments

    SciTech Connect

    Dunham, R.S.; Rashid, Y.R.; Yuan, K.A.; Lu, Y.M.

    1985-06-01

    The objective of the research project described in this interim report is to develop a qualified methodology for the ultimate load analysis of concrete containment structures. The EPRI-sponsored nonlinear finite element code ABAQUS-EPGEN, which has recently been modified to incorporate a constitutive model for plain concrete and modeling capabilities for reinforced and prestressed concrete containments, is utilized as the structural analysis tool in this development. The ABAQUS-EPGEN concrete modeling and analysis capabilities are first evaluated by comparing measured data with code predictions for full-scale reinforced concrete slab specimens tested under uniaxial and biaxial tension. These specimen tests simulate the behavior of the cylindrical wall of a typical concrete containment structure under internal pressure. The calculated and measured strain comparisons are used to improve the constitutive model and to qualify the code for concrete containment analysis. The second part of this effort deals with the ultimate load analysis of reinforced and prestressed containments to determine bounds on the global overpressure capacities of typical concrete containment structures. The third part of this effort further examines such local effects through a substructural analysis of the liner-concrete interaction at major concrete cracks.

  15. Evaluation of cytotoxicity and genotoxicity of Hancornia speciosa latex in Allium cepa root model.

    PubMed

    Ribeiro, T P; Sousa, T R; Arruda, A S; Peixoto, N; Gonçalves, P J; Almeida, L M

    2016-02-01

    The latex obtained from Hancornia speciosa Gomes (Mangabeira tree) is widely used in traditional medicine to treat a variety of diseases, including diarrhea, ulcer, gastritis, tuberculosis, acne and warts. In this study, the cytotoxicity and genotoxicity effects of H. speciosa latex on the root meristem cells of Allium cepa were examined. Onion bulbs were exposed to different concentrations of latex and then submitted to microscopic analysis using Giemsa stain. Water was used as a negative control and sodium azide as a positive control. The results showed that, under the testing conditions, the mitotic index (MI) of the onion roots submitted to latex treatment did not differ significantly from the negative control, which suggests that the latex is not cytotoxic. Low incidence of chromosome aberrations in the cells treated with H. speciosa latex was also observed, indicating that the latex does not have genotoxic effect either. The MI and the chromosome aberration frequency responded to the latex concentration, requiring more studies to evaluate the dosage effect on genotoxicity. The results indicate that in tested concentrations H. speciosa latex is probably not harmful to human health and may be potentially used in medicine. PMID:26909640

  16. Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production.

    PubMed

    Wang, Xuchu; Wang, Dan; Sun, Yong; Yang, Qian; Chang, Lili; Wang, Limin; Meng, Xueru; Huang, Qixing; Jin, Xiang; Tong, Zheng

    2015-09-08

    Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production.

  17. Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production

    PubMed Central

    Wang, Xuchu; Wang, Dan; Sun, Yong; Yang, Qian; Chang, Lili; Wang, Limin; Meng, Xueru; Huang, Qixing; Jin, Xiang; Tong, Zheng

    2015-01-01

    Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production. PMID:26348427

  18. Effects of the Papaya meleira virus on papaya latex structure and composition.

    PubMed

    Rodrigues, Silas P; Da Cunha, Maura; Ventura, José A; Fernandes, Patricia Machado Bueno

    2009-05-01

    Spontaneous latex exudation is the main symptom of papaya sticky (meleira) disease caused by the Papaya meleira virus (PMeV), a double-stranded RNA (dsRNA) virus. This paper describes different effects of PMeV on papaya latex. Latex samples were subjected to different histochemical tests to evaluate their chemical composition. Additionally, the integrity of the latex particles was assessed by transmission and scanning electron microscopy analysis. Biochemical and micro- and macro-element measurements were performed. PMeV dsRNA extraction was performed to evaluate the interaction of the virus with the latex particles. Sticky diseased latex was positive for alkaloid biosynthesis and showed an accumulation of calcium oxalate crystals. PMeV also increased H(2)O(2) synthesis within sticky diseased laticifers. The protein, sugar and water levels were altered, probably due to chemical changes. The morphology of the latex particles was further altered; PMeV particles seemed to be bound to the latex particles. The alkaloid and H(2)O(2) biosynthesis in the papaya laticifers indicate a papaya defense response against PMeV. However, such efforts failed, as the virus affected the plant latex. The effects described here suggest some advantages of the infection process, including facilitating the movement of the virus within the papaya plant.

  19. Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production.

    PubMed

    Wang, Xuchu; Wang, Dan; Sun, Yong; Yang, Qian; Chang, Lili; Wang, Limin; Meng, Xueru; Huang, Qixing; Jin, Xiang; Tong, Zheng

    2015-01-01

    Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production. PMID:26348427

  20. Correlating particle deformation with water concentration profiles during latex film formation: reasons that softer latex films take longer to dry.

    PubMed

    Carter, Farai T; Kowalczyk, Radoslaw M; Millichamp, Ian; Chainey, Malcolm; Keddie, Joseph L

    2014-08-19

    During the past two decades, an improved understanding of the operative particle deformation mechanisms during latex film formation has been gained. For a particular colloidal dispersion, the Routh-Russel deformation maps predict the dominant mechanism for particle deformation under a particular set of conditions (evaporation rate, temperature, and initial film thickness). Although qualitative tests of the Routh-Russel model have been reported previously, a systematic study of the relationship between the film-formation conditions and the resulting water concentration profiles is lacking. Here, the water distributions during the film formation of a series of acrylic copolymer latexes with varying glass-transition temperatures, Tg (values of -22, -11, 4, and 19 °C), have been obtained using GARField nuclear magnetic resonance profiling. A significant reduction in the rate of water loss from the latex copolymer with the lowest Tg was found, which is explained by its relatively low polymer viscosity enabling the growth of a coalesced skin layer. The set of processing parameters where the drying first becomes impeded occurs at the boundary between the capillary deformation and the wet sintering regimes of the Routh-Russel model, which provides strong confirmation of the model's validity. An inverse correlation between the model's dimensionless control parameter and the dimensionless drying time is discovered, which is useful for the design of fast-drying waterborne films.

  1. Antifouling marine concrete

    NASA Astrophysics Data System (ADS)

    Mathews, C. W.

    1980-03-01

    Various toxic agents were investigated for their ability to prevent the attachment and growth of marine fouling organisms on concrete. Three methods of incorporating antifoulants into concrete were also studied. Porous aggregate was impregnated with creosote and bis-(tri-n-butyltin) oxide (TBTO) and then used in making the concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, Calif. and Key Biscayne, Fla. Efficacy of toxicants was determined by periodically weighing the specimens and the fouling organisms that became attached. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture demonstrated the best antifouling performance of those specimens exposed for more than 1 year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties but have been exposed for a shorter time. Also, the strength of concrete prepared using the toxicants was acceptable and the corrosion rate of reinforcing rods did not increase. The concentration of organotin compounds was essentially unchanged in a concrete specimen exposed 6-1/2 years in seawater.

  2. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack.

    PubMed

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A M; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground. PMID:26731567

  3. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack.

    PubMed

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A M; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground.

  4. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack

    PubMed Central

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G.; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A. M.; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground. PMID:26731567

  5. Efficacy and phytochemical analysis of latex of Calotropis procera against selected dermatophytes

    PubMed Central

    Aliyu, Rabiu Muhammad; Abubakar, Mikaeel Bala; Kasarawa, Adamu Bello; Dabai, Yakubu Umar; Lawal, Nafiu; Bello, Muhammad Bashir; Fardami, Aminu Yusuf

    2015-01-01

    Background: Since ancient time, increased interest has been witnessed in the use of an alternative herbal medicine for managing, and the treatment of fungal diseases worldwide. This may be connected to the cost and relative toxicities of the available antifungal drugs. It has been a known tradition practiced in the northern part of Nigeria that parents and teachers use the white latex of Calotropis procera to treat Tinea capitis in children attending the local religious school in the area. This study was conducted in 2009 to ascertain the above claim. Materials and Methods: Fresh latex of C. procera was screened for their antifungal activity against species of dermatophytes: Trichophyton spp., Microsporum spp. and Epidermophyton spp. using the agar incorporation method. Results: The result shows that the latex inhibits the in vitro growth of these pathogenic fungi to varying extents with Trichophyton spp. being the most susceptible (P < 0.05) and thus highly inhibited by the latex followed by the Microsporum spp. and Epidermopyton spp. was least inhibited. These inhibitions followed a dose-dependent trend as undiluted latex (100%) gave the highest inhibitory impacts (P < 0.05) when compared to serially diluted latex. The phytochemical analysis of the fresh latex indicated the presence of alkaloids, saponin, tannins, steroids, flavonoids, anthraquinone, and triterpenoids. Conclusion: The findings of this study confirmed the perceived usefulness of the latex in the treatment of T. capitis (ringworm) practiced in our society and therefore, its use topically in the treatment of dermatomycotic infection is encouraged. PMID:26649237

  6. Cysteine proteases from the Asclepiadaceae plants latex exhibited thrombin and plasmin like activities.

    PubMed

    Shivaprasad, H V; Riyaz, M; Venkatesh Kumar, R; Dharmappa, K K; Tarannum, Shaista; Siddesha, J M; Rajesh, R; Vishwanath, B S

    2009-10-01

    In the present study we evaluated the presence of cysteine protease from the latex of four plants Asclepias curassavica L., Calotropis gigantea R.Br., Pergularia extensa R.Br. and Cynanchum puciflorum R.Br. belongs to the family Asclepiadaceae. Cysteine proteases from these plants latex exhibited both thrombin and plasmin like activities. Latex enzyme fraction in a concentration dependent manner induced the formation of clot in citrated blood plasma. Direct incubation of fibrinogen with latex enzyme fraction resulted in the formation of fibrin clot similar to thrombin enzyme. However prolonged incubation resulted in degradation of the formed fibrin clot suggesting plasmin like activity. Latex enzyme fraction preferentially hydrolyzed Aalpha and Bbeta chains of fibrinogen to form fibrin clot. Latex enzyme fraction also hydrolyzed the subunits of fully cross linked fibrin efficiently, the order of hydrolysis was alpha-polymer > alpha-chains > beta-chain and gamma-gamma dimer. Cysteine proteases from all the four Asclepiadaceae plants latex exhibited similar action on fibrinogen and fibrin. This study scientifically validate the use of plant latex in stop bleeding and wound healing by traditional healers all over the world.

  7. Synthesis and characterization of core-shell acrylate based latex and study of its reactive blends.

    PubMed

    Liu, Xiang; Fan, Xiao-Dong; Tang, Min-Feng; Nie, Ying

    2008-03-01

    Techniques in resin blending are simple and efficient method for improving the properties of polymers, and have been used widely in polymer modification field. However, polymer latex blends such as the combination of latexes, especially the latexes with water-soluble polymers, were rarely reported. Here, we report a core-shell composite latex synthesized using methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) and glycidyl methacrylate (GMA) as monomers and ammonium persulfate and sodium bisulfite redox system as the initiator. Two stages seeded semi-continuous emulsion polymerization were employed for constructing a core-shell structure with P(MMA-co-BA) component as the core and P(EHA-co-GMA) component as the shell. Results of Transmission Electron Microscopy (TEM) and Dynamics Light Scattering (DLS) tests confirmed that the particles obtained are indeed possessing a desired core-shell structural character. Stable reactive latex blends were prepared by adding the latex with waterborne melamine-formaldehyde resin (MF) or urea-formaldehyde resin (UF). It was found that the glass transition temperature, the mechanical strength and the hygroscopic property of films cast from the latex blends present marked enhancements under higher thermal treatment temperature. It was revealed that the physical properties of chemically reactive latexes with core-shell structure could be altered via the change of crosslinking density both from the addition of crosslinkers and the thermal treatment.

  8. Involvement of Ethylene in the Latex Metabolism and Tapping Panel Dryness of Hevea brasiliensis

    PubMed Central

    Putranto, Riza-Arief; Herlinawati, Eva; Rio, Maryannick; Leclercq, Julie; Piyatrakul, Piyanuch; Gohet, Eric; Sanier, Christine; Oktavia, Fetrina; Pirrello, Julien; Kuswanhadi; Montoro, Pascal

    2015-01-01

    Ethephon, an ethylene releaser, is used to stimulate latex production in Hevea brasiliensis. Ethylene induces many functions in latex cells including the production of reactive oxygen species (ROS). The accumulation of ROS is responsible for the coagulation of rubber particles in latex cells, resulting in the partial or complete stoppage of latex flow. This study set out to assess biochemical and histological changes as well as changes in gene expression in latex and phloem tissues from trees grown under various harvesting systems. The Tapping Panel Dryness (TPD) susceptibility of Hevea clones was found to be related to some biochemical parameters, such as low sucrose and high inorganic phosphorus contents. A high tapping frequency and ethephon stimulation induced early TPD occurrence in a high latex metabolism clone and late occurrence in a low latex metabolism clone. TPD-affected trees had smaller number of laticifer vessels compared to healthy trees, suggesting a modification of cambial activity. The differential transcript abundance was observed for twenty-seven candidate genes related to TPD occurrence in latex and phloem tissues for ROS-scavenging, ethylene biosynthesis and signalling genes. The predicted function for some Ethylene Response Factor genes suggested that these candidate genes should play an important role in regulating susceptibility to TPD. PMID:26247941

  9. Synthesis and Characterization of Core-Shell Acrylate Based Latex and Study of Its Reactive Blends

    PubMed Central

    Liu, Xiang; Fan, Xiao-Dong; Tang, Min-Feng; Nie, Ying

    2008-01-01

    Techniques in resin blending are simple and efficient method for improving the properties of polymers, and have been used widely in polymer modification field. However, polymer latex blends such as the combination of latexes, especially the latexes with water-soluble polymers, were rarely reported. Here, we report a core-shell composite latex synthesized using methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) and glycidyl methacrylate (GMA) as monomers and ammonium persulfate and sodium bisulfite redox system as the initiator. Two stages seeded semi-continuous emulsion polymerization were employed for constructing a core-shell structure with P(MMA-co-BA) component as the core and P(EHA-co-GMA) component as the shell. Results of Transmission Electron Microscopy (TEM) and Dynamics Light Scattering (DLS) tests confirmed that the particles obtained are indeed possessing a desired core-shell structural character. Stable reactive latex blends were prepared by adding the latex with waterborne melamine-formaldehyde resin (MF) or urea-formaldehyde resin (UF). It was found that the glass transition temperature, the mechanical strength and the hygroscopic property of films cast from the latex blends present marked enhancements under higher thermal treatment temperature. It was revealed that the physical properties of chemically reactive latexes with core-shell structure could be altered via the change of crosslinking density both from the addition of crosslinkers and the thermal treatment. PMID:19325753

  10. Permeability of latex and polyvinyl chloride gloves to 20 antineoplastic drugs.

    PubMed

    Laidlaw, J L; Connor, T H; Theiss, J C; Anderson, R W; Matney, T S

    1984-12-01

    Permeability of latex and polyvinyl chloride (PVC) gloves to 20 injectable antineoplastic drugs was studied. Four types of gloves were evaluated: latex surgical gloves, latex examination gloves, and PVC gloves in two thicknesses. Each glove material was exposed to each drug for 90 minutes, and permeation was tested using a mutagenicity assay. Individual fingertips of thin PVC gloves and latex surgical gloves were tested for permeability at five time points (2-30 minutes) using a doxorubicin coloration assay. All drugs permeated the thin PVC gloves. Latex surgical gloves were definitely permeable to two drugs (carmustine and thiotepa) and exhibited borderline permeability to mechlorethamine hydrochloride. The thick PVC gloves were definitely permeable to four drugs (carmustine, thiotepa, mechlorethamine hydrochloride, and daunorubicin hydrochloride) and exhibited borderline permeability to two drugs (doxorubicin and mercaptopurine). The latex examination gloves were permeable to carmustine, thiotepa, mechlorethamine hydrochloride, and cyclophosphamide. Doxorubicin permeation of individual fingertips of thin PVC gloves varied in time and amount. Doxorubicin did not permeate the latex surgical glove material, but testing with thiotepa showed that individual fingertips of this material also varied in permeability. Glove thickness was a major determinant of permeability; latex surgical gloves were the least permeable and thin PVC gloves the most permeable to the antineoplastic drugs tested. Within individual gloves and glove types, time and amount of permeation were not uniform. PMID:6440436

  11. Polymer composites prepared from heat-treated starch and styrene-butadiene latex

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoplastic starch/latex polymer composites were prepared using styrene–butadiene (SB) latex and heat-treated cornstarch. The composites were prepared in a compression mold at 130 °C, with starch content 20%. An amylose-free cornstarch, waxy maize, was used for this research and the heat treatment...

  12. Dual latex/surfactant templating of hollow spherical silica particles with ordered mesoporous shells.

    PubMed

    Tan, Bing; Rankin, Stephen E

    2005-08-30

    Hollow spherical silica particles with hexagonally ordered mesoporous shells are synthesized with the dual use of cetyltrimethylammonium bromide (CTAB) and unmodified polystyrene latex microspheres as templates in concentrated aqueous ammonia. In most of the hollow mesoporous particles, cylindrical pores run parallel to the hollow core due to interactions of CTAB/silica aggregates with the latices. Effects on the product structure of the CTAB:latex ratio, the amount of aqueous ammonia, and the latex size are studied. Hollow particles with hexagonally patterned mesoporous shells are obtained at moderate CTAB:latex ratios. Too little CTAB causes silica shell growth without surfactant templating, and too much induces nucleation of new mesoporous silica particles without latex cores. The concentration of ammonia must be large to induce co-assembly of CTAB, silica, and latex into dispersed particles. The results are consistent with the formation of particles by addition of CTAB/silica aggregates to the surface of latex microspheres. When the size and number density of the latex microspheres are changed, the size of the hollow core and the shell thickness can be controlled. However, if the microspheres are too small (50 nm in this case), agglomerated particles with many hollow voids are obtained, most likely due to colloidal instability.

  13. Involvement of Ethylene in the Latex Metabolism and Tapping Panel Dryness of Hevea brasiliensis.

    PubMed

    Putranto, Riza-Arief; Herlinawati, Eva; Rio, Maryannick; Leclercq, Julie; Piyatrakul, Piyanuch; Gohet, Eric; Sanier, Christine; Oktavia, Fetrina; Pirrello, Julien; Kuswanhadi; Montoro, Pascal

    2015-08-04

    Ethephon, an ethylene releaser, is used to stimulate latex production in Hevea brasiliensis. Ethylene induces many functions in latex cells including the production of reactive oxygen species (ROS). The accumulation of ROS is responsible for the coagulation of rubber particles in latex cells, resulting in the partial or complete stoppage of latex flow. This study set out to assess biochemical and histological changes as well as changes in gene expression in latex and phloem tissues from trees grown under various harvesting systems. The Tapping Panel Dryness (TPD) susceptibility of Hevea clones was found to be related to some biochemical parameters, such as low sucrose and high inorganic phosphorus contents. A high tapping frequency and ethephon stimulation induced early TPD occurrence in a high latex metabolism clone and late occurrence in a low latex metabolism clone. TPD-affected trees had smaller number of laticifer vessels compared to healthy trees, suggesting a modification of cambial activity. The differential transcript abundance was observed for twenty-seven candidate genes related to TPD occurrence in latex and phloem tissues for ROS-scavenging, ethylene biosynthesis and signalling genes. The predicted function for some Ethylene Response Factor genes suggested that these candidate genes should play an important role in regulating susceptibility to TPD.

  14. Structure and properties of composite films formed by cellulose nanocrystals and charged latex nanoparticles.

    PubMed

    Thérien-Aubin, Héloïse; Lukach, Ariella; Pitch, Natalie; Kumacheva, Eugenia

    2015-04-21

    We report the structural and optical properties of composite films formed from mixed suspensions of cellulose nanocrystals (CNCs) and fluorescent latex nanoparticles (NPs). We explored the effect of NP concentration, size, surface charge, glass transition temperature and film processing conditions on film structure and properties. The chiral nematic order, typical of CNC films, was preserved in films with up to 50 wt% of negatively-charged latex NPs. Composite films were characterized by macroscopically close-to-uniform fluorescence, birefringence, and circular dichroism properties. In contrast, addition of positively charged latex NPs led to gelation of CNC-latex suspensions and disruption of the chiral nematic order in the composite films. Large latex NPs disrupted the chiral nematic order to a larger extend than small NPs. Furthermore, the glass transition of latex NPs had a dramatic effect on the structure of CNC-latex films. Latex particles in the rubbery state were easily incorporated in the ordered CNC matrix and improved the structural integrity of its chiral nematic phase. PMID:25792388

  15. Hancornia speciosa latex for biomedical applications: physical and chemical properties, biocompatibility assessment and angiogenic activity.

    PubMed

    Almeida, Luciane Madureira; Floriano, Juliana Ferreira; Ribeiro, Thuanne Pires; Magno, Lais Nogueira; da Mota, Lígia Souza Lima Silveira; Peixoto, Nei; Mrué, Fátima; Melo-Reis, Paulo; Lino Junior, Ruy de Souza; Graeff, Carlos Frederico de Oliveira; Gonçalves, Pablo José

    2014-09-01

    The latex obtained from Hancornia speciosa is used in folk medicine for treatment of several diseases, such as acne, warts, diabetes, gastritis and inflammation. In this work, we describe the biocompatibility assessment and angiogenic properties of H. speciosa latex and its potential application in medicine. The physical-chemical characterization was carried out following different methodologies (CHN elemental analyses; thermogravimetric analyses and Fourier transform infrared spectroscopy). The biocompatibility was evaluated through cytotoxicity and genotoxicity tests in fibroblast mouse cells and the angiogenic properties were evaluated using the chick chorioallantoic membrane (CAM) assay model. The physical-chemical results showed that the structure of Hancornia speciosa latex biomembrane is very similar to that of Hevea brasiliensis (commercially available product). Moreover, the cytotoxicity and genotoxicity assays showed that H. speciosa latex is biocompatible with life systems and can be a good biomaterial for medical applications. The CAM test showed the efficient ability of H. speciosa latex in neovascularization of tissues. The histological analysis was in accordance with the results obtained in the CAM assay. Our data indicate that the latex obtained from H. speciosa and eluted in water showed significant angiogenic activity without any cytotoxic or genotoxic effects on life systems. The same did not occur with H. speciosa latex stabilized with ammonia. Addition of ammonia does not have significant effects on the structure of biomembranes, but showed a smaller cell survival and a significant genotoxicity effect. This study contributes to the understanding of the potentialities of H. speciosa latex as a source of new phytomedicines.

  16. Permeability of latex and polyvinyl chloride gloves to 20 antineoplastic drugs.

    PubMed

    Laidlaw, J L; Connor, T H; Theiss, J C; Anderson, R W; Matney, T S

    1984-12-01

    Permeability of latex and polyvinyl chloride (PVC) gloves to 20 injectable antineoplastic drugs was studied. Four types of gloves were evaluated: latex surgical gloves, latex examination gloves, and PVC gloves in two thicknesses. Each glove material was exposed to each drug for 90 minutes, and permeation was tested using a mutagenicity assay. Individual fingertips of thin PVC gloves and latex surgical gloves were tested for permeability at five time points (2-30 minutes) using a doxorubicin coloration assay. All drugs permeated the thin PVC gloves. Latex surgical gloves were definitely permeable to two drugs (carmustine and thiotepa) and exhibited borderline permeability to mechlorethamine hydrochloride. The thick PVC gloves were definitely permeable to four drugs (carmustine, thiotepa, mechlorethamine hydrochloride, and daunorubicin hydrochloride) and exhibited borderline permeability to two drugs (doxorubicin and mercaptopurine). The latex examination gloves were permeable to carmustine, thiotepa, mechlorethamine hydrochloride, and cyclophosphamide. Doxorubicin permeation of individual fingertips of thin PVC gloves varied in time and amount. Doxorubicin did not permeate the latex surgical glove material, but testing with thiotepa showed that individual fingertips of this material also varied in permeability. Glove thickness was a major determinant of permeability; latex surgical gloves were the least permeable and thin PVC gloves the most permeable to the antineoplastic drugs tested. Within individual gloves and glove types, time and amount of permeation were not uniform.

  17. VOLATILE ORGANIC COMPOUND EMISSIONS FROM LATEX PAINT - PART 1. CHAMBER EXPERIMENTS AND SOURCE MODEL DEVELOPMENT

    EPA Science Inventory

    Latex paints are widely used in residential and commercial indoor environments. The surface areas covered by the paints in these environments are relatively large. Thus, latex paints have the potential for having a major impact on indoor air quality (IAQ). A study was undertaken ...

  18. Development and evaluation of a latex agglutination test for the rapid serodiagnosis of tularemia.

    PubMed

    Rastawicki, Waldemar; Rokosz-Chudziak, Natalia; Chróst, Anna; Gierczyński, Rafał

    2015-05-01

    A latex agglutination test (LAT) was developed for a rapid detection of antibodies against Francisella tularensis. The assay is performed by mixing serum with antigen-coated latex beads and read within 5 min. Developed LAT has been proved to be a specific, sensitive, fast, easy-to-perform and cost-efficient tool for the routine diagnosis of tularemia.

  19. Cytotoxic Orbitide from the Latex of Croton urucurana.

    PubMed

    Cândido-Bacani, Priscila de M; Figueiredo, Patrícia de O; Matos, Maria de F C; Garcez, Fernanda R; Garcez, Walmir S

    2015-11-25

    The bioactive ethyl acetate phase obtained from the latex of Croton urucurana Baillon afforded a novel orbitide (1), [1-9-NαC]-crourorb A1, that proved active against NCI-ADR/RES (ovary, multidrug-resistance phenotype) cells with the same potency as doxorubicin (positive control) and inactive up to the highest concentration tested against nontumor NIH/3T3 cells. The structure elucidation was based on 1D and 2D NMR spectroscopy, further supported by HRESIMS data and by application of Marfey's method for determination of the absolute configuration of its amino acid residues. This is the first orbitide obtained from C. urucurana.

  20. Cytotoxic Orbitide from the Latex of Croton urucurana.

    PubMed

    Cândido-Bacani, Priscila de M; Figueiredo, Patrícia de O; Matos, Maria de F C; Garcez, Fernanda R; Garcez, Walmir S

    2015-11-25

    The bioactive ethyl acetate phase obtained from the latex of Croton urucurana Baillon afforded a novel orbitide (1), [1-9-NαC]-crourorb A1, that proved active against NCI-ADR/RES (ovary, multidrug-resistance phenotype) cells with the same potency as doxorubicin (positive control) and inactive up to the highest concentration tested against nontumor NIH/3T3 cells. The structure elucidation was based on 1D and 2D NMR spectroscopy, further supported by HRESIMS data and by application of Marfey's method for determination of the absolute configuration of its amino acid residues. This is the first orbitide obtained from C. urucurana. PMID:26561866

  1. Mobility and surfactant migration in EA/MAA latex films; ATR FT-IR spectroscopic study

    SciTech Connect

    Thorstenson, T.A.; Tebelius, L.K.; Urban, M.W.

    1993-12-31

    Although numerous factors such as compatibility, mechanical deformation, and the nature of the substrate have been addressed with respect to surfactant migration and distribution within latex films, latex suspension stability and the effects of particle flocculation are also key issues. In this paper, surfactant behavior in an ethyl acrylate/methacrylic acid/sodium dioctyl sulfosuccinate (EA/MAA/SDOSS) latex system is monitored as a function of stability of the liquid latex suspensions. Particle size data obtained using light scattering reveals an appreciable degree of flocculation over the period of study. It is found that flocculation is paralleled by a significantly increased degree of interfacial surfactant enrichment, a monitored by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR). It is concluded that the enhanced surfactant exudation observed for flocculated latexes is due to displacement of adsorbed surfactant during the course of flocculation.

  2. Biaxial flex-fatigue and viral penetration of natural rubber latex gloves before and after artificial aging.

    PubMed

    Schwerin, Matthew R; Walsh, Donna L; Coleman Richardson, D; Kisielewski, Richard W; Kotz, Richard M; Routson, Licia B; David Lytle, C

    2002-01-01

    Barrier integrity of unaged and oven-aged (at 70 degrees C) natural rubber latex examination gloves was assessed with a biaxial flex-fatigue method where failure was detected electronically, and by live viral penetration testing performed according to a modified version of ASTM F1671-97a. When no change in barrier properties was detected during flex testing, no virus passage was found after viral challenge. Conversely, when a change in the barrier properties was indicated by the electrical signal, virus passage was found in 74% of the specimens. Flex-fatigue results indicated that unaged test specimens from powdered (PD) and powder-free (PF) nonchlorinated gloves had significantly longer fatigue lives than powder-free chlorinated (CL) gloves from the same manufacturer. Biaxial flexing of oven-aged glove specimens showed a marginal increase in fatigue life for the PF gloves, but no increase for the PD gloves. The fatigue life of the CL gloves was observed to increase significantly after oven aging. However, this appears to be due to a design feature of the test apparatus, wherein peak volume displacement of the worked specimen is held constant. An aging-induced change in the viscoelastic properties of the CL gloves-permanent deformation of the specimens early in the fatigue test-relieves the stress magnitude applied as the test progresses. Thus, permanent deformation acts as a confounding factor in measuring durability of latex gloves by fixed displacement flex-fatigue.

  3. Concrete sample point: 304 Concretion Facility

    SciTech Connect

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  4. Electrokinetic decontamination of concrete

    SciTech Connect

    Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.

    1996-12-31

    ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers` health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE`s Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building`s concrete floors included ThO{sub 2} and thorium oxalate. The nitric acid was found to facilitate Th extraction.

  5. Performance of Waterless Concrete

    NASA Technical Reports Server (NTRS)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  6. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as the their capability to prevent or inhibit the attachment of marine fouling organisms to concrete. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6 1/2 years in seawater.

  7. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as to their capability to prevent or inhibit the attachment of marine fouling organisms to concrete for OTEC plants. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6-1/2 years in seawater.

  8. Scattering of coherent and incoherent light by latex hydrosols.

    PubMed

    Sherman, G C; Harris, F S; Morse, F L

    1968-03-01

    Experimental study of the scattering of coherent and incoherent light by latex hydrosols has been extended to determine the effects of larger diameter scatterers and of several scatterer concentrations. The angular dependence of the intensity of the light scattered by latex spheres suspended in water was measured. Two light sources were used: (1) a continuous wave He-Ne laser radiating at 6328 A and (2) a high pressure, xenon arc lamp limited to a 100-micro bandwidth centered at 6328 A. The number of particles in the scattering volume coherently illuminated with the laser was greater than the number coherently illuminated with the xenon lamp by a factor > 5 x 10(5). Six hydrosols were studied: three suspensions of particles polydispersed in size (diameter ranges from 6 micro to 14 micro, 12 micro to 35 micro, and 25 micro to 55 micro) and three suspensions of particles monodispersed in size (0.796-micro diam and concentration ranging from 5.7 x 10(7) particles/cm(3) to 5.7 x 10(5) particles/cm(3)). For these six suspensions, the data from the two light sources agree to within the possible experimental error of 20%.

  9. Identification of a new phospholipase D in Carica papaya latex.

    PubMed

    Abdelkafi, Slim; Abousalham, Abdelkarim; Fendri, Imen; Ogata, Hiroyuki; Barouh, Nathalie; Fouquet, Benjamin; Scheirlinckx, Frantz; Villeneuve, Pierre; Carrière, Frédéric

    2012-05-15

    Phospholipase D (PLD) is a lipolytic enzyme involved in signal transduction, vesicle trafficking and membrane metabolism. It catalyzes the hydrolysis and transphosphatidylation of glycerophospholipids at the terminal phosphodiester bond. The presence of a PLD in the latex of Carica papaya (CpPLD1) was demonstrated by transphosphatidylation of phosphatidylcholine (PtdCho) in the presence of 2% ethanol. Although the protein could not be purified to homogeneity due to its presence in high molecular mass aggregates, a protein band was separated by SDS-PAGE after SDS/chloroform-methanol/TCA-acetone extraction of the latex insoluble fraction. This material was digested with trypsin and the amino acid sequences of the tryptic peptides were determined by micro-LC/ESI/MS/MS. These sequences were used to identify a partial cDNA (723 bp) from expressed sequence tags (ESTs) of C. papaya. Based upon EST sequences, a full-length gene was identified in the genome of C. papaya, with an open reading frame of 2424 bp encoding a protein of 808 amino acid residues, with a theoretical molecular mass of 92.05 kDa. From sequence analysis, CpPLD1 was identified as a PLD belonging to the plant phosphatidylcholine phosphatidohydrolase family.

  10. Hydroxyapatite moldable formulation using natural rubber latex as binder.

    PubMed

    Sailaja, G S; Ramesh, P; Varma, H K

    2007-07-01

    A simple but efficient processing method for shaping intricate bioceramic green bodies has been developed by using natural rubber latex as binder. Different shapes of hydroxyapatite Ca10(PO4)6(OH)2 (HAP) were molded from a composite formulation containing wet precipitated HAP, natural rubber latex (NRL), and a stabilizer. On controlled heat treatment followed by sintering, dense shapes of HAP contours were obtained. The thermal degradation profile of HAP-NRL composites shows that NRL degrades slowly without any abrupt exotherm. The results of energy dispersive X-ray analysis together with inductively coupled plasma (ICP) analysis indicate that the inorganic residue of NRL does not contain any heavy element. The sintered density of the samples increased with increased HAP content in the formulation and percentage shrinkage reduced accordingly. On varying the HAP content in the formulation from 35 to 95 wt %, the compositions with 85, 90, 92, and 95 wt % HAP showed better flexural strength in the range 40-54 MPa and a flexural modulus value in the range 36-50 GPa. The fracture morphology, as observed by the scanning electron microscope confirms that with increased HAP content in the formulation the sample microstructure attains higher uniformity. The Vickers microhardness for the samples sintered at two different temperatures (1150 and 1250 degrees C) showed that hardness increases with increase in the sintering temperature with a maximum for the highest HAP loaded formulation.

  11. Contact Allergic Cheilitis Secondary to Latex Gloves: a Case Report

    PubMed Central

    Rangare, Anusha; Babu, Subhas; Rao, Prasanna

    2011-01-01

    ABSTRACT Background The purpose of this report is to present a rare case of allergic chelitis secondary to latex in an elderly diabetic patient. There are very few reported cases of allergic cheilitis in literature. Most of the reported cases of allergic chelitis were secondary to cosmetics, tooth pastes or impression materials. Few cases of rubber dam induced allergic cheilitis and stomatitis reported. Methods Since the patient was diabetic on insulin therapy and belonged to the elderly age group, utmost caution was observed while performing diagnostic tests and treatment procedures. The use test was performed to detect the allergen (latex) because of short contact time to the skin surface. Results The patient was followed-up for a period of eight months, complete healing of the lesions was witnessed. The patient has not reported of any lesions later. Conclusions Appropriate diagnostic test and interdisciplinary approach in consultation with medical specialists would be ideal for the management of allergic cheilitis especially in diabetic elderly patients. PMID:24421987

  12. Biodecontamination of concrete

    SciTech Connect

    Hamilton, M.A.; Rogers, R.D.; Benson, J.

    1996-12-31

    A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology.

  13. Electrokenitic Corrosion Treatment of Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E (Inventor)

    2015-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  14. Latex allergy in healthcare workers: an epidemiological study in a Spanish hospital.

    PubMed

    Diéguez, Maria Carmen; Pulido, Zeida; de la Hoz, Belén; Blanco, Rosa; Cerecedo, Inmaculada; Fernández-Caldas, Enrique; Swanson, Michel

    2007-01-01

    To design an effective prevention program in health care workers who are allergic to latex it is necessary to know the current epidemiological situation. The objectives were to determine the main factors associated with latex allergy and to quantify levels of airborne latex particles in different areas of our hospital. A cross-sectional study was conducted using a questionnaire completed by health care workers. Those who answered the first questionnaire were given a second one to fill out and an allergological study (skin-prick test and latex-specific IgE antibodies) was performed. Latex aeroallergen particles were collected with a Quan-tec-air in different areas of the hospital. The first questionnaire was sent to 2551 health care workers. Eight hundred forty-one (33.14%) subjects returned the completed questionnaire and were given the second questionnaire. One hundred fifty-four completed second questionnaire. We identified 28 patients who were allergic to latex, and 126 patients who were not allergic to latex. In the allergic population there were more nurses aides. More allergic patients were found in the Surgery Department, Intensive Care Unit (ICU), and Vascular Radiology Unit (VRU). Allergic patients were more likely to use a higher number of latex gloves and during more hours than nonallergic workers. In the Surgery Department, ICU, VRU, and Laboratory Department more pairs of latex gloves were used and during more hours. The medium level of latex aeroallergens in 24 determinations in 14 areas of the hospital was 8.12 ng/m3 (SD, 13.32 ng/m3; range, 0.3-57.7 ng/m3). The higher levels were found in Laboratory (n = 2; mean (M) 23; SD, 25.95 ng/m3) and Surgery Departments (n = 11; M, 7.43; SD, 16.98 ng/m3; Kruskal Wallis test, p = 0.09). Latex allergy is an important health problem for health care workers, especially for those working in surgical areas or in those places where more latex gloves are used; in these areas higher levels of airborne latex particles

  15. Precast concrete pavements

    NASA Astrophysics Data System (ADS)

    Rollings, R. S.; Chou, Y. T.

    1981-11-01

    This report reviewed published literature on precast concrete pavements and found that precast concrete pavements have had some limited application in airfields, roads, and storage areas. This review of past experience and an analytical study of precast slabs concluded that existing design and construction techniques can be adapted for use with precast concrete pavements, but more work is needed to develop effective and easily constructed load transfer designs for slab joints. Precast concrete does not offer any advantage for conventional pavements due to its high cost and surface roughness, but it may find applications for special problems such as construction in adverse weather, subgrade settlement, temporary pavements that need to be relocated, and military operations.

  16. Strengthening lightweight concrete

    NASA Technical Reports Server (NTRS)

    Auskern, A.

    1972-01-01

    Polymer absorption by lightweight concretes to improve bonding between cement and aggregate and to increase strength of cement is discussed. Compressive strength of treated cement is compared with strength of untreated product. Process for producing polymers is described.

  17. The physical and degradation properties of starch-graft-acrylonitrile/carboxylated nitrile butadiene rubber latex films.

    PubMed

    Misman, M A; Azura, A R; Hamid, Z A A

    2015-09-01

    Starch-graft-acrylonitrile (ANS) is compounded with carboxylated nitrile butadiene rubber (XNBR) latex. The control XNBR and the ANS/XNBR latex films were prepared through a coagulant dipping process. The films were subjected to ageing and soil burial procedures. For the biodegradation experiment, the surface of the film was assessed after the 2nd, 4th and 8th week of soil burial. The ANS, XNBR, and ANS/XNBR colloidal stability were determined with a Malvern Zetasizer. For the dipped latex films, the mechanical, morphological and thermal properties were analyzed. The addition of ANS into the XNBR latex increased the stability of the colloidal dispersions, decreased the latex film tensile strength, but increased the elongation at break due to the bipolar interaction of the ANS and XNBR particles. The ANS/XNBR latex films aged faster than the control films while the morphological analysis showed the existence of a starch crystal region and the formation of microbial colonies on the surfaces of the films. Based on the TGA-DTA curves, a higher ΔT was observed for the ANS/XNBR latex films signifying high thermal energy needed for the film to thermally degrade. PMID:26005134

  18. Latex allergy and occupational asthma in health care workers: adverse outcomes.

    PubMed

    Amr, Sania; Suk, William A

    2004-03-01

    The prevalence of natural rubber latex (NRL) allergy has been estimated to be 5-18% in health care workers, and latex exposure has been one of the leading causes of occupational asthma in the last several years. We present the cases of two nurses who developed sensitivity to NRL, both with dermatologic symptoms and respiratory symptoms that included asthma. They were referred to the University of Maryland for evaluation of their allergies, then for occupational and environmental consults. The patients' allergy to NRL was confirmed on the basis of clinical history, a positive skin test to latex, and the presence of latex-specific immunoglobulin E (IgE) serology by radioallergosorbent test (RAST). Both patients worked in the same community hospital for approximately 20 years; one was an endoscopy nurse and the other worked in the emergency department. Following the diagnosis of allergy to latex, both patients avoided direct skin contact with latex, but they continued to work in the same respective environments, where powdered latex gloves and other potentially sensitizing chemicals were used. Instead of improving, the clinical condition of the patients worsened and they remained symptomatic, even after they were removed from their workplace. Their airways reacted to low levels of a variety of sensitizers and irritants in the environment, and they became depressed. Both nurses were referred for vocational rehabilitation. PMID:14998756

  19. Plant latex: a promising antifungal agent for post harvest disease control.

    PubMed

    Sibi, G; Wadhavan, Rashmi; Singh, Sneha; Shukla, Abhilasha; Dhananjaya, K; Ravikumar, K R; Mallesha, H

    2013-12-01

    Bioactive compounds from plant latex are potential source of antifungic against post harvest pathogens. Latex from a total of seven plant species was investigated for its phytochemical and antifungal properties. Six fungi namely Aspergillus fumigatus, A. niger, A. terreus, F. solani, P. digitatum and R. arrhizus were isolated from infected fruits and vegetables and tested against various solvent extracts of latex. Analysis of latex extracts with phytochemical tests showed the presence of alkaloids, flavonoids, glycosides, phenols, saponins, steroids, tannins and terpenoids. Antifungal assay revealed the potential inhibitory activity of petroleum ether extracts against the postharvest fungal isolates. Various degree of sensitivity was observed irrespective of plant species studied with A. terreus and P. digitatum as the most susceptible ones. F. solani and A. fumigatus were moderately sensitive to the latex extracts tested. Among the plants, latex of Thevetia peruviana (75.2%) and Artocarpus heterophyllus (64.8%) were having potential antifungal activity against the isolates followed by Manilkara zapota (51.1%). In conclusion, use of plant latex makes interest to control postharvest fungal diseases and is fitting well with the concept of safety for human health and environment. PMID:24506041

  20. Charge regulation enables anionic hydroxypropyl guar-borate adsorption onto anionic and cationic polystyrene latex.

    PubMed

    Zhang, Liang; Pelton, Robert; Ketelson, Howard; Meadows, David

    2011-01-15

    Reported are adsorption isotherms for guar and hydroxypropyl guar (HPG), with and without the presence of borate ions, onto surfactant free anionic polystyrene latex. Guar and HPG formed adsorbed monolayers on the hydrophobic latex. The presence of borate ions converted the nonionic guar and HPG into an anionic polyelectrolyte. However, there was no measurable influence of bound borate ions on the adsorption of guar or HPG onto anionic, hydrophobic latex. To underscore the unusual behavior of HPG-borate, a sample of HPG was oxidized to introduce carboxyl groups, and the adsorption of the carboxylated HPG onto anionic polystyrene was measured. Unlike HPG-borate, oxidized HPG did not adsorb onto negative polystyrene latex at neutral pH because of electrostatic repulsion. To explain the adsorption of negative HPG-borate onto negative latex, we proposed that as HPG-borate segments approach the latex surface, the negative electrostatic potential near the latex surface induces the detachment of the labile borate groups from HPG. PMID:21030034

  1. Plant latex: a promising antifungal agent for post harvest disease control.

    PubMed

    Sibi, G; Wadhavan, Rashmi; Singh, Sneha; Shukla, Abhilasha; Dhananjaya, K; Ravikumar, K R; Mallesha, H

    2013-12-01

    Bioactive compounds from plant latex are potential source of antifungic against post harvest pathogens. Latex from a total of seven plant species was investigated for its phytochemical and antifungal properties. Six fungi namely Aspergillus fumigatus, A. niger, A. terreus, F. solani, P. digitatum and R. arrhizus were isolated from infected fruits and vegetables and tested against various solvent extracts of latex. Analysis of latex extracts with phytochemical tests showed the presence of alkaloids, flavonoids, glycosides, phenols, saponins, steroids, tannins and terpenoids. Antifungal assay revealed the potential inhibitory activity of petroleum ether extracts against the postharvest fungal isolates. Various degree of sensitivity was observed irrespective of plant species studied with A. terreus and P. digitatum as the most susceptible ones. F. solani and A. fumigatus were moderately sensitive to the latex extracts tested. Among the plants, latex of Thevetia peruviana (75.2%) and Artocarpus heterophyllus (64.8%) were having potential antifungal activity against the isolates followed by Manilkara zapota (51.1%). In conclusion, use of plant latex makes interest to control postharvest fungal diseases and is fitting well with the concept of safety for human health and environment.

  2. Shear Resistance between Concrete-Concrete Surfaces

    NASA Astrophysics Data System (ADS)

    Kovačovic, Marek

    2013-12-01

    The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

  3. Performance of "Waterless Concrete"

    NASA Technical Reports Server (NTRS)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  4. Grand Rounds: Latex-Induced Occupational Asthma in a Surgical Pathologist

    PubMed Central

    Green-McKenzie, Judith; Hudes, Debra

    2005-01-01

    Context: Latex allergy and sensitization have been an important problem facing health care workers. Providing a latex-safe environment is the intervention of choice. Case Presentation: A 46-year-old surgical pathologist presented with increasing shortness of breath for the previous 4 years. Twenty years before presentation, he noted a pruritic, erythematous rash on his hands, associated with latex glove use. Fourteen years before presentation, during pathology residency, he developed a nonproductive cough, wheezing, and an urticarial rash, temporally associated with use of powdered latex gloves. These symptoms improved while away from work. At presentation, he had one-flight dyspnea. His skin prick test was positive for latex, and pulmonary function testing showed mild obstruction, which was reversible with bronchodilator use. Because the patient was at risk for worsening pulmonary function and possible anaphylaxis with continued exposure, he was removed from the workplace because no reasonable accommodation was made for him at that time. Discussion: The patient’s presentation is consistent with latex-induced occupational asthma. Initially noting dermal manifestations, consistent with an allergic contact dermatitis secondary to accelerators present in latex gloves, he later developed urticaria, flushing, and respiratory symptoms, consistent with a type I hypersensitivity reaction to latex. He also has reversible airways disease, with significant improvement of peak expiratory flow rate and symptoms when away from work. Relevance to Clinical or Professional Practice: The ideal treatment for latex sensitization is removal from and avoidance of exposure. Clinicians should consider occupational asthma when patients present with new-onset asthma or asthmatic symptoms that worsen at work. PMID:16002378

  5. Identification of a 46-kD latex protein allergen in health care workers.

    PubMed Central

    Beezhold, D H; Sussman, G L; Kostyal, D A; Chang, N S

    1994-01-01

    Latex allergy is an occupational hazard for health care workers. Extractable latex proteins are known to be allergenic, but most latex allergens have not been specifically identified. The purpose of this study was to characterize the IgE response of latex-allergic patients to latex proteins and to identify common protein allergens. Serum was obtained from 40 individuals who were skin test-positive to latex; 85% were health care workers. Western blots for IgE reactivity were performed using both ammoniated (AL) and non-ammoniated (NAL) latex proteins and IgE-reactive NAL proteins were analysed by microsequence analysis. The patients were grouped according to common patterns of reactivity. Pattern 1, the most common pattern of reactivity (9/40 patients) recognized two protein bands in both NAL and AL at 46 and 110 kD. A second, heterogeneous pattern of reactivity (pattern 2) recognized a diffuse pattern of polypeptides in the AL preparation. The n-terminal amino acid sequences for allergens at 14, 18, 29, 46 and 110 kD were determined. Sequence analysis identified the 14-kD and 18-kD allergens as the hevein proprotein. The 46-kD and 110-kD had identical sequences which were unique from known latex proteins. We conclude that multiple latex proteins are allergens with hevein preprotein and a previously unidentified 46/110-kD protein being commonly recognized in health care workers. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:7994905

  6. Sucrose importation into laticifers of Hevea brasiliensis, in relation to ethylene stimulation of latex production

    PubMed Central

    Dusotoit-Coucaud, Anaïs; Brunel, Nicole; Kongsawadworakul, Panida; Viboonjun, Unchera; Lacointe, André; Julien, Jean-Louis; Chrestin, Hervé; Sakr, Soulaïman

    2009-01-01

    Background and Aims The major economic product of Hevea brasiliensis is a rubber-containing cytoplasm (latex), which flows out of laticifers (latex cells) when the bark is tapped. The latex yield is stimulated by ethylene. Sucrose, the unique precursor of rubber synthesis, must cross the plasma membrane through specific sucrose transporters before being metabolized in the laticifers. The relative importance of sucrose transporters in determining latex yield is unknown. Here, the effects of ethylene (by application of Ethrel®) on sucrose transporter gene expression in the inner bark tissues and latex cells of H. brasiliensis are described. Methods Experiments, including cloning sucrose transporters, real time RT-PCR and in situ hybridization, were carried out on virgin (untapped) trees, treated or untreated with the latex yield stimulant Ethrel. Key Results Seven putative full-length cDNAs of sucrose transporters were cloned from a latex-specific cDNA library. These transporters belong to all SUT (sucrose transporter) groups and differ by their basal gene expression in latex and inner soft bark, with a predominance of HbSUT1A and HbSUT1B. Of these sucrose transporters, only HbSUT1A and HbSUT2A were distinctly increased by ethylene. Moreover, this increase was shown to be specific to laticifers and to ethylene application. Conclusion The data and all previous information on sucrose transport show that HbSUT1A and HbSUT2A are related to the increase in sucrose import into laticifers, required for the stimulation of latex yield by ethylene in virgin trees. PMID:19567416

  7. Isolation of Macrophage Early and Late Endosomes by Latex Bead Internalization and Density Gradient Centrifugation.

    PubMed

    Lamberti, Giorgia; de Araújo, Mariana E G; Huber, Lukas A

    2015-12-01

    Immortalized macrophage lines and primary macrophages display the ability to internalize small latex beads through the endocytic pathway. This protocol describes a simple and robust method for separating endocytic organelles from macrophages on a sucrose gradient, taking advantage of the significantly lower density of the organelles containing latex beads compared with other intracellular organelles. The latex beads are retained in the endosomes as they mature; therefore, harvesting cells at different time points after internalization permits the purification of different organelle fractions, particularly early and late endosomes. PMID:26631120

  8. Angiogenic activity of latex from Euphorbia tirucalli Linnaeus 1753 (Plantae, Euphorbiaceae).

    PubMed

    Bessa, G; Melo-Reis, P R; Araújo, L A; Mrué, F; Freitas, G B; Brandão, M L; Silva Júnior, N J

    2015-08-01

    To assess the pro-angiogenic activity of Euphorbia tirucalli, commonly known as "avelós" plant, we performed a series of tests by applying an aqueous E. tirucalli latex solution (10 mg/mL) to the chorioallantoic membranes (CAMs) of 80 fertilized chicken eggs incubated in a temperature- and humidity-controlled automatic incubator. The results indicated that the aqueous latex solution increased vascular network formation compared to that with the negative control (p < 0.05) and the inhibitor control (p < 0.05). This suggests that under the experimental conditions tested, the aqueous latex solution induced an inflammatory response leading to neoangiogenesis. PMID:26465734

  9. [Consensus Document. Update on latex exposure and use of gloves in Italian health care settings].

    PubMed

    Crippa, Michela; Balbiani, Lara; Baruffini, Adriana; Belleri, L; Draicchio, F; Feltrin, G; Larese, Francesca; Maggio, G M; Marcer, G; Micheloni, G P; Montomoli, Loretta; Moscato, Gianna; Previdi, M; Sartorelli, P; Sossai, D; Spatari, Giovanna; Zanetti, Caterina

    2008-01-01

    This consensus document was prepared by an Italian working group including occupational health professionals involved for many years in the management of glove- and latex-related problems in health care settings. The aim of this document was to address the most significant technical, epidemiological, clinical, environmental and prevention problems related to the use of gloves and latex. The group's recommendations are based on scientific evidence and practical experience but they cannot be considered as final. These topics need to be periodically revised. The following points should be taken into account: glove quality seems to have improved considerably but the information on glove features provided by the manufacturers is often still inaccurate or incomplete; the regulations in force provide that the manufacturers perform tests to supply evidence for the quality of the products but they do not indicate which analytical method should be used and they do not require that the results be reported in the technical data sheets. Thus the manufacturers have only to declare that their products are "in accordance with the rules"; therefore, purchasers should require the manufacturing companies to supply detailed information and verify their reliability. Moreover, the rules should be adapted to higher quality standards; occupational physicians must be involved for the correct choice and purchase of protective gloves; the use of gloves (in particular latex gloves) and latex devices in health care settings should be based on specific criteria: procedures must be available stating which kind of gloves are suitable for specific tasks. When exposure to latex cannot be avoided it is necessary to choose products that have good biocompatibility (e.g., powder free-gloves with low allergen content); once and for all latex powdered gloves should no longer be commercially available! labels for latex devices (including gloves) should report the extractable latex allergen content. Limit

  10. Investigation of non-isocyanate urethane functional latexes and carbon nanofiller/epoxy coatings

    NASA Astrophysics Data System (ADS)

    Meng, Lei

    This dissertation consists of two parts. In the first part, a new class of non-isocyanate urethane methacrylates was synthesized and the effect of the new monomers on the urethane functional latex was investigated. The second part focused on a comparison of carbon nanofillers in inorganic/organic epoxy coating system for anticorrosive applications. A new class of non-isocyanate urethane methacrylates (UMAs) monomers was synthesized through an environmentally friendly non-isocyanate pathway. The kinetics of seeded semibatch emulsion polymerization of UMAs with methyl methacrylate (MMA) and butyl acrylate (BA) was monitored. The particle size and morphology were investigated by dynamic light scattering (DLS), ultrasound acoustic attenuation spectroscopy (UAAS) and transmission electron microscopy (TEM). The minimum film formation temperature (MFFT), mechanical and viscoelastic properties were studied. It was found that the emulsion polymerization processes all proceeded via Smith-Ewart control, leading to the uniform morphology and particle size. The glass transition temperature (Tg) and the mechanical properties of poly(MMA/BA/UMA) decreased with the increasing chain length of urethane methacrylate monomers due to the increasing flexibility of side chains. Without the effect of Tg, lower MFFT and improved mechanical properties were observed from urethane functional latexes. The improved mechanical properties were due to the increasing particle interaction by forming hydrogen bonding. Furthermore, the effect of urethane functionality in terms of the polymer composition, the location and the concentration was investigated by the batch, single-stage and two-stage semibatch polymerization of 2-[(butylcarbamoyl)oxy]ethyl methacrylate (BEM) with MMA and BA. The core-shell and homogeneous structures were evaluated by TEM, differential scanning calorimetry (DSC), and solid state nuclear magnetic resonance (SS-NMR). The compositional drift was observed from the batch

  11. Astrobib: A Literature Referencing System Compatible with the AAS/WGAS Latex Macros

    NASA Astrophysics Data System (ADS)

    Ferguson, H. C.

    1993-12-01

    Perhaps the most tedious part of preparing an article is dealing with the references: keeping track of which have been cited and formatting the reference section at the end of the paper in accordance with a particular journal's requirements. This package aims to simplify this task, while remaining compatible with the AAS/WGAS latex macros (as well as the latex styles distributed by A&A and MNRAS). For lack of a better name, we call this package Astrobib. The astrobib package can be used on two levels. The first uses the standard ``bibtex'' software to collect all the references cited in the text and format the reference list at the end of the paper according to the style requirements of the Journal. All we have done here is to modify the public-domain ``chicago.bst'' bibtex styles to produce citations in the formats required by ApJ, AJ, A&A, MNRAS, and PASP. All implement, to first order, the formats for references specified in 1992 or 1993 ``Instructions to Authors'' of the different journals. If the paper is rejected by MNRAS, changing three lines will allow it to be printed in ApJ format. The second level overcomes two drawbacks bibtex: the tedious use of braces and commas in bibliography database and the requirement that the author remember citation keys, typically constructed of the authors' initials and the date. With Astrobib the bibliography is kept in a much simpler database (based on the Unix `refer' style) and a couple of Unix-specific programs parse the database into bibtex format and preprocess the text to convert ``loose'' citations into bibtex citation keys. Loose citations allow the author to cite just a few authors (in any order) and perhaps the year or a word of the title of the conference proceedings. Documentation and instructions for electronic access to the package will be available at the meeting. Support for this work was provided by the SERC and by NASA through grant HF1043 awarded by the STScI which is operated by AURA, Inc., for NASA

  12. Mineral oil lubricants cause rapid deterioration of latex condoms.

    PubMed

    Voeller, B; Coulson, A H; Bernstein, G S; Nakamura, R M

    1989-01-01

    As little as sixty seconds' exposure of commercial latex condoms to mineral oil, a common component of hand lotions and other lubricants used during sexual intercourse, caused approximately 90% decrease in the strength of the condoms, as measured by their burst volumes in the standard ISO (International Standards Organization) Air Burst Test. Burst pressures were also reduced, although less dramatically. Lubricants such as Vaseline Intensive Care and Johnson's Baby Oil, each containing mineral oil, also affected condom integrity. Five min. exposure of condoms to glycerol, a frequent component of hand lotions and 'personal lubricants', did not significantly affect burst volume or pressure. Aqueous nonoxynol-9 spermicide did not affect either burst index. The implications of these results for contraception and protection from sexually transmitted diseases, including AIDS, are discussed.

  13. A molecular view of latex-water interfaces

    NASA Astrophysics Data System (ADS)

    Li, Zifeng; Fichthorn, Kristen; Milner, Scott; Yuan, Fang; Larson, Ronald

    2013-03-01

    Latex paints and coatings are colloidal suspensions, in which amorphous polymer particles are dispersed in an aqueous phase. The polymer-water interface plays a key role in the stability and rheology of the suspension. To obtain a molecular level view of this interface, atomistic simulations were performed for a slab of poly(methyl methacrylate)-poly(butyl acrylate) random copolymer in water, focusing on polymer and water density profiles, the hydrogen bonding of water with polymer carbonyl groups, and surface tension. The carbonyl groups at the interface were found to orient significantly towards water. We also calculated the temperature dependence of the surface tension between the polymer/water and polymer/ vacuum interfaces, including tail corrections for cut-off dispersion interactions, and we predict the contact angle of a water droplet at room temperature. Dow Chemical Corporate

  14. Macrocyclic Diterpenoids from the Latex of Euphorbia helioscopia.

    PubMed

    Hua, Juan; Liu, Yan-Chun; Jing, Shu-Xi; Luo, Shi-Hong; Li, Sheng-Hong

    2015-12-01

    One new jatrophane diterpenoid, 7α,9β,15β-triacetoxy-3β-benzoyloxy-14β-hydroxyjatropha-5E,11E-diene (3), together with four known macrocyclic diterpenoids, euphoheliosnoid A (1), epieuphoscopin B (2), euphohelioscopin A (4) and euphoscopin C (5), were isolated from the stem latex of Euphorbia helioscopia. Their structures were established by spectroscopic analyses. In the anti-inflammatory assay, euphohelioscopin A (4) exhibited moderate inhibitory activity on the release of cytokine TNF-α (IC50 = 23.7 ± 1.7 μM), IL-6 (IC50 = 46.1 ± 1.1 μM) and chemokine MCP-1 (IC50 = 33.7 ± 3.8 μM) in lipopolysaccharide (LPS) induced RAW 264.7 macrophages without notable cytotoxicity (IC50 > 80 μM). PMID:26882659

  15. Latex-like water-borne polyaniline for coating applications

    SciTech Connect

    Liu, H.; Clark, R.; Yang, S.C.

    1998-07-01

    The authors report the synthesis of a polymeric complex of polyaniline that is dispersed in water as a stable suspension. The polymer, PAN:PVME-MLA, is a molecular complex of polyaniline and poly(vinylmethylether-co-maleic acid). The synthetic process leads to a stable latex-like suspension in water. The water-borne conducting polymer, once dried as a thin film on a substrate, is not dissolvable by water or other solvents. An example of piece-dyeing process is presented to show its potential for electrostatic dissipation of textile products. Another example illustrates that the material may be used as electroactive thin-films for electrochromic windows and for rechargeable battery applications.

  16. SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS.

    SciTech Connect

    BERNDT,M.L.

    2004-06-01

    fibers. The use of recycled concrete aggregate in the conventional and 50% slag mixes was also studied. Properties investigated included compressive and tensile strengths, elastic modulus, coefficient of permeability, thermal conductivity and durability in seawater and sulfate solutions. It was determined that the mixes containing 50% slag gave the best overall performance. Slag was particularly beneficial for concrete that used recycled aggregate and could reduce strength losses. Initial durability results indicated that corrosion of fibers in the different concrete mixes when exposed to seawater was minimal. Future research needs to include more detailed studies of mix design and properties of concrete for wind turbine foundations. Emphasis on slag-modified mixes with natural and recycled concrete aggregate is recommended. The proportion of slag that can be incorporated in the concrete needs to be optimized, as does the grading of recycled aggregate. The potential for using silica fume in conjunction with slag is worth exploring as this may further enhance strength and durability. Longer-term durability studies are necessary and other pertinent properties of concrete that require investigation include damping characteristics, pullout strength, fatigue strength and risk of thermal cracking. The properties of sustainable concrete mixes need to be integrated with studies on the structural behavior of wind turbine foundations in order to determine the optimal mix design and to examine means of reducing conservatism and cost of foundations.

  17. Liquid marbles stabilized by charged polymer latexes: how does the drying of the latex particles affect the properties of liquid marbles?

    PubMed

    Sun, Guanqing; Sheng, Yifeng; Wu, Jie; Ma, Guanghui; Ngai, To

    2014-10-28

    The coating of solid particles on the surface of liquid in air makes liquid marbles a promising approach in the transportation of a small amount of liquid. The stabilization of liquid marbles by polymeric latex particles imparts extra triggers such as pH and temperature, leading to the remote manipulation of droplets for many potential applications. Because the functionalized polymeric latexes can exist either as colloidally stable latex or as flocculated latex in a dispersion, the drying of latex dispersions under different conditions may play a significant role in the stabilization of subsequent liquid marbles. This article presents the investigation of liquid marbles stabilized by poly(styrene-co-methacrylic acid) (PS-co-MAA) particles drying under varied conditions. Protonation of the particles before freeze drying makes the particles excellent liquid marble stabilizers, but it is hard to stabilize liquid marbles for particles dried in their deprotonated states. The static properties of liquid marbles with increasing concentrations of protonating reagent revealed that the liquid marbles are gradually undermined by protonating the stabilizers. Furthermore, the liquid marbles stabilized by different particles showed distinct behaviors in separation and merging manipulated by tweezers. This study shows that the initial state of the particles should be carefully taken into account in formulating liquid marbles.

  18. The Investigation of Properties of Insulating Refractory Concrete with Portland Cement Binder

    NASA Astrophysics Data System (ADS)

    Kudžma, A.; Antonovič, V.; Stonys, R.; Škamat, J.

    2015-11-01

    The present work contains the results of experimental study on properties of insulating refractory concrete created on the basis of Portland cement (PC) binder and modified with microsilica (MS). The experimental compositions were made using Portland cement, lightweight aggregates (expanded clay and vermiculite) and microsilica additives. It was established that MS additives enable significant improvement of mechanical properties and thermal shock resistance of PC-based insulating concrete with values comparable to insulating refractory concrete based on calcium aluminate cement.

  19. [Preparation of magnetic latexes and their use for the immunodetection of microbial antigens].

    PubMed

    Kal'noĭ, S M; Zharnikova, I V; Zaĭtsev, A A; Bondarenko, A I; Borzdova, I Iu; Ostapovich, V V; Kurilova, A A

    2010-01-01

    The possibility of detecting antigens of plague, tularemia, and brucellosis microbes with magnetic latex (ML)-based test systems has been demonstrated. MLs were prepared from latexes (polyacroleine microspheres, 1.2-1.8 +/- 0.1 microm) by exposing the particles to a 25-35%-solution of ferrous sulfate for 0.5 h and then to a 15-25%-aqueous solution of ammonia for 0.5 h in a 100 degrees C water bath and dehydrating after each operation. The possibility of preparing magnetic latex immunosorbents (MLIS) by ligand immobilization on ML and using them in magnetic latex ELISA (ML-ELISA) for the detection of microbial antigens was demonstrated. The detection limit in ML-ELISA equaled 10(2)-10(3) microbial cells in 1 ml (cells/ml). Relative experimental error was not higher than 8%.

  20. Phagocytosis of latex beads by alveolar macrophages from mice exposed to cigarette smoke.

    PubMed

    Ortega, E; Hueso, F; Collazos, M E; Pedrera, M I; Barriga, C; Rodríguez, A B

    1992-04-01

    Cigarette smoking is known to alter the numerical presence and function of alveolar macrophages. It has been speculated that these cigarette-smoke-induced alterations contribute to the depressed pulmonary defence mechanism commonly demonstrated in smokers. Studies of the phagocytic and bactericidal activities of alveolar macrophages from smokers and non-smokers have yielded conflicting results. The purpose of this study was to investigate the phagocytic capacity of alveolar macrophages from mice exposed to cigarette smoke in relation to the ability to ingest inert particles (latex beads). Measurements were made before (basal values), immediately after, and 1, 12 or 24 h after exposure. Significant decreases were observed in the number of latex beads ingested by 100 macrophages (phagocytic index) and in the phagocytic efficiency for ingesting latex (mean number of latex beads ingested per activated macrophages) immediately after and 1 h after exposure, and in the number of activated macrophages (those with phagocytic activity) immediately after exposure. PMID:1563261

  1. Extraction and characterization of a natural rubber from Euphorbia characias latex.

    PubMed

    Spanò, Delia; Pintus, Francesca; Mascia, Claudia; Scorciapino, Mariano Andrea; Casu, Mariano; Floris, Giovanni; Medda, Rosaria

    2012-08-01

    A natural rubber was identified and characterized for the first time in the latex of the perennial Mediterranean shrub Euphorbia characias. Four different methods, i.e., acetone, acetic acid, trichloroacetic acid, and Triton® X-100, followed by successive treatments with cyclohexane/ethanol, were employed to extract the natural rubber. The rubber content was shown to be 14% (w/v) of the E. characias latex, a low content compared with that of Hevea brasiliensis (30-35%) but a similar content to other rubber producing plants. E. characias rubber showed a molecular weight of 93,000 with a M(w) /M(n) of 2.9. (1) H NMR, (13) C NMR, and FTIR analysis revealed the characteristic of the cis-1,4-polyisoprene typical of natural rubber. These results provided novel insight into latex components and will ultimately benefit the broader understanding of E. characias latex composition.

  2. Determination of the coalescence temperature of latexes by environmental scanning electron microscopy.

    PubMed

    Gonzalez, Edurne; Tollan, Christopher; Chuvilin, Andrey; Barandiaran, Maria J; Paulis, Maria

    2012-08-01

    A new methodology for quantitative characterization of the coalescence process of waterborne polymer dispersion (latex) particles by environmental scanning electron microscopy (ESEM) is proposed. The experimental setup has been developed to provide reproducible latex monolayer depositions, optimized contrast of the latex particles, and a reliable readout of the sample temperature. Quantification of the coalescence process under dry conditions has been performed by image processing based on evaluation of the image autocorrelation function. As a proof of concept the coalescence of two latexes with known and differing glass transition temperatures has been measured. It has been shown that a reproducibility of better than 1.5 °C can be obtained for the measurement of the coalescence temperature.

  3. Transport properties of self-consolidating concrete

    SciTech Connect

    Sonebi, M.; Nanukuttan, S.

    2009-03-15

    This study reports the findings from an investigation carried out to study the effect of the mixture variations on the durability of medium- and high-strength self-consolidating concrete (SCC). The mixture variations studied include the type of mineral admixtures, such as limestone powder (LSP) and pulverized fuel ash (PFA), and viscosity-modifying admixtures (VMA) for both medium- and high-strength SCC. Air permeability, water permeability, capillary absorption, and chloride diffusivity were used to assess the durability of SCC mixtures in comparison with normal, vibrated concretes. The results showed that SCC mixtures, for medium- and high-strength grades using PFA followed by LSP give lower permeability, properties compared with normal concretes. SCC made with VMA had a higher sorptivity, air permeability, and water permeability compared with other SCC mixtures, which can be attributed to higher water-cement ratio (w/c) and lack of pore filling effect. An in-place migration coefficient was obtained using the in-place ion migration test. This was used to compare the potential diffusivity of different concretes. The results indicated that SCC, for both grades of strength, made with PFA showed much lower diffusivity values in comparison with other mixtures, whereas the SCC mixtures with VMA showed higher diffusivity.

  4. 26. Evening view of concrete mixing plant, concrete placement tower, ...

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

    26. Evening view of concrete mixing plant, concrete placement tower, cableway tower, power line and derrick. Photographer unknown, 1927. Source: MWD. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  5. 10. CONCRETE BRIDGE, REINFORCED BEAM TYPE ON CONCRETE, SOUTH CAROLINA ...

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

    10. CONCRETE BRIDGE, REINFORCED BEAM TYPE ON CONCRETE, SOUTH CAROLINA STATE HIGHWAY DEPARTMENT, COLUMBIA, SOUTH CAROLINA (photocopy of drawing) - Salkehatchie Bridge, State Route No. 64 spanning Salkehatchie River, Barnwell, Barnwell County, SC

  6. Earthquake safety assessment of concrete arch and gravity dams

    NASA Astrophysics Data System (ADS)

    Lin, Gao; Hu, Zhiqiang

    2005-12-01

    Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessment of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrete subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range. Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods.

  7. Design of polystyrene latex particles covered with polyoxometalate clusters via multiple covalent bonding

    SciTech Connect

    Chen, Xinyue; Li, Hui; Yin, Panchao; Liu, Tianbo

    2015-02-27

    In this study, polyoxometalates (POMs) covalently functionalized with methyl methacrylate groups were applied as surfactants in the emulsion polymerization reaction of styrene. Due to the copolymerization of the methyl methacrylate groups and the styrene monomers, the polyoxometalate clusters are covalently grafted onto the surface of polystyrene latex nanoparticles. Finally, such latex particles are fully covered with catalytic POM clusters and might serve as quasi-homogeneous catalysts.

  8. Design of polystyrene latex particles covered with polyoxometalate clusters via multiple covalent bonding.

    PubMed

    Chen, Xinyue; Li, Hui; Yin, Panchao; Liu, Tianbo

    2015-04-11

    Polyoxometalates (POMs) covalently functionalized with methyl methacrylate groups were applied as surfactants in the emulsion polymerization reaction of styrene. Due to the copolymerization of the methyl methacrylate groups and the styrene monomers, the polyoxometalate clusters are covalently grafted onto the surface of polystyrene latex nanoparticles. Such latex particles are fully covered with catalytic POM clusters and might serve as quasi-homogeneous catalysts. PMID:25743436

  9. Capacitance Regression Modelling Analysis on Latex from Selected Rubber Tree Clones

    NASA Astrophysics Data System (ADS)

    Rosli, A. D.; Hashim, H.; Khairuzzaman, N. A.; Mohd Sampian, A. F.; Baharudin, R.; Abdullah, N. E.; Sulaiman, M. S.; Kamaru'zzaman, M.

    2015-11-01

    This paper investigates the capacitance regression modelling performance of latex for various rubber tree clones, namely clone 2002, 2008, 2014 and 3001. Conventionally, the rubber tree clones identification are based on observation towards tree features such as shape of leaf, trunk, branching habit and pattern of seeds texture. The former method requires expert persons and very time-consuming. Currently, there is no sensing device based on electrical properties that can be employed to measure different clones from latex samples. Hence, with a hypothesis that the dielectric constant of each clone varies, this paper discusses the development of a capacitance sensor via Capacitance Comparison Bridge (known as capacitance sensor) to measure an output voltage of different latex samples. The proposed sensor is initially tested with 30ml of latex sample prior to gradually addition of dilution water. The output voltage and capacitance obtained from the test are recorded and analyzed using Simple Linear Regression (SLR) model. This work outcome infers that latex clone of 2002 has produced the highest and reliable linear regression line with determination coefficient of 91.24%. In addition, the study also found that the capacitive elements in latex samples deteriorate if it is diluted with higher volume of water.

  10. Oral dosing with papaya latex is an effective anthelmintic treatment for sheep infected with Haemonchus contortus

    PubMed Central

    2011-01-01

    Background The cysteine proteinases in papaya latex have been shown to have potent anthelmintic properties in monogastric hosts such as rodents, pigs and humans, but this has not been demonstrated in ruminants. Methods In two experiments, sheep were infected concurrently with 5,000 infective larvae of Haemonchus contortus and 10,000 infective larvae of Trichostrongylus colubriformis and were then treated with the supernatant from a suspension of papaya latex from day 28 to day 32 post-infection. Faecal egg counts were monitored from a week before treatment until the end of the experiment and worm burdens were assessed on day 35 post-infection. Results We found that the soluble fraction of papaya latex had a potent in vivo effect on the abomasal nematode H. contortus, but not on the small intestinal nematode T. colubriformis. This effect was dose-dependent and at tolerated levels of gavage with papaya latex (117 μmol of active papaya latex supernatant for 4 days), the H. contortus worm burdens were reduced by 98%. Repeated treatment, daily for 4 days, was more effective than a single dose, but efficacy was not enhanced by concurrent treatment with the antacid cimetidine. Conclusions Our results provide support for the idea that cysteine proteinases derived from papaya latex may be developed into novel anthelmintics for the treatment of lumenal stages of gastro-intestinal nematode infections in sheep, particularly those parasitizing the abomasum. PMID:21406090

  11. Enhanced protein adsorption and patterning on nanostructured latex-coated paper.

    PubMed

    Juvonen, Helka; Määttänen, Anni; Ihalainen, Petri; Viitala, Tapani; Sarfraz, Jawad; Peltonen, Jouko

    2014-06-01

    Specific interactions of extracellular matrix proteins with cells and their adhesion to the substrate are important for cell growth. A nanopatterned latex-coated paper substrate previously shown to be an excellent substrate for cell adhesion and 2D growth was studied for directed immobilization of proteins. The nanostructured latex surface was formed by short-wavelength IR irradiation of a two-component latex coating consisting of a hydrophilic film-forming styrene butadiene acrylonitrile copolymer and hydrophobic polystyrene particles. The hydrophobic regions of the IR-treated latex coating showed strong adhesion of bovine serum albumin (cell repelling protein), fibronectin (cell adhesive protein) and streptavidin. Opposite to the IR-treated surface, fibronectin and streptavidin had a poor affinity toward the untreated pristine latex coating. Detailed characterization of the physicochemical surface properties of the latex-coated substrates revealed that the observed differences in protein affinity were mainly due to the presence or absence of the protein repelling polar and charged surface groups. The protein adsorption was assisted by hydrophobic (dehydration) interactions.

  12. Latex Rubber Gloves as a Sampling Dosimeter Using a Novel Surrogate Sampling Device.

    PubMed

    Sankaran, Gayatri; Lopez, Terry; Ries, Steve; Ross, John; Vega, Helen; Eastmond, David A; Krieger, Robert I

    2015-01-01

    Pesticide exposure during harvesting of crops occurs primarily to the workers' hands. When harvesters wear latex rubber gloves for personal safety and hygiene harvesting reasons, gloves accumulate pesticide residues. Hence, characterization of the gloves' properties may be useful for pesticide exposure assessments. Controlled field studies were conducted using latex rubber gloves to define the factors that influence the transfer of pesticides to the glove and that would affect their use as a residue monitoring device. A novel sampling device called the Brinkman Contact Transfer Unit (BCTU) was constructed to study the glove characteristics and residue transfer and accumulation under controlled conditions on turf. The effectiveness of latex rubber gloves as sampling dosimeters was evaluated by measuring the transferable pesticide residues as a function of time. The validation of latex rubber gloves as a residue sampling dosimeter was performed by comparing pesticide transfer and dissipation from the gloves, with the turf transferable residues sampled using the validated California (CA) Roller, a standard measure of residue transfer. The observed correlation (Pearson's correlation coefficient R(2)) between the two methods was .84 for malathion and .96 for fenpropathrin, indicating that the BCTU is a useful, reliable surrogate tool for studying available residue transfer to latex rubber gloves under experimental conditions. Perhaps more importantly, these data demonstrate that latex gloves worn by workers may be useful quantifiable matrices for measuring pesticide exposure.

  13. Physical Methods for the Preparation of Hybrid Nanocomposite Polymer Latex Particles

    NASA Astrophysics Data System (ADS)

    Teixeira, Roberto F. A.; Bon, Stefan A. F.

    In this chapter, we will highlight conceptual physical approaches towards the fabrication of nanocomposite polymer latexes in which each individual latex particle contains one or more "hard" nanoparticles, such as clays, silicates, titanates, or other metal(oxides). By "physical approaches" we mean that the "hard" nanoparticles are added as pre-existing entities, and are not synthesized in situ as part of the nanocomposite polymer latex fabrication process. We will narrow our discussion to focus on physical methods that rely on the assembly of nanoparticles onto the latex particles after the latex particles have been formed, or its reciprocal analogue, the adhesion of polymer onto an inorganic nanoparticle. First, will discuss the phenomenon of heterocoagulation and its various driving forces, such as electrostatic interactions, the hydrophobic effect, and secondary molecular interactions. We will then address methods that involve assembly of nanoparticles onto or around the more liquid precursors (i.e., swollen/growing latex particles or monomer droplets). We will focus on the phenomenon of Pickering stabilization. We will then discuss features of particle interaction with soft interfaces, and see how the adhesion of particles onto emulsion droplets can be applied in suspension, miniemulsion, and emulsion polymerization. Finally, we will very briefly mention some interesting methods that make use of interface-driven templating for making well-defined assembled clusters and supracolloidal structures.

  14. Electrokinetic decontamination of concrete

    SciTech Connect

    Lomasney, H.

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  15. Deposition kinetics of quantum dots and polystyrene latex nanoparticles onto alumina: role of water chemistry and particle coating.

    PubMed

    Quevedo, Ivan R; Olsson, Adam L J; Tufenkji, Nathalie

    2013-03-01

    A clear understanding of the factors controlling the deposition behavior of engineered nanoparticles (ENPs), such as quantum dots (QDs), is necessary for predicting their transport and fate in natural subsurface environments and in water filtration processes. A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the effect of particle surface coatings and water chemistry on the deposition of commercial QDs onto Al2O3. Two carboxylated QDs (CdSe and CdTe) with different surface coatings were compared with two model nanoparticles: sulfate-functionalized (sPL) and carboxyl-modified (cPL) polystyrene latex. Deposition rates were assessed over a range of ionic strengths (IS) in simple electrolyte (KCl) and in electrolyte supplemented with two organic molecules found in natural waters; namely, humic acid and rhamnolipid. The Al2O3 collector used here is selected to be representative of oxide patches found on the surface of aquifer or filter grains. Deposition studies showed that ENP deposition rates on bare Al2O3 generally decreased with increasing salt concentration, with the exception of the polyacrylic-acid (PAA) coated CdTe QD which exhibited unique deposition behavior due to changes in the conformation of the PAA coating. QD deposition rates on bare Al2O3 were approximately 1 order of magnitude lower than those of the polystyrene latex nanoparticles, likely as a result of steric stabilization imparted by the QD surface coatings. Adsorption of humic acid or rhamnolipid on the Al2O3 surface resulted in charge reversal of the collector and subsequent reduction in the deposition rates of all ENPs. Moreover, the ratio of the two QCM-D output parameters, frequency and dissipation, revealed key structural information of the ENP-collector interface; namely, on bare Al2O3, the latex particles were rigidly attached as compared to the more loosely attached QDs. This study emphasizes the importance of considering the nature of ENP coatings as well

  16. Heidrun concrete TLP: Update

    SciTech Connect

    Munkejord, T.

    1995-10-01

    This paper gives a summary of the Heidrun substructure including tethers and foundations. The focus will although be on the concrete substructure. The Heidrun Field is located in 345 m water depth in the northern part of the Haltenbanken area, approximately 100N miles from the west coast of mid-Norway. The field is developed by means of a concrete Tension Leg Platform (TLP) by Conoco Norway Inc. The TLP will be moored by 16 steel tethers, arranged in groups of four per corner, which secure the substructure (hull) to the concrete foundations. A general view of the TLP is shown. The Heidrun TLP will be the northern most located platform in the North Sea when installed at Haltenbanken in 1995. Norwegian Contractors a.s (NC) is undertaking the Engineering, Procurement, Construction and Installation (EPCI) contract for the Heidrun TLP substructure. This comprises the complete delivery of the hull with two module support beams (MSB), including all mechanical outfitting. Furthermore, NC will perform all marine operations related to the substructure. For the concrete foundations NC has performed the detailed engineering work and has been responsible for the two to field and installation of the foundations.

  17. High temperature polymer concrete

    DOEpatents

    Fontana, J.J.; Reams, W.

    1984-05-29

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

  18. Electroosmotic decontamination of concrete

    SciTech Connect

    Bostick, W.D.; Bush, S.A.; Marsh, G.C.; Henson, H.M.; Box, W.D.; Morgan, I.L.

    1993-03-01

    A method is described for the electroosmotic decontamination of concrete surfaces, in which an electrical field is used to induce migration of ionic contaminants from porous concrete into an electrolyte solution that may be disposed of as a low-level liquid radioactive waste (LLRW); alternately, the contaminants from the solution can be sorbed onto anion exchange media in order to prevent contaminant buildup in the solution and to minimize the amount of LLRW generated. We have confirmed the removal of uranium (and infer the removal of {sup 99}Tc) from previously contaminated concrete surfaces. In a typical experimental configuration, a stainless steel mesh is placed in an electrolyte solution contained within a diked cell to serve as the negative electrode (cathode) and contaminant collection medium, respectively, and an existing metal penetration (e.g., piping, conduit, or rebar reinforcement within the concrete surface) serves as the positive electrode (anode) to complete the cell. Typically we have achieved 70 to >90% reductions in surface activity by applying <400 V and <1 A for 1--3 h (energy consumption of 0.4--12 kWh/ft{sup 2}).

  19. Variables that affect the mechanism of drug release from osmotic pumps coated with acrylate/methacrylate copolymer latexes.

    PubMed

    Jensen, J L; Appel, L E; Clair, J H; Zentner, G M

    1995-05-01

    The feasibility of using modified Eudragit acrylic latexes as microporous coatings for osmotic devices was investigated. Potassium chloride tablets were coated with mixtures of Eudragit RS30D and RL30D acrylic latexes that also contained a plasticizer (triethyl citrate or acetyl tributyl citrate) and a pore-forming agent (urea). A 2(5-1) fractional factorial experimental design was employed to determine the effect of five formulation variables (RS30D:RL30D polymer ratio plasticizer type, plasticizer level, urea level, and cure) on the in vitro release rate of KCl in deionized water (di water), lag time, and coat burst strength. The RS30D:RL30D polymer ratio had the greatest effect on the release rate, and both lag time and burst strength were most affected by the urea level. Statistical optimization was performed, and a coat formulation with predicted desirable in vitro performance was prepared and tested. The in vitro release rate (di water), lag time, and coat burst strength agreed well with the prediction. Dissolutions were also performed in phosphate buffered saline (PBS; pH 7.4); several formulations released markedly slower in PBS than in di water. This discrepancy was dependent on the type of plasticizer and the amount of pore former. Only those coat formulations containing acetyl tributyl citrate as the plasticizer and a 100% urea [(g urea/g polymer solids) x 100] level exhibited similar release rates in di water and PBS. The mechanism of release from these devices was primarily osmotic, whereas the release from devices coated with a formulation containing triethyl citrate and 50% urea was not dependent on the osmotic pressure difference. Devices with an osmotic release mechanism behaved similarly in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7658339

  20. Variables that affect the mechanism of drug release from osmotic pumps coated with acrylate/methacrylate copolymer latexes.

    PubMed

    Jensen, J L; Appel, L E; Clair, J H; Zentner, G M

    1995-05-01

    The feasibility of using modified Eudragit acrylic latexes as microporous coatings for osmotic devices was investigated. Potassium chloride tablets were coated with mixtures of Eudragit RS30D and RL30D acrylic latexes that also contained a plasticizer (triethyl citrate or acetyl tributyl citrate) and a pore-forming agent (urea). A 2(5-1) fractional factorial experimental design was employed to determine the effect of five formulation variables (RS30D:RL30D polymer ratio plasticizer type, plasticizer level, urea level, and cure) on the in vitro release rate of KCl in deionized water (di water), lag time, and coat burst strength. The RS30D:RL30D polymer ratio had the greatest effect on the release rate, and both lag time and burst strength were most affected by the urea level. Statistical optimization was performed, and a coat formulation with predicted desirable in vitro performance was prepared and tested. The in vitro release rate (di water), lag time, and coat burst strength agreed well with the prediction. Dissolutions were also performed in phosphate buffered saline (PBS; pH 7.4); several formulations released markedly slower in PBS than in di water. This discrepancy was dependent on the type of plasticizer and the amount of pore former. Only those coat formulations containing acetyl tributyl citrate as the plasticizer and a 100% urea [(g urea/g polymer solids) x 100] level exhibited similar release rates in di water and PBS. The mechanism of release from these devices was primarily osmotic, whereas the release from devices coated with a formulation containing triethyl citrate and 50% urea was not dependent on the osmotic pressure difference. Devices with an osmotic release mechanism behaved similarly in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Sensitisation to natural rubber latex: an epidemiological study of workers exposed during tapping and glove manufacture in Thailand

    PubMed Central

    Chaiear, N; Sadhra, S; Jones, M; Cullinan, P; Foulds, I; Burge, P

    2001-01-01

    OBJECTIVES—To estimate the prevalence of sensitisation to natural rubber latex in latex tappers and latex glove factory workers, and to relate this to airborne exposure to latex.
METHODS—Five hundred workers employed in three latex glove factories, 314 tappers, and 144 college students (control group) were studied. The workers in the glove factories were classified into three exposure groups; high, moderate, and low. Personal exposures to natural rubber latex aeroallergens were measured by immunoassay. Symptom questionnaires and skin prick tests with latex allergens (Stallergènes 1:200 w/v) and other common environmental allergens were performed. The criterion for positivity was a wheal reaction at least 3 mm in diameter greater than that to a diluent control.
RESULTS—The geometric mean (GM) concentration of latex in air was 15.4 µg/m3 for those employed in glove stripping, glove inspections, and packing of powdered gloves. The moderate exposure glove manufacturing group and the tappers had GM concentrations of 2.3 and 2.4 µg/m3 respectively, compared with United Kingdom users of latex powdered gloves,who had GM concentrations of 0.5 µg/m3. The prevalence of sensitisation to latex in the tappers and latex glove factory workers was 1.3% and 1.7% respectively. No positive cases were found among the college students. Workers who showed a positive skin prick test to latex were more likely to be atopic. Work related respiratory and dermatological symptoms were found in about 20% of each population studied, but were not related to the presence of positive latex prick tests.
CONCLUSIONS—This study suggests that in the Thai latex industries, latex sensitisation is rare despite high concentrations of airborne exposure and is less prevalent than in the healthcare sector in Europe where skin exposure is greater. 


Keywords: natural rubber; latex; allergy; glove factory; healthcare PMID:11351054

  2. Impacts of bridging complexation on the transport of surface-modified nanoparticles in saturated sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transport of polyacrylic acid capped cadmium telluride (CdTe) quantum dots (QDs) and carboxylate-modified latex (CML) nanoparticles (NPs) was studied in packed columns at various electrolyte concentrations and cation types. The breakthrough curves (BTCs) of QDs and CML NPs in acid-treated Accus...

  3. Using Modeling to Design new Rheology Modifiers for Paints

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy

    2013-03-01

    Since their invention in 1970-s, hydrophobically ethoxylated urethanes (HEUR) have been actively used as rheology modifiers for paints. Thermodynamic and rheological behavior of HEUR molecules in aqueous solutions is now very well understood and is based on the concept of transient network (TN), where the association of hydrophobic groups into networks of flower micelles causes viscosity to increase dramatically as function of polymer concentration. The behavior of complex mixtures containing water, HEUR, and latex (``binder'') particles, however, is understood less well, even though it has utmost importance in the paint formulation design. In this talk, we discuss how the adsorption of HEUR chains onto latex particles results in formation of complex viscoelastic networks with temporary bridges between particles. We then utilize Self-Consistent Field Theory (SCFT) model to compute effective adsorption isotherms (thickener-on-latex) and develop a rheological theory describing steady-shear viscosity of such mixtures. The model is able to qualitatively describe many important features of the water/latex/HEUR mixtures, such as strong shear thinning. The proposed approach could potentially lead to the design of new HEUR structures with improved rheological performance. This work was supported by Dow Chemical Company

  4. Ciprofloxacin release using natural rubber latex membranes as carrier.

    PubMed

    Dias Murbach, Heitor; Jaques Ogawa, Guilherme; Azevedo Borges, Felipe; Romeiro Miranda, Matheus Carlos; Lopes, Rute; Roberto de Barros, Natan; Guedes Mazalli, Alexandre Vinicius; Gonçalves da Silva, Rosângela; Ferreira Cinman, José Luiz; de Camargo Drago, Bruno; Donizetti Herculano, Rondinelli

    2014-01-01

    Natural rubber latex (NRL) from Hevea brasiliensis is easily manipulated, low cost, is of can stimulate natural angiogenesis and cellular adhesion, is a biocompatible, material and presents high mechanical resistance. Ciprofloxacin (CIP) is a synthetic antibiotic (fluoroquinolone) used in the treatment of infection at external fixation screws sites and remote infections, and this use is increasingly frequent in medical practice. The aim of this study was to develop a novel sustained delivery system for CIP based on NRL membranes and to study its delivery system behavior. CIP was found to be adsorbed on the NRL membrane, according to results of energy dispersive X-ray spectroscopy. Results show that the membrane can release CIP for up to 59.08% in 312 hours and the mechanism is due to super case II (non-Fickian). The kinetics of the drug release could be fitted with double exponential function X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy shows some interaction by hydrogen bound, which influences its mechanical behavior. PMID:25587278

  5. Latex micro-balloon pumping in centrifugal microfluidic platforms.

    PubMed

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Al-Faqheri, Wisam; Thio, Tzer Hwai Gilbert; Kazemzadeh, Amin; Madou, Marc

    2014-03-01

    Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon.

  6. Polyphenol oxidases from latex of Hevea brasiliensis: purification and characterization.

    PubMed

    Wititsuwannakul, Dhirayos; Chareonthiphakorn, Nopphakaew; Pace, Mario; Wititsuwannakul, Rapepun

    2002-09-01

    Polyphenol oxidase (PPO) was isolated from the B-serum obtained after repetitive freeze-thawing of the bottom fraction isolated from ultracentrifuged fresh latex. The B-serum was subjected to acetone precipitation and CM-Sepharose chromatography, affording two PPOs, PPO-I and PPO-II, which, upon SDS-PAGE, were 32 and 34 kDa, respectively. Both PPOs possessed the same pI (9.2), optimum pH (7) and optimum temperature (35-45 degrees C). They are stable up to 60 degrees C and active at broad pH ranges from 4-9. The K(m) values of PPO-I for dopamine, L-dopa and catechol as substrates are 2.08, 8.33 and 9.09 mM, while those for PPO-II are 2.12, 4.76 and 7.14 mM, respectively. Among various PPO inhibitors tested, 4-hexylresorcinol was the most potent. Anionic detergents were among the most effective activators of the enzymes, while cationic and nonionic detergents showed little and no effect on the PPO activities, respectively. PMID:12169303

  7. Interaction of latex colloids with mineral surfaces and Grimsel granodiorite.

    PubMed

    Filby, A; Plaschke, M; Geckeis, H; Fanghänel, Th

    2008-12-12

    Bentonite clay is considered as possible backfill material for nuclear waste repositories in crystalline rock. The same material may also be a source of clay colloids, which may act as carriers for actinide ions possibly released from the repository. Depending on the geochemical parameters, these colloids may be retained by interaction with mineral surfaces of the host rock. In the present study interaction of carboxylated fluorescent latex colloids, used as a model for bentonite colloids, with natural Grimsel granodiorite and some of its component minerals is studied by fluorescence microscopy and SEM/EDX. The experiments are carried out by varying the pH from 2-10. Strong adsorption is observed at pH values close to or below the points of zero charge (pHpzc) of the mineral surfaces. The influence of Eu(III), used as a chemical homologue for trivalent actinide ions, on colloid adsorption is investigated. Depending on mineral phase and pH, a significant increase of colloid adsorption is observed in the presence of Eu(III).

  8. Ciprofloxacin Release Using Natural Rubber Latex Membranes as Carrier

    PubMed Central

    Dias Murbach, Heitor; Azevedo Borges, Felipe; Romeiro Miranda, Matheus Carlos; Lopes, Rute; Roberto de Barros, Natan; Guedes Mazalli, Alexandre Vinicius; Gonçalves da Silva, Rosângela; Ferreira Cinman, José Luiz; de Camargo Drago, Bruno; Donizetti Herculano, Rondinelli

    2014-01-01

    Natural rubber latex (NRL) from Hevea brasiliensis is easily manipulated, low cost, is of can stimulate natural angiogenesis and cellular adhesion, is a biocompatible, material and presents high mechanical resistance. Ciprofloxacin (CIP) is a synthetic antibiotic (fluoroquinolone) used in the treatment of infection at external fixation screws sites and remote infections, and this use is increasingly frequent in medical practice. The aim of this study was to develop a novel sustained delivery system for CIP based on NRL membranes and to study its delivery system behavior. CIP was found to be adsorbed on the NRL membrane, according to results of energy dispersive X-ray spectroscopy. Results show that the membrane can release CIP for up to 59.08% in 312 hours and the mechanism is due to super case II (non-Fickian). The kinetics of the drug release could be fitted with double exponential function X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy shows some interaction by hydrogen bound, which influences its mechanical behavior. PMID:25587278

  9. A new test procedure for biogenic sulfuric acid corrosion of concrete

    PubMed

    Vincke; Verstichel; Monteny; Verstraete

    1999-01-01

    A new test method is described for biogenic sulfuric acid corrosion of concrete, more specifically in sewer conditions. The aim of the new test method is the development of an accelerated and reproducible procedure for monitoring the resistance of different types of concrete with regard to biogenic sulfuric acid corrosion. This experimental procedure reflects worst case conditions by providing besides H2S, also an enrichment of thiobacilli and biologically produced sulfur. By simulating the cyclic processes occurring in sewer pipes, significant differences between concrete mixtures could be detected after 51 days. Concrete modified by a styrene-acrylic ester polymer demonstrated a higher resistance against biogenic sulfuric acid attack. PMID:11068828

  10. A new test procedure for biogenic sulfuric acid corrosion of concrete

    PubMed

    Vincke; Verstichel; Monteny; Verstraete

    1999-01-01

    A new test method is described for biogenic sulfuric acid corrosion of concrete, more specifically in sewer conditions. The aim of the new test method is the development of an accelerated and reproducible procedure for monitoring the resistance of different types of concrete with regard to biogenic sulfuric acid corrosion. This experimental procedure reflects worst case conditions by providing besides H2S, also an enrichment of thiobacilli and biologically produced sulfur. By simulating the cyclic processes occurring in sewer pipes, significant differences between concrete mixtures could be detected after 51 days. Concrete modified by a styrene-acrylic ester polymer demonstrated a higher resistance against biogenic sulfuric acid attack.

  11. [Latex exposure and gloves' use in health settings: old and new issues].

    PubMed

    Crippa, Michela

    2008-01-01

    The diffusion of the "universal precautions", promoted in 1987 by the Center for Disease Control and Prevention, dramatically increased the use of latex glove in health care settings for protection against the HIV and HBV. The increased demand caused an increased production of gloves, a reduction in processing time and a different chemical treatment of rubber trees which lowered the glove quality, that means high levels of antigens and high powder content. This situation caused an increase of frequency of allergic (type I and type IV) and irritant reactions to latex gloves in health care workers. Recommendations and guidelines for the prevention of latex allergy in health care settings were available from 1995 both in Italy and in other countries. When properly applied, the preventive effectiveness of these suggestions has been demonstrated, but unfortunately the guidelines are not widely adopted as we could think and the frequency of latex allergy and sensitization in health care workers is not as reduced as it could be expect. This could be due also to the fact that some practical issues are still open, for example: the possibility of assessing the real glove quality and the reliability of information provided by manufacturers that often are inaccurate and incomplete; the necessity to update the regulations in force to higher quality standards; the availability of procedures for the selection, purchase and use of gloves in relation to specific tasks within health care setting; the involvement of occupational physicians in the management of these procedures; clear indications of limit values for extractable latex allergens in medical and common latex devices; the assessment of the real protective efficacy against chemicals and biological agents of new synthetic rubber gloves. An Italian working group of occupational health professionals, involved for a long time in the management of glove and latex related problems in health care settings,finalized a consensus

  12. Development of a latex agglutination test with recombinant variant surface glycoprotein for serodiagnosis of surra.

    PubMed

    Rogé, S; Baelmans, R; Claes, F; Lejon, V; Guisez, Y; Jacquet, D; Büscher, P

    2014-10-15

    Serodiagnosis of surra is commonly performed with the CATT/Trypanosoma evansi direct agglutination test. This antibody detection test is based on lyophilised bloodstream form trypanosomes propagated in rats and presenting the predominant variant surface glycoprotein (VSG) RoTat 1.2 on their surface. Recently, the N-terminal fragment of VSG RoTat 1.2 has been expressed as a recombinant protein in the yeast Pichia pastoris and showed diagnostic potential in ELISA. This recombinant antigen has now been incorporated in a latex agglutination test, the rLATEX/T. evansi. In this study, we compared the diagnostic accuracy of rLATEX/T. evansi and CATT/T. evansi with immune trypanolysis (TL) as reference test on a total of 1717 sera from camels, horses, bovines, water buffaloes, dogs and sheep. The rLATEX/T. evansi displayed a slightly better agreement with TL than CATT/T. evansi (kappa [κ] respectively 0.84 and 0.72). The sensitivities of rLATEX/T. evansi (84.2%, 95% CI 80.8-87.1) and CATT/T. evansi (84.0%, 95% CI 80.6-87.0) were similar, but rLATEX/T. evansi was significantly more specific (97.7%, 95% CI 96.7-98.4) than CATT/T. evansi (89.4%; 95% CI 87.6-91.1). We consider the rLATEX/T. evansi an alternative for the CATT/T. evansi, with the advantage that the use of a purified recombinant antigen leads to a more standardised diagnostic test with an improved specificity. Moreover, it eliminates the use of laboratory animals and can be easily scaled-up, e.g. in biofermentors.

  13. Latex-allergic patients sensitized to the major allergen hevein and hevein-like domains of class I chitinases show no increased frequency of latex-associated plant food allergy

    PubMed Central

    Radauer, Christian; Adhami, Farzaneh; Fürtler, Irene; Wagner, Stefan; Allwardt, Dorothee; Scala, Enrico; Ebner, Christof; Hafner, Christine; Hemmer, Wolfgang; Mari, Adriano; Breiteneder, Heimo

    2011-01-01

    Allergies to certain fruits such as banana, avocado, chestnut and kiwi are described in 30–70% of latex-allergic patients. This association is attributed to the cross-reactivity between the major latex allergen hevein and hevein-like domains (HLDs) from fruit class I chitinases. We aimed to assess the extent of cross-reactivity between hevein and HLDs using sera from latex-allergic patients with and without plant food allergy. Hevein and HLDs of latex, banana, and avocado chitinases were expressed in Escherichia coli as fusion proteins with the maltose-binding protein and purified by affinity chromatography. IgE binding to these proteins was studied in sera from 59 latex-allergic patients and 20 banana-allergic patients without latex allergy by ELISA and ELISA inhibition. Additionally, 16,408 allergic patients’ sera were tested for IgE binding to hevein, latex chitinase, and wheat germ agglutinin using an allergen microarray. Hevein-specific IgE was detected in 34/59 (58%) latex-allergic patients’ sera. HLDs of latex, banana, and avocado chitinases were recognized by 21 (36%), 20 (34%), and 9 (15%) sera, respectively. In contrast, only one of 20 banana-allergic patients without latex allergy was sensitized to chitinase HLDs. In most tested latex-allergic patients’ sera, IgE binding to hevein was only partially reduced by preincubation with HLDs. Among hevein-sensitized, latex-allergic patients, the percentage of plant food allergy (15/34 = 44%) was equal to latex-allergic patients without hevein sensitization (11/25 = 44%). In the general allergic population, 230 of 16,408 sera (1.4%) reacted to hevein and/or a hevein-like allergen. Of these, 128 sera showed an isolated sensitization to hevein, whereas only 17 bound to latex chitinase or wheat germ agglutinin without hevein sensitization. In conclusion, the IgE response to HLDs is elicited by hevein as sensitizing allergen in most cases. Despite considerable cross-reactivity between these allergens, no

  14. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseny, Jonathan A.; Arp, Larry D.; Lindbergh, Charles

    1992-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar base subjected to 1-atm internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design (1) during construction, (2) under pressurization, and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the airtightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the Moon.

  15. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseney, Jonathan A.; Arp, Larry Dean; Lindbergh, Charles

    1989-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar based subjected to one atmosphere internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design: (1) during construction; (2) under pressurization; and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the air-tightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the moon.

  16. New hybrid latexes from a soybean oil-based waterborne polyurethane and acrylics via emulsion polymerization.

    PubMed

    Lu, Yongshang; Larock, Richard C

    2007-10-01

    A series of new waterborne polyurethane (PU)/acrylic hybrid latexes have been successfully synthesized by the emulsion polymerization of acrylic monomers (butyl acrylate and methyl methacrylate) in the presence of a soybean oil-based waterborne PU dispersion using potassium persulfate as an initiator. The waterborne PU dispersion has been synthesized by a polyaddition reaction of toluene 2,4-diisocyanate and a soybean oil-based polyol (SOL). The resulting hybrid latexes, containing 15-60 wt % SOL as a renewable resource, are very stable and exhibit uniform particle sizes of 125 +/- 20 nm as determined by transmittance electronic microscopy. The structure, thermal, and mechanical properties of the resulting hybrid latex films have been investigated by Fourier transform infrared spectroscopy, solid state 13C NMR spectroscopy, dynamic mechanical analysis, extraction, and mechanical testing. Grafting copolymerization of the acrylic monomers onto the PU network occurs during the emulsion polymerization, leading to a significant increase in the thermal and mechanical properties of the resulting hybrid latexes. This work provides a new way of utilizing renewable resources to prepare environmentally friendly hybrid latexes with high performance for coating applications. PMID:17877401

  17. Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.

    PubMed

    Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

    2015-02-01

    The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise in vitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

  18. [Coupling effects of water and chemical fertilizers on Hevea brasiliensis latex yield].

    PubMed

    Hua, Yuan-Gang; Chen, Qiu-Bo; Lin, Zhao-Mu; Luo, Wei

    2008-06-01

    Water and nutrient are the two main factors limiting Hevea brasiliensis growth and its latex yield. With 17 year-old Clone SCATC 7-33-97 H. brasiliensis as test material, the coupling effects of water and chemical N, P and K fertilizers on latex yield were studied by general orthogonal rotation design of quadratic regression with four factors and five levels under field condition, and a regressive mathematical model was set up based on the latex yield by quadratic regression analysis. The results showed that all test coupling levels of water and chemical fertilizers had significant effects on the latex yield. The yield-increasing effect of test factors was in the order of N application rate > irrigation amount > P application rate > K application rate, while the coupling effect of water and chemical fertilizers was in the sequence of water and N > N and P > water and P > water and K. There was a negative coupling effect of K application rate and soil moisture content. For latex yield, the optimum application rates of chemical fertilizers were 476.39 kg x hm(-2) of urea, 187.70 kg x hm(-2) of superphosphate and 225.77 kg x hm(-2) of potassium chloride, and the optimum irrigation amount was to have 82.78% soil relative water content. PMID:18808010

  19. Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.

    NASA Astrophysics Data System (ADS)

    Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

    2015-02-01

    The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise invitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

  20. Comparative analysis of Papaver somniferum genotypes having contrasting latex and alkaloid profiles.

    PubMed

    Chaturvedi, Nidarshana; Singh, Mridula; Shukla, Ashutosh K; Shasany, Ajit K; Shanker, Karuna; Lal, Raj K; Khanuja, Suman P S

    2014-07-01

    Papaver somniferum produces therapeutically useful benzylisoquinoline alkaloids (BIAs) like papaverine, thebaine, codeine, and morphine that accumulate in its capsular latex. Morphine is a potent analgesic but is also abused as a narcotic, which has increased the demand for non-narcotic thebaine that can be converted into various analgesics. To curtail the narcotic menace, many distinct genotypes of the plant have been developed that are deficient in morphine and/or latex. Sujata is one such latex-less low alkaloid-producing variety developed from the alkaloid-rich gum harvest variety Sampada. Its utility for gene prospecting and studying differential gene regulation responsible for its low alkaloid, nutritive seed oil, and latex-less phenotype has been exploited in this study. BIA profiling of Sujata and Sampada capsules at the early and late stages indicated that except for thebaine, Sujata had a depressed alkaloid phenotype as compared to Sampada. Comparative transcript-based analysis of the two genotypes was carried out in the early stage capsule (higher thebaine) using subtractive hybridization and microarray. Interrogation of a P. somniferum array yielded many differentially expressing transcripts. Their homology-based annotation classified them into categories--latex related, oil/lipid related, alkaloid related, cell wall related, and others. These leads will be useful to characterize the highly sought after Sujata phenotype.

  1. Incidence of sensitization, symptoms, and probable occupational rhinoconjunctivitis and asthma in apprentices starting exposure to latex.

    PubMed

    Archambault, S; Malo, J L; Infante-Rivard, C; Ghezzo, H; Gautrin, D

    2001-05-01

    Latex is a well-known sensitizer. Prospective studies in apprentices beginning to be exposed to latex have not been carried out. We wanted to determine the incidence of skin reactivity, cutaneous symptoms, rhinoconjunctivitis (RC) symptoms, respiratory symptoms, probable occupational RC, and asthma in apprentices in dental hygiene. A total of 122 students starting a program in dental hygiene technology were recruited between 1993 and 1995. A questionnaire, skin-prick tests with common aeroallergens and latex, and assessment of spirometry and responsiveness to methacholine were carried out on entry and at follow-up visits at 20 and 32 months after the start of exposure. Of the 110 subjects who participated for at least 1 follow-up visit, skin reactivity to latex developed in 7. Cutaneous symptoms developed in 6 of the 7, RC symptoms developed in 2, and respiratory symptoms developed in 1. Five of the 7 subjects had significant changes in methacholine responsiveness and fulfilled the definition of probable occupational asthma. Sensitized subjects were more likely to be atopic and to have a previous history of asthma and respiratory symptoms on exercise than were nonsensitized subjects. Three subjects at the 20-month assessment and 4 subjects at the 32-month visit showed skin reactivity. The cumulative incidences for skin sensitization, probable occupational RC, and occupational asthma to latex were 6.4%, 1.8%, and 4.5%, respectively. PMID:11344363

  2. Methods for ultimate load analysis of concrete containments: Second phase: Interim report

    SciTech Connect

    Dameron, R.A.; Dunham, R.S.; Rashid, Y.R.

    1987-03-01

    This summary report gives an overview of research on the influence of special effects on the ultimate load behavior of concrete containment structures. The special effects analyses that were performed include containment response under combined pressure and temperature, shear dislocation at a major concrete crack, wall discontinuity at the wall-basemat juncture, flawed liner, and thermal buckling. The EPRI-sponsored finite element code, ABAQUS-EPGEN, is utilized as the structural analysis tool in this research. The code was modified to incorporate a constitutive model for plain concrete and models for concrete/liner and concrete/rebar interaction. The report provides a general assessment of local effects mechanisms in concrete containment response to overpressurization.

  3. Concrete containment aging study

    SciTech Connect

    Pachner, J.; Tai, T.M.; Naus, D.

    1994-04-01

    In 1989, IAEA initiated a pilot study on the management of aging of nuclear power plant components. The Phase I and II studies of concrete containment are discussed. With the data base, plant owners will be able to review and enhance their existing programs. IAEA will analyze data provided by participating plants and the report is scheduled to be released by late 1994 (final report release mid-1995).

  4. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  5. Experimental and theoretical study of delayed ettringite damage in concrete

    NASA Astrophysics Data System (ADS)

    Ramadan, Elsaid Osman

    2000-12-01

    An experimental study is conducted to investigate the effect of a range of parameters on concrete expansion and premature deterioration associated with delayed ettringite formation (DEF). These parameters were identified from a comprehensive literature review; they include concrete curing conditions and cement chemistry. Specifically, the study investigated the effect of potassium and magnesium contents as well as the effect of water and steam curing conditions on concrete damage associated with DEF. An accelerated test method for DEF was evaluated and modifications are suggested. Concrete specimens were prepared with varying amounts of potassium and magnesium and subjected to different curing conditions. To accelerate any potential expansion, a beat cycle was employed. The change in length of the specimens was monitored for the duration of the study. Specimens were analyzed using the scanning electron microscope, x-ray dispersive analysis, and x-ray diffraction to determine the mechanism responsible for deterioration. Computed tomography x-ray was also employed as a non-destructive method for examining the internal crack patterns associated with expansion. The expansion data is fitted using the Kohnogorov-Avrami-Johenson-Mehl (KAJM) equation. This theory makes it possible to identify individual expansion processes and to identify the contribution of different expansion mechanisms. All concretes showed expansion following the beat cycle. Subjecting concrete to the heat cycle has a primary role in accelerating expansion. The age at which concrete is subjected to the beat cycle as well as the sample dimensions have a profound effect on the resulting expansion. The use of the concrete prisms as suggested in the modified test method offers a better alternative to cores suggested by Duggan. Increasing the potassium content has a deleterious effect on concrete expansion and premature deterioration and is also associated with dramatic reduction in compressive strength

  6. The prevalence of latex sensitisation and allergy and associated risk factors among healthcare workers using hypoallergenic latex gloves at King Edward VIII Hospital, KwaZulu-Natal South Africa: a cross-sectional study

    PubMed Central

    Phaswana, Shumani Makwarela; Naidoo, Saloshni

    2013-01-01

    Objectives The present study describes latex sensitisation and allergy prevalence and associated factors among healthcare workers using hypoallergenic latex gloves at King Edward VIII Hospital in KwaZulu-Natal, South Africa. Design Cross-sectional study. Setting A tertiary hospital in eThekwini municipality, KwaZulu-Natal, South Africa. Participants 600 healthcare workers were randomly selected and 501 (337 exposed and 164 unexposed) participated. Participants who were pregnant, with less than 1 year of work as a healthcare worker and a history of anaphylactic reaction were excluded from the study. Primary and secondary outcome measures Latex sensitisation and latex allergy were the outcome of interest and they were successfully measured. Results The prevalence of latex sensitisation and allergy was observed among exposed workers (7.1% and 5.9%) and unexposed workers (3.1% and 1.8%). Work-related allergy symptoms were significantly higher in exposed workers (40.9%, p<0.05). Duration of employment was inversely associated with latex allergy (OR 0.9; 95% CI 0.8 to 0.9). The risk of latex sensitisation (OR 4.2; 95% CI 1.2 to 14.1) and allergy (OR 5.1; 95% CI 1.2 to 21.2) increased with the exclusive use of powder-free latex gloves. A dose–response relationship was observed for powdered latex gloves (OR 1.1; 95% CI 1.0 to 1.2). Atopy (OR 1.5; 95% CI 0.7 to 3.3 and OR 1.4; 95% CI 0.6 to 3.2) and fruit allergy (OR 2.3; 95% CI 0.8 to 6.7 and OR 3.1; 95% CI 1.1 to 9.2) also increased the risk of latex sensitisation and allergy. Conclusions This study adds to previous findings that healthcare workers exposed to hypoallergenic latex gloves are at risk for developing latex sensitisation highlighting its importance as an occupational hazard in healthcare. More research is needed to identify the most cost effective way of implementing a latex-free environment in resource-limited countries, such as South Africa. In addition more cohort analysis is required to better

  7. Chlorine signal attenuation in concrete.

    PubMed

    Naqvi, A A; Maslehuddin, M; ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method.

  8. Characterization of a mouse model of allergy to a major occupational latex glove allergen Hev b 5.

    PubMed

    Hardy, Charles L; Kenins, Linda; Drew, Alexander C; Rolland, Jennifer M; O'Hehir, Robyn E

    2003-05-15

    Allergen-specific immunotherapy is a clinically proven effective treatment for many allergic diseases, including asthma; however, it is not currently available for latex allergy because of the high risk of anaphylaxis. There is, therefore, a crucial need for an animal model of latex allergy in which to develop effective immunotherapy. Previous mouse models of latex allergy either did not characterize the allergic pulmonary immune response or used crude latex extracts, making it difficult to quantify the contribution of individual proteins and limiting their usefulness for developing specific immunotherapy. We immunized mice with recombinant Hev b 5, a defined major latex allergen, or latex glove protein extract, representing the range of occupationally encountered processed latex allergens. The immune response was compared with that seen in ovalbumin-immunized mice. Immunization with Hev b 5 or glove extract elicits hallmarks of allergic pulmonary Th2-type immune responses, comparable to those for ovalbumin, including (1) serum antigen-specific IgE, (2) an eosinophilic inflammatory infiltrate in the lung, (3) increased interleukin-5 in lung bronchoalveolar lavage fluid, and (4) mucus hypersecretion by epithelial cells in the lung airways. This mouse model will aid the development of potentially curative treatments for latex-sensitized individuals, including those with occupational asthma.

  9. Industrial-hygiene walk-through survey report of Firestone Synthetic Rubber and Latex Company, Lake Charles, Louisiana

    SciTech Connect

    Fajen, J.M.; Ungers, L.J.

    1986-03-01

    A walk-through survey was conducted at the Firestone Synthetic Rubber and Latex Company, Lake Charles, Louisiana in July, 1985. The purpose of the survey was to obtain information on the 1,3-butadiene polymer manufacturing process and evaluate exposure potential. Bulk samples of vinylpyridine latex, styrene/butadiene rubber, and polybutadiene rubber were analyzed for residual 1,3-butadiene.

  10. Preparation and Characterization of Latex Particles as Potential Physical Shale Stabilizer in Water-Based Drilling Fluids

    PubMed Central

    Liu, Junyi; Qiu, Zhengsong; Huang, Wei'an; Song, Dingding; Bao, Dan

    2014-01-01

    The poly(styrene-methyl methacrylate) latex particles as potential physical shale stabilizer were successfully synthesized with potassium persulfate as an initiator in isopropanol-water medium. The synthesized latex particles were characterized by Fourier transform infrared spectroscopy (FT-IR), particle size distribution measurement (PSD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). FT-IR and TGA analysis confirmed that the latex particles were prepared by polymerization of styrene and methyl methacrylate and maintained good thermal stability. TEM and PSD analysis indicated that the spherical latex particles possessed unimodal distribution from 80 nm to 345 nm with the D90 value of 276 nm. The factors influencing particle size distribution (PSD) of latex particles were also discussed in detail. The interaction between latex particles and natural shale cores was investigated quantitatively via pore pressure transmission tests. The results indicated that the latex particles as potential physical shale stabilizer could be deformable to bridge and seal the nanopores and microfractures of shale to reduce the shale permeability and prevent pore pressure transmission. What is more, the latex particles as potential physical shale stabilizer work synergistically with chemical shale stabilizer to impart superior shale stability. PMID:25302336

  11. Discontinuation of Living Donor Liver Transplantation due to Donor's Intraoperative Latex-Induced Anaphylactic Shock

    PubMed Central

    Shinoda, Masahiro; Tanabe, Minoru; Nagao, Keisuke; Kitago, Minoru; Fujisaki, Hiroto; Odaira, Masanori; Kawachi, Shigeyuki; Itano, Osamu; Obara, Hideaki; Matsubara, Kentaro; Shimojima, Naoki; Fuchimoto, Yasushi; Hoshino, Ken; Amagai, Masayuki; Kuroda, Tatsuo; Kitagawa, Yuko

    2012-01-01

    We report on a 33-year-old female liver donor candidate who developed intraoperative latex-induced anaphylactic shock during surgery for living donor transplantation. She was the mother of the organ recipient, who was a 9-year-old boy with biliary atresia. We planned extended lateral segmentectomy for her. Although we dissected the ligament around the left lobe, the systolic blood pressure suddenly dropped and her body became flushed and warm. We administered transfusion and an ephedrine injection to recover the blood pressure. Because she recovered after the treatment, we restarted the procedure. However, she went into shock again within a few minutes. We decided to discontinue the operation. Postoperative blood tests revealed an increase in IgE-RAST and basophil activation, suggesting that the anaphylactic shock was induced by latex. Because latex allergy has become a public health problem, this allergy should be kept in mind as a potential donor operation risk. PMID:23294079

  12. Latex Paint-gun Injuries of the Hand: Are the Outcomes Better?

    PubMed Central

    Lozano-Calderón, Santiago A.; Mudgal, Sharmila; Ring, David

    2008-01-01

    This study aims to present the functional outcome in patients who sustained paint-gun injuries to the hand with latex paint and review the current trends, recommendations, and pitfalls of surgical treatment in contemporary literature. Five male patients with an average age of 35 years were treated between 2000 and 2003 after sustaining a paint-gun injury with latex paint. All wounds were located volarly on the digits of the nondominant hand. Preoperative radiographs were obtained in every patient. All patients underwent debridement of the affected digit. Despite delayed presentation, more than 24 h post injury, our patients recovered substantial function at an average follow-up of 12 months. Every patient returned to his previous occupation and there were no amputations. Paint-gun injuries with latex paint appear to be associated with an outcome that is superior to the poor outcome traditionally associated with oil-based paints. PMID:18780017

  13. Comparative study of electrophoretic patterns of latex proteins from clones of Hevea brasiliensis.

    PubMed

    Arreguín, B; Lara, P; Rodríguez, R

    1988-07-01

    Latex serum proteins from Hevea brasiliensis were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Proteins from whole serum and fractions isolated by gel chromatography on Ultrogel AcA 44 were analyzed. No qualitative clonal differences were found in the protein patterns of whole latex or in the fractions but laser densitometry revealed reliable quantitative differences in protein composition. Reproducible mobilities and molecular weights of selected bands were obtained both within single gels as well as in different gels, analyzing several lots of latex received at various times from a Hevea experimental field station. The clones compared were IAN 710, GV 31, GV 42; the first one had the highest rubber yields. PMID:3234370

  14. Resonance energy transfer from dibucaine to acriflavine in polystyrene latex dispersions.

    PubMed

    Li, Yuan; Kuwabara, Hiroe; Gong, Yong-Kuan; Takaki, Yuki; Nakashima, Kenichi

    2003-07-01

    Resonance energy transfer from dibucaine (DC) to acriflavine (AF) has been investigated both in homogeneous aqueous solutions and in polystyrene latex dispersions. The energy transfer reaction is observed by monitoring fluorescence quenching of DC as well as sensitized emission of AF. It is found that the energy transfer from DC to AF is remarkably enhanced on going from the aqueous homogeneous solution to the latex dispersion. This is mainly attributed to the fact that both the donor and acceptor are effectively adsorbed onto the latex particles, as evidenced by the measurement of adsorption isotherms. From the adsorption experiments, it is also elucidated that electrostatic interaction is significant at low DC concentration, while hydrophobic interaction dominates at the higher concentration especially at higher pH.

  15. Simulation of Latex Film Formation Using a Cell Model in Real Space: Vertical Drying.

    PubMed

    Gromer, A; Nassar, M; Thalmann, F; Hébraud, P; Holl, Y

    2015-10-13

    This paper presents a simulation tool applied to latex film formation by drying, a hybrid between a classical numerical resolution method using finite differences and cellular automata, and making use of object-oriented programming. It consists of dividing real space into cells and applying local physical laws to simulate the exchange of matter between neighboring cells. In a first step, the simulation was applied to the simple case of vertical drying of a latex containing only one population of monodisperse particles and water. Our results show how the distribution of latex particles evolves through the different drying stages due to a combination of diffusion, convection, and particle deformation. While repulsive interactions between the particles tend to favor homogeneous distributions in the first drying stage, concentration gradients that develop in opposite ways can be observed depending on the drying regime. The distributions, calculated in various cases, reproduce and extend several theoretical results and are in qualitative agreement with some experimental findings. PMID:26378376

  16. High density monolayers of plasmid protein on latex particles: experiments and theoretical modeling

    NASA Astrophysics Data System (ADS)

    Kujda, Marta; Adamczyk, Zbigniew; Cieśla, Michał; Adamczyk, Małgorzata

    2015-04-01

    Monolayers obtained by adsorption of the plasmid protein KfrA on negatively charged polystyrene latex particles under diffusion-controlled conditions at pH 3.5 were interpreted in terms of the random sequential adsorption (RSA) model. A quantitative agreement of the theoretical results derived from these calculations with experimental data was attained for the ionic strength from 0.15 up to 10-2 M. This confirmed the adsorption mechanism of KfrA molecules on latex in the form of tetramers up to 10-2 M. On the other hand, for the ionic strength of 10-3 M the experimental coverage agreed with theoretical predictions under the assumption that screening of electrostatic interaction is enhanced by the presence of counterions and negatively charged polymer chains stemming from latex particles.

  17. Latex laboratory-gloves: an unexpected pitfall in amphibian toxicity assays with tadpoles.

    PubMed

    Gutleb, A C; Bronkhorst, M; van den Berg, J H; Murk, A J

    2001-07-01

    This study examined the unexpected toxic effects of protective latex laboratory gloves on developing amphibians. Mortality after exposure to rinsing water from the outside of the gloves was observed in Xenopus laevis and Rana temporaria, with R. temporaria being more sensitive. This phenomenon was further confirmed using the microtiter-version of the Microtox-Assay, an in vitro assay for general toxicity. Latex gloves from the specific brand used in the experiment, in which the toxicity to tadpoles was observed for the first time, showed the highest toxicity of all materials and brands tested. Due to the high responsiveness of amphibian tadpoles to latex-glove contaminated rinsing water, special care is necessary when cleaning aquaria during toxicological experiments with amphibians as otherwise results may be biased.

  18. Optimization of reinforced concrete slabs

    NASA Technical Reports Server (NTRS)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  19. Electrical conductivity as a test for the integrity of latex gloves

    SciTech Connect

    Stampfer, J.F.; Kissane, R.J.; Schauer, S.M.

    1993-02-01

    Surgical latex gloves have been used to protect patients against bacterial infections introduced by health-care workers. As a result of the Acquired Immune Deficiency Syndrome (AIDS) epidemic, the concern has shifted, with more emphasis on the protection of the health-care worker from the patient. These gloves often have defects, holes, which allow bacteria to penetrate. There are a number of methods to test the integrity of these gloves before they are donned. The present standard test is to fill the glove with 1000 ml of water and visually inspect the exterior for water leaks. Another method allows the gloves to be tested while being worn. This is done by measuring the electrical conductivity through the latex, from the hand to an external conductive solution. We have investigated the use of electrical conductivity to test sterile latex gloves, both with and without holes. We have studied various phenomena associated with this testing and conducted simultaneous electrical and viral penetration tests. Our conclusions are as follows. (1) Electrical conductivity test method for gloves while they are being worn is very dependent on the specific glove being tested, primarily on the conductivity of the intact glove. (2) In the best of cases, reliable results could be expected for only about one hour of wear and for holes larger than 10s of [mu]ms. (3) There are practical problems that may disqualify the electrical conductivity test for routine use. (4) The test may prove to be valuable as a QA test procedure for nonconductive materials and garments made from these materials because it has greater sensitivity than presently used methods. (5) The effective sizes of holes in latex increase much faster when the latex is stretched than would be predicted from the elongation of the latex.

  20. Electrical conductivity as a test for the integrity of latex gloves

    SciTech Connect

    Stampfer, J.F.; Kissane, R.J.; Schauer, S.M.

    1993-02-01

    Surgical latex gloves have been used to protect patients against bacterial infections introduced by health-care workers. As a result of the Acquired Immune Deficiency Syndrome (AIDS) epidemic, the concern has shifted, with more emphasis on the protection of the health-care worker from the patient. These gloves often have defects, holes, which allow bacteria to penetrate. There are a number of methods to test the integrity of these gloves before they are donned. The present standard test is to fill the glove with 1000 ml of water and visually inspect the exterior for water leaks. Another method allows the gloves to be tested while being worn. This is done by measuring the electrical conductivity through the latex, from the hand to an external conductive solution. We have investigated the use of electrical conductivity to test sterile latex gloves, both with and without holes. We have studied various phenomena associated with this testing and conducted simultaneous electrical and viral penetration tests. Our conclusions are as follows. (1) Electrical conductivity test method for gloves while they are being worn is very dependent on the specific glove being tested, primarily on the conductivity of the intact glove. (2) In the best of cases, reliable results could be expected for only about one hour of wear and for holes larger than 10s of {mu}ms. (3) There are practical problems that may disqualify the electrical conductivity test for routine use. (4) The test may prove to be valuable as a QA test procedure for nonconductive materials and garments made from these materials because it has greater sensitivity than presently used methods. (5) The effective sizes of holes in latex increase much faster when the latex is stretched than would be predicted from the elongation of the latex.

  1. Radio-frequency drying of latex adhesive on carpet. Final report

    SciTech Connect

    Carr, W.W.

    1993-08-01

    Approximately half of the world`s carpet production is in the United States. During the tufting of carpet, face yarns are inserted through the primary backing, but are not locked in. Secondary lamination with a latex adhesive (backcoating) anchors the tufts, adheres to the secondary backing and provides dimensional stability. Unbacked carpet is pulled through an applicator that applies a layer of latex adhesive to the back side of the carpet. The coated carpet is then laminated to the secondary backing (which has a thin layer adhesive applied to it) and transported by a tenter frame through a convection oven for drying and curing the latex adhesive. Laboratory drying tests were conducted with convection and rf ovens to simulate production conditions and provide a baseline for evaluating the effects of rf heating on drying and curing two typical qualities of carpet (23 and 32 oz/sq yd). With rf preheating the latex temperature increased to 100{degrees}C in less than 20 seconds while it took more than 300 seconds for convective heating. Rf preheating was also found to significantly increase the subsequent drying rate in the convection oven. Since the convective drying rate does not appreciably decrease until the target moisture content of 5% is reached and benefits of preheating are lost when the rf oven follows the convection oven, rf postheating does not offer the advantages of rf preheating. Conclusions are: (1) The component primarily responsible for rf heating of latex-backed carpet is water. (2) Rf preheating and rf postheating are technically feasible. Both reduce moisture content in latex-backed carpet without affecting product quality. (3) Rf preheating has more potential than rf postheating since it eliminates the heating time to reach the maximum drying rate associated with convective drying. (4) Retrofitting an existing backcoating line with a 330-kW rf preheating oven could increase production from 50 fpm to 100 fpm with a simple payback of 1.4 years.

  2. Clay/latex mixture stops lost circulation in large carbonate fractures

    SciTech Connect

    Kurochkin, B.

    1995-08-28

    A mixture of latex and drilling mud clay controls lost circulation in large carbonate fractures by coagulating when it mixes with the formation fluids. The mixture forms large aggregates capable of plugging large formation fractures and is not prone to being washed out by formation water. The Scientific Research Institute of Drilling Techniques in Moscow (Vniibt) has developed a special lost circulation mixture combining a latex base and clay drilling mud for use in plugging these fractures. Mud powders of bentonite and calcium clays can be used to prepare the clay-latex mixture (GPC). The latex is mixed with drilling mud made from bentonite clay powder and is pumped to the lost circulation zone where it coagulates by reacting with the calcium ions in the formation water. The latex used to prepare GPC must be compatible with the mud being used. After coagulation, GPC changes to a rubber mixture. In the Tataria oil region, one of the drilling enterprises used GPC in 23 wells, with positive results in 20 of the wells. The bentonite powder base GPC mixture remains easily pumpable until the end of the operation. The mixture`s plastic strength increases over time as it is pumped into the lost circulation zone. This type of mixture is typically used to control lost circulation at depths greater than 1,000--1,500 m. GPC based on drilling mud made from calcium clay is used at shallower depths. For GPC pumped into a borehole, the latex/clay drilling mud ratio is typically between 1:1 and 1:2.

  3. Prolong the life of concrete

    SciTech Connect

    Ilaria, J.E.

    1995-07-01

    The most widely used construction materials are concrete and related cement-based products, such as common building block. The excellent reputation of concrete as a durable material of construction has been questioned i modern times. The expanded use of Portland cement concrete, the increase in corrosive environments, and lack of understanding of the composition of concrete all indicate a need for methods to increase life expectancy. Chemical and mechanical factors can shorten service life. Understanding these properties will lead to the proper application of protective coatings.

  4. Microwave NDE for Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Arunachalam, Kavitha; Melapudi, Vikram R.; Rothwell, Edward J.; Udpa, Lalita; Udpa, Satish S.

    2006-03-01

    Nondestructive assessment of the integrity of civil structures is of paramount importance for ensuring safety. In concrete imaging, radiography, ground penetrating radar and infrared thermography are some of the widely used techniques for health monitoring. Other emerging technologies that are gaining impetus for detecting and locating flaws in steel reinforcement bar include radioactive computed tomography, microwave holography, microwave and acoustic tomography. Of all the emerging techniques, microwave NDT is a promising imaging modality largely due to their ability to penetrate thick concrete structures, contrast between steel rebar and concrete and their non-radioactive nature. This paper investigates the feasibility of a far field microwave NDE technique for reinforced concrete structures.

  5. Expression and activity of cell-wall-degrading enzymes in the latex of opium poppy, Papaver somniferum L.

    PubMed

    Pilatzke-Wunderlich, I; Nessler, C L

    2001-03-01

    The alkaloid-rich latex of the opium poppy, Papaver somniferum L., is valued as a source of pharmaceuticals including thebaine, codeine, and morphine, but is also harvested for heroin production. The poppy laticifer system develops through the gradual disappearance of the common walls between differentiating laticifer elements throughout the plant. Gene homologues for cell-wall-degrading enzymes were found during random sequencing of an opium poppy latex cDNA library. RNA gel blot analysis of cellulase, polygalacturonase beta-subunit, 1,3-beta-glucanase, and xyloglucan endotransglycosylase homologues showed their expression was not limited to laticifers. In contrast, poppy gene homologues to pectin methylesterase (PME), pectin acetylesterase (PAE) and pectate lyase (PL) where all highly expressed and latex-specific. Enzyme assays confirmed the presence of PME, PAE, and PL activities in latex serum. The abundance of transcripts encoding pectin-degrading enzymes in latex suggests that these enzymes may play an important role in laticifer development.

  6. Mechanical and morphological properties of kenaf powder filled natural rubber latex foam

    SciTech Connect

    Karim, Ahmad Fikri Abdul Ariff, Zulkifli Mohamad; Ismail, Hanafi

    2015-07-22

    This research is carried out by incorporate kenaf powder with natural rubber latex (NRL) compound and is foamed to make natural rubber latex foam (NRLF) by using a well known technique called Dunlop method. Different loading of kenaf powder was added to NRL compound and was foamed to make NRLF. The tensile properties, and morphology of kenaf filled NRLF was studied. Increase in kenaf loading reduced the tensile strength and elongation at break and of a compound. Modulus at 100% elongation of the compound increased with increased in filler loading. The morphological and micro structural characterization has been performed by using scanning electron microscopy (SEM)

  7. [The use of melamine-formaldehyde latex in the automated analysis of immunocompetent cells].

    PubMed

    Ovcharova, E N; Denisov, L A; Sukhomudrenko, A G

    1991-01-01

    The optimization of the loading of monodispersed melamine-formaldehyde latex with fluorochrome has permitted its use as indicator material, equally suitable both for the visual evaluation of the reaction of phagocytosis and for the automated evaluation of this reaction by means of a scanning fluorescent microscope. The study has shown the possibility of using fluorescent melamine formaldehyde latex for the evaluation of the phagocytosis of mouse peritoneal macrophages and human blood cells, as well as the analysis of the surface receptors of immunocompetent cells.

  8. Characterization of steel fiber and/or polymer concrete mixes and applications to slender rectangular and I-beams

    NASA Astrophysics Data System (ADS)

    Ahmed, Ashraf Ibrahim

    This dissertation presents results from experimental studies related to polymer modified concrete, steel fiber reinforced concrete, and steel fiber/polymer modified concrete. As a first stage of this research, the properties of different concrete mixes were characterized. These mixes were: plain concrete, steel fiber concrete with fiber volume fraction of 1%, polymer modified concrete with 1% to 7.5% solids of polymer, and steel fiber/polymer modified concrete with 1% to 7.5% polymer solids and I% steel fiber fraction. Concrete cylinders and 4 x 4 inches beams were tested under compressive, tensile, flexural, and bar pull-out loadings. In the second phase of this research, slender beams with a depth to width ratio of three were tested under four point loading for shear and flexure. Half I-beams, with gross aspect ratio of four and web aspect ratio of three were tested under the combined loading of bending, shear, and torsion. Lateral eccentric loads were applied transversely in the shallow direction to the 3 x 9 inches beams and the half I-beams. Dog bone shaped reinforced and un-reinforced specimens with 3 x 3 inches square sections were tested under pure torsional loading. The addition of 1% steel fibers alone or with 5% solids of polymers to concrete mixes improved their toughness and ductility. The contribution of steel fibers to bending, shear, and torsion in slender and half I-beams is presented. The ACI code methods for calculating the torsional, shear, and flexural resistance of beams are compared to the experimental results. Post crack analysis performed on the slender beams and half I-beams indicated that the tested specimens could carry 70% of the maximum applied loads after initial concrete cracking and failure. The reduction in the tensile stresses of stirrups and longitudinal reinforcing bars, due to the steel fibers and polymer, are presented. Fibers and polymers increase bending and toughness in concrete.

  9. Concrete Mixing Methods and Concrete Mixers: State of the Art.

    PubMed

    Ferraris, C F

    2001-01-01

    As for all materials, the performance of concrete is determined by its microstructure. Its microstructure is determined by its composition, its curing conditions, and also by the mixing method and mixer conditions used to process the concrete. This paper gives an overview of the various types of mixing methods and concrete mixers commercially available used by the concrete industry. There are two main types of mixers used: batch mixers and continuous mixers. Batch mixers are the most common. To determine the mixing method best suited for a specific application, factors to be considered include: location of the construction site (distance from the batching plant), the amount of concrete needed, the construction schedule (volume of concrete needed per hour), and the cost. Ultimately, the quality of the concrete produced determines its performance after placement. An important measure of the quality is the homogeneity of the material after mixing. This paper will review mixing methods in regards to the quality of the concrete produced. Some procedures used to determine the effectiveness of the mixing will be examined.

  10. Concrete Mixing Methods and Concrete Mixers: State of the Art

    PubMed Central

    Ferraris, Chiara F.

    2001-01-01

    As for all materials, the performance of concrete is determined by its microstructure. Its microstructure is determined by its composition, its curing conditions, and also by the mixing method and mixer conditions used to process the concrete. This paper gives an overview of the various types of mixing methods and concrete mixers commercially available used by the concrete industry. There are two main types of mixers used: batch mixers and continuous mixers. Batch mixers are the most common. To determine the mixing method best suited for a specific application, factors to be considered include: location of the construction site (distance from the batching plant), the amount of concrete needed, the construction schedule (volume of concrete needed per hour), and the cost. Ultimately, the quality of the concrete produced determines its performance after placement. An important measure of the quality is the homogeneity of the material after mixing. This paper will review mixing methods in regards to the quality of the concrete produced. Some procedures used to determine the effectiveness of the mixing will be examined. PMID:27500029

  11. Corrosion control of steel-reinforced concrete

    NASA Astrophysics Data System (ADS)

    Chung, D. D. L.

    2000-10-01

    The methods and materials for corrosion control of steel-reinforced concrete are reviewed. The methods are steel surface treatment, the use of admixtures in concrete, surface coating on concrete, and cathodic protection.

  12. Microbiological sampling of the atmosphere using a latex sounding balloon

    NASA Astrophysics Data System (ADS)

    Adkins, W. P.; Bryan, N.; Christner, B. C.; Guzik, T. G.; Stewart, M. F.; Giammanco, J. R.

    2010-12-01

    The occurrence of microbes in the atmosphere has been the subject of scientific inquiry since Louis Pasteur’s time; however, data on the nature and diversity of microbial life in the upper troposphere and stratosphere is very limited. To experimentally address this, we have designed, constructed, and field-tested a lightweight, autonomous system that can sample at high altitudes using a latex sounding balloon. An important aspect of our sampling protocol is the ability to decontaminate and assess the level of background contamination during laboratory and field handling. Our approach involves the parallel decontamination and monitoring of 3 identical payloads: (i) one that remains in the laboratory, (ii) a control on the flight string, and (iii) a payload that opens and samples airborne particles in the atmosphere. Comparative analysis of various sterilization methods indicated that ethylene oxide was most effective at decreasing the concentration of DNA-containing cells, decreasing background cellular contamination by 94%. In conjunction, germicidal ultraviolet light, sodium hypochlorite, and 70% ethanol were used to decrease the concentration of microbes associated with payload surfaces. Bioaerosol collection is achieved by impact sampling on a 3.5 mm^2 retention surface covered with a thin layer of sterile silicone grease as the payload travels through the atmosphere. Initial flights have been successful in recovering viable microorganisms present in parcels of air at altitudes of 3 km to 9 km. Microscopic analysis on the collected cell assemblages implied that ~70% of the cells were potentially viable, and aerobic heterotrophic bacteria were cultured and isolated from liquid and agar-solidified culture media. Future plans include increasing the sampling altitude up to ~30 km in a series of discrete steps, maintaining our background controls and connection to lower altitude measurements. The pressure, temperature, and radiation levels in Earth’s stratosphere

  13. Biodecontamination of radionuclide contaminated concrete

    SciTech Connect

    Hamilton, M.A.; Rogers, R.D.; Benson, J.

    1996-10-01

    Within the nuclear industry, there are literally hundreds of square miles of radionuclide contaminated concrete surfaces. A novel technology for biologically decontaminating concrete is being developed. The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of the concrete. Accelerated testing in laboratory conditions was conducted. The bacteria Thiobacillus thiooxidans, supplied from a continuous flow bioreactor, was applied to an exposed concrete surface. A control chamber exposing concrete to sterile media was operated under the same conditions. One hundred percent of surrogate cobalt contamination was recovered from the Thiobacillus treated concrete and 1 mm thickness of concrete material was removed in 60 days. Prototype chambers that can be mounted directly to concrete surfaces have been designed to allow control of environmental conditions to promote MID after inoculation of the surface with bacteria. Studies to determine optimum source and quantity of reduced sulfur, bacterial species or consortia best suited for rapid MID, and methods of application and delivery of bacteria and nutrients will be discussed.

  14. Concrete Masonry Designs: Educational Issue.

    ERIC Educational Resources Information Center

    Hertzberg, Randi, Ed.

    2001-01-01

    This special journal issue addresses concrete masonry in educational facilities construction. The issue's feature articles are: (1) "It Takes a Village To Construct a Massachusetts Middle School," describing a middle school constructed almost entirely of concrete masonry and modeled after a typical small New England village; (2) "Lessons Learned,"…

  15. The Concrete and Pavement Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  16. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  17. Technology Solutions Case Study: Insulating Concrete Forms

    SciTech Connect

    none,

    2012-10-01

    This Pacific Northwest National Laboratory project investigated insulating concrete forms—rigid foam, hollow walls that are filled with concrete for highly insulated, hurricane-resistant construction.

  18. Insights on the Phytochemical Profile (Cyclopeptides) and Biological Activities of Calotropis procera Latex Organic Fractions

    PubMed Central

    Jucá, Thiago Lustosa; Ramos, Márcio Viana; Moreno, Frederico Bruno Mendes Batista; Viana de Matos, Mayara Patrícia; Marinho-Filho, José Delano Barreto; Moreira, Renato Azevedo; Monteiro-Moreira, Ana Cristina de Oliveira

    2013-01-01

    Calotropis procera is a medicinal plant whose pharmacological properties are associated with its latex. Here, the Calotropis procera latex fractions were investigated in an attempt to trace its phytochemical profile and measure its anti-inflammatory and toxicity activity. The crude latex was partitioned, yielding five fractions (49.4% hexane, 5.2% dichloromethane, 2.0% ethyl acetate, 2.1% n-butanol, and 41.1% aqueous). Phytochemical screening and spectroscopy analysis revealed that dichloromethane is the most chemically diverse fraction. Triterpenes were detected in both the hexane and dichloromethane fractions, while flavonoids were detected in the dichloromethane and ethyl acetate fractions. These fractions were cytotoxic to cancer cell lines (LD50 0.05 to 3.9 μg/mL) and lethal to brine shrimp (LD50 10.9 to 65.7 μg/mL). Reduced neutrophil migration in rats was observed in carrageenan-induced peritonitis for the dichloromethane (67%), ethyl acetate (56%), and aqueous (72%) fractions. A positive reaction with tolidine and ninhydrin suggested that cyclopeptides are in the ethyl acetate fraction. It is therefore concluded that Calotropis procera latex dichloromethane and ethyl acetate fractions exhibit both in vitro and in vivo activities as well as anti-inflammatory properties. Cyclopeptide detection is especially interesting because previous attempts to investigate these low-molecular cyclic amino acid sequences in C. procera have failed. PMID:24348174

  19. Genotoxic potential of the latex from cotton-leaf physicnut (Jatropha gossypiifolia L.).

    PubMed

    de Almeida, Pedro Marcos; de Sousa Araújo, Silvany; Marin-Morales, Maria Aparecida; Benko-Iseppon, Ana Maria; Brasileiro-Vidal, Ana Christina

    2015-03-01

    Jatropha gossypiifolia L. (Euphorbiaceae), popularly known as cotton-leaf physicnut, is a milky shrub notable for its medicinal properties. The present study aimed to evaluate the toxic, cytotoxic and genotoxic effects of the latex of J. gossypiifolia, using Allium cepa L. as test system. Seeds of A. cepa were exposed to five concentrations of the latex (1.25; 2.5; 5; 10 and 20 mL/L) in order to evaluate parameters of toxicity (evaluation of root growth), cytotoxicity (mitotic index frequency) and genotoxicity (frequency of chromosome alterations). The latex showed a significant decrease in root mean growth value as well as mitotic index for the tested concentrations, except for 1.25 mL/L, when compared to results from the negative control. The 1.25, 2.5 and 5 mL/L concentrations induced significant chromo-some adherences, C-metaphases and/or chromosome bridges, as genotoxic effects. The significant frequency of chromosome bridges also indicated mutagenic potential for chromosomes of J. gossypiifolia as discussed in the paper. Considering that the latex is used in popular therapies, and that the test system A. cepa presents good correlation with tests carried out in mammals, it can be pointed out that its use for medicinal purposes may be harmful to human health especially if ingested. PMID:25983630

  20. Cross-reactivity in Cryptococcus antigen latex agglutination test in two commercial kits.

    PubMed

    Tone, Kazuya; Umeda, Yoshiko; Makimura, Koichi

    2016-05-01

    This article presents an examination of the cross-reactivity of pathogenic fungi with Cryptococcus neoformans in two commercial Cryptococcus antigen latex agglutination tests performed across 39 fungal strains. Some fungi were newly indicated as Cryptococcus cross-reactive, and the two kits showed differences in cross-reactive fungi. PMID:26922300

  1. The Condom Conundrum: Apply Peer Pressure, Not Latex, against Casual Sex.

    ERIC Educational Resources Information Center

    Delattre, Edwin J.

    1992-01-01

    If saving lives were our only moral concern, distributing condoms in schools is not the best way to proceed. Abstinence has greater life-saving power than any piece of latex. School condom distribution promotes casual, promiscuous sex, ignores this contraceptive's failure rate, and runs counter to sound educational policy. Deferred gratification…

  2. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Applicability; description of the latex foam subcategory. 428.110 Section 428.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT...

  3. Harvest height and frequency effects on guayule latex, rubbers, and resin yields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. The commercialization of guayule for hypoallergenic latex and other products such as resin for termite resistant wood products and as an energy source have renewed interest in production practices such as harv...

  4. Plant Population, Planting Date, and Germplasm Effects on Guayule Latex, Rubber and Resin Yields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. While guayule traditionally has been grown for rubber, more recently it is being grown for its hypoallergenic latex. Other uses such as termite resistant wood products and as an energy source have also been id...

  5. Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.

    PubMed

    Moradi, Mohammad-Amin; Larrakoetxea Angoitia, Katalin; van Berkel, Stefan; Gnanasekaran, Karthikeyan; Friedrich, Heiner; Heuts, Johan P A; van der Schoot, Paul; van Herk, Alex M

    2015-11-10

    We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it. PMID:26491888

  6. Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.

    PubMed

    Moradi, Mohammad-Amin; Larrakoetxea Angoitia, Katalin; van Berkel, Stefan; Gnanasekaran, Karthikeyan; Friedrich, Heiner; Heuts, Johan P A; van der Schoot, Paul; van Herk, Alex M

    2015-11-10

    We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it.

  7. Molten salt pyrolysis of latex. [synthetic hydrocarbon fuel production using the Guayule shrub

    NASA Technical Reports Server (NTRS)

    Bauman, A. J. (Inventor)

    1981-01-01

    Latex-rich plants such as Guayule or extracts thereof are pyrolyzed in an inert nitrogen atmosphere inorganic salt melts such as a LiCl/KCl eutectic at a temperature of about 500 C. The yield is over 60% of a highly aromatic, combustible hydrocarbon oil suitable for use as a synthetic liquid fuel.

  8. Response characteristics of esophageal balloon catheters handmade using latex and nonlatex materials

    PubMed Central

    Cross, Troy J; Lalande, Sophie; Hyatt, Robert E; Johnson, Bruce D

    2015-01-01

    The measurement of esophageal pressure allows for the calculation of several important and clinically useful parameters of respiratory mechanics. Esophageal pressure is often measured with balloon-tipped catheters. These catheters may be handmade from natural latex condoms and polyethylene tubing. Given the potential of natural latex to cause allergic reaction, it is important to determine whether esophageal catheter balloons can be fabricated, by hand, using nonlatex condoms as construction materials. To determine the static and dynamic response characteristics of esophageal balloon catheters handmade from latex and nonlatex materials, six esophageal catheter balloons were constructed from each of the following condom materials: natural latex, synthetic polyisoprene, and polyurethane (18 total). Static compliance and working volume range of each balloon catheter was obtained from their pressure-volume characteristics in water. The dynamic response of balloon catheters were measured via a pressure “step” test, from which a third-order underdamped transfer function was modeled. The dynamic ranges of balloon catheters were characterized by the frequencies corresponding to ±5% amplitude- and phase-distortion (fA5% and fφ5%). Balloon catheters handmade from polyurethane condoms displayed the smallest working volume range and lowest static balloon compliance. Despite this lower compliance, fA5% and fφ5% were remarkably similar between all balloon materials. Our findings suggest that polyisoprene condoms are an ideal nonlatex construction material to use when fabricating esophageal catheter balloons by hand. PMID:26077619

  9. Physical Characteristics of the Leaves and Latex of Papaya Plants Infected with the Papaya meleira Virus.

    PubMed

    Magaña-Álvarez, Anuar; Vencioneck Dutra, Jean Carlos; Carneiro, Tarcio; Pérez-Brito, Daisy; Tapia-Tussell, Raúl; Ventura, Jose Aires; Higuera-Ciapara, Inocencio; Fernandes, Patricia Machado Bueno; Fernandes, Antonio Alberto Ribeiro

    2016-01-01

    Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease. PMID:27092495

  10. Enhancing Student Writing and Computer Programming with LATEX and MATLAB in Multivariable Calculus

    ERIC Educational Resources Information Center

    Sullivan, Eric; Melvin, Timothy

    2016-01-01

    Written communication and computer programming are foundational components of an undergraduate degree in the mathematical sciences. All lower-division mathematics courses at our institution are paired with computer-based writing, coding, and problem-solving activities. In multivariable calculus we utilize MATLAB and LATEX to have students explore…

  11. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Applicability; description of the latex foam subcategory. 428.110 Section 428.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT...

  12. CHARACTERIZATION AND REDUCTION OF FORMALDEHYDE EMISSIONS FROM A LOW-VOC LATEX PAINT

    EPA Science Inventory

    The paper discusses the measurment and analysis of the patterns of formaldehyde emission from a low volatile organic compound (VOC) latex paint applied to gypsum board, using small environmental chamber tests. The formaldehyde emissions resulted in sharp increase of chamber air...

  13. Insights on the phytochemical profile (cyclopeptides) and biological activities of Calotropis procera latex organic fractions.

    PubMed

    Jucá, Thiago Lustosa; Ramos, Márcio Viana; Moreno, Frederico Bruno Mendes Batista; Viana de Matos, Mayara Patrícia; Marinho-Filho, José Delano Barreto; Moreira, Renato Azevedo; de Oliveira Monteiro-Moreira, Ana Cristina

    2013-01-01

    Calotropis procera is a medicinal plant whose pharmacological properties are associated with its latex. Here, the Calotropis procera latex fractions were investigated in an attempt to trace its phytochemical profile and measure its anti-inflammatory and toxicity activity. The crude latex was partitioned, yielding five fractions (49.4% hexane, 5.2% dichloromethane, 2.0% ethyl acetate, 2.1% n-butanol, and 41.1% aqueous). Phytochemical screening and spectroscopy analysis revealed that dichloromethane is the most chemically diverse fraction. Triterpenes were detected in both the hexane and dichloromethane fractions, while flavonoids were detected in the dichloromethane and ethyl acetate fractions. These fractions were cytotoxic to cancer cell lines (LD50 0.05 to 3.9  μ g/mL) and lethal to brine shrimp (LD50 10.9 to 65.7  μ g/mL). Reduced neutrophil migration in rats was observed in carrageenan-induced peritonitis for the dichloromethane (67%), ethyl acetate (56%), and aqueous (72%) fractions. A positive reaction with tolidine and ninhydrin suggested that cyclopeptides are in the ethyl acetate fraction. It is therefore concluded that Calotropis procera latex dichloromethane and ethyl acetate fractions exhibit both in vitro and in vivo activities as well as anti-inflammatory properties. Cyclopeptide detection is especially interesting because previous attempts to investigate these low-molecular cyclic amino acid sequences in C. procera have failed. PMID:24348174

  14. MEASUREMENTS OF VOLATILE ORGANIC COMPOUNDS AND PARTICLES DURING APPLICATION OF LATEX PAINT WITH AN AIRLESS SPRAYER

    EPA Science Inventory

    The paper discusses experiments, conducted at EPA's Indoor Air Quality Research House, to measure airborne concentrations of volatile organic compounds (VOCs) and particles during and following the spray-application of latex wall paint. (NOTE: Paint may be applied indoors by a v...

  15. An electrochemical and optical investigation of polypyrrole/polyethyleneoxide latex particles

    SciTech Connect

    Odegard, R.; Skotheim, T.A.; Lee, H.S. )

    1991-10-01

    This paper reports that submicronic polypyrrole/polyethylene-oxide (PPy/PEO) latex particles have been produced using PEO as the steric stabilizer and either FeCl{sub 3} or K{sub 2}S{sub 2}O{sub 8} as the oxidizing agent for pyrrole. Scanning electron micrographs show that the two types of PPy/PEO latex particles are of approximately the same size. From electrochemical and optical characterization (UV-vis spectra) of these particles, it was found that these latex particles can be electrochemically oxidized and reduced in an electrolyte of acetonitrile with 0.1M LiCF{sub 3}SO{sub 3}. The electrochemical and optical measurements indicate that the latex particles formed when using K{sub 2}S{sub 2}O{sub 8} as the oxidizing agent are more easily switched than the particles which are the result of applying FeCl{sub 3} as the oxidizing agent.

  16. Molecular detection of Papaya meleira virus in the latex of Carica papaya by RT-PCR.

    PubMed

    Araújo, Marília Mendes Melo de; Tavares, Eder Torres; Silva, Felipe Rodrigues da; Marinho, Vera Lúcia de Almeida; Júnior, Manoel Teixeira Souza

    2007-12-01

    A RT-PCR assay was developed for early and accurate detection of Papaya meleira virus (PMeV) in the latex from infected papayas. The meleira disease is characterized by an excessive exudation of more fluidic latex from fruits, leaves and stems. This latex oxidises and gives the fruit a "sticky" texture. In the field, disease symptoms are seen almost exclusively on fruit. However, infected plants can be a source of virus for dissemination by insects. Primers specific for PMeV were designed based on nucleotide sequences of the viral dsRNA obtained using a RT-RAPD approach. When tested for RT-PCR amplification, one of these primers (C05-3') amplified a 669-nucleotide fragment using dsRNA obtained from purified virus particles as a template. The translated sequence of this DNA fragment showed a certain degree of similarity to the amino acid sequence of RNA-dependent RNA polymerases from other dsRNA viruses. When used as the single primer in two RT-PCR kits available commercially, primer C05-3' also amplified the DNA fragment from papaya latex of infected, but not from healthy plants. The RT-PCR-based method developed in this study could simplify early plant disease diagnosis, assist in monitoring the dissemination of the pathogen within and between fields, and assist in guiding plant disease management.

  17. Physical Characteristics of the Leaves and Latex of Papaya Plants Infected with the Papaya meleira Virus.

    PubMed

    Magaña-Álvarez, Anuar; Vencioneck Dutra, Jean Carlos; Carneiro, Tarcio; Pérez-Brito, Daisy; Tapia-Tussell, Raúl; Ventura, Jose Aires; Higuera-Ciapara, Inocencio; Fernandes, Patricia Machado Bueno; Fernandes, Antonio Alberto Ribeiro

    2016-04-15

    Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease.

  18. Ethnobotanical Study of Latex Plants in the Maritime Region of Togo

    PubMed Central

    Hoekou, Yao Patrick; Tchacondo, Tchadjobo; Karou, Simplice Damintoti; Koudouvo, Koffi; Atakpama, Wouyo; Pissang, Passimna; Gbogbo, Apeti Koffi; Woegan, Agbelessessi Yawo; Batawila, Komlan; Akpagana, Koffi; Gbeassor, Messanvi

    2016-01-01

    Background: In Togo, a little is known about latex plants of the flora used for medicinal purposes. Objective: The aim of this study was to identify the latex plant species and their medicinal uses in the Maritime Region of Togo. Materials and Methods: The methodology was based on ethnobotanical semi-structural individual interviews of 220 informants. Quantitative ethnobotanical index was used to analyze the data. Results: A total of 33 latex plants species were recorded, from 12 botanical families and 24 genera. The most represented families were Euphorbiaceae and Moraceae with eight species each. The relative importance (RI) value of each species and the informant consensus factor (ICF) of the ailments categories showed that Pergularia daemia (Forssk.) Chiov. (RI = 2.00) and Euphorbia hirta L. (RI = 1.91) were the most versatile in relation to their uses, and infectious diseases (ICF = 0.922) were the category with the greatest consensus among 17 categories. Conclusion: These latex plants of Togolese flora are variously used in traditional medicine and it would be important to undertake further investigations in phytochemistry, pharmacology, and toxicology to validate their uses. Abbreviations Used: UV: use value ICF: informant consensus factor RI: relative importance PP: pharmacological properties attributed to a species for a specific ailments AC: ailment categories treated by a given species PMID:27034604

  19. Genotoxic potential of the latex from cotton-leaf physicnut (Jatropha gossypiifolia L.)

    PubMed Central

    de Almeida, Pedro Marcos; de Sousa Araújo, Silvany; Marin-Morales, Maria Aparecida; Benko-Iseppon, Ana Maria; Brasileiro-Vidal, Ana Christina

    2015-01-01

    Jatropha gossypiifolia L. (Euphorbiaceae), popularly known as cotton-leaf physicnut, is a milky shrub notable for its medicinal properties. The present study aimed to evaluate the toxic, cytotoxic and genotoxic effects of the latex of J. gossypiifolia, using Allium cepa L. as test system. Seeds of A. cepa were exposed to five concentrations of the latex (1.25; 2.5; 5; 10 and 20 mL/L) in order to evaluate parameters of toxicity (evaluation of root growth), cytotoxicity (mitotic index frequency) and genotoxicity (frequency of chromosome alterations). The latex showed a significant decrease in root mean growth value as well as mitotic index for the tested concentrations, except for 1.25 mL/L, when compared to results from the negative control. The 1.25, 2.5 and 5 mL/L concentrations induced significant chromo-some adherences, C-metaphases and/or chromosome bridges, as genotoxic effects. The significant frequency of chromosome bridges also indicated mutagenic potential for chromosomes of J. gossypiifolia as discussed in the paper. Considering that the latex is used in popular therapies, and that the test system A. cepa presents good correlation with tests carried out in mammals, it can be pointed out that its use for medicinal purposes may be harmful to human health especially if ingested. PMID:25983630

  20. Factors affecting the anthelmintic efficacy of papaya latex in vivo: host sex and intensity of infection.

    PubMed

    Luoga, Wenceslaus; Mansur, Fadlul; Lowe, Ann; Duce, Ian R; Buttle, David J; Behnke, Jerzy M

    2015-07-01

    The development of plant-derived cysteine proteinases, such as those in papaya latex, as novel anthelmintics requires that the variables affecting efficacy be fully evaluated. Here, we conducted two experiments, the first to test for any effect of host sex and the second to determine whether the intensity of the worm burden carried by mice would influence efficacy. In both experiments, we used the standard C3H mouse reference strain in which papaya latex supernatant (PLS) consistently shows >80 % reduction in Heligmosomoides bakeri worm burdens, but to broaden the perspective, we also included for comparison mice of other strains that are known to respond more poorly to treatment with papaya latex. Our results confirmed that there is a strong genetic influence affecting efficacy of PLS in removing adult worm burdens. However, there was no effect of host sex on efficacy (C3H and NIH) and no effect of infection intensity (C3H and BALB/c). These results offer optimism that plant-derived cysteine proteinases (CPs), such as these from papaya latex, can function as effective anthelmintics, with neither host sex nor infection intensity presenting further hurdles to impede their development for future medicinal and veterinary usage.

  1. Characterization of two different agglutinators in the latex fixation test, occurring in normal human sera

    PubMed Central

    Klein, F.; Valkenburg, H. A.; Van Zwet, Theda L.; Lafeber, Geertruida J. M.

    1966-01-01

    Using a sensitive modification of the latex fixation test it is possible to detect a small agglutinating effect in about 60 per cent of normal human sera, after these have been heated for 30 minutes at 56°. This was shown to be caused by an IgM globulin with the properties of a rheumatoid factor. The factor is able to react with human IgG globulin and may represent an antibody to the IgG part of circulating antigen—antibody complexes. The heat treatment probably inactivates an inhibitor of the latex fixation reaction. In addition all normal human sera give an agglutination reaction with IgG coated latex at incubation temperatures of 37° or lower. It was shown that these reactions are caused by a thermolabile, non-reducible component with a sedimentation constant of about 10. This component is probably identical with the complement component C'1q. The agglutinating activity was found in the α2—β1 region after electrophoresis of untreated serum, but in the slow γ region after treatment of the serum with EDTA. This kind of agglutination may cause false positive reactions in latex tests which are carried out at 37° or less. ImagesFIG. 1FIG. 3 PMID:4160336

  2. CHARACTERIZATION AND REDUCTION OF FORMALDEHYDE EMISSIONS FROM A LOW-VOC LATEX PAINT

    EPA Science Inventory

    The patterns of formaldehyde emission from a low volatile organic compound (VOC) latex paint applied to gypsum board were measured and analyzed by small environmental chamber tests. It was found that the formaldehyde emissions resulted in sharp increase of chamber air formaldehy...

  3. Physical Characteristics of the Leaves and Latex of Papaya Plants Infected with the Papaya meleira Virus

    PubMed Central

    Magaña-Álvarez, Anuar; Vencioneck Dutra, Jean Carlos; Carneiro, Tarcio; Pérez-Brito, Daisy; Tapia-Tussell, Raúl; Ventura, Jose Aires; Higuera-Ciapara, Inocencio; Fernandes, Patricia Machado Bueno; Fernandes, Antonio Alberto Ribeiro

    2016-01-01

    Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease. PMID:27092495

  4. Concentration of field and skim latex by microfiltration - membrane fouling and biochemical methane potential of serum.

    PubMed

    Thongmak, Narumol; Sridang, Porntip; Puetpaiboon, Udomphon; Grasmick, Alain

    2015-01-01

    Cross-flow microfiltration was used to concentrate field and skim latex suspensions and recover the smallest compounds (proteins, sugars, etc.) in permeate (serum solutions). The experiments were performed in a lab-scale microfiltration unit equipped with ceramic membranes. In continuous mode, the operations were performed at constant trans-membrane pressure (0.5 bars), constant cross-flow velocity (3 m/s) and constant temperature (28 ± 2°C). In retentate, the volumetric concentration factor was only close to 2 (about 54% of total solid content, TSC) when concentrating the field latex suspensions, and it reached 10 (close to 40% TSC) when concentrating skim latex suspensions. The quality of retentate suspensions let envisage a significant potential of industrial valorization. The membrane fouling rates appeared as an increasing function of dry rubber content suspension, and the main fouling origin (94%) was linked to a reversible accumulation of suspended compounds on the membrane surface. Permeate appeared as a clear yellow solution containing the smallest soluble organic fractions that show a high degree of biodegradability when using biochemical methane potential tests. The chemical oxygen demand (COD) removal was then higher than 92% and the methane production yield was close to 0.29 NLCH4/gCODremoved. The association of a membrane separation step and anaerobic digestion appeared, then, as a relevant solution to recover rubber content from skim latex suspensions and energy from the anaerobic digestion of serum. PMID:25812704

  5. Capsular gene typing of Streptococcus agalactiae compared to serotyping by latex agglutination.

    PubMed

    Yao, Kaihu; Poulsen, Knud; Maione, Domenico; Rinaudo, C Daniela; Baldassarri, Lucilla; Telford, John L; Sørensen, Uffe B Skov; Kilian, Mogens

    2013-02-01

    We evaluated three different PCR-based capsular gene typing methods applied to 312 human and bovine Streptococcus agalactiae (group B Streptococcus [GBS]) isolates and compared the results to serotyping results obtained by latex agglutination. Among 281 human isolates 27% could not be typed by latex agglutination. All 312 isolates except 5 could be typed by the three PCR methods combined. Two of these methods were multiplex assays. Among the isolates that were typeable by both latex agglutination and capsular gene typing, 94% showed agreement between the two methods. However, each of the PCR methods showed limitations. One of the methods did not include all 10 recognized serotypes, one misidentified eight isolates of serotypes Ib and IV as serotype Ia, and one did not distinguish between serotypes VII and IX. For five isolates that showed aberrant patterns in the capsular gene typing, long-range PCR targeting the cps operon disclosed large insertions or deletions affecting the cps gene cluster. A sensitive flow cytometric assay based on serotype-specific antibodies applied to 76 selected isolates that were nontypeable by latex agglutination revealed that approximately one-half of these did express capsular polysaccharide. A procedure for convenient and reliable capsular gene typing to be included in epidemiological and surveillance studies of S. agalactiae is proposed. PMID:23196363

  6. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    NASA Astrophysics Data System (ADS)

    Keong, C. C.; Zin, W. M. Wan; Ibrahim, P.; Ibrahim, S.

    2010-05-01

    Radiation prevulcanized natural rubber latex (RVNRL) was claimed to be more user friendly than natural rubber latex prevulcanized by sulphur curing system. The absence of Type IV allergy inducing chemicals in RVNRL make it a suitable material for manufacturing of many kinds of latex products, especially those come into direct contact with users. This paper reveals and discusses the findings of cytotoxicity test and safety evaluation on animal for RVNRL. The test was done on RVNRL films prepared by coagulant dipping method and RVNRL dipped products produced by latex dipped product manufacturers. Cytotocixity test was carried out on mammalian cell culture American Type Culture Collection CCL 81, Vero. Results indicated that no cytotoxic effect from RVNRL films and products was found on the cell culture. Two animal studies, namely dermal sensitization study and primary skin irritation study, were done on gloves made from RVNRL. Albino white guinea pigs were used as test subjects in dermal sensitization study and results showed no sensitization induced by the application of test material in the guinea pigs. Primary skin irritation study was done on New Zealand white rabbits and results showed that the product tested was not corrosive and was not a primary irritant

  7. The Puzzle of Septarian Concretions

    NASA Astrophysics Data System (ADS)

    John, C. M.; Dale, A.; Mozley, P.; Smalley, P. C.; Muggeridge, A. H.

    2014-12-01

    Carbonate concretions in clastic rocks and their septarian fracture fills act as 'time capsules', capturing the signatures of chemical and biological processes during diagenesis. However, many aspects of the formation of concretions and septarian fractures remain poorly understood, for although concretions occur in clastic rocks throughout the geological record, they are rarely documented in recent shallow-burial environments. Consequently, the depth and temperature at which concretion-forming processes occur are often poorly constrained. Carbonate clumped isotopes have recently been applied successfully to concretions and fracture fills that begin to unravel the conditions for the formation of concretions and septarian fractures. Here, we present carbonate clumped isotope results of fracture fills from eight different concretions from various locations, including multiple phases of fill in 4 concretions. Our results suggest that they precipitated over a range of temperatures (22°C - 85°C) from d18Oporewater values between -12‰ to 3‰ and within different d13Ccarbonate zones. The majority of fills precipitated at lower (<50°C) temperatures, although the fluids were not always meteoric. For 3 concretions containing fractures with multiple phases, the d18Oporewater becomes progressively heavier with each later phase and increasing temperature. The one exception to this is in the Barton Clay Formation (UK) where the fractures must have been continuously filled during exhumation as the latest cement phase is the coolest with a d18Oporewater more 18O-depleted than the earliest phase. Therefore, concretion growth must usually initiate early on (<~1 km burial), and subsequent fracturing is also usually early. However, the fracture infilling can occur over a range of depths and can record the diagenetic history of a formation. We gratefully acknowledge a BP and EPSRC Case Studentship for funding this project, and the Natural History Museum London for providing

  8. Evaluation of Polysaccharide-Based Latex Agglutination Assays for the Rapid Detection of Antibodies to Burkholderia pseudomallei

    PubMed Central

    Suttisunhakul, Vichaya; Chantratita, Narisara; Wikraiphat, Chanthiwa; Wuthiekanun, Vanaporn; Douglas, Zakiya; Day, Nicholas P. J.; Limmathurotsakul, Direk; Brett, Paul J.; Burtnick, Mary N.

    2015-01-01

    Melioidosis is a severe disease caused by the Gram-negative bacterium Burkholderia pseudomallei. Diagnosis of melioidosis currently relies on the isolation of B. pseudomallei from clinical samples, which can take several days. An indirect hemagglutination assay (IHA) is widely used for serodiagnosis, but it has a short shelf life, is poorly standardized, and requires a viable bacteria culture performed in a biosafety level 3 (BSL-3) laboratory. To improve the diagnostic methods, we have developed two rapid latex agglutination tests based on purified B. pseudomallei O-polysaccharide (OPS) and capsular polysaccharide (CPS) antigens. The immunodiagnostic potential of these tests was evaluated using serum from culture-confirmed melioidosis patients (N = 143) and healthy donors from either endemic (N = 199) or non-endemic areas (N = 90). The sensitivity of the OPS-based latex agglutination assay (OPS-latex; 84.4%) was significantly higher than both the CPS-latex (69.5%) (P < 0.001) and IHA (69.5%) (P = 0.001). When evaluated with Thai donor serum, the OPS-latex had comparable specificity (56.9%) to the CPS-latex (63.8%) (P = 0.053), but was significantly lower than the IHA (67.6%) (P = 0.002). In contrast, all tests with U.S. donor serum were highly specific (≥ 97.8%). These results suggest that polysaccharide-based latex agglutination assays may be useful for serodiagnosis of melioidosis in non-endemic areas. PMID:26123956

  9. Label-free quantitative proteomics reveals differentially regulated proteins in the latex of sticky diseased Carica papaya L. plants.

    PubMed

    Rodrigues, Silas P; Ventura, José A; Aguilar, Clemente; Nakayasu, Ernesto S; Choi, HyungWon; Sobreira, Tiago J P; Nohara, Lilian L; Wermelinger, Luciana S; Almeida, Igor C; Zingali, Russolina B; Fernandes, Patricia M B

    2012-06-18

    Papaya meleira virus (PMeV) is so far the only described laticifer-infecting virus, the causal agent of papaya (Carica papaya L.) sticky disease. The effects of PMeV on the laticifers' regulatory network were addressed here through the proteomic analysis of papaya latex. Using both 1-DE- and 1D-LC-ESI-MS/MS, 160 unique papaya latex proteins were identified, representing 122 new proteins in the latex of this plant. Quantitative analysis by normalized spectral counting revealed 10 down-regulated proteins in the latex of diseased plants, 9 cysteine proteases (chymopapain) and 1 latex serine proteinase inhibitor. A repression of papaya latex proteolytic activity during PMeV infection was hypothesized. This was further confirmed by enzymatic assays that showed a reduction of cysteine-protease-associated proteolytic activity in the diseased papaya latex. These findings are discussed in the context of plant responses against pathogens and may greatly contribute to understand the roles of laticifers in plant stress responses.

  10. Physical adsorption of anisotropic titania nanoparticles onto poly(2-vinylpyridine) latex and characterisation of the resulting nanocomposite particles.

    PubMed

    Fielding, Lee A; Armes, Steven P; Staniland, Paul; Sayer, Robert; Tooley, Ian

    2014-07-15

    Four poly(2-vinylpyridine) latexes with intensity-average mean diameters ranging between 246 and 955nm were prepared by aqueous emulsion polymerisation. These latexes were characterised by transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, aqueous electrophoresis, disc centrifuge photosedimentometry and thermogravimetry. The adsorption of rice grain-shaped nano-sized titania particles onto the surface of these latex particles from aqueous solution was investigated. It was found that the titania particles adsorb strongly at pH 10 and the optimal loading and packing density of titania was investigated for each latex. The resulting core-shell P2VP-titania nanocomposite particles were characterised in terms of their titania contents, surface coverages and colloidal stabilities. UV-Vis spectra were recorded for the titania nanoparticles, the original P2VP latexes and the poly(2-vinylpyridine)-titania nanocomposite particles. It was found that, for the larger nanocomposite particles, UV-Vis absorption was dominated by the latex core, whereas the smaller P2VP-titania nanocomposite particles exhibited UV attenuation to longer wavelengths compared to both the bare latex and the titania particles. The poly(2-vinylpyridine) cores were selectively removed by calcination of the nanocomposite particles and the resulting hollow titania structures were investigated by transmission electron microscopy. PMID:24863780

  11. Label-free quantitative proteomics reveals differentially regulated proteins in the latex of sticky diseased Carica papaya L. plants

    PubMed Central

    Rodrigues, Silas P.; Ventura, José A.; Aguilar, Clemente; Nakayasu, Ernesto S.; Choi, HyungWon; Sobreira, Tiago J. P.; Nohara, Lilian L.; Wermelinger, Luciana S.; Almeida, Igor C.; Zingali, Russolina B.; Fernandes, Patricia M. B.

    2012-01-01

    Papaya meleira virus (PMeV) is so far the only described laticifer-infecting virus, the causal agent of papaya (Carica papaya L.) sticky disease. The effects of PMeV on the laticifers’ regulatory network were addressed here through the proteomic analysis of papaya latex. Using both 1-DE- and 1D-LC-ESI-MS/MS, 160 unique papaya latex proteins were identified, representing 122 new proteins in the latex of this plant. Quantitative analysis by normalized spectral counting revealed 10 down-regulated proteins in the latex of diseased plants, 9 cysteine proteases (chymopapain) and 1 latex serine proteinase inhibitor. A repression of papaya latex proteolytic activity during PMeV infection was hypothesized. This was further confirmed by enzymatic assays that showed a reduction of cysteine-protease-associated proteolytic activity in the diseased papaya latex. These findings are discussed in the context of plant responses against pathogens and may greatly contribute to understand the roles of laticifers in plant stress responses. PMID:22465191

  12. Profiling Ethylene-Responsive Genes Expressed in the Latex of the Mature Virgin Rubber Trees Using cDNA Microarray.

    PubMed

    Nie, Zhiyi; Kang, Guijuan; Duan, Cuifang; Li, Yu; Dai, Longjun; Zeng, Rizhong

    2016-01-01

    Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2,973 unique genes (probes) was first developed and used to analyze the gene expression changes in the latex of the mature virgin rubber trees after ethephon treatment at three different time-points: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ -2 (q-value < 0.05) in ethephon-treated rubber trees compared with control trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes. The 163 ethylene-responsive genes were involved in several biological processes including organic substance metabolism, cellular metabolism, primary metabolism, biosynthetic process, cellular response to stimulus and stress. The presented data suggest that the laticifer water circulation, production and scavenging of reactive oxygen species, sugar metabolism, and assembly and depolymerization of the latex actin cytoskeleton might play important roles in ethylene-induced increase of latex production. The results may provide useful insights into understanding the molecular mechanism underlying the effect of ethylene on latex metabolism of H. brasiliensis.

  13. Characterization of Navajo Sandstone concretions: Mars comparison and criteria for distinguishing diagenetic origins

    NASA Astrophysics Data System (ADS)

    Potter, Sally L.; Chan, Marjorie A.; Petersen, Erich U.; Dyar, M. Darby; Sklute, Elizabeth

    2011-01-01

    The eolian Jurassic Navajo Sandstone spheroidal hydrous ferric oxide (HFO) concretions are divided into two size classes: macro-concretions of > 5 mm diameter and micro-concretions of < 5 mm diameter. Three internal structural end-members of macro-concretions are described as rind, layered, and solid. Two end-members of micro-concretions are rind and solid. Chemical and mineralogical gradients (μm- to mm-scale) are identified with QEMSCAN (Quantitative Elemental Mineralogy using a SCANning electron microscope) and visible to near infrared (VNIR) reflectance spectroscopy. Three HFO phases are identified using VNIR reflectance spectroscopy. An amorphous HFO phase is typically located in the rinds. Goethite is present along interior edges of rinds and throughout the interiors of layered and solid concretions. Hematite is present in the centers of rind concretions. A synthesis of petrographic, mineralogical and chemical analyses suggests that concretions grow pervasively (as opposed to radially expanding). Our model proposes that concretions precipitate initially as an amorphous HFO that sets the radius and retains some original porosity. Subsequent precipitation fills remaining pore space with younger mineral phases. Inward digitate cement crystal growth corroborates concretion growth from a set radius toward the centers. Internal structure is modified during late stage precipitation that diffuses reactants through semi-permeable rinds and overprints the interiors with younger cements. Physical characterization of textures and minerals provides diagnostic criteria for understanding how similar concretions ("blueberries") form in Meridiani Planum, Mars. The analogous Navajo Sandstone concretions show similar characteristics of in situ self-organized spacing, spheroidal geometries, internal structures, conjoined forms, and precursor HFO phases that dehydrate to goethite or hematite. These characteristics indicate a common origin via groundwater diagenesis.

  14. Sorptivity of fly ash concretes

    SciTech Connect

    Gopalan, M.K.

    1996-08-01

    A factorial experiment was designed to measure the sorptivity of cement and fly ash concretes in order to compare the durability of fly ash concrete against the cement concrete. Sorptivity measurements based on the capillary movement of water was made on three grades of cement concrete and six grades of fly ash mixes. The effect of curing was also studied by treating the samples in two curving conditions. A functional relationship of sorptivity against the strength, curing condition and fly ash content has been presented. The results were useful to analyze the factors influencing the durability of cement and fly ash concretes and to explain why some of the previously reported findings were contradictory. Curing conditions have been found to be the most important factor that affected the durability properties of fly ash concrete. When proper curing was provided, a mix with 40% fly ash was found to reduce the sorptivity by 37%. Under inadequate curing the sorptivity was found to increase by 60%. The influence of curing on cement concrete was found to be of much less importance.

  15. Testing of concrete by laser ablation

    DOEpatents

    Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.

    1997-01-07

    A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.

  16. Testing of concrete by laser ablation

    DOEpatents

    Flesher, Dann J.; Becker, David L.; Beem, William L.; Berry, Tommy C.; Cannon, N. Scott

    1997-01-01

    A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

  17. Joint interaction with embedded concretions: joint loading configurations inferred from propagation paths

    NASA Astrophysics Data System (ADS)

    McConaughy, David T.; Engelder, Terry

    1999-11-01

    The interaction between propagating joints and embedded concretions in a Devonian black shale near Seneca Lake, NY, permits identification of the loading configurations responsible for two joint sets of different ages striking at nearly the same orientation. The earlier set consists of systematic joints cut by later Alleghanian joints of the Appalachian Plateau. The later set consists of non-systematic curving cross joints that abut these same Alleghanian joints. Field evidence shows that concretions functioned as stiff inclusions in a compliant black shale. As a consequence of this elastic contrast, local perturbations in the remote stress field persisted around the concretions during burial, tectonic deformation, and exhumation. These stress perturbations influenced joint propagation paths of both joint sets. Our conclusions about loading configurations are based on finite-element modeling of the effect of the local stress perturbation on concretion-modified joint propagation. Modeling shows that the local stress perturbation from a thermoelastic loading was responsible for deflecting cross joints away from concretions in a curved propagation path near the concretion. This load configuration also led to arrest of cross joints before they penetrated the shale-concretion interface. At greater distances from the concretion, the propagation path of cross joints was controlled by the contemporary tectonic stress field. The interface between concretions and the surrounding shale was strongly bonded, as indicated by the crossing of the interface by some of the systematic ENE joints. Higher compressive stress levels within the concretions relative to the shale suppressed joint development in the concretion, causing the arrest of those joints once they had driven across the interface and a short distance into the concretion. Numerical modeling shows that interface penetration by the systematic ENE joints is consistent with a fluid load, the same loading configuration

  18. Effects of fertilizer and pesticides on concrete

    SciTech Connect

    Broder, M.F.; Nguyen, D.T.; Harner, A.L.

    1994-12-31

    Concrete is the most common material of construction for secondary containment of fertilizers and pesticides because of its relative low cost and structural properties. Concrete, however, is porous to some products it is designed to contain and is subject to corrosion. In this paper, concrete deterioration mechanisms and corrosion resistant concrete formulation are discussed, as well as exposure tests of various concrete mixes to some common liquid fertilizers and herbicides.

  19. A preliminary study on the anthelmintic activity of Calotropis procera latex against Haemonchus contortus infection in Najdi sheep.

    PubMed

    Al-Qarawi, A A; Mahmoud, O M; Sobaih; Haroun, E M; Adam, S E

    2001-01-01

    The anthelmintic activity of Calotropis procera latex was investigated in sheep that had been infected with single oral doses of 12000 infective Haemonchus contortus larvae. Inappetence, dullness, erosive abomasitis, decreased haemoglobin concentration and increased eosinophils were the main features of haemonchosis in the sheep. In the sheep treated with single oral doses of 0.01 ml or 0.02 ml/kg body weight of C. procera latex, egg production was significantly reduced, but not completely suppressed, and fewer adult Haemonchus worms were found in the abomasum. Although the appetite improved, the haemoglobin concentration and serum copper, iron and zinc levels were still reduced after therapy with Calotropis latex. Calotropis latex showed a concentration-dependent larvicidal activity in vitro within 20 min of application. PMID:11214673

  20. [Use of a calibrated melamine-formaldehyde latex for the luminescence microscopic study of phagocytosis in a macrophage culture].

    PubMed

    Korn, M Ia; Zhil'tsov, M P

    1984-05-01

    The possibility has been demonstrated of the use of calibrated melamine-formaldehyde latex for studying phagocytosis as an object not undergoing intracellular digestion. Latex was discovered to be actively phagocytized by macrophages and to exert no toxic action on them. A study was made of the time course of changes in the color and brightness of the fluorescence of the latex phagocytized particles in macrophages intravitally fluorochrominated by acridine orange. These changes were demonstrated to be analogous to those observed previously during phagocytosis of bacteria and other objects. The data obtained demonstrate once more the transition of the fluorescent complex from lysosomes to phagosomes and the lack of the relationship of these changes with intracellular death and digestion of the phagocytized objects. The possibility has been also shown to differentiate between phagocytized particles of latex and those located outside the cells.

  1. Ethylene-Induced Increase in Glutamine Synthetase Activity and mRNA Levels in Hevea brasiliensis Latex Cells.

    PubMed Central

    Pujade-Renaud, V.; Clement, A.; Perrot-Rechenmann, C.; Prevot, J. C.; Chrestin, H.; Jacob, J. L.; Guern, J.

    1994-01-01

    Ethylene, used as a stimulant of latex production in Hevea brasiliensis, significantly activates the regenerating metabolism within the laticiferous cells. In this context, attention was focused on glutamine synthetase (GS; EC 6.3.1.2), a key enzyme in nitrogen metabolism. A specific and significant activation of the cytosolic glutamine synthetase (GScyt) in the laticiferous cells after ethylene treatment parallels the increase of latex yield. A marked accumulation of the corresponding mRNA was found, but in contrast, a slight and variable increase of the polypeptide level is at the limit of detection by western blotting. The GS response to ethylene might be mediated by ammonia that increases in latex cytosol following ethylene treatment. The physiological significance for such a regulation by ethylene of the GScyt is discussed in terms of the nitrogen requirement for protein synthesis associated with latex regeneration. PMID:12232192

  2. Characterization of a sustainable sulfur polymer concrete using activated fillers

    DOE PAGESBeta

    Moon, Juhyuk; Kalb, Paul D.; Milian, Laurence; Northrup, Paul A.

    2016-01-02

    Sulfur polymer concrete (SPC) is a thermoplastic composite concrete consisting of chemically modified sulfur polymer and aggregates. This study focused on the characterization of a new SPC that has been developed as a sustainable construction material. It is made from industrial by-product sulfur that is modified with activated fillers of fly ash, petroleum refinery residual oil, and sand. Unlike conventional sulfur polymer cements made using dicyclopentadiene as a chemical modifier, the use of inexpensive industrial by-products enables the new SPC to cost-effectively produce sustainable, low-carbon, thermoplastic binder that can compete with conventional hydraulic cement concretes. A series of characterization analysesmore » was conducted including thermal analysis, X-ray diffraction, and spatially-resolved Xray absorption spectroscopy to confirm the polymerization of sulfur induced from the presence of the oil. In addition, mechanical testing, internal pore structure analysis, and scanning electron microscope studies evaluate the performance of this new SPC as a sustainable construction material with a reduced environmental impact.« less

  3. Personal Exposure to Inhalable Dust and the Specific Latex Aero-Allergen, Hev b6.02, in Latex Glove Manufacturing in Thailand

    PubMed Central

    Sanguanchaiyakrit, Nuthchyawach; Povey, Andrew C.; de Vocht, Frank

    2014-01-01

    Objectives: Latex product manufacturing is an important industry in south-east Asia but has the potential for considerable occupational exposure of workers to latex allergens. Although exposure to latex allergens can result in adverse health reactions, few studies to characterize this exposure have been conducted to date. This study therefore aimed to characterize current airborne inhalable dust and the specific allergen, Hev b 6.02, exposures in this industry in Thailand. Methods: Workers were recruited from three factories in the southern part of Thailand. Full-shift inhalable dust personal air sampling was conducted using IOM sampling heads equipped with polytetrafluoroethylene filters at a 2.0 l min−1 flowrate. After weighing to determine inhalable dust levels, filters were extracted and analysed for Hev b 6.02 using an enzyme immunometric assay. Results: Two hundred and seventy-five workers agreed to participate, resulting in a total of 292 measurements. Geometric mean (GM) personal exposure to inhalable dust was 0.88mg m–3, but individual exposures up to 12.34mg m–3 were measured. The pattern of exposure was similar across factories, with highest exposures in the stripping (GM 2.08–4.05mg m–3 for the 3 factories) and tumbling departments (1.11–2.17mg m–3). Within-worker (day-to-day) variability contributed 92% to total variability. The Hev b 6.02 exposure pattern was similar with time-weighted average GM exposure levels in the oldest factory ranging from 8.7mg m–3 in the laboratory to 30.2mg m–3 in the stripping department. In contrast to inhalable dust exposure, total exposure variability was primary driven by variability between workers (67%). Conclusions: Workers in these latex product factories get routinely exposed to measurable Hev b 6.02 levels, which may give rise to increased incidence of allergic symptoms and occupational asthma. Also, in this measurement campaign a 10mg m–3, but not 15mg m–3, occupational exposure limit for

  4. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    PubMed

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping. PMID:26358051

  5. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    PubMed

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping.

  6. Protective coatings for concrete

    SciTech Connect

    NAGY, KATHRYN L.; CYGAN, RANDALL T.; BRINKER, C. JEFFREY; SELLINGER, ALAN

    2000-05-01

    The new two-layer protective coating developed for monuments constructed of limestone or marble was applied to highway cement and to tobermorite, a component of cement, and tested in batch dissolution tests. The goal was to determine the suitability of the protective coating in retarding the weathering rate of concrete construction. The two-layer coating consists of an inner layer of aminoethylaminopropylsilane (AEAPS) applied as a 25% solution in methanol and an outer layer of A2** sol-gel. In previous work, this product when applied to calcite powders, had resulted in a lowering of the rate of dissolution by a factor of ten and was shown through molecular modeling to bind strongly to the calcite surface, but not too strongly so as to accelerate dissolution. Batch dissolution tests at 22 C of coated and uncoated tobermorite (1.1 nm phase) and powdered cement from Gibson Blvd. in Albuquerque indicated that the coating exhibits some protective behavior, at least on short time scales. However, the data suggest that the outer layer of sol-gel dissolves in the high-pH environment of the closed system of cement plus water. Calculated binding configuration and energy of AEAPS to the tobermorite surface suggests that AEAPS is well-suited as the inner layer binder for protecting tobermorite.

  7. Becoming Reactive by Concretization

    NASA Technical Reports Server (NTRS)

    Prieditis, Armand; Janakiraman, Bhaskar

    1992-01-01

    One way to build a reactive system is to construct an action table indexed by the current situation or stimulus. The action table describes what course of action to pursue for each situation or stimulus. This paper describes an incremental approach to constructing the action table through achieving goals with a hierarchical search system. These hierarchies are generated with transformations called concretizations, which add constraints to a problem and which can reduce the search space. The basic idea is that an action for a state is looked up in the action table and executed whenever the action table has an entry for that state; otherwise, a path is found to the nearest (cost-wise in a graph with costweighted arcs) state that has a mappring from a state in the next highest hierarchy. For each state along the solution path, the successor state in the path is cached in the action table entry for that state. Without caching, the hierarchical search system can logarithmically reduce search. When the table is complete the system no longer searches: it simply reacts by proceeding to the state listed in the table for each state. Since the cached information is specific only to the nearest state in the next highest hierarchy and not the goal, inter-goal transfer of reactivity is possible. To illustrate our approach, we show how an implemented hierarchical search system can completely reactive.

  8. Biological safety evaluation of the modified urinary catheter.

    PubMed

    Kowalczuk, Dorota; Przekora, Agata; Ginalska, Grazyna

    2015-04-01

    The purpose of this study was to evaluate in vitro safety of the novel tosufloxacin (TOS)-treated catheters with the prolonged antimicrobial activity. The test samples of silicone latex catheter were prepared by the immobilization of TOS on chitosan (CHIT)-coated catheter by means of covalent bonds and non-covalent interactions. Each step of the modification process of catheter surface was observed using ATR-Fourier transform infrared spectroscopy. In vitro cytotoxicity of the modified and unmodified catheters was assessed by direct and indirect tests in accordance with ISO standards using green monkey kidney (GMK) cell line. The MTT, lactate dehydrogenase activity (LDH), WST-8, Sulforhodamine B (SRB) test results and microscopic observation clearly indicated that unmodified silicone latex catheters decrease cell metabolic activity, act as a cytotoxic agent causing cell lysis and induce cell death through necrotic or apoptotic process. We suggest that chitosan coat with TOS immobilized limits leaching of harmful agents from silicone latex material, which significantly enhances survivability of GMK cells and therefore is quite a good protection against the cytotoxic effect of this material. PMID:25686950

  9. Modified cyanobacteria

    DOEpatents

    Vermaas, Willem F J.

    2014-06-17

    Disclosed is a modified photoautotrophic bacterium comprising genes of interest that are modified in terms of their expression and/or coding region sequence, wherein modification of the genes of interest increases production of a desired product in the bacterium relative to the amount of the desired product production in a photoautotrophic bacterium that is not modified with respect to the genes of interest.

  10. Antioxidant and antiapoptotic activities of Calotropis procera latex on Catfish (Clarias gariepinus) exposed to toxic 4-nonylphenol.

    PubMed

    Sayed, Alaa El-Din H; Mohamed, Nadia H; Ismail, Mady A; Abdel-Mageed, Wael M; Shoreit, Ahmed A M

    2016-06-01

    Calotropis procera L. is known as medicinal plant. The Phytochemical analyzes of its latex revealed that it possessed antioxidants, namely terpenes, phenolic compounds and cardenolides, flavonoids and saponins, while tannins, alkaloids and resin were absent in moderate to high concentration. In the present study, the role of latex of Calotropis procera as antioxidant and antiapoptotic was reported. To carry out this aim, fishes were exposed to 100 µg l(-1) 4-nonylphenol as chemical pollutant. The enzymes, superoxidase dismutase, catalase, acetlycholinstrase (AchE), glutathione s-transferase, cortisol, G6PDH) and apoptotic cells increased significantly (p<0.05) accompanied by irregular disturbance of (Na(+), K(+)) ions in the presence of 4-nonylphenol. On the other hand, these enzymes, ions, and apoptotic cells decreased normally and significantly (p<0.05) in the presence of latex. Total phenol content, total capacity antioxidant, reducing power decrease significantly (p<0.05) in the presence of 4-nonylphenol and increase normally in the presence of latex. Latex was used for the first time to protect catfish after 4-nonylphenol exposure. Our study confirms that crude latex of Calotropis procera possessed antioxidant and antiapoptotic activities against the toxicity of 4-Nonylphenol. PMID:26946283

  11. A Comparative Study on the Adsorption of Triton X-100 and Tween 20 onto Latexes with Different Interfacial Properties

    PubMed

    Martín-Rodríguez; Cabrerizo-Vílchez; Hidalgo-Álvarez

    1997-03-01

    In this paper we have studied the adsorption of two nonionic surfactants, Triton X-100 and Tween 20 (polyoxyethylene (20) sorbitan monolaurate) onto latexes with different interfacial properties. Four different samples of polystyrene beads were used in this study. A hydrophobic sample was prepared by conventional emulsion polymerization of styrene. Hydrophilic polymer colloids were prepared by the emulsifier-free emulsion copolymerization of styrene and 2-hydroxyethylmethacrylate in different proportions and acrylic acid. In all cases potassium persulfate was used as initiator. In order to consider the mechanism of the adsorption at the different liquid-solid interfaces, adsorption isotherms under different pH and ionic strength conditions were performed. Electrokinetic characterization and colloidal stability of bare hydrophobic and hydrophilic latexes and the surfactant-latex complexes were compared to understand the effect of the nonionic surfactant on the electric double layer structure. The results showed that Tween 20 and Triton X-100 are adsorbed in the same way on surfaces with different polarity but in different amounts. Hydrophobic interaction is the main driving force in the adsorption. The effect of the adsorption on the electrokinetic properties and stability of the latexes was found to be different for hydrophobic and hydrophilic latexes as a consequence of the dissimilar interfacial properties of these two latex samples. PMID:9245323

  12. [Methicillin resistance detection in Staphylococcus aureus: comparison between conventional methods and MRSA-Screen latex agglutination technique].

    PubMed

    Soloaga, R; Corso, A; Gagetti, P; Faccone, D; Galas, M

    2004-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen that has emerged over the last four decades, causing both nosocomial and community-acquired infections. Rapid and accurate detection of methicillin resistance in S. aureus is important for the use of appropriate antimicrobial therapy and for the control of nosocomial spread of MRSA strains. We evaluated the efficiency of conventional methods for detection of methicillin resistance such as the disk diffusion, agar dilution, oxacillin agar screen test, and the latex agglutination test MRSA-Screen latex, in 100 isolates of S. aureus, 79 mecA positive and 21 mecA negative. The MRSA-Screen latex (Denka Seiken, Niigata, Japón), is a latex agglutination method that detects the presence of PLP-2a, product of mecA gene in S. aureus. The PCR of the mecA gene was used as the "gold standard" for the evaluation of the different methods tested. The percentages of sensitivity and specificity were as follows: disk difusión 97 and 100%, agar dilution 97 and 95%, oxacillin agar screen test 100 and 100%, and MRSA-Screen latex, 100 and 100 %. All methods presented high sensitivity and specificity, but MRSA-Screen latex had the advantage of giving a reliable result, equivalent to PCR, in only 15 minutes.

  13. Characterization of proteins in latex of the opium poppy (Papaver somniferum) using two-dimensional gel electrophoresis and microsequencing.

    PubMed

    Decker, G; Wanner, G; Zenk, M H; Lottspeich, F

    2000-10-01

    The opium poppy (Papaver somniferum) belongs to the group of latex-containing plants. Latex is the milky-like fluid within laticifer cells. In this study, poppy latex was analyzed with respect to ultrastructure, alkaloid, and protein content. The main goal of this project was the examination of the proteins by two-dimensional gel electrophoresis. In a proteomics approach, we investigated two main fractions of the latex, namely the cytosolic serum and the sedimented fraction containing the alkaloid-accumulating vesicles. Of the serum, representing the protein-rich part of the latex, 75 spots were analyzed by internal peptide microsequencing, followed by a database searching. For 69 proteins a function could be assigned due to homology to known proteins, whereas six spots could not be identified. Furthermore, codeinone reductase, a representative of the specific enzyme system in morphine biosynthesis, could be detected within the cytosolic serum fraction. In the vesicle-containing pellet, 23 protein spots were analyzed. An attempt was also made to separate the vesicle pellet by density centrifugation, followed by investigation of the alkaloid content, ultrastructure, and protein pattern. This study describes the first database of soluble proteins present in the latex of P. somniferum

  14. Latex-protein complexes from an acute phase recombinant antigen of Toxoplasma gondii for the diagnosis of recently acquired toxoplasmosis.

    PubMed

    Peretti, Leandro E; Gonzalez, Verónica D G; Marcipar, Iván S; Gugliotta, Luis M

    2014-08-01

    The synthesis and characterization of latex-protein complexes (LPC), from the acute phase recombinant antigen P35 (P35Ag) of Toxoplasma gondii and "core-shell" carboxylated or polystyrene (PS) latexes (of different sizes and charge densities) are considered, with the aim of producing immunoagglutination reagents able to detect recently acquired toxoplasmosis. Physical adsorption (PA) and chemical coupling (CC) of P35Ag onto latex particles at different pH were investigated. Greater amounts of adsorbed protein were obtained on PS latexes than on carboxylated latexes, indicating that hydrophobic forces govern the interactions between the protein and the particle surface. In the CC experiments, the highest amount of bound protein was obtained at pH 6, near the isoelectric point of the protein (IP=6.27). At this pH, it decreased both the repulsion between particle surface and protein, and the repulsion between neighboring molecules. The LPC were characterized and the antigenicity of the P35Ag protein coupled on the particles surface was evaluated by Enzyme-Linked ImmunoSorbent Assay (ELISA). Results from ELISA showed that the P35Ag coupled to the latex particles surface was not affected during the particles sensitization by PA and CC and the produced LPC were able to recognize specific anti-P35Ag antibodies present in the acute phase of the disease.

  15. Evaluation of a latex agglutination assay for the identification of Burkholderia pseudomallei and Burkholderia mallei.

    PubMed

    Duval, Brea D; Elrod, Mindy G; Gee, Jay E; Chantratita, Narisara; Tandhavanant, Sarunporn; Limmathurotsakul, Direk; Hoffmaster, Alex R

    2014-06-01

    Cases of melioidosis and glanders are rare in the United States, but the etiologic agents of each disease (Burkholderia pseudomallei and Burkholderia mallei, respectively) are classified as Tier 1 select agents because of concerns about their potential use as bioterrorism agents. A rapid, highly sensitive, and portable assay for clinical laboratories and field use is required. Our laboratory has further evaluated a latex agglutination assay for its ability to identify B. pseudomallei and B. mallei isolates. This assay uses a monoclonal antibody that specifically recognizes the capsular polysaccharide produced by B. pseudomallei and B. mallei, but is absent in closely related Burkholderia species. A total of 110 B. pseudomallei and B. mallei were tested, and 36 closely related Burkholderia species. The latex agglutination assay was positive for 109 of 110 (99.1% sensitivity) B. pseudomallei and B. mallei isolates tested.

  16. Correlation between particle deformation kinetics and polymer interdiffusion kinetics in drying latex films.

    PubMed

    Pohl, Katja; Adams, Jörg; Johannsmann, Diethelm

    2013-09-10

    Using an experimental setup which determines the turbidity of the sample and the efficiency of Förster resonance energy transfer (FRET) at the same time, we have correlated the particle deformation kinetics in a drying latex film, quantified by light scattering with the kinetics of polymer interdiffusion. Interdiffusion was quantified making use of energy transfer (FRET) between donor molecules and acceptor molecules, bound to polymer chains on different particles. When the chains cross the interparticle boundaries, the rate of energy transfer increases. The latex was prepared by miniemulsion polymerization. The amount of emulsifier employed during polymerization had a pronounced effect on the relative timing of interdiffusion and particle deformation. Increasing the amount of emulsifier delayed the onset of interdiffusion relative to the time when the film became transparent. This is mostly the consequence of a size effect, as opposed to surfactant acting as a barrier for transport.

  17. Modeling the VOC emissions from interior latex paint applied to gypsum board

    SciTech Connect

    Guo, Z.; Fortmann, R.; Marfiak, S.; Tichenor, B.; Sparks, L.

    1997-09-01

    The paper discusses modeling volatile organic compound (VOC) emissions from indoor latex paint applied to gypsum board. An empirical source model for a porous substrate was developed that takes both the wet- and dry-stage emission into consideration. Tests in the U.S. EPA`s Source Characterization Laboratory showed that common interior surfaces such as gypsum board and carpet could absorb significant amounts of latex paint VOCS from the air, and that they were re-emitted very slowly. An indoor air quality model incorporating the source model, an irreversible sink model, and the air movement data obtained from tracer gas tests made satisfactory predictions for the VOC levels in a test house.

  18. Rapid and simple method for serotyping of staphylocoagulase using polystyrene latex particles.

    PubMed

    Kouguchi, Yoshihiro; Fujiwara, Takako; Teramoto, Miki

    2009-01-01

    The serotyping of staphylocoagulase is widely used in Japan. However, the conventional immunoassay based on neutralization of the antisera is so laborious and time-consuming that it is not widely used in the other countries. In order to overcome these drawbacks we developed a novel staphylocoagulase serotyping method based on a microplate format using polystyrene latex particles. Addition of latex particles promotes the formation of fibrin complexes, which represents a more rapidly and easily detected endpoint. For 83 strains, 90% were classified into serotypes within 3 h, and there was no discrepancy in the results between our method and the conventional method. These results indicate that the present microplate method is rapid, simple, and interpretable. PMID:20528093

  19. Polystyrene latex separations by continuous flow electrophoresis on the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Snyder, R. S.; Rhodes, P. H.; Miller, T. Y.; Micale, F. J.; Mann, R. V.

    1986-01-01

    The seventh mission of the Space Shuttle carried two NASA experiments in the McDonnell Douglas Astronautics Corporation continuous flow electrophoresis system. The objectives were to test the operation of continuous flow electrophoresis in a reduced gravity environment using stable particles with established electrokinetic properties and specifically to evaluate the influence of the electrical properties of the sample constituents on the resolution of the continuous flow electrophoretic device. Polystrene latex microspheres dispersed in a solution with three times the electrical conductivity of the curtain buffer separated with a significantly larger band spread compared to the second experiment under matched conductivity conditions. It is proposed that the sample of higher electrical conductivity distorted the electric field near the sample stream so that the polystyrene latex particles migrated toward the chamber walls where electroosmosis retarded and spread the sample.

  20. Tensile properties of latex paint films with TiO2 pigment

    NASA Astrophysics Data System (ADS)

    Hagan, Eric W. S.; Charalambides, Maria N.; Young, Christina T.; Learner, Thomas J. S.; Hackney, Stephen

    2009-05-01

    The tensile properties of latex paint films containing TiO2 pigment were studied with respect to temperature, strain-rate and moisture content. The purpose of performing these experiments was to assist museums in defining safe conditions for modern paintings held in collections. The glass transition temperature of latex paint binders is in close proximity to ambient temperature, resulting in high strain-rate dependence in typical exposure environments. Time dependence of modulus and failure strain is discussed in the context of time-temperature superposition, which was used to extend the experimental time scale. Nonlinear viscoelastic material models are also presented, which incorporate a Prony series with the Ogden or Neo-Hookean hyperelastic function for different TiO2 concentrations.

  1. [Use of a latex-agglutination test for determining anti-measles antibody titer].

    PubMed

    Aleksander, S K; Lukin, Iu V; Iuminova, N V; Krasnova, V P; Andzhaparidze, O G

    1995-01-01

    A new diagnostic agent for microtitration of antimeasles antibodies, making use of polyacrolein microspheres conjugated with purified measles virus has been developed. Parallel titration of blood sera of children and adults in latex agglutination test and in routine test (hemagglutination inhibition, passive hemagglutination, immunofluorescent tests) demonstrated a sufficient specificity of the new test, sensitivity compatible to that of hemagglutination inhibition, and correlation of the results of all tests.

  2. Novel one-pot synthesis of magnetite latex nanoparticles by ultrasound irradiation.

    PubMed

    Teo, Boon M; Chen, Fei; Hatton, T Alan; Grieser, Franz; Ashokkumar, Muthupandian

    2009-03-01

    A simple and efficacious procedure for the synthesis of magnetite nanoparticles has been achieved via a sonochemical miniemulsion polymerization process. The sonochemically synthesized magnetite encapsulated polymer latex particles exhibit excellent colloidal stability and strong magnetic properties, and are of a size that makes them technologically relevant. This novel method may be readily extended to the preparation of multiple combinations of different polymers and encapsulated materials.

  3. Extraction and purification of curcain, a protease from the latex of Jatropha curcas Linn.

    PubMed

    Nath, L K; Dutta, S K

    1991-02-01

    A proteolytic enzyme, curcain, has been extracted from the latex of Jatropha curcas Linn. The enzyme was purified by chromatography on carboxymethyl cellulose and gel filtration on Sephadex G-200. The homogeneity of protein associated with curcain was established by non-denatured polyacrylamide gel electrophoresis using a discontinuous buffer system. The molecular weight of curcain was estimated by Sephadex G-100 gel filtration using a calibration curve of standard proteins to be around 22,000 daltons.

  4. Respiratory function and immunological status in workers employed in a latex glove manufacturing plant.

    PubMed

    Zuskin, E; Mustajbegovic, J; Kanceljak, B; Schachter, E N; Macan, J; Budak, A

    1998-02-01

    A study was performed in 17 female workers employed in a latex glove manufacturing plant. The mean age of these workers was 42 years and the mean duration of their employment was 19 years. The employees were primarily nonsmokers or light smokers. The presence of chronic respiratory symptoms and acute work-related symptoms was recorded for these workers. Ventilatory capacity was measured during the morning work shift by recording maximum expiratory flow-volume curves from which forced vital capacity (FVC), 1-second forced expiratory volume (FEV1) and maximum expiratory flow at 50%, and the last 25% of the vital capacity (FEF50, FEF75) were measured. A control group of 17 nonexposed women workers was also studied. The prevalence of chronic respiratory symptoms was greater among latex workers than among control confectionary packer workers, varying from 5.9% (vs. 0% in controls) for occupational asthma to 58.8% (vs. 0% in controls) for dyspnea grades 3 or 4. There was also a high prevalence of acute work-related symptoms in this industry, in particular, eye irritation (76.5%), dryness of the nose (70.6%), throat burning (70.6%), dryness of the throat (64.7%), and cough (58.8%). Among exposed workers, measured ventilatory capacity data were significantly lower than among controls, particularly FEF75 (75.1% +/- 10.5%). One of the 17 studied workers (5.9%) had a positive skin reaction to latex and had symptoms compatible with occupational asthma. Our data suggest that in addition to occupational asthma, the manufacture of latex gloves is associated with frequent, nonspecific respiratory findings. PMID:9438050

  5. Local imipenem activity against Pseudomonas aeruginosa decreases in vivo in the presence of siliconized latex.

    PubMed

    Pichardo, C; Conejo, M C; Docobo-Pérez, F; Velasco, C; López-Rojas, R; García, I; Pachón-Ibáñez, M E; Rodríguez, J M; Pachón, J; Pascual, A

    2011-02-01

    Zinc eluted from siliconized latex (SL) increases resistance of Pseudomonas aeruginosa to imipenem in vitro. A foreign body peritonitis model was used to evaluate the activity of imipenem using SL or silicone (S) implants. No differences were observed in mortality, positive blood cultures and tissue bacterial counts between SL and S implants. Implant-associated counts, however, were significantly higher in the SL group. It is concluded that SL decreases the activity of imipenem against P. aeruginosa. PMID:20936490

  6. Decolorization of crude latex by activated charcoal, purification and physico-chemical characterization of religiosin, a milk-clotting serine protease from the latex of Ficus religiosa.

    PubMed

    Kumari, Moni; Sharma, Anurag; Jagannadham, M V

    2010-07-14

    The crude latex of Ficus religiosa is decolorized by activated charcoal. Decolorization follows the Freundlich and Langmuir equations. A serine protease, named religiosin, has been purified to homogeneity from the decolorized latex using anion exchange chromatography. Religiosin is a glycoprotein with a molecular mass of 43.4 kDa by MALDI-TOF. Religiosin is an acidic protein with a pI value of 3.8 and acts optimally at pH 8.0-8.5 and temperature 50 degrees C. The proteolytic activity of religiosin is strongly inhibited by PMSF and chymostatin indicating that the enzyme is a serine protease. The extinction coefficient (epsilon(1%)(280)) of religiosin is 29.47 M(-1) cm(-1)with 16 tryptophan, 26 tyrosine, and 11 cysteine residues per molecule. The enzyme shows broad substrate specificity against natural as well as synthetic substrates with an apparent K(m) of 0.066 mM and 6.25 mM using casein and Leu-pNA, respectively. MS/MS analysis confirms the novelty of the enzyme. Religiosin is highly stable against denaturants, metal ions, and detergents as well as over a wide range of pH and temperature. In addition, the enzyme exhibits milk-clotting as well as detergent activity. PMID:20560603

  7. Sequence and Expression Analyses of Ethylene Response Factors Highly Expressed in Latex Cells from Hevea brasiliensis

    PubMed Central

    Piyatrakul, Piyanuch; Yang, Meng; Putranto, Riza-Arief; Pirrello, Julien; Dessailly, Florence; Hu, Songnian; Summo, Marilyne; Theeravatanasuk, Kannikar; Leclercq, Julie; Kuswanhadi; Montoro, Pascal

    2014-01-01

    The AP2/ERF superfamily encodes transcription factors that play a key role in plant development and responses to abiotic and biotic stress. In Hevea brasiliensis, ERF genes have been identified by RNA sequencing. This study set out to validate the number of HbERF genes, and identify ERF genes involved in the regulation of latex cell metabolism. A comprehensive Hevea transcriptome was improved using additional RNA reads from reproductive tissues. Newly assembled contigs were annotated in the Gene Ontology database and were assigned to 3 main categories. The AP2/ERF superfamily is the third most represented compared with other transcription factor families. A comparison with genomic scaffolds led to an estimation of 114 AP2/ERF genes and 1 soloist in Hevea brasiliensis. Based on a phylogenetic analysis, functions were predicted for 26 HbERF genes. A relative transcript abundance analysis was performed by real-time RT-PCR in various tissues. Transcripts of ERFs from group I and VIII were very abundant in all tissues while those of group VII were highly accumulated in latex cells. Seven of the thirty-five ERF expression marker genes were highly expressed in latex. Subcellular localization and transactivation analyses suggested that HbERF-VII candidate genes encoded functional transcription factors. PMID:24971876

  8. Bioseparation of papain from Carica papaya latex by precipitation of papain-poly (vinyl sulfonate) complexes.

    PubMed

    Braia, Mauricio; Ferrero, Maximiliano; Rocha, María Victoria; Loureiro, Dana; Tubio, Gisela; Romanini, Diana

    2013-09-01

    The formation of insoluble complexes between enzymes and polyelectrolytes is a suitable technique for isolating these biomolecules from natural sources, because it is a simple and rapid technique that allows the concentration of the protein. This technique can be used in most purification protocols at the beginning of the downstream process. The aim of this investigation is to isolate papain from Carica papaya latex by precipitation of insoluble complexes between this enzyme and poly (vinyl sulfonate). The papain-poly (vinyl sulfonate) complex was insoluble at pH lower than 6, with a PVS/PAP stoichiometric ratio of 1:279. Ionic strength affected the complex formation. The presence of the polymer increased the enzymatic activity and protected the enzyme from autodegradation. The optimal conditions for the formation of insoluble papain-polyelectrolyte complex formation were applied to C. papaya latex and a high recovery was obtained (around 86%) and a purification factor around 2. This method can be applied as an isolation method of papain from C. papaya latex or as a first step in a larger purification strategy.

  9. Development of a Specific Latex Agglutination Test to Detect Antibodies of Enterovirus 71.

    PubMed

    Qin, Bo; Zhang, Jianhua; Xie, Wenhao; Liu, Xuehong; He, Tingting; Chen, Jinkun; Dong, Xuejun

    2015-10-01

    A latex agglutination test (LAT) was developed for the rapid detection of antibodies against the VP1 or VP1 proteins of Enterovirus 71 (EV71). The proteins of interest including prokaryotically expressed VP1 and two strains of anti-VP1 monoclonal antibody (McAb) against EV71 were covalently linked to carboxylated latex using ethyl-dimethyl-amino-propyl carbodiimide (EDC) to prepare sensitized latex beads. LAT was evaluated by an enzyme-linked immunosorbent assay (ELISA) as a reference test. The VP1-LAT showed a sensitivity of 87.0%, specificity of 88.9%, and an agreement ratio of 90.0% in detecting VP1 in 100 serum samples from experimentally infected mice, whereas these values were 86.8, 96.7, and 93.3%, respectively, for 608 clinical human serum samples. The VP1-LAT has advantages over other assays in terms of low cost, rapidity, chemical stability, high sensitivity, repeatability, and specificity. The LAT established in the present study is a rapid and simple test suitable for field monitoring of antibodies against VP1-EV71. PMID:26363276

  10. Procoagulant activity of Calotropis gigantea latex associated with fibrin(ogen)olytic activity.

    PubMed

    Rajesh, R; Raghavendra Gowda, C D; Nataraju, A; Dhananjaya, B L; Kemparaju, K; Vishwanath, B S

    2005-07-01

    The latex of Calotropis gigantea is a rich source of useful components that has medicinal properties and one of the main applications is in controlling bleeding. The crude latex extract contained many proteins, which are highly basic in nature and exhibited strong proteolytic activity. The crude extract hydrolyses casein, human fibrinogen and crude fibrin clot in a dose-dependent manner. The hydrolyzing activity was completely inhibited by IAA indicating they belong to the super family, cysteine proteases. Crude extract hydrolyses Aalpha, Bbeta and gamma subunits of fibrinogen. Among all the subunits the preferential subunit to get hydrolyzed was Aalpha followed by Bbeta and gamma subunit is highly resistant and hydrolyzed at higher protein concentration or over a prolonged incubation time. The crude extract hydrolysis crude fibrin clot strongly compared to trypsin and papain. Pharmacologically the crude extract is hemorrhagic and induces skin hemorrhage at >75 microg and reduces the coagulation time of citrated plasma from 150 to 47 s and promotes blood coagulation. Procoagulation and blood clot hydrolysis are important in wound healing process. This is due to unique cysteine proteases of plant latex and is responsible for the pharmacological actions observed in folk medicine.

  11. Film formation from monodisperse acrylic latices 5. Drying and ageing in coalescing agent containing latex films.

    PubMed

    Zohrehvand, Shiva; Te Nijenhuis, Klaas

    2005-08-01

    The influences of drying temperature, ageing time and ageing temperature on the film formation in coalescing agent containing latex films were investigated via turbidity measurements and atomic force microscopy. Coalescing agents used are 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TEX) and ethylene glycol monobutyl ether (EB). Latex films were dried at different temperatures. At a drying temperature of 40 degrees C, the differences in immersion patterns of neat and 1% coalescing agent containing latex films are too small to show significant improvement in film formation during 1 h of drying. Increase of the temperature from 40 to 50 degrees C, however, causes an improvement in film formation. At higher temperatures (95 degrees C), fast removal of the liquid phase cannot be prevented by the addition of 1% coalescing agent. Although addition of higher amounts of coalescing agent results in an increase of particle deformation and film surface smoothness, it intensifies also the water absorption of dried films. Ageing below the MFFT does not result in a significant improvement of film formation in the presence of 1% coalescing agent. Above the MFFT, coalescing agents act more efficiently and cause an improvement in film formation. By addition of higher amounts of coalescing agent the completion of the film formation process is delayed: for example, by the addition of 15% EB, nearly 1 year of ageing at room temperature is required for an efficient result.

  12. Crystallization and preliminary X-ray diffraction studies of the glutaminyl cyclase from Carica papaya latex

    SciTech Connect

    Azarkan, Mohamed; Clantin, Bernard; Bompard, Coralie; Belrhali, Hassan; Baeyens-Volant, Danielle; Looze, Yvan; Wintjens, René

    2005-01-01

    The glutaminyl cyclase isolated from C. papaya latex has been crystallized using the hanging-drop method. Diffraction data have been collected at ESRF beamline BM14 and processed to 1.7 Å resolution. In living systems, the intramolecular cyclization of N-terminal glutamine residues is accomplished by glutaminyl cyclase enzymes (EC 2.3.2.5). While in mammals these enzymes are involved in the synthesis of hormonal and neurotransmitter peptides, the physiological role played by the corresponding plant enzymes still remains to be unravelled. Papaya glutaminyl cyclase (PQC), a 33 kDa enzyme found in the latex of the tropical tree Carica papaya, displays an exceptional resistance to chemical and thermal denaturation as well as to proteolysis. In order to elucidate its enzymatic mechanism and to gain insights into the structural determinants underlying its remarkable stability, PQC was isolated from papaya latex, purified and crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 62.82, b = 81.23, c = 108.17 Å and two molecules per asymmetric unit. Diffraction data have been collected at ESRF beamline BM14 and processed to a resolution of 1.7 Å.

  13. Survey of sulfur-containing rubber accelerator levels in latex and nitrile exam gloves.

    PubMed

    Depree, G J; Bledsoe, T A; Siegel, P D

    2005-08-01

    2-Mercaptobenzothiazole and zinc dialkyldithiocarbamates are commonly used sulfur-containing rubber vulcanization accelerators known to cause allergic contact dermatitis. Exposure to these agents occurs through clothing such as undergarments and shoes, latex medical devices and latex and nitrile gloves. A simple, inexpensive screening method for total sulfur accelerator and a high performance liquid chromatographic speciation method were developed in the present study. These methods were applied to screen and quantify the sulfur accelerator content from 38 brands of 'off-the-shelf' latex and nitrile gloves obtained from commercial vendors. It was found that accelerator levels ranged from not detectable to 7.35 mg/g in the gloves analysed. Brands were found to contain single and multiple accelerator species within the glove. Powdered gloves had significantly higher accelerator levels than powder-free gloves from the same manufacturer; however, these chemical accelerators do not preferentially partition to the powder. The present analytical methodology is suitable for both manufacturing quality validation purposes, as well as for accelerator allergy research. PMID:16033405

  14. PythonTeX: reproducible documents with LaTeX, Python, and more

    NASA Astrophysics Data System (ADS)

    Poore, Geoffrey M.

    2015-01-01

    PythonTeX is a LaTeX package that allows Python code in LaTeX documents to be executed and provides access to the output. This makes possible reproducible documents that combine results with the code required to generate them. Calculations and figures may be next to the code that created them. Since code is adjacent to its output in the document, editing may be more efficient. Since code output may be accessed programmatically in the document, copy-and-paste errors are avoided and output is always guaranteed to be in sync with the code that generated it. This paper provides an introduction to PythonTeX and an overview of major features, including performance optimizations, debugging tools, and dependency tracking. Several complete examples are presented. Finally, advanced features are summarized. Though PythonTeX was designed for Python, it may be extended to support additional languages; support for the Ruby and Julia languages is already included. PythonTeX contains a utility for converting documents into plain LaTeX, suitable for format conversion, sharing, and journal submission.

  15. Graphene encapsulated rubber latex composites with high dielectric constant, low dielectric loss and low percolation threshold.

    PubMed

    Tian, Ming; Zhang, Jing; Zhang, Liqun; Liu, Suting; Zan, Xiaoqing; Nishi, Toshio; Ning, Nanying

    2014-09-15

    A dielectric composite with high dielectric constant, low dielectric loss and low percolation threshold was prepared by using the combined strategy of encapsulating of graphene oxide nanosheets (GONS) on carboxylated nitrile rubber (XNBR) latex particles and the in situ thermal reduction in GONS at a moderate temperature. The encapsulation of GONS on XNBR latex particles was mainly realized via the hydrogen bonding interactions between GONS and XNBR during latex mixing. A segregated graphene network was obtained at a low content of thermally reduced graphene (TRG), resulting in a low percolation threshold (0.25 vol.%). The dielectric constant at 100 Hz obviously increased from 23 for pure XNBR to 2211 and 5542 for the composite with 0.5 vol.% and 0.75 vol.% of TRG, respectively. The dielectric loss of the composites retained at a low value (less than 1.5). Meanwhile, the elastic modulus only slightly increased with the presence of 0.1-0.5 vol.% of TRG, keeping the good flexibility of the dielectric composites. This study provides a simple, low-cost and effective method to prepare high performance dielectric composites, facilitating the wide application of dielectric materials.

  16. Aqueous latex/ceramic nanoparticle dispersions: colloidal stability and coating properties.

    PubMed

    Sun, Jiakuan; Velamakanni, Bhaskar V; Gerberich, William W; Francis, Lorraine F

    2004-12-15

    The effect of pH on the colloidal stability of aqueous dispersions containing antimony-doped tin oxide (ATO) or indium tin oxide (ITO) nanoparticles and poly(vinyl acetate-acrylic) copolymer (PVAc-co-acrylic) latex particles was investigated using experimental observations and Derjiaguin, Landau, Verwey and Overbeek (DLVO) theory. The microstructure, electrical properties and optical properties of composite coatings prepared from various dispersions were also studied. Zeta potential measurements revealed that the isoelectric point (IEP) of ATO nanoparticles was below pH 2.0, that of ITO nanoparticles was at pH approximately 6.0 and that of PVAc-co-acrylic latex was at pH approximately 2.0. ATO/PVAc-co-acrylic dispersions prepared at pH 3 were stable, but those prepared at pH 1.5 formed aggregates, which settled quickly with time. DLVO theory predictions are in accord with these results. Stable ITO/PVAc-co-acrylic dispersions are obtained at a pH of 3.0 and 11.0, but dispersions are not stable at a pH of 6.0, the IEP of ITO. At a pH of 3.0, DLVO results predict attraction between ITO particles and latex particles. Dispersion pH affected the microstructures and properties of ATO (or ITO)/PVAc-co-acrylic coatings. Suspensions that formed aggregates produced coatings with lower percolation thresholds and lower transparencies than those produced from stable suspensions.

  17. Biosynthesis of silver nanoparticles using latex from few Euphorbian plants and their antimicrobial potential.

    PubMed

    Patil, Satish V; Borase, Hemant P; Patil, Chandrashekhar D; Salunke, Bipinchandra K

    2012-06-01

    The synthesis of well-dispersed and ultrafine metal nanoparticles has great interest due to their distinctive physicochemical properties and biomedical applications. This study is the first report of one-step solvent-free synthesis of AgNPs using Euphorbiaceae plant latex. Among evaluated eight latex-producing plants, four (Jatropha curcas, Jatropha gossypifolia, Pedilanthus tithymaloides, and Euphorbia milii) showed high potential to produce physicochemically distinct, small-sized and bactericidal AgNPs. Phytochemical screening showed presence of rich amount of biochemicals in these plants. J. gossypifolia showed uniformly dispersed comparatively small-sized AgNPs. Dose-dependent growth inhibition of bacterial pathogens Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermis, and Micrococcus luteus was observed for J. gossypifolia latex-synthesized AgNPs with minimum inhibitory concentration values 30, 40, 70, 60, and 60 ppm, respectively, after 24 h. Possible mode of action of AgNPs against pathogens was confirmed by analyzing enzymes and cell leakage. PMID:22592777

  18. Biosynthesis of silver nanoparticles using latex from few Euphorbian plants and their antimicrobial potential.

    PubMed

    Patil, Satish V; Borase, Hemant P; Patil, Chandrashekhar D; Salunke, Bipinchandra K

    2012-06-01

    The synthesis of well-dispersed and ultrafine metal nanoparticles has great interest due to their distinctive physicochemical properties and biomedical applications. This study is the first report of one-step solvent-free synthesis of AgNPs using Euphorbiaceae plant latex. Among evaluated eight latex-producing plants, four (Jatropha curcas, Jatropha gossypifolia, Pedilanthus tithymaloides, and Euphorbia milii) showed high potential to produce physicochemically distinct, small-sized and bactericidal AgNPs. Phytochemical screening showed presence of rich amount of biochemicals in these plants. J. gossypifolia showed uniformly dispersed comparatively small-sized AgNPs. Dose-dependent growth inhibition of bacterial pathogens Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermis, and Micrococcus luteus was observed for J. gossypifolia latex-synthesized AgNPs with minimum inhibitory concentration values 30, 40, 70, 60, and 60 ppm, respectively, after 24 h. Possible mode of action of AgNPs against pathogens was confirmed by analyzing enzymes and cell leakage.

  19. Evaluation of latex agglutination and microtube coagulase tests for detection of Staphylococcus aureus.

    PubMed

    Pourshadi, M; Klaas, J

    1984-09-01

    In a blind study, a latex agglutination test (Serostat Staphylococcus, Scott Laboratories) and a microtube coagulase test (Staphase, API) were evaluated for their ability to detect Staphylococcus aureus. Of 289 isolates of catalase-positive, gram-positive cocci, 122 were identified as S. aureus based on positive reactions in at least three of the following tests: tube coagulase, slide coagulase, DNase production, or anaerobic fermentation of mannitol. The latex agglutination test gave positive reactions for all S. aureus isolates and 10 (6%) non-S. aureus isolates. The slide coagulase test was positive for 121 S. aureus isolates and three (2%) non-S. aureus isolates. The microtube coagulase test detected 53, 90, and 98% of the S. aureus isolates after 2, 4, and 24 hr, respectively. In contrast, the conventional tube coagulase test detected 97% of the S. aureus isolates after 2 hr, and 98% after 4 and 24 hr. Two isolates of S. aureus gave negative tube coagulase reactions at 37 degrees C, but positive reactions at room temperature after 24 hr. The combination of tube and slide coagulase tests provided the most reliable results. The slide and tube coagulase tests gave more reliable results than the latex agglutination and microtube coagulase tests, respectively.

  20. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    NASA Astrophysics Data System (ADS)

    Määttänen, Anni; Ihalainen, Petri; Törngren, Björn; Rosqvist, Emil; Pesonen, Markus; Peltonen, Jouko

    2016-02-01

    Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV-vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH2)11OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal (optical and electrical) real-time monitoring of length-scale-dependent biomaterial-surface interactions.

  1. Steam injection system for lunar concrete

    NASA Astrophysics Data System (ADS)

    Pakulski, Dennis M.; Knox, Kenneth J.

    Results of lunar concrete research into steam hydration of concrete currently under way at the USAF Academy by the Department of Civil Engineering are presented. The use of Design of Experiments methodologies to quantify the effects input factors to a process have on the measured responses of the process is demonstrated. The feasibility of hydrating high alumina cement concrete (mortar) using steam injection is shown; the process yields compressible strengths comparable to Portland cement concrete cast with water. The concrete strength is increased with increasing steam exposure (to a point) and with increased density of the dry cement aggregate mixture. Cure time seems to have little effect on the concrete strength.

  2. Nanogranular origin of concrete creep.

    PubMed

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.

  3. Nanogranular origin of concrete creep

    PubMed Central

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C–S–H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C–S–H forms: low density, high density, ultra-high density. We demonstrate that the creep rate (≈1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  4. SHEAR CARRYING CAPACITY OF SEGMENTAL CONCRETE BEAMS WITH DRAPED EXTERNAL TENDONS

    NASA Astrophysics Data System (ADS)

    Nguyen, Dinh Hung; Matsumoto, Koji; Watanabe, Ken; Hasegawa, Tsuyoshi; Niwa, Junichiro

    This study presents an investigation of the shear be havior of segmental concrete beams with draped external tendons. Deviator force and transfer mechanism of prestressing force from an anchorage that affect the shear failure mechanism have been examined base d on the results of experimental procedure and FEM with different location of deviator and inclined angle of draped tendons. The modified model proposed by authors has been extended for segmental concrete beam s with draped external tendons with considering the effect of deviator force and transfer mechanism of prestressing force from the anchorage. The results from the extended modified model for draped external tendons had a good agreement with experimental results.

  5. 27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, ...

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

    27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, A SHORT DISTANCE WEST OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVENUE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  6. Improving rubber concrete by waste organic sulfur compounds.

    PubMed

    Chou, Liang-Hisng; Lin, Chun-Nan; Lu, Chun-Ku; Lee, Cheng-Haw; Lee, Maw-Tien

    2010-01-01

    In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly. PMID:19710121

  7. Improving rubber concrete by waste organic sulfur compounds.

    PubMed

    Chou, Liang-Hisng; Lin, Chun-Nan; Lu, Chun-Ku; Lee, Cheng-Haw; Lee, Maw-Tien

    2010-01-01

    In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly.

  8. The use of cycloaliphatic epoxides in latex and ultraviolet-curable coatings

    NASA Astrophysics Data System (ADS)

    Nash, Heather April

    The use of more environmentally friendly coating technology continues to grow as more stringent EPA regulations demand their usage. Two types of coatings commonly employed for addressing these issues are latex and UV-curable systems. In this dissertation, the use of cycloaliphatic epoxides was investigated in both crosslinkable core-shell latex formulations as well as the major component in cationic UV-curable coatings. In order to reduce the heat required for latex synthesis, redox initiators were studied as an alternative to the thermal initiator commonly used. It was found that using such initiators gave similar properties to the latexes prepared with the thermal initiator, as well as some enhanced properties. In addition, the base used for neutralizing the carboxyl-functional latexes was studied. It was found that the base used can have an effect on particle size as well as mechanical properties. The UV-curable formulations were studied in terms of the effect of composition variables on the mechanical properties as well as on the UV-curing kinetics. The introduction of more mobile species into cycloaliphatic epoxide formulations resulted in an increase in the cure rate during UV irradiation and an enhancement in coating properties. The effect of introducing different components into the formulations was also studied in terms of cure kinetics and coatings properties. By using model alcohols and a model epoxide monomer, the UV cure rate was enhanced as the concentration of these materials was increased. The effect of post-cure treatment on the films was also investigated to determine both physical and chemical changes in the films as a function of treatment. The treatments studied included annealing, solvent treatment, and acid treatment. These treatments were found to have both physical and chemical effects on the films. In addition, the effect of post-cure humidity was evaluated for the effect on the dark cure reactions in the films. High humidity had a greater

  9. Profiling Ethylene-Responsive Genes Expressed in the Latex of the Mature Virgin Rubber Trees Using cDNA Microarray

    PubMed Central

    Nie, Zhiyi; Kang, Guijuan; Duan, Cuifang; Li, Yu; Dai, Longjun; Zeng, Rizhong

    2016-01-01

    Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2,973 unique genes (probes) was first developed and used to analyze the gene expression changes in the latex of the mature virgin rubber trees after ethephon treatment at three different time-points: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ –2 (q-value < 0.05) in ethephon-treated rubber trees compared with control trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes. The 163 ethylene-responsive genes were involved in several biological processes including organic substance metabolism, cellular metabolism, primary metabolism, biosynthetic process, cellular response to stimulus and stress. The presented data suggest that the laticifer water circulation, production and scavenging of reactive oxygen species, sugar metabolism, and assembly and depolymerization of the latex actin cytoskeleton might play important roles in ethylene-induced increase of latex production. The results may provide useful insights into understanding the molecular mechanism underlying the effect of ethylene on latex metabolism of H. brasiliensis. PMID:26985821

  10. Profiling Ethylene-Responsive Genes Expressed in the Latex of the Mature Virgin Rubber Trees Using cDNA Microarray.

    PubMed

    Nie, Zhiyi; Kang, Guijuan; Duan, Cuifang; Li, Yu; Dai, Longjun; Zeng, Rizhong

    2016-01-01

    Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2,973 unique genes (probes) was first developed and used to analyze the gene expression changes in the latex of the mature virgin rubber trees after ethephon treatment at three different time-points: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ -2 (q-value < 0.05) in ethephon-treated rubber trees compared with control trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes. The 163 ethylene-responsive genes were involved in several biological processes including organic substance metabolism, cellular metabolism, primary metabolism, biosynthetic process, cellular response to stimulus and stress. The presented data suggest that the laticifer water circulation, production and scavenging of reactive oxygen species, sugar metabolism, and assembly and depolymerization of the latex actin cytoskeleton might play important roles in ethylene-induced increase of latex production. The results may provide useful insights into understanding the molecular mechanism underlying the effect of ethylene on latex metabolism of H. brasiliensis. PMID:26985821

  11. Fatigue properties of rubber modified pavements. Final report

    SciTech Connect

    Raad, L.; Saboundjian, S.; Yuan, X.

    1995-05-01

    This report presents results of a study to determine the fatigue behavior of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements. Laboratory studies were conducted on field specimens using the flexural fatigue test in the controlled-displacement mode. Tests were performed at 72 deg F and 40 deg F. Tested materials include (1) conventional HMA with AC 2.5 and AC 5; (2) PlusRide RUMAC with AC 5; (3) asphalt-rubber concrete with AC 2.5 (wet Process); and (4) rubberized asphalt-rubber concrete with AC 2.5 (wet/dry process).

  12. Carbonation and its effects in reinforced concrete

    SciTech Connect

    Broomfield, J.P.

    2000-01-01

    Carbonation is the result of interaction of carbon dioxide (CO{sub 2}) gas in the atmosphere with the alkaline hydroxides in the concrete. CO{sub 2} diffuses through the concrete and rate of movement of the carbonation front roughly follows Fick's law of diffusion. Carbonation depth can be measured by exposing fresh concrete and spraying it with phenolphthalein indicator solution. An example of the test on a reinforced concrete mullion is given.

  13. Direct observation of pH-induced coalescence of latex-stabilized bubbles using high-speed video imaging.

    PubMed

    Ata, Seher; Davis, Elizabeth S; Dupin, Damien; Armes, Steven P; Wanless, Erica J

    2010-06-01

    The coalescence of pairs of 2 mm air bubbles grown in a dilute electrolyte solution containing a lightly cross-linked 380 nm diameter PEGMA-stabilized poly(2-vinylpyridine) (P2VP) latex was monitored using a high-speed video camera. The air bubbles were highly stable at pH 10 when coated with this latex, although coalescence could be induced by increasing the bubble volume when in contact. Conversely, coalescence was rapid when the bubbles were equilibrated at pH 2, since the latex undergoes a latex-to-microgel transition and the swollen microgel particles are no longer adsorbed at the air-water interface. Rapid coalescence was also observed for latex-coated bubbles equilibrated at pH 10 and then abruptly adjusted to pH 2. Time-dependent postrupture oscillations in the projected surface area of coalescing P2VP-coated bubble pairs were studied using a high-speed video camera in order to reinvestigate the rapid acid-induced catastrophic foam collapse previously reported [Dupin, D.; et al. J. Mater. Chem. 2008, 18, 545]. At pH 10, the P2VP latex particles adsorbed at the surface of coalescing bubbles reduce the oscillation frequency significantly. This is attributed to a close-packed latex monolayer, which increases the bubble stiffness and hence restricts surface deformation. The swollen P2VP microgel particles that are formed in acid also affected the coalescence dynamics. It was concluded that there was a high concentration of swollen microgel at the air-water interface, which created a localized, viscous surface gel layer that inhibited at least the first period of the surface area oscillation. Close comparison between latex-coated bubbles at pH 10 and those coated with 66 microm spherical glass beads indicated that the former system exhibits more elastic behavior. This was attributed to the compressibility of the latex monolayer on the bubble surface during coalescence. A comparable elastic response was observed for similar sized titania particles, suggesting

  14. Molecular Survey of Concrete Biofilm Microbial Communities

    EPA Science Inventory

    Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA g...

  15. RADON GENERATION AND TRANSPORT IN AGED CONCRETE

    EPA Science Inventory

    The report gives results of a characterization of radon generation and transport in Florida concretes sampled from 12- to 45-year-old residential slabs. It also compares measurements from old concrete samples to previous measurements on newly poured Florida residential concretes....

  16. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  17. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  18. Lightweight concrete with enhanced neutron shielding

    DOEpatents

    Brindza, Paul Daniel; Metzger, Bert Clayton

    2016-09-13

    A lightweight concrete containing polyethylene terephthalate in an amount of 20% by total volume. The concrete is enriched with hydrogen and is therefore highly effective at thermalizing neutrons. The concrete can be used independently or as a component of an advanced neutron radiation shielding system.

  19. Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

    NASA Astrophysics Data System (ADS)

    Abulfaraj, Waleed H.; Kamal, Salah M.

    1994-07-01

    The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concretes shielding. Multiattribute utility theory is selected to accommodate decision makers' preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Ilmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Ilmenite Serpentine concrete.

  20. Identification, quantification, spatiotemporal distribution and genetic variation of major latex secondary metabolites in the common dandelion (Taraxacum officinale agg.).

    PubMed

    Huber, Meret; Triebwasser-Freese, Daniella; Reichelt, Michael; Heiling, Sven; Paetz, Christian; Chandran, Jima N; Bartram, Stefan; Schneider, Bernd; Gershenzon, Jonathan; Erb, Matthias

    2015-07-01

    The secondary metabolites in the roots, leaves and flowers of the common dandelion (Taraxacum officinale agg.) have been studied in detail. However, little is known about the specific constituents of the plant's highly specialized laticifer cells. Using a combination of liquid and gas chromatography, mass spectrometry and nuclear magnetic resonance spectrometry, we identified and quantified the major secondary metabolites in the latex of different organs across different growth stages in three genotypes, and tested the activity of the metabolites against the generalist root herbivore Diabrotica balteata. We found that common dandelion latex is dominated by three classes of secondary metabolites: phenolic inositol esters (PIEs), triterpene acetates (TritAc) and the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G). Purification and absolute quantification revealed concentrations in the upper mgg(-1) range for all compound classes with up to 6% PIEs, 5% TritAc and 7% TA-G per gram latex fresh weight. Contrary to typical secondary metabolite patterns, concentrations of all three classes increased with plant age. The highest concentrations were measured in the main root. PIE profiles differed both quantitatively and qualitatively between plant genotypes, whereas TritAc and TA-G differed only quantitatively. Metabolite concentrations were positively correlated within and between the different compound classes, indicating tight biosynthetic co-regulation. Latex metabolite extracts strongly repelled D. balteata larvae, suggesting that the latex constituents are biologically active. PMID:25682510

  1. Statistical Discrimination of Latex between Healthy and White Root Infected Rubber Tree based on Dry Rubber Content

    NASA Astrophysics Data System (ADS)

    Suhaimi Sulaiman, Mohd; Hashim, Hadzli; Faiz Mohd Sampian, Ahmad; Korlina Madzhi, Nina; Faris Mohd Azmi, Azrie; Aishah Khairuzzaman, Noor; Aima Ismail, Faridatul

    2015-11-01

    Dry rubber content (DRC) is one of main material existing inside latex. It is usually in ranged of 25% - 45% of rubber latex. Statistical analysis are done to determine the discrimination of dry rubber content of latex between healthy and white root infected rubber tree. Based on 150 rubber trees and 10 clones tested, parametric test which include normality test, error-bar plot, and paired samples test are done. The result outcomes have shown that both data of dry rubber content of latex for healthy and white root infected rubber tree are normally distributed. Error-bar plot test is clearly indicated that there is visible discrimination between both cases. Paired samples test are done to reinforce this findings in terms of numerical p- value which is found to be less than 0.05. Thus, this indicate overwhelming evidence that healthy group can be discriminated from white root. Conclusively, changes in DRC content in latex can be correlated with white root disease infections of rubber tree.

  2. Comparative study on plant latex proteases and their involvement in hemostasis: a special emphasis on clot inducing and dissolving properties.

    PubMed

    Rajesh, Rajaiah; Shivaprasad, Holenarasipura V; Gowda, Chandagalu D; Nataraju, Angaswamy; Dhananjaya, Badarapura L; Vishwanath, Bannikuppe S

    2007-08-01

    In the present study we compared the clot inducing and dissolving properties of Calotropis gigantea R. Br. (Asclepiadaceae), Synadenium grantii Hook. f. (Euphorbiaceae) and Wrightia tinctoria R. Br. (Apocynaceae) latex extracts. All the three latex extracts hydrolyzed casein, fibrinogen and crude fibrin dose-dependently. The proteolytic action on fibrinogen subunity was in the order of Aalpha > Bbeta > gamma. All extracts exhibited procoagulant activity as assayed by re-calcification time. However, thrombin like activity is restricted to C. gigantea. In addition, the extracts dose-dependently hydrolyzed blood and plasma clots. Furthermore, the hydrolyzing pattern of fibrin in the plasma clot was substantiated by SDS-PAGE. The extracts hydrolyzed all the subunits (alpha polymer, alpha-chains, gamma-gamma dimer and beta-chain) of fibrin efficiently. Both fibrinogenolytic and fibrinolytic activity potency of the extracts were in the order of C. gigantea > S. grantii > W. tinctoria. Among the three latices, C. gigantea is toxic with a minimum hemorrhagic dose (MHD) of > 75 microg, whereas S. grantii and W. tinctoria latex extracts were non-toxic and did not induce any hemorrhagic effect at the tested dose (> 200 microg). The proteolytic activity of C. gigantea latex extract on different substrates was inhibited by IAA. On the other hand, the proteolytic activities of S. grantii and W. tinctoria were inhibited by PMSF. Thus, this study provides the basis for the probable action of plant latex proteases to stop bleeding and effect wound healing as exploited in folk medicine.

  3. Identification, quantification, spatiotemporal distribution and genetic variation of major latex secondary metabolites in the common dandelion (Taraxacum officinale agg.).

    PubMed

    Huber, Meret; Triebwasser-Freese, Daniella; Reichelt, Michael; Heiling, Sven; Paetz, Christian; Chandran, Jima N; Bartram, Stefan; Schneider, Bernd; Gershenzon, Jonathan; Erb, Matthias

    2015-07-01

    The secondary metabolites in the roots, leaves and flowers of the common dandelion (Taraxacum officinale agg.) have been studied in detail. However, little is known about the specific constituents of the plant's highly specialized laticifer cells. Using a combination of liquid and gas chromatography, mass spectrometry and nuclear magnetic resonance spectrometry, we identified and quantified the major secondary metabolites in the latex of different organs across different growth stages in three genotypes, and tested the activity of the metabolites against the generalist root herbivore Diabrotica balteata. We found that common dandelion latex is dominated by three classes of secondary metabolites: phenolic inositol esters (PIEs), triterpene acetates (TritAc) and the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G). Purification and absolute quantification revealed concentrations in the upper mgg(-1) range for all compound classes with up to 6% PIEs, 5% TritAc and 7% TA-G per gram latex fresh weight. Contrary to typical secondary metabolite patterns, concentrations of all three classes increased with plant age. The highest concentrations were measured in the main root. PIE profiles differed both quantitatively and qualitatively between plant genotypes, whereas TritAc and TA-G differed only quantitatively. Metabolite concentrations were positively correlated within and between the different compound classes, indicating tight biosynthetic co-regulation. Latex metabolite extracts strongly repelled D. balteata larvae, suggesting that the latex constituents are biologically active.

  4. Spermiotoxicity of commercial condoms made from polyurethane, polyisoprene and latex, using domestic ruminants as an experimental animal model.

    PubMed

    Pradiee, J; O'Brien, E; Esteso, M C; Castaño, C; Toledano-Díaz, A; López-Sebastián, A; Santiago-Moreno, J

    2016-05-01

    The use of condoms could provide a means of collecting high-quality spermatozoa from different species under physiological ejaculation conditions. However, certain condom materials may affect sperm functionality. This study examined the spermiotoxicity of different commercial condom materials towards ram and goat spermatozoa. Sperm samples were diluted in Tyrode's medium and placed in contact with a piece of condom material (polyurethane, polyisoprene or latex) and incubated for 30 or 90 min. Contact time in the polyisoprene and latex treatments affected some sperm variables; no such effects were seen, however, in the polyurethane treatments. For ram spermatozoa in contact with polyisoprene, the percentage of dead spermatozoa with a damaged acrosome increased at 90 min, while for spermatozoa in contact with latex, the percentage of live spermatozoa with an intact acrosome decreased. For goat spermatozoa in contact with both polyisoprene and latex, the percentage of dead spermatozoa with a damaged acrosome increased at 90 min, while for spermatozoa in contact with polyisoprene, the percentage of live spermatozoa with an intact acrosome decreased. In conclusion, latex and polyisoprene contain components that affect sperm motility, plasma membrane integrity and acrosome function. Polyurethane does not seem to reduce the quality of semen.

  5. Concrete Finisher Program. Apprenticeship Training.

    ERIC Educational Resources Information Center

    Alberta Learning, Edmonton. Apprenticeship and Industry Training.

    This document presents information about the apprenticeship training program of Alberta, Canada, in general and the concrete finishing program in particular. The first part of the document discusses the following items: Alberta's apprenticeship and industry training system; the apprenticeship and industry training committee structure; local…

  6. Quick-setting concrete and a method for making quick-setting concrete

    DOEpatents

    Wagh, Arun S.; Singh, Dileep; Pullockaran, Jose D.; Knox, Lerry

    1997-01-01

    A method for producing quick setting concrete is provided comprising hydrng a concrete dry mixture with carbonate solution to create a slurry, and allowing the slurry to cure. The invention also provides for a quick setting concrete having a predetermined proportion of CaCO.sub.3 of between 5 and 23 weight percent of the entire concrete mixture, and whereby the concrete has a compression strength of approximately 4,000 pounds per square inch (psi) within 24 hours after pouring.

  7. Regulation of HbPIP2;3, a Latex-Abundant Water Transporter, Is Associated with Latex Dilution and Yield in the Rubber Tree (Hevea brasiliensis Muell. Arg.)

    PubMed Central

    Cai, Xiuqing; Wang, Jin; Rookes, James; Lin, Weifu; Cahill, David; Kong, Lingxue

    2015-01-01

    Rubber tree (Hevea brasiliensis) latex, the source of natural rubber, is synthesised in the cytoplasm of laticifers. Efficient water inflow into laticifers is crucial for latex flow and production since it is the determinant of the total solid content of latex and its fluidity after tapping. As the mature laticifer vessel rings are devoid of plasmodesmata, water exchange between laticifers and surrounding cells is believed to be governed by plasma membrane intrinsic proteins (PIPs). To identify the most important PIP aquaporin in the water balance of laticifers, the transcriptional profiles of ten-latex-expressed PIPs were analysed. One of the most abundant transcripts, designated HbPIP2;3, was characterised in this study. When tested in Xenopus laevis oocytes HbPIP2;3 showed a high efficiency in increasing plasmalemma water conductance. Expression analysis indicated that the HbPIP2;3 gene was preferentially expressed in latex, and the transcripts were up-regulated by both wounding and exogenously applied Ethrel (a commonly-used ethylene releaser). Although regular tapping up-regulated the expression of HbPIP2;3 during the first few tappings of the virginal rubber trees, the transcriptional kinetics of HbPIP2;3 to Ethrel stimulation in the regularly tapped tree exhibited a similar pattern to that of the previously reported HbPIP2;1 in the virginal rubber trees. Furthermore, the mRNA level of HbPIP2;3 was associated with clonal yield potential and the Ethrel stimulation response. Together, these results have revealed the central regulatory role of HbPIP2;3 in laticifer water balance and ethylene stimulation of latex production in Hevea. PMID:25927524

  8. Involvement of HbPIP2;1 and HbTIP1;1 Aquaporins in Ethylene Stimulation of Latex Yield through Regulation of Water Exchanges between Inner Liber and Latex Cells in Hevea brasiliensis1[C][W

    PubMed Central

    Tungngoen, Kessarin; Kongsawadworakul, Panida; Viboonjun, Unchera; Katsuhara, Maki; Brunel, Nicole; Sakr, Soulaiman; Narangajavana, Jarunya; Chrestin, Hervé

    2009-01-01

    Natural rubber is synthesized in specialized articulated cells (laticifers) located in the inner liber of Hevea brasiliensis. Upon bark tapping, the laticifer cytoplasm (latex) is expelled due to liber tissue turgor pressure. In mature virgin (untapped) trees, short-term kinetic studies confirmed that ethylene, the rubber yield stimulant used worldwide, increased latex yield, with a concomitant decrease in latex total solid content, probably through water influx in the laticifers. As the mature laticifers are devoid of plasmodesmata, the rapid water exchanges with surrounding liber cells probably occur via the aquaporin pathway. Two full-length aquaporin cDNAs (HbPIP2;1 and HbTIP1;1, for plasma membrane intrinsic protein and tonoplast intrinsic protein, respectively) were cloned and characterized. The higher efficiency of HbPIP2;1 than HbTIP1;1 in increasing plasmalemma water conductance was verified in Xenopus laevis oocytes. HbPIP2;1 was insensitive to HgCl2. In situ hybridization demonstrated that HbPIP2;1 was expressed in all liber tissues in the young stem, including the laticifers. HbPIP2;1 was up-regulated in both liber tissues and laticifers, whereas HbTIP1;1 was down-regulated in liber tissues but up-regulated in laticifers in response to bark Ethrel treatment. Ethylene-induced HbPIP2;1 up-regulation was confirmed by western-blot analysis. The promoter sequences of both genes were cloned and found to harbor, among many others, ethylene-responsive and other chemical-responsive (auxin, copper, and sulfur) elements known to increase latex yield. Increase in latex yield in response to ethylene was emphasized to be linked with water circulation between the laticifers and their surrounding tissues as well as with the probable maintenance of liber tissue turgor, which together favor prolongation of latex flow. PMID:19656906

  9. Microbiologically induced deterioration of concrete - A Review

    PubMed Central

    Wei, Shiping; Jiang, Zhenglong; Liu, Hao; Zhou, Dongsheng; Sanchez-Silva, Mauricio

    2013-01-01

    Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed. PMID:24688488

  10. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    NASA Astrophysics Data System (ADS)

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-01

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (Tm) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  11. The Latex of Hevea brasiliensis Contains High Levels of Both Chitinases and Chitinases/Lysozymes 1

    PubMed Central

    Martin, Melinda N.

    1991-01-01

    The latex of the commercial rubber tree, Hevea brasiliensis, was fractionated by ultracentrifugation as described by G. F. J. Moir ([1959] Nature 184: 1626-1628) into a top layer of rubber particles, a cleared cytoplasm, and a pellet that contains primarily specialized vacuoles known as lutoids. The proteins in each fraction were resolved by two-dimensional gel electrophoresis. Both the pellet fraction and cleared cytoplasm contained large amounts of relatively few proteins, suggesting that laticifers serve a very specialized function in the plant. More than 75% of the total soluble protein in latex was found in the pellet fraction. Twenty-five percent of the protein in the pellet was identified as chitinases/lysozymes, which are capable of degrading the chitin component of fungal cell walls and the peptidoglycan component of bacterial cell walls. Both the chitinase and lysozyme activities were localized exclusively in the pellet or lutoid fraction. The chitinases/lysozymes were resolved into acidic and basic classes of proteins and further purified. An acidic protein (molecular mass 25.5 kD) represented 20% of the chitinase activity in latex; this protein lacked the low level of lysozyme activity that is associated with many plant chitinases. Six basic proteins, having both chitinase and lysozyme activities in various ratios and molecular mass of 27.5 or 26 kD, were resolved. Two of the basic proteins had very high lysozyme specific activities which were comparable to the specific activities reported for animal lysozymes. Like animal lysozymes, but unlike previously characterized plant chitinases/lysozymes, these basic chitinases/lysozymes were also capable of completely lysing or clearing suspensions of bacterial cell walls. These results suggest that laticifers may serve a defensive role in the plant. Images Figure 2 Figure 5 PMID:16668007

  12. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    SciTech Connect

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-30

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (T{sub m}) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  13. Superfund Record of Decision (EPA Region 2): Industrial Latex, Bergen County, Wallington, NJ. (First remedial action), September 1992

    SciTech Connect

    Not Available

    1992-09-30

    The 9.67-acre Industrial Latex site is a chemical adhesives and natural and synthetic rubber compounds manufacturer in Wallington, Bergen County, New Jersey. From 1951 to 1980, the Industrial Latex Corporation manufactured both chemical adhesives and natural and synthetic rubber compounds. Adhesives were initially formmulated using vegetable protein in a solvent base. The ROD addresses the final remedy for the contamination present in the soil, sediment, buildings and equipment, drums, sludge, septic system, and hardened latex, as the first of two operable units. The primary contaminants of concern affecting the soil, sediment, sludge, and debris are VOCs including PCE, TCE, toluene, and xylenes; other organics, including PAHs, PCBs, pesticides, and phenols; and metals, including arsenic and lead.

  14. Directed movement of latex particles in the gynoecia of three species of flowering plants.

    PubMed

    Sanders, L C; Lord, E M

    1989-03-24

    The secretory matrix of the stylar-transmitting tract of angiosperms has been characterized as a nutrient medium for the growth of pollen tubes, acting to guide tubes to the ovules. When nonliving particles (latex beads) were artificially introduced onto the transmitting tracts of styles of Hemerocallis flava, Raphanus raphanistrum, and Vicia faba, they were translocated to the ovary at rates similar to those of pollen tubes. Direct observations were made on the movement of individual beads along the secretory epidermis in the style and ovary of Vicia faba. The transmitting tract may play an active role in extending tube tips to their destination in the ovary. PMID:17847262

  15. Critical behavior of gelation probed by the dynamics of latex spheres

    SciTech Connect

    Fadda, G. C.; Lairez, D.; Pelta, J.

    2001-06-01

    We report a quasielastic light scattering study of the dynamics of large latex probe particles (R=225nm) in gelatin solution undergoing gelation. We show that by focusing on the short-time and long-time behavior of the autocorrelation function, it is possible to simply interpret out data in terms of the divergence of the viscosity and emergence of the shear elastic modulus near the gel point. Our crude analysis allows us to grasp the critical behavior of gelation and to obtain the two critical exponents of the transport properties.

  16. Synthesis of Carbon Nanotube and Its Potential Application in Protein Purification by Using Skim Latex Serum

    NASA Astrophysics Data System (ADS)

    Mujawar, N. M.; Yusof, F.; Alkhatib, M. F.; Muataz, A. A.; Qudsieh, I. Y.; Mohammed, A. Al Saadi; Khalid, M.

    2009-06-01

    Carbon nanotubes (CNTs) have been synthesized by a gas phase double stage chemical vapor deposition (DS-CVD) technique using acetylene (C2H2) and hydrogen (H2) as precursor gases. The morphology and the structure of CNTs were characterized using field emission scanning electron microscope (FSEM) and transmission electron microscope (TEM). The CNTs produced were purified and functionalized by using covalent functionalization methods. The functionalized CNTs were used as column chromatographic media for skim latex protein purification. In this process, pH and ionic strength were optimized to achieve higher efficiency in protein purification.

  17. Curcacycline A--a novel cyclic octapeptide isolated from the latex of Jatropha curcas L.

    PubMed

    van den Berg, A J; Horsten, S F; Kettenes-van den Bosch, J J; Kroes, B H; Beukelman, C J; Leeflang, B R; Labadie, R P

    1995-01-30

    From the latex of Jatropha curcas L. (Euphorbiaceae) a novel cyclic octapeptide was isolated, which we named curcacycline A. The compound was found to contain one threonine, one valine, two glycine, and four leucine residues. By two-dimensional 1H-NMR spectroscopy (HOHAHA and ROESY), its sequence was determined to be Gly1-Leu2-Leu3-Gly4-Thr5-Val6-Leu7-Leu8-Gly1+ ++. Curcacycline A displays a moderate inhibition of (i) classical pathway activity of human complement and (ii) proliferation of human T-cells.

  18. Aubergine and Potato Sensitivity with Latex Sensitisation and Oral Allergy Syndrome

    PubMed Central

    Bansal, A. S.

    2013-01-01

    Aubergine allergy is rare outside of India and the far east, and very few cases have been reported. We describe a case of aubergine allergy in a 9-year-old girl of Anglo-Indian descent who also had sensitivity to potato, coincidental oral allergy syndrome, and latex sensitisation with mild oral symptoms on consuming kiwi fruit. Specific IgE to aubergine was negative, but skin testing was positive to both raw and cooked aubergine. With early and increased consumption of exotic vegetables in western countries, more cases of aubergine allergy can be expected and negative blood tests do not exclude type 1 sensitivity. PMID:23956750

  19. Preparation of large-particle-size monodisperse polystyrene latexes in microgravity

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; El-Aasser, M. S.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.; Kornfeld, D. M.; Vicente, F. A.

    1982-01-01

    Three large-particle-size monodisperse latexes (3.44, 4.08, and 4.98 micron diameter) were prepared in an automated four-reactor apparatus on the third orbital mission of the 'Columbia' begun on March 22. Comparison with ground-based controls showed that the 4.98 micron-size flight sample was the more uniform; the uniformity at the other two sizes was about the same. The rates of polymerization in microgravity and on earth were the same within experimental error, demonstrating that radical-initiated vinyl addition polymerizations are unaffected by the weightless environment.

  20. Antibacterial and phytochemical studies on Calotropis gigantia (L.) R. Br. latex against selected cariogenic bacteria

    PubMed Central

    Ishnava, Kalpesh B.; Chauhan, Jenabhai B.; Garg, Akanksha A.; Thakkar, Arpit M.

    2011-01-01

    In vitro antibacterial potential of the chloroform, ethyl acetate, hexane, methanol and aqueous extracts of Calotropis gigantia (L.) R. Br. was evaluated by using five cariogenic bacteria, Actinomyces viscosus, Lactobacillus acidophilus, Lactobacillus casei, Streptococcus mitis and Streptococcus mutans. Agar well diffusion method and minimum inhibitory concentration (MIC) were used for this purpose. The chloroform extracted fraction of latex showed inhibitory effect against S. mutans and L. acidophilus with MIC value of 0.032 and 0.52 mg/mL, respectively. Qualitative investigation on structure elucidation of bioactive compound using IR, NMR and GC–MS techniques revealed the presence of methyl nonanoate, a saturated fatty acid. PMID:23961166

  1. Diffusion of Radionuclides in Concrete and Soil

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.; Parker, Kent E.; Recknagle, Kurtis P.; Clayton, Libby N.; Wood, Marcus I.

    2012-04-25

    One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability of the surrounding soil to retard radionuclide migration. The objective of our study was to measure the diffusivity of Re, Tc and I in concrete containment and the surrounding vadose zone soil. Effects of carbonation, presence of metallic iron, and fracturing of concrete and the varying moisture contents in soil on the diffusivities of Tc and I were evaluated.

  2. Development and evaluation of a recombinant-glycoprotein-based latex agglutination test for rabies virus antibody assessment.

    PubMed

    Jemima, Ebenezer Angel; Manoharan, Seeralan; Kumanan, Kathaperumal

    2014-08-01

    The measurement of neutralizing antibodies induced by the glycoprotein of rabies virus is indispensable for assessing the level of neutralizing antibodies in animals or humans. A rapid fluorescent focus inhibition test (RFFIT) has been approved by WHO and is the most widely used method to measure the virus-neutralizing antibody content in serum, but a rapid test system would be of great value to screen large numbers of serum samples. To develop and evaluate a latex agglutination test (LAT) for measuring rabies virus antibodies, a recombinant glycoprotein was expressed in an insect cell system and purified, and the protein was coated onto latex beads at concentrations of 0.1, 0.25, 0.5, 0.75, and 1 mg/ml to find out the optimal concentration for coating latex beads. It was found that 0.5 mg/ml of recombinant protein was optimal for coating latex beads, and this concentration was used to sensitize the latex beads for screening of dog serum samples. Grading of LAT results was done with standard reference serum with known antibody titers. A total of 228 serum samples were tested, out of which 145 samples were positive by both RFFIT and LAT, and the specificity was found to be 100 %. In RFFIT, 151 samples were positive, the sensitivity was found to be 96.03 %, and the accuracy/concordance was found to be 97.39 %. A rapid field test-a latex agglutination test (LAT)-was developed and evaluated for rabies virus antibody assessment using recombinant glycoprotein of rabies virus expressed in an insect cell system.

  3. Randomized, double-blind, placebo-controled clinical trial of sublingual immunotherapy in natural rubber latex allergic patients

    PubMed Central

    2011-01-01

    Background Natural rubber latex allergy is a common and unsolved health problem. Since the avoidance of exposure is very difficult, immunotherapy is strongly recommended, but before its use in patients, it is essential to prove the efficacy and safety of extracts. The aim of the present randomised, double-blind, placebo-controlled clinical trial was to assess the efficacy and tolerability of latex sublingual immunotherapy in adult patients undergoing permanent latex avoidance. Methods Twenty-eight adult latex-allergic patients (5 males and 23 females), with mean age of 39 years (range 24-57) were randomized to receive a commercial latex-sublingual immunotherapy or placebo during one year, followed by another year of open, active therapy. The following outcomes were measured at baseline and at the end of first and second year of follow-up: skin prick test, gloves-use score, conjunctival challenge test, total and specific IgE, basophil activation test, and adverse reactions monitoring. Results No significant difference in any of the efficacy in vivo variables was observed between active and placebo groups at the end of the placebo-controlled phase, nor when each group was compared with their baseline values at the end of the two year-study. An improvement in the average percentage of basophils activated was observed. During the induction phase, 4 reactions in the active group and 5 in the placebo group were recorded. During the maintenance phase, two patients dropped out due to pruritus and to acute dermatitis respectively. Conclusion Further studies are needed to evaluate latex-sublingual immunotherapy, since efficacy could not be demonstrated in adult patients with avoidance of the allergen. Trial registration number ACTRN12611000543987 PMID:21827704

  4. Thermal-hydraulic assessment of concrete storage cubicle with horizontal 3013 canisters

    SciTech Connect

    HEARD, F.J.

    1999-04-08

    The FIDAP computer code was used to perform a series of analyses to assess the thermal-hydraulic performance characteristics of the concrete plutonium storage cubicles, as modified for the horizontal placement of 3013 canisters. Four separate models were developed ranging from a full height model of the storage cubicle to a very detailed standalone model of a horizontal 3013 canister.

  5. Proportioning and performance evaluation of self-consolidating concrete

    NASA Astrophysics Data System (ADS)

    Wang, Xuhao

    A well-proportioned self-consolidating concrete (SCC) mixture can be achieved by controlling the aggregate system, paste quality, and paste quantity. The work presented in this dissertation involves an effort to study and improve particle packing of the concrete system and reduce the paste quantity while maintaining concrete quality and performance. This dissertation is composed of four papers resulting from the study: (1) Assessing Particle Packing Based Self-Consolidating Concrete Mix Design; (2) Using Paste-To-Voids Volume Ratio to Evaluate the Performance of Self-Consolidating Concrete Mixtures; (3) Image Analysis Applications on Assessing Static Stability and Flowability of Self-Consolidating Concrete, and (4) Using Ultrasonic Wave Propagation to Monitor Stiffening Process of Self-Consolidating Concrete. Tests were conducted on a large matrix of SCC mixtures that were designed for cast-in-place bridge construction. The mixtures were made with different aggregate types, sizes, and different cementitious materials. In Paper 1, a modified particle-packing based mix design method, originally proposed by Brouwers (2005), was applied to the design of self-consolidating concrete (SCC) mixs. Using this method, a large matrix of SCC mixes was designed to have a particle distribution modulus (q) ranging from 0.23 to 0.29. Fresh properties (such as flowability, passing ability, segregation resistance, yield stress, viscosity, set time and formwork pressure) and hardened properties (such as compressive strength, surface resistance, shrinkage, and air structure) of these concrete mixes were experimentally evaluated. In Paper 2, a concept that is based on paste-to-voids volume ratio (Vpaste/Vvoids) was employed to assess the performance of SCC mixtures. The relationship between excess paste theory and Vpaste/Vvoids was investigated. The workability, flow properties, compressive strength, shrinkage, and surface resistivity of SCC mixtures were determined at various ages

  6. Fracture properties of lightweight concrete

    SciTech Connect

    Chang, T.P.; Shieh, M.M.

    1996-02-01

    This study presents the experimental results of fracture properties of concrete incorporating two kinds of domestic lightweight aggregate (LWA) manufactured through either a cold-bonding or a sintering process. The cold-bonded aggregates were mainly made of pulverized fly-ash through a cold-pelletization process at ambient temperature, while the sintered aggregates were made of clay and shale expanded by heat at a temperature near 1,200 C. Experimental results show that the 28-day compressive strengths of {phi} 100 x 200 mm cylindrical concrete specimen made of those LWAs range from 30.1 (sintered) to 33.9 MPa (cold-bonded). By means of size effect law, it is found that the fracture energies, G{sub f}, were 34.42 N/m (sintered) and 37.2 N/m (cold-bonded), respectively.

  7. Radionuclide Retention in Concrete Wasteforms

    SciTech Connect

    Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

    2011-09-30

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

  8. Development of a blocking latex agglutination test for the detection of antibodies to chicken anemia virus.

    PubMed

    Trinh, Dai Quang; Ogawa, Haruko; Bui, Vuong Nghia; Nguyen, Tham Thi Hong; Gronsang, Dulyatad; Baatartsogt, Tugsbaatar; Kizito, Mugimba Kahoza; AboElkhair, Mohammed; Yamaguchi, Shigeo; Nguyen, Viet Khong; Imai, Kunitoshi

    2015-09-01

    A blocking latex agglutination test (b-LAT) developed in this study was evaluated for the detection of antibodies against chicken anemia virus (CAV) in chickens. Polystyrene latex beads were coupled with a neutralizing monoclonal antibody (mAb) to CAV (mAb-beads). When mAb-beads were mixed with antigens prepared from the lysate of MDCC-MSB1 cells infected with CAV, agglutination occurred. A short pre-incubation of CAV antigens with CAV-specific antiserum inhibited the agglutination of mAb-beads. The test results were obtained within 5min. The specificity of b-LAT was evaluated using sera from specific pathogen-free chickens and sera containing antibodies to avian influenza virus, Newcastle disease virus, infectious bursal disease virus, and Marek's disease virus; nonspecific agglutination and cross-reactivity with antibodies to unrelated viruses were not observed. The examination of 94 serum samples collected from commercial breeder chickens of various ages (17-63 weeks) revealed good agreement (93.6%, Kappa value=0.82) between b-LAT and a virus neutralization test, known to be most sensitive and specific in the detection of antibodies to CAV. These results indicate that b-LAT, a simple and rapid test, is a useful and reliable tool in CAV serology.

  9. Purification and autolysis of the ficin isoforms from fig (Ficus carica cv. Sabz) latex

    PubMed Central

    Zare, Hamid; Moosavi-Movahedi, Ali Akbar; Salami, Maryam; Mirzaei, Morteza; Saboury, Ali Akbar; Sheibani, Nader

    2013-01-01

    Ficin (EC 3.4.22.3), a cysteine endoproteolytic protease in fig trees’ latex, has multiple isoforms. Until now, no data on autolysis of individual ficins (ficin isoforms) are available. Following purification, ficins’ autolysis was determined by HPLC chromatogram changes and ultrafiltrations at different temperatures and storage times. These results showed that the number of HPLC peaks in latex proteins purification of Ficus carica cv. Sabz varied from previous fig varieties or cultivars. Proteolytic activity of ficins was inhibited by specific cysteine protease inhibitors, confirming the participation of the cysteine residue in the active site. The zeta potential of the first two eluted peaks (I and II) was negative, while that of other peaks were positive. All ficins were susceptible to autolysis when stored at high temperatures. In contrast, only the last two ficins (B, C) were prone to autolysis at cold temperature after long storage period. The rate of degradation of the ficins was significantly increased with the increased storage time. The ficin (A) related to peak (III) had the highest and the lowest surface hydrophobic patches and ratio of autolytic to proteolytic activity, respectively. PMID:23312458

  10. Chitinase and beta-1,3-glucanase in the lutoid-body fraction of Hevea latex.

    PubMed

    Subroto, T; van Koningsveld, G A; Schreuder, H A; Soedjanaatmadja, U M; Beintema, J J

    1996-09-01

    The lutoid-body (bottom) fraction of latex from the rubber tree (Hevea brasiliensis) contains a limited number of major proteins. These are, besides the chitin-binding protein hevein, its precursor and the C-terminal fragment of this precursor, proteins with enzymic activities: three hevamine components, which are basic, vacuolar, chitinases with lysozyme activity, and a beta-1,3-glucanase. Lutoid-body fractions from three rubber-tree clones differed in their contents of these enzyme proteins. The hevamine components and glucanase were isolated and several enzymic and structural properties were investigated. These enzymes are basic proteins and cause coagulation of the negatively charged rubber particles. The coagulation occurs in a rather narrow range of ratios of added protein to rubber particles, which indicates that charg neutralization is the determining factor. Differences in coagulation of rubber particles by lutoid-body fractions from various rubber clones can be explained by their content of hevamine and glucanase. Glucanase from the lutoid-body fraction may dissolve callus tissue and this may explain the observation that rubber-tree clones with a high glucanase content in this fraction produce more latex than clones with little glucanase. Sequence studies of two CNBr peptides of the glucanase indicate that this protein is homologous with glucanases from other plants, and that a C-terminal peptide, possibly involved in vacuolar targeting, may have been cleaved off. PMID:8987504

  11. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology.

  12. Structures of Two Arabidopsis thaliana Major Latex Proteins Represent Novel Helix-Grip Folds

    PubMed Central

    Lytle, Betsy L.; Song, Jikui; de la Cruz, Norberto B.; Peterson, Francis C.; Johnson, Kenneth A.; Bingman, Craig A.; Phillips, George N.; Volkman, Brian F.

    2010-01-01

    The major latex proteins (MLP) are a protein family first identified in the latex of opium poppy. They are found only in plants and have 24 identified members in Arabidopsis alone as well as in other plants such as peach, strawberry, melon, cucumber, and soybean. While the function of the MLPs is unknown, they have been associated with fruit and flower development and in pathogen defense responses. Based on modest sequence similarity, they have been characterized as members of the Bet v 1 protein superfamily; however, no structures have yet been reported. As part of an ongoing structural genomics effort, we determined the structures of two Arabidopsis thaliana MLPs: the solution structure of MLP28 (gene product of At1g70830.1) and the crystal structure of At1g24000.1. The structures revealed distinct differences when compared to one another and to the typical Bet v 1 fold. Nevertheless, NMR titration experiments demonstrated that the characteristic Bet v 1 hydrophobic binding pocket of At1g24000.1 is able to bind a ligand, suggesting that it plays a role in the function of the MLPs. A structure-based sequence analysis identified conserved hydrophobic residues in the long alpha helix that contribute to the binding cavity and may specify preferred ligands for the MLP family. PMID:19326460

  13. Rubber Elongation Factor (REF), a Major Allergen Component in Hevea brasiliensis Latex Has Amyloid Properties

    PubMed Central

    Berthelot, Karine; Lecomte, Sophie; Estevez, Yannick; Coulary-Salin, Bénédicte; Bentaleb, Ahmed; Cullin, Christophe; Deffieux, Alain; Peruch, Frédéric

    2012-01-01

    REF (Hevb1) and SRPP (Hevb3) are two major components of Hevea brasiliensis latex, well known for their allergenic properties. They are obviously taking part in the biosynthesis of natural rubber, but their exact function is still unclear. They could be involved in defense/stress mechanisms after tapping or directly acting on the isoprenoid biosynthetic pathway. The structure of these two proteins is still not described. In this work, it was discovered that REF has amyloid properties, contrary to SRPP. We investigated their structure by CD, TEM, ATR-FTIR and WAXS and neatly showed the presence of β-sheet organized aggregates for REF, whereas SRPP mainly fold as a helical protein. Both proteins are highly hydrophobic but differ in their interaction with lipid monolayers used to mimic the monomembrane surrounding the rubber particles. Ellipsometry experiments showed that REF seems to penetrate deeply into the monolayer and SRPP only binds to the lipid surface. These results could therefore clarify the role of these two paralogous proteins in latex production, either in the coagulation of natural rubber or in stress-related responses. To our knowledge, this is the first report of an amyloid formed from a plant protein. This suggests also the presence of functional amyloid in the plant kingdom. PMID:23133547

  14. Analysis of phagosomal proteomes: From latex-bead to bacterial phagosomes

    PubMed Central

    Li, Qingbo; Jagannath, Chinnaswamy; Rao, Prahlad K.; Singh, Christopher R.; Lostumbo, Giovanni

    2014-01-01

    Phagosomal proteome characterization has contributed significantly to the understanding of host–pathogen interaction and the mechanism of infectious diseases caused by intracellular bacteria. The latex bead-containing phagosome has been widely used as a model system to study phagosomal proteomes at a global level. In contrast, the study of bacteria-containing phagosomes at a similar level has just begun. A number of intracellular microbial species are studied for their proteomes during the invasion of a host, providing insight into their metabolic adaptation in host cells and interaction with host-cell antimicrobial environments. In this review, we attempt to summarize the most recent advancements in the proteomic study of microbial phagosomes, especially those originating from mouse or human cells. We also briefly describe the proteomics of latex bead-containing phagosomes because they are often used as model phagosomes for study. We provide descriptions on major biological and technological components in phagosomal proteome studies. We also discuss the role of phagosomal proteome study in the broader horizon of systems biology and the technological challenges in phagosomal proteome characterization. PMID:21080496

  15. Rubber elongation factor (REF), a major allergen component in Hevea brasiliensis latex has amyloid properties.

    PubMed

    Berthelot, Karine; Lecomte, Sophie; Estevez, Yannick; Coulary-Salin, Bénédicte; Bentaleb, Ahmed; Cullin, Christophe; Deffieux, Alain; Peruch, Frédéric

    2012-01-01

    REF (Hevb1) and SRPP (Hevb3) are two major components of Hevea brasiliensis latex, well known for their allergenic properties. They are obviously taking part in the biosynthesis of natural rubber, but their exact function is still unclear. They could be involved in defense/stress mechanisms after tapping or directly acting on the isoprenoid biosynthetic pathway. The structure of these two proteins is still not described. In this work, it was discovered that REF has amyloid properties, contrary to SRPP. We investigated their structure by CD, TEM, ATR-FTIR and WAXS and neatly showed the presence of β-sheet organized aggregates for REF, whereas SRPP mainly fold as a helical protein. Both proteins are highly hydrophobic but differ in their interaction with lipid monolayers used to mimic the monomembrane surrounding the rubber particles. Ellipsometry experiments showed that REF seems to penetrate deeply into the monolayer and SRPP only binds to the lipid surface. These results could therefore clarify the role of these two paralogous proteins in latex production, either in the coagulation of natural rubber or in stress-related responses. To our knowledge, this is the first report of an amyloid formed from a plant protein. This suggests also the presence of functional amyloid in the plant kingdom.

  16. Ineffectiveness of latex condoms in preventing contamination of the transvaginal ultrasound transducer head.

    PubMed

    Storment, J M; Monga, M; Blanco, J D

    1997-02-01

    The efficacy of condoms in preventing contamination of the transvaginal ultrasound transducer head and possible transmission of blood-borne pathogens is unknown. Our objective was to determine the rate of contamination of the transvaginal ultrasound probe after use in the emergency department. After indicated transvaginal ultrasound scans, the latex condom was removed and the transducer head was inspected for contamination. The presence of vaginal bleeding and the duration of the ultrasound scan were noted. Ten milliliters of hydrogen peroxide (H2O2) was placed in the condom. Bubbling, which occurs in the presence of blood or cervicovaginal secretions, was considered a positive test. Exposure of a clean condom or coupling gel to H2O2 did not cause bubbling. Two-tailed Fisher's Exact and Student's t tests were used for statistical analysis. Of 173 cases, 8 (5%) had a positive H2O2 test for contamination. In only 3 of these 8 cases was gross contamination seen. Latex condoms are ineffective in preventing contamination of the transvaginal ultrasound transducer head. Visual inspection of the transducer head often fails to identify the presence of blood or body fluids. This suggests that additional measures should be taken to prevent transmission of blood-borne pathogens.

  17. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology. PMID:26070188

  18. Oxygen diffusion into multiwalled carbon nanotube doped polystrene latex films using fluorescence technique.

    PubMed

    Yargı, Onder; Uğur, Saziye; Pekcan, Onder

    2013-05-01

    This study examines the oxygen diffusion into polystyrene (PS) latex/multiwalled carbon nanotube (MWNT) nanocomposite films (PS/MWNT) consisting of various amounts of MWNT via steady state fluorescence technique (SSF). PS/MWNT films were prepared from the mixture of MWNT and pyrene (P)-labeled PS latexes at various compositions at room temperature. These films were then annealed at 170 °C above glass transition (Tg) temperature of PS. Fluorescence quenching measurements were performed for each film separately to evaluate the effect of MWNT content on oxygen diffusion. The Stern-Volmer equation for fluorescence quenching is combined with Fick's law for diffusion to derive the mathematical expressions. Diffusion coefficients (D) were produced and found to be increased from 1.1 × 10(-12) to 41 × 10(-12) cm(2)s(-1) with increasing MWNT content. This increase was explained via the existence of large amounts of pores in composite films which facilitate oxygen penetration into the structure. PMID:23334487

  19. Outcome of Occupational Latex Allergy—Work Ability and Quality of Life

    PubMed Central

    Nienhaus, Albert; Kromark, Kathrin; Raulf-Heimsoth, Monika; van Kampen, Vera; Merget, Rolf

    2008-01-01

    Objective The quality of life (QOL) and work ability of health care workers allergic to natural rubber latex (NRL) were assessed after implementation of regulations on powder-free NRL gloves in Germany. Methods 196 HCW with reported NRL allergy answered a questionnaire (response rate 58%) containing the Work Ability Index (WAI), Mini Asthma Quality of Life Questionnaire (MiniAQLQ), and Dermatology Life Quality Index (DLQI). Results 63.2% still had NRL-related symptoms during the last 6 month. However on a scale from 0 to 10, the intensity of NRL-related symptoms decreased from 8.5 before to 2.3 after implementation of regulations on powder-free NRL gloves. A higher number of subjects were able to avoid NRL in the private than in the work environment (85% vs. 61%). NRL-related symptoms decreased and WAI increased with successful avoidance of NRL at workplace (b = 0.23, p = 0.003). QOL was only little affected by NRL allergy (mean: MiniAQLQ = 6.0; DLQI = 4.1). Conclusions Although there was improvement after implementation of powder-free NRL gloves, there is still a considerable number of HCW with NRL-related symptoms. Further investigations on latex avoidance and the cause of persisiting allergic symptoms in HCW with NRL allergy are therefore needed. PMID:18941629

  20. Enhancing graphene oxide reinforcing potential in composites by combined latex compounding and spray drying

    NASA Astrophysics Data System (ADS)

    Mao, Yingyan; Zhang, Shubai; Zhang, Dandan; Chan, Tung W.; Liu, Li

    2014-04-01

    A new strategy was developed to prepare graphene oxide/styrene-butadiene rubber (GO/SBR) composites with highly exfoliated GO sheets and strong interfaces. In particular, GO/SBR microparticles, in which exfoliated GO sheets (with a thickness of ˜1 nm and diameter of tens of nanometers) are trapped in a well-dispersed state throughout the SBR matrix, were made by a combined latex-compounding and spray-drying method. Subsequently, a chemical bridge between GO and rubber matrix through KH550 and Si69 was built during vulcanization, and the interfacial strength of the cured GO/SBR composite was remarkably improved. Due to the highly exfoliated structure and the strong interface, the GO/SBR composite exhibited 7.8 times higher modulus at 300% strain and 6.4 times higher tensile strength compared with cured pure SBR. The combined latex-compounding and spray-drying method presented here is feasible and water-mediated and has great potential for industrial applications.

  1. An In-vitro Comparison of Force Loss of Orthodontic Non-Latex Elastics

    PubMed Central

    Alavi, Shiva; Tabatabaie, Atusa Rahnama; Hajizadeh, Fatemeh; Ardekani, Alireza Haerian

    2014-01-01

    Objective: The amount and consistency of the applied forces to the tooth are important factors in tooth movements; therefore, the aim of this study was to compare the initial force and the force loss of three brands of elastics in 24 hours. Materials and Methods: In this in-vitro study sixty non-latex elastics (3/16 medium) from three companies (Forestadent, Dentaurum and Ortho Technology) were randomly selected. Two static tests were performed, the first in a dry environment to evaluate the initial force and the other performed in a wet environment (artificial saliva) to evaluate the force loss in 24 hours. The Universal testing machine measured the forces after stretching the elastics to three times the lumen diameter. Data were analyzed by repeated measures ANOVA, One-way ANOVA, Tukey-HSD, Paired samples test, and one sample test. Results: The difference between the brands was significant (p=0.002). Force loss was observed in all samples; 4–7.5% force loss occurred after one hour and 19–38% force loss occurred after 24 hours. The average initial force of Forestadent and Ortho Technology was significantly higher than marketed forces (p<0.001), but the initial force of Dentaurum elastics was similar to the marketed force. Conclusion: The force loss over 24 hours time period was Forestadent>Dentaurum>Ortho-Technology. According to the initial force and force loss percentage it is suggested to replace the non-latex elastics several times a day. PMID:24910671

  2. Trypsin inactivation by latex fabricated gold nanoparticles: A new strategy towards insect control.

    PubMed

    Patil, Chandrashekhar D; Borase, Hemant P; Suryawanshi, Rahul K; Patil, Satish V

    2016-10-01

    Before applying nanotechnologies in biomedical and environmental areas it is advised to study interactions of nanoparticles and other nanomaterials with biomacromolecule present in living system. Moreover there is scarcity of reports on interactions between nanoparticles and biomaterials. In present report a rapid, ecofriendly method of fabricating stable gold nanoparticles (AuNPs) using latex of Jatropha curcas is reported for the first time. AuNPs found to have characteristic absorption maxima centered at 540nm, multiple irregular shapes with size range from 20 to 50nm and have crystalline nature. Latex fabricated AuNPs were found to inhibit catalytic potential of trypsin (a vital enzyme responsible for digestion, insecticide resistance and in several disease conditions). The interactions between AuNPs and trypsin were analyzed by UV-vis spectrophotometry and microwave plasma-atomic emission spectrometry which suggests formation of trypsin-AuNPs complex responsible for lowering catalytic activity of trypsin. Transmission electron microscopy, Fourier transform infrared spectroscopy and particle size distribution studies further confirm complex formation between trypsin and AuNPs. Diverse interactions of metal nanoparticles with proteins such as covalent interaction, electrostatic interactions and binding to SH group of amino acid may be the reasons behind inhibition of trypsin activity. In vivo studies on serum of several vectors and agriculturally important pests supported instrumental results on AuNPs induced trypsin inhibition. This work will bring a new research direction to explore eco-friendly nanoparticle in insect control via inhibition of enzyme catalytic potential.

  3. Migration of BTEX and phthalates from natural rubber latex balloons obtained from the Sri Lankan market.

    PubMed

    Jayawardena, Imanda; Godakumbura, Pahan I; Prashantha, M A B

    2016-01-01

    The current study evaluates the migration of benzene, toluene, ethylbenzene, xylene (BTEX) and phthalates into artificial saliva from natural rubber latex (NRL) balloons available for sale in Sri Lanka. It was discovered that at least one BTEX compound migrated from almost all the brands. The migration of four phthalates; diethyl phthalate, dibutyl phthalate, di-isobutyl phthalate and butyl benzyl phthalate were also observed. Migratory levels of BTEX and phthalates in most of the balloon brands were above the permissible levels set by the European Union. Assessment of factors affecting the migratory levels indicated migration under active mouthing conditions and migration from the neck region of the balloons were significantly higher. The migratory levels were observed to decrease with storage time, and in certain brands the BTEX levels decreased below the permissible level. One-way ANOVA indicated no significant differences (p ≥ 0.05) in migratory levels of each individual compound within the same brand for both BTEX and phthalates. When compared among different brands, BTEX levels indicated significant differences (p ≤ 0.05), while phthalate levels were observed to not be significantly different (p ≥ 0.05). A significant difference was also observed (p ≤ 0.05) among the migratory levels of compounds under each test condition evaluated as factors affecting the migratory level. Furthermore, the solvent based colorants added to color the latex were found to be the source of BTEX and phthalates in the NRL balloons.

  4. Removal of latex glove contaminants prior to taking poly (vinylsiloxane) impressions.

    PubMed

    Browning, G C; Bromme, J C; Murchison, D F

    1994-11-01

    Sulfur compounds found in latex gloves may be deposited on teeth and gingiva, inhibiting the setting of poly(vinylsiloxane) impression materials. The objective of this in vivo study was to screen a variety of methods to remove these contaminants. Ten patients were each tested with eight decontamination methods. Before each trial, the facial surfaces and adjacent gingiva of the maxillary central and lateral incisors were contaminated with 20 wipes of a latex glove. Decontamination methods included a 30-second rinse with mouthwash, 3% hydrogen peroxide, or air-water syringe; a 30-second toothbrush scrub with water, mouthwash, or hydrogen peroxide; a 30-second cotton pellet-Cavidry scrub; and a 30-second cleaning with a prophy cup and pumice. A 10-second water rinse followed each method except the air-water syringe and Cavidry groups. A low-viscosity poly(vinylsiloxane) impression material was then used to take an impression of the area. To test surface inhibition, the gingival, tooth, and palatal impression surfaces were wiped with cotton-tipped applicators, and the degree of inhibition was subjectively categorized by two independent investigators. Mechanical decontamination with a toothbrush or pumice was significantly more effective than was rinsing alone, regardless of the solution used.

  5. Preparation of magnetic rubber with high mechanical properties by latex compounding method

    NASA Astrophysics Data System (ADS)

    Hou, Chunlin; Gao, Li; Yu, Hailing; Sun, Youyi; Yao, Junru; Zhao, Guizhe; Liu, Yaqing

    2016-06-01

    the magnetic rubber based on Fe3O4 nanoparticles and nature rubber were prepared by latex compounding method, in which stable Fe3O4 aqueous solutions were mixed with natural rubber latex and additives. This process was fast, versatile, reliable, safe, environmentally friendly and inexpensive. What's more, it was found that the magnetic and mechanical properties of magnetic rubber increased together with increase in doping content of Fe3O4 nanoparticles. Especially, it was demonstrated that the tensile strength (25.0 Mpa) of magnetic rubber was improved to be 478.0% comparing to neat natural rubber (5.2 Mpa), which was 5 times higher than maximal value reported in previous work. At the same time, the magnetic rubber revealed better thermal stability and solvent resistance comparing to the neat natural rubber, too. The work dose not only provides a new way to environmentally friendly preparation of magnetic rubber at low temperature, but also improve the mechanical and magnetic properties of magnetic rubber applied in industry.

  6. Trypsin inactivation by latex fabricated gold nanoparticles: A new strategy towards insect control.

    PubMed

    Patil, Chandrashekhar D; Borase, Hemant P; Suryawanshi, Rahul K; Patil, Satish V

    2016-10-01

    Before applying nanotechnologies in biomedical and environmental areas it is advised to study interactions of nanoparticles and other nanomaterials with biomacromolecule present in living system. Moreover there is scarcity of reports on interactions between nanoparticles and biomaterials. In present report a rapid, ecofriendly method of fabricating stable gold nanoparticles (AuNPs) using latex of Jatropha curcas is reported for the first time. AuNPs found to have characteristic absorption maxima centered at 540nm, multiple irregular shapes with size range from 20 to 50nm and have crystalline nature. Latex fabricated AuNPs were found to inhibit catalytic potential of trypsin (a vital enzyme responsible for digestion, insecticide resistance and in several disease conditions). The interactions between AuNPs and trypsin were analyzed by UV-vis spectrophotometry and microwave plasma-atomic emission spectrometry which suggests formation of trypsin-AuNPs complex responsible for lowering catalytic activity of trypsin. Transmission electron microscopy, Fourier transform infrared spectroscopy and particle size distribution studies further confirm complex formation between trypsin and AuNPs. Diverse interactions of metal nanoparticles with proteins such as covalent interaction, electrostatic interactions and binding to SH group of amino acid may be the reasons behind inhibition of trypsin activity. In vivo studies on serum of several vectors and agriculturally important pests supported instrumental results on AuNPs induced trypsin inhibition. This work will bring a new research direction to explore eco-friendly nanoparticle in insect control via inhibition of enzyme catalytic potential. PMID:27542740

  7. Equations for nonbonded concrete overlays

    NASA Astrophysics Data System (ADS)

    Chou, Y. T.

    1985-09-01

    The nature of the design equations for the nonbonded concrete overlays currently used by the US Army Corps of Engineers was examined and the original source of the equation was also examined. Using simple mechanics, new overlay equations were developed which are suitable for different thicknesses and elastic properties in the overlay and base concrete slabs. The difference in the computed overlay thickness between the new and existing equations is not large when the overlay thickness is equal to or greater than the base slab. The difference can become excessive when the overlay thickness is much less than that of the base slab. The new equations were compared with the finite element computer program for concrete overlays with various combinations of slab thickness, elastic property, and subgrade modulus. The comparisons were very favorable, indicating that the overlay equations developed in this report are analytically correct. It was difficult to judge whether the new equations are superior to the existing equation. This conclusion was expected because for all the seven test sections analyzed, the overlay thicknesses were either equal to or greater than those of the base slabs.

  8. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  9. The use of waste materials in asphalt concrete mixtures.

    PubMed

    Tuncan, Mustafa; Tuncan, Ahmet; Cetin, Altan

    2003-04-01

    The purpose of this study was to investigate (a) the effects of rubber and plastic concentrations and rubber particle sizes on properties of asphalt cement, (b) on properties of asphalt concrete specimens and (c) the effects of fly ash, marble powder, rubber powder and petroleum contaminated soil as filler materials instead of stone powder in the asphalt concrete specimens. One type of limestone aggregate and one penetration-graded asphalt cement (75-100) were used. Three concentrations of rubber and plastic (i.e. 5%, 10% and 20% of the total weight of asphalt cement), three rubber particle sizes (i.e. No. 4 [4.75mm] - 20 [0.85 mm], No. 20 [0.85mm] - 200 [0.075mm] and No. 4 [4.75mm] - 200 [0.075mm]) and one plastic particle size (i.e. No. 4 [4.75mm] - 10 [2.00mm]) were also used. It was found that while the addition of plastic significantly increased the strength of specimens, the addition of rubber decreased it. No. 4 [4.75mm] - 200 [0.075mm] rubber particles showed the best results with respect to the indirect tensile test. The Marshall stability and indirect tensile strength properties of plastic modified specimens increased. Marble powder and fly ash could be used as filler materials instead of stone powder in the asphalt concrete pavement specimens.

  10. Evaluation of a stack: A concrete chimney with brick liner

    SciTech Connect

    Joshi, J.R.; Amin, J.A.; Porthouse, R.A.

    1995-12-31

    A 200 ft. tall stack, consisting of a concrete chimney with an independent acid proof brick liner built in the 1950`s, serving the Separations facility at the Savannah River Site (SRS), was evaluated for the performance category 3 (PC3) level of Natural Phenomena Hazards (NPH) effects. The inelastic energy absorption capacity of the concrete chimney was considered in the evaluation of the earthquake resistance, in particular, to compute the F{sub {mu}} factor. The calculated value of F{sub {mu}} exceeded 3.0, while the seismic demand for the PC3 level, using an F{sub {mu}} value of 1.5, was found to be less than the capacity of the concrete chimney. The capacity formulation of ACI 307 was modified to incorporate the effect of an after design opening on the tension side. There are considerable uncertainties in determining the earthquake resistance of the independent brick liner. The critical liner section, located at the bottom of the breeching opening, does not meet the current recommendations. A discussion is provided for the possible acceptable values for the ``Moment Reduction Factor``, R{sub w} or F{sub {mu}} for the liner. Comments are provided on the comparison of stack demands using response spectra (RS) versus time history (TH) analysis, with and without soil structure interaction (SSI) effects.

  11. Concrete Cleaning, Inc. centrifugal shot blaster: Baseline report

    SciTech Connect

    1997-07-31

    The centrifugal shot blaster technology was tested and is being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The centrifugal shot blaster is an electronically operated shot blast machine that has been modified to remove layers of concrete to varying depths. A hardened steel shot propelled at a high rate of speed abrades the surface of the concrete. The depth of material removed is determined by the rate of speed the machine is traveling and the volume of shot being fired into the blast chamber. The steel shot is recycled and used over until it is pulverized into dust, which ends up in the waste container with the concrete being removed. Debris is continually vacuumed by a large dust collection system attached to the shot blaster. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  12. Concrete Cleaning, Inc. centrifugal shot blaster: Baseline report; Greenbook (chapter)

    SciTech Connect

    1997-07-31

    The centrifugal shot blaster technology was tested and is being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The centrifugal shot blaster is an electronically operated shot blast machine that has been modified to remove layers of concrete to varying depths. A hardened steel shot propelled at a high rate of speed abrades the surface of the concrete. The depth of material removed is determined by the rate of speed the machine is traveling and the volume of shot being fired into the blast chamber. The steel shot is recycled and used over until it is pulverized into dust, which ends up in the waste container with the concrete being removed. Debris is continually vacuumed by a large dust collection system attached to the shot blaster. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  13. The spectra of stimulated concentration scattering (Mie scattering) on nanoparticles latex suspension in the presence of convection

    NASA Astrophysics Data System (ADS)

    Burkhanov, I. S.; Krivokhizha, S. V.; Chaikov, L. L.

    2016-09-01

    Spectral shifts of the stimulated concentration light scattering (SCLS, stimulated Mie scattering) in suspensions of various sized latex nanoparticles in water were measured by the light guide scheme in conditions of the backscattering in the presence of convection. It is shown that the spectral shift can be either negative or positive depending on the particle size.

  14. [Latex allergy--not only a threatening danger to patients. A case report from an anesthesiological department].

    PubMed

    Konrad, C; Schüpfer, G; Fieber, T; Gerber, H

    1996-04-01

    A 31-old male nurse of anesthesiology was exposed to rubber gloves over a period of ten years. An atopic diathesis was known. From time to time he had episodes of pollinosis. Since nine months he had suffered from conjunctivitis, rhinitis and shortness of breath while wearing latex gloves. During a night shift ten minutes after consumption of tropical fruit (bananas, kiwi) he had to care for a patient in the emergency room. He wore rubber gloves and had to clean the emergency room. Initially, his palms and feet itched. Then he experienced angor and increased perspiration 90 seconds later he suffered severe dyspnea and dysesthesia in the lower extremities. Treatment with theophylline and beta sympathomimetics, steroids and antihistaminics was successful. This male nurse had a positive history for contact urticaria after exposition to rubber. He suffered a dramatic exacerbation when wearing latex gloves and inhaling latex-contaminated air after eating tropical fruits. Fruit could have been a potent booster. Hospital employees with a history of atopic disease should be screened for potential latex allergy before occupational exposure.

  15. Comparative study on the technological properties of latex and natural rubber from Hancornia speciosa Gomes and Hevea brasiliensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work reports a systematic comparative study of the properties of natural lattices and rubbers extracted from Hancornia speciosa Gomes and Hevea brasiliensis [(Willd. ex Adr. de Juss.) Muell.-Arg.] (clone RRIM 600) trees from 11 collections in Brazil throughout 2004. Natural rubber latex particl...

  16. Banyan latex: a facile fuel for the multifunctional properties of MgO nanoparticles prepared via auto ignited combustion route

    NASA Astrophysics Data System (ADS)

    Kumar, M. R. Anil; Nagaswarupa, H. P.; Anantharaju, K. S.; Gurushantha, K.; Pratapkumar, C.; Prashantha, S. C.; Shashishekar, T. R.; Nagabhushana, H.; Sharma, S. C.; Vidya, Y. S.; Daruka Prasad, B.; Vivek Babu, C. S.; Vishnu Mahesh, K. R.

    2015-09-01

    MgO nanoparticles (MNPs) were prepared by a solution combustion route using banyan tree (BT) latex and glycine as fuels. The powder x-ray diffraction results indicate the formation of a single cubic phase and the crystallite size obtained from transmission electron microscopy was found to be ˜10-15 nm. Scanning electron microscopy result reveals spherical-shaped particles obtained with BT latex. However, in a chemical route, porous and agglomerated particles were obtained. The energy band gap of MNPs obtained using BT latex and a chemical route were found to be in the range 4.85-5.0 eV. Photoluminescence peaks observed at 473, 514, and 588 nm when excited at 433 nm, which were attributed to surface defects. The enhanced photocatalytic activities of spherical MgO were due to smaller crystallite size, higher surface defects, dye sensitization, and capability to reduce the electron-hole pair recombination. Further, green-synthesized MNPs exhibit superior antifungal activity against various plant pathogens. The present studies demonstrated a green engineering route for the synthesis of multifunctional MNPs using BT latex.

  17. Using Latex Balls and Acrylic Resin Plates to Investigate the Stacking Arrangement and Packing Efficiency of Metal Crystals

    ERIC Educational Resources Information Center

    Ohashi, Atsushi

    2015-01-01

    A high-school third-year or undergraduate first-semester general chemistry laboratory experiment introducing simple-cubic, face-centered cubic, body-centered cubic, and hexagonal closest packing unit cells is presented. Latex balls and acrylic resin plates are employed to make each atomic arrangement. The volume of the vacant space in each cell is…

  18. [Latex allergy--not only a threatening danger to patients. A case report from an anesthesiological department].

    PubMed

    Konrad, C; Schüpfer, G; Fieber, T; Gerber, H

    1996-04-01

    A 31-old male nurse of anesthesiology was exposed to rubber gloves over a period of ten years. An atopic diathesis was known. From time to time he had episodes of pollinosis. Since nine months he had suffered from conjunctivitis, rhinitis and shortness of breath while wearing latex gloves. During a night shift ten minutes after consumption of tropical fruit (bananas, kiwi) he had to care for a patient in the emergency room. He wore rubber gloves and had to clean the emergency room. Initially, his palms and feet itched. Then he experienced angor and increased perspiration 90 seconds later he suffered severe dyspnea and dysesthesia in the lower extremities. Treatment with theophylline and beta sympathomimetics, steroids and antihistaminics was successful. This male nurse had a positive history for contact urticaria after exposition to rubber. He suffered a dramatic exacerbation when wearing latex gloves and inhaling latex-contaminated air after eating tropical fruits. Fruit could have been a potent booster. Hospital employees with a history of atopic disease should be screened for potential latex allergy before occupational exposure. PMID:8657987

  19. VOLATILE ORGANIC COMPOUND EMISSIONS FROM LATEX PAINT-PART 2. TEST HOUSE STUDIES AND INDOOR AIR QUALITY (IAQ) MODELING

    EPA Science Inventory

    Emission models developed using small chamber data were combined with an Indoor Air Quality (IAQ) model to analyze the impact of volatile organic compound (VOC) emissions from latex paint on indoor environments. Test house experiments were conducted to verify the IAQ model's pred...

  20. Antiedematogenic and antioxidant properties of high molecular weight protein sub-fraction of Calotropis procera latex in rat

    PubMed Central

    Chaudhary, Priyanka; de Araújo Viana, Carolina; Ramos, Marcio V.; Kumar, Vijay L.

    2015-01-01

    Objectives: The aim was to evaluate the effect of high molecular weight protein fraction of Calotropis procera latex on edema formation and oxidative stress in carrageenan-induced paw inflammation. Methods: A sub-plantar injection of carrageenan was given to induce edema in the hind paw of the rat. The inhibitory effect of high molecular weight protein fraction of C. procera latex was evaluated following intravenous administration (5 and 25 mg/kg body weight) and was compared with that of diclofenac given orally (5 mg/kg). The levels of reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and myeloperoxidase (MPO) were measured in the inflamed paw tissue at the end of the study. Results: The high molecular weight protein fraction obtained from the latex of C. procera produced a dose-dependent inhibition of edema formation that was accompanied by normalization of levels of oxidative stress markers (GSH and TBARS) and MPO, a marker for neutrophils in the paw tissue. Conclusions: The high molecular weight protein fraction of C. procera latex ameliorates acute inflammation in the paw through its antioxidant effect. PMID:25767367