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Latex
Kinds of Latex Terms modified by Latex Selected AbstractsA New Method of Reproduction of Fingerprints from Corpses in a Bad State of Preservation Using LatexJOURNAL OF FORENSIC SCIENCES, Issue 6 2007Davide Porta B.Sc. Abstract:, In view of the problems arising while fingerprinting corpses in a bad state of preservation, especially in case of mummification and carbonization, the authors propose an innovative technique which uses latex film. To better illustrate the potential of the method, two cases where the latex technique was applied successfully are reported: the first one is a mummified body discovered in a shack on the outskirts of Milan and the second one is the case of a burnt corpse found in a car boot. Such a technique is versatile, easy to apply, and allows the operator to work quickly on cadavers without amputating parts, except in rare cases (i.e., burnt bodies with muscle retraction). By the latex technique, a perfect and enduring negative copy of the fingerprint is obtained, ready to be inked and photographed. The numerous copies produced this way can be inked several times allowing for the repeatability of the procedure and this is crucial in cases of problematic legal identification of corpses. In both the cases illustrated, the fingerprints obtained by the latex technique were useful for identification. The quality was good enough for the automatic fingerprint identification system research system to be applied. [source] Influence of Stabilizer Concentration on Transport Behavior and Thermopower of CNT-Filled Latex-Based CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2010Yeon Seok Kim Abstract The influence of the stabilizer/SWNT ratio on the transport behavior of latex-based polymer nanocomposites is examined in an effort to improve electrical conductivity while maintaining or improving the Seebeck coefficient (i.e., thermopower). Results show that phonon and electron transport are significantly affected by tube/tube junctions, and the carrier transport across the junctions can be manipulated by altering the stabilizer concentration. Electrical conductivity of composites containing 10,wt.-% SWNT nearly doubles, becoming greater than 900,S,·,m,1, by changing the SWNT:GA ratio from 1:3 to 10:1, while thermal conductivity and Seebeck coefficient remain relatively constant (near 0.25,W,·,m-K,1 and 40,µV,·,K,1, respectively). [source] Synthesis of High Solid-Content Latex using Alkali-Soluble Resin as Sole SurfactantMACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 2004Marcelo do Amaral Abstract Summary: A novel polymerization procedure to synthesize latex stabilized by alkali-soluble resin (ASR) is detailed. According to this process, latexes with a high solid content and low viscosity are obtained using a substantially lower amount of ASR when compared with existing techniques. Similar rewet properties were found for the latexes obtained by a standard process and for the one obtained by the process described in this work. Comparison of the particle size distributions obtained by conventional emulsion polymerization (,) and by miniemulsion polymerization (,). [source] Morphologies and applied properties of PSI/PA composite particles synthesized at low temperaturePOLYMER COMPOSITES, Issue 11 2008Yumin Wu Latex with a poly(dimethyl-siloxane) core and a poly(methylmethacrylate- butylacrylate- 2-hydroxypropyl acrylate) shell have been prepared at low temperature with potassium-persulphate (KPS), sodium formaldehyde sulfoxylate (SFS) and 2,2,-azobis [2-(2-imidazolin- 2-yl)propane] dihydrochloride (VA-044) as composite initiators by staged emulsion polymerization. Reactive surfactants were used to significantly improve the applied properties such as water adsorption ratio and thermo-properties. Transmission electron microscopy (TEM) results indicated that increasing the amount of 2-hydroxypropyl acrylate (HPA) and butylacrylate (BA) was favorable to form the core/shell particles. Particle size distribution results showed with increasing the dosages of surfactants, initiators, and seed-latex, particle size decreased. Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) results indicated the high temperature-reserved of copolymer was improved in the presence of polysiloxane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] The production of high polymer to surfactant microlatexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Raul P. Moraes Abstract Starved-feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1-pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48,54, 2010 [source] Unexpected Crosslinking During Acetoacetoxy Group Protection on Waterborne Crosslinkable LatexesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006Ińigo González Abstract Summary: The microstructure of the polymer synthesized by seeded semicontinuous emulsion copolymerization of AAEMA was investigated. It was found that the neutralization of the latexes with ammonia to protect acetoacetoxy functionality against hydrolysis during storage had a remarkable effect on the gel content. A base catalyzed Michael addition reaction between acetoacetoxy groups and terminal double bond (TDB) is proposed as responsible for the chain precrosslinking observed. The presence of TDB in the latexes was demonstrated by means of 1H NMR. Moreover, the chain precrosslinking affected the subsequent crosslinking reaction of the latex with diamines hindering chain interdiffusion and yielding poorer mechanical properties. Michael addition between AcAc functional groups and TDB, and final gel content of the MMA/BA/MAA latexes with different amounts of AAEMA. [source] Empirical Modeling of Butyl Acrylate/Vinyl Acetate/Acrylic Acid Emulsion-Based Pressure-Sensitive AdhesivesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2004Renata Jovanovic Abstract Summary: Butyl acrylate/vinyl acetate/acrylic acid (BA/VAc/AA) emulsion latexes were produced in a semi-batch mode. The objective was to generate polymers with properties favoring their application as pressure-sensitive adhesives. The influence of the individual monomer concentrations on final properties such as glass transition temperature (Tg), peel strength, shear strength and tack was investigated. To obtain the maximum amount of information in a reasonable number of runs, a constrained three-component mixture design was used to define the experimental conditions. Latexes were coated onto a polyethylene terephthalate carrier and dried. Different empirical models (e.g. linear, quadratic and cubic mixture models) governing the individual properties (i.e. Tg, peel adhesion, shear resistance and tack) were developed and evaluated. In the given experimental region, no single model was found to fit all of the responses (i.e. the final properties). However, in all models the most significant factor affecting the final properties was the AA concentration, followed by the VAc concentration. Shear strength contour lines over the investigated region. [source] Coagulation of Carboxylic Acid-Functionalized LatexesMACROMOLECULAR SYMPOSIA, Issue 1 2008Adélia Santos Abstract In the present work, the stability of particles produced by emulsion polymerization and stabilized by carboxylic acid groups was studied from turbidity measurements. To achieve this, a number of copolymerization runs was carried out under different reaction conditions, including the use of different carboxylic monomers. Partitioning analyses using conductimetric and potentiometric titrations were performed in order to assess the distribution of carboxylic monomers among the main phases of the produced latexes. Additionally, the stability and coalescence of particles were measured by turbidimetry in a diluted latex considering either the presence or not of the anionic surfactant sodium lauryl sulfate. Coalescence of particles was provoked in the latex samples at different temperatures by addition of an aliquot of a concentrated solution of electrolyte. The influence of surfactant, temperature and type of carboxylic acid group on the particle stability was investigated. [source] Immediate and delayed hypersensitivity reactions to food and latex in a chefCONTACT DERMATITIS, Issue 3 2006M. E. Laing No abstract is available for this article. [source] FC03.1 Experience from joint occupational health/dermatology clinicsCONTACT DERMATITIS, Issue 3 2004Yat Wing Wong Background:, A monthly consultant led occupational health/dermatology clinic was started in 1999 providing rapid access to staff with suspected occupational skin disease including natural rubber latex (NRL) allergy and teaching for the occupational health staff. Objectives:, To evaluate the characteristics and outcome of staff attending this clinic and to assess patient satisfaction. Methods:, A retrospective case note survey was performed from staff attending the clinic from 1999 to 2002. A questionnaire was sent to them >3 months following consultation. Results:, A total of 116 patients were identified (12 male, 104 female), and 85 (73%) were nurses. 77 (66%) patients were referred with hand eczema (HE). Of the 45 patients referred with adverse reactions or exacerbation of hand dermatitis following the use of latex gloves, only 4 had positive prick tests and were considered to have NRL allergy. Patients with significant HE or occupational exacerbation of HE were referred for patch testing (n = 36). Of the remainder, most could be discharged after a single visit. 49/95 (52%) questionnaires were returned, 34/45 (76%) patients found the consultation useful. As a separate study, the data recorded within the patch test clinic looking at health care workers (HCW) referred both from this clinic and from other sources was analysed. This showed relevant positive patch tests in 16/49 (33%) patients. In 55/99 (56%), an occupational cause was likely. Conclusion:, Occupational skin disease in HCW is common, attendance at the clinic was beneficial and a single visit was sufficient in most cases. [source] P03 Type-I and -IV hypersensitivity to platinum saltsCONTACT DERMATITIS, Issue 3 2004Willeke Kamphof A 28-year-old female analytical chemist visited our patch test clinic with initially complaints of severe hand dermatitis. Later on she developed rhinitis, bronchial asthma and tightness of the chest. The complaints seemed work related: her condition improved during holidays and on sick leaves. She worked in a laboratory with several platinum salts and used different kinds of gloves (latex, nitril, etc.). Methods:, Patch tests were performed with the European Standard series and prick tests with common inhalant allergens. Patch-, prick- and open patch tests were carried out with various aqueous dilutions of platinum chloride (PtCl2). Results:, Patch tests with 0.01,2% PtCl2 were positive on day 2, 3 and 6, and at 0.001% a follicular reaction was found. The prick-test was already positive at the lowest concentration tested (0.001%). The open patch test, carried out retro-auricular, showed a positive reaction at 1 and 2% PtCl2 after 20 min. Controls in healthy volunteers (n = 5) were all negative. Discussion:, It is well known that platinum salts can cause type-I hypersensitivity reactions like allergic rhinitis, conjunctivitis, bronchial asthma and urticaria, also referred to as platinosis. Contact dermatitis to platinum salts, however, is very rare. In our patch test clinic, 78 patients were tested between 1987 and 2001 with PtCl2 2%. Only 2 women showed a positive patch test for PtCl2. The patient presented here, stopped working with platinum salts and recovered from all complaints. We interpret our case as occupational type-I and type-IV hypersensitivity to platinum salts with mucosal and dermal manifestations. [source] The use of protective gloves and the prevalence of hand eczema, skin complaints and allergy to natural rubber latex among dental personnel in the county of Uppsala, SwedenCONTACT DERMATITIS, Issue 1 2000Magnus Lindberg During the past decade, there has been an increasing problem with acrylate allergy and natural rubber latex (NRL) allergy among dental personnel. The aim of the present study was to evaluate the prevalence of these problems among dentists, dental nurses and dental hygienists in Uppsala county, Sweden. The study was based on a self-administered questionnaire sent to 690 persons with 527 responders (76%). The most common skin problem was dry skin, fissures and/or itching on the hands. Of the 72 persons (13.6%) reporting to have suffered from hand eczema during the past 12 months, 41 were patch tested with the TRUE Test standard series and the Swedish dental screening series. In the patch tested group, 9.8% reacted to 1 or more of the acrylates. In addition, 389 persons were tested for NRL allergy with the Pharmacia Upjohn CAP-RAST test, and of these, we found 7.2% to be positive. The prevalence of self-reported hand eczema and the number of positive CAP-RAST tests differed between the 3 occupations, with higher figures for the dentists. There was also a correlation between atopic eczema and hand eczema. Of those reporting skin symptoms, 67.7% connected them to the place of work and 28.8% related them to the use of gloves. [source] Latex allergy: diagnosis and managementDERMATOLOGIC THERAPY, Issue 4 2004James S. Taylor ABSTRACT:, Latex allergy is an IgE-mediated immediate hypersensitivity response to natural rubber latex (NRL) protein with a variety of clinical signs ranging from contact urticaria, angioedema, asthma, and anaphylaxis. Major allergens include dipped latex products such as gloves and balloons. In highest risk for NRL allergy are patients with spina bifida, but health care workers and others who wear latex gloves are also at risk. NRL allergic patients may also react to fruits/foods, especially banana, kiwi, and avocado. Diagnosis is made by a positive latex RAST and/or skin prick test or challenge test to NRL. Allergen avoidance and substitution and the use of latex-safe devices including synthetic gloves (vinyl, synthetic polyisoprene, neoprene, nitrile, block polymers, or polyurethane) are essential for the affected patient. Accommodation in the workplace may include the use of powder-free, low-allergen NRL gloves or synthetic gloves. These preventive measures have significantly reduced the prevalence of reported reactions to NRL. Hyposensitization is not yet feasible. [source] Sabotaging behaviour and minimal latex of Asclepias curassavica incur no cost for larvae of the southern monarch butterfly Danaus erippusECOLOGICAL ENTOMOLOGY, Issue 4 2010DANIELA RODRIGUES 1. The southern monarch, Danaus erippus, uses mainly Asclepias curassavica as its host in the Neotropics, a plant species bearing articulated anastomosing laticifers. When artificially severed, A. curassavica has been shown to release significantly less latex than other Asclepias species. 2. The present study tested the hypothesis that sabotaging behaviour changes during the ontogeny of D. erippus and recorded latex outflow of A. curassavica during sabotaging and feeding. Larvae displayed vein-cutting behaviour, which was initially observed in the second instar, became more pronounced in the third and fourth instars, and less frequent in the fifth instar. When present, latex outflow was never more than 1 µl at a time during either vein cutting or feeding, regardless of the instar. 3. Mandibular and midrib morphometrics revealed that larvae selected thicker midrib sites for severing as instars progressed; however, no correlation between mandibular size and midrib size severed was found within instars. 4. Costs of sabotaging behaviour and the effects of A. curassavica latex outflow on D. erippus larvae were also examined. Sabotaging behaviour did not incur growth costs for larvae, and only latex exudation volumes at least 10-fold greater than those observed due to D. erippus sabotaging or feeding, caused significantly higher larval mortality than controls. 5. Since latex outflow is minimal or non-existent in A. curassavica, sabotaging behaviour in D. erippus is mostly limited by morphological constraints and is probably driven by chemical stimulants rather than latex defence. In turn, latex does not constitute a major defence of A. curassavica against D. erippus. [source] Rapid detection of Staphylococcus aureus by a combination of monoclonal antibody-coated latex and capillary electrophoresisELECTROPHORESIS, Issue 9 2006Peng Gao Abstract The rapid detection of pathogenic bacteria is extremely important in biotechnology and clinical diagnosis. CE has been utilized in the field of bacterial analysis for many years, but to some extent, simultaneous separation and identification of certain microbes from complex samples by CE coupled with UV detector is still a challenge. In this paper, we propose a new strategy for rapid separation and identification of Staphylococcus aureus (S.,aureus) in bacterial mixtures by means of specific mAb-coated latex coupled with CZE. An appropriate set of conditions that selectively isolated S.,aureus from the microorganisms Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae were established. S.,aureus could be differentiated from the others by unique peaks in the electropherograms. The validity was also confirmed by LIF with antibodies specific to both the latex and the microbial cells. The LOD is as low as 9.0×105 colony forming unit/mL. We have also utilized this technology to identify S.,aureus in a stool sample coming from a healthy volunteer spiked successfully with S.,aureus. This CZE-UV technique can be applied to rapid diagnosis of enteritis caused by S.,aureus or other bacterial control-related fields needing rapid identification of target pathogens from microbial mixtures. In theory, this method is suitable for the detection of any bacterium as long as corresponding bacterium-specific antibody-coated latex is available. [source] Evolution of latex and its constituent defensive chemistry in milkweeds (Asclepias): a phylogenetic test of plant defense escalationENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2008Anurag A. Agrawal Abstract A tremendous diversity of plants exude sticky and toxic latex upon tissue damage, and its production has been widely studied as a defensive adaptation against insect herbivores. Here, we address variation in latex production and its constituent chemical properties (cardenolides and cysteine proteases) in 53 milkweeds [Asclepias spp. (Apocynaceae)], employing a phylogenetic approach to test macroevolutionary hypotheses of defense evolution. Species were highly variable for all three traits, and they showed little evidence for strong phylogenetic conservatism. Latex production and the constituent chemical defenses are thus evolutionarily labile and may evolve rapidly. Nonetheless, in phylogenetically independent analyses, we show that the three traits show some correlations (and thus share a correlated evolutionary history), including a positive correlation between latex exudation and cysteine protease activity. Conversely, latex exudation and cysteine protease activity both showed a trade-off with cardenolide concentrations in latex. We also tested whether these traits have increased in their phenotypic values as the milkweeds diversified, as predicted by plant defense escalation theory. Alternative methods of testing this prediction gave conflicting results , there was an overall negative correlation between amount of evolutionary change and amount of latex exudation; however, ancestral state reconstructions indicated that most speciation events were associated with increases in latex. We conclude by (i) summarizing the evidence of milkweed latex itself as a multivariate defense including the amount exuded and toxin concentrations within, (ii) assessing the coordinated evolution of latex traits and how this fits with our previous notion of ,plant defense syndromes', and finally, (iii) proposing a novel hypothesis that includes an ,evolving community of herbivores' that may promote the escalation or decline of particular defensive strategies as plant lineages diversify. [source] Molecular cloning, expression and characterization of cDNA encoding cis -prenyltransferases from Hevea brasiliensisFEBS JOURNAL, Issue 23 2003A key factor participating in natural rubber biosynthesis Natural rubber from Hevea brasiliensis is a high molecular mass polymer of isoprene units with cis -configuration. The enzyme responsible for the cis -1,4-polymerization of isoprene units has been idengified as a particle-bound rubber transferase, but no gene encoding this enzyme has been cloned from rubber-producing plants. By using sequence information from the conserved regions of cis -prenyl chain elongating enzymes that were cloned recently, we have isolated and characterized cDNAs from H. brasiliensis for a functional factor participating in natural rubber biosynthesis. Sequence analysis revealed that all of the five highly conserved regions among cis -prenyl chain elongating enzymes were found in the protein sequences of the Hevea cis -prenyltransferase. Northern blot analysis indicated that the transcript(s) of the Hevea cis -prenyltransferase were expressed predominantly in the latex as compared with other Hevea tissues examined. In vitro rubber transferase assays using the recombinant gene product overexpressed in Escherichia coli revealed that the enzyme catalyzed the formation of long chain polyprenyl products with approximate sizes of 2 × 103,1 × 104 Da. Moreover, in the presence of washed bottom fraction particles from latex, the rubber transferase activity producing rubber product of high molecular size was increased. These results suggest that the Hevea cis -prenyltransferase might require certain activation factors in the washed bottom fraction particles for the production of high molecular mass rubber. [source] Hev b 9, an enolase and a new cross-reactive allergen from Hevea latex and moldsFEBS JOURNAL, Issue 24 2000Purification, characterization, cloning, expression Natural rubber latex allergy is an IgE-mediated disease that is caused by proteins that elute from commercial latex products. A complementary DNA (cDNA) coding for Hev b 9, an enolase (2-phospho- d -glycerate hydrolyase) and allergen from latex of the rubber tree Hevea brasiliensis, was amplified by PCR. The PCR primers were designed according to conserved regions of enolases from plants. The obtained cDNA amplification product consisted of 1651 bp and encoded a protein of 445 amino-acid residues with a calculated molecular mass of 47.6 kDa. Sequence comparisons revealed high similarities of the Hevea latex enolase to mold enolases that have been identified as important allergens. In addition, the crucial amino-acid residues that participate in the formation of the catalytic site and the Mg2+ binding site of enolases were also conserved. Hevea latex enolase was produced as a recombinant protein in Escherichia coli with an N-terminal hexahistidyl tag, and purified by affinity chromatography. The yield amounted to 110 mg of purified Hev b 9 per litre of bacterial culture. The recombinant allergen bound IgE from latex, as well as mold-allergic patients, in immunoblot and ELISA experiments. The natural enolase was isolated from Hevea latex by (NH4)2SO4 precipitation and ion exchange chromatography. The natural and the recombinant (r)Hev b 9 showed equivalent enzymatic activity. Patients' IgE-antibodies preincubated with rHev b 9 lost their ability to bind to natural (n) Hev b 9, indicating the identity of the B-cell epitopes on both molecules. Cross-reactivity with two enolases from Cladosporium herbarum and Alternaria alternata was determined by inhibition of IgE-binding to these enolases by rHev b 9. Therefore, enolases may represent another class of highly conserved enzymes with allergenic potentials. [source] Enzyme-Based Nanoscale Composites for Use as Active Decontamination SurfacesADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Cerasela Zoica Dinu Abstract Perhydrolase S54V (AcT) effectively catalyzes the perhydrolysis of propylene glycol diacetate (PGD) to generate peracetic acid (PAA). PAA is a potent oxidant used for sanitization and disinfection, with broad effectiveness against bacteria, yeasts, fungi, and spores. In this study, active and stable composites are developed by incorporating AcT,carbon nanotube conjugates into polymer and latex-based paint. At a conjugate loading of 0.16% (w/v), the composite generated 11,mM PAA in 20,min, capable of killing more than 99% spores initially charged at 106 colony-forming units per milliliter. [source] High-Conductivity Polymer Nanocomposites Obtained by Tailoring the Characteristics of Carbon Nanotube Fillers,ADVANCED FUNCTIONAL MATERIALS, Issue 20 2008Nadia Grossiord Abstract We present a detailed study of the influence of carbon nanotube (CNT) characteristics on the electrical conductivity of polystyrene nanocomposites produced using a latex-based approach. We processed both industrially-produced multi-wall CNT (MWCNT) powders and MWCNTs from vertically-aligned films made in-house, and demonstrate that while the raw CNTs are individualized and dispersed comparably within the polymer matrix, the electrical conductivity of the final nanocomposites differs significantly due to the intrinsic characteristics of the CNTs. Owing to their longer length after dispersion, the percolation threshold observed using MWCNTs from vertically-aligned films is five times lower than the value for industrially-produced MWCNT powders. Further, owing to the high structural quality of the CNTs from vertically-aligned films, the resulting composite films exhibit electrical conductivity of 103,S m,1 at 2,wt% CNTs. On the contrary, composites made using the industrially-produced CNTs exhibit conductivity of only tens of S m,1. To our knowledge, the measured electrical conductivity for CNT/PS composites using CNTs from vertically-aligned films is by far the highest value yet reported for CNT/PS nanocomposites at this loading. [source] Nanocomposite Foams: Conducting Nanocomposite Polymer Foams from Ice-Crystal-Templated Assembly of Mixtures of Colloids (Adv. Mater.ADVANCED MATERIALS, Issue 28 200928/2009) The cover shows an electron microscopy image of a nanocomposite "soft" polymer foam reinforced with armored cell walls of "hard" nanoparticles obtained by freeze-drying a mixture of colloids dispersed in water. On p. 2894 Stefan Bon and co-workers demonstrate the versatility of their ice-crystal templating assembly strategy by fabricating a gas sensor from a "soft" polymer latex, silica nanoparticles, and colloidal carbon black. [source] Synthesis of Light-Diffracting Assemblies from Microspheres and Nanoparticles in Droplets on a Superhydrophobic Surface,ADVANCED MATERIALS, Issue 22 2008Vinayak Rastogi Aqueous suspension droplets of monodisperse latex or latex and gold nanoparticles mixtures assume spherical shape on superhydrophobic substrates. The drying sessile droplets serve as macroscopic templates for assembling microspheres into closed-packed structures. Upon illumination, the supraparticles display discrete colored rings because of the periodic arrangement of latex particles in the surface layer. The physical origin of the colored patterns is explained in detail. [source] Enhanced Photocatalytic Performance of Brookite TiO2 Macroporous Particles Prepared by Spray Drying with Colloidal Templating,ADVANCED MATERIALS, Issue 10 2007F. Iskandar Macroporous particle photocatalysts can be produced using polystyrene latex (PSL) colloidal templating (see figure), which can be used for organic waste degradation. The rate of degradation is similar to that of nanoparticles. Macroporous particles have lower mechanical mobilities than nanoparticles and can be easily collected and recovered for repeated use. [source] Juvenile psoriatic arthritis with nail psoriasis in the absence of cutaneous lesionsINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2000Carola Duran-McKinster MD A 4-year-old white boy without a significant family history had morning stiffness and painful swelling of his left knee and ankle, right elbow, and dorsolumbar region of 2 months' evolution. The following laboratory studies were within normal limits: complete blood cell count, C-reactive protein (CRP), latex, antistreptolysin, and antinuclear antibodies. Rheumatoid factor was negative and an increase in the erythrocyte sedimentation rate (ESR) was detected (56 mm/h). The pediatric department made an initial diagnosis of juvenile rheumatoid arthritis, and treatment with acetylsalicylic acid at 100 mg/kg/day and naproxen at 10 mg/kg/day was started. A thick, yellowish toenail was diagnosed as onychomycosis. No mycologic investigations were performed. Intermittent episodes of painful arthritis of different joints were present. The radiographic features of the peripheral joints included: narrow joint spaces, articular erosions, soft tissue swelling, and diffuse bony demineralization. Characteristic bilateral sacroiliitis and a swollen tendon sheath on the left ankle were detected. At 11 years of age the nail changes had extended to five other toenails and to four fingernails, were yellow,brown in color, and showed marked subungual hyperkeratosis ( Figs 1, 2). The rest of the nails showed significant nail pitting. Trials of griseofulvin alternated with itraconazole in an irregular form for five consecutive years resulted in no clinical improvement, which prompted a consultation to our dermatology department. On three different occasions, KOH nail specimens were negative for fungus, but the presence of parakeratotic cells aroused the suspicion of psoriasis. A complete physical examination was negative for psoriatic skin lesions. A nail bed biopsy specimen was characteristic of nail psoriasis ( Fig. 3). Figure 1. Thickened nails with severe subungual hyperkeratosis in five fingernails Figure 2. Secondary deformity of nail plate. No "sausage" fingers were observed Figure 3. Light microscopic appearance of a nail biopsy specimen showing parakeratotic hyperkeratosis, elongation of interpapillary processes, and Munroe abscess (arrow) (hematoxylin and eosin stain, ×40) The following human leukocyte antigens (HLAs) were positive: A9, A10, B12, B27, Cw1, Bw4, DR6, DR7, DQ1, DQ2, and DR53. A diagnosis of juvenile psoriatic arthritis associated with nail psoriasis was made. Toenail involvement became so painful that walking became very difficult. Occlusive 40% urea in vaseline applied to the affected toenails for 48 h resulted in significant improvement. Currently, the patient is 20 years old with nail involvement, but no psoriatic skin lesions have ever been observed. [source] Suspected allergy to local anaesthetics: follow-up in 135 casesACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2010T. HARBOE Background: Local anaesthetics (LA) are generally considered safe with respect to allergy. However, various clinical reactions steadily occur. Even though most reactions are manifestations of reflexes to perceptive stimuli, uncertainty often remains regarding a possible allergic mechanism. This uncertainty later leads to an avoidance of local anaesthesia and unnecessarily painful interventions, resource-consuming general anaesthesia or even the risk of re-exposure to other yet unidentified allergens. In the present study, follow-up procedures at an allergy clinic were analysed to examine the frequency of identified causative agents and pathogenetic mechanisms and evaluate the strength of the diagnostic conclusions. Method: The medical records of 135 cases with alleged allergic reactions to LA were reviewed. Diagnoses were based on case histories, skin tests, subcutaneous challenge tests and in vitro IgE analyses. Results: Two events (1.5%) were diagnosed as hypersensitivity to LA, articaine,adrenaline and tetracaine,adrenaline, respectively. Ten reactions (7%) were diagnosed as IgE-mediated allergy to other substances including chlorhexidine, latex, triamcinolone and possibly hexaminolevulinate. As challenge testing was not consistently performed with the culprit LA compound, follow-ups were short of definitely refuting hypersensitivity in 61% of the cases. The reported clinical manifestations were in general diagnostically unspecific, but itch and generalised urticaria were most frequent in test-positive cases. Conclusion: Reactions during local anaesthesia are rarely found to be an IgE-mediated LA allergy. Whenever the clinical picture is compatible with allergy, other allergens should also be tested. [source] Stability and optimum polymerized condition of polysiloxane,polyacrylate core/shell polymerADVANCES IN POLYMER TECHNOLOGY, Issue 3 2010Chengyue Ge Abstract The stable emulsion of core/shell latex with little coagulum (no more than 0.5% in quality relative to total monomers) has been prepared at low temperature with potassium-persulfate (KPS), sodium formaldehyde sulfoxylate (SFS), and 2,2,-azobis(2-(2-imidazolin-2-yl)propane)dihydrochloride (VA-044) as composite initiators by staged emulsion polymerization. Reactive surfactants were used to significantly improve the stability of emulsion. More interestingly, reverse core/shell structure was investigated when the organic silicon was added in the late period of polymerization. The effects of the emulsifier, initiators, dosage of organic silicon, and monomer's content on conversion and graft efficiency were studied in detail. Moreover, the stability of emulsion was investigated by the values of zeta potential (,) and coagulum. More importantly, the thermal performance and stability of PSI/PA composite latex was studied by the glass transition temperature (Tg). The results showed that there are appropriate values for all factors to obtain high conversion, graft efficiency, and excellent stability: The dosage of surfactant was about 0.44 g, the dosage of VA-044 was about 1000 mg kg,1, the dosage of organic silicon was about 15%, and the monomer's content was about 30%. In addition, the introduction of organic silicon improved the Tg. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:161,172, 2010; View this article online at wileyonlinelibrary. DOI 10.1002/adv.20182 [source] Highly purified natural rubber by saponificaion of latex: Analysis of green and cured propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sureerut Amnuaypornsri Abstract Natural rubber (NR) was purified by saponification of fresh latex from Hevea brasiliensis and soaking process of the coagulum with aqueous NaOH solution. This treatment resulted in the decrease of nitrogen content to the same level as enzymatic deproteinized NR. The saponification of NR latex and soaking of the coagulum gave the rubber having good processability with easy to cure. The saponified rubber showed outstanding physical and dynamic mechanical properties such as high tensile properties, high storage modulus, low tan ,, low heat build-up and low dynamic compression set. The saponified rubber blend with styrene butadiene rubber (SBR) according to the recipe of rubber tire showed also a good performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Reinforcement and antioxidation effects of fullerenol-containing natural rubberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Hiroaki Kondo Abstract Natural rubber (NR) containing fullerenol, C60-OH, was prepared by two methods; one by mixing C60-OH aqueous solution to NR latex followed by coagulation (wet method) and the other by mixing C60-OH powder with solid rubber by an open roll mixer (dry method). C60-OH mixed by wet method was homogeneously dispersed in the rubber, while one mixed by dry method was particles in the size up to 70 ,m. The former exhibited large reinforcing and antiaging effect than the latter. The large antiaging effect was explained by the finding that C60-OH had large radical scavenging ability and gel forming ability during heat treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Properties of styrene-methyl methacrylate grafted DPNR latex at different monomer concentrationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Siti Hajjar Che Man Abstract The graft copolymerization of styrene and methyl methacrylate (MMA) on to deproteinized natural rubber (DPNR) latex was carried out. The effect of monomer concentrations on grafting efficiency, thermal and mechanical properties was studied. The synthesized graft copolymers were characterized by proton nuclear magnetic resonance (1H NMR) and the highest grafting efficiency was found at 20 wt % monomer concentration. At low monomer concentration (10 wt %) the grafting was not significant and at 30 wt %, the grafting efficiency was slightly decreased. The thermal properties of graft copolymers were analyzed using differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The degradation temperature (Tdeg) of the graft copolymer was increased with the increase in monomer concentration which indicates the improvement in thermal stability. The DSC result showed improvement in miscibility between the components as the monomer concentration increased. The mechanical properties of gum and filled modified NR were also investigated in terms of tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break decreased with an increase in monomer concentration while tensile modulus increased as the monomer concentration increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effects of quasi-nanogel particles on the rheological and mechanical properties of natural rubber: A new insightJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Suman Mitra Abstract The influence of sulfur-crosslinked, quasi-nanosized gels on the rheological and mechanical properties of raw natural rubber (NR) was investigated. Latex gels with different crosslink densities were prepared through the variation of the sulfur-to-accelerator ratio. These gels were characterized by dynamic light scattering, solvent swelling, and mechanical properties. The gels were mixed with raw NR latex at concentrations of 2, 4, 8, and 16 phr, and their effect on the rheological properties of NR was studied by Monsanto processability tester. The presence of gel in raw NR reduced the apparent shear viscosity and die swell considerably. Initially, the viscosity decreased up to a 8 phr gel loading and then increased with an increase in the gel loading. However, the change in the viscosity was related to the crosslink density of the gels. A new empirical equation relating the viscosity, volume fraction of the gels, and crosslink density was proposed. The die swell of gel-filled raw NR was at least 10% lower than that of unfilled raw NR and decreased with an increase in the gel loading. The effect of the gels on the die swell properties was explained through the calculation of the principal normal stress difference of gel-filled NR systems. Scanning electron photomicrographs of the extrudates revealed much better surface smoothness for the gel-filled virgin rubber systems than for the unfilled rubber. The addition of the gels to raw NR increased the modulus and tensile strength, whereas the elongation at break decreased. The effect of the gels on the dynamic mechanical properties of NR was also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | ||||||||||||||||||||||||||||||||||