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Sample records for latex modified concrete

  1. Durability of styrene-butadiene latex modified concrete

    SciTech Connect

    Shaker, F.A.; El-Dieb, A.S.; Reda, M.M.

    1997-05-01

    The durability of reinforced concrete structures represents a major concern to many investigators. The use of latex modified concrete (LMC) in construction has urged researchers to review and investigate its different properties. This study is part of a comprehensive investigation carried on the use of polymers in concrete. The main objective of this study to investigate and evaluate the main durability aspects of Styrene-Butadiene latex modified concrete (LMC) compared to those of conventional concrete. Also, the main microstructural characteristics of LMC were studied using a Scanning Electron Microscope (SEM). The SEM investigation of the LMC showed major differences in its microstructure compared to that of the conventional concrete. The LMC proved to be superior in its durability compared to the durability of conventional concrete especially its water tightness (measured by water penetration, absorption, and sorptivity tests), abrasion, corrosion, and sulphate resistance.

  2. 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.

  3. Effect of rapid set binder on early strength and permeability of HES latex modified road repair pre-packed concrete

    NASA Astrophysics Data System (ADS)

    Han, J. W.; Lee, S. K.; Yu, C.; Park, C. G.

    2015-12-01

    The early strength development characteristics and permeability resistance of high early strength (HES) pre-packed road repair concrete incorporating a rapid-set binder material were evaluated for emergency repairs to road pavement. The rapid-set binder is a mixture of rapid-set cement and silica sands whose fluidity improves with the addition of styrene butadiene latex (latex). The resulting mixture has a compressive strength of 21 MPa or higher and a flexural strength of greater than 3.5 MPa after 4 hours, the maximum curing age allowed for emergency repair materials. This study examines the strength development properties and permeability resistance of HES latex-modified pre-packed road repair concrete using a rapid- set binder as a function of the latex-to-binder mixing ratio at values of 0.40, 0.33, 0.29 and 0.25. Both early strength development properties and permeability resistance increased as the ratio of latex to rapid-set binder decreased. The mixture showed a compressive strength of 21 MPa or higher after 4 hours, which is the design standard of emergency repair concrete, only when this ratio was 0.29 or lower. A flexural strength of 3.5 MPa or greater was observed after hours only when this ratio was 0.33 or lower. The standard for permeability resistance, less than 2,000 C of chloride after 7 days of curing, was satisfied by all ratios. The ratio of latex to rapid-set binder satisfying all of the conditions for an emergency road repair material was 0.29 or less.

  4. Early age performance of latex-modified concrete bridge deck overlays

    NASA Astrophysics Data System (ADS)

    Sujjavanich, Suvimol

    Environmental factors and physical properties of latex modified concrete (LMC) are hypothesized to contribute to early age cracking in bridge deck overlays. Cracking permits the ingress of moisture and aggressive solutions into the substrate and may contribute to other subsequent distresses. Understanding the material properties and mechanisms involved is necessary to minimize these distresses. This research consisted of a two part study: first, the development of LMC strength and fracture properties at ages ranging from 5 hours to 28 days was studied, and secondly, the effects of the environment on LMC distresses were modelled. Environmental conditions: temperature, solar energy, and wind speed were determined from weather records. A fracture mechanics based model, the Fictitious Crack Model (FCM), incorporating finite element analyses and superposition techniques was employed with material properties from the first part of study on LMC performance. Different bilinear strain softening diagrams were used to predict fracture performance at different ages. The predictions agreed well with the test data. The impacts of temperature differentials on crack development were studied. The shrinkage effect was also indirectly incorporated through the temperature analysis. The material properties study indicated significant changes in strength, deformability and fracture properties, particularly during the early age. The developments differ slightly from conventional concrete. Test results indicated a significant improvement in reducing and bridging microcracks, especially in the prepeak-load region. Fracture toughness and deformability increased significantly with time. Fracture energy varied from 2.3 to 133.1 N/m, depending on age, and to some degree, on notch depth ratio. In the second stage, the FCM provided a reasonable prediction for crack initiation and propagation when only temperature effects are of concern. Age, surface conditions and structural restraint strongly

  5. Mechanical and Permeability Characteristics of Latex-Modified Pre-Packed Pavement Repair Concrete as a Function of the Rapid-Set Binder Content

    PubMed Central

    Han, Jae-Woong; Jeon, Ji-Hong; Park, Chan-Gi

    2015-01-01

    We evaluated the strength and durability characteristics of latex-polymer-modified, pre-packed pavement repair concrete (LMPPRC) with a rapid-set binder. The rapid-set binder was a mixture of rapid-set cement and silica sand, where the fluidity was controlled using a latex polymer. The resulting mix exhibited a compressive strength of ≥21 MPa and a flexural strength of ≥3.5 MPa after 4 h of curing (i.e., the traffic opening term for emergency repairs of pavement). The ratio of latex polymer to rapid-set binder material was varied through 0.40, 0.33, 0.29, and 0.25. Mechanical characterization revealed that the mechanical performance, permeability, and impact resistance increased as the ratio of latex polymer to rapid-set binder decreased. The mixture exhibited a compressive strength of ≥21 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ≤0.29. The mixture exhibited a flexural strength of ≥3.5 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ≤0.33. The permeability resistance to chloride ions satisfied 2000 C after 7 days of curing for all ratios. The ratio of latex polymer to rapid-set binder material that satisfied all conditions for emergency pavement repair was ≤0.29. PMID:28793596

  6. Mechanical and Permeability Characteristics of Latex-Modified Pre-Packed Pavement Repair Concrete as a Function of the Rapid-Set Binder Content.

    PubMed

    Han, Jae-Woong; Jeon, Ji-Hong; Park, Chan-Gi

    2015-10-01

    We evaluated the strength and durability characteristics of latex-polymer-modified, pre-packed pavement repair concrete (LMPPRC) with a rapid-set binder. The rapid-set binder was a mixture of rapid-set cement and silica sand, where the fluidity was controlled using a latex polymer. The resulting mix exhibited a compressive strength of ¥21 MPa and a flexural strength of ¥3.5 MPa after 4 h of curing (i.e., the traffic opening term for emergency repairs of pavement). The ratio of latex polymer to rapid-set binder material was varied through 0.40, 0.33, 0.29, and 0.25. Mechanical characterization revealed that the mechanical performance, permeability, and impact resistance increased as the ratio of latex polymer to rapid-set binder decreased. The mixture exhibited a compressive strength of ¥21 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.29. The mixture exhibited a flexural strength of ¥3.5 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.33. The permeability resistance to chloride ions satisfied 2000 C after 7 days of curing for all ratios. The ratio of latex polymer to rapid-set binder material that satisfied all conditions for emergency pavement repair was ¤0.29.

  7. Rheology of latex-modified grouts

    SciTech Connect

    Allan, M.L.

    1997-12-01

    The pumpability and ability of cementitious grouts to penetrate voids and cracks is strongly dependent on the rheological behavior of the grout. This is important in diverse grouting applications including ground treatment, repair of concrete, reduction of rock or soil permeability, environmental remediation, prestressing concrete, rock anchors, sealing radioactive waste repositories, and well completion. The rheology of grouts containing latex was investigated. The two latex additives used were carboxylated styrene-butadiene and acrylic. The influences of superplasticizer, fly ash, and blast furnace slag on the rheology of latex-modified grouts were addressed. Shear stress-shear rate curves were determined for a variety of mix proportions. The time-dependent behavior of selected grouts was also studied. It was determined that the yield stress and apparent viscosity are influenced by latex content and that the grouts are shear thinning at low water/cement ratios. Latex imparts stability and thixotropy in grouts. Partial replacement of cement with either fly ash or slag diminishes the effect of latex on rheology.

  8. The effects of latex additions on centrifugally cast concrete for internal pipeline protection

    SciTech Connect

    Buchheit, R.G.; Hinkebein, T.E.; Hlava, P.F.; Melton, D.G.

    1993-07-01

    Centrifugally-cast concrete liners applied to the interiors of plain steel pipe sections were tested for corrosion performance in brine solutions. An American Petroleum Institute (API) standard concrete, with and without additions of a styrene-butadiene copolymer latex, was subjected to simulated service and laboratory tests. Simulated service tests used a mechanically pumped test manifold containing sections of concrete-lined pipe. Linear polarization probes embedded at steel-concrete interfaces tracked corrosion rates of these samples as a function of exposure time. Laboratory tests used electrochemical impedance spectroscopy to study corrosion occurring at the steel-concrete interfaces. Electron probe microanalysis (EPMA) determined ingress and distribution of damaging species, such as Cl, in concrete liners periodically returned from the field. Observations of concrete-liner fabrication indicate that latex loading levels were difficult to control in the centrifugal-casting process. Overall, test results indicate that latex additions do not impart significant improvements to the performance of centrifugally cast liners and may even be detrimental. Corrosion at steel-concrete interfaces appears to be localized and the area fraction of corroding interfaces can be greater in latex-modified concretes than in API baseline material. EPMA shows higher interfacial Cl concentration in the latex-modified concretes than in the API standard due to rapid brine transport through cracks to the steel surface.

  9. Latex Admixtures for Portland Cement Concrete and Mortar

    DTIC Science & Technology

    1986-07-01

    REPAIR, EVALUATION, MAINTENANCE, AND REHABILITATION RESEARCH PROGRAM TECHNICAL REPORT REMR-CS-3 LATEX ?uJIV11XTURES t-OR PORTLAND CEMENT CONCRETE ...designating technical reports of research published under the Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Research Program identify the...problem area under which the report was prepared: cs GT HY Problem Area Concrete and Steel Structures Geotechnical Hydraulics EM El OM Problem

  10. Terminal Ballistics of Concrete-Polymer Systems

    DTIC Science & Technology

    1975-09-01

    in Portland Cement Concrete 19 8. Effects of Butyl Acrylate on Cratering 20 9. Penetiation of LMC Made with CE1-P 22 10. Cratering in Latex -Modified...Penetration Craterlng Liquid Monomers Concrete Reinforcing Patterns Terminal Ballistics Concrete Cracking Latex -Modified Concrete 20 ABSTRACT...polymerization; (3) latex modified concrete which differed from portland cement concrete only in the sub- stitution of latex emulsion for portions of the

  11. 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.

  12. 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.

  13. Latex improvement of recycled asphalt pavement

    NASA Astrophysics Data System (ADS)

    Drennon, C.

    1982-08-01

    The performance of a single unmodified milled recycled asphalt concrete was compared to milled asphalt concrete modified by addition of three types of rubber latex. Latex was added at 2, 3, 5, and 8 percent latex by weight of asphalt in the asphalt concrete. Lattices used were a styrene butadiene (SBR), a natural rubber (NR), an acrylonitrile butadiene (NBR), and four varieties of out of specification SBR lattices. Marshall tests, while indecisive, showed a modest improvement in properties of SBR and NR added material at 3 and 5 percent latex. Addition of NBR latex caused deterioration in Marshall stability and flow over that of control. Repeated load tests were run using the indirect tensile test, analyzed by the VESYS program, which computes life of pavements. Repeated load tests showed improvement in asphalt concrete life when 3 and 5 percent SBR was added. Improvement was also shown by the out of specification SBR.

  14. 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.

  15. 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.

  16. CTMP-based cellulose fibers modified with core-shell latex for reinforcing biocomposites.

    PubMed

    Pan, Yuanfeng; Xiao, Huining; Zhao, Yi; Wang, Zhuang

    2013-06-05

    The toughening of cellulose fiber reinforced polypropylene (PP) was performed via adsorbing the cationic latex with core-shell structure onto chemithermomechanical pulp (CTMP) fibers as reinforcements, which is a novel approach for rendering the surface of cellulose fibers elastomeric. The mechanical, morphological and thermal properties of the resulting biocomposites, containing 40% (wt) of the modified fibers, were investigated. The results showed that with the increasing of the latex dosage up to 2% (wt on dry CTMP fibers), the impact, tensile and flexural strengths of the modified CTMP/PP biocomposites were significantly increased. The toughening mechanism was discussed based on the retarding of crack propagation and the promoting of crystallization of PP matrix (as revealed by DSC characterization). The overall performance of the biocomposite demonstrated that cationic latex-modified CTMP fiber is very effective in reinforcing thermoplastic-based biocomposites along with the synergetic effect on enhancing crystallinity of polymer matrix.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  18. 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}.

  19. 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.

  20. Ecofriendly Fabrication of Modified Graphene Oxide Latex Nanocomposites with High Oxygen Barrier Performance.

    PubMed

    Guan, Yidan; Meyers, Kevin P; Mendon, Sharathkumar K; Hao, Guangjie; Douglas, Jessica R; Trigwell, Steve; Nazarenko, Sergei I; Patton, Derek L; Rawlins, James W

    2016-12-07

    Large-scale industrial applications of barrier films and coatings that prevent permeation of degradative gases and moisture call for the development of cost-efficient and ecofriendly polymer nanocomposites. Herein, we report the facile fabrication of latex nanocomposites (LNCs) by incorporating surface-modified graphene oxide (mGO) at various loadings (0.025-1.2 wt %) into a styrene-acrylic latex using water as the processing solvent. LNCs fabricated with mGO exhibited significant reductions (up to 67%) in water vapor sorption, resulting in greater environmental stability when compared to LNCs fabricated with equivalent loading of hydrophilic, unmodified GO. The assembly and coalescence of the exfoliated latex/mGO dispersions during the film formation process produced highly dispersed and well-ordered mGO domains with high aspect ratios, where alignment and overlap of the mGO domains improved with increasing mGO content. The addition of only 0.7 vol % (1.2 wt %) mGO led to an 84% decrease (relative to the neat polymer latex film) in oxygen permeability of the LNC films, an excellent barrier performance attributed to the observed LNC film morphologies. This work enables ecofriendly development of mechanically flexible mGO/LNC films with superior barrier properties for many industrial applications including protective coatings, food packaging, and biomedical products.

  1. Polymer-Modified Concrete for Military Construction.

    DTIC Science & Technology

    1977-04-01

    It was soon learned , however, when using epoxies and curing agents in portland cement concrete, that the cement hydration process needed...moooooooooo N400 -»in^fonNM W_1WW,JW_)PJ,J_1,-1 ooooooooooo NlflOlOWM’IOOHOV m<T>crir-»^*rvr»r»r>-vOCN Os 00 00 00 00 HNM«tm»ONCO»OH CO « o m

  2. Latex Allergy

    MedlinePlus

    ... gloves are coated with cornstarch powder, latex protein particles can stick to the cornstarch and fly into ... removed frequently, the air may contain many latex particles. SymptomsWhat are the symptoms of latex allergy?Latex ...

  3. 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- ...

  4. The increase of compressive strength of natural polymer modified concrete with Moringa oleifera

    NASA Astrophysics Data System (ADS)

    Susilorini, Rr. M. I. Retno; Santosa, Budi; Rejeki, V. G. Sri; Riangsari, M. F. Devita; Hananta, Yan's. Dianaga

    2017-03-01

    Polymer modified concrete is one of some concrete technology innovations to meet the need of strong and durable concrete. Previous research found that Moringa oleifera can be applied as natural polymer modifiers into mortars. Natural polymer modified mortar using Moringa oleifera is proven to increase their compressive strength significantly. In this resesearch, Moringa oleifera seeds have been grinded and added into concrete mix for natural polymer modified concrete, based on the optimum composition of previous research. The research investigated the increase of compressive strength of polymer modified concrete with Moringa oleifera as natural polymer modifiers. There were 3 compositions of natural polymer modified concrete with Moringa oleifera referred to previous research optimum compositions. Several cylinder of 10 cm x 20 cm specimens were produced and tested for compressive strength at age 7, 14, and, 28 days. The research meets conclusions: (1) Natural polymer modified concrete with Moringa oleifera, with and without skin, has higher compressive strength compared to natural polymer modified mortar with Moringa oleifera and also control specimens; (2) Natural polymer modified concrete with Moringa oleifera without skin is achieved by specimens contains Moringa oleifera that is 0.2% of cement weight; and (3) The compressive strength increase of natural polymer modified concrete with Moringa oleifera without skin is about 168.11-221.29% compared to control specimens

  5. Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process.

    PubMed

    Kim, Hwang-Hee; Kim, Chun-Soo; Jeon, Ji-Hong; Park, Chan-Gi

    2016-01-29

    To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene (SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate

  6. Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process

    PubMed Central

    Kim, Hwang-Hee; Kim, Chun-Soo; Jeon, Ji-Hong; Park, Chan-Gi

    2016-01-01

    To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene (SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate

  7. Thermal behavior of crumb-rubber modified asphalt concrete mixtures

    NASA Astrophysics Data System (ADS)

    Epps, Amy Louise

    Thermal cracking is one of the primary forms of distress in asphalt concrete pavements, resulting from either a single drop in temperature to an extreme low or from multiple temperature cycles above the fracture temperature of the asphalt-aggregate mixture. The first mode described is low temperature cracking; the second is thermal fatigue. The addition of crumb-rubber, manufactured from scrap tires, to the binder in asphalt concrete pavements has been suggested to minimize both types of thermal cracking. Four experiments were designed and completed to evaluate the thermal behavior of crumb-rubber modified (CRM) asphalt-aggregate mixtures. Modified and unmodified mixture response to thermal stresses was measured in four laboratory tests. The Thermal Stress Restrained Specimen Test (TSRST) and the Indirect Tensile Test (IDT) were used to compare mixture resistance to low temperature cracking. Modified mixtures showed improved performance, and cooling rate did not affect mixture resistance according to the statistical analysis. Therefore results from tests with faster rates can predict performance under slower field rates. In comparison, predicted fracture temperatures and stresses (IDT) were generally higher than measured values (TSRST). In addition, predicted fracture temperatures from binder test results demonstrated that binder testing alone is not sufficient to evaluate CRM mixtures. Thermal fatigue was explored in the third experiment using conventional load-induced fatigue tests with conditions selected to simulate daily temperature fluctuations. Test results indicated that thermal fatigue may contribute to transverse cracking in asphalt pavements. Both unmodified and modified mixtures had a finite capacity to withstand daily temperature fluctuations coupled with cold temperatures. Modified mixtures again exhibited improved performance. The fourth experiment examined fracture properties of modified and unmodified mixtures using a common fracture toughness test

  8. Construction Productivity Advancement Research (CPAR) Program. Investigation of Modified Sulfur Concrete as a Structural Material

    DTIC Science & Technology

    1993-07-01

    Industrial applications of modified sulfur concrete (MSC) have been extremely successful in areas of high corrosive activity such as load-bearing...The ductility of MSC in the postyield regime, however, has not been determined in these tests. Bond strength, Modified sulfur concrete , Strength

  9. Influence of Aggregate Coated with Modified Sulfur on the Properties of Cement Concrete

    PubMed Central

    Lee, Swoo-Heon; Hong, Ki-Nam; Park, Jae-Kyu; Ko, Jung

    2014-01-01

    This paper proposes the mixing design of concrete having modified sulfur-coated aggregate (MSCA) to enhance the durability of Portland cement concrete. The mechanical properties and durability of the proposed MSCA concrete were evaluated experimentally. Melting-modified sulfur was mixed with aggregate in order to coat the aggregate surface at a speed of 20 rpm for 120 s. The MSCA with modified sulfur corresponding to 5% of the cement weight did not significantly affect the flexural strength in a prism concrete beam specimen, regardless of the water-cement ratio (W/C). However, a dosage of more than 7.5% decreased the flexural strength. On the other hand, the MSCA considerably improved the resistance to the sulfuric acid and the freezing-thawing, regardless of the sulfur dosage in the MSCA. The coating modified sulfur of 5% dosage consequently led to good results for the mechanical properties and durability of MSCA concrete. PMID:28788703

  10. An Exploratory Compressive Strength Of Concrete Containing Modified Artificial Polyethylene Aggregate (MAPEA)

    NASA Astrophysics Data System (ADS)

    Hadipramana, J.; Mokhatar, S. N.; Samad, A. A. A.; Hakim, N. F. A.

    2016-11-01

    Concrete is widely used in the world as building and construction material. However, the constituent materials used in concrete are high cost when associated with the global economic recession. This exploratory aspires to have an alternative source of replacing natural aggregate with plastic wastes. An investigation of the Modified Artificial Polyethylene Aggregate (MAPEA) as natural aggregate replacement in concrete through an experimental work was conducted in this study. The MAPEA was created to improve the bonding ability of Artificial Polyethylene Aggregate (APEA) with the cement paste. The concrete was mixed with 3%, 6%, 9%, and 12% of APEA and MAPEA for 14 and 28 curing days, respectively. Furthermore, the compressive strength test was conducted to find out the optimum composition of MAPEA in concrete and compared to the APEA concrete. Besides, this study observed the influence and behaviour of MAPEA in concrete. Therefore, the Scanning Electron Microscopy was applied to observe the microstructure of MAPEA and APEA concrete. The results showed the use of high composition of an artificial aggregate resulted inferior strength on the concrete and 3% MAPEA in the concrete mix was highest compressive strength than other content. The modification of APEA (MAPEA) concrete increased its strength due to its surface roughness. However, the interfacial zone cracking was still found and decreased the strength of MAPEA concrete especially when it was age 28 days.

  11. 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.

  12. Latex Allergy

    MedlinePlus

    ... Allergic contact dermatitis. This reaction to the chemical additives used during manufacturing produces signs and symptoms — usually ... they're common in your family. Connection between food allergy and latex allergy Latex allergy also is ...

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

    PubMed

    Karadelis, John N; Lin, Yougui

    2015-09-01

    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].

  15. Ion chromatography on carbon clad zirconia modified by diazonium chemistry and functionalized latex particles.

    PubMed

    Wahab, M Farooq; Pohl, Christopher A; Lucy, Charles A

    2011-08-07

    This work explores the potential of 3 μm carbon coated zirconia particles as a stationary phase for ion chromatography for the separation of organic acids and inorganic ions. A 4-phenylsulfonic acid functionality is introduced onto the carbon surface by reducing 4-phenylsulfonic acid diazonium chloride with borohydride in the presence of carbon clad zirconia particles. The elemental sulfur analysis gave 132 μeq-SO(3)H/g carbon clad zirconia and 2% S atomic concentration by XPS analysis. The -SO(3)(-) groups serve as electrostatic anchors for latex nanoparticles bearing quaternary triethylamine functional groups. The agglomeration step in 5 × 0.4 cm i.d. columns converts the packed particles into an anion exchanger. The breakthrough curves with nitrate indicate a capacity of 3 μeq/column. Separation of common organic acids and inorganic ions using carbonate eluent and suppressed conductivity detection yield plate heights (H) of 0.023-0.05 mm.

  16. A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO2/Ag-exchanged-zeolite-A nanocomposite

    NASA Astrophysics Data System (ADS)

    Nosrati, Rahimeh; Olad, Ali; Nofouzi, Katayoon

    2015-08-01

    The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO2/Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV-visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO2/Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO2/Ag-exchanged-zeolite-A nanocomposite additive with TiO2 to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination.

  17. 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.

  18. Preparation and application of nanocrystalline cellulose derived from sugarcane waste as filler modified alkanolamide on crosslink of natural rubber latex film

    NASA Astrophysics Data System (ADS)

    Harahap, Hamidah; Hayat, Nuim; Lubis, Marfuah

    2017-07-01

    Sugarcane waste is abundant sources of cellulose and it has potential to reutilize. Cellulose from sugarcane waste can be derived into nanocystalline cellulose (NCC) from crystalline region. The NCC as a filler has capability to reinforce natural rubber latex product. The crosslink in vulcanized natural rubber latex film influences several properties of product. In this work, we extracted NCC from sugarcane waste then added into natural rubber latex as filler modified alkanolamide (ALK) and also studied the crosslink of natural rubber latex films. NCC were produced from sugarcane waste by hydrolysis process with sulfuric acid 45%. The obtained NCC was characterized by using x-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infra red (FTIR). NCC was modified by alkanolamide and dispersed in water with filler concentration of 10%. Then the dispersion were added into latex system followed by pre-vulcanization at 70 °C. The films were prepared by coagulant dipping method and dried at 100 °C and 120 °C for 20 minutes. Characterization of NCC from sugarcane waste by using FTIR was done, it clearly showed the functional groups of cellulose. TEM showed the obtained NCC were rod-shaped with about 40-160 nm in diameter and several hundred nm in length, and XRD showed that the degree of crystalinity of NCC from sugarcane waste is 92.33%. The crosslink of natural rubber films were studied by measure the crosslink density for different filler loading by using swelling measurement with toluene solution. The result show that the crosslink density increased in line with amount of filler which added into the system, and also the crosslink density that obtained from vulcanization at 120 °C were higher than 100 °C.

  19. Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning

    PubMed Central

    Marks, Michał; Glinicki, Michał A.; Gibas, Karolina

    2015-01-01

    The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions’ penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration. PMID:28793740

  20. Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning.

    PubMed

    Marks, Michał; Glinicki, Michał A; Gibas, Karolina

    2015-12-11

    The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions' penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration.

  1. Reinforcement effect of soy protein nanoparticles in amine-modified natural rubber latex

    USDA-ARS?s Scientific Manuscript database

    Mechanical properties of natural rubber reinforced with soy protein nanoparticles are useful for various rubber applications. However, the properties is further improved by improving interactions between soy protein and rubber. A novel method is used to modify particle surface of natural rubber late...

  2. Modified Electrical Resistivity Survey for Leakage Assessment of a Waterside Concrete Barrage

    NASA Astrophysics Data System (ADS)

    Lee, B.; Oh, S.; Hong, J.

    2015-12-01

    An modified electrical resistivity survey has been suggested and applied to a leakage detection problem of concrete barrage. We suggest the modified electrical resistivity methods using electrodes floating on the water and apply line current sources instead of conventional point current sources in order to facilitate simple analysis. Furthermore, the study applied the following three variations of modified electrode array: Direct potential array, Parallel potential array and Cross potential array. In this study, first, the characteristics of potential difference graph by array during water leakage were confirmed from the numerical analysis. Next, a experiments on the effect factor of the filed geophysical exploration were conducted by using a barrage model. And then, modified electrode arrays were applied to the concrete barrage in practice in Korea. Finally, all of the results have been compared and analyzed in order to determine the applicability of three modified electrode arrays to water leakage detection of a concrete barrage. As a result, when water leakage occurred, all kind of array operations demonstrated a distinct change of aspect of potential difference in the numerical analysis, model experiment and field geophysical exploration graphs. Therefore, this modified electrode array of electrical resistivity survey, which has been adapted to the concrete barrage, has been found to be a useful method to detect water leakage.

  3. Thermoplastic starch modified with microfibrillated cellulose and natural rubber latex: A broadband dielectric spectroscopy study.

    PubMed

    Drakopoulos, S X; Karger-Kocsis, J; Kmetty, Á; Lendvai, L; Psarras, G C

    2017-02-10

    Thermoplastic starch (TPS) biocomposites modified with cellulose microfibers and/or natural rubber were prepared via extrusion compounding. Glycerol and water served as plasticizers for starch. The dielectric properties of the TPS composites were examined via broadband dielectric spectroscopy in the temperature and frequency ranges of 30°C-65°C and 0.1Hz-10MHz, respectively. Each specimen was tested twice in order to study the effect of absorbed water. The hydrophobic/hydrophilic character of the modifiers governed the dielectric performance of the corresponding TPS biocomposites. Conducted analysis revealed two relaxation processes attributed to matrix-water-reinforcement interfacial polarization and glass to rubber transition of the TPS. Evaporation of water significantly affected the first process and only slightly the second one. Energy density, prior and after water evaporation, was also determined at constant field. By employing dielectric reinforcing function the contributions of water-assisted and constituents' originated interfacial phenomena could be separated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. 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

  5. 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.

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

    SciTech Connect

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

    1999-05-01

    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 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, the authors 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.

  7. Modified virtual internal bond model for concrete subjected to dynamic loading

    NASA Astrophysics Data System (ADS)

    Patil, Mayuri

    Concrete is often used as a primary material to build protective structures. There is a wide range of research work being performed to simulate the behavior of reinforced concrete under impact and blast loading. This behavior is studied from both material and structural points of view. The research study presented in this thesis focuses on material aspects of modeling. LS-DYNARTM is an effective software for modeling and finite element analysis of structural members. It allows the user to define the material through commercially available or user-defined constitutive material models. Each material model has a distinct set of parameters to define a material which is further assigned to elements and used for simulations. This research study presents a user defined material model called Modified Concrete Virtual Internal Bond Model (MC-VIB). The basic constitutive model of VIB assumes the body as a collection of randomly oriented material points interconnected by a network of internal bonds. The model was modified by several researchers for different purposes. This research presents the MC-VIB for concrete under dynamic loading and studies its implementation into LS-DYNARTM. The modifications include incorporation of shear behavior and accounting for the difference in behavior of concrete in tension and compression. This project includes the calibration of the model based on stress-strain behavior of single element and cylinder model of concrete. The parameters are based on concrete with a uniaxial compressive strength of 27.6 MPa (4 ksi). These numerical curves are compared to those obtained from conventionally used material models for concrete and standard curves obtained by accepted equations to check the accuracy of prediction. The material model available in LS-DYNARTM requires a number of input parameters to define concrete behavior. These properties are normally derived from actual tests performed on the concrete under consideration. Often the properties are

  8. Latex allergy.

    PubMed

    Gawchik, Sandra M

    2011-01-01

    Allergy to natural rubber latex is an important clinical condition that occurred after the institution of universal precautions to protect healthcare workers. A rapid increase and production of both examination and surgical gloves resulted in an epidemic of allergy to latex protein. Healthcare workers in both the medical and dental environments, as well as specific groups of individuals including those with spina bifida, myelodysplasia, and food allergies (banana, kiwi, avocado, and others), were at increased risk of sensitization. Clinical symptoms in the latex allergic individual ranged from type I hypersensitivity reaction including rhinoconjunctivitis, asthma, and systemic reaction to type IV hypersensitivity reaction, which occur from the chemicals added during the manufacturing process. Diagnosis of latex allergy is based on a clinical history that correlates the development of symptoms in relationship to exposure. In the United States there are no skin tests approved by the Food and Drug Administration. Therefore a combination of clinical judgment and serologic testing such as ImmunoCAP and Immulite is helpful. The primary treatment of latex allergy is avoidance of exposure to the latex protein.

  9. Application of Nano Fe(III)-Tannic Acid Complexes in Modifying Aqueous Acrylic Latex for Controlled-Release Coated Urea.

    PubMed

    Shen, Yazhen; Du, Changwen; Zhou, Jianmin; Ma, Fei

    2017-02-08

    Acrylic latexes are valuable waterborne materials used in controlled-release fertilizers. Controlled-release urea coated with these latexes releases a large amount of nutrients, making it difficult to meet the requirement of plants. Herein, Fe(III)-tannic acid (TA) complexes were blended with acrylic latex and subsequently reassembled on a surface of polyacrylate particles. These complexes remarkably retarded the release of urea (the preliminary solubility was decreased from 22.3 to 0.8%) via decreasing the coating tackiness (Tg was increased from 4.17 to 6.42 °C), increasing the coating strength (tensile stress was improved from 3.88 to 4.45 MPa), and promoting the formation of denser structures (surface tension was decreased from 37.37 to 35.94 mN/m). Overall, our findings showed that a simple blending of Fe(III)-TA complexes with acrylic latex produces excellent coatings that delay the release of urea, which demonstrates great potential for use in controlled-release fertilizers coated with waterborne polymers.

  10. High temperature performance of scrap tire rubber modified asphalt concrete

    SciTech Connect

    Coomarasamy, A.; Manolis, S.; Hesp, S.

    1996-12-31

    Wheel track rutting tests on mixes modified with 30 mesh, 80 mesh, and very fine colloidal crumb rubber particles show that a very significant improvement in performance occurs with a reduction in the rubber particle size. The SHRP binder test for rutting, which was originally developed for homogeneous systems only, does not predict the performance improvement for smaller rubber particles. If these new scrap rubber binder systems are to be used in pavements then rutting tests on the asphalt-aggregate mixture should be conducted in order to accurately predict high temperature performance.

  11. An assessment of SBS modified asphalt concrete pavements performance features performing numerical analysis

    NASA Astrophysics Data System (ADS)

    Karakas, Ahmet Sertac; Bozkurt, Tarik Serhat; Sayin, Baris; Ortes, Faruk

    2017-07-01

    In passenger and freight traffic on the roads, which has the largest share of the hot mix asphalt (HMA) prepared asphalt concrete pavement is one of the most preferred type of flexible superstructure. During the service life of the road, they must provide the performance which is expected to show. HMA must be high performance mix design, comfortable, safe and resistance to degradation. In addition, it becomes a critical need to use various additives materials for roads to be able to serve long-term against environmental conditions such as traffic and climate due to the fact that the way of raw materials is limited. Styrene Butadiene Styrene (SBS) polymers are widely used among additives. In this study, the numerical analysis of SBS modified HMA designed asphalt concrete coatings prepared with different thicknesses with SBS modified HMA is performed. After that, stress and deformation values of the three pavement models are compared and evaluated.

  12. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. [Latex allergy].

    PubMed

    Pacor, M L; Biasi, D; Cortina, P; Maleknia, T; Lunardi, C

    1995-03-01

    In 1979 the first case of contact urticaria to rubber gloves was reported in a patient with a positive skin prick test to latex. The use of articles containing rubber is widespread and this can explain the increasing frequency of allergic reactions to natural rubber latex. The symptoms may be localized like contact urticaria or systemic like angioedema, generalized urticaria or anaphylactic shock. In this study we have considered 12 patients who presented clinical manifestations after direct contact with objects containing rubber. Three patients had eczema and pruritus after the use of household gloves, 4 subjects had lips and tongue oedema following the contact with rubber tube during a dental treatment, 5 patients suffered from urticaria and pruritus during the use of surgical gloves. Generalized angioedema was also present in 4 out of 12 patients. All the patients had positive Skin prick test and Rast to latex. Three out of 12 patients were atopic. Our study confirms the increasing frequency of immediate hypersensitivity reactions to latex. This phenomenon must be taken into account especially before surgery, since severe clinical manifestations such as anaphylactic shock may occur.

  14. 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.

  15. 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

  16. 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.

  17. Degree of dispersion of latex particles in cement paste, as assessed by electrical resistivity measurement

    SciTech Connect

    Fu, X.; Chung, D.D.L.

    1996-12-31

    The degree of dispersion of latex particles in latex-modified cement paste was assessed by measurement of the volume electrical resistivity and modeling this resistivity in terms of latex and cement phases that are partly in series and partly in parallel. The assessment was best at low values of the latex-cement ratio; it underestimated the degree of latex dispersion when the latex/cement ratio was high, especially > 0.2.

  18. 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.

  19. Use of hydrophobically modified inulin for the preparation of polymethyl methacrylate/polybutyl acrylate latex particles using a semicontinuous reactor.

    PubMed

    Obiols-Rabasa, M; Ramos, J; Forcada, J; Esquena, J; Solans, C; Levecke, B; Booten, K; Tadros, Tharwat F

    2010-06-01

    The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTEC SP1, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SP1, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanoparticles, at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity, at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SP1 and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SP1 by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.

  20. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches

    PubMed Central

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-01-01

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%–1.5%, in terms of shear performance. PMID:28788364

  1. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches.

    PubMed

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-10-23

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%-1.5%, in terms of shear performance.

  2. Improvement of the performances of modified bituminous concrete with EVA and EVA-waste

    NASA Astrophysics Data System (ADS)

    Saoula, S.; Ait Mokhtar, K.; Haddadi, S.; Ghorbel, E.

    2009-11-01

    The improvement of the characteristics of the road flexible pavements is essential in regard to the growth of the traffics and the increasingly large performances of the vehicles. This improvement was made possible by the introduction of new methods and processes of modification of the products. The modification of the bituminous mix can be made in two manners: the first one is the modification of the bitumen binder (process A), the other one consists of the direct addition of a modifier during mixing operation (process B). It should be noted that one of the difficulties in Algeria is the absence of manufacturing units of the modified binders. For this reason, it is recommended to use the process B. In this article, the results of the influence of the modification of a bituminous concrete on its mechanical behaviour have been presented, using laboratory tests by the addition of EVA (Acetate of vinyl and ethylene) and of EVA-waste (waste of sole of shoes).

  3. Corrosion inhibition of reinforcing steel by using acrylic latex

    SciTech Connect

    Wang, S.X.; Lin, W.W.; Ceng, S.A.; Zhang, J.Q.

    1998-05-01

    Acrylic latex was introduced into steel-reinforcing steel concrete as concrete admixtures or rebar coatings in order to prevent corrosion of steel reinforcements. The results showed that applying the latex by both methods took effect in different ways, while the latter was more noticeable. The corrosion prevention mechanism and the surface state of the steel rebar were also explored, based on which suggestions for enhancing the corrosion-resistant ability were made.

  4. Comparison of Transport of Carboxylate-Modified Latex Microspheres and Silica Colloids in Fractured and Porous Media: The Case for Microspheres as Conservative Colloid Tracers

    NASA Astrophysics Data System (ADS)

    Anghel, I.; Haga, M. J.; Reimus, P. W.

    2001-12-01

    Carboxylate-modified latex (CML) polystyrene microspheres have frequently been used as colloid tracers in laboratory and field tracer experiments because of the ability to discriminate them from natural colloids and to achieve very low detection limits by tagging them with fluorescent dyes. However, the use of CML microspheres as surrogates for inorganic colloids to obtain estimates of colloid transport parameters for use in predictive models is sometimes called into question because there are many differences in the physical and chemical characteristics of the two types of colloids. We conducted several transport experiments in both fractured and porous media to compare the transport behavior of CML microspheres and silica colloids. Silica colloids were used to represent inorganic colloids because previous experiments had established that they transported through fractures with less attenuation than montmorillonite colloids. We conducted fracture experiments at varying flow rates and in both vertical and horizontal fracture orientations. We found that the microspheres always had either the same attenuation or less attenuation than the silica colloids, with the greatest difference occurring at low flow rates and in the horizontal fracture orientation. The greater silica attenuation in the horizontal orientation was largely due to gravitational settling, which did not noticeably affect the CML microspheres, despite their greater size compared to the silica (330 vs. 100 nm), because of the near-neutral buoyancy of the polystyrene latex (density = 1.06 g/ml). The smaller silica colloids also presumably had more collisions with fracture walls in either orientation because of their larger diffusivity compared to the CML microspheres. This greater number of collisions apparently resulted in greater attenuation, even in the vertical orientation. The results of the porous media experiments were generally consistent with the fracture experiment results. Our preliminary

  5. The methods of receiving coal water suspension and its use as the modifying additive in concrete

    NASA Astrophysics Data System (ADS)

    Buyantuyev, S. L.; Urkhanova, L. A.; Lkhasaranov, S. A.; Stebenkova, Y. Y.; Khmelev, A. B.; Kondratenko, A. S.

    2017-01-01

    Results of research of the coal water suspension (CWS) from a cake received in the electrodigit ways in the fluid environment and gas are given in article and also the possibilities of its use as the modifying additive in concrete are considered. Use of a coal cake is perspective as it is a withdrawal of the coal and concentrating enterprises and has extremely low cost. Methods of receiving CWS and possibility of formation of carbon nanomaterials (CNM) are given in their structure. Research and the analysis of a microstructure of a surface of exemplars before electrodigit processing, their element structure, dependence of durability of a cement stone on a look and quantity of an additive of CWS is conducted. For modification of cement the carbon nanomaterials received from the following exemplars of water coal suspensions were used: foams from a cake from a scrubber of the plasma modular reactor, coal water suspension from a cake from electrodigit installation. The product which can find further application for a power engineering as fuel for combustion, and also in structural materials science, in particular, as the modifying additive in concrete allows to receive these methods.

  6. 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

  7. 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.

  8. Properties of concrete modified with waste Low Density Polyethylene and saw dust ash

    NASA Astrophysics Data System (ADS)

    Srimanikandan, P.; Sreenath, S.

    2017-07-01

    The increase in industrialization creates need for disposal of large quantity of by-products. To overcome the difficulty of disposal, these by-products can be used as a replacement for raw material. In this concern, non-conventional industrial wastes such as plastic bags, PET bottles, pulverized waste Low Density Polyethylene (LDPE) and biological waste such as saw-dust ash, coconut coir were used as a replacement in concrete. In this project, saw-dust ash and pulverized waste LDPE were introduced as the partial replacement for cement and fine aggregates respectively. 0%, 5%, 10%, 15% and 20% of sand by volume was replaced with LDPE and 0%, 1%, 3%, 5% and 10% of cement by volume was replaced with saw dust ash. Standard cube, cylinder and prism specimens were cast to assess the compressive strength, split tensile strength and flexural strength of modified concrete after 28 days of curing. Optimum percentage of replacement was found by comparing the test results. The mix with 5% of LDPE and 3% of saw dust ash showed a better result among the other mixes.

  9. Performance testing of asphalt concrete containing crumb rubber modifier and warm mix additives

    NASA Astrophysics Data System (ADS)

    Ikpugha, Omo John

    Utilisation of scrap tire has been achieved through the production of crumb rubber modified binders and rubberised asphalt concrete. Terminal and field blended asphalt rubbers have been developed through the wet process to incorporate crumb rubber into the asphalt binder. Warm mix asphalt technologies have been developed to curb the problem associated with the processing and production of such crumb rubber modified binders. Also the lowered production and compaction temperatures associated with warm mix additives suggests the possibility of moisture retention in the mix, which can lead to moisture damage. Conventional moisture sensitivity tests have not effectively discriminated good and poor mixes, due to the difficulty of simulating field moisture damage mechanisms. This study was carried out to investigate performance properties of crumb rubber modified asphalt concrete, using commercial warm mix asphalt technology. Commonly utilised asphalt mixtures in North America such as dense graded and stone mastic asphalt were used in this study. Uniaxial Cyclic Compression Testing (UCCT) was used to measure permanent deformation at high temperatures. Indirect Tensile Testing (IDT) was used to investigate low temperature performance. Moisture Induced Sensitivity Testing (MiST) was proposed to be an effective method for detecting the susceptibility of asphalt mixtures to moisture damage, as it incorporates major field stripping mechanisms. Sonnewarm(TM), Sasobit(TM) and Evotherm(TM) additives improved the resistance to permanent deformation of dense graded mixes at a loading rate of 0.5 percent by weight of the binder. Polymer modified mixtures showed superior resistance to permanent deformation compared to asphalt rubber in all mix types. Rediset(TM) WMX improves low temperature properties of dense graded mixes at 0.5 percent loading on the asphalt cement. Rediset LQ and Rediset WMX showed good anti stripping properties at 0.5 percent loading on the asphalt cement. The

  10. [Latex allergy in children].

    PubMed

    Mavale-Manuel, S; Paty, E; Scheinmann, P; de Blic, J

    2003-08-01

    The aim of our study was to determine the prevalence of latex allergy and the clinical features of children with latex allergy. We prospectively investigated 243 children consulting in our allergy out-patients unit during 1 year. Parents answered a questionnaire, and children underwent skin prick tests with common allergens and latex. Latex-specific serum immunoglobulin E was determined by CAP test in children with latex sensitization. The results were compared in children with and without latex allergy. The prevalence of latex allergy was 1.3%. A family history of atopy (75%) and a personal history of previous surgery was associated with latex allergy (P < 0.0001). In children with latex allergy, the frequency of sensitization to inhaled and food allergens, atopic dermatitis, rhinitis and conjunctivitis was higher than in children without latex allergy (P < 0.05). Avocado allergy was the food allergy most commonly associated with clinical symptoms. Balloon was the most common latex product causing symptoms (60%). Due to its potential severe consequences, latex allergy should be investigated in children who had undergone multiple surgical procedures and in the children with pollen-food allergy syndrome. Avoidance of latex is an important preventive measure.

  11. Improving the bond strength between steel rebar and concrete by ozone treatment of rebar and polymer addition to concrete

    SciTech Connect

    Fu, X.; Chung, D.D.L.

    1997-05-01

    Ozone treatment of steel rebar, together with latex addition (20% by weight of cement) to concrete, resulted in a 39% increase in the shear bond strength between rebar and concrete, compared to a 25% increase resulted from either ozone treatment alone or latex addition alone. Ozone treatment and latex addition resulted in similarly small increases in the contact electrical resistivity between rebar and concrete. Methylcellulose addition (0.4% by weight of cement) to concrete gave slightly less bond strength increase than the latex addition, but did not affect the contact resistivity.

  12. Neonatal sensitization to latex.

    PubMed

    Worth, J

    2000-05-01

    Babies born in delivery rooms of hospitals are exposed to latex through skin and mucous membrane contact with prepowdered latex gloves worn by midwives and doctors, and through the inhalation of latex-bound starch powder in the air of the delivery room. This paper examines the hypothesis that they are at risk for latex sensitization, and that part of the sharp increase of childhood asthma, eczema and anaphylaxis in the past 30-40 years may be linked. These possibilities seem hitherto unsuspected. In over 700 papers on latex allergy no mention of neonatal exposure to latex has been found. Even obstetric papers discussing the risks for an atopic mother (atopy - a tendency to develop allergies) do not seem to anticipate any risk for the baby, who might also be atopic. Latex allergy is primarily regarded as an occupational hazard. This paper suggests that it is a hazard for every baby handled by latex gloves at birth. Copyright 2000 Harcourt Publishers Ltd.

  13. Latex agglutination test

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003334.htm Latex agglutination test To use the sharing features on this page, please enable JavaScript. The latex agglutination test is a laboratory method to check ...

  14. 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…

  15. Detection of enterotoxigenicity of Staphylococcus aureus strains: a comparative use of the modified Ouchterlony precipitation test, reversed passive latex agglutination test, and avidin-biotin ELISA.

    PubMed

    Adesiyun, A A; Eschbach, M; Lenz, W; Schaal, K P

    1992-11-01

    The avidin-biotin enzyme-linked immunosorbent assay (ELISA), reversed passive latex agglutination (RPLA) test, and the modified Ouchterlony precipitation test (MOPT) were compared in detecting enterotoxin production by Staphylococcus aureus strains. A total of 1015 strains isolated from human beings, animals, and foods were tested for staphylococcal enterotoxins A (SEA), B (SEB), and C (SEC). Of these, 495 (48.8%), 467 (46.0%), and 204 (20.1%) were classified as enterotoxigenic by the ELISA, RPLA test, and MOPT, respectively. The difference in the number of strains classified as enterotoxigenic by the ELISA and RPLA test was not significant (P > or = 0.05; chi 2), but both tests detected significantly (P < 0.001; chi 2) more enterotoxigenic strains than the MOPT. The combined use of the three assay systems classified 258 (25.4%), 278 (27.4%), and 263 (25.9%) of 1015 strains tested as positive for SEA, SEB, and SEC, respectively. However, the three systems were all positive in only 29.1% of SEA-producing strains, 32.0% of SEB-producing strains, and 25.1% of SEC-producing strains. The MOPT was negative when the corresponding ELISA and RPLA test were positive (46.9% for SEA, 43.5% for SEB, and 40% for SEC); the RPLA test was negative when the corresponding ELISA was positive (10.5% for SEA, 15.5% for SEB, and 25.5% for SEC); and the ELISA was negative when the RPLA test was positive (13.6% for SEA, 9.0% for SEB, and 9.5% for SEC). All factors considered, the RPLA test appears most suitable for quantitatively screening large numbers of strains for staphylococcal enterotoxins.

  16. Repair, Evaluation, Maintenance, and Rehabilitation Research Program Overlays on Horizontal Concrete Surfaces: Case Histories

    DTIC Science & Technology

    1994-02-01

    thermal expansion and contraction and autogenous shrinkage. No attempt was made to repair the cracks. During an inspection in August of 1984, it was...LATEX- ’ * """* 9 MODIFIED CONCRETE SLOPE PATCH IF NECESSARY EXOSTING CRACK TO MAINTAIN DRAINAGE Figure 27. Typical surface repair, Mississippi River...102-mm) deep densely graded aggregate base. The sand base extended to the ditch foreslopes to provide drainage of subbase. The average daily

  17. Managing latex allergies at home

    MedlinePlus

    ... proteins that are in latex. These foods include: Bananas Avocado Chestnuts Other foods that are less strongly ... Asthma and Immunology. Latex Cross-reactive Foods Fact Sheet. Updated October 8, 2015. latexallergyresources.org/latex-cross- ...

  18. 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.

  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. Latex allergy: past and present.

    PubMed

    Meade, B Jean; Weissman, David N; Beezhold, Donald H

    2002-02-01

    Although latex products have been in use for over a century, allergic responses to latex proteins have only been recognized as a serious health problem for the past 15 years. Latex allergy particularly affects two groups, health care workers (HCW) and children with spina bifida (SB). This manuscript provides a brief history of latex allergy, and a review of the following: the manufacturing process for dipped latex products, the 11 latex allergens that have been characterized and received allergen designations by the International Union of Immunological Societies, the methods used in exposure assessment, the epidemiology and clinical management of latex allergy, and the use of animal models in investigating mechanisms underlying latex allergy.

  1. Latex allergy in children.

    PubMed

    Niggemann, B; Breiteneder, H

    2000-02-01

    Natural rubber is a component of the latex of the tropical Hevea brasiliensis tree which is widely used in the manufacturing of medical devices and a large variety of articles for everyday use. Over a dozen allergens have been identified in the latex of H. brasiliensis. The allergens Hev b 1, Hev b 3, Hev b 6, and Hev b 7 are proteins that are involved in the biosynthesis of rubber or the coagulation of latex. Allergens that are part of the plant's defense system are represented by Hev b 2 and class I endochitinases. The allergens Hev b 4, Hev b 5, and Hev b 8-10 were classified as either structural or housekeeping proteins. Immediate-type hypersensitivity reactions to proteins present in Hevea latex were first described in 1927. Since then, natural rubber latex (NRL) allergy has become an important medical problem for an increasing number of individuals. Sensitization mainly occurs by wound or mucosal contact with NRL devices during surgery or by inhalation of airborne allergens released from powdered latex gloves. The number of surgical interventions and an atopic disposition are the most important risk factors for developing latex allergy, especially in children with spina bifida. Exposure to NRL products should be carefully avoided for individuals who belong to high-risk groups. Initial studies on establishing a latex-free environment for surgery in all spina bifida patients have reported on a decrease in sensitization and allergy to NRL.

  2. Prevention of latex allergy among health care workers: evaluation of the extractable latex protein content in different types of medical gloves.

    PubMed

    Crippa, Michela; Belleri, Luca; Mistrello, Gianni; Carsana, Teresina; Neri, Gloria; Alessio, Lorenzo

    2003-07-01

    Since the 1980s, there has been increased use of latex gloves by health care workers and a concomitant increase of irritant and allergic reactions. The total protein content and the latex allergenic protein content in different types of medical gloves commonly used in our hospital were evaluated to acquire information useful for preventing latex allergy in our hospital personnel. The total protein content and the allergic latex protein contents were evaluated with Lowry modified method and RAST inhibition assay in samples and extracts of 29 different types of medical gloves. The highest concentrations of total proteins and allergenic latex proteins were found in examination powdered latex gloves and in surgical powdered latex gloves; a significant amount of latex proteins was found in some brands of nitrile gloves. The clear association between the total protein levels and the allergenic latex protein levels suggests that the gloves with highest total protein content have the greatest allergenic potential. Therefore, it is recommended that manufacturing companies should provide package inserts including the total protein contents and possibly allergenic latex protein levels. They should declare whether they have added latex to their nitrile glove formulation. RAST-inhibition assays directly on glove samples instead of glove extract seems to be a good reliable and faster alternative for the evaluation of the allergenic potential of latex gloves. Copyright 2003 Wiley-Liss, Inc.

  3. 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.

  4. [Latex: a complex allergy].

    PubMed

    Ferreira, M B; Carlos, A G

    1999-01-01

    The authors review several of the most important aspects of latex allergy, an increasing problem in Public Health, which should be understood by all health professionals. After briefly presenting the history of the origin latex, from Hevea brasiliensis the authors describe the antigens of latex: Hev b1 to Hev b8, major allergens. They also note the crossed reactivity not only with foods, exotic fruits, but also with pneumoallergens and in particular the pollens. The groups at risk are essentially workers in the latex industry, health professionals and finally infants with spina bifida or other severe urological anomaly. The clinical signs are reactions of type 1 hypersensitivity, to urticaria and/or angio-oedema and anaphylactic shock. Diagnosis is based on a search for specific serum IgE, skin tests and provocation tests. Prophylaxis depends on removal of all substances that are based on latex, especially replacement of gloves with vinyl, but also on a food diet that excludes all foods that have a cross-reactivity with latex.

  5. Polymer Latex Stability Modification by Exposure to Hydrophobic Solvents.

    PubMed

    de Oliveira Cardoso A; Galembeck

    1998-08-01

    The stability of latex particles toward coagulation in the presence of salt is modified by swelling the latex with toluene and chloroform vapors. Short-term stability was determined by turbidimetric titrations, and the long-term stability was evaluated by adding latex and salt solutions, allowing the mixture to age for 24 or 48 h and determining the characteristics of the supernatant and of the sediment. Nine different latexes were examined, with variable results: in some cases, both apolar solvents stabilize the latex; in other cases, increased stability is induced by only one of the solvents, either toluene or chloroform. There is also coherence, but not a strict correlation, between the solvent effects on short- and long-term stability. For instance, in the case of a core-and-shell styrene-butyl methacrylate latex, chloroform has a small stabilizing effect in the titration experiment, but it prevents the formation of a coagulated latex sediment even 48 h after mixing latex and salt. Two hypotheses are discussed to account for these observations: (i) swelling solvents decrease the particles ability to dissipate the collision kinetic energy, so that particles collide but without joining each other; (ii) the solvents induce the release of trapped charged groups from the particle interior to the interface, enhancing the usual (electrostatic, steric, hydration) stability factors. Copyright 1998 Academic Press.

  6. Latex allergens in tire dust and airborne particles.

    PubMed Central

    Miguel, A G; Cass, G R; Weiss, J; Glovsky, M M

    1996-01-01

    The prevalence and severity of latex allergy has increased dramatically in the last 15 years due to exposure to natural rubber products. Although historically this health risk has been elevated in hospital personnel and patients, a recent survey has indicated a significant potential risk for the general population. To obtain a wide-spread source for latex exposure, we have considered tire debris. We have searched for the presence of latex allergens in passenger car and truck tire tread, in debris deposited from the atmosphere near a freeway, and in airborne particulate matter samples representative of the entire year 1993 at two sites in the Los Angeles basin (California). After extraction of the samples with phosphate buffered saline, a modified-ELISA inhibition assay was used to measure relative allergen potency and Western blot analyses were used to identify latex allergens. The inhibition studies with the human IgE latex assay revealed inhibition by the tire tread source samples and ambient freeway dust, as well as by control latex sap and latex glove extracts. Levels of extractable latex allergen per unit of protein extracted were about two orders of magnitude lower for tire tread as compared to latex gloves. Western blot analyses using binding of human IgE from latex-sensitive patients showed a band at 34-36 kDa in all tire and ambient samples. Long Beach and Los Angeles, California, air samples showed four additional bands between 50 and 135 kDa. Alternative Western blot analyses using rabbit IgG raised against latex proteins showed a broad band at 30-50 kDa in all samples, with additional bands in the urban air samples similar to the IgE results. A latex cross-reactive material was identified in mountain cedar. In conclusion, the latex allergens or latex cross-reactive material present in sedimented and airborne particulate material, derived from tire debris, and generated by heavy urban vehicle traffic could be important factors in producing latex allergy

  7. Latex allergens in tire dust and airborne particles.

    PubMed

    Miguel, A G; Cass, G R; Weiss, J; Glovsky, M M

    1996-11-01

    The prevalence and severity of latex allergy has increased dramatically in the last 15 years due to exposure to natural rubber products. Although historically this health risk has been elevated in hospital personnel and patients, a recent survey has indicated a significant potential risk for the general population. To obtain a wide-spread source for latex exposure, we have considered tire debris. We have searched for the presence of latex allergens in passenger car and truck tire tread, in debris deposited from the atmosphere near a freeway, and in airborne particulate matter samples representative of the entire year 1993 at two sites in the Los Angeles basin (California). After extraction of the samples with phosphate buffered saline, a modified-ELISA inhibition assay was used to measure relative allergen potency and Western blot analyses were used to identify latex allergens. The inhibition studies with the human IgE latex assay revealed inhibition by the tire tread source samples and ambient freeway dust, as well as by control latex sap and latex glove extracts. Levels of extractable latex allergen per unit of protein extracted were about two orders of magnitude lower for tire tread as compared to latex gloves. Western blot analyses using binding of human IgE from latex-sensitive patients showed a band at 34-36 kDa in all tire and ambient samples. Long Beach and Los Angeles, California, air samples showed four additional bands between 50 and 135 kDa. Alternative Western blot analyses using rabbit IgG raised against latex proteins showed a broad band at 30-50 kDa in all samples, with additional bands in the urban air samples similar to the IgE results. A latex cross-reactive material was identified in mountain cedar. In conclusion, the latex allergens or latex cross-reactive material present in sedimented and airborne particulate material, derived from tire debris, and generated by heavy urban vehicle traffic could be important factors in producing latex allergy

  8. Blends of guayule natural rubber latex with commercial latex polymers

    USDA-ARS?s Scientific Manuscript database

    Guayule (Parthenium argentatum) is a woody desert shrub that produces natural rubber, cis-1,4 polyisoprene, by biosynthesis. It is currently cultivated in the southwestern United States as a source of latex and rubber for commercial development. Guayule latex is similar to Hevea latex in polymer mo...

  9. 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.

  10. 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 ...

  11. Latex allergies - for hospital patients

    MedlinePlus

    ... Allergy Association; American College of Allergy, Asthma and Immunology. Guidelines for the Management of Latex Allergies. Updated 2016. latexallergyresources.org/articles/guidelines-management-latex-allergies . Accessed April 7, 2016.

  12. 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

  13. Interaction of bacterial endotoxine (lipopolysaccharide) with latex particles: application to latex agglutination immunoassays.

    PubMed

    Peula-García, J M; Molina-Bolivar, J A; Velasco, J; Rojas, A; Galisteo-González, F

    2002-01-15

    The latex agglutination immunoassay technique uses polymer colloids as carriers for antibodies or antigens to enhance the immunological reaction. In this work, the interaction of a lipopolysaccharide (LPS) of Brucella Melitensis with two conventional latexes has been studied. Some experiments on the physical adsorption of the LPS onto these polystyrene beads have been performed and several complexes with different coverage degrees were obtained by modifying the incubation conditions. Regarding the application in the development of diagnostic test systems, it is advisable to study the latex-LPS complexes from an electrokinetic and colloidal stability point of view. The complexes were electrokinetically characterized by measuring the electrophoretic mobility under different redispersion conditions. The colloidal stability was determined by simple turbidity measurements. Experimental and theoretical data have been employed to study the molecular disposition of the LPS in the latex particle surface to compare with the outer membrane of bacterial cells. Latex complexes covered by different LPS amounts showed high colloidal stability and adequate immunoreactivity that remains for a long time period.

  14. 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.

  15. 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.

  16. Nursing students with latex allergy.

    PubMed

    Katrancha, Elizabeth D; Harshberger, Lorri A

    2012-11-01

    Latex allergy affects millions of people in the general population and a higher percentage of health care workers. Nursing students with a latex sensitivity pose a unique challenge for the nurse educator. Students may enter the program with pre-existing latex allergy or develop the allergy during the educational process. This manuscript explores the implications of latex allergies exhibited by the nursing student. It addresses the responsibilities of the educator in the skills or simulation laboratory and during clinical learning experiences. It also offers suggestions for ensuring the safety of the student while reducing the legal liabilities of the educational program. The article addresses possible policy ramifications for nursing schools.

  17. 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,…

  18. Latex Allergy: Tips to Remember

    MedlinePlus

    ... itself. If you have an allergy, your immune system identifies something that is typically harmless as an invader or allergen. With latex allergy, it overreacts by producing antibodies called Immunoglobulin E (IgE) that can react with contaminating proteins found in the natural rubber latex. These ...

  19. 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.

  20. Modifiers for Asphalt Concrete

    DTIC Science & Technology

    1990-11-01

    approximately correct for bituminous mixtures, where the particulate character and granular nature of the material is wc1- r1czsognized. Earlier work on fiber...still exist; however, these correlations could be improved if the appropriate constitutive law is utilized. Advances in the fields of material ...development of constitutive relationships that better replicate material responses such as viscoelasticity and vis- coplasticity (i.e., viscous elastic-plastic

  1. 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}.

  2. [Latex allergy--Part I].

    PubMed

    Chełmińska, Marta

    2004-01-01

    Natural rubber latex (NRL), is a resin sap produced in the cells of caoutchouc plants. It is a water dispersion of cis-1,4-polisopren (caoutchouc)--35%, stabilized with little amounts of proteins, sugar, alcohol, fatty acids and salts. The concentration of all solid substances is about 40%, the rest is water. Immunogenicity of latex depends on the proteins it contains. For many years we read in medical papers about the cases of contact urticaria, asthma, rhinitis, and anaphylaxis after contacting with latex products. It turns out that medical staff is the group of high occupational risk, because of exposure to gloves and other latex products. It is connected with the fact of high gloves usage caused by the danger of virus infections: HIV, HBV, HCV. Latex allergy is one of the reasons of dramatic complications after surgical operations. People who are allergic to latex may have cross reactions to allergens not connected with occupational environment. These are: food and houseplants (Ficus benjamina). The frequency of latex allergy is about 0.1% of the population. In the groups of high risk the frequency rises sharply. It is 17% among medical staff and it reaches 60% among children with spina bifida.

  3. 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 Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Latex-Dipped, Latex-Extruded, and Latex-Molded Rubber Subcategory §...

  4. 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 §...

  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, 2011 CFR

    2011-07-01

    ... 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 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, 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 §...

  8. Making Latex Microspheres in Space

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Equipment yields larger, more uniform particles. Two NASA reports describe first commercial product to be manufactured in space. Product monodisperse latex, suspension of spherical particles of essentially same diameter. Carried aboard Space Shuttle on its orbital missions, monodisperse latex reactor (MLR) produces spheres of much larger size than possible on Earth. Mircospheres 30 micrometers in diameter produced, whereas 5 micrometers is limit for Earthbound reactors. Microspheres as large as 100 micrometers scheduled for production in MLR.

  9. Latex allergy: a nursing update.

    PubMed

    Kramper, M A

    2000-01-01

    Latex allergy emerged in the 1990's as a significant and challenging public health concern for patients as well as healthcare workers. This article provides a review of this complex health care challenge. Understanding latex allergy production and sources of exposure will provide a background to explore the immunological implications of this exposure risk. Diagnostic and treatment measures are reviewed. The focus of this article is to increase awareness and encourage prevention of this growing health concern.

  10. Making Latex Microspheres in Space

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Equipment yields larger, more uniform particles. Two NASA reports describe first commercial product to be manufactured in space. Product monodisperse latex, suspension of spherical particles of essentially same diameter. Carried aboard Space Shuttle on its orbital missions, monodisperse latex reactor (MLR) produces spheres of much larger size than possible on Earth. Mircospheres 30 micrometers in diameter produced, whereas 5 micrometers is limit for Earthbound reactors. Microspheres as large as 100 micrometers scheduled for production in MLR.

  11. Modeling of pervaporation with latex membranes

    SciTech Connect

    Huang, R.Y.M.; Wei, Y. )

    1994-06-01

    Latex membranes have shown potential to be a new type of pervaporation separation membrane. Three types of latex membranes were prepared in our laboratory by direct casting of polymer latexes. These latex membranes were selective toward water during pervaporation with ethanol-water mixtures. The free-volume approach was employed to characterize the pervaporation of these latex membranes. It is shown by this experiment that the Yeom-Huang model, which is based on the free-volume theory and the thermodynamics, can be used to model the pervaporation process of the latex membranes which give reasonable predictions on the permeability. 18 refs., 3 figs., 8 tabs.

  12. The latex story.

    PubMed

    Raulf, Monika

    2014-01-01

    The milky sap of the rubber tree Hevea brasiliensis is the source of the commercial production of natural rubber latex (NRL) devices, and also represents a source of potent allergenic proteins. NRL materials were introduced in the health care field in about 1840 with the advent of technical abilities to produce suitable and flexible NRL materials for medical products, especially gloves. In the late 1980s, with the increase of transmittable diseases, particularly HIV infection, the use of NRL gloves increased dramatically. During the 1990s, NRL emerged as a major cause of clinically relevant allergy in health care workers using NRL gloves and spina bifida patients with operation on the first day. The increased recognition of NRL allergies, the enhanced research on allergen characterization and sensitization mechanisms, and education about this allergy in health care facilities combined with the introduction of powder-free gloves with reduced protein levels are all factors associated with a decline in the number of suspected cases of NRL allergies in the late 1990s. NRL allergy is a very good example of a 'new allergy' that suddenly arises with tremendous health and economic implications, and also of an allergy which becomes history in a relatively short period of time based on successful primary prevention strategies by strict allergen avoidance. © 2014 S. Karger AG, Basel.

  13. Supporting Concrete Visual Thinking in Multiplicative Reasoning: Difficulties and Opportunities.

    ERIC Educational Resources Information Center

    Kaput, James J.

    1989-01-01

    Describes environments for concretely enacting multiplication and division. Discusses difficulties occurring when students use one of the concrete environments to model situations involving modified environments. (YP)

  14. Synthesis and characterization of polymer-silica hybrid latexes and sol-gel-derived films

    NASA Astrophysics Data System (ADS)

    Petcu, Cristian; Purcar, Violeta; Ianchiş, Raluca; Spătaru, Cătălin-Ilie; Ghiurea, Marius; Nicolae, Cristian Andi; Stroescu, Hermine; Atanase, Leonard-Ionuţ; Frone, Adriana Nicoleta; Trică, Bogdan; Donescu, Dan

    2016-12-01

    Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Sisbnd Osbnd Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

  15. EVALUATION OF LOW-VOC LATEX PAINTS

    EPA Science Inventory

    The paper gives results of an evaluation of four commercially available low-VOC (volatile organic compound) latex paints as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that ...

  16. EVALUATION OF LOW-VOC LATEX PAINTS

    EPA Science Inventory

    The paper gives results of an evaluation of four commercially available low-VOC (volatile organic compound) latex paints as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that ...

  17. Non-latex versus latex male condoms for contraception.

    PubMed

    Gallo, M F; Grimes, D A; Lopez, L M; Schulz, K F

    2006-01-25

    The male condom, which consists of a thin sheath placed over the glans and shaft of the penis, is designed to prevent pregnancy by providing a physical barrier against the deposition of semen into the vagina during intercourse. Beginning in the 1990s, nonlatex male condoms made of polyurethane film or synthetic elastomers were developed as alternative male barrier methods for individuals with allergies, sensitivities or preferences that prevented the consistent use of condoms made of latex. The review sought to evaluate nonlatex male condoms in comparison with latex condoms in terms of contraceptive efficacy, breakage and slippage, safety, and user preferences. We searched computerized databases for randomized controlled trials of nonlatex condoms. We also wrote to the manufacturers of nonlatex condoms and known investigators in an attempt to locate any other trials not identified in our search. The review included all randomized controlled trials identified in the literature search that evaluated a male nonlatex condom made of polyurethane film or synthetic elastomers in comparison with a latex condom. We evaluated all titles and abstracts located in the literature searches for inclusion. Two authors independently extracted data from the identified studies. We analyzed data with RevMan. The Peto odds ratio (Peto OR) with 95% confidence interval (CI) was calculated for each outcome of contraceptive efficacy, condom breakage and slippage, discontinuation of use, safety, and user preference. Contraceptive efficacy, early discontinuation, and safety outcomes were also measured with survival analysis techniques. While the eZ.on condom did not protect against pregnancy as well as its latex comparison condom, no differences were found in the typical-use efficacy between the Avanti and the Standard Tactylon and their latex counterparts. The nonlatex condoms had significantly higher rates of clinical breakage than their latex comparison condoms: the Peto OR for clinical

  18. Latex allergy in women's health care.

    PubMed

    Fletcher, Joanne

    2013-01-01

    Latex allergy in midwifery and women's health care is not a new concept, with numerous case reports documenting adverse reactions in pregnant women to natural rubber latex in the birthing room. The practising midwife, nurse and sonographer need to be aware of the signs and symptoms of latex allergy and the implications of a severe reaction to latex not only to the woman but also the unborn child.

  19. Film formation from latex blends

    NASA Astrophysics Data System (ADS)

    Tang, Jiansheng

    2000-10-01

    Film formation from hard/soft (i.e., high Tg/low Tg) latex blends consisting of hard polystyrene (PS) and soft poly(n-butyl methacrylate-co-n-butyl acrylate) [P(BMA/BA)] latex particles were studied with an emphasis on the influence of the carboxyl groups present on the latex particles. A theoretical model was developed to calculate the optimal surfactant and monomer feed rates for a semicontinuous polymerization process to synthesize monodisperse carboxylated latex particles and independently control the particle size and degree of carboxylation. An important finding obtained from the drying studies is that the drying rate from the edge zone is much faster than the rate obtained from the latex pool. It was also found that the presence of carboxyl groups on the latex particles retarded the drying rate. Utilizing PS particles with a low density of carboxyl groups present on the particle surfaces (e.g., 10% surface coverage) resulted in an even distribution of these particles in the soft copolymer matrix, and thus, good film gloss was achieved. However, the use of hard particles with a high density of carboxyl groups present (e.g., 65% coverage) resulted in a less even distribution of PS particles and poor gloss. A cluster model and a hydrogen bonding mechanism were proposed to explain these phenomena. The presence of the carboxyl groups on the PS particles significantly enhanced the Young's modulus and the yield strength, but did not influence the ultimate mechanical properties. A quantitative model was proposed to predict the Young's modus of the latex blend films as a function of the carboxyl group coverage on the hard particles. There was a good fit between model and the experimental data. The stability of the precipitated calcium carbonate (PCC) particles in the P(BMA/BA) latexes was determined by the charge on pigment surface which, in turn, was influenced by the presence of sodium polyacrylate stabilizer. It was found that the wetting ability of the soft

  20. Integration of latex protein sequence data provides comprehensive functional overview of latex proteins.

    PubMed

    Cho, Won Kyong; Jo, Yeonhwa; Chu, Hyosub; Park, Sang-Ho; Kim, Kook-Hyung

    2014-03-01

    The laticiferous system is one of the most important conduit systems in higher plants, which produces a milky-like sap known as latex. Latex contains diverse secondary metabolites with various ecological functions. To obtain a comprehensive overview of the latex proteome, we integrated available latex proteins sequences and constructed a comprehensive dataset composed of 1,208 non-redundant latex proteins from 20 various latex-bearing plants. The results of functional analyses revealed that latex proteins are involved in various biological processes, including transcription, translation, protein degradation and the plant response to environmental stimuli. The results of the comparative analysis showed that the functions of the latex proteins are similar to those of phloem, suggesting the functional conservation of plant vascular proteins. The presence of latex proteins in mitochondria and plastids suggests the production of diverse secondary metabolites. Furthermore, using a BLAST search, we identified 854 homologous latex proteins in eight plant species, including three latex-bearing plants, such as papaya, caster bean and cassava, suggesting that latex proteins were newly evolved in vascular plants. Taken together, this study is the largest and most comprehensive in silico analysis of the latex proteome. The results obtained here provide useful resources and information for characterizing the evolution of the latex proteome.

  1. Scanning electron microscopic examination of human pulmonary capillaries using a latex replication method.

    PubMed

    Kendall, M W; Eissmann, E

    1980-03-01

    The human pulmonary microvasculature from the apical bronchopulmonary segment was studied by scanning electron microscopy using latex replicas. The latex replica was composed of a blend of vinyl chloride latexes using a plasticized vinyl chloride copolymer with a vinyl chloride copolymer. The polymerized latex produced a cast of the pulmonary arterial vascular tree, including the capillary patterns, which freely anastomose, thereby draining blood into pulmonary veinules and veins. The latex was injected via a gravity flow system modified from its earlier application in Guinea pig lungs. The apparently normal lungs from two recently deceased humans (dead for 5-6 hours and held in refrigeration) were perfused with heparinized Ringer's solution and subsequently injected with latex. The resulting latex casts of the capillaries revealed a three-dimensional network arranged in irregular vascular rings or ovals. This pattern was most conspicuous in deep and intermediate bronchopulmonary segmental areas. However, the subpleural capillaries produced casts that often terminated blindly, as observed with stereo SEm, suggesting that these vessels may tend to form thrombi more easily as compared with capillaries from other regions of the lung alveoli. The pulmonary arteriolar replicas contained indentations representing endothelial cell nuclei, and the capillary replicas projected oval evaginations that may represent discrete loci or capillary mural attenuations.

  2. Non-latex versus latex male condoms for contraception.

    PubMed

    Gallo, M F; Grimes, D A; Schulz, K F

    2003-01-01

    The male condom, which consists of a thin sheath placed over the glans and shaft of the penis, is designed to prevent pregnancy by providing a physical barrier against the deposition of semen into the vagina during intercourse. Beginning in the 1990s, nonlatex male condoms made of polyurethane film or synthetic elastomers were developed as alternative male barrier methods for individuals with allergies, sensitivities or preferences that prevented the consistent use of condoms made of latex. The review sought to evaluate nonlatex male condoms in comparison with latex condoms in terms of contraceptive efficacy, breakage, slippage, safety and user preferences. We searched the the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE using PubMed, EMBASE, Popline, and LILACS for randomized controlled trials of nonlatex condoms. The references of eligible publications were assessed for inclusion. We also wrote to the manufacturers of nonlatex condoms and known investigators in an attempt to locate any other published or unpublished trials not identified in our search. The review included all randomized controlled trials identified in the literature search that evaluated a male nonlatex condom made of polyurethane film or synthetic elastomers in comparison with a latex condom. We evaluated all titles and abstracts located in the literature searches for inclusion in the review. Two reviewers independently extracted data from the identified studies. We entered and analyzed data with RevMan 4.1. Peto odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for the outcomes contraceptive efficacy, condom breakage and slippage, discontinuation of use, safety and user preference. The number of condoms, men, or women was used as the denominator for the ORs. Contraceptive efficacy, early discontinuation, and safety outcomes were also measured with survival analysis techniques and entered into "Additional tables." While the eZ.on condom did not protect

  3. 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}.

  4. Effect of field natural rubber latex with different ammonia contents and storage period on physical properties of latex concentrate, stability of skim latex and dipped film

    NASA Astrophysics Data System (ADS)

    Santipanusopon, Sirinapa; Riyajan, Sa-Ad

    2009-07-01

    The effect of ammonia treatment in field natural rubber (NR) latex with different storage period time on the properties of concentrated NR latex and stability of skim latex was investigated. Fresh NR latex was treated with various ammonia contents such as 0.35, 0.60 and 0.80% w/w, and then they were centrifuged to get the concentrated NR latex with 60% dry rubber content (DRC) containing 0.16, 0.18 and 0.25% w/w, respectively and skim NR latex with roughly 5% DRC containing 0.42, 0.60 and 0.80% w/w, respectively. The effect of storage times with ∼0, 15, 30 and 45 days for concentrated NR latex with different ammonia contents on their properties such as alkalinity, magnesium content and viscosity was observed. It was found that generally, magnesium content in field NR latex and latex concentrate decreased with storage period times. The alkalinity content in both concentrated NR and skim latex increased with increasing ammonia content in field latex. The viscosity of concentrated NR latex increased as a function of storage period time of field NR latex. The stability of skim latex depends on storage period time of field NR latex with different ammonias. The tensile strength of dipped films obtained from field NR latex with 0.80% w/w of ammonia was dependent on storage period time of field NR latex.

  5. Allergenic proteins of natural rubber latex.

    PubMed

    Yeang, H Y; Arif, Siti Arija M; Yusof, Faridah; Sunderasan, E

    2002-05-01

    As the living cytoplasm of laticiferous cells, Hevea brasiliensis latex is a rich blend of organic substances that include a mélange of proteins. A small number of these proteins have given rise to the problem of latex allergy. The salient characteristics of H. brasiliensis latex allergens that are recognized by the International Union of Immunological Societies (IUIS) are reviewed. These are the proteins associated with the rubber particles, the cytosolic C-serum proteins and the B-serum proteins that originate mainly from the lutoids. Procedures for the isolation and purification of latex allergens are discussed, from latex collection in the field to various preparative approaches adopted in the laboratory. As interest in recombinant latex allergens increases, there is a need to validate recombinant proteins to ascertain equivalence with their native counterparts when used in immunological studies, diagnostics, and immunotherapy.

  6. Cathodic protection of steel reinforced concrete facilitated by using carbon fiber reinforced mortar or concrete

    SciTech Connect

    Hou, J.; Chung, D.D.L.

    1997-05-01

    Due to the decrease in volume electrical resistivity associated with carbon fiber addition (0.35 vol.%) to concrete (embedding steel rebar), concrete containing carbon fibers and silica fume reduced by 18% the driving voltage required for cathodic protection compared to plain concrete, and by 28% compared to concrete with silica fume. Due to the decrease in resistivity associated with carbon fiber addition (1.1 vol.%) to mortar, overlay (embedding titanium wires for electrical contacts to steel reinforced concrete) in the form of mortar containing carbon fibers and latex reduced by the 10% the driving voltage required for cathodic protection, compared to plain mortar overlay. In spite of the low resistivity of mortar overlay with carbon fibers, cathodic protection required multiple metal electrical contacts embedded in the mortar at a spacing of 11 cm or less.

  7. Producing Large-Particle Monodisperse Latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.

    1986-01-01

    Chemical process produces latex particles of relatively large, uniform size for use as size standards for instrument calibration. Process, based on seeding of mixture by very small latex particles, yields particles measuring 2 to 30 micrometer or more in average size. Produces monodisperse latexes in which deviation from average size is less than 2 percent. Particles used directly, without tedious separation procedures for removing off-size particles.

  8. Microgravity and the Formation of Latex Spheres

    NASA Technical Reports Server (NTRS)

    1982-01-01

    This set of photographs illustrates the value of microgravity in the formation of latex spheres. The image at left shows irregular spheres produced on Earth, while the photograph at right shows uniform spheres produced during the STS-3 mission, March 22 - 30, 1982, in the Monodisperse Latex Reactor, developed by the Marshall Space Flight Center and Lehigh University. The Marshall-managed MLR experiment demonstrated the feasibility of producing monodisperse polystyrene latex microspheres in space and their application to medicine and industry.

  9. Microgravity and the Formation of Latex Spheres

    NASA Technical Reports Server (NTRS)

    1982-01-01

    This set of photographs illustrates the value of microgravity in the formation of latex spheres. The image at left shows irregular spheres produced on Earth, while the photograph at right shows uniform spheres produced during the STS-3 mission, March 22 - 30, 1982, in the Monodisperse Latex Reactor, developed by the Marshall Space Flight Center and Lehigh University. The Marshall-managed MLR experiment demonstrated the feasibility of producing monodisperse polystyrene latex microspheres in space and their application to medicine and industry.

  10. Producing Large-Particle Monodisperse Latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.

    1986-01-01

    Chemical process produces latex particles of relatively large, uniform size for use as size standards for instrument calibration. Process, based on seeding of mixture by very small latex particles, yields particles measuring 2 to 30 micrometer or more in average size. Produces monodisperse latexes in which deviation from average size is less than 2 percent. Particles used directly, without tedious separation procedures for removing off-size particles.

  11. In vitro properties' changes of latex and non-latex orthodontic elastics.

    PubMed

    Bertoncini, Chiara; Cioni, Erica; Grampi, Barbara; Gandini, Paola

    2006-01-01

    The purpose of this study is to evaluate the effectiveness of non-latex elastics regarding their use in clinical practice for latex-intolerant individuals. In this study, 80 latex and 80 non-latex elastics produced by Leone S.p.A. were divided into 4 groups of 20 elastics each. They were submitted to traction tests after being placed in Ringer's solution for different periods of time. Force loss and permanent deformation (considered as the difference between the initial and final diameter) was then determined in order to evaluate the behaviour of each elastic after every test. The variation of force was calculated using the Instron Machine, while the profile projector was used to measure the elastics' diameter. The latex elastics undergo less loss of force than the non latex elastics. The difference between the two tested samples becomes significant after 24 hours. Regarding the variation of the inner diameter, in every test, non-latex elastics showed a more significant deformation than latex ones and the difference was significant. When compared to latex elastics, non-latex elastics showed a greater deformation of the inner diameter and the forces generated in Ringer's solution are significantly less after 24 hours. To conclude, latex-free elastics are suitable for orthodontic treatment in patients with allergies, although further study to investigate the dynamic behaviour of latex- free elastics.

  12. Effect of gilsonite-modified asphalt on hot-mix asphaltic concrete mixes used in District 12, Houston, Texas

    SciTech Connect

    Wong, C.; Ho, M.K.

    1990-06-01

    Gilsonite is a naturally occurring black hydrocarbon from Utah with a high asphaltene content and an unusual amount of nitrogen compounds. Because of its composition, it is believed that the addition of gilsonite will increase the viscosity, stability, water susceptibility and durability of the asphalt mix. The District 12 laboratory conducted tests on two hot mix designs using gilsonite-modified asphalts. A control batch and batches containing 4%, 6% and 8% gilsonite by weight of asphalt were tested. The appropriate gilsonite-aggregate mixtures were molded and evaluated for stability, specific gravity, indirect tensile strength and water susceptibility. From the results of the laboratory tests, it was evident that gilsonite-modified asphalt mixes did increase dry and wet tensile strength but did not increase H veem stability. Since there is no overwhelming proof of gilsonite's ability as an anti-stripping agent, it has been recommended that gilsonite be used with an anti-stripping agent to combat stripping and rutting. It is further recommended that the field performance of gilsonite be evaluated before approval is given for its use.

  13. Rotary Reactor Makes Large Latex Particles

    NASA Technical Reports Server (NTRS)

    Kornfeld, Dale M.

    1988-01-01

    Machine reduces gravitational effects interfering with particle growth. Reaction chamber rotates while polymerization of latex proceeds. Motor turns stirrer. Chamber made of stainless steel with glass windows.

  14. 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.

  15. Rotary Reactor Makes Large Latex Particles

    NASA Technical Reports Server (NTRS)

    Kornfeld, Dale M.

    1988-01-01

    Machine reduces gravitational effects interfering with particle growth. Reaction chamber rotates while polymerization of latex proceeds. Motor turns stirrer. Chamber made of stainless steel with glass windows.

  16. Development of a crumb rubber modified (CRM) asphalt concrete mix design. Final report, June 1993-May 1995

    SciTech Connect

    Hossain, M.; Swartz, S.E.; Hoque, M.E.; Funk, L.P.

    1995-05-01

    The objective of this project was to develop an asphalt mix design method incorporating crumb rubber and using the `Wet` or `Dry` method of producing Crumb Rubber Modified Asphalt (CRM). Several resurfacing projects have been constructed using both the `Wet` and `Dry` methods. Based on this study, KDOT could use CRM mixes with a binder content between 7.5% and 9.0% depending on the percent air voids, with 19% to 22% rubber content. In this study, it was observed that using 24% rubber produced mixed were too sticky to manage. With a rubber content of less than 18% combined with AC-5 it was difficult to satisfy the minimum requirements. Fracture tests can be used as a basis to determine the optimum binder content for any asphalt-rubber mix.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  19. 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)

  20. Detection of cytomegalovirus antibody with latex agglutination.

    PubMed Central

    Adler, S P; McVoy, M; Biro, V G; Britt, W J; Hider, P; Marshall, D

    1985-01-01

    Transfusion-acquired cytomegalovirus (CMV) infections should be prevented in seronegative immunocompromised patients by providing blood products from donors who are also seronegative. Latex agglutination was investigated as a simple and rapid method for detecting antibody against CMV. Latex beads were coated with CMV antigen, incubated for 8 min at room temperature with 25 microliter of sera, and examined for agglutination. The sensitivity and specificity of latex agglutination was compared with that of indirect hemagglutination (IHA, Cetus Corp., Emeryville, Calif.) and enzyme immunoassay (EIA) with sera from 604 random blood donors or patients. Of 327 serum samples shown to be seronegative by EIA and IHA, 327 had a latex agglutination titer of less than 1:4 (specificity, 100%). Of 236 serum samples with detectable antibody by EIA and IHA, 228 had a latex agglutination titer of 1:4 or greater (sensitivity, 97%). Plasma collected with EDTA, heparin, or citrate was satisfactory for latex agglutination. Latex agglutination results correlated quantitatively with those of EIA, and the test also detected fourfold or greater rises in antibody with paired sera from six patients with posttransfusion CMV infections. Latex agglutination is a sensitive and specific assay that is rapid and simple to perform and should be effective in selecting seronegative blood donors to prevent posttransfusion CMV infections in seronegative recipients. PMID:2991330

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Reinforcement of latex rubber by the incorporation of amphiphilic nanoparticles

    USDA-ARS?s Scientific Manuscript database

    Latex rubbers are fabricated from latex suspensions. During the fabrication process, latex particles are bound together while water is removed from the suspension. This report shows the mechanical properties of latex rubbers can be improved by incorporating a small amount of amphiphilic nanoparticle...

  8. Latex allergies in the health care worker.

    PubMed

    Tesiorowski, Caroline C

    2003-02-01

    A dramatic increase in the incidence of latex allergies in health care workers followed the surge in latex glove use accompanying the rise of human immunodeficiency virus (HIV) in the early 1980s. This increase in latex glove use was driven by the release of Universal Precautions issued by the Centers for Disease Control (CDC) in response to the rise of HIV and other blood-borne pathogens. Efforts to stem allergic responses in the workplace have relied on the substitution of other materials for latex. Unfortunately, there is so much latex in everyday life that avoiding this allergen is exceedingly difficult once one is sensitized. Additionally, there are numerous cross reactants that are present in the environment. The situation is further confounded by the introduction of genetically manipulated foods and agricultural products that contain defense proteins genetically inserted to protect plants from pests and pathogens. Many of these defense proteins are antigens that will cross react with latex. Sensitivity reactions, once developed, may progress to the point at which the health care worker is excluded from working. This report provides an overview of rubber products and cross reactants, allergic reactions, and latex sensitivity for the health care worker. Copyright 2003 by American Society of PeriAnesthesia Nurses.

  9. Evaluation of low-VOC latex paints

    SciTech Connect

    Chang, J.C.S.; Fortmann, R.C.; Roache, N.F.; Lao, H.C.

    1999-01-01

    The paper gives results of an evaluation of four commercially available low-VOC (volatile organic compound) latex paints as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that the VOC contents of all four paints are considerably lower than those of conventional latex paints. Low-VOC emissions were confirmed by small chamber emission tests. However, sigificant emissions of several aldehydes, especially formaldehyde, were detected from two of the paints. ASTM methods were used to evaluate the hiding power, scrubbability, washability, dry to touch, and yellowing index. The results indicated that one of the low-VOC paints tested showed performance equivalent or superior to that of a widely used conventional latex paint used as a control. It was concluded that low-VOC latex paint can be a viable option to replace conventional latex paints for prevention of indoor air pollution. However, paints marketed as low-VOC may still have significant emissions of some individual VOCs, and some may not have performance characteristics matching those of conventional latex paints.

  10. Evaluation of low-VOC latex paints

    SciTech Connect

    Chang, J.C.S.; Fortmann, R.C.; Roache, N.F.; Lao, H.C.

    1999-11-01

    The paper gives results of an evaluation of four commercially available low-VOC (volatile organic compound) latex paints as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that the VOC contents of all four paints are considerably lower than those of conventional latex paints. Low-VOC emissions were confirmed by small chamber emission tests. However, sigificant emissions of several aldehydes, especially formaldehyde, were detected from two of the paints. ASTM methods were used to evaluate the hiding power, scrubbability, washability, dry to touch, and yellowing index. The results indicated that one of the low-VOC paints tested showed performance equivalent or superior to that of a widely used conventional latex paint used as a control. It was concluded that low-VOC latex paint can be a viable option to replace conventional latex paints for prevention of indoor air pollution. However, paints marketed as low-VOC may still have significant emissions of some individual VOCs, and some may not have performance characteristics matching those of conventional latex paints.

  11. [Latex allergy in a population at risk].

    PubMed

    Ruiz Fernández, M; Flores Sandoval, G; Orea Solano, M

    1999-01-01

    The allergy to latex is an illness whose prevalence has been increased in very significant form in the last years. To know the allergy incidence to latex in population of risk, as well as to identify the related sintomatology and the importance or paper that play the atopia antecedents and time of contact with latex for the development of the illness. We carry out a prospective, descriptive, experimental and traverse study in population of risk, in the service of Allergy and clinical Immunology of the Hospital Regional Lic. Adolfo López Mateos, ISSSTE. One hundred patients of both sexes were included, with age of 20 to 50 years, with the antecedent of being personal medical and paramedic and to have presented contact with latex material in a minimum period of one year. They were carried out clinical history with registration of sintomatology nasal, bronchial, cutaneous and associated to contact with latex. They were carried out cutaneous test for prick to latex with positive control with the help of histamine solution and negative control with solution of Evans and immediate reading of the same one. 22% of the patients in study, they presented positive skin test latex, with a time of exhibition 10 year-old average, 68% presented antecedent of atopy personal, family and, likewise the associate sintomatology was in a 33.3% dermatology, 54.5 nasal, nobody presented bronchial symptoms and a 9% asymptomatic was reported. We support that the immediate skin test latex for Prick is an important parameter of support diagnosis for allergy to type 1 latex.

  12. Concrete Durability: A Multibillion-Dollar Opportunity

    DTIC Science & Technology

    1987-01-01

    Fum -Containing Products 79 MDF Materials 85 Fiber-Reinforced Materials 85 Modified - Sulfur Concretes 87 References 88 APPENDIX: BIOGRAPHICAL SKETCHES...construction. MODIFIED - SULFUR CONCRETES Molten sulfur-sand grouts have been used for many years in the constructLin of acid vats because of their

  13. RED2TEX: A TRIX RED to LATEX converter

    SciTech Connect

    Chase, L.; Langdon, A.B.

    1987-05-20

    A summary of RED2TEX is presented. RED2TEX converts standard TRIX RED format commands to TEX or LATEX commands for subsequent LATEX formatting. LATEX is a special version of the TEX document preparation system. LATEX adds to TEX a collection of commands that simplifies formatting. LATEX runs on the J-Vax and the LLL-LCC Pyramid machines. RED2TEX resides in Unix directory CHASE/TEX.

  14. 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.

  15. Cytotoxicity of latex and non-latex orthodontic elastomeric ligatures on L929 mouse fibroblasts.

    PubMed

    Santos, Rogério Lacerda dos; Pithon, Matheus Melo; Martins, Fernanda Otaviano; Romanos, Maria Teresa Villela; Ruellas, Antônio Carlos de Oliveira

    2010-01-01

    This study investigated the cytotoxicity exists between latex and non-latex Orthodontic elastomeric ligatures. Six elastomeric ligatures (1 latex, 2 latex-free and 3 polyurethane) from different manufacturers were divided into 6 groups of 15 elastics each: A (Latex-free, American Orthodontics), M (Polyurethane, Morelli), G (Polyurethane,GAC International), Te (Polyurethane, Tecnident), TP (Natural latex,TP Orthodontics) and U (Latex-free,3M Unitek). The cytotoxicity assay was performed using cell cultures (L929 mouse fibroblast cell line), which were subjected to the cell viability test with neutral red ("dye-uptake") at 1, 2, 3, 7 and 28 days. Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). No statistically significant differences (p>0.05) were observed between Groups M and Te in all experimental periods, except at 2 days. No significant differences (p>0.05) in cell viability were found either among Groups A, G, TP and U or between Groups M and Te at 24 h or among Groups CC, A, G, TP and U at 2 and 28 days. It may be concluded that latex-free elastomeric ligatures from American Orthodontics and Unitek trademarks induced less cell lysis compared to latex and polyurethane ligatures.

  16. [Prevalence of latex hypersensitivity among medical personnel].

    PubMed

    Camacho Ibarra, V C; López García, A I; Galindo García, J A; Paz Martínez, D; Papaqui Tapia, J S

    1997-01-01

    In order to determine the latex hypersensitivity prevalence in medical residents from Hospital Universitario de Puebla, it was carried out a transversal, observational and descriptive study including the medical staff of all specialties. The epicutancous test was effectuated with 1:20 latex antigen dilution. It was studied a total of 90 medical residents, 68.9% were males and 31.1% females. The mean age was 30.6 years (SD 3.8). The 50% were from clinical specialties and 50% else were from surgical. The global latex hypersensitivity prevalence was 8%. It will be convenient to carry out a follow up of studied cohort to establish if continual exposition, years later, will determine skin reactivity to latex in professional practice.

  17. [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.

  18. Characterisation of the rubber elongation factor from ammoniated latex by electrophoresis and mass spectrometry.

    PubMed

    Dürauer, A; Csaszar, E; Mechtler, K; Jungbauer, A; Schmid, E

    2000-08-18

    Rubber elongation factor (REF) is considered as one of the major allergens present in latex. An extraction and purification protocol for preparation of REF standards has been modified. A protein fraction was extracted from ammoniated latex sap and purified by gel filtration chromatography. The purified and concentrated proteins were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis into two major bands. These bands were further characterised by matrix-assisted laser desorption/ionisation time-of-flight and nano-electrospray ionization mass spectrometry. REF and a truncated form could be ascertained by the mass and fragmentation pattern of the tryptic peptides. In the faster migrating band an additional peptide could be identified. This peptide is also present in Hevb3 and a Mr 27000 latex allergen. Our findings indicate that conventional REF preparations as standards may contain additional allergenic proteins.

  19. PREPACKED CONCRETE.

    DTIC Science & Technology

    Twenty four hardened plain concrete wallettes , each 31 in. high by 25 in. wide by 6 in. thick, were sawed into various rectangular parallelepipeds...The wallettes represented three groups of prepacked concrete: reference aggregate intruded with fresh-water grout, coral aggregate with fresh-water...prismatic test specimens were involved in the program for determining the effectsof: type of mixing water, type of wiremesh cover atop the wallette form

  20. Vascular permeability, neutrophil migration and edematogenic effects induced by the latex of Cryptostegia grandiflora.

    PubMed

    Albuquerque, Tatiana M; Alencar, Nylane M N; Figueiredo, Jozi G; Figueiredo, Ingrid S T; Teixeira, Cinthia M; Bitencourt, Flávio S; Secco, Daniela D; Araújo, Eliane S; Ana Maria Leão, C A; Ramos, Márcio V

    2009-01-01

    Inflammatory responses have been described as occurring after exposure to some latex materials. In this study pro-inflammatory activity in the latex of Cryptostegia grandiflora was investigated. The soluble proteins of the latex (CgLP) were isolated from the whole latex and evaluated by in vivo assays. CgLP induced strong inflammatory activity mediated by neutrophil migration, enlarging vascular permeability and increasing myeloperoxidase activity locally in rats. CgLP-induced inflammation was observed in peritonitis, paw edema and air push models. In addition, CgLP caused hyperemia in a healing model. The peritonitis effect was lost when CgLP was previously boiled suggesting the involvement of pro-inflammatory proteins. Thioglycollate increased the neutrophil migration induced by CgLP, but not by fMLP. Mast cell depletion provoked by 40/80 compound did not modify the course of inflammation triggered by CgLP, being similar to fMLP, which suggested that neutrophil migration was induced by direct mechanism mediated by macrophages. Neutrophil migration stimulated by CgLP was strongly inhibited by Dexamethasone and to a lesser extent by Thalidomide, indicating the involvement of cytokines in mediating neutrophil infiltration. Celecoxib and Indomethacin were inhibitory suggesting the involvement of prostaglandins. Cimetidine was effective only in the initial phase of edema. PCA 4248 was ineffective. It is concluded that the latex of C. grandiflora is a potent inflammatory fluid, and also that laticifer proteins may be implicated in this process.

  1. 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.

  2. In vitro study of force decay of latex and non-latex orthodontic elastics.

    PubMed

    López, Noelia; Vicente, Ascensión; Bravo, Luis A; Calvo, José L; Canteras, Manuel

    2012-04-01

    The aim of this study was to evaluate the force decay of two brands of orthodontic elastics, both offering latex and non-latex products. Samples were subjected to continuous stretching, measuring force at 5 seconds, 8 hours, and 24 hours in both dry and wet conditions. Five hundred samples were used, GAC® and Lancer® 0.25 inch and 4 oz, divided into testing sample sizes of n = 25 per group. For the dry test, elastics were kept stretched to three times their internal diameter for 5 seconds (initial force), 8 hours, and 24 hours; for the wet test, they were stretched for 8 and 24 hours. Both brands showed initial forces significantly greater than those specified by the manufacturers (P < 0.05). Comparing wet/dry conditions, there was a greater force loss in the wet medium than the dry. As for elastic composition (latex or non-latex), the only significant difference found was between Lancer elastics with and without latex in dry conditions, force loss being greater for latex-free elastics. Comparing brands, there was greater force loss with GAC than with Lancer. Comparing elastic force at the eight-hour mark and the twenty-four hour mark to the initial force (only in wet conditions), GAC latex and non-latex and Lancer latex elastics showed significantly less force at eight and twenty four hours than initially. On the other hand, Lancer non-latex was the only type of elastics that did not show a significant decrease in its initial elastic characteristics at eight hours in wet conditions. Nevertheless, Lancer non-latex did show significantly less force in wet conditions at twenty four-hours than the forces observed initially and at eight-hours.

  3. Mechanical Force Sensitive Acrylic Latex Coating.

    PubMed

    Li, Meng; Liu, Weifeng; Zhang, Qi; Zhu, Shiping

    2017-05-03

    We prepared force sensitive acrylic latex coatings by covalently incorporating spiropyran mechanophore. The acrylic latexes were obtained through emulsion copolymerization of butyl acrylate (BA), methyl methacrylate (MMA) with vinyltriethoxysilane (VTES) as interparticle cross-linker, and (1'-(2-(methacryloyloxy)ethyl)-3',3'-dimethylspiro[chromene-2,2'-indolin]-6-yl)methyl methacrylate) (SP) as intraparticle cross-linker. The latexes of P(BA-co-MMA-co-SP-co-VTES) were subsequently cast onto Teflon-coated surface to form latex coatings. The condensation of hydrolyzed VTES provided interparticle cross-linking and improved mechanical properties of the formed thin films. Intraparticle cross-linker SP endowed the coatings with mechanoreponsiveness. The mechanoactivation of SP-containing latex films was demonstrated. Increasing the content of intra-cross-linker SP resulted in higher stress sensitivity and lower critical stress required for mechanoactivation. Increasing the content of interparticle cross-linker VTES resulted in higher critical stress for SP mechanoactivation but had little effect on the stress sensitivity. Tg and operation temperature also showed significant effect on mechanoactivation. Slower strain rate allowed for higher SP-to-MC conversion. This work represents the first example of mechanochromic acrylic latexes and provides insight into the design of force sensitive and self-reporting polymer coatings.

  4. Quality of life in health care workers with latex allergy.

    PubMed

    Power, Susan; Gallagher, John; Meaney, Sarah

    2010-01-01

    Exposure to latex gloves and glove powder makes health care workers (HCWs) particularly susceptible to developing an allergy to latex. To assess the impact on the quality of life (QOL) of HCWs who are allergic to latex products before removal from latex exposure and after removal from exposure. We studied 39 latex allergic HCWs from the Health & Safety Executive south area. Twenty-nine attended for an assessment with the occupational physician and were asked to fill out a questionnaire. Spirometry, immunoglobulin E levels and latex radioallergosorbent test levels were measured. In total, 29/39 (74%) of patients responded. All of the participants had a type 1 allergy to latex. All individuals reported a significant improvement of symptoms once latex was removed from their working environment. Of those that reported skin complaints, 83% reported that their skin no longer had an impact on their QOL once latex was removed. Over 90% (n = 26) of all participants stated that their eye/nose symptoms had no longer an impact on their QOL and 86% (n = 25) of all participants stated that their respiratory symptoms had no impact on their QOL following the removal of latex from their working environment. Overall, 45% of the respondents had changed jobs: 61% of this group changed to a completely nonclinical post. On average, 86% of latex allergic HCWs reported that their QOL had improved significantly since their removal from latex. In employees who are latex allergic/sensitized, taking latex avoidance measures results in cessation or diminution of symptoms.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Characterization of copolymer latexes by capillary electrophoresis.

    PubMed

    Anik, Nadia; Airiau, Marc; Labeau, Marie-Pierre; Bzducha, Wojciech; Cottet, Hervé

    2010-02-02

    Latexes are widely used for industrial applications, including decorative paints, binders for the papermaking industry, and drilling fluids for oil-field applications. In this work, the interest of capillary zone electrophoresis (CE) for the characterization of hydrophobic block copolymer latexes obtained by the conventional emulsion polymerization technique consisting of a core of polystyrene (PS) surrounded by a layer of poly(ethyl acrylate) (PEA) has been investigated. The PEA part of the copolymer can be partially hydrolyzed in poly(acrylic acid) (PAA) leading to PS-PEA-AA water-soluble amphiphilic copolymer having high viscosifying properties. The main purpose of this work was to evaluate the potential of CE for the characterization of the latexes at the different stages of the synthesis (PS core, PS-PEA diblock latex, and hydrolyzed PS-PEA-AA gel). The main analytical issues were to state (i) if there was free PS or PEA homopolymer latexes in the PS-PEA latex sample and (ii) if there was free PS, PEA, PS-PEA latexes, or free PAA chains in the PS-PEA-AA gel. Within this scope, this work describes the optimization of the selectivity of the separation between the different species (PS, PEA particles in the not hydrolyzed diblock latex and PS, PEA, PS-PEA particles as well as the polymer PAA chains in the PS-PEA-AA diblock gel sample obtained by latter latex hydrolysis). For that purpose, several experimental parameters were investigated such as pH and ionic strength of the background electrolyte (BGE) or the concentration of neutral surfactant added in the BGE. A challenging issue was to overcome the high viscosity of the PS-PEA-AA gel. This was resolved by the addition of 10 mM neutral surfactant in the gel sample and in the BGE. Finally, it is demonstrated that, within the detection limits, CE is a suitable analytical tool for controlling and monitoring the syntheses of these latexes and for intrinsically characterizing the distribution in charge density of

  11. Acceptability evaluation of a natural rubber latex, a polyurethane, and a new non-latex condom.

    PubMed

    Frezieres, R G; Walsh, T L

    2000-06-01

    After more than a century of reliance on latex condoms, male condoms fabricated from new materials are finally becoming commercially available to consumers. This study was an open label acceptability study that compared three lubricated condom products during vaginal intercourse: a natural rubber latex condom, a polyurethane condom, and a new non-latex (styrene ethylene butylene styrene, SEBS) condom. Fifty-four couples who were using condoms for birth control were enrolled in this three-way crossover study. Each couple tested three condoms of each type in a randomized sequence. Couples reported condom performance after each use and rated condom acceptability after use of three condoms of each type. At the completion of the study, participants selected their preferred condom type for overall acceptability, sensitivity, ease of use, appearance, and comfort. All three condom types had low clinical breakage and slippage rates (latex 37%, polyurethane 24%, new non-latex (SEBS) 37%, no preference 2%; females: natural rubber latex 33%, polyurethane 27%, new non-latex 37%, no preference 2%]. A statistically higher proportion of couples preferred both the natural rubber latex condom and the new non-latex condom above the polyurethane condom for ease of unrolling, and the natural rubber latex condom above the other condom types for perceived safety. Approximately two-thirds of both male and female participants preferred one of the two condoms made of synthetic materials suggesting that consumers will appreciate the availability of these products.

  12. Is latex surface charge an important parameter for foam stabilization?

    PubMed

    Kettlewell, Sarah L; Schmid, Andreas; Fujii, Syuji; Dupin, Damien; Armes, Steven P

    2007-11-06

    We describe the facile production of highly stable foams stabilized solely by cationic polystyrene latex particles. Three model polystyrene latexes were synthesized using either a cationic 2,2'-azobis(2-diisobutyramidine) dihydrochloride (AIBA) or an anionic ammonium persulfate (APS) radical initiator: a 724 +/- 81 nm charge-stabilized cationic polystyrene latex [AIBA-PS], an 800 +/- 138 nm sterically stabilized cationic latex prepared using a poly(ethylene glycol) monomethacrylate macromonomer [PEGMA-AIBA-PS], and a 904 +/- 131 nm charge-stabilized anionic polystyrene latex [APS-PS], respectively. The effect of particle surface charge, latex concentration, and solution pH on foam stability was studied in detail. The PEGMA-AIBA-PS latex proved to be the best foam stabilizer even at relatively low latex concentrations (3.0 wt %), with long-term foam stabilities being obtained after drying. The AIBA-PS latex also produced stable foams, albeit only at higher latex concentrations. However, the APS-PS latex proved to be an ineffective foam stabilizer. This is believed to be primarily due to the anionic surface character of this latter latex, which prevents its adsorption at the anionic air-water interface. This hypothesis is supported by the observation that the AIBA-PS latex no longer acts as an effective foam stabilizer above its isoelectric point (pH 7.04). Scanning electron microscopy studies revealed the formation of well-defined latex bilayers within dried foams, which indicates that the wet air bubbles are stabilized by latex monolayers prior to drying. However, little or no long-range ordering of the latex particles was observed on the surface of the bubbles, which is presumably related to the latex polydispersity.

  13. Aqueous particulate foams stabilized solely with polymer latex particles.

    PubMed

    Fujii, S; Iddon, P D; Ryan, A J; Armes, S P

    2006-08-29

    In this article, a wide range of latexes are evaluated as possible foam stabilizers. These include near-monodisperse, poly(N-vinyl pyrrolidone)-stabilized polystyrene [PNVP-PS] latexes with diameters ranging from 170 nm to 1.62 microm, submicrometer-sized poly(ethylene glycol)-stabilized polystyrene [PEGMA-PS] latex particles, a PNVP-stabilized poly(4-bromostyrene) [PNVP-PBrS] latex with a mean diameter of 870 nm, two PNVP-stabilized poly(methyl methacrylate) [PNVP-PMMA] latexes with mean diameters of 730 nm and 1.20 microm, a PNVP-stabilized poly(2-hydroxypropyl methacrylate) [PNVP-PHPMA] latex with a mean diameter of 630 nm, and a charge-stabilized anionic PS latex of 220 nm diameter. The effect of varying the particle size, latex concentration, and latex surface composition on foam stability were studied in detail. The larger PNVP-PS latexes, the PNVP-PBrS, and the two PNVP-PMMA latexes gave highly stable foams, whereas PEGMA-PS, PNVP-PHPMA, and the charge-stabilized PS latex produced either no foams or foams with inferior long-term stabilities. Scanning electron microscopy studies revealed hexagonally close-packed latex arrays in the walls of the dried foam, which leads to localized moiré patterns being observed by optical microscopy. Moreover, these dried foams are highly iridescent in bright transmitted light.

  14. Low prevalence of latex allergy in children with spinal dysraphism in non-latex-free environment.

    PubMed

    Goldberg, Hanan; Aharony, Shachar; Levy, Yael; Sivan, Bezalel; Baniel, Jack; Ben Meir, David

    2016-02-01

    Studies in the past have shown that children with spinal dysraphism have highly prevalent latex allergy. These children have a spectrum of congenital spinal anomalies, caused by defects in neural tube closure, with an incidence of 1 in 1000 births. Proposed risk factors for latex allergy include multiple surgeries since birth, including an insertion of a ventriculoperitoneal shunt, elevated IgE titers, repeat multiple catheterizations, and atopy. In the 1990 s, studies published in the United States and Europe showed a latex allergy prevalence of over 70% in these patients. On the other hand, studies published years later in other countries showed a declining prevalence of no more than 17%. Our goal was to prospectively assess the prevalence of latex allergy in children with spinal dysraphism in our non-latex free environment center compared with a control group. The study group included 58 children with spinal dysraphism attending our center between 2010 and 2013. Findings were compared to 65 children referred for evaluation of allergic diseases. The parents completed questionnaires assessing personal and familial history of allergic diseases. All children were tested for blood latex IgE-specific antibodies (IMMULITE 2000). The mean age was 120.9 (67.6) months in the study group and 129.5 (68.5) months in the control group (p = 0.27). The corresponding median number of surgical procedures was 2 (range 0-10) and 0 (range 0-4), and mean duration of clean intermittent catheterization was 52 (72.2) months in the study group. Positive IgE antibodies and clinical allergic reactions were low with very similar prevalence in both groups (Figure). Our results show considerable lower latex allergy and sensitization than studies published in the United States and Europe in the past, despite the fact that our center utilizes minimal avoidance measures for latex allergy. Study limitations include the relatively small number of patients in our single-center study. Moreover, our

  15. 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.

  16. 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.

  17. Anticonvulsant action of Calotropis procera latex proteins.

    PubMed

    Lima, Raquel Cristina de Sousa; Silva, Márcia Calheiros Chaves; Aguiar, Carlos Clayton Torres; Chaves, Edna Maria Camelo; Dias, Kátia Cilene Ferreira; Macêdo, Danielle Silveira; de Sousa, Francisca Cléa Florenço; Carvalho, Krishnamurti de Morais; Ramos, Márcio Viana; Vasconcelos, Silvânia Maria Mendes

    2012-02-01

    Calotropis procera (Ait.) R.Br. is a laticiferous plant belonging to the Apocynaceae family. C. procera latex proteins were evaluated with respect to anticonvulsant and sedative activity in mouse models of pentylenetetrazol (PTZ)-, pilocarpine-, and strychnine-induced convulsions or turning behavior and pentobarbital-induced sleep. In the strychnine- and pilocarpine-induced seizure models, C. procera latex proteins caused no significant alterations in latencies to convulsions and death, as compared with controls. In the PTZ-induced seizure model, administration of C. procera latex proteins in high doses (50 or 100mg/kg) and diazepam caused significant increases in latencies to convulsions and death. C. procera latex proteins (50 or 100mg/kg) and 2mg/kg diazepam caused a decrease in sleep latency and an increase in sleep time compared with the control group and groups treated with 5 or 10mg/kg. Our results suggest that C. procera latex proteins have a central nervous system-depressant activity as reflected in their potentiation of pentobarbital-induced sleeping time and their anticonvulsant action in the PTZ-induced seizure model. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. 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.

  19. Hypersensitivity to latex and Ficus benjamina allergens.

    PubMed

    Delbourg, M F; Moneret-Vautrin, D A; Guilloux, L; Ville, G

    1995-12-01

    Association between allergy to Ficus benjamina and Hevea brasiliensis, two botanically unrelated plants, was suspected in consequence of two clinical observations. Symptoms were rhinitis and asthma. This study was undertaken to assess the in vivo and in vitro cross-reactivity between Ficus benjamina and Hevea brasiliensis allergens. The two patients were asked about use and contact with latex devices and relationship between symptoms and Ficus benjamina exposure. Skin prick tests were performed with Ficus benjamina, Hevea brasiliensis extracts and common allergens. Double-blind nasal and bronchial challenge tests were done using the rinse fluid from a brand of latex gloves. Total and specific IgE antibodies to Ficus benjamina and Hevea brasiliensis were determined. In vitro cross-reactivity was investigated by means of CAP RAST and immunodot inhibition experiments. We observed that for the first patient the primary phenomenon is probably allergy to latex followed by allergy to Ficus benjamina. For the second patient, allergy to Ficus benjamina was diagnosed (improvement related to the avoidance of exposure to Ficus benjamina allergens) and positivity to latex skin prick tests may be due to the cross-reacting allergens. In vitro assays showed specific IgE antibodies to both allergens and cross-reactivity was confirmed in the two cases by reciprocal inhibition of the two extracts. The increasing risk of sensitization to widely used latex devices and extensive exposure to Ficus species in households and offices indicates increased allergenic risk from this newly recognized cross-reactivity.

  20. 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.

  1. Protein and allergen content of various natural latex articles.

    PubMed

    Baur, X; Chen, Z; Raulf-Heimsoth, M; Degens, P

    1997-06-01

    Proteins remaining in products made of natural rubber latex are potential sensitizers. In the present work, we quantified the releasable protein and allergen contents in 37 brands of latex gloves and 26 other latex products. Our results demonstrate the presence of widely varied protein and allergen contents in various latex articles and the lack of a correlation between the protein and allergen values. These findings may assist hospital management and medical staff to take effective preventive measures.

  2. [Anaphylactic manifestations during protected sexual intercourse disclosing allergy to latex].

    PubMed

    Espin, M; Didier, A; Perez, T; Carre, P; Leophonte, P

    1991-01-01

    Reports of allergy to latex have been increasingly frequent during the last few years. The culprit is the natural Hevea Brasiliensis latex which is present in numerous latex-containing materials for daily use. Clinical manifestations are usually benign. Systemic manifestations have been reported mainly in general anaesthesia. We report a case of severe anaphylactic manifestations that occurred during a condom-protected sexual intercourse. The responsibility of latex for this accident was demonstrated by skin and biological tests.

  3. [Latex agglutination test in amebic liver abscess].

    PubMed

    Gómez Maganda y Silva, T; García Carrizosa, R; Torres Valadez, F; Ortiz Ramírez, E; Villaseñor de la Parra, C; Flores González, A; Gómez García, E

    1978-01-01

    Amebic hepatic abscesses are one of the most frequent and serious complications of intestinal amibiasis. Although many methods exists with which the diagnosis can be made, frequently problems do arise. Serologic reactions play an important role in the diagnosis of amebic hepatic abscess. Among the most useful of the serological tests, is that which evaluates agglutination with latex particles. Latex agglutination was positive in 98.5% of 200 cases of proved amebic hepatic abscess. The pros and cons of the utility of this test compared with other serological tests are discussed. It is concluded that or the especialist as well as the general practicioner latex agglutination can be extremely useful in the diagnosis of amebic hepatic abscess.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  5. 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.

  6. LaTeX for Agricultural Extension Professionals

    USDA-ARS?s Scientific Manuscript database

    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. Latex of immunodiagnosis for detecting the Chagas disease. I. Synthesis of the base carboxylated latex.

    PubMed

    Gonzalez, Verónica D G; Gugliotta, Luis M; Meira, Gregorio R

    2008-02-01

    This article investigates the synthesis of two (monodisperse, carboxylated, and core-shell) latexes, through a batch and a semibatch emulsion copolymerizations of styrene (St) and methacrylic acid (MAA) onto polystyrene latex seeds. A mathematical model of the process was developed that predicts conversion, average particle size, and surface density of carboxyl groups. The model was adjusted to the batch reaction measurements, and then it was used in the design of the semibatch experiment. The semibatch reaction involved an initial homopolymerization of St followed by instantaneous addition of MAA-St-initiator. Compared with the batch reaction results, the semibatch policy more than doubled the surface density of carboxyl groups. The second part of this series describes the development of an immunodiagnosis latex-protein complex for detecting the Chagas disease, by coupling an antigen of Trypanosoma cruzi onto the produced carboxylated latexes.

  8. Latex anaphylaxis caused by a Swan-Ganz catheter.

    PubMed

    Sekiya, Kiyoshi; Watai, Kentaro; Taniguchi, Masami; Mitsui, Chihiro; Fukutomi, Yuma; Tanimoto, Hidenori; Kawaura, Noriyuki; Akiyama, Kazuo

    2011-01-01

    A 78-year-old woman visited the division of cardiovascular disease in our hospital. She underwent a cardiac catheter examination, and a Swan-Ganz catheter was inserted. Several minutes later, she developed anaphylactic shock. She had no past history of latex allergy, but did have a banana allergy. Skin prick tests showed a positive reaction to an extract of latex gloves and an extract of the balloon of a Swan-Ganz catheter. Anaphylactic shock caused by the latex balloon of a Swan-Ganz catheter was diagnosed. It is necessary to pay attention to not only latex allergy but also fruit allergies with a cross-reactivity to latex.

  9. kxp and kxpl: A busy man's LaTeX

    SciTech Connect

    Kwong, Man Kam.

    1991-03-01

    This report introduces the following programs: kxp: a time-saving LaTeX preprocessor, kxpl: kxp plus latex, kxh: a help facility for kxp and LaTex, ptex: a program for printing a LaTeX document, and pptex: a program for printing parts of a LaTeX document. More detailed descriptions will be given in Part 2: A Reference Manual. The appendix gives instructions on how to use Argonne's Mathematics and Computer Science Division letterhead and intralaboratory memo L{sup A}T{sub E}X styles.

  10. Polymer interdiffusion and mechanical property development during latex film formation

    SciTech Connect

    Fu, Z.; Boczar, E.M.; Kirk, A.B.

    1995-12-31

    The interdiffusion of polymer chains across the latex boundaries during latex film formation has been studied using the fluorescence technique of direct energy transfer (DET) or small-angle neutron scattering technique (SANS) by several groups. The increase in mechanical strength and the interdiffusion depth determined by SANS has been correlated for several polystyrene latex systems during film formation. In this paper, we will present the correlation between the increase in mechanical strength and the interdiffusion depth for a poly (amyl methacrylate) latex system. Volume fractions of mixing (Fm) as a function of annealing time for two poly (amyl methacrylate) latex blend films were measured.

  11. Type I allergies to latex and the aeroallergenic problem.

    PubMed

    Heese, A; Peters, K P; Koch, H U

    1997-01-01

    Between 1989 and 1995, a 12-fold increase in latex allergy was documented amongst our patients. Similar findings have been noted elsewhere. Increase in type I allergies to latex has become an international problem. The issues associated with latex allergy are described, including those posed by the ubiquitous nature of latex in medical equipment, and in commonplace domestic objects. The potential for allergic patients to cross react to a variety of fruits or plants is an added problem for sensitized patients. This paper concludes that the universal introduction of powder-free surgical gloves with low protein content would be a very important measure in the prevention of acquired latex allergy.

  12. Development and investigation of a selective latex flocculant

    SciTech Connect

    Nikitin, I.N.; Preobrazhenskii, B.P.; Tsyrlov, M.Ya.; Plastovets, I.K.; Litmanovich, I.M.; Tikhonova, O.F.

    1982-01-01

    Investigations were made on the use of two synthetic latexes as selective flocculants in the flotation cleaning of coal. The most commonly used latex in the industry contained sodium dibutylnaphthalenesulfonate, which is a biologically ''hard'' emulsifier. It was determined that butadiene-styrene latexes may successfully be used as selective coal sludge flocculants. The most efficient was a latex synthesized using biodegradable emulsifiers--potassium soaps of disproportionated rosin with a small quantity of synthetic fatty acids. Also, it was concluded that the values of the ash level in the flotation concentrate and tailings could be controlled by regulating the latex consumption.

  13. Radiation-induced vulcanisation of natural rubber latex in presence of styrene-butadiene rubber latex

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Bhardwaj, Y. K.; Patil, N. D.; Dubey, K. A.; Kumar, Virendra; Sabharwal, S.

    2005-04-01

    Radiation vulcanisation of natural rubber latex in presence of styrene butadiene rubber latex (SBRL) has been investigated. The cast films were characterised for their swelling properties, tensile strength and thermal stability as a function of radiation dose as well as SBRL content. The gel content, tensile strength and thermal stability of the copolymer films were found to increase with increasing the SBRL content in the feed solution and radiation dose.

  14. Cement and Concrete Nanoscience and Nanotechnology

    PubMed Central

    Raki, Laila; Beaudoin, James; Alizadeh, Rouhollah; Makar, Jon; Sato, Taijiro

    2010-01-01

    Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. Recent work at the National Research Council Canada in the area of concrete materials research has shown the potential of improving concrete properties by modifying the structure of cement hydrates, addition of nanoparticles and nanotubes and controlling the delivery of admixtures. This article will focus on a review of these innovative achievements.

  15. Film formation and paper coating with poly ([beta]-hydroxyalkanoate), a biodegradable latex

    SciTech Connect

    Lauzier, C.A.; Monasterios, C.J.; Saracovan, I.; Marchessault, R.H. ); Ramsay, B.A. )

    1993-05-01

    An aqueous latex of a poly ([beta]-hydroxyalkanoate) (PHA) coated on paper imparted water imperviousness without changing mechanical properties. Hot-pressed films biodegraded faster than solvent cast films. The PHA coating on paper degraded totally in activated sludge within 12 days, leaving the cellulose matrix relatively untouched. Blends of PHA latexes with sodium carboxymethl cellulose, polystyrene latex, carboxylated styrenel butadiene latex, natural rubber latex, carboxylated styrenel butadiene latex; natural rubber latex, and starch powders form satisfactory films at room temperature.

  16. Case report of latex aerosolization from a transesophageal echocardiogram machine.

    PubMed

    Muller, Barbara A; Steelman, Victoria J

    2004-01-01

    Aerosolized natural rubber latex proteins produce latex sensitization and can cause acute allergic reactions in susceptible individuals. The objective of this study is to describe measures that should be taken to ensure a latex-safe hospital environment. A case of latex-induced anaphylaxis prompted a survey of air quality in acute care areas of a major tertiary health care center that had eliminated the use of powder-free latex gloves years earlier. Six air samples were collected using pre- and postcalibrated sampling pumps operating at 2.7 L/minute. Samples were collected in duplicate on three-piece 37-mm Teflon filters in open-faced cassettes and tested for latex allergen by inhibition immunoassay. All samples had less than the detection limit > 5 ng/m3 for aerosolized latex except for the echocardiogram suite where the transesophageal echocardiogram machine was located. After thorough cleaning of the suite and echocardiogram machine, subsequent air sampling showed no detectable latex aerosolization particles. Follow-up investigation to discover the source of contamination revealed that the department performing routine maintenance on the echocardiogram equipment used powdered latex gloves obtained outside the hospital. Employees who are latex allergic may experience symptoms even in an environment of powder-free, nonlatex gloves. The site was a contaminated transesophageal echocardiogram machine. Institutional policies should be in place to monitor employee complaints and address allergic reactions to latex.

  17. 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.

  18. Electrical-conductivity testing of latex gloves

    SciTech Connect

    Stampfer, J.F.; Salazar, J.A.; Trujillo, A.G.; Harris, T.; Berardinelli, S.P.

    1994-11-01

    There is an increasing awareness in the healthcare field that gloves worn for protection from hazards associated with body fluids do not always afford the protection desired. Gloves may have defects, such as holes, as they come from the manufacturer or distributor, or they may become defective during storage or use. While the numbers vary widely, failure rates for new gloves, defined as detectable holes in gloves prior to use, for unused examination gloves are reported as high as 58%. Rates as high as 7% have been reported for sterile latex gloves. Incidences of breaching the latex barrier during use vary with procedure but have been reported as high as 50%. In recent years, a number of devices have been developed to detect holes in latex gloves as they are being worn. Detection of increased electrical conductivity that takes place through the holes in the gloves is used to activate an audible alarm. The primary purpose of this research was to investigate the validity of this method for hole detection. This evaluation was accomplished with both basic laboratory equipment and commercially available instruments. We did not evaluate or critically compare the individual devices. We also investigated the use of electrical conductivity as a quality assurance (QA) procedure, and the degradation of latex gloves due to storage and exposure to laboratory atmospheres and disinfectants.

  19. Determination of zinc dialkyldithiocarbamates in latex condoms.

    PubMed

    Depree, G J; Bledsoe, T A; Siegel, P D

    2004-02-01

    A simple high-performance liquid chromatographic (HPLC) assay is developed for measuring zinc dialkyldithiocarbamate (DTC) levels in latex condoms. After extraction of 14 different brands of latex condoms in acetonitrile, aliquots of the extracts are subjected to a preliminary screening assay by treatment with cobalt chloride and measurement of UV absorption at 320 nm, which results in the identification of 6 DTC-containing samples. Prior to analysis by HPLC, zinc dimethyldithiocarbamate (ZDMC) or zinc diethyldithiocarbamate (ZDEC) is added to the extracts in order to block transmetalation reactions with the analytes of interest. A reversed-phase C(18) column, with gradient elution and UV detection at 260 nm, is used to measure the zinc DTCs. The limits of detection for ZDEC and zinc dibutyldithiocarbamate (ZDBC) are 5 and 10 micro g/mL. Levels of ZDBC and ZDEC range from not detectable to 3.31 and 1.79 mg/condom, respectively. Total protein and latex allergenic protein levels are determined and range from 98 to 776 and 0.01 to 14.04 micro g/unit, respectively, but are not related to the level of ZDBC or ZDEC. This methodology provides both screening and specific tools for the determination of unstable zinc DTC complexes in latex products.

  20. From polymer latexes to multifunctional liquid marbles.

    PubMed

    Fernandes, Ana M; Mantione, Daniele; Gracia, Raquel; Leiza, Jose R; Paulis, Maria; Mecerreyes, David

    2015-02-25

    A simple method to prepare multifunctional liquid marbles and dry water with magnetic, color, and fluorescent properties is presented. Multifunctional liquid marbles were prepared by encapsulation of water droplets using flocculated polymer latexes. First, the emulsion polymerization reaction of polystyrene and poly(benzyl methacrylate) was carried out using cheap and commercially available cationic surfactants. Subsequently, flocculation of the latex was provoked by an anion-exchange reaction of the cationic surfactant by the addition of lithium bis(trifluoromethanesulfonyl)imide salt. The flocculated polymer latex was filtered and dried, leading to very hydrophobic micronanoparticulated powders. These powders showed a great ability to stabilize the air/water interface. Stable liquid marbles were obtained by rolling water droplets onto the hydrophobic powders previously prepared. The use of very small polystyrene nanoparticles led us to the preparation of very stable and the biggest known liquid marbles up to 2.5 mL of water. Furthermore, the introduction of fluorescent comonomer dyes into the polymer powders allowed us to obtain new morphological images and new knowledge about the structure of liquid marbles by confocal microscopy. Furthermore, the introduction of magnetic nanoparticles into the polymer latex led to magnetic responsive liquid marbles, where the iron oxide nanoparticles are protected within a polymer. Altogether this method represents an accessible and general platform for the preparation of multifunctional liquid marbles and dry water, which may contribute to extending of their actual range of applications.

  1. Selective sorption of latex membranes with ethanol-water mixtures

    SciTech Connect

    Wei, Y.; Huang, R.Y.M. )

    1994-02-01

    Latex membranes have recently found use in pervaporation separation. The sorption of water-ethanol mixtures to latex membranes was carried out on three types of latex membranes, poly(acrylonitrile-co-butyl acrylate) [P(AN-BuA)], poly(methyl methacrylate-co-butyl acrylate) [P(MMA-BuA)], and poly(styrene-co-butyl acrylate) [P(ST-BuA)], which were prepared in our laboratory by direct casting of polymer latexes synthesized by emulsion polymerization. These latex membranes all exhibit preferential sorption and permeation toward water. Both water and ethanol sorption to the latex membranes exhibited nonideal sorption, with water sorption being enhanced greatly by the presence of ethanol. It was shown that the solubility parameter theory did not give correct predictions for the preferential sorption of latex membranes. Better results were obtained by using the Flory-Huggins interaction parameter. 12 refs., 4 figs., 2 tabs.

  2. Function of fibrinogen gamma-chain dodecapeptide-conjugated latex beads under flow.

    PubMed

    Takeoka, Shinji; Okamura, Yosuke; Teramura, Yuji; Watanabe, Naohide; Suzuki, Hidenori; Tsuchida, Eishun; Handa, Makoto; Ikeda, Yasuo

    2003-12-19

    In order to perform a fundamental study of platelet substitutes, novel particles that bound to activated platelets were prepared using two oligopeptides conjugated to latex beads. The oligopeptides were CHHLGGAKQAGDV (H12), which is a fibrinogen gamma-chain carboxy-terminal sequence (gamma 400-411), and CGGRGDF (RGD), which contains a fibrinogen alpha-chain sequence (alpha 95-98 RGDF). Both peptides contained an additional amino-terminal cysteine to enable conjugation. Human serum albumin was adsorbed onto the surface of latex beads (average diameter 1microm) and pyridyldisulfide groups were chemically introduced into the adsorbed protein. H12 or RGD peptides were then chemically linked to the modified surface protein via disulfide linkages. H12- or RGD-conjugated latex beads prepared in this way enhanced the in vitro thrombus formation of activated platelets on collagen-immobilized plates under flowing thrombocytopenic-imitation blood. Based on the result of flow cytometric analyses of agglutination, PAC-1 binding, antiP-selectin antibody binding, and annexin V binding, the H12-conjugated latex beads showed minimal interaction with non-activated platelets. These results indicate the excellent potential of H12-conjugated particles as a candidate for a platelet substitute.

  3. 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.

  4. Medical devices manufactured from latex: European regulatory initiatives.

    PubMed

    De Jong, W H; Geertsma, R E; Tinkler, J J B

    2002-05-01

    In Europe the marketing of medical devices manufactured from latex is regulated by directives describing the essential (safety) requirements that products have to fulfill to obtain marketing approval. This paper describes the general requirements for marketing medical devices in Europe and, more specifically, the requirements for products manufactured from natural rubber latex. The requirements for marketing medical devices can be fulfilled by using the relevant harmonized European standards. These standards are regularly under revision to incorporate the latest scientific developments. For certain devices, for example, latex medical (examination and surgical) gloves, specific standards have been published. Medical devices manufactured from latex pose a serious problem because of the risk of induction of allergy both against the latex proteins inherently present (type I or immediate type allergy) and against chemicals added during processing (type IV or delayed type hypersensitivity) present as residues in the latex products. So, besides requirements for product quality in terms of barrier properties, strength, and sterility, the main focus consists of the allergy-inducing properties of the latex products. Recent developments have reopened the discussion on the value of total protein versus allergen determination in latex medical gloves. However, as long as minimal levels needed for both sensitization and elicitation have not been established, a safe maximum level for leachable proteins/allergens in latex products cannot be determined. A European Commission guidance document on the latex allergy problem is currently being drafted by experts from Competent Authorities.

  5. 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.

  6. 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.

  7. Latex migration in battery slurries during drying.

    PubMed

    Lim, Sanghyuk; Ahn, Kyung Hyun; Yamamura, Masato

    2013-07-02

    We used real-time fluorescence microscopy to investigate the migration of latex particles in drying battery slurries. The time evolution of the fluorescence signals revealed that the migration of the latex particles was suppressed above the entanglement concentration of carboxymethyl cellulose (CMC), while it was significantly enhanced when CMC fully covered the surfaces of the graphite particles. In particular, a two-step migration was observed when the graphite particles flocculated by depletion attraction at high CMC/graphite mass ratios. The transient states of the nonadsorbing CMC and graphite particles in a medium were discussed, and the uses of this novel measurement technique to monitor the complex drying processes of films were demonstrated.

  8. Identification and practical management of latex allergy in occupational settings.

    PubMed

    Caballero, María Luisa; Quirce, Santiago

    2015-01-01

    Allergy to natural rubber latex (NRL) from Hevea brasiliensis is a relevant occupational health hazard. The use of gloves and products manufactured with latex and environmental allergen exposure in the work environment are risks factors for the development of occupational allergy among different job categories. Healthcare workers have been the most commonly affected, but other professions with exposure to latex products such as hairdressers, cleaners, food handlers and those making natural rubber latex (NRL) products are also at risk of developing occupational allergy. Clinical manifestations of IgE-mediated latex allergy can range from troublesome skin disorders to life-threatening systemic reactions. It is very important to identify the occupational allergic diseases in their early stages in order to implement avoidance strategies. For this purpose, the interventions for prevention should emphasize the importance of latex allergy awareness and surveillance among exposed workforces.

  9. Metabolic changes in Euphorbia palusrtis latex after fungal infection.

    PubMed

    Krstić, Gordana; Anđelković, Boban; Choi, Young Hae; Vajs, Vlatka; Stević, Tatjana; Tešević, Vele; Gođevac, Dejan

    2016-11-01

    The variations of metabolic profile of the latex of wild-growing Euphorbia palustris was carried out using multivariate analysis of (1)H NMR spectral data. One population was infected with fungi Fusarium sporotrichioides, Fusarium proliferatum and Alternaria alternata, while the other consisted of healthy plant species. The non-polar metabolites of latex extracts such as benzoyl ingenol-laurate, amyrin decadienoate esters, cis-1,4-polyisoprene, and 24-methylenecycloartanol were identified using (1)H and 2D NMR spectra. Principal component analysis of (1)H NMR data provided a clear discrimination between the latex of infected and healthy plants. Minimum inhibitory concentration and minimum fungicidal concentration values of the latex extracts of healthy and infected plants were determined. The latex of infected plants was found to contain higher levels of benzoyl ingenol-laurate and 24-methylenecycloartanol, of which concentrations were strongly correlated with the antifungal activities of the latex. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Occupational asthma due to latex in health care workers.

    PubMed Central

    Ho, A.; Chan, H.; Tse, K. S.; Chan-Yeung, M.

    1996-01-01

    Immediate hypersensitivity reactions ranging from mild urticaria to life threatening anaphylaxis after exposure to natural rubber latex have been reported frequently in health care workers while occupational asthma due to latex exposure is less well studied. The results of specific challenge tests and immunological tests in four health care workers with work related respiratory and skin disorders induced by the use of latex gloves are described. Occupational asthma was confirmed in three subjects by specific challenge tests. All had a positive skin test reaction to the latex extract; specific IgE antibodies were detected in only one subject. The fourth subject had a negative specific inhalation and skin test reaction to the latex extract. Peak expiratory flow monitoring at work and away from work showed a pattern consistent with work related asthma. These findings confirm that latex is a cause of occupational asthma in health care workers. PMID:8994533

  11. [Detection of pentachlorophenol in natural rubber latex].

    PubMed

    Jaworska, E

    1976-01-01

    The method of detection of pentachlorophenol in natural rubber latex is proposed. Pentachlorophenol is isolated from other nonrubber-like substances by thin-layer chromatography and identified by spectroscopic method in UV-light. Isolation of pentachlorophenol is carried out from water extracts obtained from the dry caoutchouc films, so the same method can be used for examination of the rubber articles designed for the medicinetoo.

  12. The role of water in latex coalescence

    SciTech Connect

    Sperry, P.R.; Snyder, B.S.

    1993-12-31

    The role of water in the particle deformation and compaction stage of latex polymer film formation is investigated via Minimum Film Formation Temperature (MFT) measurements as a function of polymer composition, time, and water content in the deposition and drying environments. Water content of the system ranged from very low (latex film predried well below the MFT before imposition of the temperature gradient, with low RH maintained throughout) to very high (wet latex cast on the gradient bar and high humidity during drying). A predried film exhibits a {open_quotes}dry{close_quotes} MFT transition, from opaque to clear film, only a few degrees above the {open_quotes}wet{close_quotes} MFT, indicating that so-called capillary forces associated with the presence of liquid water may be helpful but are not critical to film compaction. Indeed, with hydrophobic polymer compositions, the two MFT transitions converge with time. With hydrophilic compositions the {open_quotes}wet{close_quotes} MFT remains lower by several degrees, and this is ascribed to plasticization by water.

  13. [Latex gloves dermatitis in health care workers].

    PubMed

    Mattei, O; Di Martino, T; Ferraro, P

    2007-01-01

    With regard to health care workers the irritative contact dermatitis represents about the 80% of all the dermopathies in sanitary staff whereas the allergic contact dermatitis covers approximately the 20% of the professional dermatoses. In our study 4 cases of allergy to latex in hospital nurses are presented; the clinical history is described for each of them as well as the resulting judgment of suitability to the specific work. In general population the allergy to latex is estimated to be approximately 1-6%; in sanitary staff it rises to 5-12%. We have to observe that not all the sensitive subjects show symptoms of allergy. Actually the 4 cases described represent less than 1% of the surveyed group. The sensitization is likely to be so reduced also thanks to the application of preventive guide-lines such as the one proposed by NIOSH. In Italy the criteria in preventing allergic reactions to latex are illustrated in a consensus document issued by a study-team from Italian Association of the Health Workers.

  14. 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.

  15. Heterogeneity in styrene-butadiene latex films.

    PubMed

    Santos, Juliane P; Corpart, Pascale; Wong, Kenneth; Galembeck, Fernando

    2004-11-23

    Low-Tg styrene-butadiene (SB) latex films were investigated by noncontact atomic force microscopy and scanning electric potential microscopy, revealing a number of different morphologies and electric potential patterns across films cast from the same SB latex dispersions under the same conditions. Surface leveling and charge dispersion throughout the films are, thus, restrained even at temperatures above Tg and the minimum film-formation temperature. An unprecedented electric pattern is observed, in which the particle cores are more positive than the contacting particle outer layers. Different packing patterns, including cubic and hexagonal arrays, coexist in neighboring areas. Zonal centrifugation of the SB latex in sucrose density gradient shows that particles cover a broad range of densities. Thus, film surface heterogeneity is at least partly due to particle heterogeneity. Fractal dimensions of topographic profiles are lower than those of the electric potential profiles, showing that charge mobility is much more restrained than polymer chain motion at the film surface and that it imposes a limit to the charged chain-ends motion.

  16. Subconjunctival latex paint from occupational injury.

    PubMed

    Odhav, Ashika; Kollipara, Ramya; Teymoorian, Savak; Lord, Ron K; Lyon, David B

    2013-05-01

    Accidental eye trauma with spray guns are rare, but potentially very serious, injuries. Although it is agreed that these injuries require immediate and vigorous therapy, the specifics of such therapy are poorly defined. With latex paint sprayer injuries to hands and extremities, resulting chemical-induced inflammation, high-pressure necrosis, ischemic necrosis, and gangrene require surgical debridement and possibly, amputation. With eye injuries, treatment is directed at preservation of vision, as there is a potential risk of visual loss. There is currently no consensus on optimal treatment of ocular spray paint injuries. Here we propose a management approach to ocular spray paint injuries with a successful outcome in the case reported. We report the first case, to our knowledge, of an industrial airless spray gun injury that resulted in subconjunctival deposition of latex paint in a soft contact lens wearer. Vision was preserved with medical management consisting of irrigation and topical corticosteroids, antibiotics and cycloplegics. Although latex paint spray gun injuries to the eye are not encountered frequently in practice, this case shows that conservative medical management with no surgical intervention is effective for ocular injuries with preserved vision. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Production of latex agglutination reagents for pneumococcal serotyping

    PubMed Central

    2013-01-01

    Background The current ‘gold standard’ for serotyping pneumococci is the Quellung test. This technique is laborious and requires a certain level of training to correctly perform. Commercial pneumococcal latex agglutination serotyping reagents are available, but these are expensive. In-house production of latex agglutination reagents can be a cost-effective alternative to using commercially available reagents. This paper describes a method for the production and quality control (QC) of latex reagents, including problem solving recommendations, for pneumococcal serotyping. Results Here we describe a method for the production of latex agglutination reagents based on the passive adsorption of antibodies to latex particles. Sixty-five latex agglutination reagents were made using the PneuCarriage Project (PCP) method, of which 35 passed QC. The other 30 reagents failed QC due to auto-agglutination (n=2), no reactivity with target serotypes (n=8) or cross-reactivity with non-target serotypes (n=20). Dilution of antisera resulted in a further 27 reagents passing QC. The remaining three reagents passed QC when prepared without centrifugation and wash steps. Protein estimates indicated that latex reagents that failed QC when prepared using the PCP method passed when made with antiserum containing ≤ 500 μg/ml of protein. Sixty-one nasopharyngeal isolates were serotyped with our in-house latex agglutination reagents, with the results showing complete concordance with the Quellung reaction. Conclusions The method described here to produce latex agglutination reagents allows simple and efficient serotyping of pneumococci and may be applicable to latex agglutination reagents for typing or identification of other microorganisms. We recommend diluting antisera or removing centrifugation and wash steps for any latex reagents that fail QC. Our latex reagents are cost-effective, technically undemanding to prepare and remain stable for long periods of time, making them ideal for

  18. Production of latex agglutination reagents for pneumococcal serotyping.

    PubMed

    Ortika, Belinda D; Habib, Maha; Dunne, Eileen M; Porter, Barbara D; Satzke, Catherine

    2013-02-05

    The current 'gold standard' for serotyping pneumococci is the Quellung test. This technique is laborious and requires a certain level of training to correctly perform. Commercial pneumococcal latex agglutination serotyping reagents are available, but these are expensive. In-house production of latex agglutination reagents can be a cost-effective alternative to using commercially available reagents. This paper describes a method for the production and quality control (QC) of latex reagents, including problem solving recommendations, for pneumococcal serotyping. Here we describe a method for the production of latex agglutination reagents based on the passive adsorption of antibodies to latex particles. Sixty-five latex agglutination reagents were made using the PneuCarriage Project (PCP) method, of which 35 passed QC. The other 30 reagents failed QC due to auto-agglutination (n=2), no reactivity with target serotypes (n=8) or cross-reactivity with non-target serotypes (n=20). Dilution of antisera resulted in a further 27 reagents passing QC. The remaining three reagents passed QC when prepared without centrifugation and wash steps. Protein estimates indicated that latex reagents that failed QC when prepared using the PCP method passed when made with antiserum containing ≤ 500 μg/ml of protein. Sixty-one nasopharyngeal isolates were serotyped with our in-house latex agglutination reagents, with the results showing complete concordance with the Quellung reaction. The method described here to produce latex agglutination reagents allows simple and efficient serotyping of pneumococci and may be applicable to latex agglutination reagents for typing or identification of other microorganisms. We recommend diluting antisera or removing centrifugation and wash steps for any latex reagents that fail QC. Our latex reagents are cost-effective, technically undemanding to prepare and remain stable for long periods of time, making them ideal for use in low-income countries.

  19. 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.

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

    PubMed

    Bittner, C; Velasco Garrido, Marcial; Krach, L H; Harth, V

    2016-07-29

    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.

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

    PubMed

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

    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.

  2. 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.

  3. New constitutive latex osmotin-like proteins lacking antifungal activity.

    PubMed

    Freitas, Cleverson D T; Silva, Maria Z R; Bruno-Moreno, Frederico; Monteiro-Moreira, Ana C O; Moreira, Renato A; Ramos, Márcio V

    2015-11-01

    Proteins that share similar primary sequences to the protein originally described in salt-stressed tobacco cells have been named osmotins. So far, only two osmotin-like proteins were purified and characterized of latex fluids. Osmotin from Carica papaya latex is an inducible protein lacking antifungal activity, whereas the Calotropis procera latex osmotin is a constitutive antifungal protein. To get additional insights into this subject, we investigated osmotins in latex fluids of five species. Two potential osmotin-like proteins in Cryptostegia grandiflora and Plumeria rubra latex were detected by immunological cross-reactivity with polyclonal antibodies produced against the C. procera latex osmotin (CpOsm) by ELISA, Dot Blot and Western Blot assays. Osmotin-like proteins were not detected in the latex of Thevetia peruviana, Himatanthus drasticus and healthy Carica papaya fruits. Later, the two new osmotin-like proteins were purified through immunoaffinity chromatography with anti-CpOsm immobilized antibodies. Worth noting the chromatographic efficiency allowed for the purification of the osmotin-like protein belonging to H. drasticus latex, which was not detectable by immunoassays. The identification of the purified proteins was confirmed after MS/MS analyses of their tryptic digests. It is concluded that the constitutive osmotin-like proteins reported here share structural similarities to CpOsm. However, unlike CpOsm, they did not exhibit antifungal activity against Fusarium solani and Colletotrichum gloeosporioides. These results suggest that osmotins of different latex sources may be involved in distinct physiological or defensive events.

  4. ADSORPTION STUDIES IN A SYNTHETIC RUBBER LATEX-OVALBUMIN SYSTEM

    PubMed Central

    Williams, H. B.; Choppin, A. R.

    1950-01-01

    1. Adsorption of ovalbumin on the latex surface was in excess of the quantity required to produce coverage of the surface over most of the protein concentrations range which was investigated. 2. "S" shaped isothermals which probably indicated multilayer adsorption were obtained. 3. The quantity of ovalbumin required to produce a constant surface charge density on the latex particle surface was a function of the pH, and a theory of active centers on the latex particles has been suggested. 4. A shift in the isoelectric point from that of native ovalbumin has been observed for the protein when adsorbed on a synthetic latex. PMID:14824490

  5. 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

  6. Extraction of high-quality genomic DNA from latex-containing plants.

    PubMed

    Michiels, An; Van den Ende, Wim; Tucker, Mark; Van Riet, Liesbet; Van Laere, André

    2003-04-01

    The isolation of intact, high-molecular-mass genomic DNA is essential for many molecular biology applications including long PCR, endonuclease restriction digestion, Southern blot analysis, and genomic library construction. Many protocols are available for the extraction of DNA from plant material. However, for latex-containing Asteraceae (Cichorioideae) species, standard protocols and commercially available kits do not produce efficient yields of high-quality amplifiable DNA. A cetyltrimethylammonium bromide protocol has been optimized for isolation of genomic DNA from latex-containing plants. Key steps in the modified protocol are the use of etiolated leaf tissue for extraction and an overnight 25 degrees C isopropanol precipitation step. The purified DNA has excellent spectral qualities, is efficiently digested by restriction endonucleases, and is suitable for long-fragment PCR amplification.

  7. [Latex allergy in a paediatric hospital. Characteristics and risk factors].

    PubMed

    Bailey, Michael; Norambuena, Ximena; Roizen, Gigia; Rodríguez, Jorge; Quezada, Arnoldo

    The prevalence of latex sensitisation varies according to the population studied. There are various risk factors that increase latex sensitisation, such as genetic risk, atopy, and multiple surgeries. To characterise patients referred to an Immunology Unit with suspected latex allergy, and to analyse their clinical features and risk factors. A retrospective, descriptive study was conducted on children suspected of latex allergy. Their medical records were reviewed in order to assess symptoms with contact or exposure to latex materials. Known risk factors to latex sensitisation, such as pathologies requiring repeated surgery (spina bifida, myelomeningocele, scoliosis and nephro-urological alterations), atopy (rhinitis, asthma, atopic dermatitis) were investigated. A prick test and/or specific IgE to latex were also performed. A multivariate logistic regression model was performed to find associations between symptoms triggered by exposure to latex with underlying diseases and other risk conditions. A total of 106 patients were enrolled in the study, of whom 50 were evaluable. At diagnosis 96% of patients were older than five years. Most of the risk factors described were observable in these patients, such as multiple surgeries, neurological and nephro-urological malformations, surgery before one year-old, and repeated bladder catheterisation. After latex exposure, mucous cutaneous manifestations were the most common (52%), followed by respiratory symptoms (36%). All patients were sensitised and allergic to latex. Latex allergy is a significant problem in children with risk factors. The results shown in this study raise important challenges for preventive measures and awareness. Copyright © 2016 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Polymer concrete patching manual

    NASA Astrophysics Data System (ADS)

    Fontana, J. J.; Bartholomew, J.

    1982-06-01

    The practicality of using polymer concrete to repair deteriorated portland cement concrete bridge decks and pavements was demonstrated. This manual outlines the procedures for using polymer concrete as a rapid patching material to repair deteriorated concrete. The process technology, materials, equipment, and safety provisions used in manufacturing and placing polymer concrete are discussed. Potential users are informed of the various steps necessary to insure successful field applications of the material.

  9. Latex Surface and Bulk Coagulation Induced by Solvent Vapors.

    PubMed

    Braga; da Silva Md; Cardoso; Galembeck

    2000-08-01

    Latex exposure to solvent vapors leads to highly specific changes in latex stability as well as on the morphologies of the particle association products, depending on the latex and solvent used. Examples of solvent vapor-induced aggregation are given: surface films are obtained on two PS latexes; in one case, the film surface is mirror-reflective and very flat, as evidenced by AFM. Another PS latex coagulates under exposure to acetone vapors, and the morphologies of the coagula are highly sensitive to the exposure conditions. This latex yields a highly porous foam-like structure, in which particles are strongly coalesced but form percolating patches around the pores. The same latex but under other conditions produces a coagulum of large numbers of aggregated particles with a raspberry-like morphology. Density centrifugation experiments show that the effect of solvents on different latex fractions is not uniform, and some fractions show larger density changes than others, thus evidencing a variability in their swelling ability. Copyright 2000 Academic Press.

  10. Polymer latex particles: Preparation, characterization, and coating patterns

    SciTech Connect

    Wang, Leeyih.

    1993-01-01

    The coating patterns of polystyrene latex after spin drying have been intensively investigated. The model microsphere was prepared using emulsifier-free emulsion polymerization. The resulting polystyrene latex was 0.54 [mu]m in diameter with the polydispersity of 1.02. The mobility of latex spheres in concentrated dispersions was studied by diffusing wave spectroscopy (DWS). The diffusion coefficient of the polystyrene spheres dispersed in water decreased as the concentration of latex particles increased. The concentration dependence of the diffusion coefficient of this latex determined by DWS matched closely to the short-time diffusion of poly(methyl methacrylate) latex in a mixed organic fluid determined by PCS using the refractive index matching method. It indicates that the electrical repulsive force between particles in this system has a small effect on the short-time mobility of particles. This result was also confirmed by the diffusion coefficients of polystyrene spheres dispersed in water with the addition of sodium chloride, or dispersed in NMF. The presence of surfactants, SDS and C12E5, in the dispersed medium led to a great reduction on the diffusivity of latex spheres. A two dimensional ordered array of particles can be obtained from the spin drying of polystyrene latex by adding surfactants in a suitable concentration range or by choosing an appropriate substrate and/or dispersing fluid. A mechanism for the formation of hexagonally packed particles was proposed as the actions of three factors: retractive, frictional, and capillary forces.

  11. Home Healthcare Workers: How to Prevent Latex Allergies

    MedlinePlus

    ... polymer gloves appropriate for infectious materials. • Provide reduced-protein, powder-free gloves, if latex gloves are selected for ... offer protection against infectious materials. • Ask for reduced-protein, powder-free gloves, if your employer supplies latex gloves. • ...

  12. Natural rubber latex allergy and dental practice.

    PubMed

    Desai, Shalin V

    2007-12-01

    Natural rubber latex (NRL) allergy is a significant clinical problem with potentially life-threatening complications. Oral health care professionals must be able to screen for NRL allergy and refer patients or staff to a specialist for definitive diagnosis. Protocol for its management must be developed and incorporated into daily practice. Practitioners must be able to recognize and treat NRL exposure emergencies. Knowledge of the availability of substitute products and an adequate fresh stock of such products in dental practice can minimise the risk of adverse NRL sensitivity.

  13. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    NASA Astrophysics Data System (ADS)

    Hassmoro, N. F.; Rusop, M.; Abdullah, S.

    2013-06-01

    The differential microemulsion polymerization was used to synthesize latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinker respectively 1-5 weight% of monomer total. Butyl acrylate (BA), butyl methacrylate (BMA), and methacrylic acid (MAA) was used as the monomer. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinker added in the polymerization was optimized and we found that the particle sizes fall in the range of 30-60 nm. The structural morphology of the uncrosslinked latex represented the most homogeneous image compared to the crosslinked latex. The effect of the amount of crosslinker on the particle sizes investigated by the Zeta-sizer Nano series while Atomic Force microscopy (AFM) was used to study the structural properties of latex nanoparticles.

  14. 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

  15. [Latex and synthetic polymers gloves: protective effectiveness against biological risk].

    PubMed

    Balbiani, Lara; Sossai, D

    2008-01-01

    The quick evolution of knowledge about latex and, especially, its effectiveness as protection against biological risks on one hand, and, on the other hand, as trigger of cutaneous, respiratory and sistemic allergic diseases, required a marked distinction between conditions in which latex is necessary and conditions in which latex could be substituted by syntetic polymers. The aim of this study is to verify protective effectiveness of gloves made of syntetic polymers against biological risks compared with latex gloves which until now have been considered as the best protection. Literature review. The most recent studies seem to consider neoprene gloves as the safest protection to replace latex in working activities with high biological risk exposure. The literature review marked the lack of studies exclusively focused on glove permeability towards biological agents. It seems therefore necessary to investigate this topic to validate results and to guarantee a suitable protection to workers daily exposed to biological risk.

  16. Prediction of Flexural Strength of Concretes Containing Silica Fume and Styrene-Butadiene Rubber (SBR) with an Empirical Model

    NASA Astrophysics Data System (ADS)

    Shafieyzadeh, M.

    2015-12-01

    In the flexural test, the theoretical maximum tensile stress at the bottom fiber of a test beam is known as the modulus of rupture or flexural strength. This work deals with the effects of Silica Fume and Styrene-Butadiene Latex (SBR) on flexural strength of concrete. An extensive experimentation was carried out to determine the effects of silica fume and SBR on flexural strength of concrete. Two water-binder ratios and several percentages of silica fume and SBR were considered. Abrams' Law, which was originally formulated for conventional concrete containing cement as the only cementations material, is used for prediction of flexural strength of these concretes. The aim of this work is to construct an empirical model to predict the flexural strength of silica fume-SBR concretes using concrete ingredients and time of curing in water. Also, the obtained results for flexural strength tests have been compared with predicted results.

  17. Latex allergy: a follow up study of 1040 healthcare workers

    PubMed Central

    Filon, F Larese; Radman, G

    2006-01-01

    Background Natural rubber latex allergy can cause skin and respiratory symptoms The aim of this study was to evaluate the prevalence and incidence of latex related symptoms and sensitisation among a large group of healthcare workers in Trieste hospitals, followed for three years before and after the introduction of powder‐free gloves with low latex release. Methods In the years 1997–99 the authors evaluated 1040 healthcare workers exposed to latex allergen for latex related symptoms and sensitisation by means of a questionnaire, a medical examination, skin prick tests, and IgE specific antibody assay. The second evaluation was carried out in the years 2000–02, subsequent to the changeover to a powder‐free environment. Results Glove related symptoms were seen in 21.8% of the nurses (227), mostly consisting of mild dermatitis: 38 (3.6%) complaining of contact urticaria and 24 (2.3%) of asthma and/or rhinitis. These symptoms were significantly related to skin prick tests positive to latex (OR = 9.70; 95% CI 5.5 to 17) and to personal atopy (OR = 2.29; 95% CI 1.6 to 3.2). Follow up was completed in 960 subjects (92.3%): 19 new subjects (2.4%) complained of itching erythema when using gloves, but none was prick positive to latex. Symptoms significantly improved and in most cases disappeared (p<0.0001). Conclusions Simple measures such as the avoidance of unnecessary glove use, the use of non‐powdered latex gloves by all workers, and use of non‐latex gloves by sensitised subjects can stop the progression of latex symptoms and can avoid new cases of sensitisation. PMID:16421390

  18. Human fibrinogen monolayers on latex particles: role of ionic strength.

    PubMed

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

    2013-03-19

    The adsorption of human serum fibrinogen on polystyrene latex particles was studied using the microelectrophoretic and concentration depletion methods. Measurements were carried out for pH 3.5 and an ionic strength range of 10(-3) to 0.15 M NaCl. The electrophoretic mobility of latex was determined as a function of the amount of adsorbed fibrinogen (surface concentration). A monotonic increase in the electrophoretic mobility (zeta potential) of the latex was observed, indicating a significant adsorption of fibrinogen on latex for all ionic strengths. No changes in the latex mobility were observed for prolonged time periods, suggesting the irreversibility of fibrinogen adsorption. The maximum coverage of fibrinogen on latex particles was precisely determined using the depletion method. The residual protein concentration after making contact with latex particles was determined by electrokinetic measurements and AFM imaging where the surface coverage of fibrinogen on mica was quantitatively determined. The maximum fibrinogen coverage increased monotonically with ionic strength from 1.8 mg m(-2) for 10(-3) M NaCl to 3.6 mg m(-2) for 0.15 M NaCl. The increase in the maximum coverage was interpreted in terms of the reduced electrostatic repulsion among adsorbed fibrinogen molecules. The experimental data agree with theoretical simulations made by assuming a 3D unoriented adsorption of fibrinogen. The stability of fibrinogen monolayers on latex was also determined in ionic strength cycling experiments. It was revealed that cyclic variations in NaCl concentration between 10(-3) and 0.15 M induced no changes in the latex electrophoretic mobility, suggesting that there were no irreversible molecule orientation changes in the monolayers. On the basis of these experimental data, a robust procedure of preparing fibrinogen monolayers on latex particles of well-controlled coverage was proposed.

  19. 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.

  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. 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.

  2. 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.

  3. A randomised trial of the durability of non-allergenic latex-free surgical gloves versus latex gloves.

    PubMed Central

    Newsom, S. W.; Smith, M. O.; Shaw, P.

    1998-01-01

    A prospective randomised trial was performed to compare the robustness of a new non-latex surgical glove with a standard latex glove when worn by four general surgeons in a district general hospital. Gloves were retrieved after surgery and examined using the European Standard Test for punctures. The overall puncture rate was 10.1%, and there was no significant difference in the rates between the two types of glove, although punctures in the non-latex glove tended to be larger and more readily noted by the wearer. The increase in latex allergy among health care staff dictates the need for gloves made from other materials, which may also be useful for operations on latex-allergic patients. PMID:9771234

  4. Coalescence of polymeric particles in latex films

    SciTech Connect

    Cabane, B.

    1996-01-01

    Common coatings such as paints or adhesives can be made from aqueous dispersions which are evaporated on the substrate to give a continuous film. The most widely studied systems are latex dispersions, which contain submicrometric particles of soft organic polymers dispersed in water. With such systems, the difficulty is to ensure that the resulting film will be resistant to water, despite the fact that it has been prepared as a stable aqueous dispersion. For this purpose the dispersion must pass through some irreversible transformations. A radical transformation is the coalescence of particles, which yields a continuous polymer film. This transformation will be described for surfactant-covered latex particles, which coalesce in the wet state, and for polyelectrolyte-covered particles, which coalesce in the dry state. The consequences of coalescence will be examined, in particular the expulsion of the surfactants towards the outer boundaries of the film. This may be detrimental to the adhesive properties of the film: thus alternative routes for maintaining resistance to water without using coalescence of the particles will also be examined. {copyright} {ital 1996 American Institute of Physics.}

  5. 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.

  6. In vitro neuronal cytotoxicity of latex and nonlatex orthodontic elastics.

    PubMed

    Hanson, Mark; Lobner, Doug

    2004-07-01

    Although the toxicity of many dental materials has been thoroughly investigated, the toxicity of orthodontic elastic materials has not been extensively tested. We evaluated the neurotoxicity of 3 latex and 3 nonlatex orthodontic elastics in murine cerebral cortical cell cultures. Standard-sized pieces of each material from 3 manufacturers (American, Masel, and GAC) were placed on culture well inserts, allowing the material to be exposed to the culture bathing media without causing physical disruption of the cells. Cell death was quantified by assaying the release of the cytosolic enzyme lactate dehydrogenase. Exposure of cortical cultures to the nonlatex elastics did not cause significant neuronal death, but exposure to each of the latex elastics resulted in significant neuronal death. The neuronal death induced by each of the latex elastics was blocked by adding the metal chelator, EDTA (calcium disodium ethylenediaminetetraacetate). Because many latexes use zinc-containing compounds in the prevulcanization process, and the death induced had characteristics similar to zinc-induced neuronal death, it seems likely that the toxicity of latex elastics was mediated by zinc release. Because ingestion of zinc is not a health risk, the results suggest that, in spite of the finding that latex elastics have higher in vitro cytotoxicity than nonlatex elastics, the use of latex elastics in orthodontics is acceptable.

  7. Sublingual desensitization: a new approach to latex allergy problem.

    PubMed

    Patriarca, Giampiero; Nucera, Eleonora; Pollastrini, Emanuela; Roncallo, Chiara; Buonomo, Alessandro; Bartolozzi, Francesco; De Pasquale, Tiziana; Gasbarrini, Giovanni; Schiavino, Domenico

    2002-10-01

    The prevalence of latex allergy has rapidly increased. Clinical manifestations range from contact urticaria-angioedema and rhinoconjunctivitis to more severe bronchial asthma and anaphylactic shock. The only effective therapy is desensitization. We studied 24 patients allergic to latex: 12 of them underwent a rush (4-day) sublingual desensitization to latex, performed by putting increasing doses of latex extract under the patients' tongues for 3 min every 20 min, followed by a maintenance therapy. The other 12 patients were considered controls. The sublingual rush desensitization protocol was successfully completed in all patients with no side effects. After 3 mo, all patients underwent an allergological evaluation, which showed a significant improvement of symptoms scores after challenges in the treated group as compared with the controls. All the desensitized patients can now wear latex gloves and undergo medical procedures without any symptoms. We present 12 cases of latex allergy in patients who underwent desensitization by a sublingual exposure protocol. This study provides evidence that a safe therapeutic approach to latex allergy is possible.

  8. 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.

  9. 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.

  10. Lunar concrete for construction

    SciTech Connect

    Cullingford, H.S.; Keller, M.D.

    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. 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 data base. 10 refs., 3 figs., 2 tabs.

  11. 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.

  12. Properties of Sulfur Concrete.

    DTIC Science & Technology

    1979-07-06

    This report summarizes the state of the art of sulfur concrete . Sulfur concrete is created by mixing molten sulfur with aggregate and allowing the...and many organic compounds. It works well as a rapid runway repair material. Sulfur concrete also has unfavorable properties. It has poor durability

  13. [Successful desensitization to latex by sublingual immunotherapy in a health worker].

    PubMed

    Bueno-De Sá, Adriano; Gaspar, Angela; Solé, Dirceu; Morais-Almeida, Mário

    2014-01-01

    Latex allergy is still a public health problem responsible for some occupational diseases tough to be treated without removing the patient from his/her workspace. For patients allergic to latex, sublingual immunotherapy (SLIT) for latex is a tool that can be very useful. We report the case of a nurse with latex allergy who underwent successful desensitization to latex by SLIT, and discuss about possible causes of the success of this therapy.

  14. Radiation dose required for the vulcanization of natural rubber latex

    NASA Astrophysics Data System (ADS)

    Haque, M. E.; Dafader, N. C.; Akhtar, F.; Ahmad, M. U.

    1996-10-01

    The radiation dose required for the vulcanization of natural rubber latex was optimized. To enhance the crosslinking, several sensitizers were used. Among the sensitizers, n-butyl acrylate ( n-BA) alone was found to be the best one. The effects of concentration of n-Ba, mixing and standing time of latex with n-BA on the tensile properties of latex film were investigated. 12 kGy radiation dose, 5 phr n-BA and 30-40 min of mixing time were found to be the optimum conditions for irradiation.

  15. Comparative Study on Plant Latex Particles and Latex Coagulation in Ficus benjamina, Campanula glomerata and Three Euphorbia species

    PubMed Central

    Bauer, Georg; Gorb, Stanislav N.; Klein, Marie-Christin; Nellesen, Anke; von Tapavicza, Max; Speck, Thomas

    2014-01-01

    Among latex-producing plants, mainly the latex of Hevea brasiliensis has been studied in detail so far, while comprehensive comparative studies of latex coagulation mechanisms among the more than 20,000 latex-bearing plant species are lacking. In order to give new insights into the potential variety of coagulation mechanisms, the untreated natural latices of five latex-bearing plants from the families Euphorbiaceae, Moraceae and Campanulaceae were visualised using Cryo-SEM and their particle size compared using the laser diffraction method. Additionally, the laticifers of these plants species were examined in planta via Cryo-SEM. Similar latex particle sizes and shape were found in Ficus benjamina and Hevea brasiliensis. Hence, and due to other similarities, we hypothesize comparable, mainly chemical, coagulation mechanisms in these two species, whereas a physical coagulation mechanism is proposed for the latex of Euphorbia spp. The latter mechanism is based on the huge amount of densely packed particles that after evaporation of water build a large surface area, which accelerates the coagulation procedure. PMID:25409036

  16. Comparative study on plant latex particles and latex coagulation in Ficus benjamina, Campanula glomerata and three Euphorbia species.

    PubMed

    Bauer, Georg; Gorb, Stanislav N; Klein, Marie-Christin; Nellesen, Anke; von Tapavicza, Max; Speck, Thomas

    2014-01-01

    Among latex-producing plants, mainly the latex of Hevea brasiliensis has been studied in detail so far, while comprehensive comparative studies of latex coagulation mechanisms among the more than 20,000 latex-bearing plant species are lacking. In order to give new insights into the potential variety of coagulation mechanisms, the untreated natural latices of five latex-bearing plants from the families Euphorbiaceae, Moraceae and Campanulaceae were visualised using Cryo-SEM and their particle size compared using the laser diffraction method. Additionally, the laticifers of these plants species were examined in planta via Cryo-SEM. Similar latex particle sizes and shape were found in Ficus benjamina and Hevea brasiliensis. Hence, and due to other similarities, we hypothesize comparable, mainly chemical, coagulation mechanisms in these two species, whereas a physical coagulation mechanism is proposed for the latex of Euphorbia spp. The latter mechanism is based on the huge amount of densely packed particles that after evaporation of water build a large surface area, which accelerates the coagulation procedure.

  17. Current prevalence rate of latex allergy: Why it remains a problem?

    PubMed Central

    Wu, Miaozong; McIntosh, James; Liu, Jian

    2016-01-01

    Objectives: This article aims to review the current prevalence rate of latex allergy among healthcare workers, susceptible patients, and the general public, and to investigate why latex is still a ubiquitous occupational health hazard. Methods: Scientific publications on PubMed, particularly those published within the last five years, and current regulations from agencies such as Food and Drug Administration (FDA) were reviewed. Consumer and commercial products that may contain latex were also surveyed. Results: Approximately 12 million tons of natural rubber latex is produced annually and is widely used to manufacture millions of consumer and commercial products. Only limited number of latex-derived products have been approved and regulated by government agencies, such as FDA, whereas the majority of finished products do not label whether they contain latex. Owing to millions of unidentifiable products containing latex and many routes for exposure to latex, preventing contact with latex allergens and reducing the prevalence of latex allergy are more difficult than expected. Reported data suggest that the average prevalence of latex allergy worldwide remains 9.7%, 7.2%, and 4.3% among healthcare workers, susceptible patients, and general population, respectively. Conclusions: Latex-derived products are ubiquitous, and latex allergy remains a highly prevalent health risk in many occupations and to the general population. Developing alternative materials and increasing the ability to identify and label latex-derived products will be practicable approaches to effectively control the health risks associated with latex. PMID:27010091

  18. Current prevalence rate of latex allergy: Why it remains a problem?

    PubMed

    Wu, Miaozong; McIntosh, James; Liu, Jian

    2016-05-25

    This article aims to review the current prevalence rate of latex allergy among healthcare workers, susceptible patients, and the general public, and to investigate why latex is still a ubiquitous occupational health hazard. Scientific publications on PubMed, particularly those published within the last five years, and current regulations from agencies such as Food and Drug Administration (FDA) were reviewed. Consumer and commercial products that may contain latex were also surveyed. Approximately 12 million tons of natural rubber latex is produced annually and is widely used to manufacture millions of consumer and commercial products. Only limited number of latex-derived products have been approved and regulated by government agencies, such as FDA, whereas the majority of finished products do not label whether they contain latex. Owing to millions of unidentifiable products containing latex and many routes for exposure to latex, preventing contact with latex allergens and reducing the prevalence of latex allergy are more difficult than expected. Reported data suggest that the average prevalence of latex allergy worldwide remains 9.7%, 7.2%, and 4.3% among healthcare workers, susceptible patients, and general population, respectively. Latex-derived products are ubiquitous, and latex allergy remains a highly prevalent health risk in many occupations and to the general population. Developing alternative materials and increasing the ability to identify and label latex-derived products will be practicable approaches to effectively control the health risks associated with latex.

  19. 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?

  20. Cementing multilateral wells with latex cement

    SciTech Connect

    1997-08-01

    A multilateral well is a well with one or more branches or lateral sections extending from its main wellbore. The laterals can be openhole or cased hole. When laterals are cased hole, the cement integrity for casing support and zonal isolation is very important. When cementing the lateral sections of multilateral wells, it is important to use a cement with high strength and durability to support the liner throughout the life of the well and to support the lateral section. The cement column is subjected to various stresses when the cemented inner stub is cut. High tensile strength, flexural strength, and crack resistance are required. These properties are necessary to make a clean cut through the cement sheath that does not induce cracks in the cement column. Latex cement is commonly used for its gas-migration-control property.

  1. Thermoresponsive latexes for fragrance encapsulation and release.

    PubMed

    Popadyuk, N; Popadyuk, A; Kohut, A; Voronov, A

    2016-04-01

    To synthesize cross-linked latex particles protecting the encapsulated fragrance at ambient temperatures and facilitating the release of cargo at the temperature of the surface of the skin that varies in different regions of the body between 33.5 and 36.9°C. Poly(stearyl acrylate) (PSA), a polymer with long crystallizable alkyl side chains (undergoes order-disorder transitions at 45°C), was chosen as the main component of the polymer particles. As a result, new thermoresponsive polymer particles for fragrance encapsulation were synthesized and characterized, including assessing the performance of particles in triggered release by elevated temperature. To obtain network domains of various crystallinity, stearyl acrylate was copolymerized with dipropylene glycol acrylate caprylate (DGAC) (comonomer) in the presence of a dipropylene glycol diacrylate sebacate (cross-linker) using the miniemulsion process. Comonomers and a cross-linker were mixed directly in a fragrance during polymerization. Fragrance release was evaluated at 25, 31, 35 and 39°C to demonstrate a new material potential in personal/health care skin-related applications. Particles protect the fragrance from evaporation at 25°C. The fragrance release rate gradually increases at 31, 35 and 39°C. Two slopes were found on release plots. The first slope corresponds to a rapid fragrance release. The second slope indicates a subsequent reduction in the release rate. Crystalline-to-amorphous transition of PSA triggers the release of fragrances from cross-linked latex particles at elevated temperatures. The presence of the encapsulated fragrance, as well as the inclusion of amorphous fragments in the polymer network, reduces the particle crystallinity and enhances the release. Release profiles can be tuned by temperature and controlled by the amount of loaded fragrance and the ratio of comonomers in the feed mixture. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  2. Concreteness Effects and Syntactic Modification in Written Composition.

    ERIC Educational Resources Information Center

    Sadoski, Mark; Goetz, Ernest T.

    1998-01-01

    Investigates whether concreteness was related to a key characteristic of written composition--the cumulative sentence with a final modifier--which has been consistently associated with higher quality writing. Supports the conceptual-peg hypothesis of dual coding theory, with concrete verbs providing the pegs on which cumulative sentences are…

  3. Structure formation control of foam concrete

    NASA Astrophysics Data System (ADS)

    Steshenko, Aleksei; Kudyakov, Aleksander; Konusheva, Viktoriya; Syrkin, Oleg

    2017-01-01

    The process of predetermined foam concrete structure formation is considered to be a crucial issue from the point of process control and it is currently understudied thus defining the need for additional research. One of the effective ways of structure formation control in naturally hardening foam concrete is reinforcement with dispersed fibers or introduction of plasticizers. The paper aims at studying the patterns of influence of microreinforcing and plasticizing additives on the structure and performance properties of foam concrete. Preparation of foam concrete mix has been conducted using one-step technology. The structure of modified foam concrete has been studied by means of electron microscopy. The cellular structure of foam concrete samples with the additives is homogeneous; the pores are uniformly distributed over the total volume. It has been revealed that introduction of the Neolas 5.2 plasticizer and microreinforcing fibers in the foam concrete mixture in the amount of 0.4 - 0.1 % by weight of cement leads to reduction of the average pore diameter in the range of 45.3 to 30.2 microns and the standard deviation of the pore average diameter from 23.6 to 9.2 in comparison with the sample without additive. Introduction of modifying additives has stimulated formation of a large number of closed pores. Thus porosity of conditionally closed pores has increased from 16.06 % to 34.48 %, which has lead to increase of frost resistance brand of foam concrete from F15 to F50 and to reduction of its water absorption by weight by 20 %.

  4. Prevalence of type I allergy to natural rubber latex and type IV allergy to latex and rubber additives in operating room staff with glove-related symptoms.

    PubMed

    Miri, Sara; Pourpak, Zahra; Zarinara, Alireza; Zarinara, Alam; Heidarzade, Marzieh; Kazemnejad, Anoushirvan; Kardar, Gholamali; Firooz, Alireza; Moin, Athar

    2007-01-01

    There is lack of data on the prevalence of latex allergy in the health care setting in Iran. This study was performed to determine the prevalence of type I latex allergy and type IV allergy to latex and rubber additives among the operating room staff with glove-related symptoms in 13 general hospitals in Tehran. Skin-prick tests with commercial latex extract, patch tests with latex and 25 rubber additive series, and total and latex-specific IgE detection were performed on the operating room staff who reported latex glove-related symptoms. Five hundred twelve self-administered questionnaires (100%) were completed by all operating room staff and latex glove-related symptoms were reported by 59 (11.5%) employees. Among all symptomatic operating room staff tested, the prevalence of type I latex allergy was 30.5% and the prevalence rates of type IV allergy to latex and rubber additives were 16.7 and 14.6%, respectively. The most positive patch test result with rubber additives was related to tetramethylthiuram monosulfide (38.5%). The risk factors for type I latex allergy were female sex (p = 0.009) and positive patch test with rubber additives (p = 0.012). Subjects who had positive patch test with latex were significantly more likely to have positive patch test with rubber additives (p < 0.0001). Our results showed a high prevalence of type I latex allergy and type IV allergy to latex and rubber additives. Based on this study, we recommend eliminating powdered latex gloves from the operating rooms of the 13 studied general hospitals and support the substitution of powder-free latex gloves.

  5. 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

  6. [Allergic reactions caused by latex: warning to health workers].

    PubMed

    Lopes, R A; Lopes, M H

    1999-01-01

    In this study, a bibliographic survey is made of all articles, published during the last few years, dealing with allergic reactions to latex. The first article on allergic reactions associated with latex was published in Britain, in 1979. Since then, the number of cases reported have increased (Barton, 1993). Type I allergic reaction (immediate reaction) and Type IV (delayed reaction) are part of the latex allergic process (Steelman, 1995). Contact allergy is due to inadequate washing during manufacture, which results in the retention of water-soluble proteins that cause allergic reactions in susceptible people. A wide variety of allergic reactions that vary from contact dermatitis to anaphylatic shock are described in literature. These finding show that a health team must know the probable implications of latex allergy.

  7. The manufacture of gloves from natural rubber latex.

    PubMed

    Yip, Esah; Cacioli, Paul

    2002-08-01

    Gloves that will provide a barrier of protection from infectious organisms are an essential feature of medical practice for the protection of both patients and medical personnel. Natural rubber latex has consistently been the most satisfactory raw material for the manufacture of gloves. Certain latex proteins, carried over into the finished product by inadequate manufacturing processes, may pose a risk of provoking allergic reactions in some patients and medical workers. As with any allergy, the risk depends on the route of exposure and dose. Hence, the method of manufacture, including the means used to coat gloves to make donning easy, can influence the eventual exposure of sensitive people to latex allergens. In this article, we describe the several processes in use and their effects on latex protein content.

  8. Safety of latex urinary catheters for the short time drainage

    PubMed Central

    Hosseinpour, Mehrdad; Noori, Saeed; Amir-Beigi, Mahdieh; Pourfakharan, Mohammad Hassan; Ehteram, Hassan; Hamsayeh, Mohadese

    2014-01-01

    Background: In this study, we attempt to identify the most appropriate catheter (silicone vs. latex) for short-term urinary catheterization. We compared the post-operative clinico-pathological complications between latex and silicone for short term catheterization in rabbits with hypospadias. Materials and Methods: Forty rabbits were used in our study to compare complications of catheterization. They were divided in two groups. Hypospadias like defect was created by a 1 cm long excision of the ventral urethra. For urethroplasty, we used tubularized incised plate technique. Latex and silicon catheters were used in groups 1 and 2, respectively. Post-operatively, routine laboratory urine test and complications (allergy, infection, bleeding) were compared in groups. Results: A total of 40 rabbits underwent hypospadias repair. Findings showed that there were no significant differences between groups based on urine test indices (P = NS). Urinary tract infection rate was 10% (2 rabbits) in latex and 0% in silicone groups (P = NS). There were no significant differences between groups regarding of cystitis grades between study groups (P = NS). Conclusion: It seems that urinary tract catheterization with latex catheters is a safe, feasible, and in-expensive procedure for short-term post-operative course in hypospadias surgery in patients without latex hypersensitivity. PMID:25125890

  9. Proteomics analysis of latex from Hevea brasiliensis (clone RRIM 600).

    PubMed

    Habib, Mohd Afiq Hazlami; Yuen, Gan Chee; Othman, Fazilah; Zainudin, Nurul Nabilah; Latiff, Aishah Abdul; Ismail, Mohd Nazri

    2017-04-01

    The natural rubber latex extracted from the bark of Hevea brasiliensis plays various important roles in today's modern society. Following ultracentrifugation, the latex can be separated into 3 layers: C-serum, lutoids, and rubber particles. Previous studies have shown that a large number of proteins are present in these 3 layers. However, a complete proteome for this important plant is still unavailable. Protein sequences have been recently translated from the completed draft genome database of H. brasiliensis, leading to the creation of annotated protein databases of the following H. brasiliensis biosynthetic pathways: photosynthesis, latex allergens, rubberwood formation, latex biosynthesis, and disease resistance. This research was conducted to identify the proteins contained within the latex by way of de novo sequencing from mass spectral data obtained from the 3 layers of the latex. Peptides from these proteins were fragmented using collision-induced dissociation, higher-energy collisional dissociation, and electron-transfer dissociation activation methods. A large percentage of proteins from the biosynthetic pathways (63% to 100%) were successfully identified. In addition, a total of 1839 unique proteins were identified from the whole translated draft genome database (AnnHBM).

  10. The durability of silicone versus latex mock arteries.

    PubMed

    Conti, J C; Strope, E R; Goldenberg, L M; Price, K S

    2001-01-01

    Latex mock arteries used in medical device testing allow researchers to evaluate mechanical characteristics of intravascular medical products without using animal or human clinical studies for this data. Such intravascular situations include determining properties such as drag and steerability of catheters, recoil of vascular stents, and clinician training. In fatigue testing, the latex mock arteries are used to receive deployed products and are then repeatedly pressurized at biologically relevant pressures to determine the long term durability of the product. By matching dimensions and pressure-volume relationships (compliance) of these latex tubes, researchers have a reliable means to evaluate and predict product lifetimes. The problem with latex mock arteries is two-fold: First, they are opaque so the product inside the artery cannot be seen during evaluation of the integrity of the product or during clinical training sessions. Second, latex tubes fatigue; therefore, the loading that they place on the internalized products varies with time. During long term durability studies, latex tubes may have to be replaced as often as every 100 million cycles. This can be problematic with products that are difficult to redeploy. We have developed a clear silicone mock artery system that allows us to fabricate three-dimensional objects, including tubes with precise geometric and mechanical properties. Our evaluations show that the mock arteries can be stressed up to 400 million cycles with little or no change in mechanical properties. We are in the process of continuing evaluations to determine long term durability.

  11. [Latex proteins as the trigger of respiratory and systemic allergies].

    PubMed

    Baur, X; Jäger, D; Engelke, T; Rennert, S; Czuppon, A B

    1992-08-21

    56 patients (52 members of the hospital's staff, four with other employment) who had hypersensitivity reactions to latex articles and developed an immediate-type response to latex extract with the skin-prick test were studied. Specific IgE antibodies were present in the enzyme-allergo-sorbent test of 50 of the subjects. Latex-containing surgical and household gloves were the main cause of allergies. Patients with isolated contact urticaria (n = 8) had a tendency towards lower antibody concentrations than those with additional respiratory and/or systemic symptoms (n = 48). Occupation-related provocation tests triggered rhinitis in 19, conjunctivitis in ten, and bronchial obstruction in six. The main allergen was found to be a protein with a relative molecular mass of 58,000, originating from the latex milk and passing from the latex glove into the glove powder. In the course of usual activities considerable allergen inhalation can occur. Even small amounts (e.g. 400 ng/ml) can precipitate significant allergic reactions. The results show that the main latex allergen, a glycine-rich protein molecule, can cause cutaneous, inhalant and systemic hypersensitivity reactions.

  12. Euphorbia plant latex is inhabited by diverse microbial communities.

    PubMed

    Gunawardana, Manjula; Hyde, Embriette R; Lahmeyer, Sean; Dorsey, Brian L; La Val, Taylor P; Mullen, Madeline; Yoo, Jennifer; Knight, Rob; Baum, Marc M

    2015-12-01

    The antimicrobial properties and toxicity of Euphorbia plant latex should make it a hostile environment to microbes. However, when specimens from Euphorbia spp. were propagated in tissue culture, microbial growth was observed routinely, raising the question whether the latex of this diverse plant genus can be a niche for polymicrobial communities. Latex from a phylogenetically diverse set of Euphorbia species was collected and genomic microbial DNA extracted. Deep sequencing of bar-coded amplicons from taxonomically informative gene fragments was used to measure bacterial and fungal species richness, evenness, and composition. Euphorbia latex was found to contain unexpectedly complex bacterial (mean: 44.0 species per sample; 9 plants analyzed) and fungal (mean: 20.9 species per sample; 22 plants analyzed) communities using culture-independent methods. Many of the identified taxa are known plant endophytes, but have not been previously found in latex. Our results suggest that Euphorbia plant latex, a putatively hostile antimicrobial environment, unexpectedly supports diverse bacterial and fungal communities. The ecological roles of these microorganisms and potential interactions with their host plants are unknown and warrant further research. © 2015 Botanical Society of America.

  13. 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

  14. 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.

  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.

  16. Adhesion mechanisms of arc-sprayed zinc on concrete

    NASA Astrophysics Data System (ADS)

    Legoux, J. G.; Dallaire, S.

    1995-12-01

    Arc-sprayed zinc coatings can provide cathodic protection against corrosion to steel reinforcement in concrete. Because the adhesion of sprayed zinc on concrete is of major concern, the parameters related to zinc deposition and concrete preparation that affect the adhesion have been previously investigated. However, little attention has been devoted to determining which basic mechanisms are responsible for the adhesion of molten zinc on concrete. Because the interaction of molten zinc droplets with the concrete surface is considered physical, this paper is focused on the influence of surface patterns on the adhesion of arc-sprayed zinc coatings. Concrete surfaces were characterized by image analysis and profilometry techniques to ascertain which surface pattern or components could affect the adhesion of zinc. A modified root mean square (RMS) surface roughness was derived to take into account the different surface mor-phologies seen by sprayed zinc droplets. This modified RMS surface roughness was found to be directly related to the measured bond strength of arc-sprayed zinc on concrete. After the surface profile on con-crete is measured and the surface constituents are considered, the bond strength of arc-sprayed metals on concrete can be forecasted for given deposition parameters.

  17. Improvement of cement concrete strength properties by carbon fiber additives

    NASA Astrophysics Data System (ADS)

    Nevsky, Andrey; Kudyakov, Konstantin; Danke, Ilia; Kudyakov, Aleksandr; Kudyakov, Vitaly

    2016-01-01

    The paper presents the results of studies of fiber-reinforced concrete with carbon fibers. The effectiveness of carbon fibers uniform distribution in the concrete was obtained as a result of its preliminary mechanical mixing in water solution with chemical additives. Additives are to be used in the concrete technology as modifiers at initial stage of concrete mix preparing. The technology of preparing of fiber-reinforced concrete mix with carbon fibers is developed. The superplasticizer is based on ether carboxylates as a separator for carbon fibers. The technology allows increasing of concrete compressive strength up to 43.4% and tensile strength up to 17.5% as well as improving stability of mechanical properties.

  18. 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

  19. A hooded exposure chamber method for semiquantitative latex aeroallergen challenge.

    PubMed

    Kurtz, K M; Hamilton, R G; Schaefer, J A; Adkinson, N F

    2001-01-01

    Allergen challenges are useful in adjudicating discordant clinical histories and skin test responses, serologic test responses, or both, as well as in determining the degree of allergic reactivity. Latex allergen challenges have been developed but have limitations that reduce their usefulness. We sought to develop a novel hooded exposure chamber (HEC) system to allow safe, sensitive, and semiquantitative evaluation of respiratory latex allergy. The HEC system uses an impinger to produce a particle cloud of cornstarch isolated from powdered latex gloves. The particles are air driven into a face shield and hood to simultaneously challenge the subject's conjunctiva, nose, and lungs during 3 minutes of normal tidal breathing. A cloud of respirable latex allergen-associated cornstarch particles (LACs) is consistently produced in the HEC during challenges. Twenty-three subjects with latex allergy (history and positive skin test response, positive serologic test response, or both) and 3 atopic control subjects not allergic to latex (history and negative skin test response, negative serologic test response, or both) were sequentially exposed to air, control cornstarch, and then progressive 2-fold increments of LACs in a single-masked fashion. A positive challenge result was defined as (1) a peak expiratory flow rate decline of 15% or greater from baseline; (2) a peak expiratory flow rate decline of 10% or greater and an increase of either the rhinoconjunctivitis or chest symptom score scale of 3 or more points from baseline; or (3) an increase of either the rhinoconjunctivitis or chest symptom score scale of 6 or more points from baseline. Twenty-two of the 23 subjects with latex allergy reached threshold criteria for a positive challenge at LAC titers of 1:8 or greater, giving a sensitivity of 0.96. Challenge endpoints were moderately corrected with skin test sensitivity (r (s) = -0.55, P =.01) but not with RAST reactivity. None of the 3 control subjects responded to LACs

  20. Interaction processes at the concrete-bentonite interface after 13 years of FEBEX-Plug operation. Part I: Concrete alteration

    NASA Astrophysics Data System (ADS)

    Alonso, María Cruz; García Calvo, José Luis; Cuevas, Jaime; Turrero, María Jesús; Fernández, Raúl; Torres, Elena; Ruiz, Ana I.

    2017-06-01

    This paper evaluates the modifications created in the concrete of the FEBEX shotcreted concrete plug after 13 years in the Grimsel Test Site conditions. During this time the concrete interacted with granite groundwater and also with bentonite porewater at the concrete/bentonite contact. Three long cores and 6 small cores from different parts of the concrete plug were evaluated. Mechanical performance was not modified during this time but hydraulic conductivity increased. The main transport mechanisms involved in the alteration of the concrete were groundwater flow from the host rock to the concrete and diffusion at the concrete/bentonite interface. Leaching occurred in the concrete parts near the host rock due to the action of granite water with further portlandite dissolution. The joint action of granite groundwater and bentonite porewater has caused many changes to the concrete matrix which was located at a depth lower than 5 cm from the bentonite-concrete interface. In the first centimetre C-S-H was significantly altered, incorporating elements like Al, S and Mg which change the initial microstructure by loss of compactness. The ettringite content was very high along the length of the concrete plug due to the shotcreting technique which made use of accelerator additives that caused the formation of ettringite. An increase in the ettringite content is also shown near the bentonite barrier. Therefore, sulphate diffused from the bentonite into the concrete, causing the massive formation of new ettringite. Chloride also diffused from the bentonite barrier deeper into the concrete by up to 4-5 cm from where the formation of Friedel's salt was detected.

  1. 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

  2. Reinforced Concrete Modeling

    DTIC Science & Technology

    1982-07-01

    AFWL-TR-82-9 AFWL-TR-82-9 REINFORCED CONCRETE MODELING H. L. Schreyer J. W. Jeter, Jr. New Mexico Engineering Reseprch Institute University of New...Subtitle) S. TYPE OF REPORT & PERIOD COVERED REINFORCED CONCRETE MODELING Final Report 6. PERFORMING OtG. REPORT NUMBER NMERI TA8-9 7. AUTHORg) S...loading were identified and used to evaluate current concrete models . Since the endochronic and viscoplastic models provide satisfactory descriptions

  3. Beta Bremsstrahlung dose in concrete shielding

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Chandrika, B. M.; Rudraswamy, B.; Sankarshan, B. M.

    2012-05-01

    In a nuclear reactor, beta nuclides are released during nuclear reactions. These betas interact with shielding concrete and produces external Bremsstrahlung (EB) radiation. To estimate Bremsstrahlung dose and shield efficiency in concrete, it is essential to know Bremsstrahlung distribution or spectra. The present work formulated a new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides (32P, 89Sr, 90Sr-90Y, 90Y, 91Y, 208Tl, 210Bi, 234Pa and 40K) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. The Bremsstrahlung yield in concrete due to 90Sr-90Y is higher than those of other given nuclides. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Zmod) and Seltzer's data, where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear shielding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study.

  4. Experimental study on the effect of volcanic residue on the performance of recycled lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Xiao, Li-guang; Li, Ji-heng; Liu, Qing-shun

    2017-08-01

    Recycled lightweight aggregate concrete prepared with waste brick recycled light aggregate has high water absorption, large apparent density and poor frost resistance. The technical measures of regen-erating lightweight aggregate concrete with modified waste bricks from volcanic slag are put forward. The effects of volcanic slag on the properties of waste lightweight aggregate concrete were studied. The experi-mental results show that volcanic slag can significantly reduce the apparent density of recycled lightweight aggregate concrete and improve its frost resistance.

  5. Effect of latex glove contamination on bond strength.

    PubMed

    Roberts, Howard W; Bartoloni, Joseph

    2002-01-01

    This study examined the effect of powdered and powder-free latex glove contamination on bond strength. Sixty caries-free human third molars were mounted in acrylic, sectioned with a diamond saw to expose a flat occlusal dentin surface, and finished with 400- and 600-grit silicon carbide paper. Teeth were assigned to one of 5 groups: 1) no latex glove contamination (control); 2) powdered latex glove contamination before etching; 3) powder-free latex glove contamination before etching; 4) powdered latex glove contamination after dentin bonding agent application but prior to resin composite placement; 5) powder-free latex glove contamination after dentin bonding agent application but prior to resin composite placement. Excite dentin bonding agent was used per manufacturer's instructions. Z-250 resin composite was applied in 2- x 2-mm increments using a split Teflon mold, each light cured for 20 s. Bonded samples were thermocycled 500 cycles between 5 degrees C and 55 degrees C water baths. Specimens were stored in 37 degrees C distilled water. One-week shear bond strength values were determined using a Tinius Olsen testing machine at a crosshead speed of 0.5 mm/min. Results were analyzed with one-way ANOVA (alpha = 0.05). No significant difference (p = 0.47) in bond strength was found between the experimental groups and the control. Groups 1, 2, 3, and 5 exhibited predominantly mixed failures while the majority of samples in Group 4 showed adhesive failures. Under the conditions of this study, contamination of dentin by powdered or powder-free latex gloves did not significantly affect bond strength. Future research should be directed toward evaluating the effects of dentin contamination on bond strength of other bonding agents and include ultrastuctural examination in determining what role, if any, powder plays as a contaminant.

  6. Latex medical gloves: time for a reappraisal.

    PubMed

    Palosuo, Timo; Antoniadou, Irini; Gottrup, Finn; Phillips, Peter

    2011-01-01

    Many hospitals have implemented policies to restrict or ban the use of devices made of natural rubber latex (NRL) in healthcare as precautionary measures against the perceived risk of NRL allergy. Changes in glove technology, progress in measuring the specific allergenic potential of gloves and a dramatic decrease in the prevalence of NRL allergies after interventions and education prompted us to revisit the basis for justifiable glove selection policies. The published Anglophone literature from 1990 to 2010 was reviewed for original articles and reviews dealing with the barrier and performance properties of NRL and synthetic gloves and the role of glove powder. The review shows that NRL medical gloves, when compared with synthetic gloves, tend to be stronger, more flexible and better accepted by clinicians. The introduction of powder-free gloves has been associated with reductions in protein content and associated allergies. Recently, new methods to quantify clinically relevant NRL allergens have enabled the identification of gloves with low allergenic potential. The use of low-protein, low-allergenic, powder-free gloves is associated with a significant decrease in the prevalence of type I allergic reactions to NRL among healthcare workers. Given the excellent barrier properties and operating characteristics, dramatically reduced incidences of allergic reactions, availability of specific tests for selection of low-allergen gloves, competitive costs and low environmental impact, the use of NRL gloves within the hospital environment warrants reappraisal.

  7. Extraction and characterization of latex and natural rubber from rubber-bearing plants.

    PubMed

    Buranov, Anvar U; Elmuradov, Burkhon J

    2010-01-27

    Consecutive extraction of latex and natural rubber from the roots of rubber-bearing plants such as Taraxacum kok-saghyz (TKS), Scorzonera tau-saghyz (STS), and Scorzonera Uzbekistanica (SU) were carried out. Latex extraction was carried via two methods: Blender method and Flow method. The results of latex extraction were compared. Cultivated rubber-bearing plants contained slightly higher latex contents compared to those from wild fields. Several creaming agents for latex extraction were compared. About 50% of total natural rubber was extracted as latex. The results of the comparative studies indicated that optimum latex extraction can be achieved with Flow method. The purity of latex extracted by Blender method ( approximately 75%) was significantly lower than that extracted by Flow method (99.5%). When the latex particles were stabilized with casein, the latex was concentrated significantly. Through concentrating latex by flotation, the latex concentration of 35% was obtained. Bagasse contained mostly solid natural rubber. The remaining natural rubber in the bagasse (left after the latex extraction) was extracted using sequential solvent extraction first with acetone and then with several nonpolar solvents. Solid natural rubber was analyzed for gel content and characterized by size exclusion chromatography (SEC) for molecular weight determinations. SEC of solid natural rubber has shown that the molecular weight is about 1.8E6 and they contain less gel compared to TSR20 (Grade 20 Technically Specified Rubber), a commercial natural rubber from Hevea brasiliensis.

  8. 51. DETAIL VIEW OF VIVIANNA ERA CONCRETE HOUSE WITH CONCRETE ...

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

    51. DETAIL VIEW OF VIVIANNA ERA CONCRETE HOUSE WITH CONCRETE PATIO SLAB LOOKING SOUTHWEST. NOTICE MINE WORKINGS BACKGROUND LEFT. - Mariscal Quicksilver Mine & Reduction Works, Terlingua, Brewster County, TX

  9. Comparative transcriptome analysis of latex from rubber tree clone CATAS8-79 and PR107 reveals new cues for the regulation of latex regeneration and duration of latex flow.

    PubMed

    Chao, Jinquan; Chen, Yueyi; Wu, Shaohua; Tian, Wei-Min

    2015-04-18

    Rubber tree (Hevea brasiliensis Muell. Arg.) is the primarily commercial source of natural rubber in the world. Latex regeneration and duration of latex flow after tapping are the two factors that determine rubber yield of rubber tree, and exhibit a huge variation between rubber tree clones CATAS8-79 and PR107. To dissect the molecular mechanism for the regulation of latex regeneration and duration of latex flow, we sequenced and comparatively analyzed latex of rubber tree clone CATAS8-79 and PR107 at transriptome level. More than 26 million clean reads were generated in each pool and 51,829 all-unigenes were totally assembled. A total of 6,726 unigenes with differential expression patterns were detected between CATAS8-79 and PR107. Functional analysis showed that genes related to mass of categories were differentially enriched between the two clones. Expression pattern of genes which were involved in latex regeneration and duration of latex flow upon successive tapping was analyzed by quantitative PCR. Several genes related to rubber biosynthesis, cellulose and lignin biosynthesis and rubber particle aggregation were differentially expressed between CATAS8-79 and PR107. This is the first report about probing latex regeneration and duration of latex flow by comparative transcriptome analysis. Among all the suggested factors, it is more important that the level of endogenous jasmonates, carbohydrate metabolism, hydroxymethylglutaryl-CoA reductase (HMGR) and Hevea rubber transferase (HRT) in mevalonate (MVA) parthway for latex regeneration while the level of endogenous ethylene (ETH), lignin content of laticifer cell wall, antioxidants and glucanases for the duration of latex flow. These data will provide new cues for understanding the molecular mechanism for the regulation of latex regeneration and duration of latex flow in rubber tree.

  10. 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.

  11. 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.

  12. Antinociceptive activity of Calotropis procera latex in mice.

    PubMed

    Soares, Paula Matias; Lima, Silvane R; Matos, Samara G; Andrade, Marcelo M; Patrocínio, Manoel C A; de Freitas, Cleverson D T; Ramos, Márcio V; Criddle, David N; Cardi, Bruno A; Carvalho, Krishnamurti M; Assreuy, Ana Maria S; Vasconcelos, Silvânia M M

    2005-05-13

    This work evaluated the antinociceptive effect of proteins from the Calotropis procera (Asclepiadaceae) latex using three different experimental models of nociception in mice. The latex protein fraction administered intraperitoneally in male mice at the doses of 12.5, 25 and 50 mg/kg showed the antinociceptive effect in a dose dependent manner compared to the respective controls in all assays. Inhibitions of the acetic acid-induced abdominal constrictions were observed at the doses of 12.5 (67.9%), 25 (85%) and 50 (99.5%) mg/kg compared to controls. Latex protein at the doses of 25 (39.8%; 42%) and 50 mg/kg (66.6%; 99.3%) reduced the nociception produced by formalin in the 1st and 2nd phases, respectively, and this effect was not reversed by pretreatment with naloxone (1 mg/kg). In the hot plate test, an increase of the reaction time was observed only at 60 min after the treatment with latex at the doses of 25 (79.5%) and 50 (76.9%) mg/kg, compared to controls and naloxone was ineffective to reverse the effect. It was concluded that the protein fraction derived from the whole latex of Calotropis procera possesses antinociceptive activity, which is independent of the opioid system.

  13. Detection of staphylococcal exfoliative toxin by slide latex agglutination.

    PubMed Central

    Murono, K; Fujita, K; Yoshioka, H

    1988-01-01

    A simple and rapid method in which slide latex agglutination was used was developed to detect the exfoliative toxin (ET) elaborated by clinical isolates. ET types A and B (ET-A and ET-B) were purified by plate gel isoelectrofocusing, and anti-ET sera were obtained by immunizing rabbits. A specific immunoglobulin G antitoxin was then prepared from the immunized rabbit sera by fast protein liquid chromatography, and latex particles were coated with the antitoxin. Of 74 staphylococcal strains isolated from patients with staphylococcal scalded skin syndrome, 61 strains were found to produce ET by the newborn mouse bioassay. All 61 strains were shown to be positive for ET-A and ET-B production by the slide latex agglutination method. The lowest concentration of ETs detected by the latex agglutination method was 0.5 microgram/ml, which was much lower than that detected by the double immunodiffusion method, with a sensitivity of 50 micrograms/ml. It is crucial to prove ET production by clinical isolates for the diagnosis and surveillance of staphylococcal scalded skin syndrome. The latex agglutination method is a sensitive, simple, and rapid test which can be used as an alternative to the newborn mouse bioassay. Images PMID:3343322

  14. [Latex allergy and cross-reactions: a new threat?].

    PubMed

    Stevens, W

    2000-01-01

    Allergy to latex proteins has become an important problem, especially in the medical profession, but also in people who have regularly contact with latex products. The responsible antigens are proteins, which are present in the natural rubber latex (NRL), extracted from Hevea brasiliensis. These proteins are important in the synthesis of rubber and in the defence of the plant against external noxes (pathogenesis related proteins). Life threathening reactions occur more frequently in the operating theatre. Sensitisation can occur via different routes (aerogen, skin, parenteral, ...) but aerogenic sensitisation seems to be very important. Starch particles are important vectors of the antigens. Diagnosis is made via history, confirmed by demonstration of specific IgE via skin test (in vivo) or via an in vitro method (e.g. CAP, ELISA). Immunological cross reactions are very frequent with other plant or fruit allergens but cross allergy is less frequent (sensitivity and specificity of the in vitro test varies considerably depending on the nature of the fruit or vegetable investigated). There is also a cross reactivity with Ficus. Prevention with latex allergens becomes primordial in hospital settings. The industry is aware of the problem and produces more and more synthetic latex products.

  15. Investigating the rheological properties of native plant latex

    PubMed Central

    Bauer, Georg; Friedrich, Christian; Gillig, Carina; Vollrath, Fritz; Speck, Thomas; Holland, Chris

    2014-01-01

    Plant latex, the source of natural rubber, has been of interest to mankind for millennia, with much of the research on its rheological (flow) properties focused towards industrial application. However, little is known regarding the rheology of the native material as produced by the plant, a key factor in determining latex's biological functions. In this study, we outline a method for rheological comparison between native latices that requires a minimum of preparatory steps. Our approach provides quantitative insights into the coagulation mechanisms of Euphorbia and Ficus latex allowing interpretation within a comparative evolutionary framework. Our findings reveal that in laboratory conditions both latices behave like non-Newtonian materials with the coagulation of Euphorbia latex being mediated by a slow evaporative process (more than 60 min), whereas Ficus appears to use additional biochemical components to increase the rate of coagulation (more than 30 min). Based on these results, we propose two different primary defensive roles for latex in these plants: the delivery of anti-herbivory compounds (Euphorbia) and rapid wound healing (Ficus). PMID:24173604

  16. Investigating the rheological properties of native plant latex.

    PubMed

    Bauer, Georg; Friedrich, Christian; Gillig, Carina; Vollrath, Fritz; Speck, Thomas; Holland, Chris

    2014-01-06

    Plant latex, the source of natural rubber, has been of interest to mankind for millennia, with much of the research on its rheological (flow) properties focused towards industrial application. However, little is known regarding the rheology of the native material as produced by the plant, a key factor in determining latex's biological functions. In this study, we outline a method for rheological comparison between native latices that requires a minimum of preparatory steps. Our approach provides quantitative insights into the coagulation mechanisms of Euphorbia and Ficus latex allowing interpretation within a comparative evolutionary framework. Our findings reveal that in laboratory conditions both latices behave like non-Newtonian materials with the coagulation of Euphorbia latex being mediated by a slow evaporative process (more than 60 min), whereas Ficus appears to use additional biochemical components to increase the rate of coagulation (more than 30 min). Based on these results, we propose two different primary defensive roles for latex in these plants: the delivery of anti-herbivory compounds (Euphorbia) and rapid wound healing (Ficus).

  17. Latex film morphology and electrical potential pattern dependence on serum components: a scanning probe microscopy study.

    PubMed

    Keslarek, Amauri José; Costa, Carlos Alberto Rodrigues; Galembeck, Fernando

    2002-11-01

    Dry films formed by surfactant-stabilized, peroxide-initiated styrene-butyl acrylate latex were examined by atomic and electric force microscopy (AFM and EFM). The effects of latex serum components on the films were observed by subjecting the latex to extensive dialysis prior to film formation, and comparing the results to as-prepared latex. The films formed with the dialyzed latex are smoother (as evidenced by roughness and fractal dimension measurements) than the films from the as-prepared latex, but they display large electric force gradients between neighboring domains. The films made with the as-prepared latex have the highest electric uniformity, with a maximum potential variation lower than 80 mV, while this reaches 200 mV in the dialyzed latex film.

  18. HIGH-COMPRESSIVE-STRENGTH CONCRETE.

    DTIC Science & Technology

    CONCRETE , COMPRESSIVE PROPERTIES), PERFORMANCE(ENGINEERING), AGING(MATERIALS), MANUFACTURING, STRUCTURES, THERMAL PROPERTIES, CREEP, DEFORMATION, REINFORCED CONCRETE , MATHEMATICAL ANALYSIS, STRESSES, MIXTURES, TENSILE PROPERTIES

  19. Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Latex Admixtures for Portland Cement Concrete and Mortar.

    DTIC Science & Technology

    1986-07-01

    acetate (PVa) ni CHI -CH ’V.w (CHI CH)n’ w I Polymerasation I OOCCI4,. OOCC143 monomer polymer ( vinyl acetate ) Opva) Polyethylene n CH...COOCI~s COOCH, mothylmothacrytato polymettylnwthecrylate Ethylene vinyl ametate (EVA) n CH-CH2 + m CHaCM OOCCHa ethylene monomer vinyl acetate monomer ...OOCCHS ethylene- vinyl acetate copolymer Styron..butadone 011111) CHi - CHI n 6+mCH-CH -CH-CH2 atyran. butadlene -. CM, CHI’

  20. 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.

  1. 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%.

  2. 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.

    1987-01-01

    Monodisperse latex particles developed by seeded emulsion polymerization on various Space Shuttle flights are analyzed. The flight hardware was composed of a monodisperse latex reactor and a support electronics package, and the particles were examined by optical microscopy and TEM. Data on the particle size distributions, larger and smaller off-size particles, and conversion-time curves for the particles are examined and compared to ground-based results. It is observed that the ground-based polymerizations have more coagulum than the flight polymerizations; the flight latex particles have narrower size distributions than the ground particles; and the number of off-size larger particles in the flight particles is smaller than in the ground data.

  3. Identification and characterization of Euphorbia nivulia latex proteins.

    PubMed

    Badgujar, Shamkant B; Mahajan, Raghunath T

    2014-03-01

    The protein profile of latex of Euphorbia nivulia Buch.-Ham. is established. Three new proteins viz., Nivulian-I, II and III have been purified to homogeneity from the latex. The relative molecular masses of Nivulian-I, II and III are 31,486.985, 43,670.846 and 52,803.470 Da respectively. Nivulian-I is a simple type of protein while Nivulian-II and III are glycoproteins. Peptide mass fingerprint analysis revealed peptides of these proteins match with Tubulin alpha-1 chain of Eleusine indica, Maturase K of Banksia quercifolia and hypothetical protein of Zea mays respectively. Tryptic digestion profile of Nivulian-I, II and III, infer the exclusive nature of latex origin proteins and may be new and are additive molecules in the dictionaries of phytoproteins or botany. This is the first of its kind, regarding characterization and validation of Nivulian-I, II and III with respect to peptide sequencing.

  4. Controllable preparation of high-yield magnetic polymer latex.

    PubMed

    Wu, Chun-Chao; Kong, Xiang-Ming; Yang, Hai-Long

    2011-09-01

    In order to overcome the low conversion and complex post-treatment, four different polymerization procedures were adopted to prepare the magnetic polymer latexes. The results clearly show that the strategy using magnetic emulsion template-dosage is the most effective and feasible. Based on the optimized procedure, various factors including the type of initiators such as oil soluble initiator, water soluble initiator, redox initiator system, crosslinking agent, functional monomers etc. were systematically studied. Magnetic polymer latex with high monomer conversion of 83% and high magnet content of 31.8% was successfully obtained. Besides, core-shell structured magnetic polymer latex with good film forming property was also prepared, which is promising for potential applications such as magnetic coatings and modification of cementitious materials with controlled polymer location.

  5. Filtering KPNO \\LaTeX\\ Observing Proposals with Perl

    NASA Astrophysics Data System (ADS)

    Bell, David J.

    An automated observing proposal processing system has been in use at KPNO during the past three years. \\LaTeX\\ proposal templates are filled out by users and sent to KPNO via electronic mail. Observer and proposal information fields in these files are well-marked with \\LaTeX\\ tags, thus allowing automated extraction and importation to observatory databases. A significant complication of this process is that although the fields are well-marked, the information they contain often arrives in a variety of formats that must be recognized and standardized. Perl's regular expression and text manipulation capabilities make it an excellent tool for performing these functions. This paper outlines the filtering system in use at KPNO and discusses some of the ways Perl has proven useful for parsing \\LaTeX\\ documents.

  6. 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.

    1987-01-01

    Monodisperse latex particles developed by seeded emulsion polymerization on various Space Shuttle flights are analyzed. The flight hardware was composed of a monodisperse latex reactor and a support electronics package, and the particles were examined by optical microscopy and TEM. Data on the particle size distributions, larger and smaller off-size particles, and conversion-time curves for the particles are examined and compared to ground-based results. It is observed that the ground-based polymerizations have more coagulum than the flight polymerizations; the flight latex particles have narrower size distributions than the ground particles; and the number of off-size larger particles in the flight particles is smaller than in the ground data.

  7. 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...

  8. 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...

  9. 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....

  10. 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....

  11. 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....

  12. Definition of fibronectin-mediated uptake of gelatinized latex by liver slices and macrophages.

    PubMed

    Molnar, J; Galles, M; Beezhold, D; Lai, M Z; Ku, C S; Van Alten, P J

    1987-10-01

    These studies show that both liver slices and macrophages carried out fibronectin concentration-dependent uptake of 125I-labeled gelatin-coated latex (test latex). Lack of phagocytosis of test latex by liver slices was shown directly by electron microscopy and indirectly by trypsin treatment, which caused the release of all test latex taken up in response to fibronectin. Inhibitors of phagocytosis did not alter this uptake. On the other hand, trypsin released only a portion of test latex from macrophages. Inhibitors of phagocytosis did not effect the released radioactive particles from macrophages but greatly reduced the trypsin-resistant radioactivity, taken as representing phagocytized particles. Opsonization of test latex with fibronectin did not require heparin but its association with liver slices occurred only in the presence of heparin. Macrophages, however, readily bound and internalized the opsonized test latex and heparin only potentiated these reactions. Gelatin competed with test latex for fibronectin for opsonization, but did not inhibit binding and phagocytosis of fibronectin-test latex complexes. Finally, soluble fibronectin-gelatin complexes did not compete for binding and phagocytosis of fibronectin-test latex complexes. Thus, fibronectin concentrated on the surface of latex is preferred for interaction with the fibronectin receptor of macrophages. Gelatin, however, was not essential for this reaction, because fibronectin directly coupled to latex was also readily taken up.

  13. Evaluation of hemostatic activity of latex from three Euphorbiaceae species.

    PubMed

    Badgujar, Shamkant B

    2014-01-01

    Latices from several plant species of Euphorbiaceae family have been traditionally applied over fresh cuts to stop bleeding and subsequently applied over wounds to enhance healing process. The latex arrested bleeding from fresh wounds by reducing bleeding and whole blood coagulation time which are important indices of hemostatic activity. It has been accepted that hemostatic activity is due to the proteolytic fraction of plant latices. Thus, the present study aimed to assess the clot inducing properties of three Euphorbiaceae plants viz., Euphorbia nivulia Buch.-Ham., Pedilanthus tithymaloides (L.) Poit and Synadenium grantii Hook F. In the present study, various proteolytic activities namely protease, gelatinase, milk clotting and whole blood clotting assay of the enzyme fraction of latices of Euphorbia nivulia, Pedilanthus tithymaloides and Synadenium grantii have been investigated. The inhibition profile of protease specific inhibitors was assessed. Also, the effects of protein fractions were studied using bleeding/clotting time test of fresh experimentally-induced wounds in mice. Euphorbia nivulia latex protease has noticeable blood clotting activity followed by Pedilanthus tithymaloides and Synadenium grantii. Stem latex protease of Pedilanthus tithymaloides exhibits superior procoagulant activity in different mammal's blood samples viz., Capra hircus, Bubalus bubalis, Ovibos moschatus and Bos indicus. Blood sample of ox was the most sensitive to latex protease than other mammal's blood. Concomitantly, the plant latex protease could significantly reduce whole blood clotting time of human and mice blood samples. The protease fraction of latices of Euphorbia nivulia, Pedilanthus tithymaloides and Synadenium grantii possesses phytoconstituents capable of arresting wound bleeding, and accelerating whole blood coagulation process. It suggests good potentiality for use of latex proteases in wound management. Also, the finding of this study showed that the protease

  14. 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.

  15. 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

  16. Crotogossamide, a cyclic nonapeptide from the latex of Croton gossypifolius.

    PubMed

    Quintyne-Walcott, Simone; Maxwell, Anderson R; Reynolds, William F

    2007-08-01

    A new cyclic nonapeptide, crotogossamide (1), was isolated from the latex of Croton gossypifolius. Its structure was elucidated by use of 1D and 2D NMR and MS and by hydrolysis followed by GC-MS analysis as cyclo(-Gly(1)-Ala(2)-Ser(3)-Gly(4)-Leu(5)-Asn(6)-Gly(7)-Ile(8)-Phe(9)-). This is the first report of a cyclic peptide from a Croton species. The known flavonoids kaempferol 3-O-rhamnopyranoside, quercitrin, and myricitrin were also isolated from the plant latex.

  17. 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.

  18. Latex condom deterioration accelerated by environmental factors: I. Ozone.

    PubMed

    Clark, L J; Sherwin, R P; Baker, R F

    1989-03-01

    Commercial non-lubricated latex condoms were unpackaged and exposed in an environmental chamber to ozone levels (0.3 ppm) commonly present in urban smog conditions. Deterioration was observed by scanning electron microscopy after 18 hours exposure. Loss of mechanical strength was quantitated by measurement of the air pressures necessary to burst the condom and volumes at burst. After 24 hours exposure to ozone the latex surface was covered with craters and after 48 hours the pressure required to burst the condom was 44% that of control samples. Data suggest the need for study of the effectiveness of lubrication and packaging in protecting condoms from environmental factors which may accelerate deterioration.

  19. 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.

  20. 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.

  1. 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.

  2. 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. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Effect of insulating concrete forms in concrete compresive strength

    NASA Astrophysics Data System (ADS)

    Martinez Jerez, Silvio R.

    The subject presented in this thesis is the effect of Insulating Concrete Forms (ICF's) on concrete compressive strength. This work seeks to identify if concrete cured in ICF's has an effect in compressive strength due to the thermal insulation provided by the forms. Modern construction is moving to energy efficient buildings and ICF's is becoming more popular in new developments. The thesis used a concrete mixture and a mortar mixture to investigate the effects of ICF's on concrete compressive strength. After the experimentations were performed, it was concluded that the ICF's do affect concrete strength. It was found that the forms increase concrete strength without the need for additional curing water. An increase of 50% in strength at 56 days was obtained. It was concluded that the longer concrete cures inside ICF's, the higher strength it reaches, and that ICF's effect on concrete strength is proportional to volume of concrete.

  4. Pharmacologic characterization of latex extracts by isolated guinea pig tracheal tissue.

    PubMed

    Schachter, E N; Zuskin, E; Rienzi, N; Goswami, S; Maayani, S

    1998-01-01

    Latex manufacturing workers are exposed to a heterogeneous aerosol of organic compounds. Previous studies of latex workers involved in glove production indicate that these individuals are at risk of developing respiratory symptoms and impaired lung function. The effect of latex extracts on isolated guinea pig tracheal smooth muscles was studied using latex water-soluble extracts obtained at different stages of the industrial process. Latex extracts were prepared as a 1:10 (w/v) solution. Dose-related contractions of nonsensitized guinea pig trachea were demonstrated using two latex extracts (latex 1 and latex 2). Latex 1 was prepared from the native latex and latex 2 from a processed form of latex which was relatively free of soluble proteins. Pharmacologic studies were performed by pretreating guinea pig tracheal tissue with drugs known to modulate smooth muscle contraction: atropine, indomethacin, pyrilamine, nordihydroguaiacetic acid, acivicin, trimethobenzoic acid and capsaicin. Constrictor effects of the dust extracts were inhibited by a wide variety of these agents. Atropine consistently and strikingly reduced the contractile effects of these extracts. This observation may suggest an interaction of the extracts with parasympathetic nerves or more directly with muscarinic receptors. Inhibition of contraction by blocking other mediators was less effective and varied with the dust extract. Pretreatment with capsaicin did not change the constrictor effects of latex 1 but enhanced the effects of latex 2. Depletion of neuropeptides, however, did not reduce the constrictor effect. We suggest that latex extracts cause dose-related airway smooth muscle constriction by nonimmunological mechanisms involving a variety of airway mediators and possibly cholinergic receptors. This effect is not dependent on the presensitization of guinea pigs.

  5. 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.

  6. Electrokinetic Strength Enhancement of Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E. (Inventor)

    2016-01-01

    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.

  7. 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.

  8. Prevalence of Trichomonas vaginalis infection among Egyptian women using culture and Latex agglutination: cross-sectional study.

    PubMed

    Mahmoud, Ahmed; Sherif, Nadine A; Abdella, Rana; El-Genedy, Amira R; El Kateb, Abdalla Y; Askalani, Ahmed Nh

    2015-01-01

    This is a cross-sectional study carried out in the Obstetrics and Gynecology Department at Kasr Al- Ainy Cairo University Hospitals. One thousand female patients in the child bearing period (age 18-45 yrs) were included in this study. These females were non-pregnant and non-menstruating with no douching or intercourse for at least 2-3 days, no use of antibiotics, anti-protozoal or steroids for the past 15 days complaining of vaginal discharge with or without itching, burning sensation or both. Vaginal swabs were obtained from all patients for examination by direct wet mount examination, Giemsa staining, Modified Diamond culture and latex agglutination test Kalon) to detect the presence of Trichomonas vaginalis infection. The prevalence of trichomonas infection was 50 cases, latex agglutination test detected 50 positive cases, 30 of which were also positive by culture, and only 10 were detected both by Giemsa staining and by wet mount. The wet mount, Giemsa staining and Kalon latex test had sensitivities of 33.3, 33.3% and 100% respectively while their specificities were 100%, 100% and 97.9% respectively. Screening tests should be done routinely to depict cases of T. vaginalis infection and should be included in the control programs of sexually transmitted infections. Although wet mount is not a sensitive method for diagnosis of T. vaginalis yet, it is a good positive one. Staining is only useful when there is heavy T. vaginalis infection. Latex agglutination is a highly sensitive, simple, rapid and cost effective test. It provides results within 2-3 minutes and it has the potential for use in screening and diagnosis of T. vaginalis infection.

  9. 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

  10. Stopped-flow kinetics of pH-responsive polyamine latexes: how fast is the latex-to-microgel transition?

    PubMed

    Morse, A J; Armes, S P; Mills, P; Swart, R

    2013-12-10

    Four poly(ethylene glycol)-stabilized polyamine latexes, namely, poly(2-vinylpyridine) (P2VP), poly(2-(tert-butylamino)ethyl methacrylate) (PTBAEMA), poly(2-(diethylamino)ethyl methacrylate) (PDEA), and poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) were prepared via emulsion copolymerization using divinylbenzene (DVB) as a cross-linker at 0.80 mol % for all formulations. According to dynamic light scattering studies, the resulting latexes were near-monodisperse and had approximately constant hydrodynamic diameters of 205-220 nm at pH 10; a latex-to-microgel transition was observed at around the respective pKa of each polyamine on addition of acid. The kinetics of swelling of each latex was investigated by the pH-jump method using a commercial stopped-flow instrument. The most rapid swelling was observed for the P2VP latex, which exhibited a characteristic swelling time (t*) of 5 ms. The corresponding t* values for PTBAEMA and PDEA were 25 and 35 ms, respectively, whereas the PDPA particles exhibited significantly slower swelling kinetics (t* = 180 ms). These t* values could not be correlated with either the latex Tg or the polyamine pKa. However, there is a positive correlation between t* and the repeat unit mass of the amine monomer, which suggests that the cationic charge density of the protonated polymer chains may influence the kinetics of swelling. Alternatively, the observed differences in swelling kinetics may simply reflect subtle differences in the DVB cross-link density, with more uniformly cross-linked latexes being capable of responding more quickly to a pH jump. The kinetics of deswelling for the corresponding microgel-to-latex transition was also briefly investigated for the PTBAEMA and P2VP particles. In both cases, much slower rates of deswelling were observed. This suggests that a latexlike "skin" is formed on the outer surface of the microgel particles during their deprotonation, which significantly retards the excretion of both salt and

  11. Health risk in hospitals through airborne allergens for patients presensitised to latex.

    PubMed

    Baur, X; Ammon, J; Chen, Z; Beckmann, U; Czuppon, A B

    1993-11-06

    Two nurses had to stop practicing because of severe work-related allergic respiratory or systemic symptoms. Both developed similar symptoms within a short time when they attended hospitals as outpatients or visitors or consulted a doctor or dentist, even when they had no direct contact with latex articles. The airborne latex allergen concentration in one room that induced symptoms was 128 ng per m3. In skinprick tests both women showed positive reactions to the phosphated cornstarch powder used to prevent latex gloves sticking together, but only when the powder had been in contact with latex. This powder seems a likely vehicle for the airborne latex allergen.

  12. Evaluation of latex reagents for rapid identification of Candida albicans and C. krusei colonies.

    PubMed Central

    Freydiere, A M; Buchaille, L; Guinet, R; Gille, Y

    1997-01-01

    A total of 322 yeast strains and yeastlike organisms belonging to the genera Candida, Cryptococcus, Geotrichum, Saccharomyces, and Trichosporon were tested with the new monoclonal antibody-based Bichro-latex albicans and Krusei color latex tests. Comparison of results with those obtained by conventional identification methods showed 100% sensitivity for both latex tests and 100% and 95% specificity for the Bichro-latex albicans and Krusei color tests, respectively. Because the test is easy to read and quick to perform, the Bichro-latex albicans test may be useful for rapid identification of Candida albicans colonies in the clinical laboratory. PMID:9157146

  13. 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.

  14. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  15. Lightweight polymer concrete composites

    SciTech Connect

    Fontana, J.J.; Steinberg, M.; Reams, W.

    1985-08-01

    Lightweight polymer concrete composites have been developed with excellent insulating properties. The composites consist of lightweight aggregates such as expanded perlites, multicellular glass nodules, or hollow alumina silicate microspheres bound together with unsaturated polyester or epoxy resins. These composites, known as Insulating Polymer Concrete (IPC), have thermal conductivites from 0.09 to 0.19 Btu/h-ft-/sup 0/F. Compressive strengths, dependent upon the aggregates used, range from 1000 to 6000 psi. These materials can be precast or cast-in-place on concrete substrates. Recently, it has been demonstrated that these materials can also be sprayed onto concrete and other substrates. An overlay application of IPC is currently under way as dike insulation at an LNG storage tank facility. The composites have numerous potentials in the construction industry such as insulating building blocks or prefabricated insulating wall panels.

  16. Concrete Block Pavements

    DTIC Science & Technology

    1983-03-01

    Calif. 42 1 •1 90 NEW LEGEND 80 A VIBORG, DENMARK, BLOCKS A VIBORG, DENMARK, ASPHALTIC CONCRETE AFTER 00 MELBOURNE, AUSTRALIA, BLOCKS VIBRATION MEAN ...the load-distributing characteristics of the Mlock pavements. *. 45 -, , - t 171 LEGENDT 0 CONCRETE BASE, MEAN OF 8 TESTS,9 KNAPTON (1978) I RANGE OF...45 to 60 min. 90. Table 11 summarizes the results of these tests. The mean penetration of water through the block pavements with a slope of I per

  17. Precast Concrete Pavements

    DTIC Science & Technology

    1981-11-01

    quirements. The concrete used low-weight sintered shale aggregate and high early-strength portland cement that obtained a 28-day compressive strength of...in- place concrete. Typical reasons suggested for precasting have included aggregate shortage, future pas.oment settlement or heaving, critical speed...pavements. Various devices such as dowel bars, tie bar, keyways, or aggregate interlock from sawn construction joints transfer a portion of the load

  18. 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.

  19. A new quantitative in vitro for the detection of latex-specific IgE antibodies.

    PubMed

    Moussadeh, M; Hamedi, N; Alem, N; Alem, M

    1999-12-01

    Immediate-type hypersensitivity to latex allergens has resulted in anaphylactic shock and death in numerous reported cases. The allergenic proteins of latex are contained within the natural rubber extract of Hevea brasiliensis and are eluted into the final product during the manufacturing process. The quantity and types of latex allergens found in different latex products depends on the manufacturing process. Not all of these allergens are available for use in the latex prick skin test, and as a result, such tests may not be conclusive. Furthermore, application of such allergens to the skin of undiagnosed hypersensitive individuals may have harmful effects on their health. Therefore, it is important to be able to utilize in vitro methods, which reliably identify latex allergy without placing hypersensitive individuals at risk. We have developed a relatively simple and new enzyme immuno-assay (EIA) method for the detection of latex allergy. This in vitro method is quantitative and allows for the classification of allergy to latex in a short time. In comparative studies, ninety-nine serum specimens with documented clinical history of latex allergy were tested by this method, and the results paralleled those of the skin prick test performed by an independent group. The data showed that the specificity and sensitivity of our assay approaches 97.5% and 100%, respectively. We conclude that, by using a simple assay, the detection of specific IgE to latex proteins may be valuable for screening individuals and for the diagnosis of allergy to latex.

  20. 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%.

  1. Electrochemical battery employing a latex bonded lead dioxide electrode

    SciTech Connect

    Bergum, B.; Bredland, A.; Paulson, J.

    1980-07-29

    An improvement in an electrochemical primary battery of the reserve type comprising an anode, an electrolyte, a separator, and a cathode, containing a lead dioxide material wherein the improvement is the material being comprised of a mixture of lead dioxide, carbon black, and butyl rubber latex.

  2. 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...

  3. 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.

  4. 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.…

  5. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  7. 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.…

  8. Latex use as an occlusive membrane for guided bone regeneration.

    PubMed

    Ereno, Cibele; Guimarães, Sérgio A Catanzaro; Pasetto, Silvana; Herculano, Rondinelli Donizetti; Silva, Cecília Pereira; Graeff, Carlos F O; Tavano, Orivaldo; Baffa, Oswaldo; Kinoshita, Angela

    2010-12-01

    Latex extracted from Hevea brasiliensis was used as an occlusive membrane for guided bone regeneration. Twenty-four rabbits were divided in two groups: treated and control group. Critical size bone defects (2 cm × 1 cm) were surgically made in the rabbit calvarium. Two latex membranes were implanted in each animal of the treated group, whereas the control defect was filled only with autogenous blood clot. After 15, 30, 60, and 120 days, animals from each group were euthanized, and the samples with regenerated bone were removed. No signs of allergy or rejection were noticed around the calvarial bone defect of the treated group. In the histological analysis, no foreign body inflammatory reaction was observed in the adjacent tissues in contact with the membranes demonstrating that latex can be used at injured sites as an aid in the healing process. Histological analysis, digital radiography, and electron spin resonance were used to evaluate the progress of bone repair. The results show significant differences between groups (p < 0.05) suggesting that latex membranes accelerates healing in critical bone defects.

  9. Latex of "coroa de cristo" (Euphorbia splendens): an effective molluscicide.

    PubMed

    de Vasconcellos, M C; Schall, V T

    1986-01-01

    An aqueous solution of the latex of "coroa de cristo" (Euphorbia splendens var. hislopii) showed molluscicide action (LD90) at a concentration lower than 0.5 ppm on Biomphalaria glabrata and B. tenagophila reared in laboratory and at a concentration lower than 4.0 ppm for field B. tenagophila.

  10. 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.

  11. Production of Large-Particle-Size Monodisperse Latexes in Microgravity

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, M.

    1985-01-01

    A latex is a suspension of very tiny (micrometer-size) plastic spheres in water, stabilized by emulsifiers. The growth of billions of these tiny plastic spheres to sizes larger than can be grown on Earth is attempted while keeping all of them exactly the same size and perfectly spherical. Thus far on several of the Monodisperse Latex Reactor (MLR) flights, the latex spheres have been returned to Earth with standard deviations of better than 1.4%. In microgravity the absence of buoyancy effects has allowed growth of the balls up to 30 micrometers in diameter thus far. The MLR has now flown 5 times on the Shuttle. The MLR has now produced the first commercial space product; that is the first commercial material ever manufactured in space and marketed on Earth. Once it is demonstrated that these large-size-monodisperse latexes can be routinely produced in quantity and quality, they can be marketed for many types of scientific applications. They can be used in biomedical research for such things as drug carriers and tracers in the body, human and animal blood flow studies, membrane and pore-sizing in the body, and medical diagnostic tests.

  12. Latex allergies and adverse reactions: a review of the literature.

    PubMed

    Weesner, B W

    1997-04-01

    In the last few years, the allergenic potential of latex has been receiving greater attention. While latex allergies have been widely reported in the literature, the prevalence and severity have rapidly increased in the last few years. The role of rubber in the prevention of HIV infection has played a part in recognizing the allergenic potential, as with increased emphasis on infection control in the dental office has come an increase in complaints of adverse reactions to surgical gloves. A review of the literature reveals latex allergy problems to be not confined to gloves, but to articles of clothing, rubber dam material, and other latex-containing materials. Life-threatening cases have been reported. Little information in the literature concerns the extent of the problem among dental personnel. The dental professional may be faced with not only discomfort for the dental staff, but also compromising reactive possibilities in certain patients. There is a need for development of alternative protective products for the dental office, since elimination of barrier protection is not a viable alternative to infection control.

  13. Pilot scale experiments on radiation vulcanization of NR latex

    NASA Astrophysics Data System (ADS)

    Ridwan, M.

    The potential of irradiated latex as raw material of commercial use is under testing on pilot plant scale in Indonesia which has 225 kCi Co-60 irradiation facility and can irradiate 1000 tonnes of centrifuged latex per annum. The facility was jointly designed by BATAN of Indonesia and JAERI of Japan and was jointly financed by UNDP/IAEA, Government of Japan and Government of Indonesia under UNDP/IAEA Regional Cooperative Agreement Project on Industrial Application of Isotopes and Radiation Technology. The facility is a water pool type and can accomodate 400 kCi Co-60. The Co-60 rack has two shapes, plate and cylindrical shapes. The plate shape source is used for natural rubber latex irradiation and the cylindrical one is used for other irradiation services. The vulcanization system consists of three major components : emulsification unit ( height : 650 mm, diameter 500 mm ), mixing unit ( height : 1900mm, diameter 1200 mm ) and vulcanization reactor ( height : 1800 mm, diameter 1300 mm ). The first two components are located outside shielded room while the third one-in irradiation room. The radiation vulcanization process is a much simpler energy saving process comparedto the conventional thermal process which has two vulcanization steps before and after dipping. The physical and mechanical properties of irradiated NR Latex are comparable to those of sulfur vulcanized, and depend on many factors such as irradiation dose, sensitizer content, dry rubber content and storage time.

  14. Anthelmintic activity of the latex of Ficus species.

    PubMed

    de Amorin, A; Borba, H R; Carauta, J P; Lopes, D; Kaplan, M A

    1999-03-01

    The latex of some species of Ficus (Moraceae) has been traditionally used as vermifuge in Central and South America. It has been accepted that anthelmintic activity is due to a proteolytic fraction called ficin. In the present study, the anthelmintic activity of the latex of Ficus insipida Willd. and Ficus carica L. has been investigated in NIH mice naturally infected with Syphacia obvelata, Aspiculuris tetraptera and Vampirolepis nana. The latex of F. insipida, administered by intragastric route in doses of 4 ml/kg/day during three consecutive days, were effective in the removal of 38.6% of the total number of S. obvelata, being inexpressive in the removal of A. tetraptera (8.4%) and segments of V. nana (6.3%). The latex of F. carica, administered in doses of 3 ml/kg/day, during three consecutive days, was effective in the removal of S. obvelata (41.7%) and it did not produce significant elimination of A. tetraptera (2.6%) and V. nana (8.3%). The observed high acute toxicity with hemorrhagic enteritis, in addition to a weak anthelmintic efficacy, do not recommend the use of these lattices in traditional medicine.

  15. 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.

  16. How To Refinish Wood Siding With Latex Paints

    Treesearch

    E. A. Mraz

    1976-01-01

    Every homeowner with painted wood siding and trim at some time faces the job of repainting. In this note a simple test is described to determine whether an old surface will form a satisfactory bond with latex paints, and suggestions are given on preparing the surface to achieve a satisfactory bond.

  17. 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.

  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. Production of Large-Particle-Size Monodisperse Latexes in Microgravity

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, M.

    1985-01-01

    A latex is a suspension of very tiny (micrometer-size) plastic spheres in water, stabilized by emulsifiers. The growth of billions of these tiny plastic spheres to sizes larger than can be grown on Earth is attempted while keeping all of them exactly the same size and perfectly spherical. Thus far on several of the Monodisperse Latex Reactor (MLR) flights, the latex spheres have been returned to Earth with standard deviations of better than 1.4%. In microgravity the absence of buoyancy effects has allowed growth of the balls up to 30 micrometers in diameter thus far. The MLR has now flown 5 times on the Shuttle. The MLR has now produced the first commercial space product; that is the first commercial material ever manufactured in space and marketed on Earth. Once it is demonstrated that these large-size-monodisperse latexes can be routinely produced in quantity and quality, they can be marketed for many types of scientific applications. They can be used in biomedical research for such things as drug carriers and tracers in the body, human and animal blood flow studies, membrane and pore-sizing in the body, and medical diagnostic tests.

  20. Metabolic routes affecting rubber biosynthesis in Hevea brasiliensis latex

    PubMed Central

    Chow, Keng-See; Mat-Isa, Mohd.-Noor; Bahari, Azlina; Ghazali, Ahmad-Kamal; Alias, Halimah; Mohd.-Zainuddin, Zainorlina; Hoh, Chee-Choong; Wan, Kiew-Lian

    2012-01-01

    The cytosolic mevalonate (MVA) pathway in Hevea brasiliensis latex is the conventionally accepted pathway which provides isopentenyl diphosphate (IPP) for cis-polyisoprene (rubber) biosynthesis. However, the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway may be an alternative source of IPP since its more recent discovery in plants. Quantitative RT-PCR (qRT-PCR) expression profiles of genes from both pathways in latex showed that subcellular compartmentalization of IPP for cis-polyisoprene synthesis is related to the degree of plastidic carotenoid synthesis. From this, the occurrence of two schemes of IPP partitioning and utilization within one species is proposed whereby the supply of IPP for cis-polyisoprene from the MEP pathway is related to carotenoid production in latex. Subsequently, a set of latex unique gene transcripts was sequenced and assembled and they were then mapped to IPP-requiring pathways. Up to eight such pathways, including cis-polyisoprene biosynthesis, were identified. Our findings on pre- and post-IPP metabolic routes form an important aspect of a pathway knowledge-driven approach to enhancing cis-polyisoprene biosynthesis in transgenic rubber trees. PMID:22162870

  1. 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.

  2. Effects on film structure on mechanical and adhesion properties of latex films

    SciTech Connect

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

    1995-12-31

    In order to investigate the effect of the particular structure of latex films on mechanical (stress-strain behavior) and adhesion (measured by peeling) properties, this work compares these characteristics for latex films and corresponding {open_quotes}solution films{close_quotes}. Solution films were obtained by dissolving the latex film in an appropriate solvent and forming a new film by evaporating the solvent. Four different systems were studied. It was shown that latex films have Young`s moduli systematically much higher than the corresponding solution films. This is due to the fact that the hydrophilic shells of the latex particles form a continuous phase in the latex film which increases the modulus thanks to polar interactions. However, adhesion energy for latex films is always smaller than for solution films. This is interpreted in terms of structure of the film-support interface and dissipative processes within the bulk of the films.

  3. Defense-related Proteins from Chelidonium majus L. as Important Components of its Latex.

    PubMed

    Nawrot, Robert

    2017-01-01

    The aim of this review is to cover most recent research on plant pathogenesis- and defenserelated proteins from latex-bearing medicinal plant Chelidonium majus (Papaveraceae) in the context of its importance for latex activity, function, pharmacological activities, and antiviral medicinal use. These results are compared with other latex-bearing plant species and recent research on proteins and chemical compounds contained in their latex. This is the first review, which clearly summarizes pathogenesisrelated (PR) protein families in latex-bearing plants pointing into their possible functions. The possible antiviral function of the latex by naming the abundant proteins present therein is also emphasized. Finally latex-borne defense system is hypothesized to constitute a novel type of preformed immediate defense response against viral, but also non-viral pathogens, and herbivores. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Temperature Response of Rhodamine B-Doped Latex Particles. From Solution to Single Particles.

    PubMed

    Soleilhac, Antonin; Girod, Marion; Dugourd, Philippe; Burdin, Béatrice; Parvole, Julien; Dugas, Pierre-Yves; Bayard, François; Lacôte, Emmanuel; Bourgeat-Lami, Elodie; Antoine, Rodolphe

    2016-04-26

    Nanoparticle-based temperature imaging is an emerging field of advanced applications. Herein, the sensitivity of the fluorescence of rhodamine B-doped latex nanoparticles toward temperature is described. Submicrometer size latex particles were prepared by a surfactant-free emulsion polymerization method that allowed a simple and inexpensive way to incorporate rhodamine B into the nanoparticles. Also, rhodamine B-coated latex nanoparticles dispersed in water were prepared in order to address the effect of the dye location in the nanoparticles on their temperature dependence. A better linearity of the temperature dependence emission of the rhodamine B-embedded latex particles, as compared to that of free rhodamine B dyes or rhodamine B-coated latex particles, is observed. Temperature-dependent fluorescence measurements by fluorescent confocal microscopy on individual rhodamine B-embedded latex particles were found similar to those obtained for fluorescent latex nanoparticles in solution, indicating that these nanoparticles could be good candidates to probe thermal processes as nanothermometers.

  5. Concrete blocks` adverse effects on indoor air and recommended solutions

    SciTech Connect

    Ruppersberger, J.S.

    1995-04-01

    Air infiltration through highly permeable concrete blocks can allow entry of various serious indoor air pollutants including radon. An easy approach to avoiding these pollutants is to select a less-air-permeable concrete block. Tests show that air permeability of concrete blocks can vary by a factor greater than 50 (0.63--35 standard L/min/m{sup 2} at 3 Pa). The surface texture of the blocks correlates well with air permeability; test results of smoother, closed-surface-texture blocks were usually less air-permeable. During construction, air infiltration can be minimized by capping walls and carefully sealing around openings for utilities or other penetrations. Structures with indoor air-quality problems due to soil-gas entry can be mitigated more effectively with less coating material if the blocks have a closed surface texture. All coatings evaluated--cementaceous block filler (which has the lowest applied cost and is more than 99.5% effective), surface bonding cement, water-based epoxy, polysulfide vinyl acrylic, and latex (three coats)--were highly effective (more than 98%) in reducing air permeability when adequately applied. Coating selection should be influenced by expected service life, considering surface condition and cost.

  6. Binding and measuring natural rubber latex proteins on glove powder.

    PubMed

    Tomazic-Jezic, Vesna J; Lucas, Anne D; Sanchez, Beatriz A

    2004-01-01

    Cornstarch used as a donning powder on natural rubber latex (NRL) gloves adsorbs NRL proteins. During glove use, powder-carried proteins can be aerosolized and can cause allergic reactions in NRL sensitized individuals. The amount of NRL proteins bound to glove powder and its relative relationship to the total amount of proteins on the glove has not been studied, due to the difficulty in measuring proteins on powder. Using the ELISA inhibition assay for NRL proteins [Standard test method for the immunological measurement of antigenic protein in natural rubber and its products. In: The Annual Book of ASTM Standards; ASTM: West Conshohocken, PA, 2000; ASTM D 64-0] we have investigated possible protocol modifications in order to include measurement of proteins bound to glove powder, as well as the water-extractable glove proteins. Possible interference of the starch itself was evaluated by adding clean cornstarch to the assay. No significant interference was observed with powder concentrations below 5 mg/mL. We analyzed 19 extracts of powdered surgical and examination gloves before and after removal of the particulate component. Comparison of NRL glove extracts with, and without, the cornstarch powder fraction indicated significant variations in the ratios of powder-bound protein and corresponding water-extractable protein. The ratios did not appear to correlate with either the total protein on the glove, the glove weight, or the total amount of powder on the glove. However, when virgin glove powders were exposed to NRL proteins, binding was proportional to the protein concentration in the suspension. Temperature in the range from 4 degrees C to 37 degrees C, did not affect binding intensity, while a higher pH resulted in a higher level of protein associated with, or bound to, the starch. The major differences in the propensity for NRL protein binding were observed among different glove powders. The data indicate that the amount of protein that binds to glove powder

  7. 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

  8. 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

  9. Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete.

    PubMed

    Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

    2016-03-07

    Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete.

  10. Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete

    PubMed Central

    Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

    2016-01-01

    Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete. PMID:28773298

  11. Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

    SciTech Connect

    Button, J.W.; Prapnnachari, S.

    1991-01-01

    Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials including aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.

  12. 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.

  13. A discussion of natural rubber latex allergy with special reference to children: clinical considerations.

    PubMed

    Eustachio, Nettis; Cristina, Colanardi Maria; Antonio, Ferrannini; Alfredo, Tursi

    2003-09-01

    Latex allergy is an increasingly common condition, because the use of latex products is widespread. Three types of reactions can occur in persons using natural latex rubber products: 1) Irritant contact dermatitis, 2) Allergic contact dermatitis, 3) and Type I hypersensitivity. Children's subpopulations at particular risk include: atopics, individuals with spina bifida, or individuals who required frequent surgical instrumentations. An association between allergy to latex and allergy to various fruits and vegetables has been reported. Recently, an homology between latex allergens and mold allergens has been reported leading to postulate a possible existence of a "latex-mold syndrome". Diagnosis of allergy is based initially on history, skin prick test and search for specific serum IgE. Provocation tests may confirm the suspicion, although these are seldom performed on children because they are not easy to bear with. The most effective strategy to decrease the incidence of NRL (natural rubber latex) sensitization is avoidance; however, this is virtually impossible, given the large number of latex products we encounter since childhood. Studies of secondary prophylaxis among children demonstrate that notwithstanding recommendations, children could manifest yet adverse reactions to latex products and have detectable levels of anti latex IgE.

  14. 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

  15. 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

  16. Prenatal latex sensitization in patients with spina bifida: a pilot study.

    PubMed

    Boettcher, Michael; Goettler, Susanne; Eschenburg, Georg; Kracht, Thorben; Kunkel, Philip; Von der Wense, Axel; Reinshagen, Konrad

    2014-03-01

    Patients with spina bifida are particularly vulnerable to developing immunoglobulin E (IgE)-mediated latex sensitization. Even though many risk factors leading to latex allergy in these patients have been described, it is still unclear whether the increased prevalence of latex sensitization is disease associated or due to the procedures used to treat spina bifida. The aim of this study was to assess prenatal latex sensitization in patients with spina bifida by examining IgE levels in umbilical cord blood. Patients with spina bifida and matched healthy infants were recruited from the University Medical Center Hamburg-Eppendorf and Children's Hospital Altona. Latex-specific and total IgE were assessed in umbilical cord blood using ImmunoCAP testing to evaluate the degree of prenatal latex sensitization. Twenty-two subjects, 10 with spina bifida and 12 healthy individuals, were included. Subjects were selected after matching for sex, gestational age, weight, parental allergy profile, number of prenatal examinations, and utilization of latex tools during pregnancy (propensity score estimates, p = 0.36). In patients with spina bifida, latex-specific and total IgE levels were significantly higher than those in healthy individuals (p = 0.001). After normalization to total IgE, latex-specific IgE levels were higher, yet not significantly increased (p = 0.085). Perinatally, there is a significant augmentation of total and latex-specific IgE in patients with spina bifida. After correcting for total IgE, latex-specific IgE was increased, yet not significantly higher than in matched, healthy controls. This pilot study gives novel insights in the immunological reactions related to spina bifida. The increased latex-specific IgE levels could possibly be associated with the occurrence of a latex allergy in the future.

  17. Comparison of the substrate effect on VOC emissions from water based varnish and latex paint.

    PubMed

    Silva, Gabriela V; Vasconcelos, M Teresa S D; Santos, Armando M; Fernandes, Eduardo O

    2003-01-01

    The building materials are recognised to be major contributors to indoor air contamination by volatile organic compounds (VOCs). The improvement of the quality of the environment within buildings is a topic of increasing research and public interest. Legislation in preparation by the European Commission may induce, in the near future, European Union Member States to solicit the industries of paints, varnishes and flooring materials for taking measures, in order to reduce the VOC emissions resulting from the use of their products. Therefore, product characterisation and information about the influence of environmental parameters on the VOC emissions are fundamental for providing the basic scientific information required to allow architects, engineers, builders, and building owners to provide a healthy environment for building occupants. On the other hand, the producers of coating building materials require this information to introduce technological alterations, when necessary, in order to improve the ecological quality of their products, and to make them more competitive. Studies of VOC emissions from wet materials, like paints and varnishes, have usually been conducted after applying the material on inert substrates, due to its non-adsorption and non-porosity properties. However, in real indoor environments, these materials are applied on substrates of a different nature. One aim of this work was to study, for the first time, the VOC emissions from a latex paint applied on concrete. The influence of the substrate (uncoated cork parquet, eucalyptus parquet without finishing and pine parquet with finishing) on the emissions of VOC from a water-based varnish was also studied. For comparison purposes, polyester film (an inert substrate) was used for both wet materials. The specific emission rates of the major VOCs were monitored for the first 72 h of material exposure in the atmosphere of a standardized test chamber. The air samples were collected on Tenax TA and

  18. 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.

  19. Structural Materials: 95. Concrete

    SciTech Connect

    Naus, Dan J

    2012-01-01

    Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

  20. 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.

  1. Film formation and mechanical behavior of polymer latexes

    SciTech Connect

    Gauthier, C.; Sindt, O.; Perez, J.

    1995-12-31

    The purpose of this lecture is to review the present state of the art in the field of film formation in relation with the mechanical behavior of polymer films. After a review of the theoretical approaches concerning film forming process, we show the influence of some experimental parameters (temperature, hygrometry {hor_ellipsis}) in the case of a core-shell latex obtained from polystyrene/Poly (Styrene co. butyl acrylate). Then, the mechanical behavior of polymer films is considered. The improvement of the mechanical strength of latex films during the last stage of film formation (i.e., gradual coalescence) is illustrated. Further analysis of the molecular process yielding mechanical behavior allows us to show how the comparison between prediction and experimental data can provide information on morphological changes, on the stability of this one, or on the formation of an interphase between constituting phases.

  2. Distribution of surfactants in latex films: a Rutherford Backscattering study.

    PubMed

    Lee, Wai Peng; Gundabala, Venkata R; Akpa, Belinda S; Johns, Michael L; Jeynes, Chris; Routh, Alexander F

    2006-06-06

    Uneven distribution of surfactant in dried latex films can affect the final film properties such as its water-resistance, gloss, and adhesiveness. Therefore, it is important to understand the driving force for surfactant transport during drying. In this paper, the accumulation of surfactant on the surface of poly(styrene-co-butyl acrylate) latex is studied using Rutherford Backscattering (RBS) and compared with results from a model that is based on the diffusive transport of particles and surfactant. Experimentally, a 30-50 nm thick surface layer, rich in surfactant, is seen and the concentration in the bulk of the film, obtained from RBS, agrees, at least qualitatively, with the model predictions for two of the surfactants tested.

  3. Reinforcement of polymeric latexes by in situ polymerization.

    PubMed

    Vargas, Andres F; Brostow, Witold; Lobland, Haley E Hagg; López, Betty L; Olea-Mejia, Oscar

    2009-11-01

    Two silicas with different particle sizes have been synthesized by the Stöber method. The particles have been functionalized with methacryloyl groups. In situ emulsion polymerization of butyl acrylate and methyl methacrylate in the presence of functionalized silica particles was performed. The ratio of butyl acrylate to methyl methacrylate was varied in order to optimize the composition for improvement of tribological and thermophysical properties. The silica particles morphology and functionalization have been determined respectively by scanning electronic microscopy and infrared spectroscopy. The composites were characterized also by thermogravimetric analysis, differential scanning calorimetry, microscratch testing and static light scattering. The latex reinforced with the smallest functionalized silica exhibits higher thermal stability than the non reinforced latex, along with lower penetration depth and higher residual depth in progressive load scratch testing. Thus, the resistance to penetration is increased while viscoelastic healing is hampered by silica particles.

  4. RVNRL a potential material in latex dipped products manufacturing

    NASA Astrophysics Data System (ADS)

    Zin, Wan Manshol bin W.; Mohid, Norjanah; Razali, Meor Yahaya

    1995-09-01

    Preparation of radiation vulcanised natural rubber latex (RVNRL) using n-butyl acrylate as the sensitiser had been upgraded from a small scale to a bigger scale of about 500 kilograms per batch. Improvement on the physical properties of its vulcanisátes was observed. The tensile strength was determined to be about 28 MPa and the elongation at break of about 1000%. Despite its low ammonia content, about 0.4%, there was no negative effect detected neither on its alkalinity nor its stability. Upon incineration the film vulcanisate gave an ash residue as low as 0.7%. The sulphur content in the form of sulphate and sulphide were 0.11 mg per litre and < 0.001 mg per litre respectively. These properties plus other advantages discussed elsewhere make RVNRL a potential material for natural rubber latex dipped products manufacturing to suit the current needs.

  5. Graphene-philic surfactants for nanocomposites in latex technology.

    PubMed

    Mohamed, Azmi; Ardyani, Tretya; Bakar, Suriani Abu; Brown, Paul; Hollamby, Martin; Sagisaka, Masanobu; Eastoe, Julian

    2016-04-01

    Graphene is the newest member of the carbon family, and has revolutionized materials science especially in the field of polymer nanocomposites. However, agglomeration and uniform dispersion remains an Achilles' heel (even an elephant in the room), hampering the optimization of this material for practical applications. Chemical functionalization of graphene can overcome these hurdles but is often rather disruptive to the extended pi-conjugation, altering the desired physical and electronic properties. Employing surfactants as stabilizing agents in latex technology circumvents the need for chemical modification allowing for the formation of nanocomposites with retained graphene properties. This article reviews the recent progress in the use of surfactants and polymers to prepare graphene/polymer nanocomposites via latex technology. Of special interest here are surfactant structure-performance relationships, as well as background on the roles surfactant-graphene interactions for promoting stabilization.

  6. Preparing PNNL Reports with LaTeX

    SciTech Connect

    Waichler, Scott R.

    2005-06-01

    LaTeX is a mature document preparation system that is the standard in many scientific and academic workplaces. It has been used extensively by scattered individuals and research groups within PNNL for years, but until now there have been no centralized or lab-focused resources to help authors and editors. PNNL authors and editors can produce correctly formatted PNNL or PNWD reports using the LaTeX document preparation system and the available template files. Please visit the PNNL-LaTeX Project (http://stidev.pnl.gov/resources/latex/, inside the PNNL firewall) for additional information and files. In LaTeX, document content is maintained separately from document structure for the most part. This means that the author can easily produce the same content in different formats and, more importantly, can focus on the content and write it in a plain text file that doesn't go awry, is easily transferable, and won't become obsolete due to software changes. LaTeX produces the finest print quality output; its typesetting is noticeably better than that of MS Word. This is particularly true for mathematics, tables, and other types of special text. Other benefits of LaTeX: easy handling of large numbers of figures and tables; automatic and error-free captioning, citation, cross-referencing, hyperlinking, and indexing; excellent published and online documentation; free or low-cost distributions for Windows/Linux/Unix/Mac OS X. This document serves two purposes: (1) it provides instructions to produce reports formatted to PNNL requirements using LaTeX, and (2) the document itself is in the form of a PNNL report, providing examples of many solved formatting challenges. Authors can use this document or its skeleton version (with formatting examples removed) as the starting point for their own reports. The pnnreport.cls class file and pnnl.bst bibliography style file contain the required formatting specifications for reports to the Department of Energy. Options are also provided for

  7. Ocular toxicity by latex of Calotropis procera (Sodom apple).

    PubMed

    Basak, Samar K; Bhaumik, Arup; Mohanta, Ayan; Singhal, Prashant

    2009-01-01

    We report the spectrum of ocular toxicity following accidental inoculation of latex of Calotropis procera (Sodom apple) in 29 eyes between January 2003 and December 2006. All patients presented with sudden painless dimness of vision with photophobia. Twenty-five (86%) patients had initial visual acuity of less than 20/60. All eyes had conjunctival congestion and mild to severe corneal edema with Descemet's folds. Three (10%) eyes had an epithelial defect, nine (31%) had iridocyclitis, and seven (24%) had associated secondary glaucoma. After treatment with topical corticosteroids, antiglaucoma agents, cycloplegics, hypertonic saline and tears supplements, 27 (93%) eyes recovered completely within 3-14 days. After three months, 17 (74%) out of 23 eyes showed a significant low endothelial cell count compared to the normal fellow eye ( P 0.001). The latex of Calotropis procera causes significant ocular morbidity which may be preventable by simple health education. The long-term effect on corneal endothelium has to be studied further.

  8. Cataract surgery for natural rubber latex allergic patients.

    PubMed

    Cheung, D; Gillow, T

    2003-03-01

    The prevalence of reactions against natural rubber latex (NRL) is thought to be increasing in both the general public and healthcare workers. These can vary from mild benign skin reactions to bronchospasm, anaphylactic shock, and death. Difficulties exist for ophthalmic departments wishing to establish protocols in providing 'latex-free environments' for patients undergoing cataract surgery. Currently no legislation exists regarding the labelling of NRL-containing products in the United Kingdom with information on a product's NRL content provided by the manufacturer on a voluntary basis only. It is hoped this review article will act as a basic guide in the management of NRL-sensitive patients undergoing cataract surgery in the United Kingdom.

  9. 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.

  10. Difference in latex properties by the preparation methods of radiation and chemical initiators

    NASA Astrophysics Data System (ADS)

    Egusa, S.; Makuuchi, K.

    Copolymer latexes of n-butyl methacrylate (nBMA), 2-hydroxyethyl methacrylate (HEMA), and acrylic acid were prepared with 60 Co γ-rays and the redox initiator system of {(NH 4) 2S 2O 8}/{NaHSO 3} at polymerization temperatures of 20 to 80°C. The resulting latexes were characterized with regard to the fundamental properties such as viscosity, particle size, distribution of acid groups, and electrolyte stability. The characterization revealed essential differences in these properties between the radiation- and chemically-prepared latexes. The differences are interpreted by the presence of strong acid groups of sulfate and sulfonate in the chemically-prepared latex and by the absence of such strong acid groups in the radiation-prepared latex. The absence of strong acid groups was found to make the latex more resistant to the hydrolysis of ester groups of nBMA and HEMA during and after the polymerization.

  11. Synthesis of polyacrylate core-shell structure latex by radiation techniques

    NASA Astrophysics Data System (ADS)

    Minghong, Wu; Weiping, Shen; Zueteh, Ma

    1993-07-01

    A series of poly(butyl acrylate-co-methyl methacrylate)/poly (ethyl acrylate-co-acrylic acid) interpenetrating polymer network (IPN) was synthesized in latex form by emulsion polymerization. The multiphase morphology of the latex particles was studied after two-stage polymerization by using transimission electron microscope (TEM), the result indicated that the morphology of the particles comprises gradient shell structure, cellular structure and core-shell structure. The change of morphology might stem from emulsion polymerization by radiation initiation or chemical initiation and the weight composition of poly(EA-co-MMA) seed latex which formed the core. By radiation techniques, we successfully synthesized poly( BA-co-MMA)/poly(EA-co-AA) latex of core-shell structure having (42-8)/(46-4) weight compositions. The PA core-shell structure latex applied to textile as a water proofing coating showed higher water-pressure and easier handling than that with PA homogeneous phase structure latex.

  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. Low prevalence of allergy to cockroach and latex in asthmatic patients in Eskisehir (Anatolia), Turkey.

    PubMed

    Harmanci, E; Metintas, M; Alatas, F; Erginel, S; Mutlu, S

    2000-01-01

    Allergy to cockroach and latex are said to be causes of asthma particularly in some groups. We studied allergy to cockroach and latex in asthmatic patients from Eskisehir (Anatolia), Turkey in order to determine whether these allergens play an important role in the Anatolian region. A total of 216 asthmatic patients (mean age 43.7+/-11.0 years) were skin tested with common aeroallergens, Blatella germanica and latex. Sixty-three patients were allergic (29.1%) and 153 were nonallergic (70.8%) according to skin test results. Sensitization to pollens (57%) and mites (55.5%) was most common among allergic patients. We found a low sensitization to cockroach (4.7%) and latex (1.4%). We suggested that cockroach sensitization plays a small role in sensitization in our geographic area and that latex sensitization is low in allergic asthmatic patients who were referred for reasons other than latex-related symptoms.

  14. [Retrospective study on the prevalence of latex allergic pathology in health personnel].

    PubMed

    Fenga, C; Russo, O; Cacciola, A; Guarneri, F; Loreto, C; Trimarchi, G

    2001-01-01

    To evaluate the prevalence of latex sensitisation and latex-related symptoms, we performed a study on 837 hospital employees. All subjects were asked for medical and occupational history, and underwent Skin Prick Test (SPT) with latex and other airborne allergens. The results showed a prevalence of latex sensitisation of 6.1% and a prevalence of symptoms of 5.26%. The most frequent symptoms were oculorhinitis, dermatitis and asthma. The one-year retrospective evaluation showed, in a group of 767 hospital attendants selected by the whole population, an incidence of sensitisation of 0.26%; no new cases of latex-related symptomatology were observed. The improvement of symptoms was due to the reduction of the exposure to latex gloves. The results of the study confirm the importance of prevention strategies.

  15. A simple optical sensor for the measurement of dry rubber content in natural rubber latex

    NASA Astrophysics Data System (ADS)

    George, Nibu A.; Peethan, Akhila; Vijayan, Midhula

    2013-12-01

    In this article, we report a new method to measure dry rubber content (DRC) in natural latex using a light scattering principle. Latex collected from the field, without diluting or any other chemical processing, can be directly used in this technique to measure its DRC. A laser beam transmitted through a thin column of latex is imaged using a digital camera and the image is processed to calculate the strength of scattering. We have observed a linear relationship between the DRC of the latex and the full width at half of the maximum of the laser beam intensity profile. The method requires only a very small quantity (about 0.5 g) of latex and the measurement is very fast, taking only a few minutes. Although we have demonstrated the described method for latex characterisation, this method can be extended for turbidity/particle concentration measurement of any heavily scattering liquids.

  16. Extractable proteins from irradiated field natural rubber latex

    NASA Astrophysics Data System (ADS)

    Rogero, Sizue O.; Lugão, Ademar B.; Yoshii, Fumio; Makuuchi, Keizo

    2003-06-01

    In this study field natural rubber latex was irradiated with different doses near a 60Co gamma source to reduce the water-soluble protein content in the final product. The protein content of the films obtained by casting method was extracted with phosphate buffer solution, pH 7 and was measured using Micro BCA Protein Assay kit. Also was measured protein in the serum samples of field NRL. The concentration of extractable proteins increased with increasing radiation dose.

  17. Ultrasound enhanced detection of individual meningococcal serogroups by latex immunoassay

    PubMed Central

    Sobanski, M A; Vince, R; Biagini, G A; Cousins, C; Guiver, M; Gray, S J; Kaczmarski, E B; Coakley, W T

    2002-01-01

    Aims: To examine A, C, Y, and W135 Neisseria meningitidis serogroup characterisation by ultrasonic standing wave enhanced latex agglutination tests (USELATs) of clinical samples. In addition, to determine USELAT enhancement of detection sensitivity for the individual antigens compared with conventional card latex agglutination tests (LATs). Methods: Wellcogen (Abbott Murex), Slidex meningite kit 5 (bioMerieux), and Pastorex (Sanofi) kits and beads coated in house with antibodies to Y and to W135 alone were tested. Positive control antigens consisted of A and C polysaccharide preparations and the Pastorex Y/W135 kit sample. The limiting concentrations of antigen detection were determined by USELAT and by LAT. Thirty five clinical samples (plasma), previously characterised by the polymerase chain reaction (PCR) and culture, were tested by USELAT and, when sample volume allowed, by LAT. Results: USELAT enhancement of control antigen detection ranged from 16 to 128 fold for the different latex systems. Enhancements for the different control antigens were comparable between kits. USELAT tests of clinical (A/C/Y/W135) samples (n = 15) with the Wellcogen (A/C/Y/W135) and Slidex meningite (A/C/Y/W135) kits showed comparable specificities. A set (n = 22) of Y and W135 samples gave 18, 19, and 17 positive results for Wellcogen (A/C/Y/W135), Pastorex (A/C/Y/W135), and in house beads (Y/W135), respectively. Positive USELAT PCR and culture results were concordant. A typical sensitivity for the commercial kits was 80% (Wellcogen). Conclusions: USELAT identified serogroups for 80% of samples, whereas LATs identified only 40%. The USELAT detection of the A, C, Y, and W135 antigen serogroups showed comparable enhancement for the kits tested. The commercial availability of latex beads coated with antibody to the Y and W135 serogroups would expedite their identification. PMID:11825922

  18. Enzymatic activities and protein profile of latex from Calotropis procera.

    PubMed

    Freitas, Cleverson Diniz T; Oliveira, Jefferson Soares; Miranda, Maria Raquel A; Macedo, Nívea Maria R; Sales, Maurício Pereira; Villas-Boas, Laurival A; Ramos, Márcio Viana

    2007-01-01

    The laticifer fluid of Calotropis procera is rich in proteins and there is evidence that they are involved in the pharmacological properties of the latex. However, not much is known about how the latex-containing proteins are produced or their functions. In this study, laticifer proteins of C. procera were pooled and examined by 1D and 2D electrophoresis, masses spectrometry (MALDI-TOF) and characterized in respect of proteolytic activity and oxidative enzymes. Soluble laticifer proteins were predominantly composed of basic proteins (PI>6.0) with molecular masses varying between 5 and 95 kDa. Proteins with a molecular mass of approximately 26,000 Da were more evident. Strong anti-oxidative activity of superoxide dismutase (EC 1.15.1.1) (1007.74+/-91.89 Ug(-1)DM) and, to a lesser extent ascorbate peroxidase (EC 1.11.1.1) (0.117(d)+/-0.013 microMol H(2)O(2)g(-1)min(-1)), were detected. However, catalase (EC 1.11.1.6) was absent. The strong proteolytic activities of laticifer proteins from C. procera were shown to be shared by at least four distinct cysteine proteinases (EC 3.4.22.16) that were isolated by gel filtration chromatography. Serine and metaloproteinases were not detected and aspartic proteinase activities were barely visible. Chitinases (EC 3.2.1.14) were also isolated in a chitin column and their activities quantified. The presence of these enzymatic activities in latex from C. procera may confirm their involvement in resistance to phytopathogens and insects, mainly in its leaves where the latex circulates abundantly.

  19. Further insight into the latex metabolite profile of Ficus carica.

    PubMed

    Oliveira, Andreia P; Silva, Luís R; Andrade, Paula B; Valentão, Patrícia; Silva, Branca M; Gonçalves, Rui F; Pereira, José A; Guedes de Pinho, Paula

    2010-10-27

    Latex is a sticky emulsion that exudes upon damage from specialized canals from several plants. It contains several biologically active compounds, such as phytosterols, fatty acids, and amino acids. In plants, these compounds are involved in the interaction between plants, insects, and the environment. Despite its chemical, biological, and ecological importance, Ficus carica latex is still poorly studied. To improve the knowledge on the metabolite profile of this matrix, a targeted metabolite analysis was performed in a representative sample from F. carica latex. Seven phytosterols were determined by gas chromatography-ion trap mass spectrometry (GC-ITMS) and high-performance liquid chromatography coupled to diode array detection (HPLC-DAD), with β-sitosterol and lupeol being the compounds present in higher concentrations (ca. 54 and 14%, respectively). A total of 18 fatty acids were characterized by GC-ITMS, being essentially represented by saturated fatty acids (ca. 86.4% of total fatty acids). A total of 13 free amino acids were also identified by high-performance liquid chromatography coupled to ultraviolet-visible spectroscopy (HPLC/UV-vis), and cysteine and tyrosine were the major ones (ca. 38.7 and 31.4%, respectively). In humans, phytosterols and some polyunsaturated fatty acids, such as linoleic acid, are known for their anticarcinogenic properties. With regard to amino acids, some of them, such as glycine, are neurotransmitters. Our results reveal the presence of a wide diversity of compounds, from distinct classes, in F. carica latex, possessing various potential pharmacological activities; thus, its biological potential appears to be worth further exploring.

  20. Chitinase III in Euphorbia characias latex: Purification and characterization.

    PubMed

    Spanò, Delia; Pospiskova, Kristyna; Safarik, Ivo; Pisano, Maria Barbara; Pintus, Francesca; Floris, Giovanni; Medda, Rosaria

    2015-12-01

    This paper deals with the purification of a class III endochitinase from Euphorbia characias latex. Described purification method includes an effective novel separation step using magnetic chitin particles. Application of magnetic affinity adsorbent noticeably simplifies and shortens the purification procedure. This step and the subsequently DEAE-cellulose chromatography enable to obtain the chitinase in homogeneous form. One protein band is present on PAGE in non-denaturing conditions and SDS-PAGE profile reveals a unique protein band of 36.5 ± 2 kDa. The optimal chitinase activity is observed at 50 °C, pH 5.0. E. characias latex chitinase is able to hydrolyze colloidal chitin giving, as reaction products, N-acetyl-D-glucosamine, chitobiose and chitotriose. Moreover, we observed that calcium and magnesium ions enhance chitinase activity. Finally, we cloned the cDNA encoding the E. characias latex chitinase. The partial cDNA nucleotide sequence contains 762 bp, and the deduced amino acid sequence (254 amino acids) is homologous to the sequence of several plant class III endochitinases. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Cytotoxic cardenolides from the latex of Calotropis procera.

    PubMed

    Mohamed, Nadia H; Liu, Miaomiao; Abdel-Mageed, Wael M; Alwahibi, Lamya H; Dai, Huanqin; Ismail, Mady Ahmed; Badr, Gamal; Quinn, Ronald J; Liu, Xueting; Zhang, Lixin; Shoreit, Ahmed A M

    2015-10-15

    Three new cardenolides (3, 9 and 10), along with eight known ones, were isolated from the latex of Calotropis procera. The structural determination was accomplished by the 1D- and 2D-NMR spectra as well as HRESIMS analysis. The growth inhibitory activity of the latex and its sub-fractions as well as isolated compounds was evaluated against human A549 and Hela cell lines. The results exhibited that latex had strong growth inhibitory activity with IC50s of (3.37 μM, A-549) and (6.45 μM, Hela). Among the four extracts (hexane, chloroform, ethyl acetate and aqueous), chloroform extract displayed the highest potential cytotoxic activity, with IC50s of (0.985 μM, A-549) and (1.471 μM, Hela). All the isolated compounds displayed various degrees of cytotoxic activity and the highest activity was observed by calactin (1) with IC50s values of (0.036 μM, A-549) and (0.083 μM, Hela). None of these isolated compounds exhibited good antimicrobial activity evaluated by determination of their MICs using the broth microdilution method against various infectious pathogens. The structure-activity relationships for cytotoxic activity were also discussed.

  2. Therapeutic effects of fig tree latex on bovine papillomatosis.

    PubMed

    Hemmatzadeh, F; Fatemi, A; Amini, F

    2003-12-01

    The effects of fig tree latex in treating teat papillomatosis in cow in comparison with salicylic acid were evaluated. For this purpose, 12 cows of 1-3 years of age (average 2.25) affected by teat papillomatosis were divided into three groups. In group A, four cows were treated by fig tree (Ficus carica) latex; in group B, four cows were treated with 10% salicylic acid solution and in group C, four cows were kept as control animals receiving no treatment. Animals in each treatment group received their treatment once every 5 days. In groups A and B, de-epithelialization and shrinking of the warts began from the fifth day of treatment and all the warts disappeared within 30 days. However, in the control group no changes in the number of warts were observed until day 15 but thereafter a number of warts disappeared spontaneously in some of the animals. Both salicylic acid and fig tree latex were evaluated as having similar therapeutic effects in treating teat papillomatosis in cow.

  3. Biocompatibility of natural latex implanted into dental alveolus of rats.

    PubMed

    Balabanian, Cláudia A C A; Coutinho-Netto, Joaquim; Lamano-Carvalho, Teresa L; Lacerda, Suzie A; Brentegani, Luiz G

    2006-12-01

    The present study investigated the biocompatibility of a biopolymer based on vegetable latex extracted from the Hevea brasiliensis rubber tree, implanted into the bony alveolar cavity after dental extraction in rats. A granule of latex (area = 0.25 +/- 0.04 mm(2)) was implanted inside the alveolus immediately after extraction of the upper right incisor, and the animals were sacrificed 7, 21 and 42 days after the procedure. The hemi-maxillas were decalcified and processed for embedding in paraffin to obtain semi-serial longitudinal sections 5 mum thick, and then stained with hematoxylin-eosin. The latex granule was observed in the cervical third of the alveolus without any foreign body reaction, or persistence of the initial acute inflammatory reaction. Bone repair in the areas adjacent to the material was quantified, and a decrease was noted in the thickness of the fibrous capsule surrounding the implants from 92.8 +/- 9.3 microm on day 7 to 9.4 +/- 1.8 microm on day 42 (ANOVA, P = 0.01). The quantitative data confirmed acceleration of bone formation (statistically significant at 5%) in parallel with a decrease of connective tissue in the areas around the implants. These results show that the tested material is biologically compatible, and progressively integrated into the alveolar bone, simultaneously accelerating bone formation and playing an important role in the healing process.

  4. Effect of chitosan content on gel content of epoxized natural rubber grafted with chitosan in latex form.

    PubMed

    Riyajan, Sa-Ad; Sukhlaaied, Wattana

    2013-04-01

    The epoxidized natural rubber (ENR) latex-g-chitosan (ENR-g-chitosan) was prepared in latex form using potassium persulphate as an initiator. Firstly, the reduction in molecular weight of chitosan was subjected to the addition of K2S2O8 at 70 °C for 15 min. The structure of the modified chitosan was characterized by ATR-FTIR. Secondarily, the influence of chitosan contents, reaction time, and temperature and K2S2O8 concentrations on the gel content of the modified ENR was investigated. The chemical structure of the ENR-g-chitosan was confirmed by (1)H-NMR and ATR-FTIR. The ether linkage of the ENR-g-chitosan was conformed at 1154 an 1089 cm(-1) by ATR-FTIR and 3.60 ppm by (1)H-NMR. The gel content of ENR-g-chitosan at 5% chitosan showed the highest value compared with other samples. But when chitosan increased from 5% to 10% or 20%, the gel content of ENR-g-chitosan dramatically decreased. The ENR-g-chitosan showed good thermal resistance due to incorporation of chitosan. The morphology of ENR-g-chitosan particle showed the core-shell structure observed by TEM. The optimum condition of grafting ENR with chitosan was found at 65°C for 3h of reaction time, ratio of ENR/chitosan at 9:1.

  5. Micromechanics of Concrete.

    DTIC Science & Technology

    1988-01-25

    reflects the dispersion of the coarse aggregates on the mesoscale. Specifically, the experimental measure- ments indicate ( Mindess and Young 1981, Zaitsev...Mecanique des Materiaux Solides, Dunod, Paris. Mindess , S. and J. Young (1981), Concrete, Prentice-Hall Inc., Englewood Cliffs, NJ. Mura, T. (1982

  6. 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.

  7. 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.

  8. 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}).

  9. Concrete Forms; Carpentry: 901890.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    The course outline is designed to provide instruction in planning, laying out, and building various type forms for concrete. The course contains seven blocks of study totaling 135 hours in length. The student will be expected to have mastered basic construction skills and basic mathematics. Upon completing the course, the student will have an…

  10. Forterra Concrete Products, Inc.

    EPA Pesticide Factsheets

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Forterra Concrete Products, Inc., a business located at 511 E. John Carpenter Freeway, Irving, TX, 75062, for alleged violations at its facility located at 23600 W. 40th St

  11. Control of Musca domestica third instar larvae by the latex of Calotropis procera (Family: Asclepiadaceae).

    PubMed

    Morsy, T A; Rahem, M A; Allam, K A

    2001-04-01

    Calotropis procera (Family: Asclepiadaceae) is known to contain alkaloids, steroids and resinous substance. Different concentrations of its latex were topically applied to the 3rd stage larvae of Musca domestica. A dose of 3 ul (5% of the latex) killed and partially digested the larvae in three hours. The effect of this latex is most probably enzymatic in nature. No doubt, the shift to plant extracts in controlling insect-vectors or pests in general, pave the way to a health environment.

  12. 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

  13. Characterization of cross-reactive bell pepper allergens involved in the latex-fruit syndrome.

    PubMed

    Wagner, S; Radauer, C; Hafner, C; Fuchs, H; Jensen-Jarolim, E; Wüthrich, B; Scheiner, O; Breiteneder, H

    2004-11-01

    Between 30% and 50% of individuals who are allergic to latex products are also allergic to specific plant foods, a fact that is well documented as the latex-fruit syndrome. Simultaneous sensitization to latex and bell pepper has been previously reported. Although bell pepper fruits are frequently consumed raw, cooked or as a spice, little is known about the cross-reactive allergens. In this study we wished to identify bell pepper allergens involved in the latex-fruit syndrome. Sera of four patients who displayed clinical symptoms to latex and bell pepper were used in immunoblot studies on protein extracts of three different cultivars of fresh bell pepper and fresh Hevea latex. Cross-reactive allergens were identified by inhibition experiments using recombinant Hev b 8 (latex profilin), and natural Hev b 2 (latex beta-1,3-glucanase) in addition to the protein extracts. A novel cross-reactive IgE-reactive 30 kDa protein was subjected to sequence analysis. Three patients displayed IgE to profilins from bell pepper fruits and latex. Two patients possessed IgE to Hev b 2, a latex beta-1,3-glucanase, and a homologous protein in bell pepper. One patient possessed IgE reactive with a protein of 30 kDa identified by N-terminal sequencing as an l-ascorbate peroxidase and another patient to a protein of 38 kDa. Additionally, IgE binding proteins in two higher molecular weight ranges showed cross-reactive capacities. Our findings show on the molecular level that bell pepper is part of the latex-fruit syndrome. For the first time we have identified the major latex allergen Hev b 2, a beta-1,3-glucanase, and the bell pepper l-ascorbate peroxidase as cross-reactive allergens. We were also able to show that profilins are responsible for some of the IgE cross-reactivity.

  14. 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.

  15. Physiological changes and molluscicidal effects of crude latex and Milin on Biomphalaria glabrata.

    PubMed

    Yadav, Subhash C; Jagannadham, M V

    2008-04-01

    Euphorbian latex is commonly used as molluscicides and the Euphorbia milii latex was reported as most powerful molluscicidal agents. The physiological and lethal effects of the latex components of Euphorbia milii, on the intermediate host Biomphalaria spp., of the human liver parasite Schistosoma mansoni were described in this study. The standard methodologies for testing plant derived molluscicides formulated by World Health Organisation (WHO) were followed with some modifications. The young specimen of fresh water snails showed altered physiological and physical response towards latex components. The working concentration of non-proteinaceous fraction (up to 0.1%) of the latex reduced the active physiological behaviour but was non-lethal to young specimen of snails. However, proteinaceous fractions (0.1mg/l) of the latex were found lethal to snail population, and lethality was enhanced with small amount of the non-proteinaceous fraction (0.01%) of the latex. Milin, a serine protease(up to 0.1mg/l), isolated from the latex of Euphorbia milii significantly reduced the growth and feeding activity but was not lethal to young specimen of snails. With an addition of 0.01% of non-proteinaceous fractions to Milin, lethality result was similar to that of crude latex. Milin is likely to be responsible for alteration of normal physiological functions and lethality of snails, thus it may be used as a molluscicide to control transmission of the endemic disease schistosomiasis.

  16. 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.

  17. Minimizing latex exposure and allergy. How to avoid or reduce sensitization in the healthcare setting.

    PubMed

    Muller, Barbara A

    2003-04-01

    Healthcare professionals with long-term exposure to natural rubber latex products and patients who undergo multiple operations are at high risk for latex allergy. The clinical spectrum of this allergy ranges from self-limited contact urticaria to involvement of multiple organ systems in anaphylaxis. In this article, Dr Muller explores the roots of the latex allergy epidemic and offers insight into the manufacturing process of latex gloves. She also presents a clinical approach to prevent or ameliorate sensitization and manage allergic symptoms.

  18. Natural rubber latex hypersensitivity with skin prick test in operating room personnel.

    PubMed

    Nabavizadeh, Seyed Hessamedin; Anushiravani, Amir; Amin, Reza

    2009-12-01

    Hypersensitivity reactions to natural rubber latex have increased recently, especially among people with high exposure to latex allergens. Hypersensitivity reactions to latex are related to many conditions like occupational asthma. Our study was performed to determine the prevalence of hypersensitivity to natural rubber latex and potential food cross reactions in operation room personnel in Shiraz hospitals. In this cross-sectional, descriptive study, 580 operation room personnel filled out our questionnaire which included data about their personal history, symptoms of latex hypersensitivity, and other related allergies such as food hypersensitivity. An informed consent was obtained and skin prick tests were performed for natural rubber latex and potential food cross reactions (kiwi, banana, and potato). The obtained data were analyzed by SPSS and Chi-square test. 104 (17.9%) of the operating room personnel showed positive latex skin tests. We revealed a significant correlation between those with positive skin tests to latex with atopia, urthicaria, and food hypersensitivity. The prevalence did not vary by sex, age, education, surgical and non-surgical gloves users, or history of contact dermatitis. Latex hypersensitivity is common among operation room personnel. Evaluation of symptoms and prediction of future diseases necessitate screening tests in individuals at risk.

  19. Latex-specific proteins causing immediate-type cutaneous, nasal, bronchial, and systemic reactions.

    PubMed

    Jaeger, D; Kleinhans, D; Czuppon, A B; Baur, X

    1992-03-01

    We examined 70 patients reporting hypersensitivity reactions caused by latex articles. All patients suffered from urticaria, 36 from rhinitis, 31 from conjunctivitis, 22 from dyspnea, and 17 from systemic reactions, and four patients developed severe systemic complications during surgery. By means of inhalative challenge tests with powdered latex gloves, it could be demonstrated that the glove powder (cornstarch) obviously functions as a carrier for latex allergens, which then become airborne. Five of 18 patients undergoing such challenge tests demonstrated a significant increase of specific airway resistance; 17, acute rhinitis and/or conjunctivitis; and two, a systemic reaction. Sixty-two percent of the patients demonstrated specific IgE antibodies to natural latex, 58% to an irradiatively cross-linked, so-called, "hypoallergenic" latex preparation, and 46% to commercial-latex RAST disks (Pharmacia). No specific antibodies to cornstarch or a mixture of rubber chemicals were found. A good correlation (82%) exists between latex IgE RAST and latex skin prick test, as revealed in a subgroup of 45 subjects. By means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the latex allergen appears to be a mixture of proteins in a molecular weight range from 10 to 67 kd.

  20. [Recurrent effusion and granulomatous synovitis following total knee arthroplasty in association with latex allergy].

    PubMed

    Schuh, A; Thomas, P; Hönle, W; Schmickal, T

    2008-02-01

    An increasing number of articles report about allergic reactions in association with total knee arthroplasty. While most studies focus on allergic reactions to metallic components, few reports exist about reactions to bone cement or its ingredients. Allergy to natural rubber latex is a major occupational problem in the health care sector and a problem even in other occupations in which protective gloves are used. The allergic reaction to latex ranges from a minor skin rash to anaphylactic shock. Preventing exposure to latex is the key to managing and preventing this allergy. We report about a patient who developed recurrent effusion and granulomatous synovitis following total knee arthroplasty in association with latex allergy.

  1. 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

  2. Grand rounds: latex-induced occupational asthma in a surgical pathologist.

    PubMed

    Green-McKenzie, Judith; Hudes, Debra

    2005-07-01

    Latex allergy and sensitization have been an important problem facing health care workers. Providing a latex-safe environment is the intervention of choice. 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. 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. 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.

  3. 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.

  4. Latex agglutination test (LAT) for the diagnosis of typhoid fever.

    PubMed

    Sahni, Gopal Shankar

    2013-06-01

    The efficacy of latex agglutination test in the rapid diagnosis of typhoid fever was studied and the result compared with that of blood culture. This study included 80 children suffering from typhoid fever, among which 40 were confirmed by blood culture isolation and 40 had possible typhoid fever based on high Widal's titre (a four-fold rise in the titre of antibody to typhi "O" and "H" antigen was considered as a positive Widal's test result). Eighty children, 40 with febrile illness confirmed to be other than typhoid and 40 normal healthy children were used as negative controls. The various groups were: (i) Study group ie, group I had 40 children confirmed by culture isolation of Salmonella typhi(confirmed typhoid cases). (ii) Control groups ie, (a) group II with 40 febrile controls selected from paediatrics ward where cause other than S typhi has been established, (b) group III with 40 afebrile healthy controls that were siblings of the children admitted in paediatric ward for any reason with no history of fever and TAB vaccination in the last one year, and (c) group IV with 40 children with high Widal's titre in paired sera sample. Widal's test with paired sera with a one week interval between collections were done in all 40 patients. Latex aggtutination test which could detect 900 ng/ml of antigen as observed in checker board titration, was positive in all 40 children from group I who had positive blood culture and in 30 children from group IV who had culture negative and had high Widal's titre positive. Latex agglutination test was positive in 4 children in group II and none in group III. Using blood culture positive cases as true positive and children in groups II and III as true negative, the test had a sensitivity of 100% and specificity of 96%. Latex agglutination test was found to be significantly sensitive (100%) and specific (96%) and could detect 75% more cases in group IV (possible typhoid cases). Thus latex agglutination test can be used for rapid

  5. Strain rate effects for concrete and fiber-reinforced concrete subjected to impact loading. Final report, September 1982-August 1987

    SciTech Connect

    Shah, S.P.

    1987-10-01

    Despite it's extensive use, low tensile strength has been recognized as one of the major drawbacks of concrete. Although one has learned to avoid exposing concrete structures to adverse static tensile loads, these structures cannot be shielded from short duration dynamic tensile loads. Such loads originate from sources such as impact from missiles and projectiles, wind gusts, earthquakes and machine vibrations. In addition, modern computer-aided analysis and use of concrete for special structures such as reactor containment vessels, missile storage silos and fall-out shelters, has led to a growing interest in the cracking behavior of concrete. Experimental results indicate that the fracture strength and cracking behavior of concrete are affected by the rate of loading. To accurately predict the structural response under impact conditions, the knowledge of behavior of concrete at high rates of loading is essential. Using a two degree of freedom model guidelines were developed for designing an impact test setup, thus enabling one to conduct impact tests free of adverse inertial effects. Based on these guidelines, the author has developed an instrumented modified Charpy impact testing system. This experimental test setup was used to obtain basic information such as load-deflection relationship, fracture toughness, crack velocity (measured using Krak Gages), and load-strain history during an impact fracture event of plain concrete and SFRC.

  6. Protein characterisation of Brosimum gaudichaudii Trécul latex and study of nanostructured latex film formation.

    PubMed

    Barbosa, Eduardo F; Monge-Fuentes, Victoria; Oliveira, Natiela B; Tavares, Rebecca; Xavier, Mary-Ann E; Bemquerer, Marcelo Porto; Silva, Luciano P

    2014-12-01

    Brosimum gaudichaudii Tréc. (Moraceae) is a common Brazilian Cerrado plant known by its pharmaceutical industry relevance. The authors investigated the latex protein components and potential biotechnological applications. Some protein fragments had their sequences elucidated, presenting similarities to jacalin and Kunitz-type trypsin inhibitors. Amino acid residue modifications were found, such as glutamine N-terminal residue cyclisation into pyroglutamic acid residue, and mass differences corresponding to hexoses and N-acetylhexosamine presence. The latex was used to produce a nanoscale structured film, which presented an increased attraction and reduced adhesion behaviours. The film presented high homogeneity, as observed by low nanoroughness values, probably because of its intrinsic components, such as the jacalin-like protein that has known agglutination properties. The immobilised Kunitz-type trypsin inhibitor presence in the latex film allow us to point out to applications related to this inhibition, as in active food packaging, since these peptidase inhibitors are able to inhibit pests and microorganism proliferation.

  7. 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.

  8. Promoting the use of crumb rubber concrete in developing countries.

    PubMed

    Batayneh, Malek K; Marie, Iqbal; Asi, Ibrahim

    2008-11-01

    The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes.

  9. Latex Hypersensitivity among Allergic Egyptian Children: Relation to Parental/Self Reports

    PubMed Central

    El-Sayed, Zeinab A.; El-Sayed, Shereen S.; Zaki, Rehab M.; Salama, Mervat A.

    2014-01-01

    Background. Latex allergy is one of the major health concerns and allergic reactions to latex may be serious and fatal. Purpose. In this study, we sought to determine the frequency of latex hypersensitivity in a group of allergic Egyptian infants and children and its relation to the history provided by the patients or caregivers. Methods. We consecutively enrolled 400 patients with physician diagnosed allergic diseases. The study measurements included clinical evaluation for the site and duration of allergy, history suggestive of latex allergy, family history of allergy, and skin prick testing (SPT) using a commercial latex extract. Results. The study revealed that 16/400 (4%) patients had positive SPT; 11 of them only had positive history of sensitivity to latex. Positive latex SPT was reported in 3.4% (11/326) of patients with bronchial asthma, 5.9% (7/118) of patients with skin allergy, and 4.5% (2/44) of patients with allergic rhinitis. SPT was positive in 7.4% (4/54) of patients with concomitant respiratory and skin allergy. Latex SPT was more specific than sensitive (97.69% and 77.77%, resp.) with a negative predictive value of 99.47%. Conclusion. Although underrecognized, latex is an important allergen in the pediatric age group with a sensitization frequency of 4% among allergic children. It was observed to be especially associated with multiple allergic diseases coexisting in the same patient. Pediatric allergologists should educate their patients on latex allergy and encourage the use of latex-free products. PMID:25505988

  10. Role of cross-allergies to latex in clinical routine of anesthesia.

    PubMed

    Haeberle, Helene A; Lupic, Daniela; Midoro-Horiuti, Terumi; Kiefer, Ralph T; Schroeder, Torsten H; Unertl, Klaus; Dieterich, Hans Juergen

    2003-11-01

    To determine the applicability and reliability of a screening questionnaire to detect patients at high-risk of latex allergy; to assess the importance of other allergies such as profilin allergies (pollinosis) for presence of latex sensitization; and to determine the clinical effectiveness of preemptive avoidance of latex exposure in high-risk patients. Prospective, clinical trial. Operative theater of a university hospital. 95 adult patients. Patients were preoperatively screened and classified for present latex allergy (high-risk and low-risk group) according to a specially designed screening questionnaire. Anesthesia and surgery in the high-risk group were performed strictly avoiding latex-containing materials. The low-risk group (other allergies including pollinosis) received routine treatment, without latex-avoidance. Effects of latex avoidance or exposure were evaluated by measuring specific IgE titers perioperatively. According to the questionnaire, 45 patients at high risk were defined. Validity of classification of high-risk patients is supported by significantly higher total IgE and latex and grass profilin specific IgE compared to the low-risk group. There were no significant differences in other profilin-specific IgEs. In one case of severe anaphylactic reaction a drop of latex-specific IgE during surgery could be observed. The questionnaire allowed the identification of most patients at high risk for latex allergy. In isolated pollinosis no changes in any specific IgE levels were detectable. Strict avoidance of perioperative latex exposure in high-risk patients increases safety during anesthesia and surgery.

  11. Latex Allergies: A Review of Recognition, Evaluation, Management, Prevention, Education, and Alternative Product Use

    PubMed Central

    Schroyer, Traci; Catalfano, Jennifer

    2003-01-01

    Objectives: To provide information about latex allergies; to determine how to recognize, evaluate, and manage emergencies related to latex allergies; and how to identify those at risk for latex allergies. Additionally, ways to prevent latex exposure, to educate health care workers and athletes about latex allergy, and to provide safe alternatives to latex are investigated. Data Sources: We searched MEDLINE and SPORT Discus for the years 1998–2002 using the key words latex, allergies, rubber, anaphylaxis, gloves, cross-reaction, IgE (immunoglobulin G) proteins, and radioallergosorbent test (RAST). Background: Latex, a sap from the rubber tree, is found in many products used in everyday life. Latex is composed of compounds that may cause an allergic reaction, whose severity can range from irritant dermatitis to type IV dermatitis to type I systemic reaction. Recognition of the signs and symptoms associated with these reactions by the health care professional may help to prevent a more severe reaction from occurring. Reactions can be complicated by contact with other substances, thus causing a cross-reaction. Some individuals are more at risk of latex allergies due to repetitive exposure to latex through their career paths, multiple surgeries, other allergies, or respiratory conditions. Management of an acute reaction involves removal of the irritant, cleansing of the affected area, monitoring vital signs for changes, and seeking additional medical assistance as warranted. Recommendations: Those at risk may be identified through a thorough medical history and allergy testing. Prevention techniques and guidelines are examined, with an emphasis on education at multiple levels. Product information for nonlatex equipment and supplies for the athletic training room is offered, with additional resource information provided. PMID:16558678

  12. Immunoadjuvant properties of glove cornstarch powder in latex-induced hypersensitivity.

    PubMed

    Barbara, J; Santais, M-C; Levy, D A; Ruff, F; Leynadier, F

    2003-01-01

    Cornstarch powder present in medical gloves plays an important role in latex-induced hypersensitivity as allergen carrier either, by the inhalation route, by skin contact or by direct contact with mucous membranes. Our objective was to test the hypothesis that cornstarch could act as an immunoadjuvant in immediate type-I latex-induced hypersensitivity. Guinea-pigs were sensitized by intraperitoneal route with two different antigens (latex proteins and ovalbumin) with or without cornstarch powder. Airway responsiveness after specific bronchial provocation was evaluated and specific IgG and IgG1 levels were determined by enzyme-linked immunosorbent assay (ELISA). Controls were treated with cornstarch powder or saline alone. Animals sensitized with latex proteins (n = 7 in each group) showed significant bronchoconstriction (P < 0.03) and higher anti-latex antibody levels than the controls (P < 0.005). Guinea-pigs sensitized with latex-contaminated cornstarch had higher levels of specific antibodies than those sensitized with latex alone (P < 0.05). Animals sensitized to latex mixed with cornstarch showed higher bronchospasm than those treated with latex alone (P < 0.003). Animals sensitized to ovalbumin mixed with cornstarch also showed higher antibody and bronchoconstriction levels (P < 0.05) than those immunized with ovalbumin alone but antibody titres were significantly lower than those of the animals treated with ovalbumin and Freund's complete adjuvant (P < 0.01; n = 5 in each group). Our findings show that cornstarch powder increases antigen-induced bronchoconstriction and antibody production. This role of immunoadjuvant is not antigen-specific. The cornstarch powder used as donning agent in latex gloves is an allergen carrier and it can enhance latex-induced hypersensitivity.

  13. Penetration of concrete targets

    SciTech Connect

    Forrestal, M.J.; Cargile, J.D.; Tzou, R.D.Y.

    1993-08-01

    We developed penetration equations for ogive-nosed projectiles that penetrated concrete targets after normal impact. Our penetration equations predict axial force on the projectile nose, rigid-body motion, and final penetration depth. For target constitutive models, we conducted triaxial material experiments to confining pressures of 600 MPa and curve-fit these data with a linear pressure-volumetric strain relation and with a linear Mohr-Coulomb, shear strength-pressure relation. To verify our penetration equations, we conducted eleven penetration experiments with 0.90 kg, 26.9-mm-diameter, ogive-nosed projectiles into 1.37-m-diameter concrete targets with unconfined compressive strengths between 32-40 MPa. Predictions from our penetration equation are compared with final penetration depth measurements for striking velocities between 280--800 m/s.

  14. Micro Environmental Concrete

    NASA Astrophysics Data System (ADS)

    Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

    Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

  15. 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.

  16. 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.

  17. 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.

  18. Mechanics of Concrete II

    DTIC Science & Technology

    1990-10-18

    diffusivity of undamaged concrete is a problem in itself since the diffusivity of the thin transition zones (at the aggregate- cement matrix interface...C3A anhydride remains in the cement after the hydration. Assuming that the amount of gypsum added to portland cement3 clinker is 4% of Mcm (Biczok 1972...enables establishment of rational relationships between the chemical composition of the hardened cement paste, morphology of the pore system, and defect

  19. Nondestructive Concrete Characterization System

    DTIC Science & Technology

    2013-05-20

    Park, NC 27709-2211 15. SUBJECT TERMS Ultrasonic Pulse Velocity (UPV), Impact-Echo, Ultrasonic Pulse-Echo, Ultrasonic Attenuation, STTR Report Aldo... ultrasonic testing in conjunction with the resonance frequency. All results were within the specified tolerance of ±1 ft. The compressive strength of the...concrete blocks was measured by measuring the P-wave and S-wave time of travel with the pitch-catch method of ultrasonic testing. All results were

  20. Tonsil concretions and tonsilloliths.

    PubMed

    Pruet, C W; Duplan, D A

    1987-05-01

    Although infrequently seen in many clinical practices, tonsillar concretions can be the source of both fetor oris and physical and social concern for the patient. Though stones rarely form in the tonsil or peritonsillar area, the findings of calcified objects or stones anywhere within the body has long been a subject of interest. The salient features of these entities and their relevance to clinical practice are discussed in this article.

  1. 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).

  2. 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.

  3. 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.

  4. How health care organizations can establish and conduct a program for a latex-safe environment.

    PubMed

    Brown, Robert H; Hamilton, Robert G; McAllister, Mary A

    2003-03-01

    The advent of universal precautions brought about a dramatic increase in the use of natural rubber latex gloves, and reports of rubber latex allergies began appearing in the literature. In 1997 the Johns Hopkins Hospital created the interdisciplinary Latex Task Force to address the issue of creating, implementing, and evaluating a latex-safe environment. When suitable alternatives were available, all medical products that contained latex were to be removed from the hospital and nonlatex alternatives substituted. Latex medical gloves, especially powdered latex examination gloves, which were used in all patient care areas, were replaced by vinyl gloves. Yet because of the ongoing concern about strike-through and the minimal level of acceptance of fit with the vinyl gloves, the search for alternatives to the vinyl gloves continued. The task force recommended switching to nitrile examination gloves throughout the hospital. To facilitate the transition to another examination glove, new educational pamphlets about the nitrile gloves were developed. The switch to nitrile examination gloves was successfully completed, but conversion to nonlatex surgical gloves was less successful, with costs being the overwhelming impediment. Monitoring of latex-containing products and ongoing evaluations of alternatives are crucial in ensuring patient and health care worker safety.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  6. 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 ...

  7. 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

  8. 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... Foam Subcategory § 428.110 Applicability; description of the latex foam subcategory. The provisions of... foam except for those discharges from textile plants subject to the provisions of part 410 of...

  9. 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.

  10. Banded cucumber beetle (Coleoptera: Chrysomelidae) resistance in romaine lettuce: understanding latex chemistry

    USDA-ARS?s Scientific Manuscript database

    Many plants subjected to herbivore damage exude latex, a rich source of biochemicals, which play important roles in host plant resistance. Our previous studies showed that fresh latex from Valmaine, a resistant cultivar of romaine lettuce Lactuca sativa L., applied to artificial diet is highly deter...

  11. Industrial-hygiene survey report of Dow Chemical USA SB (styrene butadiene) Latex Facility, Freeport, Texas

    SciTech Connect

    Fajen, J.M.; Krishnan, E.R.

    1986-03-01

    The purpose of the survey was to obtain information on the SB latex production process and assess the potential for occupational exposure to 1,3-butadiene at the SB latex facility. The information will be used in determining the suitability of including the plant in an in-depth survey.

  12. 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

  13. 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

  14. 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.

  15. 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.

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

    PubMed

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

    2015-01-01

    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. 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. 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. 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.

  17. Latex allergy symptoms among health care workers: results from a university health and safety surveillance system.

    PubMed

    Epling, Carol; Duncan, Jacqueline; Archibong, Emma; Østbye, Truls; Pompeii, Lisa A; Dement, John

    2011-01-01

    We sought to describe risk factors for latex glove allergy symptoms among health care workers by combining data from an active clinical surveillance program and a comprehensive occupational health surveillance system. A total of 4,584 employers completed a latex allergy questionnaire. Six percent (n = 276) of subjects reported symptoms consistent with latex allergy. Years of latex glove use was a significant risk factor for latex allergy symptoms even after controlling for the effects of atopy, gender, age, race, fruit, and other allergies. Nurses, medical or lab technicians, physician's assistants, other clinical professionals, and housekeepers had the highest prevalence of latex glove allergy symptoms. Forty subjects (0.87%) who were confirmed as having latex sensitization. Sensitizsation may have been underestimated due to use of specific IgE antibody, less sensitive than skin-prick testing, and tiered design leading to laboratory assessment on a subset of the cohort. This surveillance program identified risk factors for latex allergy symptoms. Our findings provide a basis for tailoring future prevention strategies.

  18. 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.

  19. 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.

  20. [Predisposition to latex allergy undetected on preoperative evaluation: a case report].

    PubMed

    Kimura, Yuriko; Okamura, Makoto; Harioka, Tokuya; Hara, Tadashi; Kamiya, Kiyoshi; Matsukawa, Takashi

    2013-12-01

    A 70-year-old man was scheduled to undergo laparoscopic total gastrectomy for stomach cancer. He had no history of atopy, fruit allergies, or frequent exposure to natural rubber. Preoperative latex-specific IgE antibodies were negative. Anesthesia was induced, and the surgery was started uneventfully. Soon after the surgeon had begun to manipulate the intestine, the blood pressure suddenly dropped to 27/21 mmHg. Facial flushing was also observed. Anaphylactic shock caused by latex was strongly suspected, and surgery was immediately halted. The surgical gloves were changed to latex-free ones, and adrenaline was administered. The blood pressure was gradually normalized within 30 min, and the facial flushing mostly disappeared. Postoperative laboratory examination revealed that serum tryptase had increased to 34.4 microg l-1, 40 minutes after the onset of anaphylaxis, and decreased to 19.4 microg l-1, 24 hours than later. Latex-specific IgE antibodies and a prick test with latex were both positive. Consequently, the diagnosis of latex-induced anaphylactic reaction was confirmed. Because even detailed questioning and examination does not always identify such a predisposition, avoiding contactwith latex products is more rational exhaustively checking every preoperative patient for latex allergy

  1. Prevalence of latex allergy in a population of patients diagnosed with myelomeningocele.

    PubMed

    Parisi, Claudio A S; Petriz, Natalia A; Busaniche, Julio N; Cortines, María C; Frangi, Fernando A; Portillo, Santiago A; de Badiola, Francisco I

    2016-02-01

    Latex allergy is one of the main reasons of anaphylaxis in the operating room. The prevalence of this condition is higher among patients with myelomeningocele. Epidemiological data obtained from Argentine patients is scarce. To estimate the prevalence of latex sensitivity and latex allergy in a population of patients with myelomeningocele and to describe associated risk factors. Descriptive, cross-sectional, observational study. Family and personal history of allergy, number of surgeries, history of symptoms caused by having been in contact with latex or cross-reactive foods, eosinophil count, measurement of total immunoglobulin E and specific immunoglobulin E levels by means of skin and serologic testing for latex, aeroallergens and cross-reactive fruit. Eighty-two patients diagnosed with myelomeningocele were assessed: 41 were males and their average age was 15.3 ± 7.66 years old. Out of all patients, two did not complete skin and serologic testing. Among the remaining 80 patients, 16 (19.51%) had latex allergy, 46 (57.5%) were not allergic, and 18 (22%) showed sensitivity but not allergy. Having undergone more than five surgeries was a risk factor associated with latex allergy (p= 0.035). No significant association was observed with the remaining outcome measures. According to this study, the prevalence of latex allergy in this population of patients is 19.51% and the most important risk factor for this condition is a history of having undergone more than five surgeries. Sociedad Argentina de Pediatría.

  2. 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 ...

  3. Molecular profile of sensitization in subjects with short occupational exposure to latex.

    PubMed

    Lamberti, Monica; Buonanno, Rosaria; Ritonnaro, Chiara; Giovane, Giancarlo; Crispino, Vincenzo; Feola, Antonia; Medici, Nicola; Sannolo, Nicola; Di Carlo, Angelina; Di Domenico, Marina

    2015-01-01

    We examined the prevalence of latex allergy in subjects with occupational exposure to latex allergens for less than 5 years, determining the disease spectrum in symptomatic workers. We identified the most frequent molecular allergens by Immuno- CAP (ICAP), correlating the findings with skin prick test (SPT) results. Seven hundred twenty-three healthcare students using latex gloves on a regular basis were invited to participate in a baseline questionnaire screening. An ICAP serum test was performed only when a possible latex allergy was indicated by the questionnaire. The total number of participants responding to the baseline survey was 619. Glove-related symptoms were indicated by 4% (N = 25) of the students. The most common symptom was contact dermatitis (N = 18, 72%). In 12 subjects, ICAP revealed a real sensitization to latex, with a recombinant latex allergen profile showing a high frequency for rHev b 6.01 specific immunoglobulin E (sIgE) (N = 9, 67%). In these individuals, skin symptoms were more prevalent than other types (88%). The combined positivity for rHev b 6.01, rHev 8 and rHev b 5 determined by ICAP identified 92% of latex-allergic subjects with short-term exposure to latex. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  4. The allergenic properties of fresh and preserved Hevea brasiliensis latex protein preparations

    PubMed Central

    KEKWICK, R; BHAMBRI, S; CHABANE, M H; AUTEGARDEN, J-E; LEVY, D A; LEYNADIER, F

    1996-01-01

    The allergenic properties of the proteins of two lyophilized fractions of fresh natural rubber latex obtained by ultracentrifugation, the C serum and the sedimented bottom or lutoid fraction, have been compared with those of the serum proteins of two samples of high ammonia latex (HAL), [A]HALS obtained from HAL stored for more than 1 year, and [M]HALS derived from HAL stored for 6 weeks before ultracentrifugation and lyophilization. The most potent source of allergenic polypeptides both for skin prick testing of latex-sensitive patients and for immunoblots of their blood serum was the lutoid fraction of fresh latex. Skin prick tests and immunoblots of patients' sera showed that the allergenicity of the ammoniated latex decreased during storage. Skin prick tests using fractions of [A]HALS, C serum and lutoid proteins obtained after passage through a Sephacryl S300 column showed that the components of all three preparations which eluted in the largest volumes were almost equally effective in provoking the largest number of responses. Immunoblots of the sera of 43 latex-sensitive individuals showed that the majority (66%) of sera of the adult allergic patients reacted with a polypeptide of 19 kD. No characteristic pattern of binding latex polypeptides could be recognized in the sera from patients who were also asthmatic or from those who had had an anaphylactic response to latex proteins. PMID:8625530

  5. 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

  6. 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.

  7. 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.

  8. Suicidal Smothering by Rubber Latex Gloves and Handkerchief.

    PubMed

    Viero, Alessia; Cecchetto, Giovanni; Boscolo-Berto, Rafael; Viel, Guido; Montisci, Massimo

    2016-01-01

    Asphyxial deaths are common in forensic practice, being sustained by a variety of mechanisms that cause an oxygen deficiency to the brain. Several classification models have been proposed in the literature, the most recent one being that of the International Network for Forensic Research Group (INFOR). This report describes an unusual case of suffocation where the obstruction of the airways was caused by a gag formed of three latex gloves and a handkerchief. The manner of death (differential diagnosis between homicide and suicide) and the different alternatives of classification are discussed.

  9. Antiplasmodial benzophenones from the trunk latex of Moronobea coccinea (Clusiaceae).

    PubMed

    Marti, Guillaume; Eparvier, Véronique; Moretti, Christian; Susplugas, Sophie; Prado, Soizic; Grellier, Philippe; Retailleau, Pascal; Guéritte, Françoise; Litaudon, Marc

    2009-01-01

    In an effort to find antimalarial drugs, a systematic in vitro evaluation on a chloroquine-resistant strain of Plasmodium falciparum (FcB1) was undertaken on sixty plant extracts collected in French Guiana. The methanol extract obtained from the latex of Moronobea coccinea exhibited a strong antiplasmodial activity (95% at 10microg/ml). The phytochemical investigation of this extract led to the isolation of eleven polycyclic polyprenylated acylphloroglucinols (PPAPs), from which eight showed potent antiplasmodial activity with IC50 ranged from 3.3microM to 37.2microM.

  10. 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.

  11. Fiber reinforced concrete solar collector

    SciTech Connect

    Slemmons, A. J.; Newgard, P. J.

    1985-05-07

    A solar collector is disclosed comprising a glass member having a solar selective coating thereon, and a molded, glass-reinforced concrete member bonded to the glass member and shaped to provide a series of passageways between the glass member and the fiber-reinforced concrete member capable of carrying heat exchanging fluid therethrough. The fiber-reinforced concrete member may be formed by spraying a thin layer of concrete and chopped fibers such as chopped glass fibers onto a mold to provide an inexpensive and lightweight, thin-walled member. The fiber-reinforced concrete member may have a lightweight cellular concrete backing thereon for insulation purposes. The collector is further characterized by the use of materials which have substantially matching thermal coefficients of expansion over the temperature range normally encountered in the use of solar collectors.

  12. Latex agglutination: diagnose the early cryptococcus neoformans test of capsular polysaccharide antigen.

    PubMed

    Wang, Huanrong; Yuan, Xueqian; Zhang, Lifeng

    2015-01-01

    This paper aims to discuss the early diagnosis value of latex agglutination test in Cryptococcal meningitis. The cerebrospinal fluid (CSF) of 112 patients with definite Cryptococcal meningitis and 26 patients with tubercular meningitis and virus meningitis were collected, latex agglutination test is adopted to detect Cryptococcal capsular polysaccharide antigen. Then it was compared with fungal culture and direct microscopy method for evaluating the sensitivity and specificity of the diagnosis. The sensitivity of three methods including latex agglutination test, fungal culture and direct microscopy was 91.1%,69.6% and 73.2% respectively. The specificity of latex agglutination test was 96.0%, 100% and 100% respectively. That latex agglutination test to detect Cryptococcal capsular polysaccharide antigen could be taken as the early diagnostic method of Cryptococcus neoformans meningitis.

  13. Monodisperse Latex Reactor (MLR): A materials processing space shuttle mid-deck payload

    NASA Technical Reports Server (NTRS)

    Kornfeld, D. M.

    1985-01-01

    The monodisperse latex reactor experiment has flown five times on the space shuttle, with three more flights currently planned. The objectives of this project is to manufacture, in the microgravity environment of space, large particle-size monodisperse polystyrene latexes in particle sizes larger and more uniform than can be manufactured on Earth. Historically it has been extremely difficult, if not impossible to manufacture in quantity very high quality monodisperse latexes on Earth in particle sizes much above several micrometers in diameter due to buoyancy and sedimentation problems during the polymerization reaction. However the MLR project has succeeded in manufacturing in microgravity monodisperse latex particles as large as 30 micrometers in diameter with a standard deviation of 1.4 percent. It is expected that 100 micrometer particles will have been produced by the completion of the the three remaining flights. These tiny, highly uniform latex microspheres have become the first material to be commercially marketed that was manufactured in space.

  14. An ESEM investigation of latex film formation in cement pore solution

    SciTech Connect

    Gretz, M.; Plank, J.

    2011-02-15

    Environmental scanning electron microscopy (ESEM) and complementary methods were employed to study the time dependent film formation of a latex dispersion in water and cement pore solution. First, a model carboxylated styrene/n-butyl acrylate latex dispersion possessing a minimum film forming temperature (MFFT) of 18 {sup o}C was synthesized in aqueous media via emulsion polymerization. Its film forming property was at a temperature of 40 {sup o}C, studied under an ESEM. The analysis revealed that upon removal of water, film formation occurs as a result of particle packing, particle deformation and finally particle coalescence. Film formation is significantly retarded when the latex dispersion is present in cement pore solution. This effect can be ascribed to adsorption of Ca{sup 2+} ions onto the surface of the anionic latex particles and to interfacial secondary phases. This layer of adsorbed Ca{sup 2+} ions hinders interdiffusion of the macromolecules and subsequent film formation of the latex polymer.

  15. 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.

  16. 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.

  17. 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.

  18. Fire Resistance of Geopolymer Concretes

    DTIC Science & Technology

    2010-03-21

    1 Project report – Grant FA23860814096, "Fire resistance of geopolymer concretes" – J. Provis, University of Melbourne 1. Background and...experimental program This project provided funding for us to carry out fire testing of geopolymer concrete specimens and associated laboratory...testing. The focus of this report will be the outcomes of the series of pilot-scale (4’×4’×6”) tests on geopolymer concrete panels, which were conducted

  19. 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.

  20. Development of an Economical Method to Reduce the Extractable Latex Protein Levels in Finished Dipped Rubber Products

    PubMed Central

    Perera, Ambegoda Liyanage Harini Amalka

    2017-01-01

    Natural rubber latex (NRL) allergy is caused by the extractable latex proteins in dipped rubber products. It is a major concern for the consumers who are sensitive to the allergenic extractable proteins (EP) in products such as NRL gloves. Objective of this research was to develop an economical method to reduce the EP in finished dipped NRL products. In order to reduce the EP levels, two natural proteases, bromelain from pineapple and papain from papaya, were extracted and partially purified using (NH4)2SO4. According to the newly developed method, different glove samples were treated with a 5% solution of each partially purified enzyme, for 2 hours at 60°C. Residual amounts of in treated samples were quantified using the modified Lowry assay (ASTM D5712-10). Bromelain displayed a 54 (±11)% reduction of the EP from the dipped rubber products, whereas it was 58 (±8)% with papain. These results clearly indicate that the selected natural proteases, bromelain, and papain contribute significantly towards the reduction of the total EP in finished NRL products. Application of bromelain enzyme for the aforementioned purpose has not been reported up to date, whereas papain has been used to treat raw NRL towards reducing the EP. PMID:28706952

  1. The influence of aggregation of latex particles on membrane fouling attachments & ultrafiltration performance in ultrafiltration of latex contaminated water and wastewater.

    PubMed

    Abdelrasoul, Amira; Doan, Huu; Lohi, Ali; Cheng, Chil-Hung

    2017-02-01

    The goal of the present study was to investigate the influence of latex particle aggregation on membrane fouling attachments and the ultrafiltration performance of simulated latex effluent using Cetyltrimethyl Ammonium Bromide (CTAB) as a cationic surfactant. Hydrophilic polysulfone and ultrafilic flat heterogeneous membranes, with molecular weight cut off (MWCO) of 60,000 and 100,000, respectively, as well as hydrophobic polyvinylidene difluoride with MWCO of 100,000, were used under a constant flow rate and cross-flow mode in ultrafiltration of latex solution. In addition, a polycarbonate flat membrane with uniform pore size of 0.05μm was likewise used during the experiment. The effects of CTAB on the latex particle size distribution were investigated at various concentrations, different treatment times, and diverse agitation duration times. The effects of CTAB on the zeta potential of membrane surfaces and latex particles were also investigated. The data obtained indicate that the particle size distribution of treated latex effluent experienced significant shifts in the peaks toward a larger size range caused by the aggregation of particles. As a result, the mass of fouling contributing to pore blocking and the irreversible fouling were noticeably reduced. The optimum results occurred in the instance when CTAB was added at the critical micelle concentration of 0.36g/L, for the duration of 10min and with minimal agitation. Notably, a higher stirring rate had an overall negative effect on the membrane fouling minimization.

  2. Microstructure development in latex coatings: High-resolution cryo-scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Ge, Haiyan

    2005-07-01

    High-resolution cryogenic scanning electron microscopy (Cryo-SEM) was used to investigate microstructure development in drying latex coatings: from a colloidal stable suspension into a coherent strong film by drying. Useful sample preparation artifacts during the freeze-fracture, i.e., pullouts were documented and analyzed. Pullouts indicate both physical properties of latex particles and the drying stages in latex coatings. The mechanism of pullout formation was studied both theoretically and experimentally. Latex coatings must possess satisfactory freeze-thaw stability to avoid problems during transportation and storage in cold winter. The behavior of latex particles during freeze-thaw cycles was visualized by Cryo-SEM. The images indicated that high concentration of polymerizable surfactant in a latex suspension improved its freeze-thaw stability. In film formation, skinning was captured from edge in and top down in coatings of 80nm diameter styrene-butadiene latex particles with exceptional low Tg (-65°C). Effects on skinning of drying conditions and the way the latex was initially stabilized against flocculation were investigated. A skinned pocket was unexpectedly found in the coating. The cause of such a skin around the air bubble was explained by both simple models calculating the dissolution time and force analysis on the particles. The film formation processes in conventional and low volatile organic compound (VOC) latex coatings were compared by time-sectioning Cryo-SEM. Some low-VOC latex coatings were found to dry as fast as conventional ones without deteriorating final good film properties.

  3. Randomized crossover trial comparing the eZ.on plastic condom and a latex condom.

    PubMed

    Cook, L; Nanda, K; Taylor, D

    2001-01-01

    This randomized crossover trial compared the breakage and slippage rates, safety, and acceptability of the recently developed polyurethane bi-directional eZ.on condom with a marketed latex condom. Three hundred sixty couples were asked to use 4 eZ.on condoms and 4 latex condoms. Like several other non-latex condoms tested to date, the eZ.on condom had a higher clinical breakage rate than its latex comparator, while the slippage rates were similar. The clinical breakage rate for the eZ.on condom was 5.6%, compared with 0.9% for the latex condom (difference = 4.76%, with upper 95% confidence bound on the difference = 6.26%). Thus, based on an a priori definition of a 2% clinically acceptable difference, the study failed to conclude equivalence relative to clinical breakage. The complete slippage rate for eZ.on was 1.6%; compared to 0.7% for latex (difference = 0.87%, with upper 95% confidence bound = 1.55%). Thus, based on an a priori definition of a 2% difference we concluded equivalence relative to complete slippage. The safety profile of the eZ.on condom was good and similar to the latex condom. The eZ.on was also found to be easier to don and remove than the latex condom. Although no overall preference existed for either condom, nearly 30%women and men strongly preferred the eZ.on condom to the latex condom. The eZ.on condom may be an acceptable alternative for couples unable or unwilling to use latex condoms.

  4. [Failure of sublingual immunotherapy to treat latex allergy. A report of a case].

    PubMed

    Morfin Maciel, Blanca María; Castillo Morfin, Blanca María

    2008-01-01

    Natural rubber latex has been in widespread use for over a century. Reports of immediate hypersensitivity to latex have increased dramatically since the first case was reported in 1979, specially in persons with cumulative latex exposure. A 13 year old male was referred to our office. He had been wearing orthodontic rubber bands for two years. The previous year he started having itchy, red and watery eyes, with sneezing and runny nose when he was exposed to rubber products. Then he developed oral edema and lip ulcers. Finally, he experienced cough, wheezing, chest tightness and dyspnea. The patient had no history of undergoing surgery, and his mother denied pacifier use. He had no history of fruit and vegetables allergy. Physical examination revealed conjunctival hyperemia, with fine papillary response in the upper tarsal plate, hyaline rhinorrhea, turbinate hypertrophy and perioral ulcers. Skin prick test were positive for latex and Quercus albus. Patch test with latex glove was negative, but positive with rubber tourniquet. Total IgE was 365 UI/mL. Latex-specific IgE testing confirmed the diagnosis. Spirometric values were normal. He started rush sublingual immunotherapy with latex extract. When he had finished, he traveled abroad. At immigration the inspectors examined him with latex gloves. Immediately he developed anaphylaxis, needing urgent medical attention. Although the efficacy and safety of sublingual immunotherapy for latex allergy has been demonstrated, the most effective strategy is complete avoidance of latex-containing products. World Public Health Services must promote the use of synthetic elastomer gloves in airports worldwide.

  5. [Follow-up of allergic symptoms in a group of health workers sensitized to latex].

    PubMed

    De Zotti, R; Muran, A; Negro, C

    2000-01-01

    We studied 28 health care workers sensitised to latex and complaining of respiratory symptoms at work. All were females, aged 32 y (median), and had worked in the hospital for 12 y, in departments with high exposures (22 cases), moderate exposure (4 cases) or low exposure (2 cases) to rubber gloves. Twenty also complained of latex skin symptoms. Twenty-five (89%) were atopical (by prick test), and 16 (57%) had a personal history of allergic disease. Nine (32%) also had symptoms from exposure to latex outside work and 3 (10%) from food cross-reacting with latex. The specific inhalation test with latex gloves confirmed the diagnosis of asthma in 4 cases (14%) and of rhinitis in 13 cases (46%). We reinvestigated the workers 14 months (median) after the first examination to update exposure to latex, any allergic symptoms and adverse effects of relocation. At the follow-up, 3 workers (11%) had retired, all the others had stopped wearing powdered latex gloves, and 12 had changed their duties or the work-place. Ten (40%) of the 25 subjects still at work were without symptoms, 14 (56%) occasionally complained of mild symptoms and one of frequent rhinitis. Overall, we observed improvement of skin symptoms in 74% (14/19) of the cases and of respiratory symptoms in 56% (14/25) of the cases. Symptoms from exposure to latex outside work were still present in 6 subjects. The persistence of symptoms at work was significantly higher among workers who continued to work in departments with high/moderate latex glove exposure. The results of the study show that skin and respiratory symptoms among health care workers are related to the use of powdered latex gloves and confirm the importance of primary prevention.

  6. 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.

  7. 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

  8. 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. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Preparation of large-particle-size monodisperse latexes in space

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Results are reported of latex sphere polymerization experiments performed on two flights of the Columbia and three flights of the Challenger. The trials were carried out because polymerization of the spheres in space avoids coagulation, nucleation of a new crop of particles, and excessive stirring requirements, and allows growth of spheres larger than 4 microns diam. The Monodisperse Latex Reactor (MLR) held four stirred 100 cc sealed stainless steel cylindrical containers. The mixtures were monitored for the conversion times, volume decreases as spheres formed and the mixture temperature. The spheres were grown from 0.19 micron seeds. Details of the flight preparation efforts are outlined. In flights which did not experience mechanical malfunctions spheres 3-30 microns diam were grown that had noticeably lower size variations than did the ground-based control particles. The 10 micron diam spheres grown on STS-6 were accepted as standard reference material by the NBS and became the first products made in space to be commercially sold on earth; the 30 micron spheres also became NBS standards. The experiments confirmed all projected benefits of producing the spheres in space, as well as provided the opportunity to grow more larger offsize spheres by finishing the growths on earth.

  10. The influence of particle size on latex colloid deposition kinetics

    SciTech Connect

    Litton, G.M.; Olson, T.M.

    1995-12-01

    The influence of particle size on the deposition kinetics of latex colloids in packed-bed columns was investigated in the presence of sodium dodecyl sulfate. Deposition rates, expressed as attachment efficiencies, were determined with 245, 481, and 755 nm carboxyl and 248 and 753 nm sulfate latex microspheres in granular quartz beds as a function of ionic strength. Experiments were performed at pH 10 in the presence of 10{sup -3} M sodium dodecyl sulfate to mask possible hydrophobic regions on the interacting surfaces. The onset of unfavorable filtration conditions and the sensitivity of the experimental attachment efficiencies, {alpha}{sub exp}, to changes in the ionic strength were both particle size dependent. However, both effects were opposite to that predicted by DLVO theory based on the primary interaction energy barrier height. Correlations of {alpha}{sub exp} with the secondary minimum showed that as attachment efficiencies approached 1 the depth of the secondary well increased. These observations suggest that particles may be retained within the secondary minimum even when a primary energy barrier is sufficient to inhibit attachment.

  11. Salt induced polystyrene latex flocs investigated by neutron scattering.

    PubMed

    Kwaambwa, Habauka M; Hellsing, Maja S; Wasbrough, Matthew J; Bleuel, Markus; Rennie, Adrian R

    2017-11-01

    Studies with a model system consisting of polystyrene latex particles showed that the protein from seeds of Moringa trees adsorbs to the surface and causes flocculation as unusually dense aggregates. In this study, electrolytes sodium chloride (NaCl), ferric chloride (FeCl3) and aluminium sulfate (Al2(SO4)3) have been used to aggregate model polystyrene particles. The study augments previous work using neutron scattering on the flocculation of polystyrene latex with protein from seeds of Moringa trees that had indicated higher floc dimension, df, values as the concentration of particles increased. The measurements were made using ultra small-angle neutron scattering. Generally the fractal dimension, and thus the floc density, increased with particle concentration and salt concentration. Flocculation was apparent at much lower concentrations of FeCl3 and Al2(SO4)3 than of NaCl. The values of df were found not to simply scale with ionic strength for the three electrolytes studied with FeCl3 being the most effective flocculating agent. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Extract from Calotropis procera latex activates murine macrophages.

    PubMed

    Seddek, Abdel latif Shaker; Mahmoud, Motamed Elsayed; Shiina, Takahiko; Hirayama, Haruko; Iwami, Momoe; Miyazawa, Seiji; Nikami, Hideki; Takewaki, Tadashi; Shimizu, Yasutake

    2009-07-01

    Calotropis procera latex has long been used in traditional medicines. Extracts from C. procera latex have been reported to have various pharmacological actions, including protection from myocardial infarction, hepatoprotective action, antitumor activity, antinociceptive, and pro- and anti-inflammatory actions. To evaluate the immunomodulatory functions of the water-soluble C. procera extract (CPE), we investigated its ability to activate macrophages-effector cells in inflammatory and immune responses. Intraperitoneal injection of CPE in mice (2 mg/mouse) induced migration of macrophages to the intraperitoneal cavity, confirming the proinflammatory effects of water-soluble CPE. The direct effects of CPE on macrophages were then assessed by measuring the production of nitric oxide (NO) as an indicator for macrophage activation. Addition of CPE (1-10 microg/ml) to the culture medium of the murine monocyte/macrophage cell line RAW264.7 caused an increase in NO production in a time- and dose-dependent manner. CPE-elicited NO production was blocked by application of an inhibitor of inducible nitric oxide synthase (iNOS). Expression of iNOS mRNA was induced by treatment of cultured macrophages with CPE. Injection of CPE in mice also resulted in an increase in plasma NO level. The results suggest that CPE activates macrophages and facilitates NO production via up-regulation of iNOS gene expression.

  13. Ocular toxicity by latex of Calotropis procera (Sodom apple)

    PubMed Central

    Basak, Samar K; Bhaumik, Arup; Mohanta, Ayan; Singhal, Prashant

    2009-01-01

    We report the spectrum of ocular toxicity following accidental inoculation of latex of Calotropis procera (Sodom apple) in 29 eyes between January 2003 and December 2006. All patients presented with sudden painless dimness of vision with photophobia. Twenty-five (86%) patients had initial visual acuity of less than 20/60. All eyes had conjunctival congestion and mild to severe corneal edema with Descemet's folds. Three (10%) eyes had an epithelial defect, nine (31%) had iridocyclitis, and seven (24%) had associated secondary glaucoma. After treatment with topical corticosteroids, antiglaucoma agents, cycloplegics, hypertonic saline and tears supplements, 27 (93%) eyes recovered completely within 3–14 days. After three months, 17 (74%) out of 23 eyes showed a significant low endothelial cell count compared to the normal fellow eye (P < 0.001). The latex of Calotropis procera causes significant ocular morbidity which may be preventable by simple health education. The long-term effect on corneal endothelium has to be studied further. PMID:19384022

  14. 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.

  15. Preparation of large-particle-size monodisperse latexes in space

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Results are reported of latex sphere polymerization experiments performed on two flights of the Columbia and three flights of the Challenger. The trials were carried out because polymerization of the spheres in space avoids coagulation, nucleation of a new crop of particles, and excessive stirring requirements, and allows growth of spheres larger than 4 microns diam. The Monodisperse Latex Reactor (MLR) held four stirred 100 cc sealed stainless steel cylindrical containers. The mixtures were monitored for the conversion times, volume decreases as spheres formed and the mixture temperature. The spheres were grown from 0.19 micron seeds. Details of the flight preparation efforts are outlined. In flights which did not experience mechanical malfunctions spheres 3-30 microns diam were grown that had noticeably lower size variations than did the ground-based control particles. The 10 micron diam spheres grown on STS-6 were accepted as standard reference material by the NBS and became the first products made in space to be commercially sold on earth; the 30 micron spheres also became NBS standards. The experiments confirmed all projected benefits of producing the spheres in space, as well as provided the opportunity to grow more larger offsize spheres by finishing the growths on earth.

  16. Accelerated design and quality control of impact modifiers for plastics through atomic force microscopy (AFM) analysis

    NASA Astrophysics Data System (ADS)

    Moeller, Gunter

    2011-03-01

    Standard polymer resins are often too brittle or do not meet other mechanical property requirements for typical polymer applications. To achieve desired properties it is common to disperse so called ``impact modifiers'', which are spherical latex particles with diameters of much less than one micrometer, into the pure resin. Understanding and control of the entire process from latex particle formation to subsequent dispersion into polymer resins are necessary to accelerate the development of new materials that meet specific application requirements. In this work AFM imaging and nanoindentation techniques in combination with AFM-based spectroscopic techniques were applied to assess latex formation and dispersion. The size and size distribution of the latex particles can be measured based on AFM amplitude modulation images. AFM phase images provide information about the chemical homogeneity of individual particles. Nanoindentation may be used to estimate their elastic and viscoelastic properties. Proprietary creep and nanoscale Dynamic Mechanical Analysis (DMA) tests that we have developed were used to measure these mechanical properties. The small size of dispersed latex inclusions requires local mechanical and spectroscopic analysis techniques with high lateral and spatial resolution. We applied the CRAVE AFM method, developed at NIST, to perform mechanical analysis of individual latex inclusions and compared results with those obtained using nanoscale DMA. NanoIR, developed by Anasys Inc., and principal component confocal Raman were used for spectroscopic analysis and results from both techniques compared.

  17. Specific IgE response to purified and recombinant allergens in latex allergy

    PubMed Central

    Kurup, Viswanath P; Sussman, Gordon L; Yeang, Hoong Y; Elms, Nancy; Breiteneder, Heimo; Arif, Siti AM; Kelly, Kevin J; Bansal, Naveen K; Fink, Jordan N

    2005-01-01

    Background In recent years, allergy to natural rubber latex has emerged as a major allergy among certain occupational groups and patients with underlying diseases. The sensitization and development of latex allergy has been attributed to exposure to products containing residual latex proteins. Although improved manufacturing procedures resulted in a considerable reduction of new cases, the potential risk for some patient groups is still great. In addition the prevalent cross-reactivity of latex proteins with other food allergens poses a major concern. A number of purified allergens and a few commercial kits are currently available, but no concerted effort was undertaken to evaluate them. Methods We studied 11 purified latex allergens, Hev b 1 to Hev b 10, and Hev b 13 along with several crude allergen extracts and two commercial ImmunoCAP assays to evaluate specific IgE antibody in the sera from latex allergic patients and controls. Health care workers and spina bifida patients with clinical symptoms of latex allergy, spina bifida patients without latex allergy, and non-atopic health care workers have been studied. Results The results suggest that Hev b 2, 5, 6, and 13 together identified over 80 percent health care workers with latex allergy, while Hev b 6 along with Hev b 1 or 3 detected specific IgE antibody in all sera studied from patients with spina bifida and latex allergy. The ImmunoCAP results using both Hev b 5 amplified and non-amplified closely agreed with the clinical diagnosis of latex allergy in health care workers and in spina bifida. Conclusion Although the purified allergens and crude extracts reacted diversely with IgE from different patient groups, the results indicated that use of certain combinations of purified recombinant antigens will be useful in commercial kits or in in-house assays for detecting specific IgE antibody in the sera. The results suggest that a combination of Hev b 2, 3, 5, 6, and 13 together detected specific IgE in 80% of

  18. Evaluation of the osteogenic potential of Hancornia speciosa latex in rat calvaria and its phytochemical profile.

    PubMed

    Dos Santos Neves, Juliana; Franchin, Marcelo; Rosalen, Pedro Luiz; Omar, Nadia Fayez; Dos Santos, Mariana Albuquerque; Paschoal, Jonas Augusto Rizzato; Novaes, Pedro Duarte

    2016-05-13

    Hancornia speciosa Gomes, commonly known as Mangabeira, is a Brazilian native fruit tree belonging to the Apocynaceae family. In folk medicine, the latex obtained from Mangabeira's trunk has been used as an adjunct therapy for bone fractures. Few pharmacological studies on the Hancornia speciosa latex have been developed and despite its popular use for bone healing there is no data about its biological effect on bone. The present study aimed to investigate the osteogenic potential of Hancornia speciosa latex in rat calvaria, as well as its phytochemical profile. A neutral gel composition containing 5% latex was topical applied to a critical size bone defect and over intact calvaria of rats. Areas of newly formed bone on the borders of the defect and of calvaria periosteum were quantified, as well as the percentage of BrdU-positive cells and total cells in the periosteum at different periods of time after latex application. The cytotoxicity of the latex aqueous phase was evaluated in rat calvarial cells in vitro by MTT assay and its phytochemical profile was investigated by ESI-MS/MS. The area of newly formed bone on the borders of the calvaria defect was larger in rats that received latex at 15 and 30 days of healing. After 3 days of latex application over the intact calvaria, the periosteum area was increased and newly formed bone was observed after 5 and 11 days. There was also an increase in periosteum cell proliferation and population followed latex application on calvaria (p<0.05). The latex aqueous phase limited rat calvarial cell viability in vitro in concentrations larger than 0.6mg/mL. Chlorogenic acid and naringenin-7-O-glucoside were identified in the latex aqueous phase, along with catechin and procyanidin compounds. There was a stimulus for periosteum cell proliferation and bone formation when Hancornia speciosa latex was topically applied on rat calvaria. In addition, chlorogenic acid and naringenin-7-O-glucoside present in Hancornia speciosa latex

  19. 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.

  20. Characterization of typo-, regio-, and stereo-selectivities of babaco latex lipase in aqueous and organic media.

    PubMed

    Cambon, E; Rodriguez, J A; Pina, M; Arondel, V; Carriere, F; Turon, F; Ruales, J; Villeneuve, P

    2008-04-01

    The unripe fruit of babaco (Vasconcellea x heilbornii; syn. Carica pentagona) contains a latex, similar to that in Carica papaya, which exhibits lipolytic activity. Herein, the regioselectivity, stereoselectivity and typoselectivity in both hydrolysis and acyltransfer reactions of babaco latex lipases were studied and compared to those of Carica papaya latex. In hydrolysis, both biocatalysts are 1,3-regioselective with ratios for 1,2-2,3-diacylglycerols/1,3-diacylglycerol of 6.5 and 21 for babaco and papaya, respectively. In contrast, papaya latex had a slight sn-3 stereopreference. Babaco latex displayed a higher activity on triacylglycerols with short chain and unsaturated fatty acids.