WorldWideScience

Sample records for chain latex particles

  1. Facile Fabrication of Water Dispersible Latex Particles with Homogeneous or Chain-Segregated Surface from RAFT Polymerization Using a Mixture of Two Macromolecular Chain Transfer Agents.

    Science.gov (United States)

    Sun, Li; Hong, Liangzhi; Wang, Chaoyang

    2016-04-01

    Water dispersible latex particles with randomly mixed shells or chain segregated surface are synthesized from one-pot reversible addition-fragmentation chain transfer heterogeneous polymerization of benzyl methacrylate (BzMA) using a mixture of poly(glycerol monomethacrylate) (PGMA) and poly(2,3-bis(succinyloxy)propyl methacrylate) (PBSPMA) macromolecular chain transfer agents. In methanol, the two in situ synthesized PGMA-b-PBzMA and PBSPMA-b-PBzMA diblock copolymers coaggregate into spherical micelles, which contain PBzMA core and discrete PGMA and PBSPMA nanodomains on the shell. In contrast, in water-methanol mixture (V/V = 9/1), latex particles with homogeneous distribution of PGMA and PBSPMA polymer chains on the shell are obtained. The reasons leading to formation of latex particles with homogenous or chain-segregated surface are discussed, and polymerization kinetics and physical state of PBSPMA in methanol and water-methanol mixtures are ascribed. These polymeric micelles with patterned functional group on the surface are potentially important for application in supracolloidal hierarchical assemblies and catalysis.

  2. The Morphology of Emulsion Polymerized Latex Particles

    Science.gov (United States)

    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.

  3. Self-assembly of latex particles for colloidal crystals

    Institute of Scientific and Technical Information of China (English)

    Zhirong Li; Jingxia wang; Yanlin Song

    2011-01-01

    Self-assembly of latex particles is of great importance for fabricating various functional colloidal crystals.In this paper,we review recent research on the self-assembly of latex particles for colloidal crystals,covering the assembly forces and various assembly approaches of latex particles,including self-assembly by gravity sedimentation,vertical deposition,physical confinement,electric field,and magnetic field.Furthermore,some simple methods for assembling latex particles such as spin coating,spray coating,and printing are also summarized.

  4. PREPARATION OF HOLLOW LATEX PARTICLES BY ALKALI-ACID TREATMENT

    Institute of Scientific and Technical Information of China (English)

    郝冬梅; 王新灵; 朱卫华; 唐小真; 刘成岑; 施凯

    2001-01-01

    Hollow polymer latex particles were prepared by seeded emulsion polymerization. A seed latex consisting of styrene (St), butyl acrylate(BA) copolymer was first prepared, and seeded terpolymerization of St-BA-MA(methacrylic acid) were then carried out in the absence of surfactant. Final latex was treated by a two-step treatment under alkaline and acidic conditions, thus, the particles with hollow structure were obtained. We discussed the effects of pH value, temperature and time in alkali and acid treatment processes on hollow structure within the polymer latex particles and amount of carboxylic group on particle surface. The results show that the hollow polymer latex particles with the largest hollow size can be obtained under a certain condition (pH12.5, 90°C, 3 h in alkali treatment stage and pH2.5, 85°C, 3 h in acid treatment stage).

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

    Science.gov (United States)

    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.

  6. The formation of small scale granularities in latex particles

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. The Synthesis and Modification of Nanosized Clickable Latex Particles

    KAUST Repository

    Almahdali, Sarah

    2013-05-01

    This research aims to add to the current knowledge available for miniemulsion polymerization reactions and to use this knowledge to synthesize multifunctional nanosized latex particles that have the potential to be used in catalysis. The physical properties of the latex can be adjusted to suit various environments due to the multiple functional groups present. For this research, styrene, pentafluorostyrene, azidomethyl styrene, pentafluorostyrene with azidomethyl styrene and pentafluorostyrene with styrene latexes were produced, and analyzed by dynamic light scattering. The latexes were synthesized using a miniemulsion polymerization technique found through this research. Potassium oleate and potassium 1,1,2,2,3,3,4,4-nonafluorobutane-1-sulfonate were used as surfactants during the miniemulsion polymerization reaction to synthesize pentafluorostyrene with azidomethyl styrene latex. Transmission electron microscopy data and dynamic light scattering data have been collected to analyze the structure of this latex, and it has been synthesized using a number of conditions, differing in reaction time, surfactant amount and sonication methods. We have also improved the solubility of the latex through a copper(I) catalyzed 1,3-dipolar azide-alkyne reaction, by clicking (polyethylene glycol)5000 onto the azide functional groups.

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

    Science.gov (United States)

    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.

  10. Morphology and film formation of poly(butyl methacrylate)-polypyrrole core-shell latex particles

    NARCIS (Netherlands)

    Huijs, F; Lang, J

    2000-01-01

    Core-shell latex particles made of a poly(butyl methacrylate) (PBMA) core and a thin polypyrrole (PPy) shell were synthesized by two-stage polymerization. In the first stage, PBMA latex particles were synthesized in a semicontinuous process by free-radical polymerization. PBMA latex particles were l

  11. Human fibrinogen adsorption on positively charged latex particles.

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Georg Bauer

    Full Text Available 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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Tan, Bing; Rankin, Stephen E

    2005-08-30

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

  15. The Growth of Latex Particles during the VAc/BA Copolymerization

    Institute of Scientific and Technical Information of China (English)

    QIN Shaoxiong; LIN Jindong; WANG Juan; ZHANG Xinya; CHEN Huanqin

    2006-01-01

    The semi-continuous seeded emulsion copolymerization of vinyl acetate and butyl acrylate was carried out with hydroxyethyl cellulose as a colloid stabilizer. The morphology of the latex particle and the relationship between the reaction time and the average particle diameter and/or the conversion ratio during the polymerization were investigated. The experimental results show that the morphology of the latex particle possesses the stable steric construction. In the seeded polymerization, the average particle diameter of latex decreased while the conversion ratio increased. At the second term of the emulsion copolymerization (the growth stage of particle size), the latex particle average diameter increased with copolymerization continuously, but the instantaneous conversation ratio was not large, so it was very necessary to properly prolong the time during the holding temperature stage.

  16. Euphorbia characias latex: micromorphology of rubber particles and rubber transferase activity.

    Science.gov (United States)

    Spanò, Delia; Pintus, Francesca; Esposito, Francesca; Loche, Danilo; Floris, Giovanni; Medda, Rosaria

    2015-02-01

    We have recently characterized a natural rubber in the latex of Euphorbia characias. Following that study, we here investigated the rubber particles and rubber transferase in that Mediterranean shrub. Rubber particles, observed by scanning electron microscopy, are spherical in shape with diameter ranging from 0.02 to 1.2 μm. Washed rubber particles exhibit rubber transferase activity with a rate of radiolabeled [(14)C]IPP incorporation of 4.5 pmol min(-1)mg(-1). Denaturing electrophoresis profile of washed rubber particles reveals a single protein band of 37 kDa that is recognized in western blot analysis by antibodies raised against the synthetic peptide whose sequence, DVVIRTSGETRLSNF, is included in one of the five regions conserved among cis-prenyl chain elongation enzymes. The cDNA nucleotide sequence of E. characias rubber transferase (GenBank JX564541) and the deduced amino acid sequence appear to be highly homologous to the sequence of several plant cis-prenyltransferases.

  17. Light scattering of PMMA latex particles in benzene: structural effects

    NARCIS (Netherlands)

    Nieuwenhuis, E.A.; Vrij, A.

    1979-01-01

    Intra- and interparticle structural effects were studied in polymethylmethacrylate (PMMA) latex dispersions in a nonpolar solvent with the technique of light scattering. The required transparency of the dispersions was attained by a close matching of the refractive index of PMMA and solvent, for whi

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

    Science.gov (United States)

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

    2014-10-28

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

  19. Preparation and characterization of latex particles as potential physical shale stabilizer in water-based drilling fluids.

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Junyi Liu

    2014-01-01

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

  1. Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization

    Institute of Scientific and Technical Information of China (English)

    Ji Shuai Wang; Wei Deng; Yun Shen Chen; Cheng You Kan

    2010-01-01

    In this study,P(St-MAA)seed latex particles were first prepared via soap-free emulsion polymerization of styrene(St)and methacrylic acid(MAA),then the seed particles were allowed to swell with St at room temperature,and the P(St-MAA)/P(St-NaSS)core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate(NaSS)using AIBN as initiator in the presence of N,N'-methylenebisacrylamide(BAA,water-soluble crosslinker).Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%,the narrow dispersed P(St-MAA)seed particles with the diameter of 150 nm and the P(St-MAA)/P(St-NaSS)core/shell latexes with the particle size of about 200 nm were synthesized.When the 25/75 mole ratio of NaSS/(St+MAA)and 2 mol% of BAA were used in the seeded emulsion polymerization,the resulted P(St-MAA)/P(St-NaSS)latex product showed a low weight loss after water extraction,and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%,respectively.

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

    Science.gov (United States)

    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.

  3. Physical adsorption of anisotropic titania nanoparticles onto poly(2-vinylpyridine) latex and characterisation of the resulting nanocomposite particles.

    Science.gov (United States)

    Fielding, Lee A; Armes, Steven P; Staniland, Paul; Sayer, Robert; Tooley, Ian

    2014-07-15

    Four poly(2-vinylpyridine) latexes with intensity-average mean diameters ranging between 246 and 955nm were prepared by aqueous emulsion polymerisation. These latexes were characterised by transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, aqueous electrophoresis, disc centrifuge photosedimentometry and thermogravimetry. The adsorption of rice grain-shaped nano-sized titania particles onto the surface of these latex particles from aqueous solution was investigated. It was found that the titania particles adsorb strongly at pH 10 and the optimal loading and packing density of titania was investigated for each latex. The resulting core-shell P2VP-titania nanocomposite particles were characterised in terms of their titania contents, surface coverages and colloidal stabilities. UV-Vis spectra were recorded for the titania nanoparticles, the original P2VP latexes and the poly(2-vinylpyridine)-titania nanocomposite particles. It was found that, for the larger nanocomposite particles, UV-Vis absorption was dominated by the latex core, whereas the smaller P2VP-titania nanocomposite particles exhibited UV attenuation to longer wavelengths compared to both the bare latex and the titania particles. The poly(2-vinylpyridine) cores were selectively removed by calcination of the nanocomposite particles and the resulting hollow titania structures were investigated by transmission electron microscopy.

  4. Latex particle template lift-up guided gold wire-networks via evaporation lithography

    KAUST Repository

    Lone, Saifullah

    2014-01-01

    We describe a hybrid methodology that combines a two dimensional (2D) monolayer of latex particles (with a pitch size down to 1 μm) prepared by horizontal dry deposition, lift-up of a 2D template onto flat surfaces and evaporation lithography to fabricate metal micro- and nano wire-networks. This journal is

  5. MEASUREMENTS OF VOLATILE ORGANIC COMPOUNDS AND PARTICLES DURING APPLICATION OF LATEX PAINT WITH AN AIRLESS SPRAYER

    Science.gov (United States)

    The paper discusses experiments, conducted at EPA's Indoor Air Quality Research House, to measure airborne concentrations of volatile organic compounds (VOCs) and particles during and following the spray-application of latex wall paint. (NOTE: Paint may be applied indoors by a v...

  6. Preparation and characterization of inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles

    Science.gov (United States)

    Bai, Ruiqin; Qiu, Teng; Han, Feng; He, Lifan; Li, Xiaoyu

    2012-07-01

    The inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared via seeded emulsion polymerization of acrylate monomers and octamethylcyclotetrasiloxane (D4) gradually, using functional polymethacryloxypropylsilsesquioxane (PSQ) latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of mixed emulsifiers as seeds. The FTIR spectra show that acrylate monomers and D4 are effectively involved in the emulsion copolymerization and formed the polydimethylsiloxane-containing hybrid latex particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core-shell structure and a narrow size distribution. XPS analysis also indicates that polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared and PDMS is rich in the surface of the hybrid latex film. Additionally, compared with the hybrid latex film without PDMS, the hybrid latex film containing PDMS shows higher hydrophobicity (water contact angle) and lower water absorption.

  7. Preparation and characterization of inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles

    Energy Technology Data Exchange (ETDEWEB)

    Bai Ruiqin [College of Materials Science and Engineering, State Key Laboratory of Organic-Inorganic Composite, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Qiu Teng, E-mail: qiuteng@mail.buct.edu.cn [College of Materials Science and Engineering, State Key Laboratory of Organic-Inorganic Composite, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Han Feng; He Lifan [College of Materials Science and Engineering, State Key Laboratory of Organic-Inorganic Composite, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Li Xiaoyu, E-mail: lixy@mail.buct.edu.cn [College of Materials Science and Engineering, State Key Laboratory of Organic-Inorganic Composite, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2012-07-15

    The inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared via seeded emulsion polymerization of acrylate monomers and octamethylcyclotetrasiloxane (D{sub 4}) gradually, using functional polymethacryloxypropylsilsesquioxane (PSQ) latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of mixed emulsifiers as seeds. The FTIR spectra show that acrylate monomers and D{sub 4} are effectively involved in the emulsion copolymerization and formed the polydimethylsiloxane-containing hybrid latex particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core-shell structure and a narrow size distribution. XPS analysis also indicates that polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared and PDMS is rich in the surface of the hybrid latex film. Additionally, compared with the hybrid latex film without PDMS, the hybrid latex film containing PDMS shows higher hydrophobicity (water contact angle) and lower water absorption.

  8. Antimicrobial films obtained from latex particles functionalized with quaternized block copolymers.

    Science.gov (United States)

    Alvarez-Paino, Marta; Juan-Rodríguez, Rafael; Cuervo-Rodríguez, Rocío; Tejero, Rubén; López, Daniel; López-Fabal, Fátima; Gómez-Garcés, José L; Muñoz-Bonilla, Alexandra; Fernández-García, Marta

    2016-04-01

    New amphiphilic block copolymers with antimicrobial properties were obtained by atom transfer radical polymerization (ATRP) and copper catalyzed cycloaddition following two approaches, a simultaneous strategy or a two-step synthesis, which were proven to be very effective methods. These copolymers were subsequently quaternized using two alkyl chains, methyl and butyl, to amplify their antimicrobial properties and to investigate the effect of alkyl length. Antimicrobial experiments in solution were performed with three types of bacteria, two gram-positive and one gram-negative, and a fungus. Those copolymers quaternized with methyl iodide showed better selectivities on gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, against red blood cells, demonstrating the importance of the quaternizing agent chosen. Once the solution studies were performed, we prepared poly(butyl methacrylate) latex particles functionalized with the antimicrobial copolymers by emulsion polymerization of butyl methacrylate using such copolymers as surfactants. The characterization by various techniques served to test their effectiveness as surfactants. Finally, films were prepared from these emulsions, and their antimicrobial activity was studied against the gram-positive bacteria. The results indicate that the antimicrobial efficiency of the films depends not only on the copolymer activity but also on other factors such as the surface segregation of the antimicrobial agent to the interface.

  9. Plasma etching of polystyrene latex particles for the preparation of graphene oxide nanowalls

    Directory of Open Access Journals (Sweden)

    Bon Bittolo Silvia

    2012-01-01

    Full Text Available Graphene oxide nanowalls were prepared by casting a water dispersion of polystyrene latex particles onto a graphene oxide film followed by tetrafluoromethane plasma etching. Mild plasma etching conditions allow one to retain the oxygen functional groups on the graphene oxide nanowalls. It was found that the exposure to a xenon light source of such graphene oxide nanowalls coated with a gold thin film results in an increase of the electrical conductivity.

  10. MONODISPERSED AND NANOSIZED DENDRIMER/POLYSTYRENE LATEX PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Changfeng Yi; Zushun Xu; Warren T. Ford

    2004-01-01

    Emulsion polymerization of styrene was carried out using dendrimer DAB-dendr-(NH2)64 as seed. The size and size distribution of the emulsion particles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), and the effects of emulsion polymerization conditions on the preparation of emulsion particle were investigated. It has been found that the nanosized dendrimer/polystyrene polymer emulsion particles obtained were in the range of 26~64 nm in diameter, and were monodisperse; the size and size distribution of emulsion particles were influenced by the contents of dendrimer DAB-dendr-(NH2)64, emulsifier and initiator, as well as the pH value.

  11. Preparation of Inert Polystyrene Latex Particles as MicroRNA Delivery Vectors by Surfactant-Free RAFT Emulsion Polymerization.

    Science.gov (United States)

    Poon, Cheuk Ka; Tang, Owen; Chen, Xin-Ming; Pham, Binh T T; Gody, Guillaume; Pollock, Carol A; Hawkett, Brian S; Perrier, Sébastien

    2016-03-14

    We present the preparation of 11 nm polyacrylamide-stabilized polystyrene latex particles for conjugation to a microRNA model by surfactant-free RAFT emulsion polymerization. Our synthetic strategy involved the preparation of amphiphilic polyacrylamide-block-polystyrene copolymers, which were able to self-assemble into polymeric micelles and "grow" into polystyrene latex particles. The surface of these sterically stabilized particles was postmodified with a disulfide-bearing linker for the attachment of the microRNA model, which can be released from the latex particles under reducing conditions. These nanoparticles offer the advantage of ease of preparation via a scaleable process, and the versatility of their synthesis makes them adaptable to a range of applications.

  12. Dynamics of polyelectrolyte adsorption and colloidal flocculation upon mixing studied using mono-dispersed polystyrene latex particles

    NARCIS (Netherlands)

    Feng, Lili; Cohen Stuart, Martien; Adachi, Yasuhisa

    2015-01-01

    The dynamic behavior of polyelectrolytes just after their encounter with the surface of bare colloidal particles is analyzed, using the flocculation properties of mono-dispersed polystyrene latex (PSL) particles. Applying a Standardized Colloid Mixing (SCM) approach, effects of ionic strength and

  13. Preparation of Mosaic Latex Particles%镶嵌型乳胶粒子的合成

    Institute of Scientific and Technical Information of China (English)

    李效玉; 石淑先; 寇奕; 董汉鹏; 夏宇正

    2001-01-01

    A new kind of mosaic latex particles with gradient distribution of hard polymer have been synthesized through two-stage emulsion polymerization based on natural rubber latex.One or two or three of styrene,methyl methacrylate,acrylonitrile,isobornyl acrylate were used as hard monomer in order to prepare interpenetrating polymer network.When oleinic acid was selected as emulsifier,tbutylhydroperoxide-tetraethylene pentamine as oxi-reduction initiation system,the polymerization proceeded for 6 h in natural rubber latex smoothly with the 99% conversion of monomer.The effects of emulsifiers and the initiators on the polymerization were studied; the effects of crosslinker,swelling degree,hard monomer on morphology of the title latex particles were also investigated.The result of morphology analysis of the latex showed that the latex particle was mosaic structure with hard polymer gradient distributed.%以苯乙烯、甲基丙烯酸甲酯、丙烯腈等单体或它们的混合物为硬单体,天然胶乳为弹性组分,经多步种子乳液聚合法制得了在天然胶乳的粒子上镶嵌硬聚合物相的互穿网络型乳胶粒子.考察了十二烷基硫酸钠、十二烷基苯磺酸钠、壬基酚聚氧乙烯醚、油酸等乳化体系,过硫酸钾、过氧化苯甲酰热引发体系及异丙苯过氧化氢-四乙烯五胺、叔丁基过氧化氢-四乙烯五胺等氧化还原引发体系对聚合反应的影响.研究了交联剂用量对互穿结合率、溶胶含量的影响及溶胀时间、硬单体组成、乳化剂种类对乳胶粒子形态的影响,确定了适宜的聚合配方和工艺条件.透射电镜观察乳粒形态结果表明,单一使用极性或非极性单体,仅得到核-壳结构乳液,而采用不同极性单体复合、溶胀、互穿,得到的是镶嵌硬聚合物型乳粒结构.

  14. Latex particle agglutination test as an adjunct to the diagnosis of bacterial meningitis

    Directory of Open Access Journals (Sweden)

    Surinder K

    2007-01-01

    Full Text Available The present study aimed to review the results of microscopic examination, routine culture and antigen detection by latex particle agglutination test (LPAT, in order to evaluate the diagnostic value of the LPAT in establishing the aetiological diagnosis of bacterial meningitis. LPAT was done in 65 clinically suspected meningitis cases ranging from 5 days to 60 years of age and was compared with culture and Gram stain. Using LPAT, an aetiological diagnosis could be done in 10 out of 65 (15.4% cases of bacterial meningitis. In contrast, Gram stain and culture showed 16.9 and 23.1% positivity, respectively. LPAT correlated well with Gram stain and culture and can be recommended as an adjunct laboratory test for rapid aetiological diagnosis of bacterial meningitis for prompt institution of proper antibiotics.

  15. Hollow latex particles functionalized with chitosan for the removal of formaldehyde from indoor air.

    Science.gov (United States)

    Nuasaen, Sukanya; Opaprakasit, Pakorn; Tangboriboonrat, Pramuan

    2014-01-30

    Chitosan and polyethyleneimine (PEI) functionalized hollow latex (HL) particles were conveniently fabricated by coating poly(methyl methacrylate-co-divinyl benzene-co-acrylic acid) (P(MMA/DVB/AA)) HL particles with 5 wt% chitosan or 14 wt% PEI. The materials were used as formaldehyde adsorbent, where their adsorbent activity was examined by Fourier Transform Infrared (FTIR) spectroscopy. The nucleophilic addition of amines to carbonyls generated a carbinolamine intermediate with a characteristic band at 1,020 cm(-1) and Schiff base product at 1650 cm(-1), whose intensity increased with prolonged formaldehyde exposure times. The major products observed in HL-chitosan were carbinolamine and Schiff base, whereas a small amount of Schiff base was obtained in HL-PEI particles, confirming a chemical bond formation without re-emission of formaldehyde. Compared to HL-PEI, HL-chitosan possesses higher formaldehyde adsorption efficiency. Besides providing opacity and whiteness, the multilayer HL-chitosan particles can effectively remove indoor air pollutants, i.e., formaldehyde gas, and, hence, would be useful in special coating applications.

  16. Novel sintering behavior of polystyrene nano-latex particles in filming process

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Filming process of polystyrene nano-latex (NPS) particles was studied by a combination of various methods. For a constant annealing time of 1 h, the AFM images showed that the deformation and sintering temperatures for NPS particles were ca. 90℃ and 100℃ respectively. In spin-lattice relaxation measurements of solid state NMR, it is found that T1L, T1S and I1L/I0 increased significantly after annealing at 90℃ and above. DSC results showed that there was an exothermic peak near Tg after annealing for 1 h at the selected temperatures below 95℃; otherwise, the exothermic peak disappeared after annealing at 100℃ or above. The apparent density of NPS increased suddenly in the tempera-ture range. The results implied that the macromolecules in NPS particles are in a confined state with higher conforma-tional energy and less cohensional interactions which are the drive force for the sintering at a lower temperature com-pared with the multichain PS particles and the bulk polymer.

  17. Single-molecule detection of proteins with antigen-antibody interaction using resistive-pulse sensing of submicron latex particles

    Science.gov (United States)

    Takakura, T.; Yanagi, I.; Goto, Y.; Ishige, Y.; Kohara, Y.

    2016-03-01

    We developed a resistive-pulse sensor with a solid-state pore and measured the latex agglutination of submicron particles induced by antigen-antibody interaction for single-molecule detection of proteins. We fabricated the pore based on numerical simulation to clearly distinguish between monomer and dimer latex particles. By measuring single dimers agglutinated in the single-molecule regime, we detected single human alpha-fetoprotein molecules. Adjusting the initial particle concentration improves the limit of detection (LOD) to 95 fmol/l. We established a theoretical model of the LOD by combining the reaction kinetics and the counting statistics to explain the effect of initial particle concentration on the LOD. The theoretical model shows how to improve the LOD quantitatively. The single-molecule detection studied here indicates the feasibility of implementing a highly sensitive immunoassay by a simple measurement method using resistive-pulse sensing.

  18. Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

    Science.gov (United States)

    Wang, Sai; Liu, Jiahui; Wu, Yanxia; You, Yawen; He, Jingyi; Zhang, Jichuan; Zhang, Liqun; Dong, Yiyang

    2016-04-15

    Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content.

  19. Charge of dust particles in a particle chain

    CERN Document Server

    Yousefi, Razieh; Matthews, Lorin Swint; Hyde, Truell W

    2016-01-01

    Charged dust particles form structures which are extended in the vertical direction in the electrode sheath of a rf discharge when confined within a glass box. The charge on each particle as a function of height varies due to the changing plasma conditions and the wakefield of upstream particles. Here an analysis of the equilibrium state of chains of varying number of particles is analyzed to determine the charge on each particle within a vertically extended chain as well as the magnitude of the positive wakefield charge.

  20. Removal of bisphenol A and some heavy metal ions by polydivinylbenzene magnetic latex particles.

    Science.gov (United States)

    Marzougui, Zied; Chaabouni, Amel; Elleuch, Boubaker; Elaissari, Abdelhamid

    2016-08-01

    In this study, magnetic polydivinylbenzene latex particles MPDVB with a core-shell structure were tested for the removal of bisphenol A (BPA), copper Cu(II), lead Pb(II), and zinc Zn(II) from aqueous solutions by a batch-adsorption technique. The effect of different parameters, such as initial concentration of pollutant, contact time, adsorbent dose, and initial pH solution on the adsorption of the different adsorbates considered was investigated. The adsorption of BPA, Cu(II), Pb(II), and Zn(II) was found to be fast, and the equilibrium was achieved within 30 min. The pH 5-5.5 was found to be the most suitable pH for metal removal. The presence of electrolytes and their increasing concentration reduced the metal adsorption capacity of the adsorbent. Whereas, the optimal pH for BPA adsorption was found 7, both hydrogen bonds and π-π interaction were thought responsible for the adsorption of BPA on MPDVB. The adsorption kinetics of BPA, Cu(II), Pb(II), and Zn(II) were found to follow a pseudo-second-order kinetic model. Equilibrium data for BPA, Cu(II), Pb(II), and Zn(II) adsorption were fitted well by the Langmuir isotherm model. Furthermore, the desorption and regeneration studies have proven that MPDVB can be employed repeatedly without impacting its adsorption capacity.

  1. Comparison of the Freelite serum free light chain (SFLC) assay with serum and urine electrophoresis/immunofixation and the N Latex FLC assay.

    Science.gov (United States)

    Sasson, S C; McGill, K; Wienholt, L; Carr, A; Brown, D A; Kelleher, A D; Breit, S N; Sewell, W A

    2015-10-01

    Few reports have compared available serum free light chain (SFLC) assays. Here, a retrospective audit of the Freelite SFLC assay compared results to electrophoresis (EP)/immunofixation (IFX) and the N Latex FLC assay.A total of 244 samples collected over 3.5 months were studied using the Freelite and N Latex FLC nephelometry assays. Results were compared with serum and/or urine EP/IFX. The precision and linearity of the N Latex FLC assay was examined.Detectable paraprotein by serum or urine EP/IFX was present in 94% of samples with kappa and 100% with lambda FLC restriction. The correlation between the assays was higher for kappa (rho = 0.97) than lambda (rho = 0.89) especially when lambda results were above the upper limit of normal (rho = 0.62). Agreement in the categorical diagnosis as measured by the Cohen's kappa statistic was good (0.70). The N Latex FLC assay displayed good precision and linearity. In discordant samples the Freelite and N Latex FLC assays had equivalent agreement with IFX.Traditional methods of EP/IFX detected paraproteins in the majority of cases. Correlation between the Freelite and N Latex FLC assay is better for kappa than lambda FLC. The two assays are not entirely equivalent. Care should be taken by interpreting physicians and laboratories considering switching assays.

  2. Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

    Science.gov (United States)

    Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

    2014-09-28

    We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

  3. THE SYNTHESIS OF Ag-POLYPYRROLE NANOCOMPOSITE COATED LATEX PARTICLES AND THEIR APPLICATION AS A FLUORESCENT QUENCHING AGENT

    Institute of Scientific and Technical Information of China (English)

    Jiang-ru Zhang; Teng Qiu; Hong-fu Yuan; Xiao-yu Li

    2013-01-01

    Submicron-sized Ag-polypyrrole/poly(styrene-co-methacrylic acid) (Ag-PPy/P(St-co-MAA)) composite particles were fabricated via a redox reaction between pyrrole and AgNO3 in the presence of P(St-co-MAA) soap-free latex.The products are characterized by transmission electron microscopy (TEM),electron diffraction spectra (EDS),Raman spectra,thermogravimetric analysis (TGA) and scanning electron microscopy (SEM).The results showed that Ag-PPy nanocomposites were in situ deposited onto the surface of P(St-co-MAA) latex particles tailored by carboxylic-acid groups.The nanocomposites of Ag-PPy distributed on the surface of polymer particles transformed from discretely dots to continuously coating as the reaction temperature increased from 15℃ to 60℃.Strawberry-like composite particles were obtained at the reaction temperature of 60℃.The TGA characterization confirmed that the Ag-PPy nanocomposites loading onto the P(St-co-MAA) particles were systematically controlled over a range of 6 wt%-42 wt% by changing the reaction temperatures.The fluorescence quenching effect of the Ag-PPy/P(St-co-MAA) composite particles was explored on Rhodamine B as a model molecule with the Stern-V(o)1mer quenching constant Ksv of 5.9 × 104 (g/mL)-1.It is suggested that the fluorescence quenching effect is caused by the resonance energy transfer mechanism.

  4. STUDIES ON POLYSILOXANE-POLYSTYRENE COMPOSITE LATEXES

    Institute of Scientific and Technical Information of China (English)

    HUANG Ying; LIU Xianglian; YU Yunzhao

    1994-01-01

    Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsion polymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in the 2nd-stage polymerization depends on the particle size of the 1st-stage latex and the polymerization temperature. Polystyrene domains in the vulcanizates reinforce the silicone rubbers effectively.

  5. DESIGN AND CONTROL OF SOAP-FREE HYDROPHILIC-HYDROPHOBIC CORE-SHELL LATEX PARTICLES WITH HIGH CARBOXYL CONTENT IN THE CORE OF THE PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Wen-jiao Ji; Yi-ming Jiang; Bo-tian Li; Wei Deng; Cheng-you Kan

    2012-01-01

    Soap-free hydrophilic-hydrophobic core-shell latex particles with high carboxyl content in the core of the particles were synthesized via the seeded emulsion polymerization using methyl methacrylate (MMA),butyl acrylate (BA),methacrylic acid (MAA),styrene (St) and ethylene glycol dimethacrylate (EGDMA) as monomers,and the influences of MMA content used in the core preparation on polymerization,particle size and morphology were investigated by transmission electron microscopy,dynamic light scattering and conductometric titration.The results showed that the seeded emulsion polymerization could be carried out smoothly using "starved monomer feeding process" when MAA content in the core preparation was equal to or less than 24 wt%,and the encapsulating efficiency of the hydrophilic P(MMA-BA-MAA-EGDMA) core with the hydrophobic PSt shell decreased with the increase in MAA content.When an interlayer of P(MMA-MAA-St) with moderate polarity was inserted between the P(MMA-BA-MAA-EGDMA) core and the PSt shell,well designed soap-free hydrophilic-hydrophobic core-shell latex particles with 24 wt% MAA content in the core preparation were obtained.

  6. Polystyrene latex particles containing europium complexes prepared by miniemulsion polymerization using bovine serum albumin as a surfactant for biochemical diagnosis.

    Science.gov (United States)

    Aikawa, Tatsuo; Mizuno, Akihiro; Kohri, Michinari; Taniguchi, Tatsuo; Kishikawa, Keiki; Nakahira, Takayuki

    2016-09-01

    Luminescent particles have been attracting significant attention because they can be used in biochemical applications, such as detecting and imaging biomolecules. In this study, luminescent polystyrene latex particles were prepared through miniemulsion polymerization of styrene with dissolved europium complexes in the presence of bovine serum albumin (BSA) and poly(ethylene glycol) monomethoxy methacrylate as surfactants. The solubility of the europium complex in styrene has a strong effect on the yield of the particle. Europium tris(2-thenoyl trifluoroacetonate) di(tri-n-octyl phosphine oxide), which has a high solubility in styrene, was sufficiently incorporated into the polystyrene particles compared to europium tris(2-thenoyl trifluoroacetonate), which has a low solubility in styrene. The luminescence property of the europium complex could remain intact even after its incorporation through the miniemulsion polymerization. In the aqueous dispersion, the resulting particles could emit strong luminescence, which is a characteristic of the europium complex. The antibody fragments were covalently attached to BSA-covered particles after a reaction with a bifunctional linker, N-(6-maleimidocaproyloxy)succinimide. The time-resolved fluoroimmunoassay technique showed that 3.3pg/mL of human α-fetoproteins (AFP) can be detected by using the resulting luminescent particles. An immunochromatographic assay using the resulting particles was also performed as a convenient method to qualitatively detect biomolecules. The detection limit of AFP measured by the immunochromatographic assay was determined to be 2000pg/mL. These results revealed that the luminescent particles obtained in this study can be utilized for the highly sensitive detection of biomolecules and in vitro biochemical diagnosis.

  7. Colloidal gas-liquid condensation of polystyrene latex particles with intermediate kappa a values (5 to 160, a > kappa(-1)).

    Science.gov (United States)

    Ishikawa, Masamichi; Kitano, Ryota

    2010-02-16

    Polystyrene latex particles showed gas-liquid condensation under the conditions of large particle radius (a > kappa(-1)) and intermediate kappa a, where kappa is the Debye-Hückel parameter and a is the particle radius. The particles were dissolved in deionized water containing ethanol from 0 to 77 vol %, settled to the bottom of the glass plate within 1 h, and then laterally moved toward the center of a cell over a 20 h period in reaching a state of equilibrium condensation. All of the suspensions that were 1 and 3 microm in diameter and 0.01-0.20 vol % in concentration realized similar gas-liquid condensation with clear gas-liquid boundaries. In 50 vol % ethanol solvent, additional ethanol was added to enhance the sedimentation force so as to restrict the particles in a monoparticle layer thickness. The coexistence of gas-liquid-solid (crystalline solid) was microscopically recognized from the periphery to the center of the condensates. A phase diagram of the gas-liquid condensation was created as a function of KCl concentration at a particle diameter of 3 microm, 0.10 vol % concentration, and 50:50 water/ethanol solvent at room temperature. The miscibility gap was observed in the concentration range from 1 to 250 microM. There was an upper limit of salt concentration where the phase separation disappeared, showing nearly critical behavior of macroscopic density fluctuation from 250 microM to 1 mM. These results add new experimental evidence to the existence of colloidal gas-liquid condensation and specify conditions of like-charge attraction between particles.

  8. Measurements of dispersion forces between colloidal latex particles with the atomic force microscope and comparison with Lifshitz theory.

    Science.gov (United States)

    Elzbieciak-Wodka, Magdalena; Popescu, Mihail N; Montes Ruiz-Cabello, F Javier; Trefalt, Gregor; Maroni, Plinio; Borkovec, Michal

    2014-03-14

    Interaction forces between carboxylate colloidal latex particles of about 2 μm in diameter immersed in aqueous solutions of monovalent salts were measured with the colloidal probe technique, which is based on the atomic force microscope. We have systematically varied the ionic strength, the type of salt, and also the surface charge densities of the particles through changes in the solution pH. Based on these measurements, we have accurately measured the dispersion forces acting between the particles and estimated the apparent Hamaker constant to be (2.0 ± 0.5) × 10(-21) J at a separation distance of about 10 nm. This value is basically independent of the salt concentration and the type of salt. Good agreement with Lifshitz theory is found when roughness effects are taken into account. The combination of retardation and roughness effects reduces the value of the apparent Hamaker constant and its ionic strength dependence with respect to the case of ideally smooth surfaces.

  9. Obtaining of a rapid diagnostic test for Cholera, based on latex particles coupled with a monoclonal antibody against Vibrio cholera O1 lipopolysaccharide

    Directory of Open Access Journals (Sweden)

    Fátima Reyes-López

    2015-08-01

    Full Text Available Cholera is an acute contagious intestinal disease caused by ingestion of food or water contaminated with O1 and O139 serotypes of the bacterium Vibrio cholerae. Cholera is characterized by abundant secretory diarrhea leading to dehydration. Death occurs within hours without treatment, so early diagnosis is very important, especially at the beginning of the disease, because it is difficult to differentiate from other acute diarrheal diseases. The diagnostic golden test is the stool culture; however, it does not guarantee a rapid detection of the disease. Rapid tests have been recently developed; they are based on test strips and agglutination with latex particles, which are very effective, but difficult to acquire for their high prices. The objective of this research was to obtain a quick assay based on latex particles coupled with a monoclonal antibody (mAb against V. cholerae O1 lipopolysaccharide obtained in Finlay Institute. Latex particles of 0.8 µm were used in a 10% suspension, and they were coupled to the mAb (0.25 mg/ml for 2 hours at 37°C. The sensitivity, specificity and performance were evaluated in 84 stool samples from patients with presumptive diagnosis of cholera. The diagnostic test obtained showed no cross-reactivity against no-O1 strains and other enteropathogens. Latex diagnostic test showed values of sensitivity, specificity and efficacy of 97.87; 97.29 and 97.6% respectively, very similar to the commercial diagnostic test CTK- Biotech. The latex reagent obtained can be used in the rapid diagnosis of the disease.

  10. Practical Latex

    CERN Document Server

    Grätzer, George

    2014-01-01

    Accessible at 200+ pages to all who want to learn the practical usages of LaTeX Avoids technical subjects like font usage Friendly and easy to read, with many examples included Extra source materials include sample LaTeX files and suggestions for further reading

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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...

  13. Emission spectrum of the atomic chain excited by channeled particle

    CERN Document Server

    Epp, V

    2014-01-01

    Basic properties of radiation of the atomic chains excited by a channeled particle are considered. Using a very simple two-dimensional model of a crystal lattice we have shown that the main part of this radiation is generated on the frequency of oscillations of a channeled particle between the crystal planes, shifted by the Doppler effect. Spectral and angular distribution and spectral distribution of the radiation of the atomic chain excited by channeled particle were calculated. Emission spectrum of the atomic chain excited by channeled particle was plotted.

  14. Testicular biodistribution of 450 nm fluorescent latex particles after intramuscular injection in mice.

    Science.gov (United States)

    Klein, J-P; Boudard, D; Cadusseau, J; Palle, S; Forest, V; Pourchez, J; Cottier, M

    2013-06-01

    The significant expansion in the use of nanoparticles and submicron particles during the last 20 years has led to increasing concern about their potential toxicity to humans and particularly their impact on male fertility. Currently, an insufficient number of studies have focused on the testicular biodistribution of particles. The aim of our study was to assess the distribution of 450 nm fluorescent particles in mouse testes after intramuscular injection. To this end, testes were removed from 5 groups of 3 mice each at 1 h (H1), 4 days (D4), 21 days (D21), 45 days (D45) and 90 days (D90) after the injection of 7.28 × 10⁹ particles in the tibialis anterior muscles of each mouse. We examined histological sections from these samples by epifluorescence microscopy and confocal microscopy and identified testicular biodistribution of a small number of particles in groups H1, D4, D21, D45 and D90. Using CD11b immunostaining, we showed that particles were not carried into the testis by macrophages. The intratesticular repartition of particles mainly followed testicular vascularization. Finally, we found some particles in seminiferous tubules but could not determine if the blood-testis barrier was crossed.

  15. A sensitive three monoclonal antibodies based automatic latex particle-enhanced turbidimetric immunoassay for Golgi protein 73 detection

    Science.gov (United States)

    Xia, Yanyan; Shen, Han; Zhu, Yefei; Xu, Hongpan; Li, Zhiyang; Si, Jin

    2017-01-01

    Golgi protein 73 (GP73) is a novel and potential marker for diagnosing hepatocellular carcinoma (HCC) that has been found to be abnormally elevated in liver disease. A latex particle-enhanced turbidimetric immunoassay (LTIA) was recently introduced and licensed for application in a variety of automated clinical chemistry analyzers. However, no studies have reported sufficient data on analytical performance of this method when using 3 monoclonal antibodies for GP73 measurement. The experimental conditions were firstly optimized and range of linearity, diagnostic potential, clinical relevance were compared with the LTIA based on polyclonal antibodies and ELISA. Dilution tests for the LTIA using 3 monoclonal antibodies produced a calibration curve from 10 to 350 ng/mL while the polyclonal antibodies produced the curve from 20 to 320 ng/mL. The detection limit was achieved at 1.82 ng/mL concentration. Within-run CV was obtained in the range of 1.5–2.9% and ROC curves indicated sensitivity and specificity of the LTIA based on 3 monoclonal antibodies were 96.7% and 93.3%, respectively, higher than for the polyclonal antibodies (94.6% and 72.4%) and ELISA (70.0% and 83.3%). Therefore, the LTIA assay based on 3 monoclonal antibodies is thus applicable in quantification of GP73 concentration in automated biochemistry analyzers. PMID:28054632

  16. Microscale fish bowls: a new class of latex particles with hollow interiors and engineered porous structures in their surfaces.

    Science.gov (United States)

    Jeong, Unyong; Im, Sang Hyuk; Camargo, Pedro H C; Kim, Jung Hyun; Xia, Younan

    2007-10-23

    Microscale fish bowls, hollow particles with engineered holes in their surfaces, were prepared using two different methods. In the first method, commercial latex beads suspended in water were swollen with a good solvent of the polymer, followed by freezing with liquid nitrogen and evaporation of the solvent below 0 degrees C. While one big hole was generated when the amount of solvent used for the swelling was relatively low, small holes could be produced in the outer surface of each bowl by increasing the degree of swelling. The porosity and pore structure show a similar dependence on the degree of swelling for both amorphous and semicrystalline polymers even though they are supposed to exhibit different phase behaviors during the freezing and solvent evaporation processes. In the second method, a polymer emulsion in water was prepared and then frozen with liquid nitrogen, followed by solvent evaporation below 0 degrees C. The porosity and pore structure could be controlled by adjusting the concentration of the polymer solution used to prepare the emulsion. As for encapsulation, the bowl-shaped particles could be transformed back into solid beads via thermal annealing at a temperature near the glass transition temperature of the polymer or by adding a good solvent of the polymer to the colloidal suspension. In a proof-of-concept experiment, microscale fish bowls were fabricated from poly(caprolactone), quickly loaded with a fluorescent dye, and sealed through thermal annealing. The encapsulated dye could then be slowly released in a phosphate buffered saline, suggesting their potential use as a new class of microscale capsules for drug delivery.

  17. Thermodynamic Equilibrium Morphology Prediction of Polyurethane/Polyacrylate Composite Latex Particles

    Institute of Scientific and Technical Information of China (English)

    CHAI Shu-Ling; JIN Ming-Martin

    2008-01-01

    Composite particles were prepared by seeded surfactant-free batch emulsion polymerization at 80 ℃ using K2S2O8 as an initiator, and polyurethane aqueous dispersion as seed particles. The acrylate monomers were continuously added into the reactor under a starving condition in the second stage polymerization. The synthesized hybrid emulsions were found to form an inverted core-shell structure with polyacrylate as the core and with polyurethane as the shell from the observation with a transmission electron microscope. The interfacial tensions between polymer and polymer as well as polymer and water were calculated with a simple method according to harmonic mean equation and used in a mathematical model based on the minimum interfacial energy change principle to predict the equilibrium morphology. The observed particle morphologies were in good agreement with the predicted ones. The surface properties of the dried films formed from polyurethane (PU)/polyacrylate (PA) composite emulsions were also studied by contact angle measurements, showing that the shell part of the composite emulsions is preferentially oriented toward the surface layers of the dried films.

  18. Magnetic relaxation in chain-of-spheres ferromagnetic particles

    CERN Document Server

    Yang, J S

    2002-01-01

    The thermal activation of elongated ferromagnetic particles is analyzed using a chain-of-spheres model. The spheres within the chain are assumed to be coupled magnetically with dipolar interaction. The effect of uniaxial magnetocrystalline anisotropy along the chain is also taken into account. It was shown that the behavior of thermal switching critically depends on the relative strength of shape anisotropy and magnetocrystalline anisotropy, field orientation, sweep field rate and temperature.

  19. The participation ratios of cement matrix and latex network in latex cement co-matrix strength

    Directory of Open Access Journals (Sweden)

    Ahmed M. Diab

    2014-06-01

    Full Text Available This investigation aims to determine the participation ratio of cement matrix and latex network in latex cement co-matrix strength. The first stage of this study was carried out to investigate the effect of styrene butadiene rubber (SBR on cement matrix participation ratio by measuring degree of hydration and compressive strength. The second stage in this study shows an attempt to evaluate the latex participation ratio in mortar and concrete strength with different latex chemical bases. Effect of latex particle size on latex network strength was studied. The test results indicated that the latex participation ratio in co-matrix strength is influenced by type of cement matrix, type of curing, latex type, latex solid/water ratio, strength type and age. For modified concrete, when the SBR solid/water ratio increases the latex participation ratio in flexural and pull out bond strength increases. The latex participation ratio in co-matrix strength decreases as latex particle size increases.

  20. Characterization of rubber particles and rubber chain elongation in Taraxacum koksaghyz

    Directory of Open Access Journals (Sweden)

    Prüfer Dirk

    2010-02-01

    Full Text Available Abstract Background Natural rubber is a biopolymer with exceptional qualities that cannot be completely replaced using synthetic alternatives. Although several key enzymes in the rubber biosynthetic pathway have been isolated, mainly from plants such as Hevea brasiliensis, Ficus spec. and the desert shrub Parthenium argentatum, there have been no in planta functional studies, e.g. by RNA interference, due to the absence of efficient and reproducible protocols for genetic engineering. In contrast, the Russian dandelion Taraxacum koksaghyz, which has long been considered as a potential alternative source of low-cost natural rubber, has a rapid life cycle and can be genetically transformed using a simple and reliable procedure. However, there is very little molecular data available for either the rubber polymer itself or its biosynthesis in T. koksaghyz. Results We established a method for the purification of rubber particles - the active sites of rubber biosynthesis - from T. koksaghyz latex. Photon correlation spectroscopy and transmission electron microscopy revealed an average particle size of 320 nm, and 13C nuclear magnetic resonance (NMR spectroscopy confirmed that isolated rubber particles contain poly(cis-1,4-isoprene with a purity >95%. Size exclusion chromatography indicated that the weight average molecular mass (w of T. koksaghyz natural rubber is 4,000-5,000 kDa. Rubber particles showed rubber transferase activity of 0.2 pmol min-1 mg-1. Ex vivo rubber biosynthesis experiments resulted in a skewed unimodal distribution of [1-14C]isopentenyl pyrophosphate (IPP incorporation at a w of 2,500 kDa. Characterization of recently isolated cis-prenyltransferases (CPTs from T. koksaghyz revealed that these enzymes are associated with rubber particles and are able to produce long-chain polyprenols in yeast. Conclusions T. koksaghyz rubber particles are similar to those described for H. brasiliensis. They contain very pure, high molecular mass

  1. Modal and excitation asymmetries in magnetodielectric particle chains

    Science.gov (United States)

    Mazor, Y.; Steinberg, Ben Z.

    2016-12-01

    We study the properties of dipolar wave propagation in linear chains of isotropic particles with independent electric and magnetic response, embedded in vacuum. It is shown that the chain can support simultaneously right-handed modes (RHMs) and left-handed modes (LHMs) of transverse polarization. The LHMs are supported by the structure even if the chain's particles possess positive polarizabilities and no Bi isotropy; the needed structural Bi isotropy is provided by the propagator instead of by the particle's local properties. In contrast to the transverse modes in chains that consist of purely electric particles that are inherently RHM, the LHM dispersion lacks the light-line branch since the dipolar features are not aligned with the electric and magnetic fields of a right-handed plane-wave solution in free space. Furthermore, it is shown that the spatial width of the LHM is significantly smaller than that of the RHM. Excitation theory is developed, and it is shown that the chain possesses modal and excitation asymmetries that can be used to eliminate reflections from the chain's termination.

  2. Consistent energy barrier distributions in magnetic particle chains

    Energy Technology Data Exchange (ETDEWEB)

    Laslett, O., E-mail: O.Laslett@soton.ac.uk [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom); Ruta, S.; Chantrell, R.W. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Barker, J. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Friedman, G. [Electrical and Computer Engineering Department, Drexel University, Philadelphia, PA 19104 (United States); Hovorka, O. [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom)

    2016-04-01

    We investigate long-time thermal activation behaviour in magnetic particle chains of variable length. Chains are modelled as Stoner–Wohlfarth particles coupled by dipolar interactions. Thermal activation is described as a hopping process over a multidimensional energy landscape using the discrete orientation model limit of the Landau–Lifshitz–Gilbert dynamics. The underlying master equation is solved by diagonalising the associated transition matrix, which allows the evaluation of distributions of time scales of intrinsic thermal activation modes and their energy representation. It is shown that as a result of the interaction dependence of these distributions, increasing the particle chain length can lead to acceleration or deceleration of the overall relaxation process depending on the initialisation procedure.

  3. Stochastic thermodynamics of a tagged particle within a harmonic chain.

    Science.gov (United States)

    Lacoste, David; Lomholt, Michael A

    2015-02-01

    We study the stochastic thermodynamics of an overdamped harmonic chain, which can be viewed equivalently as a one-dimensional Rouse chain or as an approximate model of single file diffusion. We discuss mainly two levels of description of this system: the Markovian level for which the trajectories of all the particles of the chain are known and the non-Markovian level in which only the motion of a tagged particle is available. For each case, we analyze the energy dissipation and its dependence on initial conditions. Surprisingly, we find that the average coarse-grained entropy production rate can become transiently negative when an oscillating force is applied to the tagged particle. This occurs due to memory effects as shown in a framework based on path integrals or on a generalized Langevin equation.

  4. Modal and excitation asymmetries in magneto-dielectric particle chains

    CERN Document Server

    Mazor, Y

    2016-01-01

    We study the properties of dipolar wave propagation in linear chains of isotropic particles with independent electric and magnetic response, embedded in vacuum. It is shown that the chain can support simultaneously right-handed modes (RHM) and left-handed modes (LHM) of transverse-polarization. The LHM are supported by the structure even if the chain's particles possess positive polarizabilities and no Bi-isotropy; the needed structural Bi-isotropy is provided by the propagator instead of by the particle's local properties. In contrast to the transverse modes in chains that consist of purely electric particles that are inherently RHM, the LHM dispersion lacks the light-line branch since their dipolar features are not aligned with the electric and magnetic fields of a right-handed plane-wave solution in free space. Furthermore, it is shown that the spatial width of the LHM is significantly smaller than that of the RHM. Excitation theory is developed, and it is shown that the chain possesses modal and excitatio...

  5. Allergenic proteins of natural rubber latex.

    Science.gov (United States)

    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. The preparation of composite microsphere with hollow core/porous shell structure by self-assembling of latex particles at emulsion droplet interface.

    Science.gov (United States)

    He, Xiao Dong; Ge, Xue Wu; Wang, Mo Zhen; Zhang, Zhi Cheng

    2006-07-15

    A submicrometer-scaled polystyrene/melamine-formaldehyde hollow microsphere composite was prepared by self-assembling of sulfonated polystyrene (SPS) latex particles at the interface of emulsion droplets and then being fixed in place using a hard melamine-formaldehyde (MF) composite layer. For control-released purposes, the influential factors that control the size and uniformity of the packed-droplets and the permeability of the composite shell, including the initial particle location, the hydrophilicity and the size of colloidal templates, the oil phase solvent and reserving time of emulsions after the addition of MF prepolymer, were further studied. Relatively uniform sized particle packed-droplets with an average diameter of 10 microm were obtained. The assembled SPS particles kept ordering and minimal conglutination after the preparation of composite microspheres, which allows of controlling the permeability from the interstices between the particles. Porous-mesh-structured MF composite layer was formed to further control the permeability. The morphology of emulsions and composite microspheres were characterized by optical microscopy, scanning and transmission electron microscopy.

  7. Kinetics of Colloidal Deposition and Release of Polystyrene Latex Particles in the Presence of Adsorbed beta-Lactoglobulin Studied Using a Flow Cell

    Science.gov (United States)

    Joscelyne; Trägårdh

    1997-08-15

    The effect of adsorbed whey protein, beta-lactoglobulin, has been investigated on the attachment of polystyrene latex particles to an indium tin oxide (ITO) surface and the subsequent release in anionic surfactant SDS solution and distilled-deionized water at pH 6.0. Experiments were carried out using a wall-jet flow cell and particle attachment was measured in situ using the technique of evanescent wave microscopy. The deposition rate of particles increased as predicted up to a shear rate of approximately 1000 s-1, for deposition at a diffusion-limited rate. There was a reduction in the rate at higher shear rates indicating a decrease in sticking efficiency. As the shear rate increased, the ITO surface became saturated more quickly due predominantly to blocking of the surface by deposited particles. The presence of adsorbed beta-lactoglobulin on the ITO surface caused a large reduction in the subsequent deposition rate of protein-coated particles. This was due to an increase in electrostatic repulsion. Differences were found in both the extent of removal and in the release (cleaning) kinetics of particles in SDS and in distilled-deionized water for the different particle-protein-ITO surface conditions investigated. Release of particles was also independent of the shear rate. Results were interpreted by considering the roles of protein replacement and elution which occurs in SDS solutions; >90% removal of protein-coated particles from a coated ITO surface was observed in SDS when both processes play a role. This compared to 55% removal in distilled-deionized water where they were considered negligible. Copyright 1997Academic Press

  8. Chiral imprinting of diblock copolymer single-chain particles.

    Science.gov (United States)

    Njikang, Gabriel; Liu, Guojun; Hong, Liangzhi

    2011-06-07

    This Article reports the molecular imprinting of polymer single-chain particles that have a radius ∼3.7 nm. For this, the template L-phenylalanine anilide or L-ΦAA and a diblock copolymer PtBA-b-P(CEMA-r-CA) were used. Here, PtBA denotes poly(tert-butyl acrylate), and P(CEMA-r-CA) denotes a random block consisting of cinnamoyloxyethyl methacrylate (CEMA) and carboxyl-bearing (CA) units. In CHCl(3)/cyclohexane (CHX) with 64 vol % of CHX or at f(CHX) = 64%, a block-selective solvent for PtBA, PtBA-b-P(CEMA-r-CA) formed spherical micelles. The core consisted of the insoluble P(CEMA-r-CA) block and L-ΦAA, which complexed with the CA groups. Pumping slowly this micellar solution into stirred CHCl(3)/(CHX) at f(CHX) = 64% triggered micelle dissociation into single-chain micelles, which comprised presumably a solubilized PtBA tail and a collapsed P(CEMA-r-CA)/L-ΦAA head. Because the solvent reservoir was under constant UV irradiation, the photo-cross-linkable units in the P(CEMA-r-CA) head cross-linked, and the single-chain micelles were converted into cross-linked single-chain micelles or tadpoles. Synchronizing the micelle addition and photoreaction rates allowed the preparation, from this protocol, of essentially pure tadpoles at high final polymer concentrations. Imprinted tadpoles were procured after L-ΦAA was extracted from the tadpole heads. Under optimized conditions, the produced imprinted tadpoles had exceptionally high binding capacity and high selectivity for L-ΦAA. In addition, the rates of L-ΦAA release from and rebinding by the particles were high.

  9. PREAPARATION OF CATIONIC LATEXES OF POLY(STYRENE-CO-BUTYL ACRYLATE) AND THEIR PROPERTIES EVOLUTION IN LATEX DILUTION

    Institute of Scientific and Technical Information of China (English)

    Dong Zou; Xiu-fen Li; Xiao-li Zhu; Xiang-zheng Kong

    2012-01-01

    Cationic latexes were prepared through emulsion copolymerization of styrene (St) and butyl acrylate (BA) with a cationic surfactant,cetyl trimethyl ammonium bromide (CTAB).Latex properties,including particle size,size distribution,ζ potential,surface tension and monomer conversion,were determined for latexes prepared with different CTAB amounts.Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation.Results showed that both particle size and ζpotential were function of polymerization time and latex solids.Parallel emulsion polymerizations with cationic,anionic charged initiator and charge-free initiators were also carried out,the latex properties were determined at different polymerization time.All these results were attentively interpreted based on the mechanisms of emulsion polymerization,surfactant adsorption and latex particle stabilization.

  10. Complex statistics and diffusion in nonlinear disordered particle chains

    Energy Technology Data Exchange (ETDEWEB)

    Antonopoulos, Ch. G., E-mail: chris.antonopoulos@abdn.ac.uk [Institute for Complex Systems and Mathematical Biology (ICSMB), Department of Physics, University of Aberdeen, AB24 3UE Aberdeen (United Kingdom); Bountis, T., E-mail: bountis@math.upatras.gr [Center for Research and Applications of Nonlinear Systems (CRANS), Department of Mathematics, University of Patras, 26500 Patras (Greece); Skokos, Ch., E-mail: haris.skokos@uct.ac.za [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, Cape Town 7701 (South Africa); Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Drossos, L., E-mail: ldrossos@teimes.gr [High Performance Computing Systems Lab (HPCS lab), Department of Computer and Informatics Engineering, Technological Educational Institute of Western Greece, 30300 Antirion (Greece)

    2014-06-15

    We investigate dynamically and statistically diffusive motion in a Klein-Gordon particle chain in the presence of disorder. In particular, we examine a low energy (subdiffusive) and a higher energy (self-trapping) case and verify that subdiffusive spreading is always observed. We then carry out a statistical analysis of the motion, in both cases, in the sense of the Central Limit Theorem and present evidence of different chaos behaviors, for various groups of particles. Integrating the equations of motion for times as long as 10{sup 9}, our probability distribution functions always tend to Gaussians and show that the dynamics does not relax onto a quasi-periodic Kolmogorov-Arnold-Moser torus and that diffusion continues to spread chaotically for arbitrarily long times.

  11. Colloid stable sorbents for cesium removal: preparation and application of latex particles functionalized with transition metals ferrocyanides.

    Science.gov (United States)

    Avramenko, Valentin; Bratskaya, Svetlana; Zheleznov, Veniamin; Sheveleva, Irina; Voitenko, Oleg; Sergienko, Valentin

    2011-02-28

    In this paper we suggest a principally new approach to preparation of colloid stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid stable sorbents toward cesium ions were studied in solutions containing up to 200 g/L of sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.3-1.5 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that made them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed.

  12. Colloid stable sorbents for cesium removal: Preparation and application of latex particles functionalized with transition metals ferrocyanides

    Energy Technology Data Exchange (ETDEWEB)

    Avramenko, Valentin [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Bratskaya, Svetlana, E-mail: sbratska@ich.dvo.ru [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Zheleznov, Veniamin; Sheveleva, Irina [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Voitenko, Oleg [Far Eastern Federal University, Laboratory of Electron Microscopy and Image Processing, 27, Oktyabr' skaya Street, Vladivostok 690950 (Russian Federation); Sergienko, Valentin [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation)

    2011-02-28

    In this paper we suggest a principally new approach to preparation of colloid stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid stable sorbents toward cesium ions were studied in solutions containing up to 200 g/L of sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.3-1.5 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that made them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed.

  13. LATEX for Librarians.

    Science.gov (United States)

    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…

  14. Ethrel-stimulated prolongation of latex flow in the rubber tree (Hevea brasiliensis Muell. Arg.): an Hev b 7-like protein acts as a universal antagonist of rubber particle aggregating factors from lutoids and C-serum.

    Science.gov (United States)

    Shi, Min-Jing; Cai, Fu-Ge; Tian, Wei-Min

    2016-02-01

    Ethrel is the most effective stimuli in prolonging the latex flow that consequently increases yield per tapping. This effect is largely ascribed to the enhanced lutoid stability, which is associated with the decreased release of initiators of rubber particle (RP) aggregation from lutoid bursting. However, the increase in both the bursting index of lutoids and the duration of latex flow after applying ethrel or ethylene gas in high concentrations suggests that a new mechanism needs to be introduced. In this study, a latex allergen Hev b 7-like protein in C-serum was identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS). In vitro analysis showed that the protein acted as a universal antagonist of RP aggregating factors from lutoids and C-serum. Ethrel treatment obviously weakened the effect of C-serum on RP aggregation, which was closely associated with the increase in the level of the Hev b 7-like protein and the decrease in the level of the 37 kDa protein, as revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), western blotting analysis and antibody neutralization. Thus, the increase of the Hev b 7-like protein level or the ratio of the Hev b 7-like protein to the 37 kDa protein in C-serum should be primarily ascribed to the ethrel-stimulated prolongation of latex flow duration.

  15. Event-chain Monte Carlo algorithms for three- and many-particle interactions

    Science.gov (United States)

    Harland, J.; Michel, M.; Kampmann, T. A.; Kierfeld, J.

    2017-02-01

    We generalize the rejection-free event-chain Monte Carlo algorithm from many-particle systems with pairwise interactions to systems with arbitrary three- or many-particle interactions. We introduce generalized lifting probabilities between particles and obtain a general set of equations for lifting probabilities, the solution of which guarantees maximal global balance. We validate the resulting three-particle event-chain Monte Carlo algorithms on three different systems by comparison with conventional local Monte Carlo simulations: i) a test system of three particles with a three-particle interaction that depends on the enclosed triangle area; ii) a hard-needle system in two dimensions, where needle interactions constitute three-particle interactions of the needle end points; iii) a semiflexible polymer chain with a bending energy, which constitutes a three-particle interaction of neighboring chain beads. The examples demonstrate that the generalization to many-particle interactions broadens the applicability of event-chain algorithms considerably.

  16. Study on Soap-free P(MMA-EA-AA/MAA) Latex Particles With Narrow Size Distribution

    Institute of Scientific and Technical Information of China (English)

    K. Kang; C. Y. Kan; Y. Du; D. S. Liu

    2005-01-01

    @@ 1Introduction In the past decades, more and more studies have been focused on the synthesis of monodisperse particles with different diameter by special polymerization technique. In 1980' s, Ugelstad, et al[1] invented two-step swelling method to prepare monodisperse microsphere with large size more than 1 μm. In the following decade, Okubo and his coworkers[2] synthesized monodisperse crosslinked polymer particles above 3 μm using one-step dynamic swelling method. New method has been developed to produce particles more than 50 μm in diameter with a standard deviation of less than 2%[3]. Up to now, most of the monodisperse particles were usually prepared by polymerization of St in the presence of surfactants. In this presentation, sub-micro sized P (MMA-EA-AA/MAA) particles with narrow size distribution were prepared by seeded emulsion polymerization in the absence of any surfactant materials.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 latex-based adhesive significantly increased the strength and water resistance of the resulting wood.

  19. Surface selective binding of nanoclay particles to polyampholyte protein chains

    Science.gov (United States)

    Pawar, Nisha; Bohidar, H. B.

    2009-07-01

    Binding of nanoclay (Laponite) to gelatin-A and gelatin-B (both polyampholytes) molecules was investigated at room temperature (25 °C) both experimentally and theoretically. The stoichiometric binding ratio between gelatin and Laponite was found to be strongly dependent on the solution ionic strength. Large soluble complexes were formed at higher ionic strengths of the solution, a result supported by data obtained from light scattering, viscosity, and zeta potential measurements. The binding problem was theoretically modeled by choosing a suitable two-body screened Coulomb potential, U(R+)=(q-/2ɛ)[(Q-/R-)e-kR--(Q+/R+)e-kR+], where the protein dipole has charges Q+ and Q_ that are located at distances R+ and R_ from the point Laponite charge q- and the dispersion liquid has dielectric constant (ɛ). U(R+) accounted for electrostatic interactions between a dipole (protein molecule) and an effective charge (Laponite particle) located at an angular position θ. Gelatin-A and Laponite association was facilitated by a strong attractive interaction potential that led to preferential binding of the biopolymer chains to negatively charged face of Laponite particles. In the case of gelatin-B selective surf ace patch binding dominated the process where the positively charged rim and negatively charged face of the particles were selectively bound to the oppositely charged segments of the biopolymer. The equilibrium separation (Re) between the protein and nanoclay particle revealed monovalent salt concentration dependence given by Re˜[NaCl]α where α =0.6±0.2 for gelatin-A and α =0.4±0.2 for gelatin-B systems. The equilibrium separations were ≈30% less compared to the gelatin-A system implying preferential short-range ordering of the gelatin-B-nanoclay pair in the solvent.

  20. Drying of latex films and coatings: Reconsidering the fundamental mechanisms

    DEFF Research Database (Denmark)

    Kiil, Søren

    2006-01-01

    The two existing theories describing drying of latex films or coatings are reconsidered. Subsequently, a novel mathematical drying model is presented, the simulations of which can match and explain experimental drying rate data of two previous investigations with latex films. In contrast...... to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase......), latex particle size (500-600 nm), initial polymer volume concentration (19-47 vol.%), and molecular weight of latex polymer (not quantified). Simulations also demonstrate that the transition from a constant to a falling drying rate in all cases takes place when the polymer volume concentration...

  1. Mosquito larvicidal and silver nanoparticles synthesis potential of plant latex

    OpenAIRE

    H.P. Borase; C.D. Patil; R.B. Salunkhe; C.P. Narkhede; R.K. Suryawanshi; Salunke, B. K.; PATIL S. V

    2014-01-01

    Silver nanoparticles (AgNPs) were synthesized from the latex of the medicinally important plants Euphorbia milii, Euphorbia hirta, Ficus racemosa and Jatropha curcas. Synthesized AgNPs were characterized by UV-Vis spectrophotometry, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, Fourier transformed infrared spectroscopy, particle size, and zeta potential analysis. Potency of latex and latex-synthesized AgNPs was evaluated against the 2nd and 4th instar larv...

  2. Latex Allergy: A Prevention Guide

    Science.gov (United States)

    ... Topics Publications and Products Programs Contact NIOSH Latex Allergy A Prevention Guide Recommend on Facebook Tweet Share ... proteins that cause allergic reactions. What is latex allergy? Latex allergy is a reaction to certain proteins ...

  3. Managing latex allergies at home

    Science.gov (United States)

    ... 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- ...

  4. Latex allergies - for hospital patients

    Science.gov (United States)

    ... proteins that are in latex. These foods include bananas, avocado, and chestnuts. Foods that are less strongly ... Asthma and Immunology. Latex Cross-reactive Foods Fact Sheet. Updated October 8, 2015. latexallergyresources.org/latex-cross- ...

  5. MORPHOLOGICAL OBSERVATION OF SINGLE-CHAIN POLY(METHYL METHACRYLATE) PARTICLES

    Institute of Scientific and Technical Information of China (English)

    NI Ming; CHEN Liusheng; JIA Shijun; JIN Xigao; GE Shouren; Atsushi TAKAHARA; Tisato KAJIYAMA

    1997-01-01

    Tapping mode atomic force microscope has been applied to observe single-chain PMMA particles which were stored for six months at room temperature after sprayed from very dilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodisperse PMMA standards of molecular weights ranging from 7.90 × 104 to 1.3 × 106 were used to investigate the effect of molecular weight on the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight was found to be identical in spite of different solvents used for solution spraying. Molecular weight dependence of the particle dimension was also found. The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared to the values estimated from molecular weight and density.

  6. PREPARATION AND PROPERTIES OF SILICONE-ACRYLATE COPOLYMER LATEX

    Institute of Scientific and Technical Information of China (English)

    Mu-jie Yang; Wei Zhang

    2004-01-01

    Silicone-acrylate copolymer latex was prepared through three different polymerization processes, i.e., the batch process, preemulsified monomer addition and the monomer addition process. The results revealed that the monomer addition process is a desirable approach to produce narrow particle size distribution latex with higher polymerization conversion and less amount of coagulum. The effect of silicone content on the glossiness and water absorption of latex film was investigated and the results showed that the glossiness of latex film is improved up to a silicone content of 10% of total monomers, but becomes impaired thereafter, whereas water absorption is reduced accordingly.

  7. Latex in the Hospital Environment

    Science.gov (United States)

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

  8. Occupational allergies caused by latex.

    Science.gov (United States)

    Ahmed, Debra D Fett; Sobczak, Steven C; Yunginger, John W

    2003-05-01

    Allergy to natural rubber latex is an important cause of occupational allergy in healthcare workers. Disposable medical gloves are the major reservoir of latex allergens, particularly powdered gloves, in healthcare delivery settings. Diagnosis of latex allergy requires a history of exacerbation of cutaneous, respiratory, ocular, or systemic signs and symptoms after exposure to natural rubber latex products; and evidence of sensitization by patch testing, skin testing, measurement of latex-specific IgE antibodies, or challenge testing. Optimal management of latex allergy involves education concerning cross-reacting allergens, reduction of cutaneous or mucosal contact with dipped rubber products, and minimization of exposure to latex aeroallergens in work environments.

  9. 功能化PDMS/PMMA核壳乳胶粒子的制备与表征%Preparation and characterization of functional PDMS / PMMA core-shell latex particles

    Institute of Scientific and Technical Information of China (English)

    王权; 刘喜军; 伊海楠

    2012-01-01

    A novel latex particles of polysiloxane/polymethylmethacrylate (PDMS/PMMA) having core-shell structure was successfully synthesized by the pre-emulsion semi-continuous seeded emulsion polymerization. Through the introduction of functional monomer ITA, MAH or GMA to realize the function of core-shell latex particles.Which were characterized by the laser particle size analyzer. Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM).%采用预乳化-半连续种子乳液聚合工艺合成了聚硅氧烷,聚甲基丙烯酸甲酯(PDMS/PMMA)核壳乳胶粒子,通过引入功能单体ITA、MAH或GMA实现核壳乳胶粒子的功能化。采用激光粒度分析仪、傅立叶变换红外光谱仪(FTIR)和透射电子显微镜(TEM)等手段对核壳乳胶粒子进行了表征。

  10. Application of Latex particles in detecting alpha- fetoprotein (AFP)%乳胶粒子法检测甲胎蛋白的应用

    Institute of Scientific and Technical Information of China (English)

    陈浩全; 曾嫚妮

    2012-01-01

    Objective:To evaluate the application value of Latex method in detection of alpha - fetoprotein ( AFP). Methods:Repetitive determination tests within and between batches were done on serum specimens, then the determination results were compared and analyzed by Latex method and electrochemiluminescence assay. Results; The results had no significant difference between Latex method and electrochemiluminescence assay, the recoveries were 95.5% for Latex method and 96.7% for electrochemiluminescence assay. Conclusion; Though electrochemiluminescence assay had high sensitivity and precision, it was not suitable for the wide use due to its high cost in instrument and reagent. Latex method had good correlation with electrochemiluminescence assay, which can be applied widely for its rapidness, stable results and low cost.%目的:评价Latex法检测甲胎蛋白(AFP)的临床应用价值.方法:对血清标本做批内批间重复性测定试验及Latex法与电化学发光法进行对比测定.结果:Latex法与电化学发光法检测AFP结果无显著差异,Latex法与电化学发光法平均回收率分别为95.5%和96.7%.结论:电化学发光法灵敏度、精密度高,但其仪器、试剂价格高,不适于全面推广;Latex法与电化学发光法检测AFP结果无显著差异,相关性好,快速、结果稳定,试剂便宜在全自动生化仪上检测,可广泛应用.

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

    Science.gov (United States)

    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.

  12. Latex migration in battery slurries during drying.

    Science.gov (United States)

    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.

  13. Latex samples for RAMSES electrophoresis experiment on IML 2

    Science.gov (United States)

    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.

  14. Latex allergy (image)

    Science.gov (United States)

    ... dermatitis, or in a more serious whole body reaction, anaphylaxis. The term "dermatitis" describes an inflammatory response of the skin, caused by contact with allergens or irritants such as the latex ...

  15. Effect of cationic monomer on properties of fluorinated acrylate latex

    Institute of Scientific and Technical Information of China (English)

    Li Jun Chen

    2012-01-01

    Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers.The resultant latex and its film were characterized with dynamic light scattering detector and contact angle meter.Influences of amount of DMDAAC on the properties of resultant latex and its film were investigated in detail.Results show that the particle size of the latex has the minimum value and the zeta potential of the latex is increased when the amount of DMDAAC is increased.In addition,the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%.However,the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%.The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%.Nevertheless,the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 25%.

  16. Particle Markov Chain Monte Carlo Techniques of Unobserved Component Time Series Models Using Ox

    DEFF Research Database (Denmark)

    Nonejad, Nima

    This paper details Particle Markov chain Monte Carlo techniques for analysis of unobserved component time series models using several economic data sets. PMCMC combines the particle filter with the Metropolis-Hastings algorithm. Overall PMCMC provides a very compelling, computationally fast...

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

    Science.gov (United States)

    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...

  18. Research on Demand Prediction of Fresh Food Supply Chain Based on Improved Particle Swarm Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    He Wang

    2015-04-01

    Full Text Available Demand prediction of supply chain is an important content and the first premise in supply management of different enterprises and has become one of the difficulties and hot research fields for the researchers related. The paper takes fresh food demand prediction for example and presents a new algorithm for predicting demand of fresh food supply chain. First, the working principle and the root causes of the defects of particle swarm optimization algorithm are analyzed in the study; Second, the study designs a new cloud particle swarm optimization algorithm to guarantee the effectiveness of particles in later searching phase and redesigns its cloud global optimization searching method and crossover operation; Finally, a certain fresh food supply chain is taken for example to illustrate the validity and feasibility of the improved algorithm and the experimental results show that the improved algorithm can improve prediction accuracy and calculation efficiency when used for demand prediction of fresh food supply chain.

  19. Aqueous Tape Casting Process with Styrene-acrylic Latex Binder

    Institute of Scientific and Technical Information of China (English)

    CUI Xue-min; OUYANG Shi-xi; HUANG Yong; YU Zhi-yong; ZHAO Shi-ke; WANG Chang-an

    2004-01-01

    A commercial styrene-acrylic latex binder has been investigated as a good binder for aqueous Al2O3 suspensions tape-casting process. This paper focuses on the forming film mechanism of latex binder, the rheological behaviors of the suspensions, physical properties of green tapes and drying process of aqueous slurries with latex binder system. The drying process of the alumina suspensions is shown to follow a two-stage mechanism (the first stage: evaporation controlled process; and the second stage: diffusion controlled process). During the drying stage of the suspensions, the compressive force presses the latex particles and makes them be distorted, which results in cross-linking structure in contacted latex particles of the solidified tapes.A smooth-surface and high-strength green tape was fabricated by aqueous tape casting with latex binder system. The results from the SEM images of the crossing section microstructure of green tapes show that the latex is a very suitable binder for aqueous tape casting.

  20. Preparation and characterization of PDMS/PMMA core-shell latex particles having functional group in surface layer%表层功能化PDMS/PMMA核壳乳胶粒子的制备与表征

    Institute of Scientific and Technical Information of China (English)

    张国青; 刘喜军

    2014-01-01

    In this paper, the polydimethyl siloxane/polymethyl methacrylate(PDMS/PMMA)core-shell latex particles (-320 nm)respectively with itaconic acid(ITA),maleic anhydride(MAH)and glycidyl methacrylate(GMA) as functional monomer in surface layer were successfully synthesized employing pre-emulsification semi-continuous process by seeded emulsion polymerization method. Octamethyl cyclotetrasiloxane(D 4 )and Tetravinyl tetramethyl cyelotetrasiloxane as the main monomer were compounded to form PDMS core latex particles with methyl triethoxysilane(MTES)as cross-linking agent. The effects of the reaction time, surfactant and catalyst concentration, and the ratio of D 4 and VD 4 on the polymerization system were studied, and the optimal synthesizing process of PDMS core latex particles was defined.By laser particle size analyzer, Fourier transform infrared spectrometer and transmission electron microscopy analysis showed that the core monomer conversion was nearly 85%and PDMS latex particle size was at about 290 nm when the reaction time was 10 h,surfactant concentration was 5.3%, catalyst concentration was 5.3%,and D4∶VD4=4∶1.%分别以衣康酸(ITA)、马来酸酐(MAH)和甲基丙烯酸缩水甘油酯(GMA)为功能单体,采用预乳化半连续工艺通过种子乳液聚合方法成功合成了表层功能化的聚二甲基硅氧烷/聚甲基丙烯酸甲酯(PDMS/PMMA)核壳乳胶粒子(~320 nm)。PDMS核乳胶粒子以八甲基环四硅氧烷(D 4)和四甲基四乙烯基环四硅氧烷(VD 4)为单体、甲基三乙氧基硅烷(MTES)为交联剂构建而成,实验研究了反应时间、乳化剂和催化剂用量、单体D 4与VD 4比例对聚合体系的影响,并确定了PDMS核乳胶粒子合成最佳工艺。通过激光粒度分析仪、傅里叶变换红外光谱仪、透射电子显微镜等分析表明:当反应时间为10 h、乳化剂用量为核单体总量的5.3%、催化剂用量为核单体总量的5.3%

  1. Mosquito larvicidal and silver nanoparticles synthesis potential of plant latex

    Directory of Open Access Journals (Sweden)

    H.P. Borase

    2014-08-01

    Full Text Available Silver nanoparticles (AgNPs were synthesized from the latex of the medicinally important plants Euphorbia milii, Euphorbia hirta, Ficus racemosa and Jatropha curcas. Synthesized AgNPs were characterized by UV-Vis spectrophotometry, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, Fourier transformed infrared spectroscopy, particle size, and zeta potential analysis. Potency of latex and latex-synthesized AgNPs was evaluated against the 2nd and 4th instar larvae of Aedes aegypti and Anopheles stephensi. The lowest lethal concentration 50 (LC50 value among the different types of plant latex studied was observed for latex of E. milii (281.28±23.30 and 178.97±37.82 ppm, respectively against 2nd instar larvae of Ae. aegypti and An. stephensi. E. milii latex-synthesised AgNPs showed a high reduction in LC50 compared with its latex; i.e., 8.76±0.46 and 8.67±0.47 ppm, respectively, for 2nd instars of Ae. aegypti and An. stephensi. LC50 values of AgNPs synthesized using the latex of E. hirta, F. racemosa and J. curcas were lower than those of the latex of the respective plants; i.e., 10.77±0.53, 9.81±0.52, 12.06±0.60 and 8.79±0.51, 9.83±0.52, 9.60±0.51 ppm, respectively, for 2nd instars of An. stephensi and Ae. aegypti. Similarly, as compared with the plant latex, lower LC50 values were reported for latex-synthesized AgNPs against 4th instars of Ae. aegypt and An. stephensi. Results showed that all the types of plant latex investigated have the potential to convert silver nitrate into AgNPs showing a spectrum of potent mosquito larvicidal effects, indicating the possibility of further exploration of the bioefficacy of latex and latex-synthesized AgNPs against vectors of public health concerns.

  2. Latex and friends

    CERN Document Server

    Dongen, M R C van

    2012-01-01

    LaTeX is a free, automated state-of-the-art typesetting system. This book teaches all the ins and outs of LaTeX which are needed to write an article, report, thesis, or book. The book teaches by example, giving many worked out examples showing input and output side by side. The book presents the most recent techniques for presenting data plots, complex graphics, and computer presentations, but does not require previous knowledge. However, it is also a reference for the more seasoned user, with pointers to modern techniques and packages. Recurring themes in the book are consistent and effective

  3. Heat conduction in a chain of colliding particles with a stiff repulsive potential

    Science.gov (United States)

    Gendelman, Oleg V.; Savin, Alexander V.

    2016-11-01

    One-dimensional billiards, i.e., a chain of colliding particles with equal masses, is a well-known example of a completely integrable system. Billiards with different particle masses is generically not integrable, but it still exhibits divergence of a heat conduction coefficient (HCC) in the thermodynamic limit. Traditional billiards models imply instantaneous (zero-time) collisions between the particles. We relax this condition of instantaneous impact and consider heat transport in a chain of stiff colliding particles with the power-law potential of the nearest-neighbor interaction. The instantaneous collisions correspond to the limit of infinite power in the interaction potential; for finite powers, the interactions take nonzero time. This modification of the model leads to a profound physical consequence—the probability of multiple (in particular triple) -particle collisions becomes nonzero. Contrary to the integrable billiards of equal particles, the modified model exhibits saturation of the heat conduction coefficient for a large system size. Moreover, the identification of scattering events with triple-particle collisions leads to a simple definition of the characteristic mean free path and a kinetic description of heat transport. This approach allows us to predict both the temperature and density dependencies for the HCC limit values. The latter dependence is quite counterintuitive—the HCC is inversely proportional to the particle density in the chain. Both predictions are confirmed by direct numerical simulations.

  4. Effect of C8mimPF6 on miniemulsion polymerization for application in new latex coating products.

    Science.gov (United States)

    Hu, Binjie; Kong, Yiyang; Zheng, Rongmeihui; Dong, Jie; Choy, Kwang-Leong; Zhao, Huanhuan

    2016-08-15

    C8mimPF6, as a type of room temperature ionic liquid (RTIL) with non-volatility and a low melting point, may replace conventional coalescing agents in latex coatings, thus preventing volatile organic compound (VOC) emissions caused by coalescing agents. In this study, systematic investigations on the effect of various factors including initiator type, initiator concentration, temperature and C8mimPF6 concentration on the conversion of latex and droplet/particle size of a miniemulsion during polymerization have been conducted. The presence of C8mimPF6 has shown to have a marked effect on the reaction rate. Such an effect strongly depends on the type of initiator being used. For polymerization initiated by 2,2-azobis (isobutyronitrile) (AIBN), C8mimPF6 had a promoting effect on the reaction rate at low concentrations, but this effect might be reversed upon certain C8mimPF6 concentrations, e.g. 10 wt%. While initiated by H2O2/Vc, this promoting effect faded even at low C8mimPF6 concentrations. The different limiting factors, which determine the reaction rate with different types of initiator, may contribute to the results. For reactions initiated by hydrophobic AIBN, the reaction was dominated by kinetics. The presence of C8mimPF6 may cause an enhanced chain propagation rate and reduced chain termination rate, which may further contribute to the increase in reaction rate at lower concentrations of C8mimPF6. With hydrophilic H2O2/Vc, the resistance for the transfer of radicals into a droplet/particle might be increased significantly with increasing C8mimPF6 concentration due to a tighter interfacial structure at lower concentrations of C8mimPF6. Thus, such transfer of radicals may become a limiting step whilst the presence of C8mimPF6 increases the transfer resistance on radicals resulting in a decrease in reaction rate. The reaction temperature, which is related to the decomposition temperature of the initiator being used, was another factor affecting the conversion

  5. Latex medical gloves

    DEFF Research Database (Denmark)

    Palosuo, Timo; Antoniadou, Irini; Gottrup, Finn

    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...

  6. Pose control of the chain composed of magnetic particles using external uniform and gradient magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J. F., E-mail: zhoujianfeng@njtech.edu.cn; Shao, C. L.; Gu, B. Q. [Nanjing Tech University, School of Mechanical and Power Engineering (China)

    2016-01-15

    Magnetic particles (MPs) are known to respond to a magnetic field and can be moved by magnetic force, which make them good carriers in bioengineering and pharmaceutical engineering. In this paper, a pose control method for the straight chain composed of MPs is proposed, and the chain with one pose can be moved to another position with another pose using alternately employed uniform and gradient magnetic fields. Based on computer simulations, it is revealed that in the uniform magnetic field, the MPs form a straight chain with the same separation space along the field lines, and once the uniform magnetic field rotates, the chain also rotates with the field. In the gradient magnetic field, the MPs move toward the higher field so that the translation of the chain can be realized. The simulation results indicate that while the uniform magnetic field is rotating, there exists certain hysteresis between the chain and the field, and the chain is not straight anymore. So the uniform magnetic field should rest at the target angle for a period to make the chain fully relax to be straight. For nanoMP, its magnetic moment directly determines the gradient magnetic force which is much smaller than the dipole–dipole force among MPs. Therefore, the translation of the chain is much more time-consuming than rotation. To enlarge the translational velocity, it is suggested to increase the size of MPs or the magnetic field gradient.

  7. Dynamics of particle sedimentation in viscoelastic fluids: A numerical study on particle chain in two-dimensional narrow channel

    CERN Document Server

    Pan, Tsorng-Whay

    2016-01-01

    In this article we present a numerical method for simulating the sedimentation of circular particles in two-dimensional channel filled with a viscoelastic fluid of FENE-CR type, which is generalized from a domain/distributed Lagrange multiplier method with a factorization approach for Oldroyd-B fluids developed in [J. Non-Newtonian Fluid Mech. 156 (2009) 95]. Numerical results suggest that the polymer extension limit L for the FENE-CR fluid has no effect on the final formation of vertical chain for the cases of two disks and three disks in two-dimensional narrow channel, at least for the values of L considered in this article; but the intermediate dynamics of particle interaction before having a vertical chain can be different for the smaller values of L when increasing the relaxation time. For the cases of six particles sedimenting in FENE-CR type viscoelastic fluid, the formation of chain of 4 to 6 disks does depend on the polymer extension limit L. For the smaller values of L, FENE-CR type viscoelastic flu...

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

    Science.gov (United States)

    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.

  9. Preparation of hollow TiO2 nanoparticles through TiO2 deposition on polystyrene latex particles and characterizations of their structure and photocatalytic activity

    Science.gov (United States)

    2012-01-01

    In a mixed solvent of water and ethanol, polystyrene/titanium dioxide (PSt/TiO2) composite particles of core-shell structure were prepared by hydrolysis of tetrabutyl titanate in the presence of cationic PSt particles or anionic PSt particles surface-treated using γ-aminopropyl triethoxysilane. Hollow TiO2 particles were obtained through calcination of the PSt/TiO2 core-shell particles to burn off the PSt core or through dissolution of the core by tetrahydrofuran (THF). An alternative process constituted of preheating the PSt/TiO2 particles at 200°C to allow partial crystallization followed by calcination or PSt dissolution by THF. The outcome TiO2 particles thus prepared were examined by TEM, and hollow TiO2 particles were observed. The crystalline phase structure and phase transformation were characterized, which revealed that preheating before the removal of the PSt core was useful to achieve the desired hollow TiO2 particles, and the calcination process was beneficial to the formation of anatase and rutile structures. The tests of TiO2 particles as catalyst in the photodegradation of Rhodamine B demonstrated that a much higher catalytic activity was observed with the TiO2 hollow particles prepared through calcination combined with preheating. PMID:23176612

  10. Consistent model reduction of polymer chains in solution in dissipative particle dynamics: Model description

    KAUST Repository

    Moreno Chaparro, Nicolas

    2015-06-30

    We introduce a framework for model reduction of polymer chain models for dissipative particle dynamics (DPD) simulations, where the properties governing the phase equilibria such as the characteristic size of the chain, compressibility, density, and temperature are preserved. The proposed methodology reduces the number of degrees of freedom required in traditional DPD representations to model equilibrium properties of systems with complex molecules (e.g., linear polymers). Based on geometrical considerations we explicitly account for the correlation between beads in fine-grained DPD models and consistently represent the effect of these correlations in a reduced model, in a practical and simple fashion via power laws and the consistent scaling of the simulation parameters. In order to satisfy the geometrical constraints in the reduced model we introduce bond-angle potentials that account for the changes in the chain free energy after the model reduction. Following this coarse-graining process we represent high molecular weight DPD chains (i.e., ≥200≥200 beads per chain) with a significant reduction in the number of particles required (i.e., ≥20≥20 times the original system). We show that our methodology has potential applications modeling systems of high molecular weight molecules at large scales, such as diblock copolymer and DNA.

  11. Capsular Serotyping of Streptococcus pneumoniae by latex agglutination.

    Science.gov (United States)

    Porter, Barbara D; Ortika, Belinda D; Satzke, Catherine

    2014-09-25

    Latex agglutination reagents are widely used in microbial diagnosis, identification and serotyping. Streptococcus pneumoniae (the pneumococcus) is a major cause of morbidity and mortality world-wide. Current vaccines target the pneumococcal capsule, and there are over 90 capsular serotypes. Serotyping pneumococcal isolates is therefore important for assessing the impact of vaccination programs and for epidemiological purposes. The World Health Organization has recommended latex agglutination as an alternative method to the 'gold standard' Quellung test for serotyping pneumococci. Latex agglutination is a relatively simple, quick and inexpensive method; and is therefore suitable for resource-poor settings as well as laboratories with high-volume workloads. Latex agglutination reagents can be prepared in-house utilizing commercially-sourced antibodies that are passively attached to latex particles. This manuscript describes a method of production and quality control of latex agglutination reagents, and details a sequential testing approach which is time- and cost-effective. This method of production and quality control may also be suitable for other testing purposes.

  12. Neutrino World Chain in Framework of Skeleton Conception of Particle Dynamics

    Science.gov (United States)

    Rylov, Yuri A.

    2012-09-01

    One considers a free neutral particle whose world chain is a spacelike helix with timelike axis. Such world chain appears to be possible in some discrete space-time geometry. Radius of the helix may be macroscopic. This fact agrees with the results of the OPERA experiment, where superluminal velocity of a neutrino has been discovered. The helical world chain can be approximated by a world tube of macroscopic radius. Discovery of the neutrino superluminal velocity is an end effect of the thick world tube, but not the mean superluminal velocity of neutrino. The discrete space-time geometry has no definite metric dimension. Mathematical technique of linear vector space (technique of differential geometry) cannot be used in the discrete space-time geometry. Coordinateless description of the discrete space-time geometry is used.

  13. Flocculation of fine fluorite particles with Corynebacterium xerosis and commercial long chain polymers

    Directory of Open Access Journals (Sweden)

    Rigo Lisandra N.

    2002-01-01

    Full Text Available This work aimed to study, comparatively, the flocculation of fluorite particles with Corynebacterium xerosis cells and three commercial long chain polymers. Best flocculation results were obtained with cells of C. xerosis and with an anionic polyacrylamide. Both were effective in solids removal and water clarification, although flocculation with C. xerosis cells requires a higher dosage of reagent per mass unit of processed ore.

  14. Development of a CMOS Oscillator Chain for Particle Detection based on SOI technology

    Energy Technology Data Exchange (ETDEWEB)

    Coulie-Castellani, K.; Ben Krit, S.; Rahajandraibe, W.; Aziza, H.; Portal, J-M. [Aix Marseille Universite, CNRS, Universite de Toulon, IM2NP UMR 7334, Marseille (France); Micolau, G. [Universite d' Avignon, UMR 1114 EMMAH, INRA-UAPV, Avignon (France)

    2015-07-01

    A new development of an oscillator concept, dedicated to the detection and tracking of particles with low fluxes, is presented. The solution is based on an indirect detection of the current generated at the input of the detection chain, through a Voltage Controlled Oscillator (VCO) response. The very first solution was proposed using bulk technology. This new development is based on SOI technology what makes it tolerant to radiations. (authors)

  15. STUDY ON SYNTHESIS OF SELF CORSS LINKED POLYSTYRENE LATEX MICROSPHERES

    Institute of Scientific and Technical Information of China (English)

    DaiLizong; ZouYousi; 等

    1997-01-01

    Emulsifier-free emulsion polymerization of styrene in the presence of β-hydroxy propyl acrylate was studied.The emulsifier-free self cross linked polystyrene latex microspheres was obtained.Monomer conversion is higher than 90% when [St],[β-HPA],[KPS] is 2.66,0.228,and 5.8×10-3mol/L respectively under 80℃ for 5h.The mono-dispersed latex particle diameter and colloidal particle concentration were given as D=0.23um,N=3.13×1013/cm3 by TEM analyse,The factors of influencing latex stability were discussed.Thecopolymer was characterized by IR and dissolution experiment.The apparent activation energy of polymerization and polymerization rate constant were obtained to be 78.7KJ/mol and 514.4/mol.s respectively.

  16. Preparation of MMA-BA-DMAEMA Nanosized Latex

    Institute of Scientific and Technical Information of China (English)

    Yu Yang LIU; Mu Jie YANG

    2003-01-01

    The terpolymer latex of methyl methacrylate (MMA)/butyl acrylate (BA)/ dimethyl aminoethyl methacrylate (DMAEMA) with diameter of less than 100 nm was prepared by seeding semi-continuous emulsion copolymerization using APS (ammonium persulfate) / TMEDA (N,N,N, N-tetramethylethylenediamine) as the redox initiators and SDS (sodium dodecylsulfate) and OP (P-octylpolyethylene glycol phenylether) as co-emulsifiers. The factors that influenced the process stability of the copolymerization and the particle size of the latex were investigated. The addition of aqueous ammonia as coagulation inhibitor provided better process stability of the copoly- merization. The addition of acetic acid as the acidification agent caused a remarkable reduction of the latex particle size.

  17. Antimicrobial activity of latex silver nanoparticles using Calotropis procera

    Institute of Scientific and Technical Information of China (English)

    Nadia; Hussein; Mohamed; Mady; Ahmed; Ismail; Wael; Moustfa; Abdel-Mageed; Ahmed; Abdelfattah; Mohamed; Shoreit

    2014-01-01

    Objective:To synthesize silver nanoparticles(AgNPs) by green methods using scrum latex of Calotropis procera at 80 ℃ and evaluate them against bacteria,dermatophytes and phytopathogenic fungi comparing with the activity of untreated latex.Methods:The synthesis of AgNPs was performed by mixing 3%latex scrum extract with the same volume of silver nitrate(2 mmol/L) solution in round flask and heating in water bath at80 ℃.Characterization of silver particles were determined using UV-vis spectrophotometer,transmission electron microscopy(TEM),X-ray diffraction and Fourier transform infrared spectroscopy.The antimicrobial activity of the green synthesized AgNPs was determined against bacteria,dermatophytes and phytopathogenic fungi and compared to the crude untreated latex by agar-well diffusion methods.Results:Biosynthesis of latex silver nanoparticles was successfully obtained by green method.The formation of AgNPs has been confirmed by UV-vis,TEM microscopy.X-ray diffraction and Fourier transform infrared spectroscopy.TEM analysis showed that synthesized AgNPs are highly stable spherical shaped particles,well dispersed with a diameter ranged from 4 nm up to 25 nm and an average size of 12.33 nm.AgNPs showed strong antibacterial activity against Gram-negative bacteria(Escherichia coli,Pseudomonas aeruginosa and Serratia sp.) and antifungal activity against Trichophyton rubrum,Candida albicans and Aspergillus terreus.Conclusions:It can be concluded that serum latex of Calotropis pmcera was found to display strong potential for the synthesis of AgNPs as antimicrobial agents through rapid reduction of silver ions(Ag~+ to Ag~0).The green synthesized AgNPs were found to show higher antimicrobial efficacy than crude latex.

  18. Antimicrobial activity of latex silver nanoparticles using Calotropis procera

    Institute of Scientific and Technical Information of China (English)

    Nadia Hussein Mohamed; Mady Ahmed Ismail; Wael Moustfa Abdel-Mageed

    2014-01-01

    Objective: To synthesize silver nanoparticles (AgNPs) by green methods using serum latex of Calotropis procera at 80 °C and evaluate them against bacteria, dermatophytes and phytopathogenic fungi comparing with the activity of untreated latex.Methods:The synthesis of AgNPs was performed by mixing 3% latex serum extract with the same volume of silver nitrate (2 mmol/L) solution in round flask and heating in water bath at 80 °C. Characterization of silver particles were determined using UV-vis spectrophotometer, transmission electron microscopy (TEM), X-ray diffraction and Fourier transform infrared spectroscopy. The antimicrobial activity of the green synthesized AgNPs was determined against bacteria, dermatophytes and phytopathogenic fungi and compared to the crude untreated latex by agar-well diffusion methods.Results:Biosynthesis of latex silver nanoparticles was successfully obtained by green method. The formation of AgNPs has been confirmed by UV-vis, TEM microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. TEM analysis showed that synthesized AgNPs are highly stable spherical shaped particles, well dispersed with a diameter ranged from 4 nm up to 25 nm and an average size of 12.33 nm. AgNPs showed strong antibacterial activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Serratia sp.) and antifungal activity against Trichophyton rubrum, Candida albicans and Aspergillus terreus.Conclusions:It can be concluded that serum latex of Calotropis procera was found to display strong potential for the synthesis of AgNPs as antimicrobial agents through rapid reduction of silver ions (Ag+ to Ag0). The green synthesized AgNPs were found to show higher antimicrobial efficacy than crude latex.

  19. Reduction of cytotoxicity of natural rubber latex film by coating with PMMA-chitosan nanoparticles.

    Science.gov (United States)

    Kanjanathaworn, Nuttakun; Polpanich, Duangporn; Jangpatarapongsa, Kulachart; Tangboriboonrat, Pramuan

    2013-08-14

    Poly(methyl methacrylate) (PMMA) latex stabilized by chitosan (CS) oligomer was synthesized via the miniemulsion polymerization. By using 1% CS solution (in 0.1M acetic acid), the spherical PMMA-CS particles with an average size of 380 nm were obtained. The positive zeta potentials at pH 2-7 confirmed the presence of CS as the outermost layer of the latex particles. Therefore, these particles directly interacted with the indigenous non-rubbers at the surface of sulphur prevulcanized natural rubber (SPNR) film. The deposition of PMMA-CS particles caused an increase in surface roughness of the coated SPNR film as a function of latex concentration and immersion time. The simple coating of the rubber substrate with PMMA-CS particles effectively reduced the in vitro cytotoxicity on L-929 cells. This study would be, therefore, helpful for development of latex gloves designed for hypersensitive users.

  20. Existence and Modulation of Uniform Sliding States in Driven and Overdamped Particle Chains

    Science.gov (United States)

    Qin, Wen-Xin

    2012-04-01

    In this paper we are mainly concerned with existence and modulation of uniform sliding states for particle chains with damping γ and external driving force F. If the on-site potential vanishes, then for each F > 0 there exist trivial uniform sliding states x n ( t) = n ω + ν t + α for which the particles are uniformly spaced with spacing ω > 0, the sliding velocity of each particle is ν = F/ γ, and the phase α is arbitrary. If the particle chain with convex interaction potential is placed in a periodic on-site potential, we show under some conditions the existence of modulated uniform sliding states of the form x_n(t)=nω+ν t+α+u(nω+ν t+α), where the modulation function u is periodic and unique up to phase. The conditions are that the system is overdamped and the driving force F exceeds some critical value F d ( ω) ≥ 0 depending on mean spacing ω. If {Fin [0,F_d(ω)]} , the system possesses a set of rotationally ordered equilibrium states for irrational ω, which can be described by a non-decreasing hull function, just as the case γ = F = 0, where Aubry-Mather theory applies to ground states. Meanwhile, we prove that F d ( ω) = 0, which was argued physically much earlier, if the hull function of ground states with irrational rotation number ω for F = 0 is continuous.

  1. Heat conduction in a chain of dissociating particles: Effect of dimensionality

    Science.gov (United States)

    Zolotarevskiy, V.; Savin, A. V.; Gendelman, O. V.

    2015-03-01

    The paper considers heat conduction in a model chain of composite particles with hard core and elastic external shell. Such model mimics three main features of realistic interatomic potentials—hard repulsive core, quasilinear behavior in a ground state, and possibility of dissociation. It has become clear recently that this latter feature has crucial effect on convergence of the heat conduction coefficient in thermodynamic limit. We demonstrate that in one-dimensional chain of elastic particles with hard core the heat conduction coefficient also converges, as one could expect. Then we explore effect of dimensionality on the heat transport in this model. For this sake, longitudinal and transversal motions of the particles are allowed in a long narrow channel. With varying width of the channel, we observe sharp transition from "one-dimensional" to "two-dimensional" behavior. Namely, the heat conduction coefficient drops by about order of magnitude for relatively small widening of the channel. This transition is not unique for the considered system. Similar phenomenon of transition to quasi-1D behavior with growth of aspect ratio of the channel is observed also in a gas of densely packed hard (billiard) particles, both for two- and three-dimensional cases. It is the case despite the fact that the character of transition in these two systems is not similar, due to different convergence properties of the heat conductivity. In the billiard model, the divergence pattern of the heat conduction coefficient smoothly changes from logarithmic to power-like law with increase of the length.

  2. Near-Infrared Super Resolution Imaging with Metallic Nanoshell Particle Chain Array

    CERN Document Server

    Kong, Weijie; Cao, Penfei; Cheng, Lin; Gong, Li; Zhao, Xining; Yang, Lili

    2012-01-01

    We propose a near-infrared super resolution imaging system without a lens or a mirror but with an array of metallic nanoshell particle chain. The imaging array can plasmonically transfer the near-field components of dipole sources in the incoherent and coherent manners and the super resolution images can be reconstructed in the output plane. By tunning the parameters of the metallic nanoshell particle, the plasmon resonance band of the isolate nanoshell particle red-shifts to the near-infrared region. The near-infrared super resolution images are obtained subsequently. We calculate the field intensity distribution at the different planes of imaging process using the finite element method and find that the array has super resolution imaging capability at near-infrared wavelengths. We also show that the image formation highly depends on the coherence of the dipole sources and the image-array distance.

  3. [Latex allergy--Part I].

    Science.gov (United States)

    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.

  4. Identification and characterization of Euphorbia nivulia latex proteins.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 §...

  6. Universal shape characteristics for the mesoscopic polymer chain via dissipative particle dynamics

    Science.gov (United States)

    Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu; von Ferber, C.

    2016-12-01

    In this paper we study the shape characteristics of a polymer chain in a good solvent using a mesoscopic level of modelling. The dissipative particle dynamics simulations are performed in 3D space at a range of chain lengths N. The scaling laws for the end-to-end distance and gyration radius are examined first and found to hold for N≥slant 10 yielding a reasonably accurate value for the Flory exponent ν. Within the same interval of chain lengths, the asphericity, prolateness and some other shape characteristics of the chain are found to become independent of N. Their mean values are found to agree reasonably well with the respective theoretical results and lattice Monte Carlo (MC) simulations. We found the probability distribution for a wide range of shape characteristics. For the asphericity and prolateness they are quite broad, resembling in form the results of lattice MC simulations. By means of the analytic fitting of these distributions, the most probable values for the shape characteristics are found to supplement their mean values.

  7. String hypothesis for gl(n|m) spin chains: a particle/hole democracy

    CERN Document Server

    Volin, Dmytro

    2010-01-01

    This paper is devoted to integrable gl(n|m) spin chains which allow for formulation of the string hypothesis. Considering the thermodynamic limit of such spin chains, we derive linear functional equations that symmetricaly treat holes and particles. The functional equations naturally organize different types of excitations into a pattern equivalent to the one of Y-system, and, not surprisingly, the Y-system can be easily derived from the functional equations. The Y-system is known to contain most of the information about the symmetry of the model, therefore we map the symmetry knowledge directly to the description of string excitations. Our analysis is applicable for highest weight representations which for some choice of the Kac-Dynkin diagram have only one nonzero Dynkin label. This generalizes known results for the AdS/CFT spectral problem and for the Hubbard model.

  8. Predicting transient particle transport in enclosed environments with the combined computational fluid dynamics and Markov chain method.

    Science.gov (United States)

    Chen, C; Lin, C-H; Long, Z; Chen, Q

    2014-02-01

    To quickly obtain information about airborne infectious disease transmission in enclosed environments is critical in reducing the infection risk to the occupants. This study developed a combined computational fluid dynamics (CFD) and Markov chain method for quickly predicting transient particle transport in enclosed environments. The method first calculated a transition probability matrix using CFD simulations. Next, the Markov chain technique was applied to calculate the transient particle concentration distributions. This investigation used three cases, particle transport in an isothermal clean room, an office with an underfloor air distribution system, and the first-class cabin of an MD-82 airliner, to validate the combined CFD and Markov chain method. The general trends of the particle concentrations vs. time predicted by the Markov chain method agreed with the CFD simulations for these cases. The proposed Markov chain method can provide faster-than-real-time information about particle transport in enclosed environments. Furthermore, for a fixed airflow field, when the source location is changed, the Markov chain method can be used to avoid recalculation of the particle transport equation and thus reduce computing costs.

  9. Restrictions in Model Reduction for Polymer Chain Models in Dissipative Particle Dynamics

    KAUST Repository

    Moreno Chaparro, Nicolas

    2014-06-06

    We model high molecular weight homopolymers in semidilute concentration via Dissipative Particle Dynamics (DPD). We show that in model reduction methodologies for polymers it is not enough to preserve system properties (i.e., density ρ, pressure p, temperature T, radial distribution function g(r)) but preserving also the characteristic shape and length scale of the polymer chain model is necessary. In this work we apply a DPD-model-reduction methodology for linear polymers recently proposed; and demonstrate why the applicability of this methodology is limited upto certain maximum polymer length, and not suitable for solvent coarse graining.

  10. Latex allergy and filaggrin null mutations

    DEFF Research Database (Denmark)

    Carlsen, Berit C; Meldgaard, Michael; Hamann, Dathan

    2011-01-01

    Objectives Natural rubber latex (NRL) contains over 200 proteins of which 13 have been identified as allergens and the cause of type I latex allergy. Health care workers share a high occupational risk for developing latex allergy. Filaggrin null mutations increase the risk of type I sensitizations...... to aeroallergens and it is possible that filaggrin null mutations also increase the risk of latex allergy. The aim of this paper was to examine the association between filaggrin null mutations and type I latex allergy. Methods Twenty latex allergic and 24 non-latex allergic dentists and dental assistants......, occupationally exposed to latex, were genotyped for filaggrin null mutations R501X and 2282del4. Latex allergy was determined by a positive reaction or a historical positive reaction to a skin prick test with NRL. Results 41 individuals were successfully genotyped. Three individuals were filaggrin mutation...

  11. Anomalous dynamical scaling in anharmonic chains and plasma models with multi-particle collisions

    CERN Document Server

    Di Cintio, Pierfrancesco; Bufferand, Hugo; Ciraolo, Guido; Lepri, Stefano; Straka, Mika J

    2015-01-01

    We study the anomalous dynamical scaling of equilibrium correlations in one dimensional systems. Two different models are compared: the Fermi-Pasta-Ulam chain with cubic and quartic nonlinearity and a gas of point particles interacting stochastically through the Multi-Particle Collision dynamics. For both models -that admit three conservation laws- by means of detailed numerical simulations we verify the predictions of Nonlinear Fluctuating Hydrodynamics for the structure factors of density and energy fluctuations at equilibrium. Despite of this, violations of the expected scaling in the currents correlation are found in some regimes, hindering the observation of the asymptotic scaling predicted by the theory. In the case of the gas model this crossover is clearly demonstrated upon changing the coupling constant.

  12. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    Science.gov (United States)

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  13. Scattering of a particle with spin by atomic chain as null test of T-violating P-even magnetism

    CERN Document Server

    Cherkas, S L

    2000-01-01

    T-odd P-even long-range electromagnetic interaction of a particle of spin 1/2 with the nucleus is considered. Though matrix element of the interaction is zero for the particles on mass shell, nevertheless, null test exists for the interaction. The test consists in measuring of the spin-dependent T-odd P-even forward elastic scattering amplitude of a particle of spin 1/2 by atomic chain (axis) in a crystall.

  14. The latex story.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2007-01-01

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

  16. EVALUATION OF LOW-VOC LATEX PAINTS

    Science.gov (United States)

    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. Effect of silica fume and SBR latex on the pasteaggregate interfacial transition zone

    Directory of Open Access Journals (Sweden)

    João Adriano Rossignolo

    2007-03-01

    Full Text Available This paper deals with the effect of silica fume and styrene-butadiene latex (SBR on the microstructure of the interfacial transition zone (ITZ between Portland cement paste and aggregates (basalt. Scanning Electron Microscope (SEM equipped with energy dispersive x ray analysis system (EDX was used to determine the ITZ thickness. In the plain concrete a marked ITZ around the aggregate particles (55 µm was observed, while in concretes with silica fume or latex SBR the ITZ was less pronounced (35-40 µm. However, better results were observed in concretes with silica fume and latex SBR (20-25 µm.

  18. Optimization of Setup Frequency for TOC Supply Chain Replenishment Systems Based on Pareto Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Xiao-Yun Jiang

    2013-12-01

    Full Text Available The theory of constraints (TOC supply chain replenishment system (TOC-SCRS is an effective solution for coping with conflicts during the management of supply chain inventories. When it is deployed in a plant or a central warehouse with capacity constraints, TOC-SCRS encounters a problem comprised of 2 parts: first, how to establish a sound setup frequency (SF that can meet production needs and prevent losses from stock-outs, meaning a SF that allows the plant to make full use of its existing capacity to achieve maximal effective output. Second, it must determine how to establish a sound SF that can help the plant minimize its inventory and cut costs to the greatest possible extent. To resolve the problem, a SF optimization model for TOC-SCRS with capacity constraints is constructed and is then used in combination with Pareto particle swarm optimization (PSO to obtain SF optimization schemes in this paper. An illustrative example is conducted to verify the feasibility and effectiveness of the proposed approach.

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

    Science.gov (United States)

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

    2012-08-01

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

  20. 橡胶树胶乳橡胶粒子死皮相关蛋白的鉴定及分析%Identification and analysis of latex rubber particle proteins related with tapping panel dryness in Hevea brasiliensis

    Institute of Scientific and Technical Information of China (English)

    袁坤; 周雪梅; 王真辉; 杨礼富

    2014-01-01

    The tapping panel dryness ( TPD) in Hevea brasiliensis is one of the important factors influencing natural rub-ber production. In order to distinguish and identify the differentially expressed proteins of latex rubber particles in healthy and TPD trees, the two-dimensional electrophoresis (2-DE) was used. 35 differentially expressed protein spots were ob-tained by software analysis. Subjecting to MALDI-TOF MS following by searching for Uniprot rubber database, 13 protein spots were successfully identified, Of them, REF, FPS, GPX, GR, TCTP and HSP were mainly involed in the rubber biosynthesis, reactive oxygen metabolism and cell apoptosis processes. This study further showed that the pathways of the rubber biosynthesis, reactive oxygen metabolism and cell apoptosis were possibly the key regulated ones of TPD and which would provide a theoretical basis for elucidating the TPD mechanism in Hevea brasiliensis.%橡胶树死皮是影响天然橡胶产量的重要因子之一。采用双向凝胶电泳对健康树和死皮树橡胶粒子中差异表达的蛋白进行分离,分析获得35个差异表达的蛋白点,通过基质辅助激光解析电离飞行时间质谱( MALDI-TOF MS)分析及搜索Uniprot rubber数据库后,有13个蛋白点被成功鉴定,其中橡胶延长因子( rubber elongation factor,REF )、法尼基焦磷酸合成酶( Ffarnesyl-diphosphate synthase, FPS )、谷胱甘肽过氧化酶( glutathione peroxidase,GPX)、谷胱甘肽还原酶(glutathione reductase,GR)、翻译控制肿瘤蛋白(translationally controlled tumor protein,TCTP)、热激蛋白(heat shock protein, HSP)等主要蛋白参与了橡胶的生物合成、活性氧代谢及细胞凋亡过程。说明橡胶的生物合成、活性氧代谢及细胞凋亡途径可能是橡胶树死皮发生的关键调控途径。

  1. Cerium Biomagnification in a Terrestrial Food Chain: Influence of Particle Size and Growth Stage.

    Science.gov (United States)

    Majumdar, Sanghamitra; Trujillo-Reyes, Jesica; Hernandez-Viezcas, Jose A; White, Jason C; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2016-07-01

    Mass-flow modeling of engineered nanomaterials (ENMs) indicates that a major fraction of released particles partition into soils and sediments. This has aggravated the risk of contaminating agricultural fields, potentially threatening associated food webs. To assess possible ENM trophic transfer, cerium accumulation from cerium oxide nanoparticles (nano-CeO2) and their bulk equivalent (bulk-CeO2) was investigated in producers and consumers from a terrestrial food chain. Kidney bean plants (Phaseolus vulgaris var. red hawk) grown in soil contaminated with 1000-2000 mg/kg nano-CeO2 or 1000 mg/kg bulk-CeO2 were presented to Mexican bean beetles (Epilachna varivestis), which were then consumed by spined soldier bugs (Podisus maculiventris). Cerium accumulation in plant and insects was independent of particle size. After 36 days of exposure to 1000 mg/kg nano- and bulk-CeO2, roots accumulated 26 and 19 μg/g Ce, respectively, and translocated 1.02 and 1.3 μg/g Ce, respectively, to shoots. The beetle larvae feeding on nano-CeO2 exposed leaves accumulated low levels of Ce since ∼98% of Ce was excreted in contrast to bulk-CeO2. However, in nano-CeO2 exposed adults, Ce in tissues was higher than Ce excreted. Additionally, Ce content in tissues was biomagnified by a factor of 5.3 from the plants to adult beetles and further to bugs.

  2. Thermodynamic limit of particle-hole form factors in the massless XXZ Heisenberg chain

    Energy Technology Data Exchange (ETDEWEB)

    Kitanine, N. [Univ. de Bourgogne (France). IMB, UMR 5584 du CNRS; Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M.; Terras, V. [ENS Lyon (France). UMR 5672 du CNRS, Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Inst., Moscow (Russian Federation)

    2011-03-15

    We study the thermodynamic limit of the particle-hole form factors of the XXZ Heisenberg chain in the massless regime. We show that, in this limit, such form factors decrease as an explicitly computed power-law in the system size. Moreover, the corresponding amplitudes can be obtained as a product of a ''smooth'' and a ''discrete'' part: the former depends continuously on the rapidities of the particles and holes, whereas the latter has an additional explicit dependence on the set of integer numbers that label each excited state in the associated logarithmic Bethe equations. We also show that special form factors corresponding to zero-energy excitations lying on the Fermi surface decrease as a power-law in the system size with the same critical exponents as in the longdistance asymptotic behavior of the related two-point correlation functions. The methods we develop in this article are rather general and can be applied to other massless integrable models associated to the six-vertex R-matrix and having determinant representations for their form factors. (orig.)

  3. Thermodynamic limit of particle-hole form factors in the massless XXZ Heisenberg chain

    CERN Document Server

    Kitanine, N; Maillet, J M; Slavnov, N A; Terras, V

    2010-01-01

    We study the thermodynamic limit of the particle-hole form factors of the XXZ Heisenberg chain in the massless regime. We show that, in this limit, such form factors decrease as an explicitly computed power-law in the system-size. Moreover, the corresponding amplitudes can be obtained as a product of a "smooth" and a "discrete" part: the former depends continuously on the rapidities of the particles and holes, whereas the latter has an additional explicit dependence on the set of integer numbers that label each excited state in the associated logarithmic Bethe equations. We also show that special form factors corresponding to zero-energy excitations lying on the Fermi surface decrease as a power-law in the system size with the same critical exponents as in the long-distance asymptotic behavior of the related two-point correlation functions. The methods we develop in this article are rather general and can be applied to other massless integrable models associated to the six-vertex R-matrix and having determina...

  4. Improving Hydrologic Data Assimilation by a Multivariate Particle Filter-Markov Chain Monte Carlo

    Science.gov (United States)

    Yan, H.; DeChant, C. M.; Moradkhani, H.

    2014-12-01

    Data assimilation (DA) is a popular method for merging information from multiple sources (i.e. models and remotely sensing), leading to improved hydrologic prediction. With the increasing availability of satellite observations (such as soil moisture) in recent years, DA is emerging in operational forecast systems. Although these techniques have seen widespread application, developmental research has continued to further refine their effectiveness. This presentation will examine potential improvements to the Particle Filter (PF) through the inclusion of multivariate correlation structures. Applications of the PF typically rely on univariate DA schemes (such as assimilating the outlet observed discharge), and multivariate schemes generally ignore the spatial correlation of the observations. In this study, a multivariate DA scheme is proposed by introducing geostatistics into the newly developed particle filter with Markov chain Monte Carlo (PF-MCMC) method. This new method is assessed by a case study over one of the basin with natural hydrologic process in Model Parameter Estimation Experiment (MOPEX), located in Arizona. The multivariate PF-MCMC method is used to assimilate the Advanced Scatterometer (ASCAT) grid (12.5 km) soil moisture retrievals and the observed streamflow in five gages (four inlet and one outlet gages) into the Sacramento Soil Moisture Accounting (SAC-SMA) model for the same scale (12.5 km), leading to greater skill in hydrologic predictions.

  5. HIGH SOLIDS-CONTENT NANOSIZE POLYMER LATEXES MADE BY A MODIFIED EMULSION COPOLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuying; GUO Tianying; HAO Guangjie; SONG Maodao; Zhang Banghua

    2003-01-01

    Polymer nanoparticles were prepared in the methyl methacrylate (MMA)/buty lmethacrylate (BA) emulsion copolymerization process by a modified microemulsion copolymerization method. 2-Hydroxyethyl methacrylate(HEMA), acrylate (AA) and methyl acrylate (MAA) were used as reactive cosurfactants. With this process high polymer: surfactant weight ratios (40:1 or greater),relatively concentrated (~30wt. %) latexes and small (~60nm) particle diameters were obtained.Properties of the latexes were characterized by TEM, DSC, dynamic light scattering, and IR spectroscopy.

  6. Coadsorption of IgG and BSA onto sulfonated polystyrene latex: II. Colloidal stability and immunoreactivity.

    Science.gov (United States)

    Peula, J M; Hidalgo-Alvarez, R; de las Nieves, F J

    1995-01-01

    The present work deals with the study of the colloidal stability and immunoreactivity of sulfonated polystyrene latex particles covered by different amounts of m-BSA and IgG/a-CRP. These proteins have been previously adsorbed onto a sulfonated latex by sequential and competitive coadsorption experiments and it was possible to obtain latex-protein particles with different degrees of coverage by each protein. The latex particles, fully or partially covered by each protein (termed latex-protein complexes), were resuspended under several conditions (different pH and ionic strength values) and their colloidal stability, vs the addition of the electrolyte was studied using turbidity measurements. This stability appeared at a high degree of coverage by BSA and at a pH in which the BSA was negatively charged. At a high degree of coverage by IgG, the latex particles were unstable at all pHs. As a final part of this work, the immunoreactivity of several complexes was studied following the changes in the turbidity after the addition of CRP antigen. Only the complexes which were colloidally stable gave detectable reactivity. However, the complexes with a relatively low degree of coverage by IgG/a-CRP gave good immunoreactivity. Therefore, the latex-protein complex properties depended on the percentage of BSA or IgG adsorbed and on the electric state of the proteins at the redispersion pH. Under specific incubation conditions, sulfonated latex covered by significant IgG/BSA percentages was obtained, which showed a high colloidal stability and good immunoreactivity.

  7. Dissipative particle dynamics study of translational diffusion of rigid-chain rodlike polymer in nematic phase

    Science.gov (United States)

    Zhao, Tongyang; Wang, Xiaogong

    2013-09-01

    In this study, dissipative particle dynamics (DPD) method was employed to investigate the translational diffusion of rodlike polymer in its nematic phase. The polymer chain was modeled by a rigid rod composed of consecutive DPD particles and solvent was represented by independent DPD particles. To fully understand the translational motion of the rods in the anisotropic phase, four diffusion coefficients, D_{||}u, D_ bot u, D_{||}n, D_ bot n were obtained from the DPD simulation. By definition, D_{||}n and D_ bot n denote the diffusion coefficients parallel and perpendicular to the nematic director, while D_{||}u and D_ bot u denote the diffusion coefficients parallel and perpendicular to the long axis of a rigid rod u. In the simulation, the velocity auto-correlation functions were used to calculate the corresponding diffusion coefficients from the simulated velocity of the rods. Simulation results show that the variation of orientational order caused by concentration and temperature changes has substantial influences on D_{||}u and D_ bot u. In the nematic phase, the changes of concentration and temperature will result in a change of local environment of rods, which directly influence D_{||}u and D_ bot u. Both D_{||}n and D_ bot n can be represented as averages of D_{||}u and D_ bot u, and the weighted factors are functions of the orientational order parameter S2. The effect of concentration and temperature on D_{||}n and D_ bot n demonstrated by the DPD simulation can be rationally interpreted by considering their influences on D_{||}u, D_ bot u and the order parameter S2.

  8. Latex Allergy - A Case Report

    Directory of Open Access Journals (Sweden)

    Dr. Athma Prasanna

    2005-10-01

    Full Text Available The usage of rubber and its products are not uncommon in various walks of life. A continuous exposure or contact may sensitize the human body, causing reactions from mild to fatal. Despite the availability of the literature, medical personnel are still unaware of the implications of the use of latex materials.

  9. Parametric characterizations in superparamagnetic latex

    Indian Academy of Sciences (India)

    Seda Beyaz; Hakan Kockar; Taner Tanrisever

    2014-05-01

    The effect of synthesis parameters on the production of superparamagnetic latex, which are magnetite nanoparticles covered with a poly(methyl methacrylate) layer, were studied. The synthesis method was based on the developed route of emulsifier-free emulsion polymerization. Under this study, effects of the monomer and initiator concentrations, the amount of magnetic sol, the stirring rate and the adding rate of the magnetic sol on the properties of synthesized latexes were investigated. The characterizations were performed by a high resolution transmission electron microscopy, a dynamic light scattering, a vibrating sample magnetometer and a gel permeation chromatography. The results showed that the monomer concentration was found to be the most effective parameter on latex stability. As the initiator amount and the stirring rate increased, saturation magnetization and average molecular weight decreased due to the reactions occurring between surfaces of magnetite nanoparticles and initiator fragments. On increasing amount of magnetic sol, the saturation magnetization and polymer molecular weight increased but the size of nanospheres was unchanged because of the ions in magnetic sol. It was seen that the desired size and magnetic properties of the latex could be obtained since the parameters were found to have substantial impact on their properties.

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

    Science.gov (United States)

    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.

  11. Latex agglutination test for field diagnosis of haemorrhagic septicaemia

    Directory of Open Access Journals (Sweden)

    Lily Natalia

    2002-10-01

    Full Text Available Pasteurella multocida is bacterial pathogens that cause haemorrhagic septicaemia (HS in cattle and buffaloes. Various tests have been used to differentiate types of P. multocida, as well as to diagnose this specific disease. A latex agglutination test has been developed for the detection of P. multocida B:2 which is the causal agent of HS. This test is a rapid and simple test suitable for local laboratorium to diagnose HS cases in the field. A heat stable antigen consisting of mainly lipopolysaccharide (LPS extract of formalin killed P. multocida 0019 was used to produce specific antibody against P. multocida B:2. The antiboy was then used to sensitise latex particles. Latex agglutination test have been used to screen some P. multocida field isolates and this test have been proven to be specific, simple and easy to be used in detecting P. multocida B:2. The specificity is due to antibodies recognising LPS or LPS protein complexes. Sensitised latex was stable at 4° C for at least12 months. This test should be used as an aid to diagnosis and employed principally to confirm and support clinical and post mortem findings of HS.

  12. Design of colored multilayered electrophoretic particles for electronic inks.

    Science.gov (United States)

    Badila, M; Hébraud, A; Brochon, C; Hadziioannou, G

    2011-09-01

    The preparation of multilayered latex particles with surface functional groups suitable for use as electrophoretic particles in electronic inks has been studied. The particles are formed by dispersion polymerization and have a polystyrene core, slightly cross-linked with divinylbenzene (DVB), and a poly(methyl methacrylate) (PMMA) or a poly(acrylic acid) (PAA) shell. After grafting alkyl chains on their surface, the particles are negatively or positively charged and sterically stabilized against aggregation in nonpolar solvent. The particles were dyed by incorporation of Nigrosin during polymerization or by swelling in supercritical CO(2) in the presence of a dye. Particle size, morphology, incorporated dye content and zeta potential were determined. A dual-particle electronic ink based on a mixture of the colored multilayered particles and white hybrid TiO(2)-polymer particles was prepared and electro-optically tested.

  13. Thermal conductivity and dynamics of a chain of free and bound particles

    Science.gov (United States)

    Mimnagh, Dominic James Redmond

    The proportionality of heat current, J, to temperature gradient, nabla T, is an accepted tenet of thermal physics, Fourier's law, and can be written as J = {-}kappanabla T, where kappa represents the thermal conductivity. This behaviour has been shown empirically, but is difficult to derive from first principles. In the past, the thermal conductivity has been calculated for many different dynamical models to help shed light on the foundations of Fourier's law. Systems that have a finite kappa that is also an intensive property of the lattice are considered to have normal thermal conductivity. Surprisingly, this property has been demonstrated for only two dynamical systems. One is the well known Toda model (a lattice of exponentially bound particles) the other is the ding-a-ling model (a lattice of alternately free and harmonically bound particles) (G. Casati, J. Ford, F. Vivaldi, and W. M. Visscher, Physical Review Letters 52, 1861 (1984)). The initial aim of the research was to measure dynamic quantities of the ding-a-ling model and to look for correlations with a possible transition to normal thermal conductivity. This work was delayed initially when we were unable to confirm Casati, Ford, Vivaldi, and Visscher's (CFVV) assertion that the thermal conductivity of the ding-a-ling model was independent of chain length. We have shown that what CFVV quote as an asymptotic value of kappa is only a transitory plateau, and kappa actually increases for longer chains. Ultimately, however, a saturation value can be established and CFVV's conclusion that the ding-a-ling model displays normal thermal conductivity is correct. In fact, the model appears to possess normal thermal conductivity for all parameter values explored, though it does demonstrate a transition in the length of chain needed to observe this Fourier law behaviour. We were able to demonstrate that this transition in scale coincides with transitions in a number of dynamical measures of the system, such as, the

  14. Synthesis of P(St-BA-MAA-SPAA) nano-latex and its application in high anti-corrisive coating

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-feng; SHENG Ming-shuang; PAN Zhao-ji; QIU Da-jian; GUO Zhi-hua; GAN Fu-xing

    2008-01-01

    A novel zinc-rich pigment based on P(St-BA-MAA-SPAA) nano-latex was obtained, which is suitable for the use in hot alkali liquid medium. The nano-latex was synthesized by active emulsifier latex polymerization method with monomers of styrene(St), butylaerylate (BA), methylacrylic acid(MAA) in the presence of active emulsifier 3-sulfopropylaerylate(SPAA). The synthesis condition and properties of the latex were investigated. And the anti-corrosive property of the resultant zinc-rich coating was studied. The results show that the nano-latex is self-stabilized and has a narrow particle diameter distribution, the average diameter of the latex particles is 71 nm. Zinc powders can be evenly dispersed in the nano-latex, which indicates that the P(St-BA-MAA-SPAA)nano latex can be used as the binder of zinc-rich coating. The resultant zinc-rich coating is able to resist the invasion of hot alkali solution(the temperature is 95 ℃ and the pH value is 14) for 480 h and the exposure time in salt spray is 1 200 h. Moreover, the coating shows good thermal conductivity and static electricity properties, its thermal conductivity and electric resistivity are 21-37 W/(m·K) and 6.7×105-3.5×106 Ω.cm, respectively

  15. Relevance of latex aeroallergen for healthcare workers

    Directory of Open Access Journals (Sweden)

    X. Baur

    1996-01-01

    Full Text Available The dispersion of latex allergen bound on glove powder has been shown to be of clinical importance to latex-sensitized medical staff and patients. To investigate whether latex aeroallergen is associated with the development of latex allergic reactions in health care workers, air samples were collected in 33 hospital rooms and two physicians' offices. Concentrations of latex allergens in the samples were determined by a competitive inhibition immunoassay and related to reported hypersensitivity reactions and to specific IgE results of 111 staff members engaged in these rooms. Latex aeroallergen (up to 205 ng/m3 could be detected in all rooms where powdered latex gloves were used and ventilation systems were not installed. Conjunctivitis (n=10, rhinitis (n=12 and dyspnea (n=4 were reported exclusively by employees working in such contaminated rooms. Also workers with latex-specific IgE antibodies (n=l 7 were found only in these rooms. Urticaria in personnel (n=26 was reported in rooms with and without detectable allergen load. All symptoms were significantly associated with latex-specific IgE antibodies. Our results demonstrate that immediate-type sensitization and allergic symptoms are associated with detectable latex aeroallergen.

  16. The structure and properties of Fe3O4/P (NaUA-St-BA) magnetic composite nano particles

    Institute of Scientific and Technical Information of China (English)

    周春华; 张书香; 刘威; 王英姿; 杨鸿昌

    2004-01-01

    Fe3O4/P (NaUA-St-BA) core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3 O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties.Finally, the prepared magnetic composite particles latex is stable for several months.

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

    Science.gov (United States)

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

    2010-01-01

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

  18. Latex-protein complexes from an acute phase recombinant antigen of Toxoplasma gondii for the diagnosis of recently acquired toxoplasmosis.

    Science.gov (United States)

    Peretti, Leandro E; Gonzalez, Verónica D G; Marcipar, Iván S; Gugliotta, Luis M

    2014-08-01

    The synthesis and characterization of latex-protein complexes (LPC), from the acute phase recombinant antigen P35 (P35Ag) of Toxoplasma gondii and "core-shell" carboxylated or polystyrene (PS) latexes (of different sizes and charge densities) are considered, with the aim of producing immunoagglutination reagents able to detect recently acquired toxoplasmosis. Physical adsorption (PA) and chemical coupling (CC) of P35Ag onto latex particles at different pH were investigated. Greater amounts of adsorbed protein were obtained on PS latexes than on carboxylated latexes, indicating that hydrophobic forces govern the interactions between the protein and the particle surface. In the CC experiments, the highest amount of bound protein was obtained at pH 6, near the isoelectric point of the protein (IP=6.27). At this pH, it decreased both the repulsion between particle surface and protein, and the repulsion between neighboring molecules. The LPC were characterized and the antigenicity of the P35Ag protein coupled on the particles surface was evaluated by Enzyme-Linked ImmunoSorbent Assay (ELISA). Results from ELISA showed that the P35Ag coupled to the latex particles surface was not affected during the particles sensitization by PA and CC and the produced LPC were able to recognize specific anti-P35Ag antibodies present in the acute phase of the disease.

  19. 乳胶粒化学改性酚醛树脂合成闸片的制动性能研究%Braking Performance of Hybrid Fibers Reinforced Brake Pad with Latex Particle Modified Phenolic Resin Binder

    Institute of Scientific and Technical Information of China (English)

    王海庆; 吴行阳; 周广荣; 丛培红

    2011-01-01

    A latex particle modified phenolic resin was designed and developed to manufacture organic brake pad for electric power locomotive brake. The braking performance was evaluated on a full - scale test bench at Vehicle Inspection Station of Product Quality Monitoring Center of Railway Ministry, People's Republic of China, according to the Europe standard UIC 541 - 3: 2006 and Standard of China Railway Ministry TB/T 3118 - 2005 ( the central line speed at brake pad was 41.8 m/s at the highest speed of 200 km/h ). The test results indicated that the average dry friction coefficient of the brake pad under different braking speeds ranged from 0.29 to 0.57, the average static friction coefficient was 0.47, and the wear rate of the pad was O. 2 cm3/MJ after 36 times of braking tests. All the above results satisfied the required values of UIC 541 -3: 2006. No bulges, loss of rubbing material, cracks and metal - embedded deposits were observed on the brake pad after the whole tests. FTIR analysis results indicated that chemical structure of the pad was similar to the polymer matrix, and no obvious tribochemical reactions were confirmed. All the results suggest that the new type organic brake pad may realize application for the brake of “Hexie” electric power locomotive.%采用自制的环保型乳胶粒化学改性酚醛树脂为粘结剂制备了和谐号电力机车用轮装式有机合成闸片,参照欧洲标准UIC 541-3:2006和我国铁道部标准TB/T 3118-2005规定的试验程序,在铁道部产品质量监督检验中心机车车辆检验站进行了闸片的制动性能试验(最高速度200 km/h时制动闸片中心线速度为41.8 m/s).试验结果表明该闸片在不同初始速度干燥条件下的平均摩擦系数在0.29~0.57,静摩擦系数平均值为0.47,36闸后的磨损率约为0.2 cm3/MJ,满足UIC 541-3:2006中规定的指标.表面形貌观察发现制动试验后闸片无开裂、掉渣、塌边和皴裂等现象,红外分析发现闸片摩擦

  20. Preparation of CO₂/N₂-triggered reversibly coagulatable and redispersible polyacrylate latexes by emulsion polymerization using a polymeric surfactant.

    Science.gov (United States)

    Zhang, Qi; Yu, Guoqiang; Wang, Wen-Jun; Li, Bo-Geng; Zhu, Shiping

    2012-05-29

    We report here a novel approach for making reversibly coagulatable and redispersible polyacrylate latexes by emulsion (co)polymerization of methyl methacrylate (MMA) using a polymeric surfactant, poly(2-(dimethylamino)ethyl methacrylate)(10) -block-poly(methyl methacrylate)(14) . The surfactant was protonated with HCl prior to use. The resulted PMMA latexes were readily coagulated with trace amount of caustic soda. The coagulated latex particles, after washing with deionized water, could be redispersed into fresh water to form stable latexes again by CO(2) bubbling with ultrasonication. The recovered latexes could then be coagulated by N(2) bubbling with gentle heating. These coagulation and redispersion processes were repeatable by the CO(2) /N(2) bubbling.

  1. Particle bridging in dispersions by small charged molecules: chain length and rigidity, architecture and functional groups spatial position.

    Science.gov (United States)

    Leong, Yee-Kwong

    2007-11-07

    The particle bridging behaviour of dicarboxylic acid bolaform compounds such as fumaric, oxalic,trans-beta-hydromuconic, trans,trans- and cis,cis-muconic acids were evaluated in terms of their effects on the yield stress of alpha-Al(2)O(3) dispersions. The adsorption behaviour of these additives and their effects on the particle zeta potential were also determined. This study aims to understand and identify molecular factors essential for particle bridging. Very rigid compounds like trans,trans- and cis,cis-muconic and fumaric acids were identified as excellent bridging compounds from the large increase in the maximum gel strength. This strength enhancement increases with chain length and is due to more bridging molecules located in the larger spherical cap bridging area and participating in bridging. Cis,cis-muconic acid with the same chain length as fumaric acid displayed a greater bridging capability as its bolaform carboxylate groups possessed a greater lateral reach. Trans-beta-hydromuconic acid with a more flexible backbone displayed a much diminished particle bridging capability. This study has revealed a number of new molecular structural factors essential for particle bridging attribute. These are (a) the degree of backbone rigidity, (b) chain length, (c) spatial position and (d) lateral displacement of the bolaform charged group. For fumaric, trans,trans- and cis,cis-muconic acids, the maximum gel strength was not located at the pH of zero zeta potential. A particle bridging model taking into account of electrostatic repulsive interactions between the interacting particles was proposed to explain the maximum gel strength enhancement by the bolaform compounds.

  2. Soliton-Like Pulses in Vertical Granular Chain Under Gravity: Particle-Like or Wave-Like?

    Institute of Scientific and Technical Information of China (English)

    XU Ai-Guo; HONG Jongbae

    2001-01-01

    We numerically study the propagation, reflection and collision of soliton-like pulses in the vertical granular chain under gravity. For the pure granular chain system, during the propagation and reflection processes at the fixed end, it behaves like a particle. When it is reflected at the free end, it behaves as neither particle-like nor wave-like.When the strengths of the two colliding soliton-like pulses are close, they collide just like particles. When their strengths are greatly different, they collide just like waves. For the soliton behavior in the collision process, from particle-like to wave-like, there is a critical value θC for the ratio θ of the strengths of the two initial pulses. For the two-layer granular chain, if the mass of the grains in the second layeris less than that in the first layer, the soliton-like pulse in the first layer usually excites about [1/m] soliton-like pulses in the second layer.``

  3. Nitrile versus Latex for Glove Juice Sampling.

    Science.gov (United States)

    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 (platex in glove juice sampling methods, since nitrile avoids the risk of latex exposure.

  4. Latex Allergy with Discus Form of Inhalation Drug of Asthma

    Directory of Open Access Journals (Sweden)

    Ogun Sezer

    2009-10-01

    Full Text Available The prevalence of latex allergy in healthcare workers and which was taken chronic medical therapy has significantly increased during the last 15 years. Latex allergy generally refers to a type 1 reaction to natural rubber latex (NRL proteins with clinical manifestations ranging from contact urticaria to asthma and anaphylaxis. In this report, we discuss latex allergy with discus form of inhalation drug of asthma after contact of discus form to lips. Still, latex allergy is an important problem in patients with latex allergy. We must inform all patients about latex allergy and all latex containing devices. [TAF Prev Med Bull 2009; 8(5.000: 451-452

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

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Pairu; Zin, Wan Manshol Wan [Malaysian Nuclear Agency, 43000 kajang, Selangor (Malaysia); Daik, Rusli [Faculty of Science and Technology, Universiti Kebangsaan Malaysia,43600 bangi, Selangor (Malaysia)

    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.

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

    Science.gov (United States)

    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.

  7. Latex Allergy In Health Care Workers

    Directory of Open Access Journals (Sweden)

    Hayriye Sarıcaoğlu

    2013-05-01

    Full Text Available Background and Design: We aimed to determine the frequency of latex allergy in our hospital and to to evaluate the clinical and demographical features of the cases.Materials and Methods: A detailed questionnaire was administered to healthcare workers by a physician. Skin prick test with latex and patch test with rubber chemicals and a piece of latex glove were performed for all healthcare workers. Latex-specific IgE was measured in serum.Results: The study sample consisted of 36 nurses, 14 doctors, and 50 healthcare workers. While 46 subjects had symptoms, 54 subjects had no symptoms. The relationship of clinical disease with working duration, exposure duration (hour/day, history of atopy, and drug/food allergies was statistically significant. Five nurses and 1 healthcare worker had positive skin prick test. Two of them had positive latex-specific IgE. Positive skin prick test statistically significantly correlated with occupation, working duration, exposure duration (hour/day and positive latex-specific IgE. Two nurses and 2 healthcare workers had positive latex-specific IgE. Two of them had positive skin prick test. Positive latexspecific IgE statistically significantly correlated with working duration, exposure duration, and positive skin prick test. Patch test with a piece of latex glove was negative in all subjects. Three healthcare workers had positive patch test with thiuram-mix, one of them had also positive patch test with mercaptobenzothiazole.Discussion: One of the risk factors for latex allergy is occupations involving frequent exposure to latex products. Latex allergy should be taken into consideration if type I hypersensitivity reactions occur in occupational groups at risk for anaphylactic reaction.

  8. Ficus carica latex-mediated synthesis of silver nanoparticles and its application as a chemophotoprotective agent.

    Science.gov (United States)

    Borase, Hemant P; Patil, Chandrashekhar D; Suryawanshi, Rahul K; Patil, Satish V

    2013-10-01

    The present work provides scientific support on the use of latex of Ficus carica to synthesize stable silver nanoparticles (AgNPs). AgNPs synthesized immediately after the addition of latex to silver nitrate solution at room temperature. Synthesized nanoparticles were of spherical shape with average size of 163.7 nm. Fourier transform infrared spectroscopy analysis revealed capping of proteins and phenolic compound on AgNPs, while X-ray diffraction analysis confirmed the fcc nature of AgNPs. Particles formed were stable for a long time (6 months). It was found that incorporation of AgNPs with 2 and 4% concentration exhibits synergistic increase in sun protection factor of commercial sunscreen and natural extracts ranging from 01 to 12,175% than control. Further characterization of latex and AgNPs revealed total phenolic content of 98.75 and 94.88 μg/ml. The ferric ion reduction potentials of latex and AgNPs were 79.69 and 18.79%. Reduction potential of ascorbic acid was synergistically increased after cumulative preparation of ascorbic acid with latex and AgNPs and found to be 106.76 and 101.50% for ascorbic acid + latex and ascorbic acid + AgNPs, respectively.

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

    Science.gov (United States)

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

    2014-06-01

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

  10. Jackfruit anaphylaxis in a latex allergic patient.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false User labeling for latex condoms. 801.435 Section... latex condoms. (a) This section applies to the subset of condoms as identified in § 884.5300 of this... products are formed from latex films. (b) Data show that the material integrity of latex condoms...

  12. EFFECT OF THE PHASE STRUCTURE EVOLUTION ON THE PROPERTIES OF FILMS FORMED FROM PBA/P(ST-CO-MMA)COMPOSITE LATEX

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A group of heterogeneous latexes poly(butyl acrylate)/poly(styrene-co-methyl methacrylate)(PBA/P(St-co-MMA))were prepared by a semi-continuous seeded emulsion polymerization process under monomer starved conditions.The glass transition temperature(Tg)and the mechanical properties of the film formed from the composite latex changed with the evolution of the particle morphology.A photon transmission method was used to monitor the phase structure evolution of films which were prepared from core-shell PBA/P(St-co-MMA)latex at room temperature and annealed at 383 K above Tg of the polymers.In addition,the changes of the surface of the film formed from the composite latex with time at 383 K were observed by AFM.The evidence illustrated that the film formed from the core-shell latex particles was metastable.The rearrangement of the phases could occur under proper conditions.

  13. Phase-coexistence simulations of fluid mixtures by the Markov Chain Monte Carlo method using single-particle models

    KAUST Repository

    Li, Jun

    2013-09-01

    We present a single-particle Lennard-Jones (L-J) model for CO2 and N2. Simplified L-J models for other small polyatomic molecules can be obtained following the methodology described herein. The phase-coexistence diagrams of single-component systems computed using the proposed single-particle models for CO2 and N2 agree well with experimental data over a wide range of temperatures. These diagrams are computed using the Markov Chain Monte Carlo method based on the Gibbs-NVT ensemble. This good agreement validates the proposed simplified models. That is, with properly selected parameters, the single-particle models have similar accuracy in predicting gas-phase properties as more complex, state-of-the-art molecular models. To further test these single-particle models, three binary mixtures of CH4, CO2 and N2 are studied using a Gibbs-NPT ensemble. These results are compared against experimental data over a wide range of pressures. The single-particle model has similar accuracy in the gas phase as traditional models although its deviation in the liquid phase is greater. Since the single-particle model reduces the particle number and avoids the time-consuming Ewald summation used to evaluate Coulomb interactions, the proposed model improves the computational efficiency significantly, particularly in the case of high liquid density where the acceptance rate of the particle-swap trial move increases. We compare, at constant temperature and pressure, the Gibbs-NPT and Gibbs-NVT ensembles to analyze their performance differences and results consistency. As theoretically predicted, the agreement between the simulations implies that Gibbs-NVT can be used to validate Gibbs-NPT predictions when experimental data is not available. © 2013 Elsevier Inc.

  14. Regenerated cellulose fibers spun-dyed with carbon black/latex composite dispersion.

    Science.gov (United States)

    Wang, Chunxia; Du, Changsen; Tian, Anli; Fu, Shaohai; Xu, Changhai

    2014-01-30

    A carbon black (CB)/latex composite was prepared by the method of miniemulsion polymerization for use as a colorant for spun dyeing of regenerated cellulose fibers. Analysis of experimental results revealed that the CB/latex composite had a small particle size and a narrow particle size distribution which were important to ensure a stable dispersion being later added to spinning solution. A good stability of the prepared CB/latex composite dispersion in the spinning solution indicated that it was highly possible to use the CB/latex composite as a colorant for spun dyeing of regenerated cellulose fibers. When a 3.5% mass ratio of CB/latex composite to cellulose was used for spun dyeing, the spun-dyed fibers had the highest tensile strength, breaking elongation and color strength. The rubbing and washing color fastnesses of spun-dyed regenerated cellulose fibers could satisfy requirements of most textiles. This study provided a new insight into producing spun-dyed regenerated cellulose with a novel colorant.

  15. String Hypothesis for [InlineMediaObject not available: see fulltext.] Spin Chains: A Particle/Hole Democracy

    Science.gov (United States)

    Volin, Dmytro

    2012-10-01

    This paper is devoted to integrable {{{g}{l} ({n} | {m})}} spin chains, which allow for formulation of the string hypothesis. Considering the thermodynamic limit of such spin chains, we derive linear functional equations that symmetrically treat holes and particles. The functional equations naturally organize different types of excitations into a pattern equivalent to the one of Y-system, and, not surprisingly, the Y-system can be easily derived from the functional equations. The Y-system is known to contain most of the information about the symmetry of the model, therefore we map the symmetry knowledge directly to the description of string excitations. Our analysis is applicable for highest weight representations which for some choice of the Kac-Dynkin diagram have only one nonzero Dynkin label. This generalizes known results for the AdS/CFT spectral problem and for the Hubbard model.

  16. A Particle Swarm Optimization Algorithm for Optimal Operating Parameters of VMI Systems in a Two-Echelon Supply Chain

    Science.gov (United States)

    Sue-Ann, Goh; Ponnambalam, S. G.

    This paper focuses on the operational issues of a Two-echelon Single-Vendor-Multiple-Buyers Supply chain (TSVMBSC) under vendor managed inventory (VMI) mode of operation. To determine the optimal sales quantity for each buyer in TSVMBC, a mathematical model is formulated. Based on the optimal sales quantity can be obtained and the optimal sales price that will determine the optimal channel profit and contract price between the vendor and buyer. All this parameters depends upon the understanding of the revenue sharing between the vendor and buyers. A Particle Swarm Optimization (PSO) is proposed for this problem. Solutions obtained from PSO is compared with the best known results reported in literature.

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

    Science.gov (United States)

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

    2008-01-29

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

  18. Synthesis, characterization and gold loading of polystyrene-poly(pyridyl methacrylate) core–shell latex systems

    NARCIS (Netherlands)

    Oláh, Attila; Hempenius, Mark A.; Vancso, G. Julius

    2004-01-01

    In this research, novel 3-(2-pyridyl)propyl methacrylate and 3-(3-pyridyloxy)propyl methacrylate monomers were synthesized and emulsion polymerized on colloidal polystyrene seeds, resulting in core–shell latex systems. The cores and the core–shell particles were characterized by static light scatter

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

    Science.gov (United States)

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

    2015-11-10

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

  20. In vitro cytotoxicity evaluation of natural rubber latex film surface coated with PMMA nanoparticles.

    Science.gov (United States)

    Anancharungsuk, Waranya; Polpanich, Duangporn; Jangpatarapongsa, Kulachart; Tangboriboonrat, Pramuan

    2010-07-01

    In order to increase surface roughness of the sulphur-prevulcanized natural rubber (SPNR) film and, hence, decrease the direct contact between the rubber and skin, the poly(methyl methacrylate) (PMMA) latex particles were deposited onto the SPNR film grafted with polyacrylamide (SPNR-g-PAAm). The surface coverage of PMMA particles on the SPNR-g-PAAm increased with increasing latex immersion time, particle size and concentration. Prior to the in vitro cytotoxicity evaluation on L-929 fibroblasts, the SPNR and SPNR-g-PAAm coated with PMMA particles were extracted by using the culture medium. Results showed that the cytotoxicity effect could be significantly reduced by coating PMMA particles onto the rubber film. At the extract concentrations of < or =12.5% for 24h at 37 degrees C, no toxicity potential was detected. The study will be helpful for development of gloves designed for the hypersensitive person.

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

    Science.gov (United States)

    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.

  2. Allergy to latex in health workers

    Directory of Open Access Journals (Sweden)

    Fajardo-Zapata, Álvaro L.

    2015-01-01

    Full Text Available Introduction: A common and growing problem in hospitals is hypersensitivity to rubber latex antigens, since many products, including gloves, are manufactured from this material, with the consequent possibility of producing allergy in persons who use them. Objective: To find out if health workers at a fourth level clinic in Bogotá, Colombia, are allergic to rubber latex, in relation to the use of gloves. Materials and methods: Descriptive, cross-sectional study of a non-probabilistic intentional-type sample in each one of four hospital units. A survey was applied to participants. Results: 16 of the 26 persons (61.5% with history of allergic processes manifested some kind of reaction when they had contact with latex gloves; the problem was more significant in the nursing personnel compared to physicians. Conclusions: The exposure to latex gloves may be generating the appearance of allergic occupational disease in health workers.

  3. Synthesis of 3-D ordered macroporous silicate using the template formed from monodispersed polystyrene latex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the template formed from monodispersed polystyrene (PS) latex, a modified fast sol-gel process was employed to synthesize a three-dimensional ( 3-D ) ordered macroporous silica material after removing the template by calcination at high temperature. It was indicated that there existed highly ordered packed pores within the whole silica material by SEM morphology observation. It was also found that the pores were interconnected. The pore size could be controlled mainly by varying the particle size of the latex ranging from 101 to 102 nm. The formation process of the ordered pores was also preliminarily discussed.

  4. IDENTIFICATION OF BACTERIA IN LATEX PAINTS

    Directory of Open Access Journals (Sweden)

    Rojas, J.

    2008-01-01

    Full Text Available The bacteria are prokaryote organisms with a high capacity to colonize many types of habits. This research was developed with the object to identify extremophiles bacteria presents in latex paint. The bacteria were cultivated in culture mediums TSA, Blood Agar, Mc Conkey and finally the biochemical proof API-NF® for bacteria's isolation and identification, respectively. Characterization showed bacterial profile of Pasteurella sp. Hypothesis that could be found extremophiles bacteria in latex paint were demonstrated.

  5. Spontaneous ordering of magnetic particles in liquid crystals: From chains to biaxial lamellae.

    Science.gov (United States)

    Peroukidis, Stavros D; Klapp, Sabine H L

    2015-07-01

    Using Monte Carlo computer simulations we explore the self-assembly and ordering behavior of a hybrid, soft magnetic system consisting of small magnetic nanospheres in a liquid-crystalline (LC) matrix. Inspired by recent experiments with colloidal rod matrices, we focus on conditions where the sphere and rod diameters are comparable. Already in the absence of a magnetic field, the nematic ordering of the LC can stabilize the formation of magnetic chains along the nematic or smectic director, yielding a state with local (yet no macroscopic) magnetic order. The chains, in turn, increase the overall nematic order, reflecting the complex interplay of the structure formation of the two components. When increasing the sphere diameter, the spontaneous uniaxial ordering is replaced by biaxial lamellar morphologies characterized by alternating layers of rods and magnetic chains oriented perpendicular to the rod's director. These ordering scenarios at zero field suggest a complex response of the resulting hybrid to external stimuli, such as magnetic fields and shear forces.

  6. Preparation and Structural Characterization of Hydroxylethyl Methacrylate Grafted Natural Rubber Latex

    Directory of Open Access Journals (Sweden)

    Feiyun Wei

    2014-06-01

    Full Text Available The graft copolymer with semi-interpenetrating polymer networks (semi-IPNs from 2-hydroxyethyl methacrylate (HEMA and natural rubber (NR latex was prepared using cumene hydroperoxide and tetraethylene pentamine redox initiator system. The changes of grafting ratios and grafting efficiency with the reaction time and temperature, the concentration of crosslinking agent, initiator and monomer were investigated. The appropriate amounts of crosslinking agent (0.1phr, initiator (0.2phr and monomer (20phr and the optimum reaction conditions of 16ºC×8h were determined. The swelling temperature and times of monomers against NR latex particles were found to be significant for the grafting copolymerization and the appropriate swelling conditions were 16ºC×20h. The water contact angle measurement and platelet adhesion evaluation indicated that the hydrophilicity and blood compatibility of NR latex could be improved by grafting copolymerization with HEMA.

  7. Interaction of a spirooxazine dye with latex and its photochromic efficiency on cellulosic paper.

    Science.gov (United States)

    Sun, Bo; He, Zhibin; Hou, Qingxi; Liu, Zehua; Cha, Ruitao; Ni, Yonghao

    2013-06-05

    Spirooxazine (SO) is a class of important photochromic dyes for many applications, such as anti-counterfeiting printing, reversible memory photo devices and optical switching elements in molecular electronics. Since these dyes are expensive, improving their coloration efficiency in response to photo stimuli is of practical importance. In this study, a spirooxazine dye, 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3'-[3H]naphtha[2,1-b][1,4]oxazine], was dispersed into the substrate of a polystyrene acrylic latex emulsion to obtain a stable photochromic dye loaded latex. The photochromic latex was then applied on cellulose paper, and its coloration efficiency was significantly higher than the control (without the latex). Transmission electron microscope (TEM) observation revealed that the spirooxazine dye was well dispersed into the matrix of the latex particles, which functioned as a carrier/dispersant for the photochromic dye. Other results, including color stability, and fatigue resistance, were also discussed.

  8. Synthesis and properties of acrylate latex modified by vinyl alkoxy siloxane

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emulsifiers at (78±2) ℃. The effects of different factors, such as the emulsifier, C-1706 monomer and its feeding manner on the properties of aciylate latex modified by C-1706 were investigated. The particle size distribution and the structure, the configuration, the weather durability and stain resistance of copolymer latex were characterized by particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM) and ultraviolet aging instrument respectively. The results show that SDS to OP-10 as multiple emulsifiers can lead to coordinated efficiency, the optimal emulsifier dosage is 2.4%-3.2%(mass fraction), and the mass ratio of SDS to OP-10 is 1:1- 1:2. The seeded emulsion polymerization can effectively introduce a organic-siloxane bonding in a macromolecule inter polymer, and the obtained acrylate latex modified by organic-siloxane possesses narrow distribution of particle size with mean diameter of 51.8-76.6 nm and has the excellent properties in weather durability and stain-resistance especially.

  9. Dynamics of a chain of magnetic particles connected with elastic linkers

    CERN Document Server

    Cebers, A

    2003-01-01

    The model of an elastic magnetic chain is considered. By numerical simulation of the dynamics of rod shapes acted on by magnetic and elastic forces in viscous fluid, it is shown that the characteristic 'U'-like metastable shapes (hairpins) can be formed. The characteristic 'S'-like long-living shapes are formed at intermediate stages, depending on the initial perturbation of the rod, and finally relax to the global energy minima corresponding to the straight rod. Further extensions of the model will include long-range magnetic interactions between distant parts of a rod.

  10. Asymptotic Bethe Ansatz on the GKP vacuum as a defect spin chain: scattering, particles and minimal area Wilson loops

    CERN Document Server

    Fioravanti, Davide; Rossi, Marco

    2015-01-01

    Moving from Beisert-Staudacher equations, the complete set of Asymptotic Bethe Ansatz equations and $S$-matrix for the excitations over the GKP vacuum is found. The resulting model on this new vacuum is an integrable spin chain of length $R=2\\ln s$ ($s=$ spin) with particle rapidities as inhomogeneities, two (purely transmitting) defects and $SU(4)$ (residual R-)symmetry. The non-trivial dynamics of ${\\cal N}=4$ SYM appears in elaborated dressing factors of the 2D two-particle scattering factors, all depending on the 'fundamental' one between two scalar excitations. From scattering factors we determine bound states. In particular, we study the strong coupling limit, in the non-perturbative, perturbative and giant hole regimes. Eventually, from these scattering data we construct the $4D$ pentagon transition amplitudes (perturbative regime). In this manner, we detail the multi-particle contributions (flux tube) to the MHV gluon scattering amplitudes/Wilson loops (OPE or BSV series) and re-sum them to the Thermo...

  11. Anti-ulcer activity of Synadenium grantii latex

    Directory of Open Access Journals (Sweden)

    Larissa L. G. Costa

    2012-10-01

    Full Text Available Synadenium grantii Hook f., Euphorbiaceae, is popularly known as leitosinha or janaúba. The diluted latex (18 drops/L of water is commonly used in the south of Brazil to treat gastric disturbances. This study evaluated phytochemical screening and toxicity using Artemia salina Leach of crude bark extract and also latex. The toxicity and the anti-ulcer activity of S. grantii latex were also tested in rats. Phytochemical results showed presence of tannins, terpenes, unsaponificable substances, coumarins and anthraquinones in the crude bark extract and terpenes in the latex. Gas chromatography-mass spectrometry (GC-MS analysis demonstrated the presence of diterpene tigliane esters in the latex, identified as 12-deoxyphorbol-13-(2-metilpropionate and phorbol 12,13,20-triacetate. The toxicity results using A. salina presented CL50 26.58μg/mL and CL50 778.66μg/mL, for the latex and the crude bark extract respectively. The toxicological hepatic parameters of the diluted latex were not different to the control group (p<0.05. The eosinophils cells showed an increase in both the diluted and pure latex groups. The pure latex showed gastric protection of 90% (p<0.05 and the diluted latex showed 6% compared to the negative control. Therefore, our data indicate that S. grantii latex, under research conditions presented gastric protection. Pure latex showed more toxicity than the diluted latex.

  12. Thermodynamics of polymer nematics described with a worm-like chain model: particle-based simulations and SCF theory calculations

    Science.gov (United States)

    Greco, Cristina; Yiang, Ying; Kremer, Kurt; Chen, Jeff; Daoulas, Kostas

    Polymer liquid crystals, apart from traditional applications as high strength materials, are important for new technologies, e.g. Organic Electronics. Their studies often invoke mesoscale models, parameterized to reproduce thermodynamic properties of the real material. Such top-down strategies require advanced simulation techniques, predicting accurately the thermodynamics of mesoscale models as a function of characteristic features and parameters. Here a recently developed model describing nematic polymers as worm-like chains interacting with soft directional potentials is considered. We present a special thermodynamic integration scheme delivering free energies in particle-based Monte Carlo simulations of this model, avoiding thermodynamic singularities. Conformational and structural properties, as well as Helmholtz free energies are reported as a function of interaction strength. They are compared with state-of-art SCF calculations invoking a continuum analog of the same model, demonstrating the role of liquid-packing and fluctuations.

  13. Designing a Multistage Supply Chain in Cross-Stage Reverse Logistics Environments: Application of Particle Swarm Optimization Algorithms

    Directory of Open Access Journals (Sweden)

    Tzu-An Chiang

    2014-01-01

    Full Text Available This study designed a cross-stage reverse logistics course for defective products so that damaged products generated in downstream partners can be directly returned to upstream partners throughout the stages of a supply chain for rework and maintenance. To solve this reverse supply chain design problem, an optimal cross-stage reverse logistics mathematical model was developed. In addition, we developed a genetic algorithm (GA and three particle swarm optimization (PSO algorithms: the inertia weight method (PSOA_IWM, VMax method (PSOA_VMM, and constriction factor method (PSOA_CFM, which we employed to find solutions to support this mathematical model. Finally, a real case and five simulative cases with different scopes were used to compare the execution times, convergence times, and objective function values of the four algorithms used to validate the model proposed in this study. Regarding system execution time, the GA consumed more time than the other three PSOs did. Regarding objective function value, the GA, PSOA_IWM, and PSOA_CFM could obtain a lower convergence value than PSOA_VMM could. Finally, PSOA_IWM demonstrated a faster convergence speed than PSOA_VMM, PSOA_CFM, and the GA did.

  14. Designing a multistage supply chain in cross-stage reverse logistics environments: application of particle swarm optimization algorithms.

    Science.gov (United States)

    Chiang, Tzu-An; Che, Z H; Cui, Zhihua

    2014-01-01

    This study designed a cross-stage reverse logistics course for defective products so that damaged products generated in downstream partners can be directly returned to upstream partners throughout the stages of a supply chain for rework and maintenance. To solve this reverse supply chain design problem, an optimal cross-stage reverse logistics mathematical model was developed. In addition, we developed a genetic algorithm (GA) and three particle swarm optimization (PSO) algorithms: the inertia weight method (PSOA_IWM), V(Max) method (PSOA_VMM), and constriction factor method (PSOA_CFM), which we employed to find solutions to support this mathematical model. Finally, a real case and five simulative cases with different scopes were used to compare the execution times, convergence times, and objective function values of the four algorithms used to validate the model proposed in this study. Regarding system execution time, the GA consumed more time than the other three PSOs did. Regarding objective function value, the GA, PSOA_IWM, and PSOA_CFM could obtain a lower convergence value than PSOA_VMM could. Finally, PSOA_IWM demonstrated a faster convergence speed than PSOA_VMM, PSOA_CFM, and the GA did.

  15. Ground State Geometries of Polyacetylene Chains from Many-Particle Quantum Mechanics.

    Science.gov (United States)

    Barborini, Matteo; Guidoni, Leonardo

    2015-09-08

    Due to the crucial role played by electron correlation, the accurate determination of ground state geometries of π-conjugated molecules is still a challenge for many quantum chemistry methods. Because of the high parallelism of the algorithms and their explicit treatment of electron correlation effects, Quantum Monte Carlo calculations can offer an accurate and reliable description of the electronic states and of the geometries of such systems, competing with traditional quantum chemistry approaches. Here, we report the structural properties of polyacetylene chains H-(C₂H₂)(N)-H up to N = 12 acetylene units, by means of Variational Monte Carlo (VMC) calculations based on the multi-determinant Jastrow Antisymmetrized Geminal Power (JAGP) wave function. This compact ansatz can provide for such systems an accurate description of the dynamical electronic correlation as recently detailed for the 1,3-butadiene molecule [J. Chem. Theory Comput. 2015 11 (2), 508-517]. The calculated Bond Length Alternation (BLA), namely the difference between the single and double carbon bonds, extrapolates, for N → ∞, to a value of 0.0910(7) Å, compatible with the experimental data. An accurate analysis was able to distinguish between the influence of the multi-determinantal AGP expansion and of the Jastrow factor on the geometrical properties of the fragments. Our size-extensive and self-interaction-free results provide new and accurate ab initio references for the structures of the ground state of polyenes.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Rumin, E-mail: wangmin19@mail.nwpu.edu.cn [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Zheng, Shuirong [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Northwestern Polytechnical University–East China University of Science and Technology Combined Research Institute of New High Speed Railway Materials (China); Farhan, Shameel; Yao, Hao; Jiang, Hao [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China)

    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}.

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

    Science.gov (United States)

    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...

  18. LaTeX for Agricultural Extension Professionals

    Science.gov (United States)

    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 ...

  19. Cationic polyelectrolyte functionalized magnetic particles assisted highly sensitive pathogens detection in combination with polymerase chain reaction and capillary electrophoresis.

    Science.gov (United States)

    Chen, Jia; Lin, Yuexin; Wang, Yu; Jia, Li

    2015-06-01

    Pathogenic bacteria cause significant morbidity and mortality to humans. There is a pressing need to establish a simple and reliable method to detect them. Herein, we show that magnetic particles (MPs) can be functionalized by poly(diallyl dimethylammonium chloride) (PDDA), and the particles (PDDA-MPs) can be utilized as adsorbents for capture of pathogenic bacteria from aqueous solution based on electrostatic interaction. The as-prepared PDDA-MPs were characterized by Fourier-transform infrared spectroscopy, zeta potential, vibrating sample magnetometry, X-ray diffraction spectrometry, scanning electron microscopy, and transmission electron microscopy. The adsorption equilibrium time can be achieved in 3min. According to the Langmuir adsorption isotherm, the maximum adsorption capacities for E. coli O157:H7 (Gram-negative bacteria) and L. monocytogenes (Gram-positive bacteria) were calculated to be 1.8×10(9) and 3.1×10(9)cfumg(-1), respectively. The bacteria in spiked mineral water (1000mL) can be completely captured when applying 50mg of PDDA-MPs and an adsorption time of 5min. In addition, PDDA-MPs-based magnetic separation method in combination with polymerase chain reaction and capillary electrophoresis allows for rapid detection of 10(1)cfumL(-1) bacteria.

  20. In vitro Transient Expression System of Latex C-serum was used for Analysis of Hevein Promoter in Response to Abscisic Acid in Hevea brasiliensis

    Institute of Scientific and Technical Information of China (English)

    Xiao-Wen Fei; Xiao-Dong Deng

    2008-01-01

    Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5' upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5' end nested deletion method in the present study, fused with a uidA (gus) gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from -749 to -292 was sufficient for expression of gus gene in latex, and the fragment from -292 to -168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus-specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from -749 to -292 was laticiferous-specific.

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

    Science.gov (United States)

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

    1994-01-01

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

  2. Synthesis and Characterization of Poly(St-co-BA) Latex with an Organic-Inorganic Hybrid Compound as Emulsifier

    Institute of Scientific and Technical Information of China (English)

    袁俊杰; 周树学; 廖建和; 武利民

    2003-01-01

    A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were a~:tually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.

  3. Experimental modeling of polymer latex spray coating for producing controlled-release urea

    Institute of Scientific and Technical Information of China (English)

    Rui Lan; Yonghui Liu; Guanda Wang; Tingjie Wang; Chengyou Kan; Yong Jin

    2011-01-01

    Spray coating of polymer latex onto fertilizer particles in a fluidized bed for producing controlled-release urea is an environment friendly technology as it does not need any toxic organic solvent.Since the spray coating process in a fluidized bed occurs in the presence of particle collisions,the coating of the particles is random,intermittent and multiple,thus making it difficult to investigate the film formation process.In this paper,an experimental model apparatus was designed and used to investigate the effects of the key factors in the spray coating process.This apparatus reasonably simplified the complex process to avoid particle collisions and randomness in the coating.The intermittent coating in the fluidized bed was modeled by periodic coating and dewatering in the experimental apparatus.A large area film was obtained,and the film permeability was measured.The effects of atomizing gas flow rate,spray rate of latex,solid content of latex and gas temperature on film structure and film permeability were investigated.It was found that water transfer played a dominant role in the spray coating process.

  4. Application of recombinant latex allergens in diagnostics of occupational latex allergy

    Directory of Open Access Journals (Sweden)

    Ewa Nowakowska-Świrta

    2015-02-01

    Full Text Available Over many years, allergy to natural rubber latex has been a major problem among health care workers (HCW. The diagnosis of occupational allergy requires methods of high diagnostic accuracy in view of certification implications (e.g., a sick worker quits a job. With the development of molecular methods, the frequency of application of recombinant allergens in the diagnostics of allergic diseases continues to increase. This paper reviews the applicability of laboratory tests which use recombinant allergens in the diagnostics of occupational allergy. The diagnosis of latex allergy is based on the presence of clinical symptoms linked with exposure to latex allergens, positive skin prick tests and detection of specific IgE antibodies to latex in serum. Moreover, in some cases specific challenge tests are conducted. The analysis of literature indicates that applying the panel of recombinant latex allergens in diagnostic tests, cross-reactivity can very likely be excluded and/or sensitization can be confirmed without the need for specific challenge tests, which in case of latex allergens carries a potential risk of generalized reactions. Med Pr 2015;66(1:85–97

  5. From polymer latexes to multifunctional liquid marbles.

    Science.gov (United States)

    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.

  6. Latex allergy in dentistry: clinical cases report

    NARCIS (Netherlands)

    Raggio, D.P.; Camargo, L.B.; Naspitz, G.M.C.C.; Politano, G.T.; Bonifacio, C.C.; Mendes, F.M.; Kierstman, F.

    2010-01-01

    Generally natural rubber latex (NRL) allergy is detected after some exposition to the material. As NRL is commonly found in different materials used daily in dental clinic, the allergy can be manifested in the pediatric dentistry clinic. The first clinical manifestation can be smooth but also severe

  7. PMMA-N,N,N-trimethyl chitosan nanoparticles for fabrication of antibacterial natural rubber latex gloves.

    Science.gov (United States)

    Arpornwichanop, Thanida; Polpanich, Duangporn; Thiramanas, Raweewan; Suteewong, Teeraporn; Tangboriboonrat, Pramuan

    2014-08-30

    This paper presents one-pot synthesis of N,N,N-trimethyl chitosan (TMC) stabilized poly(methyl methacrylate) (PMMA) latex particles via the miniemulsion polymerization technique. From (1)H NMR, synthesized TMC contains 52% degree of quaternization. Compared to native biopolymer chitosan, TMC possesses permanently positive charges as well as provides greater antibacterial activity. Combining properties of PMMA and TMC, PMMA-TMC latex nanoparticles (hydrodynamic size ≈282 nm) could be used in place of inorganic lubricating powder in fabrication of latex gloves at pH ≥ 7. After immersing sulphur prevulcanized natural rubber (SPNR) film into 3 wt% of PMMA-TMC latex at pH 7, significant amount of nanoparticles uniformly deposited onto SPNR film was observed under SEM. A number of nanoparticles present on film surface would increase surface roughness of the rubber film and potentially inhibit the bacterial (Escherichia coli and Staphylococcus aureus) growth, which would be useful for fabrication of special gloves with antibacterial property.

  8. Concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers in sinking particles south of Java

    Science.gov (United States)

    Chen, Wenwen; Mohtadi, Mahyar; Schefuß, Enno; Mollenhauer, Gesine

    2016-06-01

    In this study, we obtained concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) in a one-year time-series of sinking particles collected with a sediment trap moored from December 2001 to November 2002 at 2200 m water depth south of Java in the eastern Indian Ocean. We investigate the seasonality of alkenone and GDGT fluxes as well as the potential habitat depth of the Thaumarchaeota producing the GDGTs entrained in sinking particles. The alkenone flux shows a pronounced seasonality and ranges from 1 μg m-2 d-1 to 35 μg m-2 d-1. The highest alkenone flux is observed in late September during the Southeast monsoon, coincident with high total organic carbon fluxes as well as high net primary productivity. Flux-weighted mean temperature for the high flux period using the alkenone-based sea-surface temperature (SST) index U37K‧ is 26.7 °C, which is similar to satellite-derived Southeast (SE) monsoon SST (26.4 °C). The GDGT flux displays a weaker seasonality than that of the alkenones. It is elevated during the SE monsoon period compared to the Northwest (NW) monsoon and intermonsoon periods (approximately 2.5 times), which is probably related to seasonal variation of the abundance of Thaumarchaeota, or to enhanced export of GDGTs by aggregation with sinking phytoplankton detritus. Flux-weighted mean temperature inferred from the GDGT-based TEX86H index is 26.2 °C, which is 1.8 °C lower than mean annual (ma) SST but similar to SE monsoon SST. As the time series of TEX86H temperature estimates, however, does not record a strong seasonal amplitude, we infer that TEX86H reflects ma upper thermocline temperature at approximately 50 m water depth.

  9. Triterpenoid biosynthesis in Euphorbia lathyris latex

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Polystyrene latex separations by continuous flow electrophoresis on the Space Shuttle

    Science.gov (United States)

    Snyder, R. S.; Rhodes, P. H.; Miller, T. Y.; Micale, F. J.; Mann, R. V.

    1986-01-01

    The seventh mission of the Space Shuttle carried two NASA experiments in the McDonnell Douglas Astronautics Corporation continuous flow electrophoresis system. The objectives were to test the operation of continuous flow electrophoresis in a reduced gravity environment using stable particles with established electrokinetic properties and specifically to evaluate the influence of the electrical properties of the sample constituents on the resolution of the continuous flow electrophoretic device. Polystrene latex microspheres dispersed in a solution with three times the electrical conductivity of the curtain buffer separated with a significantly larger band spread compared to the second experiment under matched conductivity conditions. It is proposed that the sample of higher electrical conductivity distorted the electric field near the sample stream so that the polystyrene latex particles migrated toward the chamber walls where electroosmosis retarded and spread the sample.

  11. Production of Natural Rubber Grafted Styrene Copolymer Latex as Water Base Coatings

    Directory of Open Access Journals (Sweden)

    M Utama

    2006-07-01

    Full Text Available Twelve kinds formulation of natural rubber grafted copolymer styrene (NR-g-S prepared by gamma radiation co-polymerization technique has been carried out. The characteristic of NR-g-S and its water base coating such as molecular structure, particle size, and the properties of latex and its film were evaluated. The results showed that the NR-g-S latex as a water base coating has low viscosity, height strength, good grease resistance, good flexibility, good aging and corrosion resistance on concrete cement and metal. The average particle size is between 270-300 nm, and the bonding between poly-isoprene of NRL and styrene molecules were grafted copolymer

  12. INFLUENCE OF THE VOLATILE FATTY ACID CONTENT TO RADIATION VULCANIZED NATURAL RUBBER LATEX (RVNRL

    Directory of Open Access Journals (Sweden)

    CHIRINOS, Hugo David

    2012-01-01

    Full Text Available Natural rubber latex is a dispersion of natural rubber particles in water. These particles are coated with aprotein layer which will stabilize the dispersion in water by forming an electric charge in the layer. Any differentcondition affecting this layer disturbs the stability of dispersion. Microorganism attack disturbs the protein layerand consequently the stability of the dispersion. By adding 1.2% by weight of NH3, the stability of the dispersioncan be improved. The fresh latex was irradiated by Co-60 with irradiation dose of 10, 20, 30, 40 and 100 kGy.The results showed a relationship between the volatile fatty acid content (VFA, product from microorganismattack on carbohydrate and the green strength or the physical properties of vulcanized film. Low VFA numbershowing a higher physical strength of the film either un-vulcanized or vulcanized. It appeared that the structurewas responsible in yielding a good physical property of the film.

  13. High solids content, soap-free, film-forming latexes stabilized by laponite clay platelets.

    Science.gov (United States)

    Bourgeat-Lami, Elodie; Guimarães, Thiago Rodrigues; Pereira, Ana Maria Cenacchi; Alves, Gizelda Maria; Moreira, José Carlos; Putaux, Jean-Luc; Dos Santos, Amilton Martins

    2010-11-01

    High solids content film-forming poly[styrene-co-(n-butyl acrylate)] [poly(Sty-co-BuA)] latexes armored with Laponite clay platelets have been synthesized by soap-free emulsion copolymerization of styrene and n-butyl acrylate. The polymerizations were performed in batch in the presence of Laponite and a methyl ether acrylate-terminated poly(ethylene glycol) macromonomer in order to promote polymer/clay association. The overall polymerization kinetics showed a pronounced effect of clay on nucleation and stabilization of the latex particles. Cryo-transmission electron microscopy observation confirmed the armored morphology and indicated that the majority of Laponite platelets were located at the particle surface. The resulting nanostructured films displayed enhanced mechanical properties.

  14. Influence of viscoelasticity on the nano-micromechanical behavior of latex films and pigmented coatings

    Science.gov (United States)

    Giri, Manish

    2001-09-01

    Nano to microscale deformation behavior of different carboxylated styrene-butadiene co-polymer Latexes were investigated using a commercial nanoindentation device. The latexes differed primarily in their glass transition temperature (T g). The bulk dynamic rheological properties, as determined from a rheometer, dictate the axismmetric deformation behavior of the latexes. Results from dynamic tests performed on latexes were analyzed using the theories in contact and fracture mechanics. Two theories of linear viscoelastic fracture mechanics (LVEFM) were employed to model the adhesion hysteresis (loading-unloading cycle) curves to obtain meaningful cohesive zone (fracture process zone) parameters and a stress intensity functional (K I(t)) for an entire cycle. The stress intensity functional, extracted from the deformation behavior, is independent of the loading history and was shown to depend only on the crack propagation velocity, (da/dt), for the entire cycle. The quantitative values of stress intensities were then discussed in the light of polymer molecular phenomenon's such as viscous chain desorption. Nanoindetation was developed as a tool for systematically investigating both the bulk as well as the cohesive zone properties of viscoelastic polymers. Effect of plastic deformation on the deformation behavior of high pigment volume concentration (PVC) coatings was also analyzed. Polystyrene plastic pigment, CaCO3 and Clay pigments were used to form the coatings layers. High PVC coatings are viscoelastic due to the latex present but also contain air, the third phase, which could explain the plastic deformation if a certain critical yield stress is exceeded. At PVC's greater than 70%, the coatings showed significant plastic (permanent) deformation, which has to be accounted for in modeling the hysteresis curves. The residual plastic deformation was confirmed by imaging the indent over a period of time. Modeling the curves resulted in a compressive yield stress (sigma

  15. Assimilation of Satellite Soil Moisture observation with the Particle Filter-Markov Chain Monte Carlo and Geostatistical Modeling

    Science.gov (United States)

    Moradkhani, Hamid; Yan, Hongxiang

    2016-04-01

    Soil moisture simulation and prediction are increasingly used to characterize agricultural droughts but the process suffers from data scarcity and quality. The satellite soil moisture observations could be used to improve model predictions with data assimilation. Remote sensing products, however, are typically discontinuous in spatial-temporal coverages; while simulated soil moisture products are potentially biased due to the errors in forcing data, parameters, and deficiencies of model physics. This study attempts to provide a detailed analysis of the joint and separate assimilation of streamflow and Advanced Scatterometer (ASCAT) surface soil moisture into a fully distributed hydrologic model, with the use of recently developed particle filter-Markov chain Monte Carlo (PF-MCMC) method. A geostatistical model is introduced to overcome the satellite soil moisture discontinuity issue where satellite data does not cover the whole study region or is significantly biased, and the dominant land cover is dense vegetation. The results indicate that joint assimilation of soil moisture and streamflow has minimal effect in improving the streamflow prediction, however, the surface soil moisture field is significantly improved. The combination of DA and geostatistical approach can further improve the surface soil moisture prediction.

  16. Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Polymerase chain reaction (PCR) was used to amplify a 600-base pair (bp) sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil (Alfisol) and Red soil (Ultisol), and three different minerals (goethite, kaolinite, montmorillonite). DNA bound on soil colloids, kaolinite, and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted, 10- and 20-fold. The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected. DNA bound on goethite was amplified irrespective of whether the complex was used directly, or diluted 10- and 20-fold. The amplification of mineral-bound plasmid DNA by PCR is, therefore, markedly influenced by the type and concentration of minerals used. This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.

  17. Trapping and chaining self-assembly of colloidal polystyrene particles over a floating electrode by using combined induced-charge electroosmosis and attractive dipole-dipole interactions.

    Science.gov (United States)

    Liu, Weiyu; Shao, Jinyou; Jia, Yankai; Tao, Ye; Ding, Yucheng; Jiang, Hongyuan; Ren, Yukun

    2015-11-01

    We propose a novel low-frequency strategy to trap 10 μm colloidal polystyrene (PS) particles of small buoyancy velocity on the surface of a floating electrode, on the basis of combined induced-charge electroosmotic (ICEO) flow and dipole-dipole chaining phenomenon. For field frequencies of 5-50 Hz, much lower than the reciprocal RC time scale, double-layer polarization makes electric field lines pass around the 'insulating' surface of the ideally polarizable floating electrode. Once the long-range ICEO convective micro-vortexes transport particles quickly from the bulk fluid to the electrode surface, neighbouring particles aligned along the local horizontal electric field attract one another by attractive dipolar interactions, and form arrays of particle chains that are almost parallel with the applied electric field. Most importantly, this low-frequency trapping method takes advantage of the dielectrophoretic (DEP) particle-particle interaction to enhance the downward buoyancy force of this dipolar chaining assembly structure, in order to overcome the upward ICEO fluidic drag and realize stable particle trapping around the flow stagnation region. For the sake of comparison, the field frequency is further raised far above the DC limit. At the intermediate frequencies of 200 Hz-2 kHz, this trapping method fails to work, since the normal electric field component emanates from the conducting electrode surface. Besides, at high field frequencies (>3 kHz), particles can be once again effectively trapped at the electrode center, though with a compact (3 kHz) or disordered (10 kHz) 2D packing state on the electrode surface and mainly governed by the short-range negative DEP force field, resulting in requiring a much longer trapping time. To gain a better interpretation of the various particle behaviours observed in experiments, we develop a theoretical framework that takes into account both Maxwell-Wagner interfacial charge relaxation at the particle

  18. The patatin-like protein from the latex of Hevea brasiliensis (Hev b 7) is not a vacuolar protein

    NARCIS (Netherlands)

    Jekel, PA; Hofsteenge, J; Beintema, JJ

    2003-01-01

    Upon centrifugation, rubber latex is divided into a layer of rubber particles, the cytosol, and the lutoid-body fraction, which is of vacuolar origin. One of the proteins isolated from the lutoid-body fraction is a protein with a molecular mass of 43 kDa, which has esterase activity on p-nitrophenyl

  19. The spectra of stimulated concentration scattering (Mie scattering) on nanoparticles latex suspension in the presence of convection

    Science.gov (United States)

    Burkhanov, I. S.; Krivokhizha, S. V.; Chaikov, L. L.

    2016-09-01

    Spectral shifts of the stimulated concentration light scattering (SCLS, stimulated Mie scattering) in suspensions of various sized latex nanoparticles in water were measured by the light guide scheme in conditions of the backscattering in the presence of convection. It is shown that the spectral shift can be either negative or positive depending on the particle size.

  20. Larvicidal activity of silver nanoparticles synthesized using Plumeria rubra plant latex against Aedes aegypti and Anopheles stephensi.

    Science.gov (United States)

    Patil, Chandrashekhar D; Patil, Satish V; Borase, Hemant P; Salunke, Bipinchandra K; Salunkhe, Rahul B

    2012-05-01

    In the present study activity of silver nanoparticles (AgNPs) synthesized using Plumeria rubra plant latex against second and fourth larval instar of Aedes aegypti and Anopheles stephensi was determined. Range of concentrations of synthesized AgNps (10, 5, 2.5, 1.25, 0.625, 0.3125 ppm) and aqueous crude latex (1,000, 500, 250, 125, 62.50, 31.25 ppm) were tested against larvae of A. aegypti and A. Stephensi. The synthesized AgNps from P. rubra latex were highly toxic than crude latex extract in both mosquito species. The LC(50) values for second and fourth larval instars after 24 h of crude latex exposure were 1.49, 1.82 ppm against A. aegypti and 1.10, 1.74 ppm against A. stephensi respectively. These figures were 181.67, 287.49 ppm against A. aegypti and 143.69, 170.58 ppm against A. stephensi respectively for crude latex extract. The mortality rates were positively correlated with the concentration of AgNPs. The characterization studies of synthesized AgNPs by UV-Vis spectrophotometry, transmission electron microscopy (TEM), Particle size analysis (PSA) and zeta potential confirmed the spherical shape and size (32-200 nm) of silver nanoparticles along with stability. Toxicity studies carried out against non-target fish species Poecilia reticulata, the most common organism in the habitats of A. aegypti and A. stephensi showed no toxicity at LC(50) and LC(90) doses of the AgNPs. This is the first report on mosquito larvicidal activity of latex synthesized nanoparticles.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Agarwal, Sanjay; Gawkrodger, David J

    2002-01-01

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

  3. ADVERSE REACTION TO LATEX CONTAINING MATERIALS IN HEALTH CARE WORKERS

    Directory of Open Access Journals (Sweden)

    Gh. Pouryaghoub

    2008-04-01

    Full Text Available Latex allergy has become an occupational hazard among healthcare workers. Atopy, intensity and duration of exposure have been recognized as predisposing factors for latex sensitization. Frequency of sensitization varies among countries. So we decided to investigate the prevalence of latex sensitization and potential risk factors among healthcare workers in a general hospital. In a cross sectional study by distributing a questionnaire among 876 employees of a general hospital, we investigated the prevalence of latex allergy and the potential risk factors for latex sensitization. We collected information about occupational history, including specific tasks performed, time of first exposure to latex, number of pairs of gloves used, and duration of weekly exposure. We also investigated the interval between first exposure and onset of symptoms. We asked about pre-existing rhinoconjuctivitis, asthma, atopic and contact dermatitis, hay fever, autoimmune diseases, and food allergies. This survey documented a high prevalence of adverse reaction to all latex containing materials (52.5%. 37.7% of responder had adverse reaction to latex gloves. The highest prevalence of adverse reaction to all latex containing materials was found in the surgical operating room, followed by emergency unit and internal medicine wards. According to this study, frequency of adverse reaction to latex was high among health care workers. This may be due to relatively low response rate, low quality of latex products in Iran, and the method of measurement. Whenever, the need for implementing prevention program, using latex-free methods and training of employees to reduce adverse reaction to latex is apparent.

  4. Proteolytic properties of Funastrum clausum latex.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Anthelmintic activity of latex of Jatropha curcas (ratanjot

    Directory of Open Access Journals (Sweden)

    Mr. Hitesh Kumar Parmar

    2014-03-01

    Full Text Available A multitude of plants have been used for the treatment of helmenthiasis throughout the world. One such plant is Jatropha curcas. It is known as ratanjot or biodiesel plant, which belongs to the family Euphorbiaceae. It possesses many uses like antidiabetic, antmicrobial and antioxidant. The phytochemical prospection of the fresh and dried latex showed the presence of different classes of secondary metabolites that have demonstrated antimicrobial action. The present research work investigated the Anthelmintic activity of latex of leaves of Jatropha curcas. The major finding of the present work illustrates that aqueous latex of Jatropha curcas has shown better Anthelmintic activity than control Jatropha latex and standard drug, piperazine citrate.

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

    Science.gov (United States)

    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.

  8. Study on radiation vulcanization of natural rubber latex

    Institute of Scientific and Technical Information of China (English)

    ZhuNan-Kang; MakuuchiK; 等

    1997-01-01

    The effect of dose rate of 60Co γ-ray on radiation vulacnization of natural rubber latex is studied using Malysian latex with 0.002 mass fraction KOH and 0.05 mass fraction n-BA.Results show that,when radiation doses are 20 and 15kGy,only that the dose rates are greater than 0.49 and 1.6 kGY/h,respectively can make the tensile strength of latex film meet the related standard;besides,storage time of radiation vulcanization latex has no effect on physical properties of the film.

  9. Whole-transcriptome survey of the putative ATP-binding cassette (ABC) transporter family genes in the latex-producing laticifers of Hevea brasiliensis.

    Science.gov (United States)

    Zhiyi, Nie; Guijuan, Kang; Yu, Li; Longjun, Dai; Rizhong, Zeng

    2015-01-01

    The ATP-binding cassette (ABC) proteins or transporters constitute a large protein family in plants and are involved in many different cellular functions and processes, including solute transportation, channel regulation and molecular switches, etc. Through transcriptome sequencing, a transcriptome-wide survey and expression analysis of the ABC protein genes were carried out using the laticiferous latex from Hevea brasiliensis (rubber tree). A total of 46 putative ABC family proteins were identified in the H. brasiliensis latex. These consisted of 12 'full-size', 21 'half-size' and 13 other putative ABC proteins, and all of them showed strong conservation with their Arabidopsis thaliana counterparts. This study indicated that all eight plant ABC protein paralog subfamilies were identified in the H. brasiliensis latex, of which ABCB, ABCG and ABCI were the most abundant. Real-time quantitative reverse transcription-polymerase chain reaction assays demonstrated that gene expression of several latex ABC proteins was regulated by ethylene, jasmonic acid or bark tapping (a wound stress) stimulation, and that HbABCB15, HbABCB19, HbABCD1 and HbABCG21 responded most significantly of all to the abiotic stresses. The identification and expression analysis of the latex ABC family proteins could facilitate further investigation into their physiological involvement in latex metabolism and rubber biosynthesis by H. brasiliensis.

  10. Whole-transcriptome survey of the putative ATP-binding cassette (ABC transporter family genes in the latex-producing laticifers of Hevea brasiliensis.

    Directory of Open Access Journals (Sweden)

    Nie Zhiyi

    Full Text Available The ATP-binding cassette (ABC proteins or transporters constitute a large protein family in plants and are involved in many different cellular functions and processes, including solute transportation, channel regulation and molecular switches, etc. Through transcriptome sequencing, a transcriptome-wide survey and expression analysis of the ABC protein genes were carried out using the laticiferous latex from Hevea brasiliensis (rubber tree. A total of 46 putative ABC family proteins were identified in the H. brasiliensis latex. These consisted of 12 'full-size', 21 'half-size' and 13 other putative ABC proteins, and all of them showed strong conservation with their Arabidopsis thaliana counterparts. This study indicated that all eight plant ABC protein paralog subfamilies were identified in the H. brasiliensis latex, of which ABCB, ABCG and ABCI were the most abundant. Real-time quantitative reverse transcription-polymerase chain reaction assays demonstrated that gene expression of several latex ABC proteins was regulated by ethylene, jasmonic acid or bark tapping (a wound stress stimulation, and that HbABCB15, HbABCB19, HbABCD1 and HbABCG21 responded most significantly of all to the abiotic stresses. The identification and expression analysis of the latex ABC family proteins could facilitate further investigation into their physiological involvement in latex metabolism and rubber biosynthesis by H. brasiliensis.

  11. Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

    Directory of Open Access Journals (Sweden)

    Bérangère Bailly

    2006-01-01

    Full Text Available Polystyrene (PS chains with molecular weights comprised between 8000 and 64000 g⋅mol-1 and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and Stöber silica, resp. through nitroxide-mediated polymerization (NMP. Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted Stöber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

  12. Follow-up Study of Latex-allergic Health Care Workers in Japan

    Directory of Open Access Journals (Sweden)

    Akiko Yagami

    2006-01-01

    Conclusions: After avoiding latex products and following our educational suggestions, the patients' allergy symptoms had generally improved. This indicates that our countermeasures against latex allergy were largely successful.

  13. Effect of SiO2 Particle Size and Length of Poly(Propylene Glycol Chain on Rheological Properties of Shear Thickening Fluids

    Directory of Open Access Journals (Sweden)

    Antosik A.

    2016-09-01

    Full Text Available The rheological properties of shear thickening fluids based on silica powder of particles size in range 0.10 – 2.80 μm and poly(propylene glycol of 425, 1000, 2000 g/mol molar mass were investigated. The effect of particle size and the length of the polymeric chain was considered. The objective of this study was to understand basic trends of physicochemical properties of used materials on the onset and the maximum of shear thickening and dilatant effect. Outcome of the research suggested that an increase in the particle size caused a decrease in dilatant effect and shift towards higher shear rate values. Application of carrier fluid of higher molar mass allowed to increase dilatant effect but it resulted in the increase of the initial viscosity of the fluid.

  14. A method for protein extraction from different subcellular fractions of laticifer latex in Hevea brasiliensis compatible with 2-DE and MS

    Directory of Open Access Journals (Sweden)

    Guo Anping

    2010-06-01

    Full Text Available Abstract Background Proteomic analysis of laticifer latex in Hevea brasiliensis has been received more significant attentions. However, the sticky and viscous characteristic of rubber latex as cytoplasm of laticifer cells and the complication of laticifer latex membrane systems has made it challenge to isolate high-quality proteins for 2-DE and MS. Results Based on the reported Borax/PVPP/Phenol (BPP protocol, we developed an efficient method for protein preparation from different latex subcellular fractions and constructed high-resolution reference 2-DE maps. The obtained proteins from both total latex and C-serum fraction with this protocol generate more than one thousand protein spots and several hundreds of protein spots from rubber particles as well as lutoid fraction and its membranes on the CBB stained 2-DE gels. The identification of 13 representative proteins on 2-DE gels by MALDI TOF/TOF MS/MS suggested that this method is compatible with MS. Conclusion The proteins extracted by this method are compatible with 2-DE and MS. This protein preparation protocol is expected to be used in future comparative proteomic analysis for natural rubber latex.

  15. Latex allergy in Bozyaka Social Security Hospital workers, Turkey

    Institute of Scientific and Technical Information of China (English)

    Kose Sukran; MandIraclo(g)glu Aliye

    2004-01-01

    @@ Latex glove used in healthcare settings has risen dramatically since around 1987. The increased threat of contracting HIV, hepatitis B, and other infectious agents during the course of delivering health care to patients has created the need for barrier protection. 1 Studies have estimated that the prevalence of latex allergy in healthcare workers ranged from 2.9% up to 17%.2

  16. Antimicrobial activity of latex silver nanoparticles using Calotropis procera

    Directory of Open Access Journals (Sweden)

    Nadia Hussein Mohamed

    2014-11-01

    Conclusions: It can be concluded that serum latex of Calotropis procera was found to display strong potential for the synthesis of AgNPs as antimicrobial agents through rapid reduction of silver ions (Ag+ to Ag0. The green synthesized AgNPs were found to show higher antimicrobial efficacy than crude latex.

  17. A comparison of different LaTeX programs

    NARCIS (Netherlands)

    Koning, Ruud H.

    2001-01-01

    In this review two commercial and two freeware LaTeX implementations are discussed and compared: teTeX (Linux, Unix) pcTeX32 (Windows 3.1, Windows95/98/NT) Scientific Workplace (Windows95/98/NT) mikTeX (Windows95/98/NT) Keywords: LaTeX, word processing

  18. Installing fonts in LaTeX a user's experience

    NARCIS (Netherlands)

    Hanssen, Ferdy

    2003-01-01

    This paper presents a user's experience with installing fonts for use in LaTeX. It will be shown that it is not hard to make a standard Type 1 font work, if you use modern font installation software for LaTeX. All the steps necessary to install the example fonts will be shown. The example fonts used

  19. Latex agglutination assays for detection of non-O157 Shiga toxin-producing Escherichia coli serogroups O26, O45, O103, O111, O121, and O145.

    Science.gov (United States)

    Medina, Marjorie B; Shelver, Weilin L; Fratamico, Pina M; Fortis, Laurie; Tillman, Glenn; Narang, Neelam; Cray, William C; Esteban, Emilio; Debroy, Andchitrita

    2012-05-01

    Latex agglutination assays utilizing polyclonal antibodies were developed for the top six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups. Rabbit antisera were affinity purified through protein A/G columns, and the isolated immunoglobulins (IgGs) were covalently immobilized onto polystyrene latex particles. The resulting latex-IgG complex had a protein (IgG) load of 0.20 to 0.28 mg/ml in a 1% latex suspension. Optimum conditions for the agglutination assay consisted of utilizing 20 μm l of latex-IgG reagent containing 2.0 to 2.8 μm g IgG in a 0.5% latex suspension. Agglutination or flocculation was observed almost instantly after mixing the colonies with the latex-IgG, indicating STEC strains. More than 100 target and nontarget strains were tested in more than 3,000 test replicates. All target organisms produced positive results, but three antisera (anti-O26, anti-O103, and anti-O145) cross-reacted with some other STECs. The anti-O103 and anti-O145 latex reagents cross-reacted with O26 strains, and the anti-O26 cross-reacted with O103 strains. The latex-IgG reagents are stable for at least 1 year and are easy to prepare. These agglutination assays can be used for identification of presumptive non-O157 STEC colonies from agar media. The techniques used to prepare the latex reagents also can be utilized for testing other STEC serogroups, other E. coli serotypes, or other pathogens to ensure safe foods to consumers.

  20. Polyphenoloxidase silencing affects latex coagulation in Taraxacum species.

    Science.gov (United States)

    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.

  1. Cytotoxicity Comparison of the Nanoparticles Deposited on Latex Rubber Bands between the Original and Stretched State

    Directory of Open Access Journals (Sweden)

    Jung-Hwan Lee

    2014-01-01

    Full Text Available Understanding the biocompatibility of nanoparticles in dental materials is essential for their safe usage in the oral cavity. In this study, we investigated whether nanoparticles deposited on orthodontic latex rubber bands are involved in the induction of cytotoxicity. A method of stretching to three times (“3L” the length of the latex rubber bands was employed to detach the particles using the original length (“L” for comparison. The cytotoxicity tests were performed on extracts with mouse fibroblasts (L929 and human gingival fibroblasts (HGFs. Fourier transform infrared spectroscopy, ion chromatography, elemental analysis, and inductively coupled plasma mass spectrometry (ICP-MS were performed to detect the harmful components in the extracts from rubber bands. There was a significant decrease in the cell viability in the “L” samples compared with the “3L” samples (P<0.05 in the L929 and HGF cells. This was due to the Ni single crystal nanoparticles (~50nm from the inner surface of “L” samples that were detached in the “3L” samples as well as the Zn ion (~9 ppm detected in the extract. This study revealed that the Ni nanoparticles, as well as Zn ions, were involved in the induction of cytotoxicity from the latex rubber bands.

  2. Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts.

    Science.gov (United States)

    Divry, V; Gromer, A; Nassar, M; Lambour, C; Collin, D; Holl, Y

    2016-07-14

    This article presents studies on the drying kinetics of latexes with particles made progressively softer by adding increasing amounts of a plasticizer, in relation to speeds of horizontal drying fronts and particle deformation mechanisms. Global drying rates were measured by gravimetry, and speeds of the horizontal fronts were recorded using a video camera and image processing. Particle deformation mechanisms were inferred using the deformation map established by Routh and Russel (RR). This required precise measurements of the rheological properties of the polymers using a piezorheometer. The results show that latexes with softer particles dry slowly, but in our systems, this is not due to skin formation. A correlation between global drying rates and speeds of horizontal fronts could be established and interpreted in terms of the evolution of mass transfer coefficients of water in different areas of the drying system. The speeds of the horizontal drying fronts were compared with the RR model. A remarkable qualitative agreement of the curve shapes was observed; however, the fit could not be considered good. These results call for further research efforts in modeling and simulation.

  3. Kinetics of successive seeding of monodisperse polystyrene latexes. I - Initiation via potassium persulfate. II - Azo initiators with and without inhibitors

    Science.gov (United States)

    Sudol, E. D.; El-Aasser, M. S.; Vanderhoff, J. W.

    1986-01-01

    The polymerization kinetics of monodisperse polystyrene latexes with diameters of 1 micron are studied. The monodisperse latexes were prepared by the successive seeding method using 1 mM K2S2O8 with an 8 percent emulsifier surface coverage and 0.5 mM K2S2O8 with a 4 percent emulsifier surface coverage, and the kinetics were measured in a piston/cylinder dialometer. The data reveal that the polymerization rate decreases with increasing particle size; and the surface charge decreases with increasing particle size. The effects of initiators (AIBN and AMBN) and inhibitors (NH24SCN, NaNO2, and hydroquinone) on the product monodispersity and polymerization kinetics of latexes with diameters greater than 1 micron are investigated in a second experiment. It is observed that hydroquinone combined with AMBN are most effective in reducing nucleation without causing flocculation. It is noted that the kinetic transition from emulsion to bulk is complete for a particle size exceeding 1 micron in which the polymerization rate is independent of the particle size.

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

    Science.gov (United States)

    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.

  5. Research progress of the modification of natural rubber latex%天然胶乳改性研究进展

    Institute of Scientific and Technical Information of China (English)

    刘东辉; 徐亚丽; 孟丽丰

    2012-01-01

    介绍了天然胶乳的特点,综述了天然胶乳填料改性(纳米粒子改性和非纳米粒子改性)及化学改性(氯化、环化、环氧化、接枝聚合)的研究进展,分析了目前天然胶乳改性存在的问题,并展望了未来的发展趋势.%The characteristics of natural rubber latex had been introduced. The research progress of modification on the natural rubber latex was reviewed. Filler modification (including nano-particles and other particles) and chemical modification (including chlorination, cyclization, epoxidation, graft polymerization) were all studied. The main problems that existed at present were analyzed,and finally the future research trend was prospected.

  6. Characterization of a detector chain using a FPGA-based time-to-digital converter to reconstruct the three-dimensional coordinates of single particles at high flux

    Energy Technology Data Exchange (ETDEWEB)

    Nogrette, F.; Chang, R.; Bouton, Q.; Westbrook, C. I.; Clément, D. [Laboratoire Charles Fabry, Institut d’Optique Graduate School, CNRS, Univ. Paris-Saclay, 91127 Palaiseau cedex (France); Heurteau, D.; Sellem, R. [Fédération de Recherche LUMAT (DTPI), CNRS, Univ. Paris-Sud, Institut d’Optique Graduate School, Univ. Paris-Saclay, F-91405 Orsay (France)

    2015-11-15

    We report on the development of a novel FPGA-based time-to-digital converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of micro-channel plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1 × 10{sup 6} s{sup −1} and three-dimensional reconstruction of the coordinates up to 3.2 × 10{sup 6} particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) μm at a flux of 3 × 10{sup 5} particles per second. In addition, we analyze a method to estimate the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work apply to the detection of other kinds of particles.

  7. Characterization of a detector chain using a FPGA-based time-to-digital converter to reconstruct the three-dimensional coordinates of single particles at high flux.

    Science.gov (United States)

    Nogrette, F; Heurteau, D; Chang, R; Bouton, Q; Westbrook, C I; Sellem, R; Clément, D

    2015-11-01

    We report on the development of a novel FPGA-based time-to-digital converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of micro-channel plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1 × 10(6) s(-1) and three-dimensional reconstruction of the coordinates up to 3.2 × 10(6) particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) μm at a flux of 3 × 10(5) particles per second. In addition, we analyze a method to estimate the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work apply to the detection of other kinds of particles.

  8. Effect of Polyvinylpyrrolidone on the Morphologies of Latex Films and Air Permeability of the Latex Finished Fabrics

    Institute of Scientific and Technical Information of China (English)

    SHEN Yi-feng; YE Jia-jia; YANG Lei; WU Ming-hua; NI Tian-xiang

    2010-01-01

    Low air permeability is a common problem happening to the coating finished and pigment dyed fabrics.To tackle the problem,styrene and butyl acrylate copolymer latex was prepared and used as substitute for the binder.Then,polyvinylpyrrolidoue(PVP)was fed into the latex.It was expected that pores could form in the resulting latex film after being rinsed.The morphologies of the latex films were analysized by scanning electric microscope(SEM).It was found that the continuity of the latex films decreased greatly because of the addition of PVP,leading to the loss of the stress at break of the films.After rinsing with methanol aqueous solution,PVP was easily leached off and(macro)void was formed in the latex films.The size of the void decreased with the increase of the PVP concentration.Then,the latex with and without PVP was used to finish the cotton fabrics and engaged as binder in pigment dyeing.After PVP was rinsed out,the air permeability of the fabrics improved greatly,which recovered to that of the unfinished one.In the meantime,the color fastness to rubbing was little affected.So,the method of PVP addition could be termed as an efficient way to improve the air permeability in coating and dyeing industry.

  9. RAFT microemulsion polymerization with surface-active chain transfer agent

    Science.gov (United States)

    El-Hedok, Ibrahim Adnan

    The work described in this dissertation focuses on enhancing the polymer nanoparticle synthesis using RAFT (reversible-addition fragmentation chain transfer) in microemulsion polymerization in order to achieve predetermined molecular weight with narrow molecular weight polydispersity. The hypothesis is that the use of an amphiphilic chain transfer agent (surface-active CTA) will confine the CTA to the surface of the particle and thermodynamically favor partitioning of the CTA between micelles and particles throughout the polymerization. Thus, the CTA diffusion from micelles to polymer particles would be minimized and the breadth of the CTA per particle distribution would remain low. We report the successful improved synthesis of poly(butyl acrylate), poly(ethyl acrylate), and poly(styrene) nanoparticles using the RAFT microemulsion polymerization with surface-active CTA. The polymerization kinetics, polymer characteristics and latex size experimental data are presented. The data analysis indicates that the CTA remains partitioned between the micelles and particles by the end of the polymerization, as expected. We also report the synthesis of well-defined core/shell poly(styrene)/poly(butyl acrylate) nanoparticle, having polydispersity index value of 1.1, using semi-continuous microemulsion polymerization with the surface-active CTA. The surface-active CTA restricts the polymerization growth to the surface of the particle, which facilitates the formation of a shell block co-polymers with each subsequent second monomer addition instead of discrete homopolymers. This synthesis method can be used to create a wide range of core/shell polymer nanoparticles with well-defined morphology, given the right feeding conditions.

  10. Production of Gum from Cashew Tree Latex

    Directory of Open Access Journals (Sweden)

    O. S. AZEEZ

    2005-06-01

    Full Text Available This research is aimed at producing gum from cashew tree latex, which can act as substitute for gum Arabic. The method used include drying and size reduction of the exudates gum, sieving of the gum to remove impurities, dissolution of the gum in distilled water, filtration to remove polysaccharide waste and finally concentration and stability of the gum. Glycerine, starch and Zinc oxide are some of the additives used in stabilizing the gum. The pH and Viscosity on addition of various percentage concentration of stabilizing agent were determined. Gum of the best quality was obtained with viscosity and pH of 4.52 Ns/m2 and 4.2 respectively; this is because the natural pH of gum from Acacia Senegal ranges between 3.9 - 4.9. The gum can be used as an alternative for synthetic adhesive used presently for stamps and envelopes.

  11. Latex Dipping Machine PLC Control and Its Programming

    Directory of Open Access Journals (Sweden)

    Yimin Zhang

    2012-10-01

    Full Text Available Latex dipping machine is based on a latex patent products new-production condom and the development of the machine. The latex dipping agencies combined with production condom mechanism. First it realized a 3-dimensional accurate localization system using stepping motors. SIMATIC S7-200 series programmable controller, motion module EM253 and stepping motor are tied in wedlock to realize allocation of 3-dimension of X axis and Y axis and Z axis. Through the PTO pulse of Siemens S7-200 PLC controller and combined with the use of EM253 module, through the mould precise control programming soak glue and roll edge to achieve the control mold of rotation and swinging the uniform distributed latex. And the system has applied successfully in foreign-funded enterprise of Singapore.

  12. Coagulant and anticoagulant activities in Jatropha curcas latex.

    Science.gov (United States)

    Osoniyi, Omolaja; Onajobi, Funmi

    2003-11-01

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

  13. Tensile Strength of PHBV/Natural Rubber Latex Mixtures

    OpenAIRE

    Promkotra Sarunya; Kangsadan Tawiwan

    2015-01-01

    A polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is mingled with natural rubber latex (R) to develop its mechanical property of the blend. Normally, substantial effects of the PHBV are hard, fragile, and inelastic, whereas the natural rubber is represented itself as very high elastic matter. The mixtures between the PHBV and natural rubber latex (R) are considered in different proportions. The PHBV solutions (w/v) are defined suitability at 1% (P1), 2% (P2), and 3% (P3). Their liquid mixtures ...

  14. Properties of Polyacrylate Latex Prepared Under Different Emulsified Systems

    Institute of Scientific and Technical Information of China (English)

    CHEN Lijun; WU Fengqin

    2012-01-01

    The polyacrylate latexes were synthesized via pre-emulsified and semi-continuous seeded emulsion polymerization technology when conventional surfactant or polymerizable surfactant was used as emulsifiers.The resultant latexes and their films were characterized with the contact angle determinator and rheometer.Effect of the polymerizable surfactant on water resistance,stability and rheology of the latex was studied.Results show that the water resistance of film is increased first then decreased with the increase of the amount of the polymerizable surfactant.There exists the optimum value of the amount of the polymerizable surfactant for the water resistance of the film.In comparison with the latex prepared with the conventional surfactant,both the mechanical stability and the freezing-thaw stability of the latex are improved when the polymerizable surfactant is used during the course of the emulsion polymerization.The resultant latex has rheological properties of pseudo-plastic fluid and belongs to non-Newtonian fluid.

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

    Directory of Open Access Journals (Sweden)

    Raju Raghavan

    2007-01-01

    Full Text Available Abstract 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.

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

    Science.gov (United States)

    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.

  17. Characterization of a detector chain using a FPGA-based Time-to-Digital Converter to reconstruct the three-dimensional coordinates of single particles at high flux

    CERN Document Server

    Nogrette, F; Chang, R; Bouton, Q; Westbrook, C I; Sellem, R; Clément, D

    2015-01-01

    We report on the development of a novel FPGA-based Time-to-Digital Converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of Micro-Channel Plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1x10^6 per second and three-dimensional reconstruction of the coordinates up to 2.5x10^6 particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) um. In addition we analyze a method to measure the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work directly apply to the detection of other kinds of particles.

  18. 有机无机杂化物作乳化剂的苯丙乳液制备及其性能表征%Synthesis and Characterization of Poly(St-co-BA) Latex with an Organic-Inorganic Hybrid Compound as Emulsifier

    Institute of Scientific and Technical Information of China (English)

    袁俊杰; 周树学; 廖建和; 武利民

    2003-01-01

    A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound(OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particlesize analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamicmechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviouslyimprove the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhancethe store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHCcontent increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, andthese films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organicsilicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperaturethan organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.

  19. PEGylation of phytantriol-based lyotropic liquid crystalline particles--the effect of lipid composition, PEG chain length, and temperature on the internal nanostructure.

    Science.gov (United States)

    Nilsson, Christa; Østergaard, Jesper; Larsen, Susan Weng; Larsen, Claus; Urtti, Arto; Yaghmur, Anan

    2014-06-10

    Poly(ethylene glycol)-grafted 1,2-distearoyl-sn-glycero-3-phosphoethanolamines (DSPE-mPEGs) are a family of amphiphilic lipopolymers attractive in formulating injectable long-circulating nanoparticulate drug formulations. In addition to long circulating liposomes, there is an interest in developing injectable long-circulating drug nanocarriers based on cubosomes and hexosomes by shielding and coating the dispersed particles enveloping well-defined internal nonlamellar liquid crystalline nanostructures with hydrophilic PEG segments. The present study attempts to shed light on the possible PEGylation of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based on phytantriol (PHYT) were investigated by means of synchrotron small-angle X-ray scattering and Transmission Electron Cryo-Microscopy. The results suggest that the used lipopolymers are incorporated into the water-PHYT interfacial area and induce a significant effect on the internal nanostructures of the dispersed submicrometer-sized particles. The hydrophilic domains of the internal liquid crystalline nanostructures of these aqueous dispersions are functionalized, i.e., the hydrophilic nanochannels of the internal cubic Pn3m and Im3m phases are significantly enlarged in the presence of relatively small amounts of the used DSPE-mPEGs. It is evident that the partial replacement of PHYT by these PEGylated lipids could be an attractive approach for the surface modification of cubosomal and hexosomal particles. These PEGylated nanocarriers are particularly attractive in designing injectable cubosomal and hexosomal nanocarriers for loading drugs and/or imaging probes.

  20. Green synthesis of colloidal silver nanoparticles using natural rubber latex extracted from Hevea brasiliensis.

    Science.gov (United States)

    Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D; Baffa, Oswaldo

    2011-11-01

    Colloidal silver nanoparticles were synthesized by an easy green method using thermal treatment of aqueous solutions of silver nitrate and natural rubber latex (NRL) extracted from Hevea brasiliensis. The UV-Vis spectra detected the characteristic surface plasmonic absorption band around 435 nm. Both NRL and AgNO(3) contents in the reaction medium have influence in the Ag nanoparticles formation. Lower AgNO(3) concentration led to decreased particle size. The silver nanoparticles presented diameters ranging from 2 nm to 100 nm and had spherical shape. The selected area electron diffraction (SAED) patterns indicated that the silver nanoparticles have face centered cubic (fcc) crystalline structure. FTIR spectra suggest that reduction of the silver ions are facilitated by their interaction with the amine groups from ammonia, which is used for conservation of the NRL, whereas the stability of the particles results from cis-isoprene binding onto the surface of nanoparticles. Therefore natural rubber latex extracted from H. brasiliensis can be employed in the preparation of stable aqueous dispersions of silver nanoparticles acting as a dispersing and/or capping agent. Moreover, this work provides a new method for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

  1. A discrete particle swarm optimization algorithm with local search for a production-based two-echelon single-vendor multiple-buyer supply chain

    Science.gov (United States)

    Seifbarghy, Mehdi; Kalani, Masoud Mirzaei; Hemmati, Mojtaba

    2016-11-01

    This paper formulates a two-echelon single-producer multi-buyer supply chain model, while a single product is produced and transported to the buyers by the producer. The producer and the buyers apply vendor-managed inventory mode of operation. It is assumed that the producer applies economic production quantity policy, which implies a constant production rate at the producer. The operational parameters of each buyer are sales quantity, sales price and production rate. Channel profit of the supply chain and contract price between the producer and each buyer is determined based on the values of the operational parameters. Since the model belongs to nonlinear integer programs, we use a discrete particle swarm optimization algorithm (DPSO) to solve the addressed problem; however, the performance of the DPSO is compared utilizing two well-known heuristics, namely genetic algorithm and simulated annealing. A number of examples are provided to verify the model and assess the performance of the proposed heuristics. Experimental results indicate that DPSO outperforms the rival heuristics, with respect to some comparison metrics.

  2. Poly(2-acetoxyethyl methacrylate)/polystyrene latex interpenetrating polymer networks with well-defined phase-separated structure

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Shan Shi; Li Na Bian; Li Min Zhou; Li Qun Zhao; Shin Ichi Kuroda

    2011-01-01

    A series of poly (2-acetoxyethyl methacrylate)/polystyrene (PAEMA/PS) latex interpenetrating polymer networks (LIPNs) were prepared by seeded soap-free emulsion polymerization of styrene on the crosslinked PAEMA seed particles using an oil-soluble initiator. These PAEMA/PS LIPNs showed a well-defined phase-separated structure with PS phase dispersing in continuous PAEMA phase. The domain size of PS phase was found to depend on the crosslinking degree of PAEMA seed particles and the amount of second-stage styrene monomer.

  3. Investigating the rheological properties of native plant latex.

    Science.gov (United States)

    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).

  4. The antigenotoxic activity of latex from Himatanthus articulatus

    Directory of Open Access Journals (Sweden)

    Sebastião de O. Rebouças

    2012-04-01

    Full Text Available Himatanthus articulatus (Vahl Woodson (Apocynaceae is a native plant to the Amazon popularly used to treat ulcers, tumors, inflammations, cancer, syphilis and malaria. The aim of the present study was to investigate the in vivo genotoxic/antigenotoxic and mutagenic potential of this plant, using the comet and the micronucleus assays in mice. Female and male adult mice were treated with different doses of H. articulatus latex by gavage for two consecutive days. For the experiments, the latex was serially diluted with water to 1:2 (D1; 1:4 (D½ and 1:8 (D¼ and administered to the animals. The blood slides were exposed to hydrogen peroxide (ex vivo to evaluate antigenotoxic effect. Under the experimental conditions used in this study, the latex of H. articulatus did not increase the frequency of DNA damage as measured by the comet assay and micronucleus test in treated mice, indicating a non-genotoxic and non-mutagenic activity. In relation to the antigenotoxicity, latex exerted protective effect against DNA damage induced by hydrogen peroxide. Therefore, our results add new information about the antigenotoxic potential of H. articulatus latex, which is popularly used in the Amazon to treat different pathologies.

  5. Funastrain c II: a cysteine endopeptidase purified from the latex of Funastrum clausum.

    Science.gov (United States)

    Morcelle, Susana R; Trejo, Sebastián A; Canals, Francesc; Avilés, Francesc X; Priolo, Nora S

    2004-04-01

    A cysteine endopeptidase, named funastrain c II, was isolated and characterized from the latex of Funastrum clausum (Asclepiadaceae). The molecular mass (mass spectrometry) of the protease was 23.636 kDa. The analysis of funastrain c II by SDS-PAGE revealed a single polypeptide chain. The enzyme showed a remarkable stability of its caseinolytic activity after incubation at temperatures as high as 70 degrees C. Inhibition and activation assays indicated the cysteinic nature of the funastrain c II catalytic site. The optimum pH of funastrain c II enzymatic activity varied according to the substrate used (9.0-10.0 for casein and 6.2-6.8 for PFLNA). Kinetic parameters were determined for N-alpha-CBZ-Ala p-nitrophenyl ester (Km = 0.0243 mM, kcat = 1.5 s(-1)) and L-pyroglutamyl-L-phenylalanyl-L-leucine-p-nitroanilide (PFLNA; KM = 0.1011 mM, kcat = 0.9 s(-1)). The N-terminal sequence of funastrain c II showed considerable similarity to other proteases isolated from latex of different Asclepiadaceae species as well as to other cysteine proteinases belonging to the papain family.

  6. Occurrence and gas/particle partitioning of short- and medium-chain chlorinated paraffins in the atmosphere of Fildes Peninsula of Antarctica

    Science.gov (United States)

    Ma, Xindong; Zhang, Haijun; Zhou, Hongqiang; Na, Guangshui; Wang, Zhen; Chen, Chen; Chen, Jingwen; Chen, Jiping

    2014-06-01

    Chlorinated paraffins (CPs) were measured in air samples at a remote air monitoring site established in Georgia King Island, Fildes Peninsula of Antarctica (Great Wall Station, China) to study the long-range atmospheric transport of these anthropogenic pollutants to the Antarctic. Gas- and particle-phase CPs were collected using polyurethane foam plugs (PUF) and glass fiber filters (GFF) respectively during summertime of 2012. The total atmospheric levels of SCCPs and MCCPs ranged from 9.6 to 20.8 pg m-3 (average: 14.9 pg m-3) and 3.7-5.2 pg m-3 (average: 4.5 pg m-3), respectively. C10 and C11 carbon chain homologues with Cl5 and Cl6 chlorine atoms predominated in SCCP formula groups both in gas- and particle-phase. Significant linear correlation was found between gas/particle partition coefficients (KP) and sub-cooled liquid vapor pressures (pL°) (R2 = 0.437, p < 0.01), as well as KP and octanol-air partition coefficients (KOA) (R2 = 0.442, p < 0.01). Absolute slope values of two regression models (0.31 and 0.39) were less than 0.6 indicating that the way of absorption into organic matter of aerosol played a more important role on atmospheric partitioning and transferring of CPs in remote Antarctic area. Both the Junge-Pankow model and the KOA-based model tended to underestimate the sorption of lower chlorinated CPs and overestimate the sorption of highly chlorinated CPs.

  7. Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe.

    Science.gov (United States)

    Raja, Tanzeela Nazir; Brouwer, Albert M; Biemans, Koen; Nabuurs, Tijs; Tennebroek, Ronald

    2010-07-30

    In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe was copolymerized via emulsion polymerization. The presence of organic co-solvents inside the polymer particles is revealed by the photophysical properties of the probe. In particular, the position of the fluorescence emission maximum of co-polymerized can be used to measure the amount of coalescing agent present in the polymer particles. The spectral shifts are shown to be due to the softening of the matrix, rather than to solvation of the probe by the added co-solvent.

  8. DEFORMATION OF SOFT COLLOIDAL CRYSTALLINE STRUCTURE-THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCES BY SYNCHROTRON SMALL-ANGLE X-RAY SCATTERING ON TENSILE STRETCHED POLYMERIC LATEX FILM

    Institute of Scientific and Technical Information of China (English)

    Jian-qi Zhang; Yong-feng Men

    2009-01-01

    Films obtained via drying a polymeric latex dispersion are normally colloidal crystalline where latex particles are packed into a face centered cubic (fcc) structure.Different from conventional atomic crystallites or hard sphere colloidal crystallites,the crystalline structure of these films is normally deformable due to the low glass transition temperature of the latex particles.Upon tensile deformation,depending on the drawing direction with respect to the normal of specific crystallographic plane,one observes different crystalline structural changes.Three typical situations where crystallographic c-axis,body diagonal or face diagonal of the fcc structure of the colloidal crystallites being parallel to the stretching direction were investigated.Tilting angle and d-spacing of several crystallographic planes as a function of draw ratio at each situation were derived.Experimental evidences for such relationships were also given by considering in-situ synchrotron small angle X-ray scattering data of a typical latex film during stretching.It turns out that the experimental results are fully in accordance with the mathematical calculations.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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%.

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

    Science.gov (United States)

    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.

  12. GCMS analysis and antimicrobial action of latex of Euphorbia caducifolia

    Directory of Open Access Journals (Sweden)

    Manoj Goyal

    2012-04-01

    Full Text Available Euphorbia caducifolia is conspicuously and regularly represented in the flora of the Rajasthan state. Latex of E. caducifolia is used to cure skin infections, cutaneous eruption, leucoderma and applied to cuts and wounds for speedy healing. The GCMS analysis of fraction isolated from latex showed presence of methyl palmitate, 5,9-heptadecadienoate, methyl 11 octadecenoate, methyl octadecenoate and 3,7,11,15-tetramethyl- 2-hexadecene-l-ol. Isolated fraction of E. caducifolia (IFEC and latex of E. caducifolia (ECL were tested against S. aureus, M. luteus, B. subtilis, E. coli, S. typhi, A. niger and C. albicans. IFEC was found to be more effective against fungal species, and MIC was found to be 150 and micro;g/ml against A. niger. [J Intercult Ethnopharmacol 2012; 1(2.000: 119-123

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

    NARCIS (Netherlands)

    Wahler, D.; Colby, T.; Kowalski, N.A.; Harzen, A.; Wotzka, S.Y.; Hillebrand, A.; Fischer, R.; Helsper, J.P.F.G.; Schmidt, J.; Schulze Gronover, C.; Prüfer, D.

    2012-01-01

    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

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

    Science.gov (United States)

    2010-07-01

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

  15. 40 CFR 428.110 - Applicability; description of the latex foam subcategory.

    Science.gov (United States)

    2010-07-01

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

  16. IMMEDIATE AND DELAYED HYPERSENSITIVITY REACTIONS TO LATEX GLOVES IN A DENTAL STUDENT. A case report.

    Directory of Open Access Journals (Sweden)

    Iliyana Stoeva

    2011-08-01

    Full Text Available The article presents a case of dental student with immediate and delayed hypersensitivity reaction to latex gloves. Symptoms appeared during the second year of regularly using of latex gloves. The student was with no history of allergies and no previous exposure to latex products.

  17. Rheological behaviour of latexes in-can and during film drying

    NARCIS (Netherlands)

    Molenaar, F.; Svanholm, T.; Toussaint, A.

    1997-01-01

    In-can rheology was studied for sixteen model acrylate latexes and a commercial vinyl/acrylate copolymer latex. Following the model of Quemada, the shear thinning behaviour, the effects of latex neutralisation and the copolymer composition could be described. Furthermore, the rheological effects of

  18. Molecular detection of Papaya meleira virus in the latex of Carica papaya by RT-PCR

    NARCIS (Netherlands)

    Araujo, de M.M.M.; Tavares, E.T.; Silva, da F.R.; Marinho, V.L.D.; Souza, M.T.

    2007-01-01

    A RT-PCR assay was developed for early and accurate detection of Papaya meleira virus (PMeV) in the latex from infected papayas. The meleira disease is characterized by an excessive exudation of more fluidic latex from fruits, leaves and stems. This latex oxidises and gives the fruit a ¿sticky¿ text

  19. Rubber elongation factor (REF), a major allergen component in Hevea brasiliensis latex has amyloid properties.

    Science.gov (United States)

    Berthelot, Karine; Lecomte, Sophie; Estevez, Yannick; Coulary-Salin, Bénédicte; Bentaleb, Ahmed; Cullin, Christophe; Deffieux, Alain; Peruch, Frédéric

    2012-01-01

    REF (Hevb1) and SRPP (Hevb3) are two major components of Hevea brasiliensis latex, well known for their allergenic properties. They are obviously taking part in the biosynthesis of natural rubber, but their exact function is still unclear. They could be involved in defense/stress mechanisms after tapping or directly acting on the isoprenoid biosynthetic pathway. The structure of these two proteins is still not described. In this work, it was discovered that REF has amyloid properties, contrary to SRPP. We investigated their structure by CD, TEM, ATR-FTIR and WAXS and neatly showed the presence of β-sheet organized aggregates for REF, whereas SRPP mainly fold as a helical protein. Both proteins are highly hydrophobic but differ in their interaction with lipid monolayers used to mimic the monomembrane surrounding the rubber particles. Ellipsometry experiments showed that REF seems to penetrate deeply into the monolayer and SRPP only binds to the lipid surface. These results could therefore clarify the role of these two paralogous proteins in latex production, either in the coagulation of natural rubber or in stress-related responses. To our knowledge, this is the first report of an amyloid formed from a plant protein. This suggests also the presence of functional amyloid in the plant kingdom.

  20. Rubber elongation factor (REF, a major allergen component in Hevea brasiliensis latex has amyloid properties.

    Directory of Open Access Journals (Sweden)

    Karine Berthelot

    Full Text Available REF (Hevb1 and SRPP (Hevb3 are two major components of Hevea brasiliensis latex, well known for their allergenic properties. They are obviously taking part in the biosynthesis of natural rubber, but their exact function is still unclear. They could be involved in defense/stress mechanisms after tapping or directly acting on the isoprenoid biosynthetic pathway. The structure of these two proteins is still not described. In this work, it was discovered that REF has amyloid properties, contrary to SRPP. We investigated their structure by CD, TEM, ATR-FTIR and WAXS and neatly showed the presence of β-sheet organized aggregates for REF, whereas SRPP mainly fold as a helical protein. Both proteins are highly hydrophobic but differ in their interaction with lipid monolayers used to mimic the monomembrane surrounding the rubber particles. Ellipsometry experiments showed that REF seems to penetrate deeply into the monolayer and SRPP only binds to the lipid surface. These results could therefore clarify the role of these two paralogous proteins in latex production, either in the coagulation of natural rubber or in stress-related responses. To our knowledge, this is the first report of an amyloid formed from a plant protein. This suggests also the presence of functional amyloid in the plant kingdom.

  1. Trypsin inactivation by latex fabricated gold nanoparticles: A new strategy towards insect control.

    Science.gov (United States)

    Patil, Chandrashekhar D; Borase, Hemant P; Suryawanshi, Rahul K; Patil, Satish V

    2016-10-01

    Before applying nanotechnologies in biomedical and environmental areas it is advised to study interactions of nanoparticles and other nanomaterials with biomacromolecule present in living system. Moreover there is scarcity of reports on interactions between nanoparticles and biomaterials. In present report a rapid, ecofriendly method of fabricating stable gold nanoparticles (AuNPs) using latex of Jatropha curcas is reported for the first time. AuNPs found to have characteristic absorption maxima centered at 540nm, multiple irregular shapes with size range from 20 to 50nm and have crystalline nature. Latex fabricated AuNPs were found to inhibit catalytic potential of trypsin (a vital enzyme responsible for digestion, insecticide resistance and in several disease conditions). The interactions between AuNPs and trypsin were analyzed by UV-vis spectrophotometry and microwave plasma-atomic emission spectrometry which suggests formation of trypsin-AuNPs complex responsible for lowering catalytic activity of trypsin. Transmission electron microscopy, Fourier transform infrared spectroscopy and particle size distribution studies further confirm complex formation between trypsin and AuNPs. Diverse interactions of metal nanoparticles with proteins such as covalent interaction, electrostatic interactions and binding to SH group of amino acid may be the reasons behind inhibition of trypsin activity. In vivo studies on serum of several vectors and agriculturally important pests supported instrumental results on AuNPs induced trypsin inhibition. This work will bring a new research direction to explore eco-friendly nanoparticle in insect control via inhibition of enzyme catalytic potential.

  2. Identification and Analysis of Latex Proteins Related with the Tapping Panel Dryness (TPD) in Hevea brasiliensis

    Institute of Scientific and Technical Information of China (English)

    Kun Yuan; Zhenhui Wang; Lifu Yang

    2012-01-01

    The Tapping Panel Dryness (TPD) in Hevea brasiliensis is a complex physiological syndrome and seriously limits the increase of natural rubber production.In order to separate and identify the proteins closely correlated with TPD in Hevea brasiliensis,the proteins of latex C-serum,lutoid,rubber particle and total latex from healthy and TPD trees were separated by 2-DE respectively.Software analysis showed that 157 protein spots were differentially expressed in TPD trees compared with healthy ones.Subjected to MALDI-TOF-MS and searching for NCBInr or rubber database,49 protein spots of them were successfully identified,including 39 spots down-regulated and 10 up-regulated in TPD trees.The proteins mainly involved in rubber biosynthesis,stress response and reactive oxygen species (ROS) metabolism process and they might play key roles in TPD occuring.The current study will provide theoretical bases for further elucidating the mechanism underlying TPD in Hevea brasiliensis at the molecular level.

  3. Preparation and characterization of aqueous polyurethane oil/polyacrylate latex interpenetrating polymer network

    Science.gov (United States)

    Zhou, M. M.; Ma, L. L.; Du, J.; Cao, F.; Xiao, J. J.

    2015-07-01

    A series of aqueous polyurethane oil (network I)/polyacrylate (network II) latex interpenetrating polymer networks (LIPNs) were synthesized via the technology of latex interpenetrating polymer network combined seed emulsion polymerization process. Fourier transform infrared (FTIR) spectroscopy, laser particle size distributing analyzer and universal tension machine were utilized to characterize the bulk structures and mechanical properties of LIPNs. For used as damping material, the damping performance of LIPNs were analyzed by dynamic mechanical analysis (DMA). It was found that the damping temperature region of LIPN was wider than those of aqueous polyurethane oil, the temperature region with greater tanδ changed with the TPGDA content and hard-/soft-segment mass weight ratio (mMMA/mBA) and the glass transition temperature (Tg) of the network I and network II in LIPN occurred within shift each other, even overlap with increasing mMMA/mBA value. The results show that LIPNs synthesized through the combined process have greater tanδ and wider damping temperature region, which is suitable for the use of damping coatings.

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

    Science.gov (United States)

    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.

  5. Coadsorption of IgG and BSA onto sulfonated polystyrene latex: I. Sequential and competitive coadsorption isotherms.

    Science.gov (United States)

    Peula, J M; Hidalgo-Alvarez, R; de las Nieves, F J

    1995-01-01

    In this work the sequential and competitive coadsorption of IgG and BSA proteins on a sulfonate polystyrene latex with high surface charge density have been studied. For sequential coadsorption the IgG/a-CRP was first adsorbed and then the free surface of the particle was saturated by redispersion of the pellet in a solution with a high concentration of monomeric BSA (m-BSA). The competitive coadsorption experiments were carried out in two separate experiments by changing the initial concentration of one protein when the concentration of other protein was high and constant. During the incubation the pH was 5 or 6, and the ionic strength 2 mM, as in previous studies the adsorption of BSA was very low at neutral or basic pH regardless of the amount of adsorbed IgG. From these coadsorption experiments it was possible to obtain latex-protein complexes with a similar degree of coverage by each protein, high adsorption of IgG and different amounts of BSA, or high adsorption of BSA and a low, but significant, amount of IgG. The latex-protein complexes were electrokinetically characterized by measuring the electrophoretic mobility of each complex vs the pH of redispersion. In that way we can detect the i.e.p. of the complexes and the pH range in which the electrostatic repulsion can make them colloidally stable.

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

    Science.gov (United States)

    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.

  7. 纳米SiOx补强天然乳胶膜抗剪切机理的研究%Study on Shear Strength of Nature Rubber Latex Film reinforced with n-SiOx

    Institute of Scientific and Technical Information of China (English)

    刘东辉; 杨波; 黄俊; 徐亚丽

    2012-01-01

    Using the surface treatment agent, the high density dispersed suspension of n-SiOx was prepared though shear action, agitation-blend and ultrasonic wave. By suitable shear force, the suspension that the mass percentage of n-SiOx was 2.0% was evenly dispersed into nature rubber latex, and the nature rubber film sample reinforced with n-SiOx was prepared. The test results of angle tear strength and the SEM analysis showed that the n-SiOx particles could homogeneously disperse into the nature rubber latex, and form firm structure with the nature rubber latex s molecular chains, and the angle tear strength was 152. 32% of the film sample filled with silica. The main effecting factor was the density of the n-SiOx suspension, the secondary factors were the dispersing time of ultrasonic wave,the running frequency of 25G head and the emulsification time.%使用合适表面处理剂,通过剪切、搅拌混合和超声波处理,制备了高浓度n-SiOx分散悬浮液;在合适的剪切强度下,将分散悬乳液按n- SiOx质量分数为2.0%均匀分散在天然乳胶中,制备了n- SiOx补强型天然乳胶膜试样.乳胶膜直角撕裂强度测试结果和扫描电子显微镜图像分析表明,n- SiOx粒子较好地分散在天然乳胶中,能与乳胶分子链形成较为牢固的整体结构,其剪切强度较白炭黑试样提高了52.32%;n - SiOx悬浮液浓度是实验的主要影响因素,超声波分散时间、25G工作头转速和均质分散时间次之.

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

    Science.gov (United States)

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

    2014-01-01

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

  9. STRAIN HARDENING PROPERTIES OF STEEL FIBRE REINFORCED LATEX CONCRETE COMPOSITE

    Directory of Open Access Journals (Sweden)

    V.M. Sounthararajan

    2013-04-01

    Full Text Available Steel fibre addition in concrete possesses high merits in terms of achieving homogeneity and tensile strength properties. Polymeric addition in concrete has high advantages in terms of pore fillingeffect and subsequent increase in durability index. The combined addition of steel and polymeric latex additions in concrete leads to increased strength, durability, toughness, resistance to cracking and crack propagation. Studies were conducted in the present study to analyse the properties of concrete that can be further improved with the addition of polymer styrene butadiene rubber emulsion (SBR along with steel fibres. In this research analysis, styrene-butadiene rubber (SBR latex as a polymeric admixture was used in steel fibre reinforced concrete. The effect of curing conditions on the strength gain properties of composite steel fibre latex matrix on the compressive, flexural strength, and split tensile test of polymermodified steel fibre reinforced concrete (PSFC concrete was examined. Including SBR latex at a certain % of binder in the PSFC concrete improves the bonds within the cement matrix and steel fibres (SF. This is due to the SBR films formed in the matrix. By the comparison of properties of SFC and PSFC, it can be shown that a tremendous increase in compressive strength when 4% and 8% SBR is added along with 0.75% and 1.5% SF. The increase in flexural strength was noticed and post cracking ductility is imparted to concrete.

  10. SUBSTRATE EFFECTS ON VOC EMISSIONS FROM A LATEX PAINT

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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 ...

  12. Tensile Strength of PHBV/Natural Rubber Latex Mixtures

    Directory of Open Access Journals (Sweden)

    Promkotra Sarunya

    2015-01-01

    Full Text Available A polyhydroxybutyrate-co-hydroxyvalerate (PHBV is mingled with natural rubber latex (R to develop its mechanical property of the blend. Normally, substantial effects of the PHBV are hard, fragile, and inelastic, whereas the natural rubber is represented itself as very high elastic matter. The mixtures between the PHBV and natural rubber latex (R are considered in different proportions. The PHBV solutions (w/v are defined suitability at 1% (P1, 2% (P2, and 3% (P3. Their liquid mixtures of the PHBV to natural rubber latex (P:R are fabricated the blended films in three different ratios of 2:3, 1:1 and 3:2, respectively. The PHBV blended films are characterized the crystallinity form by x-ray diffractometry (XRD, which are appeared their identity crystals at 13.30 and 16.68 degree (2θ. Mechanical characterizations of the blends are examined by a universal testing machine (UTM. The average elastic moduli of P1, P2, and P3 mixtures are indicated as 773, 955, and 1,007 kPa, respectively. Their tensile strengths, similarly to elastic moduli, enhance with the PHBV concentrations. The effects of mechanical behaviors and crystallinity reveal that the PHBV blends can be improved their properties by more flexible with natural rubber latex.

  13. Acetylcholinesterase Inhibitory and Antioxidant Properties of Euphorbiacharacias Latex

    Directory of Open Access Journals (Sweden)

    Francesca Pintus

    2013-03-01

    Full Text Available The aim of the present study was to evaluate the acetylcholinesterase inhibitory capacity and the antioxidant properties of extracts of Euphorbia characias latex, a Mediterranean shrub. We performed a new extraction method involving the use of the trichloroacetic acid. The extract showed high antioxidant activity, was rich in total polyphenolic and flavonoid content and exhibited substantial inhibition of acetylcholinesterase activity.

  14. Oil-acrylic hybrid latexes as binders for waterborne coatings

    NARCIS (Netherlands)

    Hamersveld, van E.M.S.; Es, van J.; German, A.L.; Cuperus, F.P.; Weissenborn, P.; Hellgren, A.C.

    1999-01-01

    The combination of the characteristics of oil, or alkyd, emulsions and acrylic latexes in a waterborne binder has been the object of various studies in the past. Strategies for combining the positive properties of alkyds, e.g. autoxidative curing, gloss and penetration in wood, with the fast drying

  15. Alergia látex-fruta Latex-fruit allergy

    Directory of Open Access Journals (Sweden)

    Flávia Andréia MARIN

    2002-01-01

    Full Text Available O látex está sendo considerado o alergênico do ano 2000, tendo em vista que inúmeros indivíduos, principalmente profissionais da área de saúde e pacientes submetidos a várias intervenções diagnósticas e terapêuticas, estão freqüentemente expostos aos alérgenos do látex, presentes em produtos de borracha natural. As manifestações clínicas conseqüentes às reações alérgicas de hipersensibilidade imediata vão desde rinite, urticária, conjuntivite, angioedema, asma, até anafilaxia. Estudos recentes estão demonstrando que pacientes alérgicos ao látex desenvolvem concomitantemente sensibilização a certos alimentos de origem vegetal, especialmente frutas como papaia, figo, banana, abacate, kiwi, pêssego, abacaxi, melão e castanha, acreditando-se numa provável ocorrência de reações cruzadas entre os alérgenos do látex e destas frutas. Faz-se, então, uma revisão sobre a alergia ao látex, em particular sobre os grupos de risco, incluindo a presença de reatividade cruzada entre o látex e as frutas.The latex is being considered the allergenic agent of the year 2000, taking into account that several individuals, mainly health care professionals, and patients who had undergone many diagnostic and therapeutic interventions, are frequently exposed to latex allergens, which are present in natural rubber latex products. The clinical manifestations, derived from allergic reactions of immediate hypersensitivity vary from since rhinitis, conjunctivitis, urticaria, angioedema, asthma, to anaphylaxis. Recent researches are demonstrating that patients allergic to latex develop concomitantly sensitization to certain vegetable foods, especially fruits like papaya, fig, banana, avocado, kiwi, peach, pineapple, melon and chestnut, and a probable occurrence of cross reaction between allergens of latex and of these fruits is believed. A review is made about latex allergy, in particular about risk groups, including the presence of

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

    Science.gov (United States)

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

    2010-12-01

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

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

    Science.gov (United States)

    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

  18. Macrophage reprogramming: influence of latex beads with various functional groups on macrophage phenotype and phagocytic uptake in vitro.

    Science.gov (United States)

    Akilbekova, Dana; Philiph, Rachel; Graham, Austin; Bratlie, Kaitlin M

    2015-01-01

    Macrophages play a crucial role in initiating immune responses with various functions ranging from wound healing to antimicrobial actions. The type of biomaterial is suggested to influence macrophage phenotype. Here, we show that exposing M1- and M2-activated macrophages to polystyrene latex beads bearing different functional groups can alter secretion profiles, providing a possible method for altering the course of the host response. Macrophages were stimulated with either lipopolysaccharide or interleukin (IL) 4 and cultured for 24 h with 10 different latex beads. Proinflammatory cytokines (tumor necrosis factor α, monocyte chemotactic protein 1) and nitrite served as markers for the M1 phenotype and proangiogenic cytokine (IL-10) and arginase activity for M2 cells. The ability of the macrophages to phagocytize Escherichia coli particles and water contact angles of the polymers were also assessed. Different patterns of cytokine expression and phagocytosis activity were induced by the various particles. Particles did not polarize the cells toward one specific phenotype versus another, but rather induced changes in both pro- and anti-inflammatory markers. Our results suggest a dependence of pro- and anti-inflammatory cytokines and phagocytic activities on material type and cytokine stimuli. These data also illustrate how biomaterials can be exploited to alter host responses for drug delivery and tissue engineering applications.

  19. Performance Analysis of Styrene Butadiene Rubber-Latex on Cement Concrete Mixes.

    Directory of Open Access Journals (Sweden)

    Er. Kapil Soni

    2014-03-01

    Full Text Available To improve the performance of concrete, polymers are mixed with concrete. It has been observed that polymer-modified concrete (PMC is more durable than conventional concrete due to superior strength and high durability. In this research, effect of Styrene-Butadiene Rubber (SBR latex on compressive strength and flexural strength of concrete has been studied and also the optimum polymer (SBR-Latex content for concrete is calculated. This research was carried out to establish the effects of polymer addition on compressive and flexural strength using concrete with mix design of constant water-cement ratio at local ambient temperature. The mixes were prepared with Styrene-Butadiene Rubber (SBR latex -cement ratio of 0 %, 5%, 10%, 15% and 20%. Slump test was conducted on fresh concrete while compressive strength and flexural strength were determined at different age. A locally available Perma-Latex is used as SBR Latex. It has been observed that SBR latex has negative effect at early age while at 28 days, the addition of SBR latex in concrete results in enhancement of compressive strength and Flexural Strength. Based on the results of this study, latex modified concrete made using Perma-Latex may be recommended to be used with various types of concrete structures. However, for the mixes rich in cement, the dosage of SBR latex needs to be adjusted to maintain required workability of concrete.

  20. Synthesis of novel polymethacrylates with siloxyl bridging perfluoroalkyl side-chains for hydrophobic application on cotton fabrics

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Lu; Dai, Li; Yuan, Yanhua; Liu, Anqi [College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); National Engineering Laboratory for Modern Silk, Suzhou 215123 (China); Zhanxiong, Li, E-mail: lizhanxiong@suda.edu.cn [College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); National Engineering Laboratory for Modern Silk, Suzhou 215123 (China)

    2016-05-15

    Highlights: • Novel polymethacrylates with multi-perfluoroalkyl groups were reported. • TFSMA monomer in the polymer contributed much to the lower surface free energy. • PSD and TEM showed a broader size distribution with the increasing fluorine content. • EDS and XPS revealed migration of perfluoroalkyl chains under high temperature. - Abstract: Three novel fluorinated methacrylate monomers with siloxyl bridging perfluoroalkyl groups were synthesized and characterized. Afterwards, the corresponding polymethacrylate latexes, namely monofluoroalkylsiloxyl polymethacrylate (PMFSMA), bisfluoroalkylsiloxyl polymethacrylate (PBFSMA) and trisfluoroalkylsiloxyl polymethacrylate (PTFSMA), were prepared and coated onto cotton fabrics to make them water-repellent. Particle size, particle size distribution, zeta potential and high-resolution transmission electron microscope (TEM) were tested to assess the emulsion stability and particle morphology. Thermal properties of PTFSMA were evaluated by thermal-gravimetric analysis (TGA). Surface properties of the coated cotton fabrics were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), water contact angle (WCA), adhesive force and X-ray photoelectron spectroscopy (XPS). It was found that the incorporation of more perfluoroalkyl chains and the annealing process could decrease the surface free energy of polymer film to 13.7 mN/m. Furthermore, the EDS spectra of PTFSMA film after annealing showed an enrichment of fluorine in the film-air interface.

  1. Disseminated cryptococcal lymphadenitis with negative latex agglutination test

    Institute of Scientific and Technical Information of China (English)

    XU Xiao-guang; BI Xin-ling; WU Jian-hua; XU Hong; LIAO Wan-qing

    2012-01-01

    We reported an unusual case of disseminated cryptococcal lymphadenitis in an immunocompetent host who presented with fever and lymphadenopathy,which were the only two symptoms and signs.Latex agglutination test of serum and cerebrospinal fluid (CSF) were negative,while lymph node biopsy showed Cryptococcus neoformans.A diagnosis of disseminated cryptococcal lymphadenitis was made.Then the patient was treated with amphotericin B for 15 days as initial therapy and itraconazole for 6 months as maintenance therapy respectively.The patient received re-examination per 6 months and was followed up for 2 years.Swollen lymph nodes diminished gradually,and no fever or other symptoms were found.Latex agglutination test of serum and CSF were negative throughout the follow-up period,and anti-HIV,syphilis and tuberculosis antibody were all negative.

  2. A STUDY ON RADIATION CROSSLINKING OF POLYDIMETHYLSILOXANE (PDMS) RUBBER LATEX

    Institute of Scientific and Technical Information of China (English)

    Yi-cai Zhu; Xiao-hong Zhang; Jin-liang Qiao; Gen-shuan Wei

    2004-01-01

    Polydimethylsiloxane (PDMS) rubber latex with two sorts of sensitizers, trimethylol propane tri-methacrylate (TMPTMA) and diethylene glycol di-acrylate (DEGDA), was irradiated with γ-rays and electron beams in various conditions.The radiation crosslinking reaction of PDMS occurs in the inner phase of the latex and is relatively isolated from the water phase. Therefore the oxygen and the radicals produced by the radiolysis reaction of water almost have no effect on the crosslinking reaction of polymer. The experimental data correspond with the Charlesby-Pinner relationship in the main. The gelation doses, degree of crosslinking and degradation as well as G values of crosslinking were calculated. From them, the sensitization coefficients were derived to offer a quantitative measurement of the enhancing effect of sensitizer on the radiation crosslinking.

  3. Durability of styrene-butadiene latex modified concrete

    Energy Technology Data Exchange (ETDEWEB)

    Shaker, F.A.; El-Dieb, A.S.; Reda, M.M. [Ain Shams Univ., Cairo (Egypt). Dept. of Structural Engineering

    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.

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

    Science.gov (United States)

    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.

  5. Extractable protein of radiation vulcanized natural rubber latex

    Energy Technology Data Exchange (ETDEWEB)

    Soebianto, Y.S. [Center for Research and Development of Isotopes and Radiation Technology, BATAN, Jakarta (Indonesia); Upul, R.M. [Rubber Research Institute of Sri Lanka, Ratmalana (Sri Lanka); Makuuchi, K.; Yoshii, F.; Kume, T. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    A new method to reduce the protein level in the latex products by irradiation is reported. Water soluble protein (WSP) solution (10%) was added into radiation vulcanized NR latex (RVNRL) as much as 3 phr in three different processes: added to RVNRL, added to re-centrifuged RVNRL, and added to RVNRL followed by centrifugation. The protein content was determined by enhanced BCA method, and identified by SDS-PAGE analysis. Addition of WSP followed by centrifugation reduces EP up to the minimum protein detection, and shortens the leaching time to 20-30 min. SDS-PAGE analysis confirms the reduction of soluble protein in the serum phase, and disappearance of protein bands in the rubber extract. Protein-WSP interaction produces water soluble complex, and removed by centrifugation. The molecular weight of WSP dictates the efficiency of protein removal. (author)

  6. Purification and Characterization of a Proteolytic Enzyme from Fig Latex

    Institute of Scientific and Technical Information of China (English)

    HUANG Lu; QU He-zhi; ZHANG Lei; DU Shan-shan; YANG Shuo; HAO Dong-yun; WANG Xiao-ping

    2008-01-01

    Ficin is an important component of plants in Ficus family such as fig latex. It is of special significance in medicine and industry because it exhibits activity throughout a wide range of temperature and pH values. In this work,we purified a component of ficin from the latex homogeneity of Shandong fig trees, and the properties of the purified ficin were studied. The current findings revealed that heavy metal ions were able to inhibit ficin, while DTT, L-cysteine,and β-ME were found to promote ficin activity. It was also observed that the half life of ficin at 65℃ was longer than 1 h and the Michaelis constant(Km) for casein hydrolyzation was determined to be 1.56 mg/mL. Our study shows that this purified ficin is a cysteine protease.

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

    Science.gov (United States)

    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.

  8. Electrical Resistance and Microstructure of Latex Modified Carbon Fiber Reinforced Cement Composites

    Institute of Scientific and Technical Information of China (English)

    WEI Jian; CHENG Feng; YUAN Hudie

    2012-01-01

    The electrical resistance,flexural strength,and microstructure of carbon fiber reinforced cement composites (CFRC) were improved greatly by adding water-redispersible latex powder.The electrical resistance of CFRC was investigated by two-probe method.The input range of CFRC based strain sensors was therefore increased,whereas electrical resistance was increased and remained in the perfect range of CFRC sensors.The analysis of scanning electron microscopy indicated that elastic latex bridges and a latex layer existed among the interspaces of the adjacent cement hydration products which were responsible for the enhancement of the flexural strength and electrical resistance.The formation mechanism of the elastic latex bridges was also discussed in detail.The continuous moving of two opposite interfaces of the latex solution-air along the interspaces of the adjacent hydrated crystals or colloids was attributed to the formation of the elastic latex bridges.

  9. Latex producing plants in Greece. [Euphorbiaceae acanthothamnos, E. dendroides

    Energy Technology Data Exchange (ETDEWEB)

    Margaris, N.S.; Vokou, D.

    1985-01-01

    The occurrence of energy rich plants, due to their content of stored hydrocarbons, provides the possibility of their exploitation as alternative and renewable energy sources. The contribution of a great number of latex producing plants in the native Greek flora favours experimental work in this direction. Data on the occurence of Euphorbiaceae in Greece and special growth characteristics of two species, namely E. acanthothamnos and E. dendroides, are provided. 13 references.

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

    Science.gov (United States)

    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.

  11. A new cytotoxic cardenolide from the latex of Antiaris toxicaria

    Institute of Scientific and Technical Information of China (English)

    Yu Juan Gan; Wen Li Mei; YOU Xing Zhao; Hao Fu Dai

    2009-01-01

    A new cardenolide,toxicarioside E(1),was isolated from the latex of Antiaris toxicaria(Pers.)Lesch(Moraceae).Its structure was elucidated on the basis of spectral data and chemical evidence.Compound 1 showed significant cytotoxicity against K562 and SGC-7901 cell lines in vitro by MTT method with the IC50 value of 0.026 and 0.027μg/mL,respectively.

  12. Progress in radiation vulcanization of natural rubber latex

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, Keizo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Vulcanization dose defined as the radiation dose at which cross-linked natural rubber in latex has the maximum tensile strength can be reduced by adding carbon tetrachloride as a reaction accelerator. The radiation vulcanization of natural rubber latex was selected as one of regional projects of IAEA in 1989 and a pilot plant was built in Jakarta. The products from it were evaluated during 1983-1985, followed by IAEA decision to support the continued R and D study at Takasaki, JAERI. Various factors to improve the properties of the products have been studied. Several advantages of the process over conventional method, such as absence of N-nitrosoamines, low cytotoxicity, decomposability in the environment, transparency and softness, were confirmed. The technology has been transferred toward commercial application in Thailand, and pilot plants being set up in Indonesia, India, Malaysia and Thailand. Moreover, the process was found to be effective in reducing protein remaining in natural rubber latex products and the initial investment and irradiation cost was found to be greatly reduced by employing low energy electron accelerator. This paper reviews such progress. (S. Ohno)

  13. Extractable proteins from field radiation vulcanized natural rubber latex

    Energy Technology Data Exchange (ETDEWEB)

    Parra, Duclerc F. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)]. E-mail: dfparra@ipen.br; Pinto Martins, Carlos Felipe [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Collantes, Hugo D.C. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Lugao, Ademar B. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)

    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 {sup 60}Co 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.

  14. CDNA library from the Latex of Hevea brasiliensis

    Directory of Open Access Journals (Sweden)

    Wilaiwan Chotigeat

    2010-12-01

    Full Text Available Latex from Hevea brasiliensis contains 30-50% (w/w of natural rubber (cis-1,4-polyisoprene, the important rawmaterial for many rubber industries. We have constructed a cDNA library from the latex of H. brasiliensis to investigate theexpressed genes and molecular events in the latex. We analyzed 412 expressed sequence tags (ESTs. More than 90% of theEST clones showed homology to previously described sequences in public databases. Functional classification of the ESTsshowed that the largest category were proteins of unknown function (30.1%, 11.4% of ESTs encoded for rubber synthesisrelatedproteins (RS and 8.5% for defense or stress related proteins (DS. Those with no significant homology to knownsequences (NSH accounted for 8.7%, primary metabolism (PM and gene expression and RNA metabolism were 7.8% and6.6%, respectively. Other categories included, protein synthesis-related proteins (6.6%, chromatin and DNA metabolism(CDM 3.9%, energy metabolism (EM 3.4%, cellular transport (CT 3.2%, cell structure (CS 3.2%, signal transduction (ST2.2%, secondary metabolism (SM 1.7%, protein fate (PF 2.2%, and reproductive proteins (RP 0.7%.

  15. Histamine mediates the pro-inflammatory effect of latex of Calotropis procera in rats

    Directory of Open Access Journals (Sweden)

    Yatin M. Shivkar

    2003-01-01

    Full Text Available Introduction: Calotropis procera is known to produce contact dermatitis and the latex of this plant produces intense inflammation when injected locally. However, the precise mode of its pro-inflammatory effect is not known. In present study we have pharmacologically characterized the inflammation induced by latex of C. procera in a rat paw edema model and determined the role of histamine in latex-induced inflammation.

  16. A hybrid particle swarm optimization and genetic algorithm for closed-loop supply chain network design in large-scale networks

    DEFF Research Database (Denmark)

    Soleimani, Hamed; Kannan, Govindan

    2015-01-01

    Today, tracking the growing interest in closed-loop supply chain shown by both practitioners and academia is easily possible. There are many factors, which transform closed-loop supply chain issues into a unique and vital subject in supply chain management, such as environmental legislation...... and effective solution methodology. On the other hand, this research considers improving closed-loop supply chain network optimization processes through dealing with mathematical programming tools; developing a deterministic multi-product, multi-echelon, multi-period model; and finally presenting an appropriate......, customer awareness, and the economical motivations of the organizations. However, designing and planning a closed-loop supply chain is an NP-hard problem, which makes it difficult to achieve acceptable results in a reasonable time. In this paper, we try to cope with this problem by proposing a new...

  17. STUDY ON THE PROPERTIES OF BLEND OF NATURAL RUBBER LATEX/METHYL METHACRYLATE GRAFTED RUBBER LATEX BY GAMMA RADIATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Natural rubber latex (NRL) and methyl methacrylate (MMA) grafted rubber latex were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature.The tensile properties,swelling ratio and permanent set were measured.The maximum tensile strength and modulus at 500% elongation were obtained at an absorbed dose of 8 kGy.Modulus increases from 6.99 Mpa to 9.87 Mpa for an increase in proportion of MMA grafted rubber from 40% to 60% in the blend at similar absorbed dose.Elongation at break and swelling ratio decrease with increasing absorbed dose as well as the MMA grafted rubber content in the blends.The decreasing trend of permanent set is high up to 5 kGy absorbed dose, and beyond that dose,it becomes almost flat.

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

    Science.gov (United States)

    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.

  19. Elements of the LaTeX system for the development of large publications

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    This document presents gives a quick overview over the LATEX system from the viewpoint of the production of books and complex papers. Thereby it provides the starting point for the author's selection of a set of LATEX packages and the development of related commands.......This document presents gives a quick overview over the LATEX system from the viewpoint of the production of books and complex papers. Thereby it provides the starting point for the author's selection of a set of LATEX packages and the development of related commands....

  20. Natural Rubber Latex Hypersensitivity with Skin Prick Test in Operating Room Personnel

    Directory of Open Access Journals (Sweden)

    Seyed Hessamedin Nabavizadeh

    2009-12-01

    Full Text Available 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.Results: 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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  3. [Detection of mutans streptococci by latex agglutination test and its application as a caries-activity test].

    Science.gov (United States)

    Takei, T

    1990-06-01

    The number of mutans streptococci in saliva and dental plaque has been reported to correlate with the incidence of dental caries. This report describes a simple and rapid diagnostic method for the detection of mutans streptococci in dental plaque using latex agglutination (LA) test. Latex particles (0.876 microns, diameter) were sensitized with partially purified antibodies against whole cells of Streptococcus mutans MT8148 (c), MT703R (e) and OMZ175 (f) and Streptococcus sobrinus B13 (d) and 6715 (g). Whole cells of mutans streptococci or dental plaque was extracted with a mixture of 8M sodium nitrite (5 microliters) and 2M acetic acid (5 microliters) for five minutes and neutralized with 2M sodium hydroxide (10 microliters), and the extract and the sensitized latex suspension (20 microliters) were mixed and the grade of agglutination reaction was read macroscopically after ten minutes standing at room temperature. The LA tests could detect 1.0 10ng of purified serotype antigen and 10(5)-10(6) CFU of live cells of mutans streptococci and specifically distinguish not only the mutans streptococci from the other streptococci but also S. mutans from S. sobrinus. However, cross-reactions were still observed among the serotypes c, e and f of S. mutans or between the serotypes d and g of S. sobrinus. Plaque samples were collected from 168 children (2 to 12 years of age) and the 0.1 mg (wet weight) were applied to the LA tests. At the same time, the total number of mutans streptococci in plaque and the serotypes of each isolate were determined. The results of LA reaction correlated significantly with the number of mutans streptococci in plaque (chi-square analysis; p less than 0.0001). The LA tests discriminated between S. mutans and S. sobrinus in dental plaque. It was found that the latex particles sensitized with anti-serotype c and/or e S. mutans antibodies were most effective in demonstrating mutans streptococci, and they were used in the following studies. The

  4. 无皂RAFT乳液聚合制备聚苯乙烯的阳离子型胶乳%Soap-Free Emulsion Polymerization of Styrene Using Macro-RAFT Agent to Make Cationic Latex

    Institute of Scientific and Technical Information of China (English)

    厉正赏; 罗英武

    2013-01-01

    A cationic amphiphilic macro-RAFT (reversible addition-fragmentation chain transfer) agent, P4VPm-b-PSn-CPDTTC (m=10, 15, 20, 30, n≈6), was synthesized as a surfactant in RAFT emulsion polymerization of styrene. The effects of neutralization degree and length of 4-vinylpyridine block of the agent on the soap-free emulsion polymerization were examined. The results show that a higher neutralization degree results in a longer inhibition period, and a longer 4-vinylpyridine block leads to a shorter inhibition period and a higher polymerization rate. The obtained latex particles have the average diameter of about 40 nm with a very wide range of particle size distribution. On the early stage of polymerization, the number-average molecular weight Mn of the obtained latex agreed well with what was predicted theoretically, but later on, it started to deviate; all of the polydispersity index (PDI) first rose, and then fell. At the end of polymerization, the PDIs were very high, and they increased with the increase of the neutralization degree.%设计合成了一系列可阳离子化两亲性大分子逆加成-断裂链转移(RAFT)试剂P4VPm-b-PSn-CPDTTC (m=10,15,20,30,n≈6),并考察了大分子RAFT试剂中和程度及4-乙烯基吡啶(4VP)段长度对苯乙烯的无皂RAFT乳液聚合的影响.结果发现,中和程度越高,阻聚期越长;4VP段越长,阻聚期越短,而聚合速率则越快;所得胶乳的粒径为40 nm左右,粒径分布很宽,反应前期数均分子量(Mn)的实验值与理论值吻合较好,中后期开始偏离;分子量分布指数(PDI)都是先升高后降低,反应结束后PDI很高,且随中和程度的增加而升高.

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

    Science.gov (United States)

    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

  6. Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry.

    Science.gov (United States)

    Xiao, Feng; Lam, Kit Ming; Li, Xiao-yan

    2013-05-01

    An advanced particle-tracking and flow-visualization technology, particle image velocimetry (PIV), was utilized to investigate the hydrodynamic properties of large aggregates in water. The laser-based PIV system was used together with a settling column to capture the streamlines around two types of aggregates: latex particle aggregates and activated sludge (AS) flocs. Both types of the aggregates were highly porous and fractal with fractal dimensions of 2.13±0.31 for the latex particle aggregates (1210-2144 μm) and 1.78±0.24 for the AS flocs (1265-3737 μm). The results show that PIV is a powerful flow visualization technique capable of determining flow field details at the micrometer scale around and through settling aggregates and flocs. The PIV streamlines provided direct experimental proof of internal flow through the aggregate interiors. According to the PIV images, fluid collection efficiency ranged from 0.052 to 0.174 for the latex particle aggregates and from 0.008 to 0.126 for AS flocs. AS flocs are apparently less permeable than the particle aggregates, probably due to the extracellular polymeric substances (EPSs) produced by bacteria clogging the pores within the flocs. The internal permeation of fractal aggregates and bio-flocs would enhance flocculation between particles and material transport into the aggregates.

  7. Vacuum coagulation of natural rubber latex and the properties of the produced natural raw rubber%真空凝固天然橡胶胶乳及其生胶性能

    Institute of Scientific and Technical Information of China (English)

    雷统席; 蒋盛军; 符乃方; 李鸿; 谢飞扬; 马洪泉

    2011-01-01

    在真空条件下,天然胶乳橡胶粒子会膨胀、破裂,从而引起天然胶乳的凝固.本研究首次将真空技术引入天然胶乳凝固领域.真空凝固天然胶乳可物理控速、凝固彻底、胶清清澈、污染低.与酸凝固天然胶乳的生胶及微生物凝固天然胶乳的生胶相比,真空凝固胶具备多孔、叠层结构,干燥失水快、抗氧指数(PRI)高、硫化速度较快,硫化后物理机械性能在3种硫化胶中最优.本研究为天然胶乳的凝固提供了一种新的物理方法.%Under vacuum natural rubber particles in natural rubber latex will expand, burst and coagulate. In this study, vacuum technology was applied to coagulate natural rubber latex. This vacuum coagulation of natural rubber latex could be controlled physically. The skim latex obtained as a byproduct during this procedure was cleaner than that obtained from other procedures; this procedure would therefore reduce pollution from latex processing. The natural raw rubber produced by vacuum coagulation had a porous and layered structure. Compared with the natural raw rubber coagulated by acid and microbiological methods, the natural raw rubber produced in this study was faster to dehydrate and vulcanize, and had a higher plasticity retention index. The vulcanized rubber from vacuum coagulation had better physical and mechanical properties than that prepared by acid or microbiological coagulation. The method developed in this work is a novel physical way to coagulate natural rubber latex.

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

    Science.gov (United States)

    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.

  9. Latex Allergy, a Special Risk for Patients with Chronic Illness and Health Care Workers

    Directory of Open Access Journals (Sweden)

    A.Zafer Caliskaner

    2008-06-01

    Full Text Available Natural rubber latex allergy is a new illness whose prevalence has reached epidemic proportions in highly exposed populations such as health care workers and who has chronic illness. After anaphylactic type reactions due to latex has been shown as case reports. The major risk factors in latex are intense exposure to latex allergens (surgical gloves, catheters, etc, atopy, hand eczema, female gender, history of multiple operations and dental interventions. An association between latex allergy and allergy to various fruits (banana, kiwi, avocado, pineapple, etc has been reported. Latex allergy is responsible for a wide spectrum of clinical symptoms ranging from a mild dermatitis to severe anaphylaxis. In this report, we present that latex related systemic allergic reactions cases; the first one is 24 years old nurse woman who is working at the blood bank in our hospital and the other one is 32 years old woman patient who has repeatative medical examination, and in vitro fertilisation therapy plan and suffered for systemic allergic reaction due to latex gloves which was used in her last concha operations. [TAF Prev Med Bull 2008; 7(3.000: 265-268

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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...

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

    Directory of Open Access Journals (Sweden)

    Monica Lamberti

    2015-10-01

    Full Text Available Objectives: 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. Material and Methods: 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. Results: 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%. Conclusions: 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.

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

    Science.gov (United States)

    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...

  16. Isotactic polypropylene/carbon nanotube composites prepared by latex technology: electrical conductivity study

    NARCIS (Netherlands)

    Grossiord, N.; Wouters, M.E.L.; Miltner, H.E.; Lu, K.; Loos, J.; Mele, B.V.; Koning, C.E.

    2010-01-01

    Several series of nanocomposites were prepared using a latex-based process, the main step of which consisted of mixing an aqueous suspension of exfoliated carbon nanotubes (CNTs) and a polymer latex. In the present work, a systematic study on the electrical properties of fully amorphous (polystyrene

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

    Science.gov (United States)

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

    2015-05-01

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

  18. Prevalence of latex-specific IgE antibodies in hospital personnel

    NARCIS (Netherlands)

    Kaczmarek, RG; Silverman, BG; Gross, TP; Hamilton, RG; Kessler, E; ArrowsmithLowe, JT; Moore, RM

    1996-01-01

    Background: Rubber latex hypersensitivity is an important concern for health care workers. Purpose: The Center for Devices and Radiological Health, in collaboration with the Consumer Product Safety Commission, conducted a multicenter study of the prevalence of latex-specific IgE antibodies among Uni

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

    Directory of Open Access Journals (Sweden)

    Meret Huber

    2016-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  1. Characteristics of Red Algae Bioplastics/Latex Blends under Tension

    Directory of Open Access Journals (Sweden)

    M. Nizar Machmud

    2013-10-01

    Full Text Available Cassava, corn, sago and the other food crops have been commonly used as raw materials to produce green plastics. However, plastics produced from such crops cannot be tailored to fit a particular requirement due to their poor water resistance and mechanical properties. Nowadays, researchers are hence looking to get alternative raw materials from the other sustainable resources to produce plastics. Their recent published studies have reported that marine red algae, that has been already widely used as a raw material for producing biofuels, is one of the potential algae crops that can be turned into plastics. In this work, Eucheuma Cottonii, that is one of the red alga crops, was used as raw material to produce plastics by using a filtration technique. Selected latex of Artocarpus altilis and Calostropis gigantea was separately then blended with bioplastics derived from the red algae, to replace use of glycerol as plasticizer. Role of the glycerol and the selected latex on physical and mechanical properties of the red algae bioplastics obtained under a tensile test performed at room temperature are discussed. Tensile strength of some starch-based plastics collected from some recent references is also presented in this paperDoi: 10.12777/ijse.5.2.81-88 [How to cite this article: Machmud, M.N., Fahmi, R.,  Abdullah, R., and Kokarkin, C.  (2013. Characteristics of Red Algae Bioplastics/Latex Blends under Tension. International Journal of Science and Engineering, 5(2,81-88. Doi: 10.12777/ijse.5.2.81-88

  2. Cytotoxic Orbitide from the Latex of Croton urucurana.

    Science.gov (United States)

    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.

  3. [Erythroderma secondary to latex-producing plants (Synadenium grantii)].

    Science.gov (United States)

    Docampo, Patricia C; Cabrerizo, Silvia; Paladino, Nadia; Parreño, María L; Ruffolo, Virginia; Mutti, Olga

    2010-12-01

    The Euphorbiaceae family are plants that have in common latex production. There are over 8000 species. They have worldwide distribution. We can find trees, shrubs or herbs. Many important species belong to this family and they are used in our country for industrial and medical purposes. There are also ornamental plants with attractive appearance that stimulate children curiosity, intake or manipulation. In the National Poison Center consultations for plants represent a small number (0.2%) of the total accidents in children, however they can be serious. We report the case of a 4 years old girl who manipulated and swallowed part of an Euphorbiaceae family plant (Synadenium grantii).

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

    Science.gov (United States)

    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.

  5. 磁场诱导和晶种联合法制备链状Fe3O4%Seed-Mediated Synthesis of Chain-like Fe3O4 Particle Under Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    杨喜云; 于培峰

    2012-01-01

    One-dimensional chain-like magnetite particles were prepared by a seed-mediated growth method un der the induction of magnetic field. The seeds, 700nm in size, were added into the mixture of FeSO4 ? 7H2O,FeCl3 ? 6H2O and urea. The effects of magnetic field intensity, seed amount, dispersant polyvinylpyrrolidone(PVP) concen tration and reaction time on the morphology of samples were discussed. The results showed that the number of chain like particles increased with an increase of both magnetic field and seed amount Appropriate PVP was favorable to ob tain parallel chains. The optimum conditions for preparation of chain-like particles are 0. 35T magnetic field, 10% seed, 7. 5g/L PVP and 18h reaction time. Magnetic measurements reveal that magnetite chains are ferromagnetic with a saturation magnetization of 72. 3emu/g and coercivity of 381Oe.%以粒径为700nm的球形Fe3O4为晶种,将晶种加入到含有FeSO4·7H2O、FeCl3·6H2O与尿素的混合溶液中,在磁场诱导下制备链状Fe3O4.研究了磁场强度、晶种添加量、分散剂聚乙烯吡咯烷酮(PVP)质量浓度以及反应时间对产品形貌的影响.研究结果表明,随着磁场强度的增大、晶种量的增加,链状粒子数目显著增多;适量的PVP能使链状粒子分散平行排列.合成链状Fe3O4粒子的最佳工艺条件为磁场强度0.35T,晶种用量10%,PVP质量浓度7.5g/L,反应18h.磁性能测试表明,该链状Fe3O4粒子具有亚铁磁性,磁饱和强度为72.3emu/g,矫顽力为381Oe.

  6. Subtractive cDNA cloning using oligo(dT)30-latex and PCR: isolation of cDNA clones specific to undifferentiated human embryonal carcinoma cells.

    OpenAIRE

    1991-01-01

    The human embryonal carcinoma cell line NEC14 can be induced to differentiate by the addition of 10(-2)M N,N'-hexamethylene-bis-acetamide (HMBA). A subtractive cDNA library specific to undifferentiated NEC14 cells was constructed using oligo(dT)30-Latex and polymerase chain reaction (PCR). The method was designed to improve the efficiency of subtraction and the enrichment of cDNA clones corresponding to low abundance mRNAs. The single strand of cDNA was made from mRNA prepared from the HMBA-t...

  7. A latex agglutination test for the field determination of abnormal vitellogenin production in male fishes contaminated by estrogen mimics

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes, Ilizabete [Laboratoire d' Immunologie-Microbiologie (LIM/ESE-CNRS, unite FRE2635), IUT de Thionville-Yutz, 1, Impasse A Kastler, F-57970 Yutz (France); Pihan, Jean-Claude [Laboratoire de Production des Ecosystemes et Ecotoxicologie (LBFE), UFR SciFa, campus Bridoux, rue du G Delestraint, F-57070 Metz (France); Falla, Jairo [Laboratoire d' Immunologie-Microbiologie (LIM/ESE-CNRS, unite FRE2635), IUT de Thionville-Yutz, 1, Impasse A Kastler, F-57970 Yutz (France)

    2004-06-09

    Estrogen mimics are pollutants present in the aquatic environment. These compounds induce abnormalities in the reproductive system of male fishes, which lead to a total or partial male feminization, or to their demasculinization. Ultimately, these alterations could lead to a disappearance of the total contaminated fish population. Moreover, these toxic substances possess the capacity to mimic endogenous estrogens and to induce the abnormal production of vitellogenin (VTG) in male and immature fishes. The purpose of this research was to develop an easy, specific, cheap and fast method for diagnosing the contamination of male fishes by estrogen mimics, using VTG as biomarker. The selected method is based on a reverse latex agglutination test (rLAT), developed with monoclonal antibodies specific of this biomarker. The development of this VTG-rLAT has involved, firstly, the purification of carp VTG to produce monoclonal antibodies, specifics of this protein. One of these antibodies was selected to recover latex particles (diameter: 1 {mu}m). Finally, the immunoreactivity of the VTG-rLAT was verified with different fish plasma samples from males treated with 17{beta}-estradiol and non-treated males or females in vitellogenesis.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Shishir Ram Shetty

    2011-02-01

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

  10. Ease of donning commercially available latex examination gloves.

    Science.gov (United States)

    Cóté, S J; Fisher, M D; Kheir, J N; Paull, R B; Neal, J G; Jackson, E M; Suber, F; Thacker, J G; O'Keefe, J S; Edlich, R F

    1998-01-01

    There are a wide variety of latex examination gloves now available for use by health care providers. A prospective randomized trial was completed to quantify the forces required to don a sample of seven cornstarch-lubricated gloves and 13 powder-free latex examination gloves. The data collected was analyzed by a 20 x 2 general factorial ANOVA, as well as two 1-way ANOVAs using a least significance difference post hoc test. Some powder-free gloves can be easily donned with dry or wet hands without tearing with forces comparable to those encountered with powdered gloves. With the advent of these powder-free examination gloves, powdered gloves can now be abandoned, protecting health professionals and patients from the dangers of absorbable dusting powders. Despite the dangers of the absorbable dusting powders and the Food and Drug Administration's requirement for labeling examination glove boxes, some manufacturers of powdered examination gloves do not appropriately label their boxes with a warning to the health professional and patient of the presence of powder.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Arif Siti AM

    2005-08-01

    Full Text Available Abstract 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

  13. Intracellular particle tracking as a tool for tumor cell characterization

    NARCIS (Netherlands)

    Li, Yixuan; Duits, Michel H.G.; Schnekenburger, Jürgen

    2009-01-01

    We studied the dynamics of two types of intracellular probe particles, ballistically injected latex spheres and endogenous granules, in tumor cell lines of differerent metastatic potential: breast tumor cells (MCF-7 malignant, MCF-10A benign) and pancreas adenocarcinoma (PaTu8988T malignant, PaTu898

  14. Radiation vulcanization of natural rubber latex (part 6). Improvement of aging propreties of latex lubber vulcanized with radiation

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, Keizo; Tsushima, Kyogo

    1988-10-15

    Concerning the vulcanization of natural rubber latex with radiation by using acrylic ester as accelerator, causes for loss of anti-aging property by leaching and counter-measure against it were reported. For the experiment, 2-ethyl hexyl acrylate with carbon tetra-chloride as accelerator, 2% aqueous solution of ammonia or acetic acid as leaching water, were used. For the analysis of extracts, ultra-violet absorption and gas chromatography were applied. As the result of the experiment, it was recognized that anti-aging property was more decreased by more increased quantity of extracted protein which was naturally contained in the natural rubber latex and functioned as anti-aging material, and that by radiation vulcanization, non-rubber components were destroyed to result the increased quantity of extracts compared with that of non-vulcanized. Concerning the improvement of anti-aging property, experimental comparison of miscellaneous methods resulted that the addition of sodium di-n-buthyl di-thiocarbamate was most effective. 3 references, 3 figures, 5 tables.

  15. Synthesis of novel polymethacrylates with siloxyl bridging perfluoroalkyl side-chains for hydrophobic application on cotton fabrics

    Science.gov (United States)

    Cai, Lu; Dai, Li; Yuan, Yanhua; Liu, Anqi; Zhanxiong, Li

    2016-05-01

    Three novel fluorinated methacrylate monomers with siloxyl bridging perfluoroalkyl groups were synthesized and characterized. Afterwards, the corresponding polymethacrylate latexes, namely monofluoroalkylsiloxyl polymethacrylate (PMFSMA), bisfluoroalkylsiloxyl polymethacrylate (PBFSMA) and trisfluoroalkylsiloxyl polymethacrylate (PTFSMA), were prepared and coated onto cotton fabrics to make them water-repellent. Particle size, particle size distribution, zeta potential and high-resolution transmission electron microscope (TEM) were tested to assess the emulsion stability and particle morphology. Thermal properties of PTFSMA were evaluated by thermal-gravimetric analysis (TGA). Surface properties of the coated cotton fabrics were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), water contact angle (WCA), adhesive force and X-ray photoelectron spectroscopy (XPS). It was found that the incorporation of more perfluoroalkyl chains and the annealing process could decrease the surface free energy of polymer film to 13.7 mN/m. Furthermore, the EDS spectra of PTFSMA film after annealing showed an enrichment of fluorine in the film-air interface.

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

    Science.gov (United States)

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

    2013-12-01

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

  17. In vitro antiviral activity of Ficus carica latex against caprine herpesvirus-1.

    Science.gov (United States)

    Camero, Michele; Marinaro, Mariarosaria; Lovero, Angela; Elia, Gabriella; Losurdo, Michele; Buonavoglia, Canio; Tempesta, Maria

    2014-01-01

    The latex of Ficus carica Linn. (Moraceae) has been shown to possess antiviral properties against some human viruses. To determine the ability of F. carica latex (F-latex) to interfere with the infection of caprine herpesvirus-1 (CpHV-1) in vitro, F-latex was resuspended in culture media containing 1% ethanol and was tested for potential antiviral effects against CpHV-1. Titration of CpHV-1 in the presence or in the absence of F-latex was performed on monolayers of Madin Darby Bovine Kidney (MDBK) cells. Simultaneous addition of F-latex and CpHV-1 to monolayers of MDBK cells resulted in a significant reduction of CpHV-1 titres 3 days post-infection and this effect was comparable to that induced by acyclovir. The study suggests that the F-latex is able to interfere with the replication of CpHV-1 in vitro on MDBK cells and future studies will determine the mechanisms responsible for the observed antiviral activity.

  18. Development of Diagnostic Microscopic and Chemical Markers of Some Euphorbia Latexes

    Institute of Scientific and Technical Information of China (English)

    Uppuluri Venkata Mallavadhani; Kantamreddi Venkata Siva Satyanarayana; Anita Mahapatra; Akella Venkata Subrahmanya Sudhakar; Kilambi Narasimhan; Devendar Kumar Pandey; Manikkannan Thirunavokkarasu

    2006-01-01

    The latexes of the three Euphorbia species, namely E. antiquorum L., E. nerifolia L., and E. tirucalli L., are highly valued in the Indian system of medicine as purgatives, in addition to their specific and distinct therapeutic activities. In order to distinguish these latexes and develop their diagnostic microscopic and chemical markers, we performed extensive chemical and microscopic studies. The three latexes differ significantly in their microscopic features by exhibiting characteristic starch grain patterns. Although amoebic structures were found to be characteristic of E. antiquorum, dumb-bell and oval structures are characteristic of E. nerifolia and E. tirucalli, respectively. In addition, these latexes showed bone-shaped structures as a common feature, but these differed considerably in their length (10-60, 30-55, and 50-70 μm in length in E. antiquorum, E. nerifolia, and E. tirucalli, respectively). The chemical markers nerifoliene and euphol were found to be common to both E. antiquorum and E. nerifolia, whereas euphol is the only marker for E.tirucalli. A reverse-phase high-performance thin-layer chromatographic (HPTLC) method was developed to distinguish these three latexes and to generate their standard fingerprinting patterns. Most significantly,the markers nerifoliene and euphol could be resolved by RP-18 F254s precoated aluminium plates and the latexes have been quantitatively estimated with respect to these markers. The developed microscopic,chemical and HPTLC patterns can be used to distinguish the three latexes.

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

    Science.gov (United States)

    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.

  20. Crosslinking of allergy proteins in natural rubber latex by transglutaminase%生物酶法催化天然乳胶中过敏蛋白质交联的研究

    Institute of Scientific and Technical Information of China (English)

    冯屏; 程必影; 孙金煜; 田晓慧; 王彦超

    2012-01-01

    利用谷氨酰胺转氨酶催化天然乳胶(NRL)水溶性蛋白质(WSP)发生交联,减少天然乳胶中水溶性蛋白质的含量.利用粒径分析、结构表征、十二烷基硫酸钠凝胶电泳实验证明了交联反应的发生.采用这一新技术可以降低天然乳胶制品的过敏性,拓展了其在医疗卫生领域、食品加工等领域的应用空间.%Water-soluble proteins existed in natural rubber latex can easily cause allergic reaction in people. Microbial Transglutaminase (MTGase)can modify latex proteins by means of covalent crosslinking to reduce the content of water-soluble proteins in natural rubber latex. The allergy proteins were considered to be catalysis of crosslinking reaction with MTGase, which were verified by particle-size analysis,characterization of structure and SDS-PAGE. Using this new technology can reduce allergic reaction of natural rubber latex products and expand the application space in the area of health,food processing and other fields.

  1. Two-phase synthesis of olive-like NiS particles and chain-like Bi2S3 nanowires

    Directory of Open Access Journals (Sweden)

    Yuan Yawen

    2015-03-01

    Full Text Available Highly dispersed olive-like NiS particles were synthesized in a liquid-liquid biphasic system at room temperature, where nickel xanthate in organic solvents (toluene and benzene and sodium sulfide in water solution were used as nickel and sulfide sources, respectively. NiS particles were formed at the stabilized phase interface. The structures, chemical composition and optical characteristics of the products were investigated by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. The organic solvents obviously influenced the morphology of the NiS particles. The olive-like NiS with smooth surface and sharp ends was obtained at benzene/water interface, while spindle-like NiS particles with rough surface and circle ends were formed when using toluene as a solvent. Analogously, chainlike Bi2S3 nanowires were produced at chloroform/water interface. The effect of the experiment parameters including reaction time, solvent and concentration of reactants on the size and morphology of the products was discussed in detail and a possible formation mechanism was suggested.

  2. Angiogenic activity of latex from Euphorbia tirucalliLinnaeus 1753 (Plantae, Euphorbiaceae

    Directory of Open Access Journals (Sweden)

    G Bessa

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

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

    Science.gov (United States)

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

    2015-08-01

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

  4. Comparison of latex and haemolysin tests for determination of anti-streptolysin O (ASO) antibodies.

    OpenAIRE

    Curtis, G D; Kraak, W A; Mitchell, R G

    1988-01-01

    A latex agglutination test was compared with the micro-titration haemolysin inhibition method for the detection of anti-streptolysin O (ASO) antibodies in 428 serum samples. After slight modification of the latex method to produce maximal agglutination good agreement was shown between the results obtained by the two methods. The latex test had a sensitivity of 83.6%, a specificity of 93.3%, a predictive positive value of 86.5% and a predictive negative value of 91.6%. It was convenient, requi...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Glove powder's carrying capacity for latex protein: analysis using the ASTM ELISA test.

    Science.gov (United States)

    Beezhold, D; Horton, K; Hickey, V; Daddona, J; Kostyal, D

    2003-01-01

    Glove donning powders carry latex proteins and disperse them into the workplace environment. We have used the ASTM D6499 ELISA to quantify the amount of latex antigen bound to and carried by glove powders. We could differentiate between a small amount of protein actually bound to the powders and a larger amount carried by the powder. Enhanced binding of a major allergen, Hev b 5, to the starch powders was demonstrated by Western blot. The D6499 ELISA is able to measure total latex antigen, soluble and powder bound, simultaneously without the need to centrifuge the samples.

  7. El látex: Un importante aeroalergeno implicado en el asma ocupacional Latex: An important aeroallergen involved in occupational asthma

    Directory of Open Access Journals (Sweden)

    S. Quirce

    2003-01-01

    las manifestaciones de la enfermedad, tiene un mal pronóstico si no se aplican medidas encaminadas a reducir al máximo la exposición al látex.Latex has become one of the most frequent aetiological agents of occupational asthma in the last decade, especially amongst health personnel. The prevalence of occupational asthma due to latex in the different affected occupations varies between 2.5 and 10%, figures that give an idea of the magnitude of the problem. Latex proteins, absorbed in the dust of cornstarch, used as a lubricant, are responsible for asthma due to latex gloves. This cornstarch dust that covers the inside of the gloves acts as a vehicle for dispersing allergenic proteins. Latex aeroallergens are found in particles of different dimensions. The levels of latex aeroallergens in the environment capable of causing sensitization and of unleashing symptoms are not well defined. The determination of these levels of exposure to latex is complicated, since with latex one is dealing with a complex mixture of allergens with differing stability and bio-availability. The bioaerosol of latex is mainly produced by the active use of powdered gloves, but rugs or carpets and coverings act as important reservoirs of the allergen. Besides, the movement of people from areas with a high environmental concentration of latex constitutes an important means of dispersing the allergen, and probably ventilation systems as well. As in other cases of occupational asthma, diagnosis in many cases requires that a bronchial challenge be realized. The specific challenge tests through inhalation with latex have been carried out by different methods, which can be grouped by those that use an aqueous extract of latex and those that consist in handling or shaking gloves, which thus generate a dust aerosol. Each method has its advantages and drawbacks as described. Once the sensitized patient begins manifestations of the disease, his prognosis is poor if measures aimed at a maximum reduction

  8. Impact of the vulcanization process on the structural characteristics and IgE recognition of two allergens, Hev b 2 and Hev b 6.02, extracted from latex surgical gloves.

    Science.gov (United States)

    Galicia, Christian; Mendoza-Hernández, Guillermo; Rodríguez-Romero, Adela

    2015-06-01

    Latex allergy is a health problem that mainly affects medical environments, causing anaphylactic shocks in extreme cases. Sensitization and reactions to this material is closely linked to the use of latex gloves. The objective of this study was to purify two of the major allergens from latex surgical gloves to study the biochemical and structural changes that could be generated during the product manufacture and to compare their IgE recognition with the non-processed allergens. Glycosylated allergen Hev b 2 (β-1,3-glucanase) and Hev b 6.02 (hevein) were purified from glove extracts using affinity (Concanavalin A) and reversed-phase chromatographies, respectively. ELISA experiments were performed with both proteins and sera from allergic patients to assess the IgE recognition, which was heterogeneous. Crystallographic methods were used to obtain the 3D structure of Hev b 6.02 from surgical gloves, which did not show evident modification when compared with the protein from the natural non-processed form. Despite having the same crystallographic structure, the IgE from some patients showed different recognition when the glove and the natural allergen were used in ELISA. Furthermore, using electrophoretic techniques, we identified three forms of Hev b 2: one corresponding to the complete polypeptide chain with posttranslational modifications, and two glycosylated fragments. The mixture of these three forms showed stronger recognition by IgE from latex-allergic patients than the pure non-processed allergen. In conclusion, IgE from subjects sensitized to latex products showed different recognition between the allergens obtained from a natural source and the processed material, even when the structure was maintained. This demonstrates the importance of using processed allergens in further investigations of diagnosis, prevalence, product allergenicity, and therapies.

  9. Falling chains

    Science.gov (United States)

    Wong, Chun Wa; Yasui, Kosuke

    2006-06-01

    The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is incorrect because it neglects the energy gained when a link leaves a subchain. The maximum chain tension measured by Calkin and March for the falling folded chain is given a simple if rough interpretation. Other aspects of the falling folded chain are briefly discussed.

  10. Evaluation of the corrosion resistance of latex modified concrete (LMC)

    Energy Technology Data Exchange (ETDEWEB)

    Okba, S.H.; El-Dieb, A.S.; Reda, M.M. [Ain Shams Univ., Cairo (Egypt). Dept. of Structural Engineering

    1997-06-01

    In recent years, various reinforced concrete structures worldwide have suffered rapid deterioration. Therefore, durability of concrete structures especially those exposed to aggressive environments is of great concern. Many deterioration causes and factors have been investigated. Corrosion of steel reinforcement was found to be one of the major deterioration problems. Penetration of chloride ions is one of the main causes which induces corrosion. The objective of this study is to evaluate the corrosion resistance of latex modified concrete (LMC) compared to conventional concrete using an accelerated corrosion cell. The corrosion cell proved to be a good and simple method to evaluate the durability of concretes especially with respect to chloride ion penetration, and the protection of reinforcement against corrosion. The LMC proved to be superior in its corrosion resistance compared to conventional concrete, which recommends its use in structures exposed to severe aggressive environments.

  11. Plant latex: A natural source of pharmaceuticals and pesticides

    Directory of Open Access Journals (Sweden)

    Ravi K Upadhyay

    2011-01-01

    Full Text Available In recent times use of plant natural products has increased tremendously, and there is a very high demand of herbal products for therapeutic, clinical, agricultural purposes. Plant latex is a rich source of pharmaceuticals, pesticides and immune allergens. It also contains important biomolecules such as glycosides, tannins, phytosterols, Flavonoids, acetogenins and saponins, which show diverse biolgical activities against bacteria, fungi, viruses, protozoans, nematodes, insects, and cancer and tumours. It is also used as disinfectant, anticoagulant, anti-inflammatory, antioxidant and antiproliferative agent that provides protection in wounds. It contains wide variety of industrially important metabolic substances which can be harvested, modified, quenched, and polymerized easily for making goods and materials by up-gradation of technology. No doubt it is a future raw material for many bioengineering and biotechnological industries.

  12. A New Prenylated Xanthone from Latex of Garcinia cowa Roxb.

    Directory of Open Access Journals (Sweden)

    Zhi Na

    2013-05-01

    Full Text Available A new prenylated xanthone, 1,6-dihydroxy-3,7-dimethoxy-2-(3,7-dimethyloct-2,6-dienyl xanthone (3-O-methylcowaxanthone (1, together with four known xanthones, cowaxanthone (2, 7-O-methylgarcinone (3, α-mangostin (4 and γ-mangostin (5 were isolated from the latex of Garcinia cowa. The structure of compound 1 was elucidated on the basis of spectroscopic data interpretation, including 1D and 2D NMR and HREIMS. The cytotoxic activitiy of 1 against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7 and SW480, was evaluated, but it was inactive (IC 50>40μM.

  13. Purification of papain from fresh latex of Carica papaya

    Directory of Open Access Journals (Sweden)

    Rubens Monti

    2000-01-01

    Full Text Available In the present study we wish to report a method of crystallizing papain from fresh papaya latex which gave higher yields than previously reported. This method does not involve the use of sulphydryl reagents. The papain thus obtained is practically pure and shows a single band when submitted to electrophoresis on polyacrylamide gel, and is identical to the papain obtained by other methods. In routine enzymatic assays, specific activity was measured using Z-gly-pNP and BAEE as substrates. Papain crystallized by this method, without the use of high concentrations of salts or thiol-containing substances such as cysteine and dithiothreitol, is obtained in the form of a complex with natural inhibitors existent in latex which can be removed by dialysis.No presente trabalho apresenta-se um método de cristalização da papaína oriunda do látex fresco de mamão, o qual apresenta uma alta produtividade em relação aos métodos previamente descritos. A metodologia aqui descrita não envolve o uso de reagentes sulfidrílicos, a papaína foi obtida de forma praticamente pura, apresentando uma simples banda quando submetida a eletroforese, e com propriedades idênticas àquelas obtidas por outros métodos. A atividade específica foi determinada utilizando Z-gly-pNP e BAEE como substrato. A papaína obtida por essa metodologia, sem uso de substâncias tais como cisteína e ditiotreitol, apresenta-se na forma de um complexo com inibidores naturais, os quais podem ser removidos por diálise.

  14. Acrylic Rubber Latex in Ferrocement for Strengthening Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    D. R. Kumar

    2010-01-01

    Full Text Available Problem statement: In India, the early deterioration of reinforced concrete structures has become a big social problem in recent years. An essential research is needed for the development of effective repair materials and their execution systems comes to an important issue from the viewpoint of the longevity of infrastructures at present. Ferrocement laminates are introduced to enhance the overall performance of Reinforced Concrete (RC structures and these days the use of it is a promising technology for increasing the flexural strength of deficient reinforced concrete members. Approach: The repair system aims to provide quantitative repair enhancement as well as extending the life of deteriorated concrete members. This research in particular inspired the initiation of the present work which aimed to develop a material with unique properties and a very wide range of practical applications. The mechanical properties of mortar through difference in polymer content with Acrilic Latex by ferrocement among three different volume fractions of mesh reinforcement were studied. Following the encouraging progress made in the formulation and evaluation of the polymer modified repair mortar, tests were carried out involving the application of the reinforced repair material to the soffit of the reinforced concrete beams of 3 m length. Results: The levels of damage of the original beams prior to repair did not affect the ultimate load of the strengthened beams tested. The performance of the strengthened beams was compared to the control beams with respect to cracking, deflection and ultimate strength which confirm preeminent results. Conclusion: This accomplished the fact that acrylic rubber latex modified ferrocement is a doable alternative strengthening component for the rehabilitation of reinforced concrete structures. Further developments in these systems will create dramatic improvement into the field of rehabilitation of old privileged structures.

  15. Prevalence of Allergy to Natural Rubber Latex and Potential Cross Reacting Food in Operation Room Staff in Shiraz Hospitals -2006

    Directory of Open Access Journals (Sweden)

    H Nabavizade

    2007-07-01

    Full Text Available Introduction & Objective: Allergic reactions to natural rubber latex have increased during past 10 years especially among health care workers and patients with high exposure to latex allergens. Allergic reaction to latex is related to many diseases like occupational asthma. This study was performed to determine the prevalence of allergy to natural rubber latex and potential cross reacting food in operation room staff in Shiraz hospitals. Materials & Methods: In this cross-sectional descriptive study five hundred eighty operation room staff of ten private and state hospitals in Shiraz completed latex allergy questionnaire. They were questioned about personal history and previous history of latex sensitivity, symptoms of latex reactivity and about other allergies particularly to foods that may cross react with latex. Informed consent was obtained and skin prick testing was performed with natural rubber latex. Skin prick tests were done with three potentially cross reacting food (banana, Kiwi, and potato. The obtained data were analyzed with SPSS software and Chi-square test. Results: Among the 580 operation room workers 104 (17.9 % of participants were positive to latex skin test. We found a significant association between positive skin test to latex in operation room staff and atopy, urticaria and food allergy. Positive skin test to latex related to positive kiwi skin test (p<0.05. The prevalence did not vary by sex, age, education, surgical and non surgical glove users, history of contact dermatitis or smoking status. Conclusion: Latex allergy has a high prevalence in personnel of operation room. Evaluation of present symptom and prediction of future disease necessitate screening test in individuals at risk.

  16. Evaluation of apparent viscosity of Para rubber latex by diffuse reflection near-infrared spectroscopy.

    Science.gov (United States)

    Sirisomboon, Panmanas; Chowbankrang, Rawiphan; Williams, Phil

    2012-05-01

    Near-infrared spectroscopy in diffuse reflection mode was used to evaluate the apparent viscosity of Para rubber field latex and concentrated latex over the wavelength range of 1100 to 2500 nm, using partial least square regression (PLSR). The model with ten principal components (PCs) developed using the raw spectra accurately predicted the apparent viscosity with correlation coefficient (r), standard error of prediction (SEP), and bias of 0.974, 8.6 cP, and -0.4 cP, respectively. The ratio of the SEP to the standard deviation (RPD) and the ratio of the SEP to the range (RER) for the prediction were 4.4 and 16.7, respectively. Therefore, the model can be used for measurement of the apparent viscosity of field latex and concentrated latex in quality assurance and process control in the factory.

  17. Preparation of Styrene-acrylate Latex Used in Ultra-low VOC Building Internal Wall Coating

    Institute of Scientific and Technical Information of China (English)

    CHEN Lijun; WU Fengqin; ZHUANG Xinyu; YANG Jian; LI Rongxian

    2008-01-01

    Styrene-acrylate latex with high glass transition temperature(Tg),low minimum film forming temperature(MFT)and good stability was prepared via core-shell emulsion polymerization.With semicontinuous process,high conversion rate of monomer and low gel rate were achieved.The weight ratio of core monomer to shell monomer was approximately 1.35.It is found that many factors such as emulsifiers,initiators,reaction temperature,pH value and polymerization technology have influences on the permormance of styrene-acrylate latex.The prepared latex was characterized by TEM and FTIR.The obtained latex with T of20.57℃,MFT of 5.0℃,and good stability,had good stability of film forming.

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

    Science.gov (United States)

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

    2012-08-01

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

  19. Maillard Reaction in Natural Rubber Latex: Characterization and Physical Properties of Solid Natural Rubber

    Directory of Open Access Journals (Sweden)

    S. Montha

    2016-01-01

    Full Text Available Maillard reaction in Natural Rubber (NR latex was investigated by treating fresh NR latex with glutaraldehyde (C5H8O2 in amounts of 0, 50, 100, and 200 mmol/kg of latex. Protein cross-linking in fresh NR latex and solid NR was confirmed by using sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE and attenuated total reflection infrared (ATR-IR spectroscopy, respectively. It was found that degree of protein cross-linking in NR increased with increasing C5H8O2 concentration. Physical properties of untreated and treated NR substances in terms of gel content, initial Wallace plasticity (P0, plasticity retention index (PRI, Mooney viscosity, and tensile strength were carefully explored. Results clearly showed that the Maillard cross-linking of proteins had remarkable effect on bulk NR properties, that is, solvent resistance, hardness, resistance to oxidation, rheological behavior, and resistance to stretching out.

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

    Science.gov (United States)

    1986-07-01

    Examples of polymers used as latex admixtures for concrete and mor- tar in the United States are PVA, styrene-butadiene, polyacrylates (acrylics), and...the substrate by removing all loose and disintegrating material. Oil, grease, or other chemicals should be re- moved with a detergent , and the... detergent should be removed by several wash- ings with water. Because of the surface film characteristics of a latex mixture, the mortar should be placed as

  1. MathPSfrag 2: Convenient LaTeX Labels in Mathematica

    CERN Document Server

    Große, Johannes

    2008-01-01

    This article introduces the next version of MathPSfrag. MathPSfrag is a Mathematica package that during export automatically replaces all expressions in a plot by corresponding LaTeX commands. The new version can also produce LaTeX independent images; e.g., PDF files for inclusion in pdfLaTeX. Moreover from these files a preview is generated and shown within Mathematica.

  2. Reinforcement of natural rubber latex with silica modified by cerium oxide:preparation and properties

    Institute of Scientific and Technical Information of China (English)

    张福全; 廖禄生; 王永周; 汪月琼; 黄红海; 李普旺; 彭政; 曾日中

    2016-01-01

    Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibility of SiO2-CeO2 with rubber matrix, then SiO2-CeO2 modified by CTAB and curing formulas were mixed with fresh natural rubber (NR) latex to prepare NR/SiO2-CeO2 nanocomposites that contained 0–10 parts of CeO2 by a new emulsion compounding method. The morphologies, cure characteristics, mechanical properties and thermal-oxidative stability of NR/SiO2-CeO2 nanocomposites were investigated. The re-sults revealed that the presence of CeO2 in NR/SiO2-CeO2nanocomposites was favorable for enhancing the interaction between NR matrix and fillers, helped to get smaller SiO2-CeO2 particles with narrower particle size distribution, further improved the crosslink densities and mechanical properties of NR/SiO2-CeO2 nanocomposites vulcanizates. Meanwhile, the addition of CeO2 increased the active energy at least 4.66%, obviously improved the thermal-oxidative aging-inhibiting properties of NR/SiO2-CeO2 nanocomposites. Additionally, nanocomposites containing CeO2 promotedTg shift to high temperature direction, causing the nanocomposites featured higher tanδ at 0 ºC and lower tanδ at 60 ºC and exhibited comparable wet grip and lower rolling resistance when NR/SiO2-CeO2nano-composites were used in tire tread compound.

  3. Unwrapping Chains

    CERN Document Server

    Cambou, A D; Hamm, E; Hanna, J A; Menon, N; Santangelo, C D; Walsh, L

    2012-01-01

    A loop of chain can move along its own tangents, maintaining a steady shape. An open-ended chain undergoing a nontrivial motion must change its shape. One consequence is that chains pulled around objects will fail to follow the contours of the objects, unwrapping themselves instead. This short note accompanies a fluid dynamics video submission (83068) to the APS DFD Gallery of Fluid Motion 2012.

  4. Falling chains

    CERN Document Server

    Wong, C W; Wong, Chun Wa; Yasui, Kosuke

    2006-01-01

    The one-dimensional falling motion of a bungee chain suspended from a rigid support and of a chain falling from a resting heap on a table is studied. Their Lagrangians are found to contain no explicit time dependence. As a result, these falling chains are conservative systems. Each of their Lagrange's equations of motion is shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show in particular that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is incorrect because it neglects the energy gained when the transferred link is emitted by the emitting subchain. The maximum chain tension measured by Calkin and March for the falling bungee chain is given a simple if rough interpretation. In the simplified one-dimensional treatment, the kinetic energy of the center of mass of the falling bungee chain is found to be converted by the chain tension at the rigid support into the internal kinetic energy of the chain. However, as t...

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

    Science.gov (United States)

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

    2015-01-01

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

  6. Effects of Euphorbia milii latex on mitogen-induced lymphocyte proliferation

    Directory of Open Access Journals (Sweden)

    I.F. Delgado

    2014-03-01

    Full Text Available The crude latex of "Crown-of-Thorns" (Euphorbia milii var hislopii, syn E.splendens is a potent plant molluscicide. For this reason, toxicological studies have been performed to evaluate the health risks posed by its use in schistosomiasis control programs. The present study is part of a more comprehensive immunotoxicological evaluation of this molluscicide. Here, we investigated the effects of E. milii latex on the proliferation of human lymphocytes in vitro. Lyophilized latex of E. milii (0, 0.5, 5, 25 and 50 µg/ml was incubated with whole blood in the presence of proliferation stimulators, i.e. lectins (phytohemagglutinin, concanavalin A and pokeweed mitogen, as well as with human monoclonal antibody against CD3 and tetanus toxoid. Cell proliferation was measured by ³H-thymidine incorporation, and the effects of latex on mitogen-induced cell proliferation were compared to the effects of 10 ng/ml of 12-O-tetradecanoylphorbol-13-acetate (TPA. Results showed that mitogen-induced cell proliferation was markedly enhanced by E. milii latex. This synergistic effect of latex on mitogen-induced lymphocyte proliferation may be due to the presence of TPA-like phorbol esters and/or to mitogenic plant lectins.

  7. Histamine mediates the pro-inflammatory effect of latex of Calotropis procera in rats.

    Science.gov (United States)

    Shivkar, Yatin M; Kumar, Vijay L

    2003-01-01

    INTRODUCTiON: Calotropis procera is known to produce contact dermatitis and the latex of this plant produces intense inflammation when injected locally. However, the precise mode of its pro-inflammatory effect is not known. In present study we have pharmacologically characterized the inflammation induced by latex of C. procera in a rat paw edema model and determined the role of histamine in latex-induced inflammation. METHODS: Inflammation was induced in the hind paw of rats by injecting different doses of dried latex (DL) of C. procera. The inhibitory effect of phenylbutazone, dexamethasone, celecoxib, cyproheptadine, chlorpheniramine and compound 48/80 on edema volume was evaluated and compared with that against carrageenan. The histamine content of DL was measured fluorometrically. RESULTS: DL produced dose-dependent inflammation of the rat paw. Cyproheptadine and chlorpheniramine effectively inhibited DL-induced inflammation (90%; p phenylbutazone, dexamethasone and celecoxib were more effective against carrageenan-induced inflammation. Depletion of mast cell histamine by compound 48/80 produced a significant decrease in DL-induced inflammation as compared with carrageenan (500% versus 25%). DL was also found to contain about 6 microg/g of histamine. CONCLUSIONS: Thus, our study shows that the biogenic amines play a significant role in C. procera latex-induced inflammation and antihistaminic drugs could be effectively used to inhibit inflammatory response elicited by exposure to latex. PMID:14760937

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

    Directory of Open Access Journals (Sweden)

    Donnan Alison A

    2011-03-01

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

  9. Sensitization from chestnuts and bananas in patients with urticaria and anaphylaxis from contact with latex.

    Science.gov (United States)

    Fernández de Corres, L; Moneo, I; Muñoz, D; Bernaola, G; Fernández, E; Audicana, M; Urrutia, I

    1993-01-01

    We present eight patients allergic to latex and fruit (chestnut and banana), seven of whom are women, and aged 17 to 42 years (mean 25 years). Four had family and five personal atopic histories. The total IgE varied from 41 to 520 Ku/L (mean 263). The symptoms followed ingestion of fruit (anaphylaxis) in four patients and contact with rubber (contact urticaria and anaphylaxis) in the other four. Skin prick test (SPT) with latex and radioallergosorbent test to latex were positive in all the patients. Histamine release (HR) to latex was carried out on six patients and was positive in three. In the six patients with symptoms after having eaten chestnuts the SPT was positive and specific IgE was detected in five of them. Histamine release to chestnuts was positive in three of the six patients tested and one of them (-SPT and + IgE) tolerated the fruit. Two out of five patients with symptomatic banana allergy had negative SPT with banana while the test was positive in one patient who tolerated this fruit, this being the only case with specific IgE to banana. Histamine release with banana was only positive in one case. The important correlation between SPT, RAST, and HR results to latex and chestnut together with the total inhibition of the chestnut RAST with a serum pool by preincubation with latex suggests cross-reactivity among these allergens.

  10. Particle separations by electrophoretic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ballou, N.E.; Petersen, S.L.; Ducatte, G.R.; Remcho, V.T.

    1996-03-01

    A new method for particle separations based on capillary electrophoresis has been developed and characterized. It uniquely separates particles according to their chemical nature. Separations have been demonstrated with chemically modified latex particles and with inorganic oxide and silicate particles. Separations have been shown both experimentally and theoretically to be essentially independent of particle size in the range of about 0.2 {mu}m to 10 {mu}m. The method has been applied to separations of U0{sub 2} particles from environmental particulate material. For this, an integrated method was developed for capillary electrophoretic separation, collection of separated fractions, and determinations of U0{sub 2} and environmental particles in each fraction. Experimental runs with the integrated method on mixtures of UO{sub 2} particles and environmental particulate material demonstrated enrichment factors of 20 for UO{sub 2} particles in respect to environmental particles in the U0{sub 2}containing fractions. This enrichment factor reduces the costs and time for processing particulate samples by the lexan process by a factor of about 20.

  11. A fiber-optic probe for particle sizing in concentrated suspensions

    Science.gov (United States)

    Dhadwal, Harbans S.; Ansari, Rafat R.; Meyer, William V.

    1991-01-01

    A fiber-optic probe employing two monomode optical fibers, one for transmitting a Gaussian laser beam to the scattering volume and the second, positioned at some backscatter angle, for receiving the scattered light is described. Performance and suitability of the system for a process control environment is assessed by studying a suspension of polystyrene latex particles over a wide range of sizes and concentrations. The results show that the probe is ideal for a process control environment in industrial and laboratory applications. Particle size is recovered, without any additional corrections for multiple light scattering, in concentrations containing up to 10 percent solids of 39-nm polystyrene latex spheres.

  12. EFFECT of blend ratio and compatibilizer on solution casted treated waste natural rubber latex/polystyrene blends

    OpenAIRE

    Orathai Boondamnoen; A. Rashid Azura; Masahiro Ohshima; Saowaroj Chuayjuljit; Azlan Ariffin

    2013-01-01

    Natural rubber latex waste (WL) was treated with natural rubber latex (NRL) prior to blend with polystyrene. Differentblend compositions of treated waste natural rubber latex (TWL) and PS were carried out through solution blending. Tensileand tear properties were investigated. The compatibility improvement of the 70/30 TWL/PS blends was further investigatedusing styrene butadiene rubber (SBR) and styrene graft natural rubber (SNR) as compatibilizer. The mechanical properties forTWL/PS blends ...

  13. Identification and biochemical characterization of a GDSL-motif carboxylester hydrolase from Carica papaya latex.

    Science.gov (United States)

    Abdelkafi, Slim; Ogata, Hiroyuki; Barouh, Nathalie; Fouquet, Benjamin; Lebrun, Régine; Pina, Michel; Scheirlinckx, Frantz; Villeneuve, Pierre; Carrière, Frédéric

    2009-11-01

    An esterase (CpEst) showing high specific activities on tributyrin and short chain vinyl esters was obtained from Carica papaya latex after an extraction step with zwitterionic detergent and sonication, followed by gel filtration chromatography. Although the protein could not be purified to complete homogeneity due to its presence in high molecular mass aggregates, a major protein band with an apparent molecular mass of 41 kDa was obtained by SDS-PAGE. This material was digested with trypsin and the amino acid sequences of the tryptic peptides were determined by LC/ESI/MS/MS. These sequences were used to identify a partial cDNA (679 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 1029 bp encoding a protein of 343 amino acid residues, with a theoretical molecular mass of 38 kDa. From sequence analysis, CpEst was identified as a GDSL-motif carboxylester hydrolase belonging to the SGNH protein family and four potential N-glycosylation sites were identified. The putative catalytic triad was localised (Ser(35)-Asp(307)-His(310)) with the nucleophile serine being part of the GDSL-motif. A 3D-model of CpEst was built from known X-ray structures and sequence alignments and the catalytic triad was found to be exposed at the surface of the molecule, thus confirming the results of CpEst inhibition by tetrahydrolipstatin suggesting a direct accessibility of the inhibitor to the active site.

  14. 微波辐射制备室温自交联含氟聚丙烯酸酯乳液%Preparation of room temperature self-crosslinking fluorinated polyacrylate latex under microwave radiation

    Institute of Scientific and Technical Information of China (English)

    严微; 黄丽君; 王丽; 徐明; 徐祖顺

    2012-01-01

    Room temperature self-crosslinking fluorinated polyacrylate latex was prepared under microwave irradiation with dodecafluoroheptyl methacrylate (DAAM) as fluorine-containing monomer, diactone acrylamide as functional monomer, adipic dihydrazide as crosslinking agent, anionic sodium dodecyl sulfate and non-ionic aliphatic alcohol polyoxyethylene ether as composite emulsifier, and potassium persulfate as initiator. The impact of the crosslinking monomer amount on the conversion of monomers, particle size distribution and its index of the latex and water absorption of the latex film were studied. The latex formed in the shape of spherical particles with average diameter of 60-70 nm when the mass content of DAAM was 5%. As the DAAM content augmented the water absorption of the latex film decreased and in the meantime, the crosslinking played a leading role. However, if the DAAM content continued to rise, the water absorption of the latex film increased instead meanwhile the hydrophilic property took over the dominant role.%在微波辐射下,以甲基丙烯酸十二氟庚酯(DAAM)为含氟单体,双丙酮丙烯酰胺为功能单体,己二酸二酰肼为交联剂,阴离子十二烷基硫酸钠和非离子脂肪醇聚氧乙烯醚为复合乳化剂,在过硫酸钾的引发下,制备了可室温自交联的含氟聚丙烯酸酯乳液.考察了交联单体用量对转化率、粒径分布及分布指数和乳胶膜吸水率的影响.w(DAAM)为5%时,乳液乳胶粒呈球形,平均粒径在60~70 nm.随着DAAM用量的增加,乳胶膜吸水率减小,此时交联起主导作用;进一步增加DAAM用量,乳胶膜吸水率反而增大,此时亲水性起主导作用.

  15. Changes in chemical permeation of disposable latex, nitrile, and vinyl gloves exposed to simulated movement.

    Science.gov (United States)

    Phalen, Robert N; Le, Thi; Wong, Weng Kee

    2014-01-01

    Glove movement can affect chemical permeation of organic compounds through polymer glove products. However, conflicting reports make it difficult to compare the effects of movement on chemical permeation through commonly available glove types. The aim of this study was to evaluate the effect of movement on chemical permeation of an organic solvent through disposable latex, nitrile, and vinyl gloves. Simulated whole-glove permeation testing was conducted using ethyl alcohol and a previously designed permeation test system. With exposure to movement, a significant decrease (p ≤ 0.001) in breakthrough time (BT) was observed for the latex (-23%) and nitrile gloves (-31%). With exposure to movement, only the nitrile glove exhibited a significant increase (p ≤ 0.001) in steady-state permeation rate (+47%) and cumulative permeation at 30 min (+111%). Even though the nitrile glove provided optimum chemical resistance against ethyl alcohol, it was most affected by movement. With exposure to movement, the latex glove was an equivalent option for overall worker protection, because it was less affected by movement and the permeation rate was lower than that of the nitrile glove. In contrast, the vinyl glove was the least affected by movement, but did not provide adequate chemical resistance to ethyl alcohol in comparison with the nitrile and latex gloves. Glove selection should take movement and polymer type into account. Some glove polymer types are less affected by movement, most notably the latex glove in this test. With nitrile gloves, at least a factor of three should be used when attempting to assign a protection factor when repetitive hand motions are anticipated. Ultimately, the latex gloves outperformed nitrile and vinyl in these tests, which evaluated the effect of movement on chemical permeation. Future research should aim to resolve some of the observed discrepancies in test results with latex and vinyl gloves.

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

    Science.gov (United States)

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

    2014-03-01

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

  17. Latex nanoparticles for multimodal imaging and detection in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Cartier, R [Clinic for Anaesthesiology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Kaufner, L [Clinic for Anaesthesiology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Paulke, B R [Fraunhofer Institute for Applied Polymer Research, Potsdam (Germany); Wuestneck, R [Clinic for Anaesthesiology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Pietschmann, S [Clinic for Anaesthesiology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Michel, R [Department of Radiology, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Bruhn, H [Department of Radiology, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany); Pison, U [Clinic for Anaesthesiology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin University Medical School, Berlin (Germany)

    2007-05-16

    The aim of the present work was to develop a multimodal imaging and detection approach to study the behaviour of nanoparticles in animal studies. Highly carboxylated 144 nm-sized latex nanoparticles were labelled with {sup 68}Ga for positron emission tomography, {sup 111}In for quantitative gamma scintigraphy or Gd{sup 3+} for magnetic resonance imaging. Following intravenous injection into rats, precise localization was achieved revealing the tracer in the blood compartment with a time-dependent accumulation in the liver. In addition, rhodamine B was also incorporated to examine specific interactions with blood cells. Flow cytometry and fluorescent microscopy show uptake of nanoparticles by leucocytes and, unexpectedly, thrombocytes, but not erythrocytes. Cellular internalization was an active and selective process. Further incorporation of polyethylene glycol into the nanoparticle corona could prevent uptake by thrombocytes but not macrophages or monocytes. Our data demonstrate the feasibility of a multimodal approach and its usefulness to analyse the fate of nanoparticles at the macroscopic and cellular level. It will facilitate the development of functionalized nanocarrier systems and extend their biomedical applications.

  18. Fully mechanized latex immunoassay for serum lipoprotein(a).

    Science.gov (United States)

    Abe, A; Yoshimura, Y; Sekine, T; Maeda, S; Yamashita, S; Noma, A

    1994-03-01

    We have developed a fully automated system to quantify lipoprotein(a) (Lp(a)) in human serum, based on the latex-enhanced turbidimetric immunoassay by application of the Immuno Chemistry Analyzer 501X. This assay was carried out with undiluted serum and was able to detect at Lp(a) levels higher than 4.0 mg/l. When judged to be out of range of the calibration (> 600 mg/l), the sample was automatically re-tested after automatic 10-fold dilution. Within-run C.V.s ranged from 1.9 to 2.1% and between-run C.V.s from 2.7 to 3.9%. Results by the present method were in good agreement with those by the in-house ELISA (r = 0.978) and the commercial ELISA (r = 0.990). The distribution of Lp(a) levels in sera from 508 healthy donors was highly skewed; the mean and median were 158 mg/l and 105 mg/l, respectively.

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Whole-Chain Tick Saliva Proteins Presented on Hepatitis B Virus Capsid-Like Particles Induce High-Titered Antibodies with Neutralizing Potential.

    Directory of Open Access Journals (Sweden)

    Philipp Kolb

    Full Text Available Ticks are vectors for various, including pathogenic, microbes. Tick saliva contains multiple anti-host defense factors that enable ticks their bloodmeals yet also facilitate microbe transmission. Lyme disease-causing borreliae profit specifically from the broadly conserved tick histamine release factor (tHRF, and from cysteine-rich glycoproteins represented by Salp15 from Ixodes scapularis and Iric-1 from Ixodes ricinus ticks which they recruit to their outer surface protein C (OspC. Hence these tick proteins are attractive targets for anti-tick vaccines that simultaneously impair borrelia transmission. Main obstacles are the tick proteins´ immunosuppressive activities, and for Salp15 orthologs, the lack of efficient recombinant expression systems. Here, we exploited the immune-enhancing properties of hepatitis B virus core protein (HBc derived capsid-like particles (CLPs to generate, in E. coli, nanoparticulate vaccines presenting tHRF and, as surrogates for the barely soluble wild-type proteins, cysteine-free Salp15 and Iric-1 variants. The latter CLPs were exclusively accessible in the less sterically constrained SplitCore system. Mice immunized with tHRF CLPs mounted a strong anti-tHRF antibody response. CLPs presenting cysteine-free Salp15 and Iric-1 induced antibodies to wild-type, including glycosylated, Salp15 and Iric-1. The broadly distributed epitopes included the OspC interaction sites. In vitro, the anti-Salp15 antibodies interfered with OspC binding and enhanced human complement-mediated killing of Salp15 decorated borreliae. A mixture of all three CLPs induced high titered antibodies against all three targets, suggesting the feasibility of combination vaccines. These data warrant in vivo validation of the new candidate vaccines´ protective potential against tick infestation and Borrelia transmission.

  1. A "test of concept" comparison of aerodynamic and mechanical resuspension mechanisms for particles deposited on field rye grass ( Secale cercele). Part 1. Relative particle flux rates

    Science.gov (United States)

    Gillette, Dale A.; Lawson, Robert E.; Thompson, Roger S.

    Resuspension of uniform latex micro spheres deposited on a single seed pod of field rye grass stalk and head was investigated experimentally in a wind tunnel. The experiment was designed to distinguish aerodynamic (viscous and turbulent) mechanisms from mechanical resuspension resulting from the oscillatory impact of the grass hitting a stationary object. The experiment was run for deposited spherical latex particles with diameters from 2 to 10 μm. Wind tunnel tests were run for wind speeds from 2 to 18.5 m s -1 and a turbulence intensity (root-mean-square fluctuation wind speed/mean wind speed) of 0.1. Our experiments showed the following for our test of concept experiment: Resuspension particle flux increases when mechanical impacts occur. Mechanical resuspension dominated for 2 μm particles over purely aerodynamic resuspension, but for larger particles aerodynamic mechanisms were roughly equally effective in resuspending particles.

  2. Conventional rapid latex agglutination in estimation of von Willebrand factor: method revisited and potential clinical applications.

    Science.gov (United States)

    Mahat, Marianor; Abdullah, Wan Zaidah; Hussin, Che Maraina Che

    2014-01-01

    Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to 150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag.

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

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, R.G.; Hinkebein, T.E.; Hlava, P.F. [Sandia National Labs., Albuquerque, NM (United States); Melton, D.G. [LaQue Center for Corrosion Technology, Inc., Wrightsville Beach, NC (United States)

    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.

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

    Science.gov (United States)

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

    2015-02-05

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

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

    Science.gov (United States)

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

    2014-07-01

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

  6. Jatropha curcas latex inhibits the release of collagenase by gingival fibroblast

    Directory of Open Access Journals (Sweden)

    Fazwishni Siregar

    2007-12-01

    Full Text Available Folkloric use of J. curcas latex among others are to cure tooth pain, bleeding gum and as anti-inflammatory drug. Collagenase is a neutral protease released by activated macrophage and also by fibroblasts in small amounts. The aim of this study was to evaluate the effect of J. curcas latex on collagenase released by fibroblasts. Four doses of J. curcas latex from 37.5-300 g/ml were added to 3 human gingival primary fibroblast cell culture. After 1 to 4 days of incubation, collagenase in the supernatant was assayed with collagen. The degradation products were then separated by SDS-PAGE and the density of ¾ A bands were measured semi quantitatively by Adobe Photo computer program. Result showed that J. curcas latex decreased collagenase released by human gingival fibroblast, and increasing dose inhibits more. It may be concluded that the latex of J. curcas inhibits the release of collagenase by human gingival fibroblast. (Med J Indones 2007; 16:219-23Keywords: Jatropha curcas, collagenase, human gingival fibroblast, collagenase assay, SDS-PAGE

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

    Science.gov (United States)

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

    2015-02-01

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

  8. In situ generated silica in natural rubber latex via the sol–gel technique and properties of the silica rubber composites

    Energy Technology Data Exchange (ETDEWEB)

    Poompradub, Sirilux, E-mail: sirilux.p@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Thirakulrati, Mantana [Program in Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Prasassarakich, Pattarapan [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand)

    2014-03-01

    Natural rubber (NR) composites reinforced by silica generated in situ within the NR matrix were prepared by the sol–gel process using tetraethoxysilane (TEOS) as the silica precursor. The effect of the TEOS content, water: TEOS mole ratio, reaction time and temperature on the in situ silica content formed in the NR latex were investigated. The results indicated that the suitable condition to produce a high silica content (54 parts by weight per hundred parts of rubber (phr)) in the rubbery matrix was the use of 200 phr TEOS and a water: TEOS mole ratio of 28.9:1 at room temperature for 24 h. The curing, mechanical, and thermal properties of the composite materials were also investigated. Increasing the in situ silica content increased the cure time and improved the mechanical properties of the composite. Compared to the NR vulcanizates filled with the commercial (ex situ formed) silica, the mechanical and thermal properties of the in situ silica composite material were significantly improved. Transmission electron microscopy revealed that the in situ formed silica particles were well distributed within the NR matrix, in contrast to the clumping of the ex situ formed commercial silica within the NR matrix. - Highlights: • High in situ silica content in NR latex was obtained up to 54 phr. • A good dispersion of in situ silica filling into the rubbery matrix. • Comparison of silica generated in the rubber matrix using solid, solution and latex NR substrates. • A good reinforcement effect of in situ silica was observed on the NR vulcanizate. • Sol–gel method is an alternative way to develop a novel composite material.

  9. 丝胶接枝物改性天然乳胶的研究%Research of using silk sericin to modify natural rubber latex

    Institute of Scientific and Technical Information of China (English)

    孙金煜; 田晓慧; 元以中; 龚淑婷; 冯佼姣; 刘虎邱

    2011-01-01

    利用丝胶优良的抗氧化性和亲肤性等特点,将丝胶包覆在天然乳胶粒表面,从而隔绝了天然乳胶膜与皮肤的直接接触,改善天然乳胶制品对皮肤的过敏性反应,使其不仅具有耐氧化性,而且与皮肤接触后可有效防止肌肤干燥,抑制肌肤黑色素生成等.同时将水性聚氨酯通过先接枝后杂凝聚的方法,在不改变乳胶断裂伸长率的情况下,提高拉伸强度,实现了对天然乳胶过敏性和机械性能的双重改善.%By the use of excellent oxidation resistance and skin friendly of silk sericin, silk sericin coats the surface of natural rubber latex particles which could cut off the direct contact with the skin and improve allergy. It makes natural latex rubber could not only resist oxidation but also effectively avoid skin drying and prevent melanin' s generating. After heterocoagulating with aqueous polyure-thane grafting with silk sericin, natural rubber latex membrane could improve fracture strength without reducing its breaking elongation,realize the improvement of its anaphylaxis and mechanical properties.

  10. Universal Virus Adsorption on Inert Particles Utilizing the Coated Latex Adsorption Method (CLAM)

    Science.gov (United States)

    1975-06-30

    autoimmune processes such as autoimmune hemolytic anemia or erythro- blastosis fetalis. Cell mediated immunity includes graft rejection, delayed hyper...activated antigen-primed cellst A computer simulation. J. Immunol. 107:115-122. 18. Conrad, R. E. and J. S. Ingraham. 1974. Rate of hemolytic anti- body...infected; and the rate of removal of infected virus. This information is of great value in the diagnosis of viral infection under natural conditions

  11. Preparation of multihollow P(St-MAA) particles by sequence soap-free/soap emulsion polymerization and followed by stepwise alkali/acid posttreatment

    Institute of Scientific and Technical Information of China (English)

    Rong Long Li; Cheng You Kan; Ze Ping Li; Yi Du; Yan Nan Cui

    2007-01-01

    The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated.The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA).Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization.

  12. Construction and Validation of a Self-Efficacy Scale for Latex Barrier Use.

    Science.gov (United States)

    Morell-Mengual, Vicente; Gil-Llario, María Dolores; Castro-Calvo, Jesús

    2016-03-22

    Some studies have concluded there is a relationship between perceived self-efficacy and behaviors that prevent HIV transmission. This paper presents the construction and validation of the latex barrier use self-efficacy scale (LBSS), which 480 participants filled out. Exploratory factor analysis yielded two components: positive expectations of self-efficacy (ES-POS) and negative expectations of self-efficacy (ES-NEG), which together accounted for 65.59% of total variance. That structure was later verified through confirmatory factor analysis. Internal consistency was .80 for the total scale, and .78 for each of the two factors. Moreover, the instrument had adequate convergent validity and was positively related with condom use self-efficacy, attitudes toward condom and latex barrier use, and ability to refuse sex if the partner refuses to use preventive methods. In conclusion, this instrument is a useful measure of self-efficacy in latex barrier use.

  13. Status of latex industry%国内外胶乳行业发展现状

    Institute of Scientific and Technical Information of China (English)

    席莺; 李旭祥

    2001-01-01

    介绍了国内外胶乳行业的发展现状,讨论了由 于胶乳制品存在蛋白质和添加剂造成过敏以及致癌物亚硝胺的析出的解决办法,同时介绍了 天然胶乳、合成胶乳的应用领域及发展方向。%The present status of latex industry was introduced.The a llergy caused by protein and additive in natural latex and the precipitation of nitrosamine were discussed and several resolvents were put forward.The applicati on area and the developments of natural and synthetic latex were also introduce d.

  14. 苯丙-硅溶胶纳米复合乳液的制备及其性能%Study on polymerization and performance of styrene acrylate/silica nanocomposite latex

    Institute of Scientific and Technical Information of China (English)

    嵇胜全; 孔凡桃; 朱爱萍; 钟涛; 钱晓燕

    2011-01-01

    采用原位乳液聚合法制备了苯丙-硅溶胶纳米复合乳液,系统研究了乳化剂种类和用量对乳液稳定性、乳胶膜吸水率以及乳胶粒子粒径的影响.结果表明:相比单独使用,十二烷基硫酸钠(SDS)与壬基酚聚氧化乙烯基醚(OP-10)按质量比为2:1复配时制备的乳液稳定性最好;当乳化剂用量为0.75%~1.5%时,所制复合乳液稳定性好,乳胶膜的吸水率为3.64%~5.72%.与共混乳液(硅溶胶和苯丙乳液的共混物)和苯丙乳液的乳胶膜相比,复合乳胶膜的吸水率显著降低;透射电子显微镜(TEM)检测结果表明:与共混乳液相比,复合乳液中游离的纳米SiO2粒子数大大减少.%The styrene-acrylate/silica nanocomposite latex was synthesized by in-situ emulsion polymerization. The influence of the type and content of emulsifier on the emulsion polymerization stabilities, water absorption rate of latex film and the size of the latex were studied systematically. The results indicated that the emulsion polymerization stabilities were best when the emulsifier of SDS and OP-10 were used with a mass ratio of 2 : 1; when the emulsifier content used was in the range of 0. 75%~l. 5%, the obtained latex showed good stability and the water absorption rate was as low as 3. 64%~5. 72%. The nanocomposite latex film showed lower water absorption rate than those formed by the pure styrene-acrylic emulsion and the physical mixture of styrene-acrylic emulsion and silica sol. The TEM results showed that the number of free SiO2 particles in nanocomposite latex was much less than that in the mixture of styrene-acrylic emulsion and silica sol.

  15. [Evaluation of latex agglutination test for anti-treponemal antibody in comparison with chemical luminescence tests].

    Science.gov (United States)

    Watanabe, Naomi; Nagatomo, Ritsuko; Okubo, Shigeo; Yokota, Hiromitsu; Ikeda, Hitoshi; Yatomi, Yutaka

    2011-02-01

    The performance of a latex agglutination test (Mediace TPLA) in the detection of anti-treponemal antibody was evaluated in comparison with chemical luminescence tests (LumipulsII-N and Architect TPAb) in 346 cases. Anti-treponemal antibody was further determined by immunochromatography and immunoblotting tests and additionally evaluated by a serological test for syphilis with lipoidal antigens. The total concordance rate between the latex agglutination test and chemical luminescence tests ranged from 96% to 97%: the positive concordance rate ranged from 96% to 97%, and the negative concordance rate, from 97% to 98%. The latex agglutination test showed two false positive cases, and each chemical luminescence test showed two false positive cases, respectively. In eight cases, only the latex agglutination test showed negative results; all specimens contained anti-treponemal antibodies. However, none of these was considered to be a false positive and each was treated as syphilis based on the results of confirmatory analysis with immunochromatography and immunoblotting tests and a serological test for syphilis. The discordant results in the latex agglutination test and chemical luminescence tests may be caused by the different antigenisity of each test. With detailed analysis of those sera treated as syphilis, each specimen was found to contain various antibodies against syphilitic antigens, suggesting that there was a different specificity of native and recombinant antigens. Based on the present results for the comparison between the latex agglutination test and chemical luminescence tests, it was considered that further investigation is necessary to clarify the anti-treponemal antibody profile of syphilis at the disease stage.

  16. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    Energy Technology Data Exchange (ETDEWEB)

    Määttänen, Anni, E-mail: anni.maattanen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Ihalainen, Petri, E-mail: petri.ihalainen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Törngren, Björn, E-mail: bjorn.torngren@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Rosqvist, Emil, E-mail: emil.rosqvist@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Pesonen, Markus, E-mail: markus.pesonen@abo.fi [Physics, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Peltonen, Jouko, E-mail: jouko.peltonen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland)

    2016-02-28

    Graphical abstract: - Highlights: • Transparent self-supported latex films were fabricated by a peel-off process. • Various template substrates were used for creating e.g. hierarchically structured latex films. • Ultra-thin and semi-transparent conductive gold electrodes were evaporated on the latex films.Electrochemical experiments were carried out to verify the applicability of the electrodes. - Abstract: Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV–vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH{sub 2}){sub 11}OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal

  17. Chain Gang

    Science.gov (United States)

    2006-01-01

    6 August 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a chain of clustered and battered craters. These were formed by secondary impact. That is, somewhere to the south (beyond the bottom of this image), a large impact crater formed. When this occurred, material ejected from the crater was thrown tens to hundreds of kilometers away. This material then impacted the martian surface, forming clusters and chains of smaller craters. Location near: 15.8oN, 35.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Northern Spring

  18. Deposition of latex colloids at rough mineral surfaces: an analogue study using nanopatterned surfaces.

    Science.gov (United States)

    Krishna Darbha, Gopala; Fischer, Cornelius; Michler, Alex; Luetzenkirchen, Johannes; Schäfer, Thorsten; Heberling, Frank; Schild, Dieter

    2012-04-24

    Deposition of latex colloids on a structured silicon surface was investigated. The surface with well-defined roughness and topography pattern served as an analogue for rough mineral surfaces with half-pores in the submicrometer size. The silicon topography consists of a regular pit pattern (pit diameter = 400 nm, pit spacing = 400 nm, pit depth = 100 nm). Effects of hydrodynamics and colloidal interactions in transport and deposition dynamics of a colloidal suspension were investigated in a parallel plate flow chamber. The experiments were conducted at pH ∼ 5.5 under both favorable and unfavorable adsorption conditions using carboxylate functionalized colloids to study the impact of surface topography on particle retention. Vertical scanning interferometry (VSI) was applied for both surface topography characterization and the quantification of colloidal retention over large fields of view. The influence of particle diameter variation (d = 0.3-2 μm) on retention of monodisperse as well as polydisperse suspensions was studied as a function of flow velocity. Despite electrostatically unfavorable conditions, at all flow velocities, an increased retention of colloids was observed at the rough surface compared to a smooth surface without surface pattern. The impact of surface roughness on retention was found to be more significant for smaller colloids (d = 0.3, 0.43 vs. 1, 2 μm). From smooth to rough surfaces, the deposition rate of 0.3 and 0.43 μm colloids increased by a factor of ∼2.7 compared to a factor of 1.2 or 1.8 for 1 and 2 μm colloids, respectively. For a substrate herein, with constant surface topography, the ratio between substrate roughness and radius of colloid, Rq/rc, determined the deposition efficiency. As Rq/rc increased, particle-substrate overall DLVO interaction energy decreased. Larger colloids (1 and 2 μm) beyond a critical velocity (7 × 10(-5) and 3 × 10(-6) m/s) (when drag force exceeds adhesion force) tend to detach from the surface

  19. Clinical Comparisons of Two Free Light Chain Assays to Immunofixation Electrophoresis for Detecting Monoclonal Gammopathy

    Directory of Open Access Journals (Sweden)

    Han-Sung Kim

    2014-01-01

    Full Text Available Free light chains (FLCs are useful biomarkers for the diagnosis and monitoring of various plasma cell dyscrasias. One hundred fifty-seven samples from 120 patients for screening or monitoring of monoclonal gammopathy (MG were included. The new N Latex FLC assays (Siemens Healthcare Diagnostics GmbH, Germany were compared with the Freelite FLC assays (The Binding Site Ltd., UK and the results were analyzed with those of immunofixation electrophoresis (IFE. The Freelite FLC assay showed significantly wider assay ranges than the N Latex FLC assay. The correlation coefficients of the two FLC kappa (κ assays, lambda (λ assays, and the κ/λ ratio were 0.9792, 0.8264, and 0.9064, respectively. The concordance rate was 84.7% for the FLC κ assays, 79.6% for FLC λ, and 89.2% for the κ/λ ratio. The clinical sensitivity and specificity of the κ/λ ratios were 72.2% and 93.6% for the Freelite assay and 64.6% and 100% for the N Latex FLC assay. Two FLC assays showed good correlations and concordance. However, the clinical sensitivity of the κ/λ ratio was higher in the Freelite FLC assays; clinical specificity was higher in the N Latex FLC assay. Both FLC assays seem to have limited clinical utility in detecting MG in certain clinical settings.

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

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Ahmad Fikri Abdul, E-mail: a.fikri-89@yahoo.com; Ariff, Zulkifli Mohamad [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Ismail, Hanafi [Cluster for Polymer Composites (CPC), Science and Engineering Research Centre, Engineering Campus, Universiti Sains Malaysia,14300 Nibong Tebal, Pulau Pinang (Malaysia)

    2015-07-22

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

  1. The evolution and use of a personal LaTeX metapackage

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    This document defines and describes esameta.sty and its variant esametaps.sty. They are personal LATEX packages that largely consist of calls of other packages. These 'metapackages' are selected to help the development of the author's complex book and paper projects-but some of his decisions might...... be of more general relevance. The use of the LATEX system of 'literate programming' and the testing the compatibility of new commands and packages with the previously included parts of the metapackage should also be noticed....

  2. Trial Production of Surgical Gloves from Irradiated Natural Rubber Latex on Factory Scale

    Directory of Open Access Journals (Sweden)

    M. Utama

    2005-07-01

    Full Text Available Trial production of surgical gloves from irradiated natural rubber latex at the PT. Laxindo Utama Serang Banten glove factory has been carried out. The variation of heating temperature and leaching time during processing were evaluated. The physical and mechanical properties and the protein allergen respond of surgical gloves using ELISA method were measured. The results showed that the physical and mechanical of surgical gloves such as tensile strength, modulus, and elongation at break arefound to meet the requirements of the ISO or SNI standard for surgical gloves. While the allergic response through clinical tested latex-sensitive protein allergen known as ELISA test is found to be negative.

  3. 求解农产品供应链网络设计问题的混合粒子群算法%Hybrid Particle Swarm Algorithms for Solving Design Problems of Agri-food Supply Chain Network

    Institute of Scientific and Technical Information of China (English)

    赵霞; 窦建平

    2013-01-01

    为求解以混合整数规划(MIP)模型表征的农产品供应链网络(Agri-food Supply Chain Network,ASCN)优化设计问题,提出了基于混合粒子群算法(Particle Swarm Algorithm,PSA)的优化方法.分别将单邻域搜索和简化变邻域搜索作为局部搜索技术嵌入PSA中构建了两种混合PSAs.由混合PSA搜索MIP中二元决策变量,随后由LINGO求解MIP导出的线性规划问题并获取解.以陕西苹果产业集群的ASCN设计及其修改案例为例,验证了基于混合PSA优化方法的有效性.案例计算结果对比表明,增加局部搜索可显著增强PSA全局寻优能力,且简化变邻域搜索在改善PSA全局搜索能力上优于单邻域搜索.

  4. DMS AND 13C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVA c/PBA

    Institute of Scientific and Technical Information of China (English)

    YAN Xin; XU Xiaolong; ZHANG Baozhen; YAO Shuren; QIAN Baogong

    1993-01-01

    The compatibility and dynamics of latex bidirectional interpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the 13C linewidths of PBA and temperature is also discussed.

  5. Plasma etched surface scanning inspection recipe creation based on bidirectional reflectance distribution function and polystyrene latex spheres

    Science.gov (United States)

    Saldana, Tiffany; McGarvey, Steve; Ayres, Steve

    2014-04-01

    The continual increasing demands upon Plasma Etching systems to self-clean and continue Plasma Etching with minimal downtime allows for the examination of SiCN, SiO2 and SiN defectivity based upon Surface Scanning Inspection Systems (SSIS) wafer scan results. Historically all Surface Scanning Inspection System wafer scanning recipes have been based upon Polystyrene Spheres wafer deposition for each film stack and the subsequent creation of light scattering sizing response curves. This paper explores the feasibility of the elimination of Polystyrene Latex Sphere (PSL) and/or process particle deposition on both filmed and bare Silicon wafers prior to Surface Scanning Inspection System recipe creation. The study will explore the theoretical maximal Surface Scanning Inspection System sensitivity based on PSL recipe creation in conjunction with the maximal sensitivity derived from Bidirectional Reflectance Distribution Function (BRDF) maximal sensitivity modeling recipe creation. The surface roughness (Root Mean Square) of plasma etched wafers varies dependent upon the process film stack. Decrease of the root mean square value of the wafer sample surface equates to higher surface scanning inspection system sensitivity. Maximal sensitivity SSIS scan results from bare and filmed wafers inspected with recipes created based upon Polystyrene/Particle Deposition and recipes created based upon BRDF modeling will be overlaid against each other to determine maximal sensitivity and capture rate for each type of recipe that was created with differing recipe creation modes. A statistically valid sample of defects from each Surface Scanning Inspection system recipe creation mode and each bare wafer/filmed substrate will be reviewed post SSIS System processing on a Defect Review Scanning Electron Microscope (DRSEM). Native defects, Polystyrene Latex Spheres will be collected from each statistically valid defect bin category/size. The data collected from the DRSEM will be utilized to

  6. Nodal-chain metals

    Science.gov (United States)

    Bzdušek, Tomáš; Wu, Quansheng; Rüegg, Andreas; Sigrist, Manfred; Soluyanov, Alexey A.

    2016-10-01

    The band theory of solids is arguably the most successful theory of condensed-matter physics, providing a description of the electronic energy levels in various materials. Electronic wavefunctions obtained from the band theory enable a topological characterization of metals for which the electronic spectrum may host robust, topologically protected, fermionic quasiparticles. Many of these quasiparticles are analogues of the elementary particles of the Standard Model, but others do not have a counterpart in relativistic high-energy theories. A complete list of possible quasiparticles in solids is lacking, even in the non-interacting case. Here we describe the possible existence of a hitherto unrecognized type of fermionic excitation in metals. This excitation forms a nodal chain—a chain of connected loops in momentum space—along which conduction and valence bands touch. We prove that the nodal chain is topologically distinct from previously reported excitations. We discuss the symmetry requirements for the appearance of this excitation and predict that it is realized in an existing material, iridium tetrafluoride (IrF4), as well as in other compounds of this class of materials. Using IrF4 as an example, we provide a discussion of the topological surface states associated with the nodal chain. We argue that the presence of the nodal-chain fermions will result in anomalous magnetotransport properties, distinct from those of materials exhibiting previously known excitations.

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

    Science.gov (United States)

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

    2016-01-01

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

  8. Secretory Duct Structure and Phytochemistry Compounds of Yellow Latex in Mangosteen Fruit

    Directory of Open Access Journals (Sweden)

    DORLY

    2008-09-01

    Full Text Available Yellow latex is the main problem in mangosteen agribusiness, because it is one factor lowering the fruit quality. The structure of yellow latex secretory ducts in the flower and fruit as well as in the root, stem and leaf of mangosteen (Garcinia mangostana L. seedling and the qualitative phytochemistry of yellow latex were studied. The ducts were branched, canal-like type. They were found in the exocarp, mesocarp, endocarp, aril of the fruit, flower, stem, and leaf. In the fruit, the biggest diameter of the secretory ducts was found in the endocarp. There were continuous secretory ducts from fruit stalk to the fruit. Ultrastructural observation showed that the ducts surrounded by specific epithelial cells, which were living cells containing dense cytoplasm with plastid, mitochondria and golgi apparatus organelles. The qualitative test indicated that the yellow latex collected from stem bark, outer part of fruit, young fruit pericarp, mature aril and young aril contained terpenoid, flavonoid and tannin, but not alkaloid, saponin and steroid, except in the young aril containing the steroid.

  9. [The latex agglutination with video digital registration: the enhancement of diagnostic significance of conventional technique].

    Science.gov (United States)

    Starovoĭtova, T A; Steriopolo, N A; Zaĭko, V V; Vengerov, Iu Iu

    2012-02-01

    The rapid semiquantitative latex-tests, because of their analytic characteristics and convenient application, became widespread in the practice of laboratory diagnostics. Though, in spite of high sensitivity and specificity, their diagnostic effectiveness is lower that it could be mainly because of the impossibility to document the results of latex agglutinative re4actions and to manage the objective quality control. The application of systems of video digital registration permits to enhance the clinical significance of these analyses. By means of scanner systems (control and program complex "Expert Lab") the image of analytic objects is received with the results of latex agglutination reaction. The application of program techniques (the programs "Expert Lab - Agglutination" and "Expert Lab - Agglutination - Micros") in data processing permits to get the precise qualitative characteristics of active reactions, to ensure the automatic interpretation of results and gives an opportunity to proceed with the internal laboratory quality control. The saving of analytic object image in computer memory after termination of reaction favors the formation of data base, the implementation of retrospective evaluation of obtained results, additional consultations in dubious cases, including on-line. The application of complex "Expert Lab" permitted to develop the miniaturizes matrix systems permitting to decrease the withdrawal of latex reagents, to increase the productivity of analytical stage of operation preserving all analytical characteristics of method.

  10. Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME)

    NARCIS (Netherlands)

    Benhabib, K.; Town, R.M.; Leeuwen, van H.P.

    2009-01-01

    Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the co

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

    Directory of Open Access Journals (Sweden)

    Thiago Lustosa Jucá

    2013-01-01

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

  12. Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

    NARCIS (Netherlands)

    Raja, T.N.; Brouwer, A.M.; Biemans, K.; Nabuurs, T.; Tennebroek, R.

    2010-01-01

    In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe 1 was copolymerized via emulsion polymerization. The presence of organic co-solvents insid

  13. Permeability of nitrile rubber, latex, polyurethane, and neoprene gloves to 18 antineoplastic drugs.

    Science.gov (United States)

    Connor, T H

    1999-12-01

    The permeability of four glove materials to various antineoplastic drugs was studied. Eighteen antineoplastic drugs posing potential health hazards to handlers were prepared at the highest concentrations normally encountered by hospital personnel. Four glove materials-nitrile rubber, latex, polyurethane, and neoprene-were exposed to the drugs for 30, 60, 90, and 120 minutes. Glove thickness was measured with an electronic digital caliper. Random samples of material were selected from the glove fingertips, and triplicate samples were tested for each drug at each interval. For a majority of the drugs, a bacterial mutagenicity assay was used to measure the amount of drug (if any) that permeated the material. High-performance liquid chromatography was used for drugs not tested with the bacterial assay. The nitrile gloves were the thinnest (0.12 mm), and the latex gloves were the thickest (0.18 mm). The four materials were generally impermeable to each drug. One sample of the nitrile gloves appeared to have a defect, allowing >5% of the drug solution to pass through at 30 minutes. One sample each of the latex, polyurethane, and neoprene gloves demonstrated minimal permeability (neoprene materials. Nitrile rubber, latex, polyurethane, and neoprene gloves were impermeable to 18 antineoplastic drugs in most, but not all, cases.

  14. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    Energy Technology Data Exchange (ETDEWEB)

    Keong, C C; Zin, W M Wan; Ibrahim, P; Ibrahim, S, E-mail: chai@nuclearmalaysia.gov.my [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2010-05-15

    Radiation prevulcanized natural rubber latex (RVNRL) was claimed to be more user friendly than natural rubber latex prevulcanized by sulphur curing system. The absence of Type IV allergy inducing chemicals in RVNRL make it a suitable material for manufacturing of many kinds of latex products, especially those come into direct contact with users. This paper reveals and discusses the findings of cytotoxicity test and safety evaluation on animal for RVNRL. The test was done on RVNRL films prepared by coagulant dipping method and RVNRL dipped products produced by latex dipped product manufacturers. Cytotocixity test was carried out on mammalian cell culture American Type Culture Collection CCL 81, Vero. Results indicated that no cytotoxic effect from RVNRL films and products was found on the cell culture. Two animal studies, namely dermal sensitization study and primary skin irritation study, were done on gloves made from RVNRL. Albino white guinea pigs were used as test subjects in dermal sensitization study and results showed no sensitization induced by the application of test material in the guinea pigs. Primary skin irritation study was done on New Zealand white rabbits and results showed that the product tested was not corrosive and was not a primary irritant

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

    Science.gov (United States)

    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...

  16. Ethnobotanical study of latex plants in the maritime Region of Togo

    Directory of Open Access Journals (Sweden)

    Yao Patrick Hoekou

    2016-01-01

    Full Text Available Background: In Togo, a little is known about latex plants of the flora used for medicinal purposes. Objective: The aim of this study was to identify the latex plant species and their medicinal uses in the Maritime Region of Togo. Materials and Methods: The methodology was based on ethnobotanical semi-structural individual interviews of 220 informants. Quantitative ethnobotanical index was used to analyze the data. Results: A total of 33 latex plants species were recorded, from 12 botanical families and 24 genera. The most represented families were Euphorbiaceae and Moraceae with eight species each. The relative importance (RI value of each species and the informant consensus factor (ICF of the ailments categories showed that Pergularia daemia (Forssk. Chiov. (RI = 2.00 and Euphorbia hirta L. (RI = 1.91 were the most versatile in relation to their uses, and infectious diseases (ICF = 0.922 were the category with the greatest consensus among 17 categories. Conclusion: These latex plants of Togolese flora are variously used in traditional medicine and it would be important to undertake further investigations in phytochemistry, pharmacology, and toxicology to validate their uses.

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

    Directory of Open Access Journals (Sweden)

    Pedro Marcos de Almeida

    2015-03-01

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

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

    Science.gov (United States)

    Sullivan, Eric; Melvin, Timothy

    2016-01-01

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

  19. Formation of Defect-Free Latex Films on Porous Fiber Supports

    KAUST Repository

    Lively, Ryan P.

    2011-09-28

    We present here the creation of a defect-free polyvinylidene chloride barrier layer on the lumen-side of a hollow fiber sorbent. Hollow fiber sorbents have previously been shown to be promising materials for enabling low-cost CO 2 capture, provided a defect-free lumen-side barrier layer can be created. Film experiments examined the effect of drying rate, latex age, substrate porosity (porous vs nonporous), and substrate hydrophobicity/ hydrophilicity. Film studies show that in ideal conditions (i.e., slow drying, fresh latex, and smooth nonporous substrate), a defect-free film can be formed, whereas the other permutations of the variables investigated led to defective films. These results were extended to hollow fiber sorbents, and despite using fresh latex and relatively slow drying conditions, a defective lumen-side layer resulted. XRD and DSC indicate that polyvinylidene chloride latex develops crystallinity over time, thereby inhibiting proper film formation as confirmed by SEM and gas permeation. This and other key additional challenges associated with the porous hollow fiber substrate vs the nonporous flat substrate were overcome. By employing a toluene-vapor saturated drying gas (a swelling solvent for polyvinylidene chloride) a defect-free lumen-side barrier layer was created, as investigated by gas and water vapor permeation. © 2011 American Chemical Society.

  20. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    Science.gov (United States)

    Keong, C. C.; Zin, W. M. Wan; Ibrahim, P.; Ibrahim, S.

    2010-05-01

    Radiation prevulcanized natural rubber latex (RVNRL) was claimed to be more user friendly than natural rubber latex prevulcanized by sulphur curing system. The absence of Type IV allergy inducing chemicals in RVNRL make it a suitable material for manufacturing of many kinds of latex products, especially those come into direct contact with users. This paper reveals and discusses the findings of cytotoxicity test and safety evaluation on animal for RVNRL. The test was done on RVNRL films prepared by coagulant dipping method and RVNRL dipped products produced by latex dipped product manufacturers. Cytotocixity test was carried out on mammalian cell culture American Type Culture Collection CCL 81, Vero. Results indicated that no cytotoxic effect from RVNRL films and products was found on the cell culture. Two animal studies, namely dermal sensitization study and primary skin irritation study, were done on gloves made from RVNRL. Albino white guinea pigs were used as test subjects in dermal sensitization study and results showed no sensitization induced by the application of test material in the guinea pigs. Primary skin irritation study was done on New Zealand white rabbits and results showed that the product tested was not corrosive and was not a primary irritant

  1. Genome Sequence of Phytomonas françai, a Cassava (Manihot esculenta) Latex Parasite

    Science.gov (United States)

    Butler, Claire E.; Jaskowska, Eleanor

    2017-01-01

    ABSTRACT Here, we report the genome sequence of the cassava (Manihot esculenta) latex parasite Phytomonas françai. P. françai infection is linked with the yield-loss disease “chochamento de raizes” (empty roots) in the Unha variety of cassava, a disease characterized by poor root development and chlorosis of the leaves. PMID:28082482

  2. Stokes and anti-stokes stimulated Mie scattering on nanoparticle suspensions of latex

    Science.gov (United States)

    Burkhanov, I. S.; Krivokhizha, S. V.; Chaikov, L. L.

    2016-12-01

    Stokes and anti-Stokes shifts of stimulated concentration light scattering (SCLS, stimulated Mie scattering) in suspensions of various-sized latex nanoparticles in water were measured by the light guide scheme, under conditions of backscattering in the presence of convection.

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2016-04-15

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

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

    Science.gov (United States)

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

  6. The inflammatory stimulus of a natural latex biomembrane improves healing in mice

    NARCIS (Netherlands)

    Andrade, T.A.M.; Iyer, A.; Das, P.K.; Foss, N.T.; Garcia, S.B.; Coutinho-Netto, J.; Jordão-Jr., A.A.; Frade, M.A.C.

    2011-01-01

    The aim of the present study was to compare healing obtained with biomembranes with the natural healing process (sham) using biochemical and immunohistological assays. C57BL/6 mice were divided into 4 groups of 15 mice each and received different subcutaneous implants: natural latex biomembrane (NLB

  7. Lobelia siphilitica plants that escape herbivory in time also have reduced latex production.

    Directory of Open Access Journals (Sweden)

    Amy L Parachnowitsch

    Full Text Available Flowering phenology is an important determinant of a plant's reproductive success. Both assortative mating and niche construction can result in the evolution of correlations between phenology and other reproductive, functional, and life history traits. Correlations between phenology and herbivore defence traits are particularly likely because the timing of flowering can allow a plant to escape herbivory. To test whether herbivore escape and defence are correlated, we estimated phenotypic and genetic correlations between flowering phenology and latex production in greenhouse-grown Lobelia siphilitica L. (Lobeliaceae. Lobelia siphilitica plants that flower later escape herbivory by a specialist pre-dispersal seed predator, and thus should invest fewer resources in defence. Consistent with this prediction, we found that later flowering was phenotypically and genetically correlated with reduced latex production. To test whether herbivore escape and latex production were costly, we also measured four fitness correlates. Flowering phenology was negatively genetically correlated with three out of four fitness estimates, suggesting that herbivore escape can be costly. In contrast, we did not find evidence for costs of latex production. Generally, our results suggest that herbivore escape and defence traits will not evolve independently in L. siphilitica.

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

    Directory of Open Access Journals (Sweden)

    Anuar Magaña-Álvarez

    2016-04-01

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

  9. Crystallization of Hevamine, an Enzyme with Lysozyme/Chitinase Activity from Hevea brasiliensis Latex

    NARCIS (Netherlands)

    ROZEBOOM, HJ; BUDIANI, A; BEINTEMA, JJ

    1990-01-01

    Hevamine, an enzyme with both lysozyme and chitinase activity, was isolated and purified from Hevea brasiliensis (rubber tree) latex. The enzyme (molecular weight 29,000) is homologous to certain “pathogenesis-related” proteins from plants, but not to hen egg-white or phage T4 lysozyme. To investiga

  10. Concentration of field and skim latex by microfiltration - membrane fouling and biochemical methane potential of serum.

    Science.gov (United States)

    Thongmak, Narumol; Sridang, Porntip; Puetpaiboon, Udomphon; Grasmick, Alain

    2015-01-01

    Cross-flow microfiltration was used to concentrate field and skim latex suspensions and recover the smallest compounds (proteins, sugars, etc.) in permeate (serum solutions). The experiments were performed in a lab-scale microfiltration unit equipped with ceramic membranes. In continuous mode, the operations were performed at constant trans-membrane pressure (0.5 bars), constant cross-flow velocity (3 m/s) and constant temperature (28 ± 2°C). In retentate, the volumetric concentration factor was only close to 2 (about 54% of total solid content, TSC) when concentrating the field latex suspensions, and it reached 10 (close to 40% TSC) when concentrating skim latex suspensions. The quality of retentate suspensions let envisage a significant potential of industrial valorization. The membrane fouling rates appeared as an increasing function of dry rubber content suspension, and the main fouling origin (94%) was linked to a reversible accumulation of suspended compounds on the membrane surface. Permeate appeared as a clear yellow solution containing the smallest soluble organic fractions that show a high degree of biodegradability when using biochemical methane potential tests. The chemical oxygen demand (COD) removal was then higher than 92% and the methane production yield was close to 0.29 NLCH4/gCODremoved. The association of a membrane separation step and anaerobic digestion appeared, then, as a relevant solution to recover rubber content from skim latex suspensions and energy from the anaerobic digestion of serum.

  11. Decrease in the rate of sensitization and clinical allergy to natural rubber latex

    DEFF Research Database (Denmark)

    Blaabjerg, Michelle S B; Andersen, Klaus E; Bindslev-Jensen, Carsten

    2015-01-01

    BACKGROUND: In the 1980s, a striking increase in natural rubber latex (NRL) allergy was seen. Since then, many measures have been taken to prevent NRL allergy. OBJECTIVES: To investigate changes in the prevalence of NRL sensitization/clinical NRL allergy over time from 2002 to 2013. METHODS: All...

  12. Heat transport in coupled inhomogeneous chains

    Institute of Scientific and Technical Information of China (English)

    Hu Tao; Bai Meng; Hu Ke; Tang Yi

    2011-01-01

    We first investigate the heat transport in a network model consisting of two coupled dimerized chains. Results indicate that the thermal resistance of each chain increases with the decrease of the mass ratio γ of the two types of atoms. Then, we find, when a light impurity or a heavy one is added in the two coupled homogeneous chains and coupled with a particle of another chain, the interface thermal resistances Rlint andRγint present different dependences on the mass ratio γ'. Finally, a persistent circulation of energy current is observed in coupled inhomogeneous chains with two pairs of interchain coupling.

  13. Label-free quantitative proteomics reveals differentially regulated proteins in the latex of sticky diseased Carica papaya L. plants.

    Science.gov (United States)

    Rodrigues, Silas P; Ventura, José A; Aguilar, Clemente; Nakayasu, Ernesto S; Choi, HyungWon; Sobreira, Tiago J P; Nohara, Lilian L; Wermelinger, Luciana S; Almeida, Igor C; Zingali, Russolina B; Fernandes, Patricia M B

    2012-06-18

    Papaya meleira virus (PMeV) is so far the only described laticifer-infecting virus, the causal agent of papaya (Carica papaya L.) sticky disease. The effects of PMeV on the laticifers' regulatory network were addressed here through the proteomic analysis of papaya latex. Using both 1-DE- and 1D-LC-ESI-MS/MS, 160 unique papaya latex proteins were identified, representing 122 new proteins in the latex of this plant. Quantitative analysis by normalized spectral counting revealed 10 down-regulated proteins in the latex of diseased plants, 9 cysteine proteases (chymopapain) and 1 latex serine proteinase inhibitor. A repression of papaya latex proteolytic activity during PMeV infection was hypothesized. This was further confirmed by enzymatic assays that showed a reduction of cysteine-protease-associated proteolytic activity in the diseased papaya latex. These findings are discussed in the context of plant responses against pathogens and may greatly contribute to understand the roles of laticifers in plant stress responses.

  14. Luminescence techniques and characterization of the morphology of polymer latices. 3. An investigation of the microenvironments within stabilized aqueous latex dispersions of poly(n-butyl methacrylate) and polyurethane.

    Science.gov (United States)

    Soutar, I; Swanson, L; Annable, T; Padget, J C; Satgurunathan, R

    2006-06-20

    Fluorescence techniques (including time-resolved anisotropy measurements, TRAMS) have been used to probe differences in morphology between two stabilized aqueous latex dispersions (poly(n-butyl methacrylate), PBMA, and polyurethane, PU). Use of the emission characteristics of probes such as pyrene and phenanthrene dispersed within particles reveals that the PU latices are more heterogeneous in nature: evidence exists, particularly from quenching measurements and TRAMS, that voids and channels of water permeate the PU structure, resulting in a relatively soft, open particle, swollen by ingress of the bulk aqueous phase. Fluorescence measurements indicate that PBMA colloids, however, are composed of relatively hard, hydrophobic particles. In addition, TRAMS are considered to be a valuable tool both for probing the morphological characteristics of such dispersions and in estimating the average particle size.

  15. Preparation of Organic Phosphate Modified Styrene-Acrylate Grafted Epoxy Resins Latex and Its Anti-Corrosion Property%磷酸酯改性苯丙接枝环氧树脂胶乳的制备及其防腐蚀性能

    Institute of Scientific and Technical Information of China (English)

    毛正和; 钟涛; 朱爱萍; 夏中高; 杨芳芳

    2012-01-01

    采用乳液聚合方法制备了一种用于水性金属防腐蚀涂料的磷酸酯改性苯丙接枝环氧树脂胶乳,其中环氧树脂占胶乳固体含量30%,磷酸酯占胶乳固体含量1.2%.制备的胶乳可室温交联固化.采用透射电镜表征了胶乳的形貌,红外光谱表征胶乳的结构,偏光显微镜研究金属的闪锈行为,拉开法测定附着力.结果表明:胶乳粒子呈现规则的球型形貌,粒径为130 ~ 150 nm,粒径分布均匀;磷酸酯以共价键的方式连接在苯丙接枝环氧树脂胶乳中;胶乳具有优异的防闪锈性,干/湿附着力优异,同时乳胶膜具有优异的机械力学性能、耐盐水性能以及防腐蚀性能.%Emulsion polymerization was used to prepare the organic phosphate modified styrene — acrylate grafted epoxy resins latex for preparation of the waterborne metal anticorrosive coatings, in which epoxy resin content was 30% and organic phosphate content was 1.2%. The resulting latex could be crosslinked at room temperature. The latex morphology was characterized with TEM; the structure was measured with FT - IR; the flash rust behaviors on metals were studied with the polarizing microscope; and the adhesion was measured with the pull - off method. The results indicated that the latex particles showed regular spheroidal morphology, with 130-150 nm in diameter and uniform particle size distribution; the organic phosphate linked with styrene - acrylate grafted epoxy resins latex by covalent bond; the latex was excellent in flash rust resistance and drying/wet adhesion. And the latex film could provide good mechanical properties, salt water resistance and anti - corrosion property.

  16. STUDY ON THE FORMATION MECHANISM OF MONODISPERSE PARTICLES IN THE EMULSIFIER-FREE EMULSION POLYMERIZATION OF METHYL METHACRYLATE AND BUTYL ACRYLATE

    Institute of Scientific and Technical Information of China (English)

    Hong-quan Xie; Gui-ying Liao; Yu Gao

    2003-01-01

    The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerization of methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formation mechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be the coagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with high surface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formed by the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization system and then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leads to the aggregation of the growing particles and the formation of larger latex particles therefrom. After the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards a uniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D43/D10) in the first stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation of the monodisperse particles.

  17. Mercury sensing and toxicity studies of novel latex fabricated silver nanoparticles.

    Science.gov (United States)

    Borase, Hemant P; Patil, Chandrashekhar D; Salunkhe, Rahul B; Suryawanshi, Rahul K; Salunke, Bipinchandra K; Patil, Satish V

    2014-11-01

    Safe and eco-friendly alternatives to currently used hazardous chemico-physical methods of silver nanoparticles (AgNPs) synthesis are need of time. Rapid, low cost, selective detection of toxic metals in environmental sample is important to take safety action. Toxicity assessment of engineered AgNPs is essential to avoid its side effects on human and non-target organisms. In the present study, biologically active latex from Euphorbia heterophylla (Poinsettia) was utilized for synthesis of AgNPs. AgNPs was of spherical shape and narrow size range (20-50 nm). Occurrence of elemental silver and crystalline nature of AgNPs was analyzed. Role of latex metabolites in reduction and stabilization of AgNPs was analyzed by FT-IR, protein coagulation test and phytochemical analysis. Latex-synthesized AgNPs showed potential in selective and sensitive detection of toxic mercury ions (Hg(2+)) with limit of detection around 100 ppb. Addition of Hg(2+) showed marked deviation in color and surface plasmon resonance spectra of AgNPs. Toxicity studies on aquatic non-target species Daphnia magna showed that latex-synthesized AgNPs (20.66 ± 1.52% immobilization) were comparatively very less toxic than chemically synthesized AgNPs (51.66 ± 1.52% immobilization). Similarly, comparative toxicity study on human red blood cells showed lower hemolysis (4.46 ± 0.01%) by latex-synthesized AgNPs as compared to chemically synthesized AgNPs causing 6.14 ± 0.01% hemolysis.

  18. Isolation and partial characterization of a D-galactose-binding lectin from the latex of Synadenium carinatum

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Souza

    2005-09-01

    Full Text Available A lectin from the latex of Synadenium carinatum was purified by affinity chromatography on immobilized-D-galactose-agarose and shown to be a potent agglutinin of human erythrocytes. The haemagglutination of human red cells was inhibited by 3.0 mM N-acetyl-D-galactopyranoside, 6.3 mM methyl-beta-D-galactopyranoside, 50 mM methyl-alpha-D-galactopyranoside and 50 mM D-fucose but not by L-fucose, demonstrating an anomeric and a conformational specificity. According to SDS-PAGE analysis, the lectin appeared to be a glycoprotein composed of two polypeptide chains of ca. 28 and 30 kDa, but size exclusion chromatography (Sephadex G-100 and native PAGE revealed a protein of apparent molecular weight 120 - 130 kDa made up of 28 and 30 kDa subunits. The lectin was stable in the range pH 6 - 9, and 4 - 56ºC. The N-terminal sequence of the 30 kDa subunit contained the conserved consensus sequence GPN observed in other D-galactose-binding lectins found in latex of members of the Euphorbiaceae.No presente trabalho, foi purificada por cromatografia de afinidade em D-galactose imobilizada em agarose, uma lectina do latex de Synadenium carinatum (ScLL. Essa lectina é uma potente aglutinina para eritrócitos humanos, cuja atividade hemaglutinante foi inibida com 3,0 mM de N acetil-D-galactopiranosidio, 6,3 mM de metil-beta-D-galactopiranosidio ou 50 mM metil-alfa-D-pironosidio ou D-fucose, porém, nenhuma inibição foi evidenciada por L-fucose, revelando uma especificidade anomérica e conformacional da lectina. A análise por SDS-PAGE dessa lectina pareceu ser uma glicoproteína composta por duas cadeias polipeptídicas de aproximadamente 28 e 30 kDa, porém, em cromatografia de exclusão por tamanho sobre Sephadex G100 e em gel nativo apresentou um peso molecular aparente de 120-130 kDa, a qual mostrou ser composta de uma mistura de subunidades de peptídeos de 28 e 30 kDa. Essa lectina manteve-se estável em pH de 6 a 9 e temperatura de 4 a 56ºC. A seq

  19. Fabrication of grating-like polystyrene latex monolayer structure as three-dimensional calibration standards for scanning probe microscope

    Institute of Scientific and Technical Information of China (English)

    Zhu Guo-Dong; Zeng Zhi-Gang; Guo Zhang; Du Qiang-Guo; Yan Xue-Jian

    2009-01-01

    This paper illuminates the preparation of grating-like polystyrene latex monolayer structure, which can minimize the effects of the size deviation of spheres and the defect transfer on the accuracy as calibration samples for micro-scopes. The latex films are grown on freshly cleaved mica substrates by vertical deposition method. The concentration dependence of the structure and the topography of latex films is characterized by optical microscope, ultraviolet-visible transmission spectrum and scanning probe microscope. The origination of such a grating-like structure is also discussed.

  20. EFFECT of blend ratio and compatibilizer on solution casted treated waste natural rubber latex/polystyrene blends

    Directory of Open Access Journals (Sweden)

    Orathai Boondamnoen

    2013-10-01

    Full Text Available Natural rubber latex waste (WL was treated with natural rubber latex (NRL prior to blend with polystyrene. Differentblend compositions of treated waste natural rubber latex (TWL and PS were carried out through solution blending. Tensileand tear properties were investigated. The compatibility improvement of the 70/30 TWL/PS blends was further investigatedusing styrene butadiene rubber (SBR and styrene graft natural rubber (SNR as compatibilizer. The mechanical properties forTWL/PS blends were improved at 15 phr of SNR.

  1. Luminescence and antibacterial studies of silver nanoparticles using the esterases-containing latex of E. Tirucalli plant via green route

    Science.gov (United States)

    Sudheerkumar, K. H.; Dhananjaya, N.; Reddy Yadav, L. S.

    2016-04-01

    Silver nanoparticles (Ag NPs) synthesized from silver nitrate solutions using the esterase-containing latex of the E. Tirucalli plant widely found in a large region in Karnataka, India. Plant-mediated synthesis of nanoparticles is a green chemistry approach that intercom-nects nanotechnology and plant biotechnology. The effect of extract concentration, contact time, and temperature on the reaction rate and the shape of the Ag nanoparticles was investigated. The nanoparticles have been characterized by powder X-ray diffraction, UV-visible spectroscopy, photoluminescence spectroscopy and morphology by scanning electron microscope, transmission electron microscopy, as a function of the ratio of silver ions to reducing agent molecules. Powder X-ray diffraction patterns show that the crystal structure obtained is face-centered cubic (fcc). The morphology of the silver nanoparticle was uniform with well-distributed elliptical particles with a range from 15 to 25nm. Ag NPs exhibit significant antibacterial activity against Bacillus cereus using the agar well diffusion method.

  2. Larvicidal activity of silver nanoparticles synthesized using Pergularia daemia plant latex against Aedes aegypti and Anopheles stephensi and nontarget fish Poecillia reticulata.

    Science.gov (United States)

    Patil, Chandrashekhar D; Borase, Hemant P; Patil, Satish V; Salunkhe, Rahul B; Salunke, Bipinchandra K

    2012-08-01

    In present study, the bioactivity of latex-producing plant Pergularia daemia as well as synthesized silver nanoparticles (AgNPs) against the larval instars of Aedes aegypti and Anopheles stephensi mosquito larvae was determined. The range of concentrations of plant latex (1,000, 500, 250, 125, 62.25, and 31.25 ppm) and AgNPs (10, 5, 2.5, 1.25, 0.625, and 0.3125 ppm) were prepared. The LC(50) and LC(90) values for first, second, third, and fourth instars of synthesized AgNPs-treated first, second, third, and fourth instars of A. aegypti (LC(50) = 4.39, 5.12, 5.66, 6.18; LC(90) = 9.90, 11.13, 12.40, 12.95 ppm) and A. stephensi (LC(50) = 4.41, 5.35, 5.91, 6.47; LC(90) = 10.10, 12.04, 13.05, 14.08 ppm) were found many fold lower than crude latex-treated A. aegypti (LC(50) = 55.13, 58.81, 75.66, 94.31; LC(90) = 113.00, 118.25, 156.95, 175.71 ppm) and A. stephensi (LC(50) = 81.47, 92.09, 96.07, 101.31; LC(90) = 159.51, 175.97, 180.67, 190.42 ppm). The AgNPs did not exhibit any noticeable effects on Poecillia reticulata after either 24 or 48 h of exposure at their LC(50) and LC(90) values against fourth-instar larvae of A. aegypti and A. stephensi. The UV-visible analysis shows absorbance for AgNPs at 520 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 44 to 255 nm with average size of 123.50 nm. AgNPs were clearly negatively charged (zeta potential -27.4 mV). This is the first report on mosquito larvicidal activity P. daemia-synthesized AgNPs.

  3. Particle Pollution

    Science.gov (United States)

    ... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

  4. First record of the behavior of latex drainage by Trigona spinipes (Fabricius (Hymenoptera, Apidae in laticiferous flowers

    Directory of Open Access Journals (Sweden)

    Cristiana Koschnitzke

    2011-09-01

    Full Text Available This paper describes the behavior of the bee Trigona spinipes, to avoid the latex, when piercing the base of the tubular corolla of the flowers of Mandevilla guanabarica in order to steal the nectar.

  5. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    Science.gov (United States)

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping.

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

    Science.gov (United States)

    Greenbury, C L; Keningale, J

    1960-07-01

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

  7. Evaluation of a latex agglutination assay for the identification of Burkholderia pseudomallei and Burkholderia mallei.

    Science.gov (United States)

    Duval, Brea D; Elrod, Mindy G; Gee, Jay E; Chantratita, Narisara; Tandhavanant, Sarunporn; Limmathurotsakul, Direk; Hoffmaster, Alex R

    2014-06-01

    Cases of melioidosis and glanders are rare in the United States, but the etiologic agents of each disease (Burkholderia pseudomallei and Burkholderia mallei, respectively) are classified as Tier 1 select agents because of concerns about their potential use as bioterrorism agents. A rapid, highly sensitive, and portable assay for clinical laboratories and field use is required. Our laboratory has further evaluated a latex agglutination assay for its ability to identify B. pseudomallei and B. mallei isolates. This assay uses a monoclonal antibody that specifically recognizes the capsular polysaccharide produced by B. pseudomallei and B. mallei, but is absent in closely related Burkholderia species. A total of 110 B. pseudomallei and B. mallei were tested, and 36 closely related Burkholderia species. The latex agglutination assay was positive for 109 of 110 (99.1% sensitivity) B. pseudomallei and B. mallei isolates tested.

  8. Proteinase activity in latex of three plants of the family Euphorbiaceae

    Directory of Open Access Journals (Sweden)

    Andréa Michel Sobottka

    2014-09-01

    Full Text Available In the family of Euphorbiaceae,the genera Euphorbia and Sapium are known to contain essentially latex-bearing species. In the present study, the latex of Euphorbia selloi(Klotzsch & Garcke Boiss., Euphorbia papillosa A.St.-Hil., and Sapium glandulosum (L. Morong, plants native from Brazil, were examined concerning proteolytic activity. All studied species have proteins with significant proteolytic activity and E. papillosa has the greatest specific activity. Aiming to verify the type of protease present, an assay with different inhibitors was performed. In the three tested plants, the proteolytic activity was significantly inhibited by a serine protease inhibitor 4-(2-aminoethyl-benzenesulfonyl fluoride hydrochloride (AEBSF. Using techniques of electrophoresis with polyacrylamide gels (SDS-PAGE, the subunits of proteins were separated according to their molecular masses, and the protein activity was visually detected by zymography.

  9. Suitability of Natural Rubber Latex and Waste Foundry Sand in Cement Concrete

    Directory of Open Access Journals (Sweden)

    Samuel Idiculla Thomas

    2016-06-01

    Full Text Available Suitability of Natural Rubber Latex (NRL as an additive and Waste Foundry Sand (WFS as partial replacement to river sand, in cement concrete was investigated. Experimental study was performed with concrete mixtures containing 1% latex to water ratio, along with 5% and 10% replacement of river sand by WFS. Properties of concrete were studied in both fresh and hardened state. The results of laboratory tests indicate that WFS and NRL reduces the workability of concrete. Slight reduction in splitting tensile strength was observed for mixtures containing NRL and WFS, in comparison to conventional mix. No specific trend was observed for flexural strength at 7 days, but at 28 days the difference was within ±3%, when compared to conventional mix. Strength development for mixtures containing NRL and WFS was slightly lower than conventional mix. The limited results of this study show that concrete containing NRL and WFS do have potential for use as non- structural concrete.

  10. texreg: Conversion of Statistical Model Output in R to LATEX and HTML Tables

    Directory of Open Access Journals (Sweden)

    Philip Leifeld

    2013-11-01

    Full Text Available A recurrent task in applied statistics is the (mostly manual preparation of model output for inclusion in LATEX, Microsoft Word, or HTML documents usually with more than one model presented in a single table along with several goodness-of-fit statistics. However, statistical models in R have diverse object structures and summary methods, which makes this process cumbersome. This article first develops a set of guidelines for converting statistical model output to LATEX and HTML tables, then assesses to what extent existing packages meet these requirements, and finally presents the texreg package as a solution that meets all of the criteria set out in the beginning. After providing various usage examples, a blueprint for writing custom model extensions is proposed.

  11. Zeta potential of mica covered by colloid particles: a streaming potential study.

    Science.gov (United States)

    Adamczyk, Zbigniew; Zaucha, Maria; Zembala, Maria

    2010-06-15

    The streaming potential of mica covered by monodisperse latex particles was measured using the parallel-plate channel, four-electrode cell. The zeta potential of latex bearing amidine charged groups was regulated by the addition of NaCl (10(-4)-10(-2) M) and MgCl(2) (10(-4)-10(-2) M) at a constant pH 5.5 and by the change in pH (4-12) at 10(-2) M NaCl. The size of the latex particles, determined by dynamic light scattering, varied between 502 and 540 nm for the above electrolyte concentration range. Mica sheets have been covered with latex particles under diffusion transport conditions. The latex coverage was regulated by the bulk suspension concentration in the channel and the deposition time. The coverage was determined, with a relative precision of 2%, by the direct enumeration of particles by optical microscopy and AFM. The streaming potential of mica was then determined for a broad range of particle coverage 0 < theta < 0.5, the particle-to-substrate zeta potential ratio zeta(p)/zeta(i), and 8.8 < kappa a < 143 (thin double-layer limit). These experimental data confirmed that the streaming potential of covered surfaces is well reflected by the theoretical approach formulated in ref 32. It was also shown experimentally that variations in the substrate streaming potential with particle coverage for theta < 0.3 and zeta(p)/zeta(i) < 0 are characterized by a large slope, which enables the precise detection of particles attached to interfaces. However, measurements at high coverage and various pH values revealed that the apparent zeta potential of covered surfaces is 1/2(1/2) smaller than the bulk zeta potential of particles (in absolute terms). This is valid for arbitrary zeta potentials of substrates and particles, including the case of negative particles on negatively charged substrates that mimics rough surfaces. Therefore, it was concluded that the streaming potential method can serve as an efficient tool for determining bulk zeta potentials of colloids and

  12. Evaluation of a new latex agglutination test for detection of streptolysin O antibodies.

    OpenAIRE

    Gerber, M. A.; Caparas, L S; Randolph, M F

    1990-01-01

    Acute- and convalescent-phase serum specimens were collected from 50 patients with group A streptococcal pharyngitis. The anti-streptolysin O (ASO) titer for each serum specimen was determined by using both the standard neutralization assay and the latex agglutination (LA) test (Rheumagen ASO; Biokit Inc., New Britain, Conn.). When the ASO titers derived by the two methods were compared, the correlation coefficient was 0.93. When the ability of the LA test to demonstrate a significant ASO tit...

  13. Characterization and optimization of sheep hydatid fluid antigen and its application in the latex test

    OpenAIRE

    Fuentes, Flor; Centro Nacional de Productos Biológicos, Instituto Nacional de Salud. Lima, Perú. Químico farmacéutico.; Incio, Nelly; Centro Nacional de Productos Biológicos, Instituto Nacional de Salud. Lima, Perú. Químico farmacéutico.; Lévano, Juan; Centro Nacional de Productos Biológicos, Instituto Nacional de Salud. Lima, Perú. Médico veterinario.; Torres, Yovanna; SAIS Tupac Amaru, EsSalud. Junín Perú. Médico.

    2009-01-01

    It was characterized and optimized sheep hydatid fluid antigen and applied in latex fixation tests as screening test for serological diagnosis of patients with Echinococcus granulosus cysts. We evaluated 40 sera, 15 sera positive by immunoblot from patients with E. granulosus infection, 10 sera from patients with other parasitic diseases and 15 sera from healthy subject. Three of the 15 hydatidosis sera were negative and 0 / 25 sera with hydatidosis were reactive. The sensitivity was 80% (95%...

  14. Toxicological study of the molluscicidal latex of Euphorbia splendens: irritant action on skin and eye

    Directory of Open Access Journals (Sweden)

    J. C. B. R. Freitas

    1991-01-01

    Full Text Available Aqueous solutions of the molluscicidal latex of Euphorbia splendens are irritant to the rabbit eye in concentrations higher than 0.35% and to the rabbit skin in concentrations higher than 0.5%. Although this irritant potential does not proclude its use as a molluscicide, special precautions are recommended for hanbdling and application of the product and the hazard of skin tumor-promoting potencial should be carefully investigated before its use for schistosomiasis vector control.

  15. Comparative study between novel self cross-linking and conventional fluorinated acrylic latex

    Institute of Scientific and Technical Information of China (English)

    Li Jun Chen

    2011-01-01

    Novel self cross-linking fluorinated acrylic latex (SCLFAL) has been successfully prepared via starved seeded semi-batch emulsion polymerization. The resultant SCLFAL is characterized by Fourier transform infrared (FTTR) spectrometry. Contact angle (CA) and glass transition temperature (Tg) of the film are investigated. Results show that CA and Tg of the film can be improved when the moderate amount of HPMA is introduced into the mixed monomers.

  16. Extraction and purification of curcain, a protease from the latex of Jatropha curcas Linn.

    Science.gov (United States)

    Nath, L K; Dutta, S K

    1991-02-01

    A proteolytic enzyme, curcain, has been extracted from the latex of Jatropha curcas Linn. The enzyme was purified by chromatography on carboxymethyl cellulose and gel filtration on Sephadex G-200. The homogeneity of protein associated with curcain was established by non-denatured polyacrylamide gel electrophoresis using a discontinuous buffer system. The molecular weight of curcain was estimated by Sephadex G-100 gel filtration using a calibration curve of standard proteins to be around 22,000 daltons.

  17. A review of the LATEX project: mesoscale to submesoscale processes in a coastal environment

    Science.gov (United States)

    Petrenko, Anne A.; Doglioli, Andrea M.; Nencioli, Francesco; Kersalé, Marion; Hu, Ziyuan; d'Ovidio, Francesco

    2017-03-01

    The main objective of the LAgrangian Transport EXperiment (LATEX) project was to study the influence of coastal mesoscale and submesoscale physical processes on circulation dynamics, cross-shelf exchanges, and biogeochemistry in the western continental shelf of the Gulf of Lion, Northwestern Mediterranean Sea. LATEX was a five-year multidisciplinary project based on the combined analysis of numerical model simulations and multi-platform field experiments. The model component included a ten-year realistic 3D numerical simulation, with a 1 km horizontal resolution over the gulf, nested in a coarser 3 km resolution model. The in situ component involved four cruises, including a large-scale multidisciplinary campaign with two research vessels in 2010. This review concentrates on the physics results of LATEX, addressing three main subjects: (1) the investigation of the mesoscale to submesoscale processes. The eddies are elliptic, baroclinic, and anticyclonic; the strong thermal and saline front is density compensated. Their generation processes are studied; (2) the development of sampling strategies for their direct observations. LATEX has implemented an adaptive strategy Lagrangian tool, with a reference software available on the web, to perform offshore campaigns in a Lagrangian framework; (3) the quantification of horizontal mixing and cross-shelf exchanges. Lateral diffusivity coefficients, calculated in various ways including a novel technique, are in the range classically encountered for their associated scales. Cross-shelf fluxes have been calculated, after retrieving the near-inertial oscillation contribution. Further perspectives are discussed, especially for the ongoing challenge of studying submesoscale features remotely and from in situ data.

  18. MORPHOLOGY EVOLUTION OF POLY(St-co-BuA)/SILICA NANOCOMPOSITE PARTICLES SYNTHESIZED BY EMULSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Hua Li; Shu-xue Zhou; Bo You; Li-min Wu

    2006-01-01

    Poly(St-co-BuA)/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-(trimethoxysilyl)propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope (TEM) and scanning electron microscope (SEM) in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.

  19. Tests for intact and collapsed magnetofossil chains

    Science.gov (United States)

    Egli, R.

    2012-04-01

    In recent years, new techniques for the detection of magnetofossils have been proposed, based on their unique first-order reversal curves (FORC) and ferromagnetic resonance (FMR) signatures. These signatures are related to the non-interacting (FORC) and strongly uniaxial anisotropy (FMR) of isolated chains of magnetic particles. However, little is known about the fate of these signatures in sediments where magnetosome chains collapsed during early diagenetic processes. Due to the impossibility of observing the particle arrangement in-situ, the structure of collapsed chains can only be inferred from TEM images of magnetic extracts and from first-principles consideration on the mechanical stability of magnetosome chains once the biological material around them is dissolved. The magnetic properties of double chains, produced by some strains of cocci, are also not known. According to these considerations, four main magnetofossil structures were taken into consideration: (1) isolated, linear chains, (2) double, half-staggered chains, where the gaps of one chain face the magnetosomes in the other chain, (3) double chains with side-to-side magnetosomes, which might result from a "jackknife" type of collapse of a single, long chain, and (4) zig-zag collapsed chains of elongated crystals, where the magnetosome long axes are perpendicular to the chain axis. The collapsed structures might be relevant in sediments where magnetofossils carry a significant part of the remanent magnetization, because chain collapse tends to cancel the original natural remanent magnetization. Detailed models for the hysteretic and anhysteretic properties of structures (1-4) have been calculated by taking realistic distributions of magnetosome size, elongation, and spacing into account, as inferred from a number of published TEM observations. Model calculations took a total of >2 years continuous running time on two computers in an effort to obtain realistic results, which are shown here for the

  20. Impedance technique for measuring dielectrophoretic collection of microbiological particles

    CERN Document Server

    Allsopp, D W E; Brown, A P; Betts, W B

    1999-01-01

    Measurement of the impedance change resulting from the collection of microbiological particles at coplanar electrodes is shown to be an effective and potentially quantitative method of detecting dielectrophoresis. Strong correlations between the frequency-dependent dielectrophoretic collection characteristics measured by impedance change and those observed using an established counting method based on image analysis have been obtained for Escherichia coli. In addition it is shown that the new electrical method can be used to sense dielectrophoretic collection of 19 nm diameter latex beads, particles too small to be resolved by conventional optical detection systems. (author)

  1. Bioseparation of papain from Carica papaya latex by precipitation of papain-poly (vinyl sulfonate) complexes.

    Science.gov (United States)

    Braia, Mauricio; Ferrero, Maximiliano; Rocha, María Victoria; Loureiro, Dana; Tubio, Gisela; Romanini, Diana

    2013-09-01

    The formation of insoluble complexes between enzymes and polyelectrolytes is a suitable technique for isolating these biomolecules from natural sources, because it is a simple and rapid technique that allows the concentration of the protein. This technique can be used in most purification protocols at the beginning of the downstream process. The aim of this investigation is to isolate papain from Carica papaya latex by precipitation of insoluble complexes between this enzyme and poly (vinyl sulfonate). The papain-poly (vinyl sulfonate) complex was insoluble at pH lower than 6, with a PVS/PAP stoichiometric ratio of 1:279. Ionic strength affected the complex formation. The presence of the polymer increased the enzymatic activity and protected the enzyme from autodegradation. The optimal conditions for the formation of insoluble papain-polyelectrolyte complex formation were applied to C. papaya latex and a high recovery was obtained (around 86%) and a purification factor around 2. This method can be applied as an isolation method of papain from C. papaya latex or as a first step in a larger purification strategy.

  2. PythonTeX: reproducible documents with LaTeX, Python, and more

    Science.gov (United States)

    Poore, Geoffrey M.

    2015-01-01

    PythonTeX is a LaTeX package that allows Python code in LaTeX documents to be executed and provides access to the output. This makes possible reproducible documents that combine results with the code required to generate them. Calculations and figures may be next to the code that created them. Since code is adjacent to its output in the document, editing may be more efficient. Since code output may be accessed programmatically in the document, copy-and-paste errors are avoided and output is always guaranteed to be in sync with the code that generated it. This paper provides an introduction to PythonTeX and an overview of major features, including performance optimizations, debugging tools, and dependency tracking. Several complete examples are presented. Finally, advanced features are summarized. Though PythonTeX was designed for Python, it may be extended to support additional languages; support for the Ruby and Julia languages is already included. PythonTeX contains a utility for converting documents into plain LaTeX, suitable for format conversion, sharing, and journal submission.

  3. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    Science.gov (United States)

    Määttänen, Anni; Ihalainen, Petri; Törngren, Björn; Rosqvist, Emil; Pesonen, Markus; Peltonen, Jouko

    2016-02-01

    Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV-vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH2)11OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal (optical and electrical) real-time monitoring of length-scale-dependent biomaterial-surface interactions.

  4. Interleukin-1beta inhibits paw oedema induced by local administration of latex of Calotropis procera extracts.

    Science.gov (United States)

    Arya, Soneera; Kumar, Vijay L

    2004-01-01

    Interleukin-1beta (IL-1beta), a pro-inflammatory cytokine, has been reported to exhibit anti-inflammatory properties in the carrageenan-induced paw oedema model. In the present study, we have evaluated the anti-inflammatory activity of IL-1beta against inflammation induced by local administration of the methanol extract of dried latex of Calotropis procera (MeDL) and compared it with that against carrageenan. The anti-inflammatory activity of standard anti-inflammatory drugs, phenylbutazone (PBZ) and dexamethasone (DEX), was also evaluated against both inflammagens. Injection of an aqueous solution of dried latex and MeDL into the sub-plantar surface of the rat paw produced intense inflammation with a peak response occurring within 2 h, while the peak inflammatory response with carrageenan was obtained at 3 h. Subcutaneous injection of IL-1beta was found to be more effective against the inflammatory response elicited by carrageenan (70% inhibition) as compared to MeDL (50% inhibition) at 20microg/kg dose. On the other hand, PBZ effectively inhibited the inflammatory response elicited by both MeDL and carrageenan, while DEX was more effective against carrageenan. Thus, our study indicates that the difference in the anti-inflammatory effect of IL-1beta against latex of C. procera extract and carrageenan is due to the release of different mediators released by these inflammagens.

  5. Development of a Specific Latex Agglutination Test to Detect Antibodies of Enterovirus 71.

    Science.gov (United States)

    Qin, Bo; Zhang, Jianhua; Xie, Wenhao; Liu, Xuehong; He, Tingting; Chen, Jinkun; Dong, Xuejun

    2015-10-01

    A latex agglutination test (LAT) was developed for the rapid detection of antibodies against the VP1 or VP1 proteins of Enterovirus 71 (EV71). The proteins of interest including prokaryotically expressed VP1 and two strains of anti-VP1 monoclonal antibody (McAb) against EV71 were covalently linked to carboxylated latex using ethyl-dimethyl-amino-propyl carbodiimide (EDC) to prepare sensitized latex beads. LAT was evaluated by an enzyme-linked immunosorbent assay (ELISA) as a reference test. The VP1-LAT showed a sensitivity of 87.0%, specificity of 88.9%, and an agreement ratio of 90.0% in detecting VP1 in 100 serum samples from experimentally infected mice, whereas these values were 86.8, 96.7, and 93.3%, respectively, for 608 clinical human serum samples. The VP1-LAT has advantages over other assays in terms of low cost, rapidity, chemical stability, high sensitivity, repeatability, and specificity. The LAT established in the present study is a rapid and simple test suitable for field monitoring of antibodies against VP1-EV71.

  6. Biosynthesis of silver nanoparticles using latex from few Euphorbian plants and their antimicrobial potential.

    Science.gov (United States)

    Patil, Satish V; Borase, Hemant P; Patil, Chandrashekhar D; Salunke, Bipinchandra K

    2012-06-01

    The synthesis of well-dispersed and ultrafine metal nanoparticles has great interest due to their distinctive physicochemical properties and biomedical applications. This study is the first report of one-step solvent-free synthesis of AgNPs using Euphorbiaceae plant latex. Among evaluated eight latex-producing plants, four (Jatropha curcas, Jatropha gossypifolia, Pedilanthus tithymaloides, and Euphorbia milii) showed high potential to produce physicochemically distinct, small-sized and bactericidal AgNPs. Phytochemical screening showed presence of rich amount of biochemicals in these plants. J. gossypifolia showed uniformly dispersed comparatively small-sized AgNPs. Dose-dependent growth inhibition of bacterial pathogens Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermis, and Micrococcus luteus was observed for J. gossypifolia latex-synthesized AgNPs with minimum inhibitory concentration values 30, 40, 70, 60, and 60 ppm, respectively, after 24 h. Possible mode of action of AgNPs against pathogens was confirmed by analyzing enzymes and cell leakage.

  7. Latex-mediated synthesis of ZnS nanoparticles: green synthesis approach

    Energy Technology Data Exchange (ETDEWEB)

    Hudlikar, Manish; Joglekar, Shreeram [University of Pune, Division of Biochemistry, Department of Chemistry (India); Dhaygude, Mayur [National Chemical Laboratory, Polymer Science and Engineering Division (India); Kodam, Kisan, E-mail: kodam@chem.unipune.ac.in [University of Pune, Division of Biochemistry, Department of Chemistry (India)

    2012-05-15

    A low-cost, green synthesis of ZnS nanoparticles is reported using 0.3 % latex solution prepared from Jatropha curcas L. ZnS nanoparticles were characterized by X-ray diffraction, selected area electron diffraction, transmission electron microscopy, energy dispersive analysis of X-rays, UV-vis optical absorption and photoluminescence techniques. Fourier Transform Infrared Spectroscopy was performed to find the role of cyclic peptides namely curcacycline A (an octapeptide), curcacycline B (a nonapeptide) and curcain (an enzyme) as a possible reducing and stabilizing agents present in the latex of J. curcas L. The average size of ZnS nanoparticles was found to be 10 nm. Latex of J. curcas L. itself acts as a source of sulphide (S{sup -2}) ions that are donated to Zn ions under present experimental conditions. Source of sulphide (S{sup -2}) ions is still unclear, but we speculate that cysteine or thiol residues present in enzyme curcain may be donating these sulphide (S{sup -2}) ions.

  8. Crystallization and preliminary X-ray diffraction studies of the glutaminyl cyclase from Carica papaya latex

    Energy Technology Data Exchange (ETDEWEB)

    Azarkan, Mohamed [Laboratoire de Chimie Générale I, Faculté de Médecine-ULB CP609, 808 Route de Lennik, B-1070 Brussels (Belgium); Clantin, Bernard; Bompard, Coralie [CNRS-UMR 8525, Institut de Biologie de Lille, BP 477, 1 Rue du Professeur Calmette, F-59021 Lille (France); Belrhali, Hassan [EMBL Grenoble Outstation, 6 Rue Jules Horowitz, BP 181, F-38042 Grenoble CEDEX 9 (France); Baeyens-Volant, Danielle [Laboratoire de Chimie Générale I, Faculté de Médecine-ULB CP609, 808 Route de Lennik, B-1070 Brussels (Belgium); Looze, Yvan [Laboratoire de Chimie Générale, Institut de Pharmacie-ULB CP206/04, Boulevard du Triomphe, B-1050 Brussels (Belgium); Villeret, Vincent, E-mail: vincent.villeret@ibl.fr [CNRS-UMR 8525, Institut de Biologie de Lille, BP 477, 1 Rue du Professeur Calmette, F-59021 Lille (France); Wintjens, René, E-mail: vincent.villeret@ibl.fr [Laboratoire de Chimie Générale, Institut de Pharmacie-ULB CP206/04, Boulevard du Triomphe, B-1050 Brussels (Belgium); Laboratoire de Chimie Générale I, Faculté de Médecine-ULB CP609, 808 Route de Lennik, B-1070 Brussels (Belgium)

    2005-01-01

    The glutaminyl cyclase isolated from C. papaya latex has been crystallized using the hanging-drop method. Diffraction data have been collected at ESRF beamline BM14 and processed to 1.7 Å resolution. In living systems, the intramolecular cyclization of N-terminal glutamine residues is accomplished by glutaminyl cyclase enzymes (EC 2.3.2.5). While in mammals these enzymes are involved in the synthesis of hormonal and neurotransmitter peptides, the physiological role played by the corresponding plant enzymes still remains to be unravelled. Papaya glutaminyl cyclase (PQC), a 33 kDa enzyme found in the latex of the tropical tree Carica papaya, displays an exceptional resistance to chemical and thermal denaturation as well as to proteolysis. In order to elucidate its enzymatic mechanism and to gain insights into the structural determinants underlying its remarkable stability, PQC was isolated from papaya latex, purified and crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 62.82, b = 81.23, c = 108.17 Å and two molecules per asymmetric unit. Diffraction data have been collected at ESRF beamline BM14 and processed to a resolution of 1.7 Å.

  9. Cake layer reduction by gas sparging cross flow ultrafiltration of skim latex serum

    Directory of Open Access Journals (Sweden)

    Harunsyah Nik Meriam Sulaiman

    2002-11-01

    Full Text Available A gas sparged method was investigated for reducing cake layer formation and enhancing the crossflow ultrafiltration process. The injection of nitrogen gas promotes turbulence and increases the permeate flux of the process fluid. Experiments were carried out using a tubular membrane (100 kDa MWCO,mounted vertically with skim latex serum, which results from the coagulation of skim latex by-product. The objective of this research was focused mainly on the observed reversible cake resistance during the cross flow ultrafiltration of skim latex serum. The effect of operating parameters, including feed flow rate, flowrate gas sparging and transmembrane pressure ware investigated. Results obtained thus far show that the use of gas sparged technique has been able to enhance total permeate flux in the range 8.29% to 145.33% compared to non-gas sparged condition. In this research optimum permeate flux was obtained at a feed flowrate of 1400 ml/min, a flowrate gas sparging of 500 ml/min and a transmembrane pressure of 0.89 barg.

  10. Rubber recovery from centrifuged natural rubber latex residue using sulfuric acid

    Directory of Open Access Journals (Sweden)

    Wirach Taweepreda

    2013-04-01

    Full Text Available Waste latex sludge from centrifuged residue, which is a null by-product of concentrated latex manufacturing, wasdigested to retrieve the rubber by using sulfuric acid. It was found that the acid concentration and digestion time have aneffect on the amount and purity of the retrieved rubber. Sulfuric acid at concentrations of more than 10% by weight with adigestion time of 48 hours completely digested waste latex sludge and gave rubber 10% by weight. The quality of the retrievedrubber was examined for Mooney viscosity (MV, plasticity retention index, nitrogen content, and ash content. The averagemolecular weight of the retrieved rubber, using gel permeation chromatography, was lower than that of normal natural rubber(NR which corresponds with the MV and initial plasticity (Po. The molecular structure from Fourier transform infraredspectroscopy (FT-IR indicated that the retrieved rubber surface is wet composed with hydroxyl functional ended group.The residue solution was evaporated and crystallized. The structure of crystals was determined using power X-ray diffractometer.

  11. A simple rectangular microstrip technique for determination of moisture content in Hevea rubber latex

    Science.gov (United States)

    Yahaya, Nor Zakiah; Abbas, Zulkifly; Norimi, Amizadillah Md; Yahaya, Muhamad Zamri; Razak, Nik Noor Ashikin Abd; Mustafa, Iskandar Shahrim

    2015-08-01

    A simple rectangular microstrip sensor for determination of moisture content in Hevea Rubber Latex is presented in this paper. The microstrip patch sensor was designed to operate at microwave frequency range from 1 to 5 GHz on a RT/Duroid substrate with 6.15 ±0.015 permittivity and 1.27 mm thickness. The width and length of the rectangular patch antenna was 18 mm and 38 mm, respectively. The reflection coefficient of the sensor loaded with Hevea latex at various percentages of moisture content from approximately 36.1% to 88.6 %. Calibration equations have been established between moisture content and phase of reflection coefficient at several selected frequencies. These equations were used to predict the amount of moisture content on Hevea latex based on the measured reflection coefficient values. The actual values of moisture content were obtained using standard oven drying method. The lowest mean relative error between actual and predicted moisture contents was 0.04 at 1 GHz.

  12. Antiinflammatory Efficacy of Extracts of Latex of Calotropis procera Against Different Mediators of Inflammation

    Directory of Open Access Journals (Sweden)

    Soneera Arya

    2005-01-01

    Full Text Available The latex of the plant Calotropis procera has been reported to exhibit potent antiinflammatory activity against carrageenin and formalin that are known to release various mediators. In the present study, we have evaluated the efficacy of extracts prepared from the latex of C procera against inflammation induced by histamine, serotonin, compound 48/80, bradykinin (BK, and prostaglandin E(PGE in the rat paw oedema model. The paw oedema was induced by the subplantar injection of various inflammagens and oedema volume was recorded using a plethysmometer. The aqueous and methanol extracts of the dried latex (DL and standard antiinflammatory drugs were administered orally 1 hour before inducing inflammation. The inhibitory effect of the extracts was also evaluated against cellular influx induced by carrageenin. The antiinflammatory effect of aqueous and methanolic extracts of DL was more pronounced than phenylbutazone (PBZ against carrageenin while it was comparable to chlorpheniramine and PBZ against histamine and PGE, respectively. Both extracts produced about 80%, 40%, and 30% inhibition of inflammation induced by BK, compound 48/80, and serotonin. The histological analysis revealed that the extracts were more potent than PBZ in inhibiting cellular infiltration and subcutaneous oedema induced by carrageenin. The extracts of DL exert their antiinflammatory effects mainly by inhibiting histamine and BK and partly by inhibiting PGE.

  13. Comparison of the latex agglutination test with the hemagglutination inhibition test, enzyme-linked immunosorbent assay, and neutralization test for detection of antibodies to rubella virus.

    OpenAIRE

    Meegan, J M; Evans, B. K.; Horstmann, D. M.

    1982-01-01

    The ability of a rapid, latex agglutination test to diagnose rubella infection and to measure immune status was evaluated by comparison with the hemagglutination-inhibition (HAI) test, enzyme-linked immunosorbent assay (ELISA), and the neutralization (NT) test. The latex agglutination test accurately detected serological conversions in 74 pairs of sera representing 21 natural infections and 53 immunizations. The antibody levels of 276 sera from the general population were determined by latex ...

  14. Prevalence and clinical impact of sensitization to latex and fruits in dentistry students at the University of Antioquia, and its relationship with allergy to fruits

    Directory of Open Access Journals (Sweden)

    Echenique Manrique, Alejandro

    2015-04-01

    Full Text Available Objective: To determine the prevalence and clinical impact of sensitization to latex and to five tropical fruits (banana, avocado, kiwi, pineapple and passion fruit in dentistry students. Methods: Analytical cross-sectional study of 128 dentistry students at University of Antioquia in Medellín, Colombia. Information was collected by means of a questionnaire and skin prick tests with latex and fruits were done. Results: All students reported having had contact with latex. Nine of them informed at least one episode of adverse reaction to contact with latex without proof of sensitization to it. Five reported at least one reaction with one of the fruits, but skin prick tests were negative. Four of the 14 students who reported gastrointestinal symptoms were sensitized to latex or to one of the tested fruits. Overall, latex sensitization rate was 3.1%. Conclusion: This percentage of sensitization to latex is lower than that in other studies; this may be due to the expression of immune mechanisms other than IgE mediation. We failed to demonstrate a higher sensitization rate to latex as students advanced in their career. The association between gastrointestinal symptoms and sensitization to both fruit and latex is to be emphasized.

  15. Use of the Directigen Latex Agglutination Test for Detection of Haemphilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis Antigens in Cerebrospinal Fluid from Meningitis Patients,

    Science.gov (United States)

    Reprint: Use of the Directigen Latex Agglutination Test for Detection of Haemphilus influenzae, Streptococcus pneumoniae , and Neisseria meningitidis Antigens in Cerebrospinal Fluid from Meningitis Patients.

  16. Properties of natural rubber latexes modified by different processes%不同改性方法对天然胶乳的性能影响

    Institute of Scientific and Technical Information of China (English)

    廖小雪; 唐冰; 吴翠; 谭海生

    2011-01-01

    The natural rubber (NR) latex modified by chlorinated paraffin and antimony oxide blending was prepared; the NR latex addition polymerizaion modified by trichlorobromomethane was prepared;the NR latex graft copolymerization modified by tribromopropylene was prepared. A comparison of the colloidal properties, flame-resistance properties and solvent-resistance properties was made between NR latex and the three kinds of modified latex. The results showed that the viscosity of the three kinds of modified latex was higher than the non-modified latex' s, the viscosity of graft copolymerization and halogenation modified latex changed greatly,blend modified latex's viscosity had little change; the flame-resistance properties of the three kinds of modified latex were higher than the nonmodified latex's; solvent-resistance of the films of graft copolymerization modified latex and halogenation modified latex was superior to the films of non-modified latex's, solvent-resistance of the films of blend modified latex was worse than the ones of non-modified latex's.%分别采用氯化石蜡与Sb2O3共混改性天然胶乳、用三氯澳甲烷卤化加成改性天然胶乳、以3-澳丙烯接枝共聚改性天然胶乳,对3种不同工艺所制备的改性天然胶乳与未改性天然胶乳进行了胶体性能、阻燃性及耐溶剂性能的比较.研究结果表明:3种改性胶乳的粘度比未改性天然胶乳的要高,且接枝改性胶乳和卤化改性胶乳变化较大,共混改性胶乳的变化较少;3种改性胶乳的阻燃性能高于未改性天然胶乳的;卤化改性天然胶乳和接枝改性天然胶乳的耐溶剂性较好,而共混改性天然胶的耐溶剂性较差.

  17. Evaluation of the MycoAKT latex agglutination test for rapid diagnosis of Mycobacterium avium complex infections.

    Science.gov (United States)

    Olano, J P; Holmes, H; Woods, G L

    1998-01-01

    Rapid diagnosis of Mycobacterium avium complex (MAC) bacteremia is important for management of patients with the acquired immunodeficiency syndrome who have disseminated MAC. The purpose of this study was to determine the reliability of the MycoAKT latex agglutination test for direct detection of MAC in positive mycobacterial blood cultures. First, colonies of isolates of previously identified mycobacteria, including 35 MAC, were tested. Of the 55 isolates evaluated, 33 were identified as MAC by the latex test, including 31 of the known MAC and 2 M. chelonae (sensitivity, 88.6%; specificity, 90.0%). Second, broth from 20 ESP II and 20 BACTEC 12B bottles seeded with isolates of MAC were tested. Aliquots from 19 (95%) ESP II cultures and 16 (80%) 12B cultures were positive by the latex test. In phase 3, broth from 115 signal-positive ESP II blood cultures were tested by latex agglutination. Forty-three subcultures from these bottles grew mycobacteria (41 MAC and 2 Mycobacterium tuberculosis complex); the remainder grew no organisms. Broth from 40 of the blood cultures (39 that grew MAC and 1 from which no organisms were recovered) were latex positive; thus, the sensitivity, specificity, and positive and negative predictive values of the latex test for direct identification of MAC in ESP II blood cultures were 95.1, 98.6, 97.5, and 97.3%, respectively. The mean time to detection of MAC was 14.6 days (range, 6-34 days) with the direct latex test, compared with 18.3 days (range, 9-36 days) with subculture and probe (p < 0.05).

  18. Graphs: Associated Markov Chains

    OpenAIRE

    2012-01-01

    In this research paper, weighted / unweighted, directed / undirected graphs are associated with interesting Discrete Time Markov Chains (DTMCs) as well as Continuous Time Markov Chains (CTMCs). The equilibrium / transient behaviour of such Markov chains is studied. Also entropy dynamics (Shannon entropy) of certain structured Markov chains is investigated. Finally certain structured graphs and the associated Markov chains are studied.

  19. 保存剂对天然胶乳中白坚木皮醇含量的影响%Study on the Contents of Quebrachitol in Natural Latex with Different Latex Preservatives Treating

    Institute of Scientific and Technical Information of China (English)

    邓瑶筠; 敖宁建

    2005-01-01

    The fresh natural rubber latex were treated by different latex preservatives, including ammonia aqua, ammonia aqua/investigated. The results show that the releasing and extraction of quebrachitol in natural latex were hindered by latex preserva-tive. The extraction rate of quebrachitol in the field latex serum without preservative treatment is 0.15% and the average ex-0.06%, 0.07% and 0.04% respectively.%用氨水、氨/硼酸、氨/TT·氧化锌和苯甲酸钠4种胶乳保存剂处理PR107品系天然胶乳,研究胶乳中白坚木皮醇含量的变化.结果表明,胶乳保存剂阻碍胶乳中白坚木皮醇的释出和提取,未经保存剂处理的新鲜胶乳乳清,其白坚木皮醇的提取率可达0.15%,经氨水、氨/TT·氧化锌和氨/硼酸保存剂处理的胶乳乳清,其白坚木皮醇的平均提取率分别为0.06%,0.07%和0.04%.

  20. Patchy particle packing under electric fields.

    Science.gov (United States)

    Song, Pengcheng; Wang, Yufeng; Wang, Yu; Hollingsworth, Andrew D; Weck, Marcus; Pine, David J; Ward, Michael D

    2015-03-01

    Colloidal particles equipped with two, three, or four negatively charged patches, which endow the particles with 2-fold, 3-fold, or tetrahedral symmetries, form 1D chains, 2D layers, and 3D packings when polarized by an AC electric field. Two-patch particles, with two patches on opposite sides of the particle (2-fold symmetry) pack into the cmm plane group and 3D packings with I4mm space group symmetry, in contrast to uncharged spherical or ellipsoidal colloids that typically crystallize into a face-centered ABC layer packing. Three-patch particles (3-fold symmetry) form chains having a 21 screw axis symmetry, but these chains pair in a manner such that each individual chain has one-fold symmetry but the pair has 21 screw axis symmetry, in an arrangement that aligns the patches that would favor Coulombic interactions along the chain. Surprisingly, some chain pairs form unanticipated double-helix regions that result from mutual twisting of the chains about each other, illustrating a kind of polymorphism that may be associated with nucleation from short chain pairs. Larger 2D domains of the three-patch particles crystallize in the p6m plane group with alignment (with respect to the field) and packing densities that suggest random disorder in the domains, whereas four-patch particles form 2D domains in which close-packed rows are aligned with the field.