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Sample records for sample latex math

  1. More math into Latex

    CERN Document Server

    Grätzer, George

    2007-01-01

    For close to two decades, Math into Latex has been the standard introduction and complete reference for writing articles and books containing mathematical formulas. In this fourth edition, the reader is provided with important updates on articles and books. An important new topic is discussed: transparencies (computer projections). Key features of More Math into Latex, 4th edition: Installation instructions for PC and Mac users; An example-based, visual approach and a gentle introduction with the Short Course; A detailed exposition of multiline math formulas with a Visual Guide; A unified appr

  2. 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 (pnitrile may be a viable alternative to latex in glove juice sampling methods, since nitrile avoids the risk of latex exposure.

  3. Nitrile versus Latex for Glove Juice Sampling.

    Directory of Open Access Journals (Sweden)

    Timothy F Landers

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

  4. 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.

  5. A Reappraisal of Online Mathematics Teaching Using LaTeX

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    Eamon Costello

    2009-12-01

    Full Text Available The mathematics language LaTeX is often seen outside of academic circles as a legacy technology that is awkward to use. MathML - a verbose language designed for data-exchange, and to be written and understood by machines - is sometimes by contrast seen as something that will aid online mathematics and lack of browser support for it bemoaned. However LaTeX can already do many of the things that MathML might promise. LaTeX is here proposed as a language from which small fragments, with concise syntax, can be used by people to easily create and share mathematical expressions online. The capability to embed fragments of LaTeX code in online discussions is described here and its impact on a group of educators and learners evaluated. Here LaTeX is posited as a useful tool for facilitating asynchronous, online, collaborative learning of mathematics.

  6. Effect of rootstock on the scion of Hevea brasiliensis through metabolic analysis of latex samples by 1H NMR

    Directory of Open Access Journals (Sweden)

    Eduardo Sanches Pereira do Nascimento

    2011-01-01

    Full Text Available In this study, the effect of rootstock on grafting through metabolomic analysis of latex (Hevea brasiliensis samples was verified by 1H nuclear magnetic resonance (NMR and multivariate data analysis. Sixteen metabolites present in the latex cytosol were characterized by NMR. PCA analysis showed that the latex samples of the RR and GR groups can be differentiated. The GR group samples present a metabolic profile similar to the RR group samples, while the RG group is in an intermediate position between RR and GG groups. Sucrose and formate contributed greatly to the separation obtained by PCA, presenting a good correlation between the results. 1H NMR was an efficient technique to differentiate latex samples from different types of rootstocks and grafting and in the future could be used to predict rubber production by latex analysis.

  7. 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

  8. 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.

  9. 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.

  10. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  12. Is Math Anxiety Always Bad for Math Learning? The Role of Math Motivation.

    Science.gov (United States)

    Wang, Zhe; Lukowski, Sarah L; Hart, Sara A; Lyons, Ian M; Thompson, Lee A; Kovas, Yulia; Mazzocco, Michèle M M; Plomin, Robert; Petrill, Stephen A

    2015-12-01

    The linear relations between math anxiety and math cognition have been frequently studied. However, the relations between anxiety and performance on complex cognitive tasks have been repeatedly demonstrated to follow a curvilinear fashion. In the current studies, we aimed to address the lack of attention given to the possibility of such complex interplay between emotion and cognition in the math-learning literature by exploring the relations among math anxiety, math motivation, and math cognition. In two samples-young adolescent twins and adult college students-results showed inverted-U relations between math anxiety and math performance in participants with high intrinsic math motivation and modest negative associations between math anxiety and math performance in participants with low intrinsic math motivation. However, this pattern was not observed in tasks assessing participants' nonsymbolic and symbolic number-estimation ability. These findings may help advance the understanding of mathematics-learning processes and provide important insights for treatment programs that target improving mathematics-learning experiences and mathematical skills. © The Author(s) 2015.

  13. Latex allergy in health care

    Directory of Open Access Journals (Sweden)

    Tina Virtič

    2012-11-01

    Full Text Available The increasing use of natural rubber latex medical gloves in the last three decades has caused an increase in latex allergy. The majority of risk groups for allergy development include health care workers, workers in the rubber industry, atopic individuals and children with congenital malformations. Three types of pathological reactions can occur in people using latex medical gloves: irritant contact dermatitis, allergic contact dermatitis and immediate hypersensitivity. The latex allergy is caused by constituent components of latex gloves and added powders; there are also numerous latex allergens involved in cross-reactivity between latex and fruits and vegetables, the so-called latex-fruit syndrome. The diagnosis is based on an accurate history of exposure, clinical presentation and confirmatory in vivo and in vitro tests. Prevention is the easiest, most effective and least expensive way to avoid latex allergy. Powder-free latex gloves with reduced levels of proteins and chemicals, and synthetic gloves for allergic workers must be provided in the work environment. There are already many health care institutions around the world where all latex products have been replaced by synthetic material products.

  14. Language, reading, and math learning profiles in an epidemiological sample of school age children.

    Science.gov (United States)

    Archibald, Lisa M D; Oram Cardy, Janis; Joanisse, Marc F; Ansari, Daniel

    2013-01-01

    Dyscalculia, dyslexia, and specific language impairment (SLI) are relatively specific developmental learning disabilities in math, reading, and oral language, respectively, that occur in the context of average intellectual capacity and adequate environmental opportunities. Past research has been dominated by studies focused on single impairments despite the widespread recognition that overlapping and comorbid deficits are common. The present study took an epidemiological approach to study the learning profiles of a large school age sample in language, reading, and math. Both general learning profiles reflecting good or poor performance across measures and specific learning profiles involving either weak language, weak reading, weak math, or weak math and reading were observed. These latter four profiles characterized 70% of children with some evidence of a learning disability. Low scores in phonological short-term memory characterized clusters with a language-based weakness whereas low or variable phonological awareness was associated with the reading (but not language-based) weaknesses. The low math only group did not show these phonological deficits. These findings may suggest different etiologies for language-based deficits in language, reading, and math, reading-related impairments in reading and math, and isolated math disabilities.

  15. Language, reading, and math learning profiles in an epidemiological sample of school age children.

    Directory of Open Access Journals (Sweden)

    Lisa M D Archibald

    Full Text Available Dyscalculia, dyslexia, and specific language impairment (SLI are relatively specific developmental learning disabilities in math, reading, and oral language, respectively, that occur in the context of average intellectual capacity and adequate environmental opportunities. Past research has been dominated by studies focused on single impairments despite the widespread recognition that overlapping and comorbid deficits are common. The present study took an epidemiological approach to study the learning profiles of a large school age sample in language, reading, and math. Both general learning profiles reflecting good or poor performance across measures and specific learning profiles involving either weak language, weak reading, weak math, or weak math and reading were observed. These latter four profiles characterized 70% of children with some evidence of a learning disability. Low scores in phonological short-term memory characterized clusters with a language-based weakness whereas low or variable phonological awareness was associated with the reading (but not language-based weaknesses. The low math only group did not show these phonological deficits. These findings may suggest different etiologies for language-based deficits in language, reading, and math, reading-related impairments in reading and math, and isolated math disabilities.

  16. Is Mathematical Anxiety Always Bad for Math Learning: The Role of Math Motivation

    Science.gov (United States)

    Wang, Zhe; Lukowski, Sarah L.; Hart, Sara Ann; Lyons, Ian M.; Thompson, Lee A.; Kovas, Yulia; Mazzocco, Michèle M.; Plomin, Robert; Petrill, Stephen A.

    2015-01-01

    The linear relations between math anxiety and math cognition have been frequently studied. However, the relations between anxiety and performance on complex cognitive tasks have been repeatedly demonstrated to follow a curvilinear fashion. Given the lack of attention to the possibility of such complex interplay between emotion and cognition in the math learning literature, the current study aimed to address this gap via exploring the relations between math anxiety, math motivation, and math cognition. The current study consisted of two samples. One sample included 262 pairs of young adolescent twins and the other included 237 adult college students. Participants self-reported their math anxiety and math motivation. Math cognition was assessed using a comprehensive battery of mathematics tasks. In both samples, results showed inverted-U relations between math anxiety and math performance in students with high intrinsic math motivation, and modest negative associations between math anxiety and math performance in students with low intrinsic math motivation. However, this pattern was not observed in tasks assessing student’s nonsymbolic and symbolic number estimation. These findings may help advance our understanding of mathematics learning processes and may provide important insights for treatment programs that target improving mathematics learning experiences and mathematical skills. PMID:26518438

  17. 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

  18. 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, ...

  19. PS-HEMA latex fractionation by sedimentation and colloidal crystallization

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    Cardoso André H.

    1999-01-01

    Full Text Available A poly(styrene-co-hydroxyethylmethacrylate latex underwent sedimentation under gravity followed by an spontaneous and extensive colloidal crystallization. It was then fractionated in three visually distinguishable layers. Latex aliquots layers were sampled at different heigths and the particles were characterized by PCS, microelectrophoresis, infrared spectra and analytical electron microscopy. The major fraction was opalescent and contained the colloidal crystals settled in the bottom of the liquid. Two other latex fractions were obtained, which differed in their chemical compositions, particle sizes and topochemical features from the self-arraying particles. Macrocrystallization of the fractionated latex yielded high quality crystals with a low frequency of defects, which confirms that particle chemical homogeneity is an important factor for particle self-arraying.

  20. Latex allergy in the workplace.

    Science.gov (United States)

    Toraason, M; Sussman, G; Biagini, R; Meade, J; Beezhold, D; Germolec, D

    2000-11-01

    While less than 1% of the general population is sensitized to latex, the U.S. Occupational Safety and Health Administration estimates that 8-12% of health-care workers are sensitized. The major source of workplace exposure is powdered natural rubber latex (NRL) gloves. NRL is harvested from HEVEA: brasiliensis trees and ammoniated to prevent coagulation resulting in the hydrolysis of the latex proteins. Prior to use in manufacturing, the latex is formulated by the addition of multiple chemicals. Thus, human exposure is to a mixture of residual chemicals and hydrolyzed latex peptides. Clinical manifestations include irritant contact dermatitis, allergic contact dermatitis (type IV), and type I immediate hypersensitivity response. Type I (IgE-mediated) NRL allergy includes contact urticaria, systemic urticaria, angioedema, rhinitis, conjunctivitis, bronchospasm, and anaphylaxis. Taking an accurate history, including questions on atopic status, food allergy, and possible reactions to latex devices makes diagnosis of type-I latex allergy possible. To confirm a diagnosis, either in vivo skin prick testing (SPT) or in vitro assays for latex-specific IgE are performed. While the SPT is regarded as a primary confirmatory test for IgE-mediated disease, the absence of a U.S. Food and Drug Administration-licensed HEVEA: brasiliensis latex extract has restricted its use in diagnosis. Serological tests have, therefore, become critically important as alternative diagnostic tests. Three manufacturers currently have FDA clearance for in vitro tests, to detect NRL-specific IgE. The commercially available assays may disagree on the antibody status of an individual serum, which may be due to the assay's detecting anti-NRL IgEs to different allergenic NRL proteins. Sensitized individuals produce specific IgE antibody to at least 10 potent HEVEA: allergens, Hev b 1-Hev b 10, each of which differs in its structure, size, and net charge. The relative content and ratios of Hevs in the

  1. [Prevention of adverse effects in latex allergic patients: organizing a latex safe operating theatre].

    Science.gov (United States)

    Bonalumi, Sabrina; Barbonaglia, Patrizia; Bertocchi, Carmen

    2006-01-01

    In 2001 the General Health Direction of Region Lombardia approved (decree n. 22303) a guideline for the prevention of latex allergic reactions in patients and health care workers. This document provides general recommendations in order to standardize behaviors in regional health care facilities. The reason is due to a rise in the incident of reactions to latex products in the last 20 years. Nowadays the prevalence is higher in certain risk groups (subjected to frequent and repeated exposures) rather than the general population. The aim of the project was to organize a latex safe operating theatre in the Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena of Milan (Fondazione) and to standardize behaviors in order to prevent adverse effects in latex allergic patients. Thanks to the literature review and the creation of a multidisciplinar team, we produced a protocol. Therefore, we requested manufacturers the certification of the latex content of their products. Results and conclusion. When latex allergic patients need to undergone surgery in our hospital, a latex safe operating theatre is organized by personnel following a multidisciplinar protocol. No allergic reactions were experienced during surgical procedures after the creation of an environment as free as possible from latex contamination. The project will involve an emergency room, one room or more of a ward and of the outpatients department.

  2. Parents' Beliefs about Children's Math Development and Children's Participation in Math Activities

    OpenAIRE

    Susan Sonnenschein; Claudia Galindo; Shari R. Metzger; Joy A. Thompson; Hui Chih Huang; Heather Lewis

    2012-01-01

    This study explored associations between parents’ beliefs about children’s development and children’s reported math activities at home. Seventy-three parents were interviewed about the frequency of their children’s participation in a broad array of math activities, the importance of children doing math activities at home, how children learn math, parents’ role in their children’s math learning, and parents’ own math skills. Although the sample consisted of African Americans, Chinese, Latino, ...

  3. Transcript Profiling of Hevea brasiliensis during Latex Flow

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    Jinquan Chao

    2017-11-01

    Full Text Available Latex exploitation enhances latex regeneration in rubber trees. The latex exploitation-caused latex flow lasts from 10 min to a few hours, which is convenient for exploring the transcript profiling of latex metabolism-related genes at the different stages of latex flow. In the present study, the expression pattern of 62 latex metabolism-related genes involved in water transportation, carbohydrate metabolism, natural rubber biosynthesis, hormone signaling, ROS generation and scavenging, and latex coagulum across three stages of latex flow between rubber tree clones CATAS7-33-97 and CATAS8-79 were comparatively analyzed by quantitative real-time PCR. The two clones show differences in latex regeneration and have a different duration of latex flow. The results showed that the expression levels of 38 genes were significantly higher in CATAS8-79 latex than in CATAS7-33-97 during latex regeneration, while 45 genes had a notably higher expression level in CATAS8-79 latex during latex flow. Together with the activation of the MEP pathway and jasmonate pathway in CATAS8-79 latex, HbPIP1;3, HbPIP1;4, HbSUT3, HbSus3, HbHMGS1-2, HbMK should contribute to the high latex regeneration ability. The up-regulation of ethylene signaling and Hb44KD and the down-regulation of latex coagulation-related genes in CATAS8-79 latex might contribute to its longer latex flow duration. This study provides some cues for revealing the regulation of latex metabolism in rubber trees.

  4. Latex allergy and filaggrin null mutations

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...... in the cases in this study may not have occurred through direct skin contact but through the respiratory organs via latex proteins that are absorbed in glove powder and aerosolized...

  5. Cream concentrated latex for foam rubber products

    Science.gov (United States)

    Suksup, R.; Imkaew, C.; Smitthipong, W.

    2017-12-01

    Fresh natural latex (around 40% rubber and 60% water) can be transformed to concentrated natural latex (around 60% rubber and 40% water) in order to realise economical transportation and easier latex product’s preparation. The concentrated natural latex is an extremely valuable material. It can be applied for many types of products, for example, foam rubber as pillow and mattress, elastic band, etc. Industrially, the concentrated natural latex can be prepared by centrifugation which requires an enormous expensive machine. From the eco-friendly products point of view, most of rubber entrepreneurs in the world try to develop a green rubber product. So, the main objective of this study is to prepare the cream concentrated latex without any sophisticated machine. Thus, we work on a simple, cheap and green method that does not use any expensive machine but uses water-based chemical as sodium alginate to prepare the cream concentrated latex. The optimal amount of sodium alginate in the latex was studied. The main characteristics of the cream concentrated latex were tested by various technics, such as alkalinity, total solid content (TSC), dry rubber content (DRC), etc. We found that there are no significant differences of results between fresh natural latex and cream concentrated latex, except for the TSC and DRC. The TSC and DRC of cream latex are higher than those of fresh natural latex. Finally, we propose a model of natural rubber particle and sodium alginate to form the cream concentrated latex.

  6. Anti-ulcer activity of Synadenium grantii latex

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    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.

  7. A Latent Profile Analysis of Math Achievement, Numerosity, and Math Anxiety in Twins

    Science.gov (United States)

    Hart, Sara A.; Logan, Jessica A. R.; Thompson, Lee; Kovas, Yulia; McLoughlin, Gráinne; Petrill, Stephen A.

    2016-01-01

    Underperformance in math is a problem with increasing prevalence, complex etiology, and severe repercussions. This study examined the etiological heterogeneity of math performance in a sample of 264 pairs of 12-year-old twins assessed on measures of math achievement, numerosity, and math anxiety. Latent profile analysis indicated 5 groupings of…

  8. Experimental investigation of the effect of latex solid/water ratio on latex modified co-matrix mechanical properties

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    Ahmed M. Diab

    2013-03-01

    Full Text Available Numerous researches were performed on latex modified concretes and associated properties, however; some vital factors were not given attention in previous works. This study focus on new factor which significantly affects the properties of latex modified cement paste, mortar or concrete. This factor is termed as ‘latex solid/water ratio’ which is defined herein as the ratio of weight of solid latex to weight of total water content of cement composite including the water in latex itself. The effect of this factor on some properties of cement paste, mortar and concrete were experimentally evaluated. Properties of cement paste include the produced calcium hydroxide and ettringite content during hydration process, while those of cement mortar take account of absorption and effect of temperature on compressive strength. Furthermore, the effect of this factor on the compressive and flexural strengths, modulus of elasticity, water penetration depth and drying shrinkage of concrete were explored. Based on experimental evidences, and spite of using different cement contents, sources of latex, water–cement ratios and slump values, it can be generally concluded that the latex solid/water ratio is a dominant factor affecting different properties of latex modified mortars and concrete.

  9. Latex sensitisation in healthcare workers in Singapore.

    Science.gov (United States)

    Tang, M B Y; Leow, Y H; Ng, V; Koh, D; Goh, C L

    2005-06-01

    Epidemiological data on latex sensitisation among Asian healthcare workers is lacking. The aim of the study is to determine the rate of latex sensitisation in our healthcare workers. We recruited 313 healthcare workers, of which 46.6% were operating theatre staff and 53.4% were non-operating theatre staff. Seventy-one administrative staff served as controls. All participants answered a self-administered questionnaire relating to latex exposure and glove-related symptoms. Latex sensitisation was determined by skin prick testing to latex and latex-specific IgE detection. The prevalence of latex sensitisation among healthcare workers was 9.6%, with no difference between operating theatre and nonoperating theatre staff. Glove-related symptoms were reported in 13.7% of all healthcare workers, of which 22.9% were sensitised to latex. Only 26.7% of latex-sensitised healthcare workers had glove-related symptoms while the rest were asymptomatic. The most common symptoms were itch and hand eczema but the most important discriminating symptom was contact urticaria. Personal history of atopy was more common in sensitised healthcare workers (40.0%) compared to non-sensitised workers (31.8%). Only 1 out of 9 (11.2%) symptomatic latex-sensitised subjects had sought previous medical attention for the problem. Latex sensitisation among healthcare workers in Singapore should be considered a significant occupational health risk, as it is in the West. Increased screening and awareness of this problem is essential to identify those at risk.

  10. Aspects of Degradability and Aging of Natural Rubber Latex Films Obtained by Induced Ionizing Radiation Processes of Latex Vulcanization

    International Nuclear Information System (INIS)

    Parra, D. F.

    2006-01-01

    This study refers to the degradability of NRLF, natural rubber latex films, obtained by ionizing radiation. Three types of NRLF were prepared: irradiated latex, irradiated latex with about 1% of soy lecithin and sulfur-vulcanized latex, by cold vulcanization process. The films were buried in vases of two different kinds of soil: common soil and common soil with earthworm humus. Fast aging tests in laboratory with exposition to ultraviolet rays were done in irradiated latex films and irradiated latex films with soy lecithin. The results obtained after ten months of tests with buried films agree with the results of the fast aging tests, showing singularities of each type of soil and each kind of latex process. It also shows how weather inclemency can induce the films degradation process. The sulfur-vulcanized films were weakly degraded when buried. The films with lecithin and buried in vase with only common soil showed the biggest mass loss, but the films with lecithin buried in vases with common earthworm humus and soil increased their weigh and dimensions due to fungi formation. The irradiated latex films are more degradable then the sulfur-vulcanized films. The irradiated latex film, unlike the sulfur vulcanized film, showed high fungi colonization when buried. We conclude that the irradiated latex films are more easily biodegradable than the sulfur vulcanized latex films. The biodegradability increases with the addition of small amounts of soy lecithin (∼1%). The mechanical resistance of the buried films decreased related to the non-buried ones, proving that the outdoor aging in soil and the presence of fungi in the films can modify the mechanical properties of the irradiated latex owing to the biodegradation

  11. Color Spectrum Properties of Pure and Non-Pure LATEX in Discriminating Rubber Clone Series

    International Nuclear Information System (INIS)

    Noor Aishah Khairuzzaman; Hadzli Hashim; Nina Korlina Madzhi; Noor Ezan Abdullah; Faridatul Aima Ismail; Ahmad Faiz Sampian; Azhana Fatnin Che Will

    2015-01-01

    A study of color spectrum properties for pure and non-pure latex in discriminating rubber clone series has been presented in this paper. There were five types of clones from the same series being used as samples in this study named RRIM2002, RRIM2007, RRIM2008, RRIM2014, and RRIM3001. The main objective is to identify the significant color spectrum (RGB) from pure and non-pure latex that can discriminate rubber clone series. The significant information of color spectrum properties for pure and non-pure latex is determined by using spectrometer and Statistical Package for the Social Science (SPSS). Visible light spectrum (VIS) is used as a radiation light of the spectrometer to emit light to the surface of the latex sample. By using SPSS software, the further numerical analysis of color spectrum properties is being conducted. As the conclusion, blue color spectrum for non-pure is able to discriminate for all rubber clone series whereas only certain color spectrum can differentiate several clone series for pure latex. (author)

  12. The Role of Parental Math Anxiety and Math Attitude in Their Children's Math Achievement

    Science.gov (United States)

    Soni, Akanksha; Kumari, Santha

    2017-01-01

    The present study investigated the antecedents and consequences of children's math anxiety and math attitude. A total of 595 students aged 10 to 15 years (5th to 10th grades) and 1 parent of each (mother or father) participated in the study. The study was conducted in India, with the study sample drawn from schools in South-West Punjab. Math…

  13. Early Math Interest and the Development of Math Skills

    Science.gov (United States)

    Fisher, Paige H.; Dobbs-Oates, Jennifer; Doctoroff, Greta L.; Arnold, David H.

    2012-01-01

    Prior models suggest that math attitudes and ability might strengthen each other over time in a reciprocal fashion (Ma, 1997). The current study investigated the relationship between math interest and skill both concurrently and over time in a preschool sample. Analyses of concurrent relationships indicated that high levels of interest were…

  14. 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.

  15. Natural rubber latex: determination and interpretation of flow curves

    Directory of Open Access Journals (Sweden)

    Harrison Lourenço Corrêa

    2015-08-01

    Full Text Available AbstractAs consumers become more demanding, the importance grows of guaranteeing the quality of products. The employment of reliable testing techniques that assure the origin and characteristics of the inputs used by industry is a key factor in this respect. In the rubber processing industry, the most commonly used characterization tests include determination of the total solids and dry rubber content, mechanical stability, odor, color and presence of volatile compounds, among others. For the most part, these tests are sufficient for the latex transformation industry. However, in situations where there is a need to know the behavior of latex in reaction to the mechanical forces of machines (mixers, pumps, etc., other tests must be used. Rheological tests to determine viscoelastic data by means of plotting flow curves combined with the application of theoretical models can provide important details for characterization of different types of latex. This article presents the protocol employed by the Rheology and Image Laboratory of Rio de Janeiro State University (UERJ for the rheological study of Brazilian latex. The samples analyzed came from the state of São Paulo.

  16. GRE math workbook

    CERN Document Server

    Madore, Blair

    2015-01-01

    Reflective of the current GRE, this third edition includes a description of the General Math Exam explaining structure, questions types, and scoring, strategies for problem solving, two full-length math sample sections structured to reflect the actual exam, answers thoroughly explained, and more.

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

    Science.gov (United States)

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

    1999-01-01

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

  18. Latex improvement of recycled asphalt pavement

    Science.gov (United States)

    Drennon, C.

    1982-08-01

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

  19. Cryo-SEM studies of latex/ceramic nanoparticle coating microstructure development.

    Science.gov (United States)

    Luo, Hui; Scriven, L E; Francis, Lorraine F

    2007-12-15

    Cryogenic scanning electron microscopy (cryo-SEM) was used to investigate microstructure development of composite coatings prepared from dispersions of antimony-doped tin oxide (ATO) nanoparticles (approximately 30 nm) or indium tin oxide (ITO) nanoparticles (approximately 40 nm) and latex particles (polydisperse, D(v): approximately 300 nm). Cryo-SEM images of ATO/latex dispersions as-frozen show small clusters of ATO and individual latex particles homogeneously distribute in a frozen water matrix. In contrast, cryo-SEM images of ITO/latex dispersions as-frozen show ITO particles adsorb onto latex particle surfaces. Electrostatic repulsion between negatively charged ATO and negatively charged latex particles stabilizes the ATO/latex dispersion, whereas in ITO/latex dispersion, positively charged ITO particles are attracted onto surfaces of negatively charged latex particles. These results are consistent with calculations of interaction potentials from past research. Cryo-SEM images of frozen and fractured coatings reveal that both ceramic nanoparticles and latex become more concentrated as drying proceeds; larger latex particles consolidate with ceramic nanoparticles in the interstitial spaces. With more drying, compaction flattens the latex-latex particle contacts and shrinks the voids between them. Thus, ceramic nanoparticles are forced to pack closely in the interstitial spaces, forming an interconnected network. Finally, latex particles partially coalesce at their flattened contacts, thereby yielding a coherent coating. The research reveals how nanoparticles segregate and interconnect among latex particles during drying.

  20. 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.

  1. Gender compatibility, math-gender stereotypes, and self-concepts in math and physics

    Science.gov (United States)

    Koul, Ravinder; Lerdpornkulrat, Thanita; Poondej, Chanut

    2016-12-01

    [This paper is part of the Focused Collection on Gender in Physics.] Positive self-assessment of ability in the quantitative domains is considered critical for student participation in science, technology, engineering, and mathematics field studies. The present study investigated associations of gender compatibility (gender typicality and contentedness) and math-gender stereotypes with self-concepts in math and physics. Statistical analysis of survey data was based on a sample of 170 male and female high school science students matched on propensity scores based on age and past GPA scores in math. Results of MANCOVA analyses indicated that the combination of high personal gender compatibility with low endorsement of math-gender stereotypes was associated with low gender differentials in math and physics self-concepts whereas the combination of high personal gender compatibility with high endorsement of math-gender stereotypes was associated with high gender differentials in math and physics self-concepts. These results contribute to the recent theoretical and empirical work on antecedents to the math and physics identities critical to achieving gender equity in STEM fields.

  2. Prevalence of manufacturing defects in latex examination gloves used in selected dental practices in central Saudi Arabia.

    Science.gov (United States)

    Al-Swuailem, Abdullah S

    2014-07-01

    To assess the defect rates in latex examination gloves used in selected dental practices in Riyadh, Saudi Arabia. In this cross-sectional study, a total of 796 latex examination gloves were collected from 5 governmental hospitals and 5 private dental practices between April 2012 and May 2012. The gloves were assessed for presence of defects visually (VT) and using water inflation test (WIT). One and 2 sample t-tests were used to assess significant differences in defect rates among each latex brand, and between governmental hospitals and private dental practices. Defects in latex gloves were more likely to be identified using WIT compared with VT (20.2% versus 4.3%, p=0.000). Using WIT, examined latex gloves had a defect rate approximately 8 times the acceptable quality level of 2.5% (20.2%, p=0.000). Using WIT, gloves used in private dental practices had significantly higher defect rates compared with governmental dental clinics (25.6% versus 14.6%, p=0.006). Most latex examination gloves used in the sampled governmental dental clinics and private dental practices in Riyadh had significantly higher preexisting defect rates than acceptable standard levels.

  3. Exploiting epoxidized natural rubber latex (ENRL) as a starting raw material for latex-based products

    Science.gov (United States)

    Siti Nor Qamarina, M.; Fatimah Rubaizah, M. R.; Nurul Suhaira, A.; Norhanifah, M. Y.

    2017-12-01

    Epoxidized natural rubber latex (ENRL) is a chemically modified natural rubber latex produced from epoxidation process that involves usage of organic peracids. Conversion of the ENRL into dry rubber products has been known to exhibit many beneficial properties, however limited published works were found on diversifiying the ENRL latex-based products applications. In this preliminary work, different source of raw materials and neutralization systems were investigated. The objective was to explore possibilities in producing distinctive ENRL. Findings have demonstrated that different source of raw materials and neutralization systems influenced the typical ENRL specifications, stability behavior and particle size distribution. Morphological observations performed on these ENRL systems appeared to agree with the ENRL characteristics achieved. Since experimenting these two main factors resulted in encouraging ENRL findings, detailed work shall be further scrutinized to search for an optimum condition in producing marketable ENRL specifically for latex-based products applications.

  4. Radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    Wan Manshol bin Wan Zin; Norjanah binti Mohid

    1994-01-01

    This paper describes the experimental techniques and the results of radiation vulcanization of natural rubber latex carried out on several high ammonia latices available in the country. The efficiency of various sensitisers and stabilisers used were evaluated in terms of the gamma radiation dose required to produce the maximum tensile strengths. The extent of crosslinking of RVNRL sample films were estimated by equilibrium swelling ratio measurements. The stability of pre-irradiated and post-irradiated samples were monitored using viscosity measurements as the parameter

  5. Analysis of Aqueous Extractable Protein in Radiation Pre vulcanized Natural Rubber Latex (RVNRL) And Sulphur Pre vulcanized Natural Rubber Latex (SVNRL)

    International Nuclear Information System (INIS)

    Sofian Ibrahim; Mohd Noor Wadi Mat Lazim; Syuhada Ramli; Keong, C.C.; Khairul Hisyam Mohd Yusof; Muhammad Saiful Omar; Najib Mohd Zakey; Hafizuddin Maseri; Noor Hasni Mohd Ali

    2015-01-01

    The use of radiation do not only produces Radiation Pre vulcanized Natural Rubber Latex (RVNRL) that can be used for the production of nitrosamines free products, moreover, RVNRL also able to exclude type IV allergy that caused by high protein content in the products. Leaching water from production of finger coat from RVNRL and Sulphur Pre vulcanized Natural rubber Latex (SVNRL) has been collected. Extractable protein content from water samples measured according to the test protocol ASTM D5712-2010. Water from leaching process of finger coat made from RVNRL showed a higher protein content than SVNRL. This explains why RVNRL based products contain very low protein content and thus reduce the risk of Type IV allergy. (author)

  6. Emotion with tears decreases allergic responses to latex in atopic eczema patients with latex allergy.

    Science.gov (United States)

    Kimata, Hajime

    2006-07-01

    Allergic responses are enhanced by stress, whereas they are reduced by laughter in atopic eczema patients. Emotion with tears decreases plasma IL-6 levels in patients with rheumatoid arthritis. Thus, the effect of emotion with tears on allergic responses in patients with atopic eczema was studied. Sixty patients with atopic eczema having latex allergy viewed both the weather information video and the heart-warming movie, Kramer vs. Kramer. Just before and immediately after viewing each video, allergic responses to latex were measured. Viewing the weather information video did not cause emotion with tears in any patients, and it failed to modulate allergic responses. In contrast, viewing Kramer vs. Kramer caused emotion with tears in 44 of 60 patients, and it reduced allergic skin wheal responses to latex and latex-specific IgE production in them. Emotion with tears reduced allergic responses, and it may be useful in the treatment of allergic diseases.

  7. Experimental study on the drying of natural latex medical gloves

    Science.gov (United States)

    Chankrachang, Mano; Yongyingsakthavorn, Pisit; Tohsan, Atitaya; Nontakaew, Udomkiat

    2018-01-01

    The purpose of this research was to study latex film drying at 70 °C using a laboratory drying oven. Two different total solid content (TSC) latex compounds, which 45% TSC and 35% TSC were used. The undried latex films were prepared according to the common procedures used in latex gloves manufacturers, that is, by dry coagulant dipping process. The experimental results such as initial moisture content, the amount of moisture and drying time of latex films in each latex compound formula were determined. After that, the results were projected to calculate on the production capacity expand by 1 million piece/day of natural latex medical gloves. Finally, the rate of moisture entering the latex drying oven and the energy consumption of the drying oven were estimated. The results indicated that when the 35% TSC of latex compound was used. The initial moisture content of latex film was higher than 45% TSC of latex compound about 7%. The drying time of 35% TSC was longer than 45% TSC for 2.5 min and consume more energy about 10%. As a result, the 45% TSC latex compound was the better way to saving energy and managing humidity in the production line. Therefore, it was found to very useful to an approximate design length and size of actual of latex drying oven and the rate of moisture entering the oven as well.

  8. Extractable proteins from electron beam (EB) irradiated natural rubber (NR) latex

    International Nuclear Information System (INIS)

    Feroza Akhtar; Fumio Yoshii; Keizo Makuuchi

    1996-01-01

    The protein assay of natural rubber latex (NRL) vulcanized by low energy electron beam (EB, 300 keV, 30 mA) has been carried out using Bicinchoninic acid (BCA) reagent. Extractable protein in irradiated latex film was determined by measuring the absorption of colored solution at 562 nm using UV spectrometer. The effect of various radiation doses on the extractable protein content of NRL was investigated. It was ,found that the quantities of extractable protein increases with radiation dose. When compared with ,gamma-ray irradiated samples the same trend was observed. Electron beam irradiated latex films are leached in 1% (ammonia water for various lengths of time. From the results it was established that within 2 hours of leaching in ammonia water most of the extractable protein (96%) were removed from rubber film

  9. Math practice and its influence on math skills and executive functions in adolescents with mild to borderline intellectual disability.

    Science.gov (United States)

    Jansen, Brenda R J; De Lange, Eva; Van der Molen, Mariët J

    2013-05-01

    Adolescents with mild to borderline intellectual disability (MBID) often complete schooling without mastering basic math skills, even though basic math is essential for math-related challenges in everyday life. Limited attention to cognitive skills and low executive functioning (EF) may cause this delay. We aimed to improve math skills in an MBID-sample using computerized math training. Also, it was investigated whether EF and math performance were related and whether computerized math training had beneficial effects on EF. The sample consisted of a total of 58 adolescents (12-15 years) from special education. Participants were randomly assigned to either the experimental group or a treatment as usual (TAU) group. In the experimental condition, participants received 5 weeks of training. Math performance and EF were assessed before and after the training period. Math performance improved equally in both groups. However, frequently practicing participants improved more than participants in the control group. Visuo-spatial memory skills were positively related to addition and subtraction skills. Transfer effects from math training to EF were absent. It is concluded that math skills may increase if a reasonable effort in practicing math skills is made. The relation between visuo-spatial memory skills provides opportunities for improving math performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. 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

  11. Cement-latex grouting mortar for cementing boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Kateev, I S; Golyshkina, L A; Gorbunova, I V; Kurochkin, B M; Vakula, Ya V

    1980-01-01

    The need for the development of cement-latex grouting mortar for the purpose of separating strata when reinforcing boreholes at deposits in the Tatar Associated SSR is evaluated. Results of studies of the physical and mechanical properties of cement-latex grouting mortar systems (mortar plus brick) are presented. Formulas for preparing cement-latex grouting mortor are evaluated and results of industrial tests of such mortars shown.

  12. Parent-child math anxiety and math-gender stereotypes predict adolescents' math education outcomes.

    Science.gov (United States)

    Casad, Bettina J; Hale, Patricia; Wachs, Faye L

    2015-01-01

    Two studies examined social determinants of adolescents' math anxiety including parents' own math anxiety and children's endorsement of math-gender stereotypes. In Study 1, parent-child dyads were surveyed and the interaction between parent and child math anxiety was examined, with an eye to same- and other-gender dyads. Results indicate that parent's math anxiety interacts with daughters' and sons' anxiety to predict math self-efficacy, GPA, behavioral intentions, math attitudes, and math devaluing. Parents with lower math anxiety showed a positive relationship to children's math outcomes when children also had lower anxiety. The strongest relationships were found with same-gender dyads, particularly Mother-Daughter dyads. Study 2 showed that endorsement of math-gender stereotypes predicts math anxiety (and not vice versa) for performance beliefs and outcomes (self-efficacy and GPA). Further, math anxiety fully mediated the relationship between gender stereotypes and math self-efficacy for girls and boys, and for boys with GPA. These findings address gaps in the literature on the role of parents' math anxiety in the effects of children's math anxiety and math anxiety as a mechanism affecting performance. Results have implications for interventions on parents' math anxiety and dispelling gender stereotypes in math classrooms.

  13. 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.

  14. 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

  15. Parent-child math anxiety and math-gender stereotypes predict adolescents' math education outcomes

    Science.gov (United States)

    Casad, Bettina J.; Hale, Patricia; Wachs, Faye L.

    2015-01-01

    Two studies examined social determinants of adolescents' math anxiety including parents' own math anxiety and children's endorsement of math-gender stereotypes. In Study 1, parent-child dyads were surveyed and the interaction between parent and child math anxiety was examined, with an eye to same- and other-gender dyads. Results indicate that parent's math anxiety interacts with daughters' and sons' anxiety to predict math self-efficacy, GPA, behavioral intentions, math attitudes, and math devaluing. Parents with lower math anxiety showed a positive relationship to children's math outcomes when children also had lower anxiety. The strongest relationships were found with same-gender dyads, particularly Mother-Daughter dyads. Study 2 showed that endorsement of math-gender stereotypes predicts math anxiety (and not vice versa) for performance beliefs and outcomes (self-efficacy and GPA). Further, math anxiety fully mediated the relationship between gender stereotypes and math self-efficacy for girls and boys, and for boys with GPA. These findings address gaps in the literature on the role of parents' math anxiety in the effects of children's math anxiety and math anxiety as a mechanism affecting performance. Results have implications for interventions on parents' math anxiety and dispelling gender stereotypes in math classrooms. PMID:26579000

  16. Parent-Child Math Anxiety and Math-Gender Stereotypes Predict Adolescents’ Math Education Outcomes

    Directory of Open Access Journals (Sweden)

    Bettina J Casad

    2015-11-01

    Full Text Available Two studies examined social determinants of adolescents’ math anxiety including parents’ own math anxiety and children’s endorsement of math-gender stereotypes. In study 1, parent-child dyads were surveyed and the interaction between parent and child math anxiety was examined, with an eye to same- and other-gender dyads. Results indicate that parent’s math anxiety interacts with daughters’ and sons’ anxiety to predict math self-efficacy, GPA, behavioral intentions, math attitudes, and math devaluing. Parents with lower math anxiety showed a positive relationship to children’s math outcomes when children also had lower anxiety. The strongest relationships were found with same-gender dyads, particularly Mother-Daughter dyads. Study 2 showed that endorsement of math-gender stereotypes predicts math anxiety (and not vice versa for performance beliefs and outcomes (self-efficacy and GPA. Further, math anxiety fully mediated the relationship between gender stereotypes and math self-efficacy for girls and for boys, and for boys with GPA. These findings address gaps in the literature on the role of parents’ math anxiety in the effects of children’s math anxiety and math anxiety as a mechanism affecting performance. Results have implications for interventions on parents’ math anxiety and dispelling gender stereotypes in math classrooms.

  17. Working memory, math performance, and math anxiety.

    Science.gov (United States)

    Ashcraft, Mark H; Krause, Jeremy A

    2007-04-01

    The cognitive literature now shows how critically math performance depends on working memory, for any form of arithmetic and math that involves processes beyond simple memory retrieval. The psychometric literature is also very clear on the global consequences of mathematics anxiety. People who are highly math anxious avoid math: They avoid elective coursework in math, both in high school and college, they avoid college majors that emphasize math, and they avoid career paths that involve math. We go beyond these psychometric relationships to examine the cognitive consequences of math anxiety. We show how performance on a standardized math achievement test varies as a function of math anxiety, and that math anxiety compromises the functioning of working memory. High math anxiety works much like a dual task setting: Preoccupation with one's math fears and anxieties functions like a resource-demanding secondary task. We comment on developmental and educational factors related to math and working memory, and on factors that may contribute to the development of math anxiety.

  18. Laboratory evaluation of a simple and rapid latex agglutination assay for the serodiagnosis of typhoid fever

    NARCIS (Netherlands)

    Abdoel, Theresia H.; Pastoor, Rob; Smits, Henk L.; Hatta, Mochammad

    2007-01-01

    A latex agglutination assay for the serodiagnosis of typhoid fever was evaluated on samples collected from patients with clinical suspicion of typhoid fever in South Sulawesi, Indonesia, where the disease is endemic. The latex assay is very easy to use, gives a rapid result and may be used as a

  19. Synthesis and characterization of novel polyacid-stabilized latexes.

    Science.gov (United States)

    Yang, Pengcheng; Armes, S P

    2012-09-18

    A series of novel polyacid macromonomers based on 2-hydroxypropyl methacrylate (HPMA) were prepared by atom transfer radical polymerization (ATRP) via a two-step route. First, a range of well-defined PHPMA homopolymer precursors were synthesized by ATRP using a tertiary amine-functionalized initiator, 2-(dimethylamino)ethyl-2-bromoisobutyrylamide, and a CuCl/2, 2'-bipyridine (bpy) catalyst in alcoholic media at 50 °C. ATRP polymerizations were relatively slow and poorly controlled in pure isopropanol (IPA), especially when targeting higher degrees of polymerization (DP > 30). Improved control was achieved by addition of water: low polydispersity (M(w)/M(n) propyl methacrylate) (PSPMA) macromonomers by quaternizing the tertiary amine end-group with excess 4-vinylbenzyl chloride, followed by esterification of the pendent hydroxyl groups using excess succinic anhydride at 20 °C. These polyacid macromonomers were evaluated as reactive steric stabilizers for polystyrene latex synthesis under either aqueous emulsion polymerization or alcoholic dispersion polymerization conditions. Near-monodisperse polystyrene latexes were obtained via aqueous emulsion polymerization using 10 wt % PSPMA macromonomer (with respect to styrene monomer) with various initiators as evidenced by scanning electron microscopy, disk centrifuge photosedimentometry and light scattering studies. PSPMA macromomer concentrations as low as 1.0 wt % also produced near-monodisperse latexes, suggesting that these PSPMA macromonomers are highly effective stabilizers. Alcoholic dispersion polymerization of styrene conducted in various ethanol/water mixtures with 10 wt % PSPMA(50) macromonomer produced relatively large near-monodisperse latexes. Increasing the water content in such formulations led to smaller latexes, as expected. Control experiments conducted with 10 wt % PSPMA(50) homopolymer produced relatively large polydisperse latexes via emulsion polymerization and only macroscopic precipitates via

  20. Biodegradability and aging study of rubber films obtained by gamma radiation vulcanization processes of latex

    International Nuclear Information System (INIS)

    Martins, Carlos Felipe Pinto

    2005-01-01

    The natural rubber latex (NRL) is industrially crosslinked by the conventional process of vulcanization, which uses sulphur and heat. Otherwise, the network can also be done by the alternative process with ionizing radiation. In this work the crosslinking of NRL was studied by the comparison of the conventional vulcanization system and the ionizing radiation process of 60 C source. The products obtained, the irradiated latex, the irradiated latex with approximately 1% of soy lecithin and the sulphur vulcanized latex were tested by accelerated aging with ultraviolet (UV) and outdoor aging with compostage, tensile strength at break, swelling and gel fraction, fungi micro biota, scanning electron microscopy (SEM), infrared spectroscopy (FTIR) and thermogravimetry and differential scanning calorimetry analysis (TG and DSC). The results showed that the aging with microorganisms have a great influence in the physical properties of the samples. The thermal stability order observed showed that the sulphur vulcanized latex is more resistant, what is probably associated to a network more stable under the aging conditions. On the other hand, the irradiated latex showed intense biodegradation aspects, particularly with the presence of the soy lecithin. (author)

  1. The preparation of RVNRL using Malaysian-produced latexes

    International Nuclear Information System (INIS)

    Zin, W.M. bin W.; Mohid, N. bte; Hasan, J. bin; Noor, W.K.A. bte W.M.; Jaafar, Zulkifli

    1993-01-01

    This research project was carried out using latexes supplied by three of the suppliers in Malaysia. From the results of studies carried out in search of the best sensitiser for RVNRL preparation, the use of n-butyl acrylate (n-BA) as a sensitiser gave the most promising results. However, its use as a sensitiser is not universal to all latexes available in the country. The problem was overcome by using different formulations for different latexes. For the latex supplied by Golden Hope (Hytex), a combination of sensitisers i.e. n-BA plus 2-ethyl hexyl acrylate (2-EHA) with a 10% potassium hydroxide solution as the stabilizer, was required. Latex supplied by MARDEC (Matex), seemed to need only n-BA as the sensitiser. However, a stabilizer was still required and the use of a 10% KOH solution was found to be suitable. A large range of stabilizers and sensitisers were applicable to Guthrie latex. The use of n-BA as the sensitiser and potassium laurylic acid as the stabilizer seemed the most favourable formulation. All the results are discussed in the form of a correlation between dose and the tensile properties of RVNRL vulcanizates, equilibrium swelling ratio and standing time of the latex formulation. (author)

  2. Costs and return analysis in rubber latex production in Edo State ...

    African Journals Online (AJOL)

    The study examined the costs and return analysis in rubber latex production in Edo Sate, Nigeria. Multi-stage sampling method was adopted to select 96 smallholder rubber framers for the study. The first stage was a purposive sampling of two LGAs and then simple random sampling of 6 villages each from the two LGA.

  3. Parent-child math anxiety and math-gender stereotypes predict adolescents' math education outcomes

    OpenAIRE

    Casad, Bettina J.; Hale, Patricia; Wachs, Faye L.

    2015-01-01

    Two studies examined social determinants of adolescents’ math anxiety including parents’ own math anxiety and children’s endorsement of math-gender stereotypes. In study 1, parent-child dyads were surveyed and the interaction between parent and child math anxiety was examined, with an eye to same- and other-gender dyads. Results indicate that parent’s math anxiety interacts with daughters’ and sons’ anxiety to predict math self-efficacy, GPA, behavioral intentions, math attitudes, and math de...

  4. Plant latex lipase as biocatalysts for biodiesel production | Mazou ...

    African Journals Online (AJOL)

    Plant latex lipase as biocatalysts for biodiesel production. ... This paper provides an overview regarding the main aspects of latex, such as the reactions catalyzed, physiological functions, specificities, sources and their industrial applications. Keywords: Plant latex, lipase, Transesterification, purification, biodiesel ...

  5. Ten years incidence of natural rubber latex sensitization and symptoms in a prospective cohort of health care workers using non-powdered latex gloves 2000-2009.

    Science.gov (United States)

    Larese Filon, Francesca; Bochdanovits, Letizia; Capuzzo, Chiara; Cerchi, Roberto; Rui, Francesca

    2014-07-01

    To assess the incidence of sensitization and gloves-related symptoms in 10-year follow-up in a group of health care workers (9,660 person-years) using non-powdered latex gloves from 2000 to 2009 and to examine related factors. We studied 2,053 health care workers in Trieste Hospitals by means of skin prick test for latex extract, patch tests and medical examinations. We report the incidence of latex sensitization among workers using non-powdered latex gloves. The incidence of latex sensitization, rhinitis, asthma, urticaria, irritant and allergic contact dermatitis were 1.0; 0.12; 0.21; 0.72; 2.39 and 2.50 cases per 1,000 person-years, respectively. Respiratory symptoms and urticaria were positively related with latex sensitization (OR = 8.0; 95 % CL 1.27-48.6), with common allergic respiratory symptoms (OR = 4.19; 95 % CL 1.04-16.8) and with familial atopy (OR = 4.47; 95 % CL 1.1-17.9). The incidence of latex sensitization and latex-related symptoms were very low but subjects with allergic symptoms related to common allergens are at higher risk. The use of non-latex gloves is suggested for them.

  6. Talking Math, Blogging Math

    OpenAIRE

    Mathews, Linda Marie

    2009-01-01

    Talking Math, Blogging Math is a curriculum designed to aid middle school Pre- Algebra students' mathematical problem-solving through the use of academic language instruction, explanatory proofs, and online technology (blogging). Talking Math, Blogging Math was implemented over a period of ten weeks during the 2008 - 2009 school year. The school where the curriculum was implemented is a non-traditional classroom-based charter school. The 7th, 8th and 9th grade students attended class twice a ...

  7. Trajectories of Self-Perceived Math Ability, Utility Value and Interest across Middle School as Predictors of High School Math Performance

    Science.gov (United States)

    Petersen, Jennifer Lee; Hyde, Janet Shibley

    2017-01-01

    Although many studies have documented developmental change in mathematics motivation, little is known about how these trends predict math performance. A sample of 288 participants from the United States reported their perceived math ability, math utility value and math interest in 5th, 7th and 9th grades. Latent growth curve models estimated…

  8. Recombinant albumin monolayers on latex particles.

    Science.gov (United States)

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

    2014-01-14

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

  9. Math Anxiety Assessment with the Abbreviated Math Anxiety Scale: Applicability and usefulness: insights from the Polish adaptation

    Directory of Open Access Journals (Sweden)

    Krzysztof eCipora

    2015-11-01

    Full Text Available Math anxiety has an important impact on mathematical development and performance. However, although math anxiety is supposed to be a transcultural trait, assessment instruments are scarce and are validated mainly for Western cultures so far. Therefore, we aimed at examining the transcultural generality of math anxiety by a thorough investigation of the validity of math anxiety assessment in Eastern Europe. We investigated the validity and reliability of a Polish adaptation of the Abbreviated Math Anxiety Scale (AMAS, known to have very good psychometric characteristics in its original, American-English version as well as in its Italian and Iranian adaptations.We also observed high reliability, both for internal consistency and test-retest stability of the AMAS in the Polish sample. The results also show very good construct, convergent and discriminant validity: The factorial structure in Polish adult participants (n = 857 was very similar to the one previously found in other samples; AMAS scores correlated moderately in expected directions with state and trait anxiety, self-assessed math achievement and skill as well temperamental traits of emotional reactivity, briskness, endurance and perseverance. Average scores obtained by participants as well as gender differences and correlations with external measures were also similar across cultures. Beyond the cultural comparison, we used path model analyses to show that math anxiety relates to math grades and self-competence when controlling for trait anxiety.The current study shows transcultural validity of math anxiety assessment with the AMAS.

  10. Math Anxiety Assessment with the Abbreviated Math Anxiety Scale: Applicability and Usefulness: Insights from the Polish Adaptation.

    Science.gov (United States)

    Cipora, Krzysztof; Szczygieł, Monika; Willmes, Klaus; Nuerk, Hans-Christoph

    2015-01-01

    Math anxiety has an important impact on mathematical development and performance. However, although math anxiety is supposed to be a transcultural trait, assessment instruments are scarce and are validated mainly for Western cultures so far. Therefore, we aimed at examining the transcultural generality of math anxiety by a thorough investigation of the validity of math anxiety assessment in Eastern Europe. We investigated the validity and reliability of a Polish adaptation of the Abbreviated Math Anxiety Scale (AMAS), known to have very good psychometric characteristics in its original, American-English version as well as in its Italian and Iranian adaptations. We also observed high reliability, both for internal consistency and test-retest stability of the AMAS in the Polish sample. The results also show very good construct, convergent and discriminant validity: The factorial structure in Polish adult participants (n = 857) was very similar to the one previously found in other samples; AMAS scores correlated moderately in expected directions with state and trait anxiety, self-assessed math achievement and skill as well temperamental traits of emotional reactivity, briskness, endurance, and perseverance. Average scores obtained by participants as well as gender differences and correlations with external measures were also similar across cultures. Beyond the cultural comparison, we used path model analyses to show that math anxiety relates to math grades and self-competence when controlling for trait anxiety. The current study shows transcultural validity of math anxiety assessment with the AMAS.

  11. Effect of Amphiphilic Alkyl Chain Length Upon Purified LATEX Stability

    International Nuclear Information System (INIS)

    Amira Amir Hassan; Amir Hashim Mohd Yatim

    2015-01-01

    Rubber particles in purified latex (PL) are stabilized by a film of protein and fatty acid soap (surfactant). Saturated straight-chain fatty acid soaps can assist an enhancement of latex stability. However, whether the alkyl chain length plays an important role in increasing the stability is still an issue. The aim of this study is to investigate the effect of alkyl chain length of anionic surfactant on the stability of purified latex. The fatty acid soap of decanoate (9), laurate (11), sodium dodecyl sulphate (SDS) (12) and palmitate (15) were used. The numbers in parentheses indicating the number of carbon present in alkyl chain of the soap. The results showed that the impact of alkyl chain length on the stability of latex is in the order of laurate > decanoate > SDS > palmitate > purified latex accordingly. The alkyl chain length does giving a significant effect on latex stability after longer stirring time. The particle size of latex with the presence of surfactant is greater compare to a single particle itself due to extension of particles diameter. Thus suitable interaction of the nonpolar tail of surfactant with the hydrophobic regions of latex surface played a major role in maintaining a stable latex system. (author)

  12. 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.

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

    Science.gov (United States)

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

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

  14. Isolation and characterization of latex-specific promoters from Papaver somniferum L.

    OpenAIRE

    Raymond, Michelle Jean

    2004-01-01

    The pharmacologically important alkaloids morphine and codeine are found in latex of opium poppy (Papaver somniferum). Latex is harbored in laticifers, a specialized vascular cell-type. Isolation and characterization of latex-specific genes may provide a useful tool to metabolically engineer increased alkaloid production. Previous research in the Nessler laboratory identified genes that exhibit latex-specific gene expression. Latex-specific genes were an 2-oxoglutarate-dioxygense (DIOX), ...

  15. Biodegradability and aging study of rubber films obtained by gamma radiation vulcanization processes of latex; Estudo da biodegradabilidade e envelhecimento de filmes de borracha obtidos por processos de vulcanizacao do latex por radiacao induzida de fonte gama

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Carlos Felipe Pinto

    2005-07-01

    The natural rubber latex (NRL) is industrially crosslinked by the conventional process of vulcanization, which uses sulphur and heat. Otherwise, the network can also be done by the alternative process with ionizing radiation. In this work the crosslinking of NRL was studied by the comparison of the conventional vulcanization system and the ionizing radiation process of {sup 60}C source. The products obtained, the irradiated latex, the irradiated latex with approximately 1% of soy lecithin and the sulphur vulcanized latex were tested by accelerated aging with ultraviolet (UV) and outdoor aging with compostage, tensile strength at break, swelling and gel fraction, fungi micro biota, scanning electron microscopy (SEM), infrared spectroscopy (FTIR) and thermogravimetry and differential scanning calorimetry analysis (TG and DSC). The results showed that the aging with microorganisms have a great influence in the physical properties of the samples. The thermal stability order observed showed that the sulphur vulcanized latex is more resistant, what is probably associated to a network more stable under the aging conditions. On the other hand, the irradiated latex showed intense biodegradation aspects, particularly with the presence of the soy lecithin. (author)

  16. Female teachers' math anxiety affects girls' math achievement.

    Science.gov (United States)

    Beilock, Sian L; Gunderson, Elizabeth A; Ramirez, Gerardo; Levine, Susan C

    2010-02-02

    People's fear and anxiety about doing math--over and above actual math ability--can be an impediment to their math achievement. We show that when the math-anxious individuals are female elementary school teachers, their math anxiety carries negative consequences for the math achievement of their female students. Early elementary school teachers in the United States are almost exclusively female (>90%), and we provide evidence that these female teachers' anxieties relate to girls' math achievement via girls' beliefs about who is good at math. First- and second-grade female teachers completed measures of math anxiety. The math achievement of the students in these teachers' classrooms was also assessed. There was no relation between a teacher's math anxiety and her students' math achievement at the beginning of the school year. By the school year's end, however, the more anxious teachers were about math, the more likely girls (but not boys) were to endorse the commonly held stereotype that "boys are good at math, and girls are good at reading" and the lower these girls' math achievement. Indeed, by the end of the school year, girls who endorsed this stereotype had significantly worse math achievement than girls who did not and than boys overall. In early elementary school, where the teachers are almost all female, teachers' math anxiety carries consequences for girls' math achievement by influencing girls' beliefs about who is good at math.

  17. Diagnosis of toxoplasmosis in pregnancy. Evaluation of latex-protein complexes by immnunoagglutination.

    Science.gov (United States)

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

    2017-07-01

    The aim of this work was to obtain a reagent based on latex particles for ruling out acute toxoplasmosis in pregnant women by immunoagglutination (IA). Latex-protein complexes (LPC) were previously synthesized coupling the recombinant protein of Toxoplasma gondii P22Ag and the homogenate of the parasite to latex particles with different size, chemical functionality and charge density. LPC were tested in IA assays against a panel of 72 pregnant women serum samples. Results were analysed through receiver operating characteristic curves, determining area under the curve (AUC), sensitivity, specificity positive and negative predictive values (PPV and NPV, respectively). It was observed that the antigenicity of proteins was not affected during sensitization by either physical adsorption or covalent coupling. The best results in the sense of maximizing discrimination of low avidity sera from chronic ones were observed for the IA test based on latex particles with carboxyl functionality and the recombinant P22Ag, obtaining an AUC of 0·94, a sensitivity of 100% and a NPV of 100%. In this way, the proposed test could be useful for the toxoplasmosis diagnosis in pregnant women, with the advantages of being cheap, rapid and easy to be implemented.

  18. Thermodynamics of swelling of latex particles with two monomers

    NARCIS (Netherlands)

    Maxwell, I.A.; Kurja, J.; van Doremaele, G.H.J.; German, A.L.

    1992-01-01

    The partitioning of 2 monomers between the latex particle, monomer droplet, and aq. phases of an emulsion polymer latex are measured at satn. swelling of the latex particle phase (corresponding to intervals I and II of an emulsion polymn.). The monomer (Me acrylate, Bu acrylate, styrene) and polymer

  19. Understanding the Home Math Environment and Its Role in Predicting Parent Report of Children's Math Skills.

    Science.gov (United States)

    Hart, Sara A; Ganley, Colleen M; Purpura, David J

    2016-01-01

    There is a growing literature concerning the role of the home math environment in children's math development. In this study, we examined the relation between these constructs by specifically addressing three goals. The first goal was to identify the measurement structure of the home math environment through a series of confirmatory factor analyses. The second goal was to examine the role of the home math environment in predicting parent report of children's math skills. The third goal was to test a series of potential alternative explanations for the relation between the home math environment and parent report of children's skills, specifically the direct and indirect role of household income, parent math anxiety, and parent math ability as measured by their approximate number system performance. A final sample of 339 parents of children aged 3 through 8 drawn from Mechanical Turk answered a questionnaire online. The best fitting model of the home math environment was a bifactor model with a general factor representing the general home math environment, and three specific factors representing the direct numeracy environment, the indirect numeracy environment, and the spatial environment. When examining the association of the home math environment factors to parent report of child skills, the general home math environment factor and the spatial environment were the only significant predictors. Parents who reported doing more general math activities in the home reported having children with higher math skills, whereas parents who reported doing more spatial activities reported having children with lower math skills.

  20. Understanding the Home Math Environment and Its Role in Predicting Parent Report of Children's Math Skills.

    Directory of Open Access Journals (Sweden)

    Sara A Hart

    Full Text Available There is a growing literature concerning the role of the home math environment in children's math development. In this study, we examined the relation between these constructs by specifically addressing three goals. The first goal was to identify the measurement structure of the home math environment through a series of confirmatory factor analyses. The second goal was to examine the role of the home math environment in predicting parent report of children's math skills. The third goal was to test a series of potential alternative explanations for the relation between the home math environment and parent report of children's skills, specifically the direct and indirect role of household income, parent math anxiety, and parent math ability as measured by their approximate number system performance. A final sample of 339 parents of children aged 3 through 8 drawn from Mechanical Turk answered a questionnaire online. The best fitting model of the home math environment was a bifactor model with a general factor representing the general home math environment, and three specific factors representing the direct numeracy environment, the indirect numeracy environment, and the spatial environment. When examining the association of the home math environment factors to parent report of child skills, the general home math environment factor and the spatial environment were the only significant predictors. Parents who reported doing more general math activities in the home reported having children with higher math skills, whereas parents who reported doing more spatial activities reported having children with lower math skills.

  1. Encapsulation of Clay Platelets inside Latex Particles

    NARCIS (Netherlands)

    Voorn, D.J.; Ming, W.; Herk, van A.M.; Fernando, R.H.; Sung, Li-Piin

    2009-01-01

    We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of

  2. Preparation of highly stabilised natural rubber latex for radiation vulcanisation

    International Nuclear Information System (INIS)

    Kulatunge, S.S.; Nadarajah, M.; Kalyani, N.M.V.; Chandralal, H.N.K.K.; Devendra, R.

    1996-01-01

    There is a bright future for radiation vulcanised natural rubber latex (RVNRL) but there are problems in manufacturing it as the centrifuged latex to be used for radiation has to be kept for at least a month or sometimes even three to six months before adding the sensitisers and even then the latex sometimes coagulates on adding the sensitisers. This paper describes a process by which the latex can be stabilised by addition of an anionic soap before centrifuging so that it has a high mechanical stability and hence can be used even within one week of the manufacture of the centrifuged latex

  3. When Math Hurts: Math Anxiety Predicts Pain Network Activation in Anticipation of Doing Math

    Science.gov (United States)

    Lyons, Ian M.; Beilock, Sian L.

    2012-01-01

    Math can be difficult, and for those with high levels of mathematics-anxiety (HMAs), math is associated with tension, apprehension, and fear. But what underlies the feelings of dread effected by math anxiety? Are HMAs’ feelings about math merely psychological epiphenomena, or is their anxiety grounded in simulation of a concrete, visceral sensation – such as pain – about which they have every right to feel anxious? We show that, when anticipating an upcoming math-task, the higher one’s math anxiety, the more one increases activity in regions associated with visceral threat detection, and often the experience of pain itself (bilateral dorso-posterior insula). Interestingly, this relation was not seen during math performance, suggesting that it is not that math itself hurts; rather, the anticipation of math is painful. Our data suggest that pain network activation underlies the intuition that simply anticipating a dreaded event can feel painful. These results may also provide a potential neural mechanism to explain why HMAs tend to avoid math and math-related situations, which in turn can bias HMAs away from taking math classes or even entire math-related career paths. PMID:23118929

  4. When math hurts: math anxiety predicts pain network activation in anticipation of doing math.

    Directory of Open Access Journals (Sweden)

    Ian M Lyons

    Full Text Available Math can be difficult, and for those with high levels of mathematics-anxiety (HMAs, math is associated with tension, apprehension, and fear. But what underlies the feelings of dread effected by math anxiety? Are HMAs' feelings about math merely psychological epiphenomena, or is their anxiety grounded in simulation of a concrete, visceral sensation - such as pain - about which they have every right to feel anxious? We show that, when anticipating an upcoming math-task, the higher one's math anxiety, the more one increases activity in regions associated with visceral threat detection, and often the experience of pain itself (bilateral dorso-posterior insula. Interestingly, this relation was not seen during math performance, suggesting that it is not that math itself hurts; rather, the anticipation of math is painful. Our data suggest that pain network activation underlies the intuition that simply anticipating a dreaded event can feel painful. These results may also provide a potential neural mechanism to explain why HMAs tend to avoid math and math-related situations, which in turn can bias HMAs away from taking math classes or even entire math-related career paths.

  5. When math hurts: math anxiety predicts pain network activation in anticipation of doing math.

    Science.gov (United States)

    Lyons, Ian M; Beilock, Sian L

    2012-01-01

    Math can be difficult, and for those with high levels of mathematics-anxiety (HMAs), math is associated with tension, apprehension, and fear. But what underlies the feelings of dread effected by math anxiety? Are HMAs' feelings about math merely psychological epiphenomena, or is their anxiety grounded in simulation of a concrete, visceral sensation - such as pain - about which they have every right to feel anxious? We show that, when anticipating an upcoming math-task, the higher one's math anxiety, the more one increases activity in regions associated with visceral threat detection, and often the experience of pain itself (bilateral dorso-posterior insula). Interestingly, this relation was not seen during math performance, suggesting that it is not that math itself hurts; rather, the anticipation of math is painful. Our data suggest that pain network activation underlies the intuition that simply anticipating a dreaded event can feel painful. These results may also provide a potential neural mechanism to explain why HMAs tend to avoid math and math-related situations, which in turn can bias HMAs away from taking math classes or even entire math-related career paths.

  6. 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 molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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.

  8. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    International Nuclear Information System (INIS)

    Määttänen, Anni; Ihalainen, Petri; Törngren, Björn; Rosqvist, Emil; Pesonen, Markus; Peltonen, Jouko

    2016-01-01

    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_2)_1_1OH (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

  9. 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

  10. Radiation vulcanization of Philippine natural rubber latex

    International Nuclear Information System (INIS)

    Dela Rosa, Alumanda M.; Abad, Lucille V.; Sta, Lorna P.; Ana-Relleve; Tranquilan-Aranilla, Charito O.; Pascual, Cristina L.

    1996-01-01

    The response of Philippine natural rubber latex to radiation vulcanization and the stability of the irradiated natural rubber latex (INRL) upon storage and aging were investigated. Commercially available high ammonia (HA) concentrated lattices obtained from various rubber plantations in Mindanao Island were treated with 5 phr of n-butyl acrylate (nBA), and gamma-irradiated at the PNRI sup 60 Co irradiation facility at dose rate of 2.57 KGy/hr. Unirradiated cast latex films gave different green strength which varied from 2 - 11 MPa. Cast films from INRL exhibited maximum tensile strengths of 25 - 32 MPa at a radiation dose of 15 kGy. Higher tensile strengths were obtained from cast films with low Mg and high nitrogen contents. Thermal analysis using thermogravimetry (TG) revealed one major decomposition product at 374 degree C - 377 degree C. Its rate of decomposition decreased to a minimum at 15 kGy, then increased as radiation dose increased. This trend correlated well with the tensile strength measurements. The stability of the INRL upon storage and aging is an essential parameter to the rubber latex industry. For storage studies, INRL was stored for various periods of time. It was found that the pH and total solids content of the stored INRL did not change significantly after 12 months of storage; the MST values remained at above 100 seconds, and the viscosity decreased with time. The cast films exhibited a decline in tensile strength, modulus 300% and crosslinking density upon storage. While there were observed changes in the physical properties of the IRNL during the storage period, the data indicate that these properties were within values acceptable to the latex industry. Tests on the aging properties of INRL film were undertaken. It was shown that among the chemical antioxidants presently used by the latex industry. TNPP demonstrated the highest antioxidant property, followed by Antage DAHQ and Vulcanox BKF. Our data indicate that the natural rubber latex

  11. Radiation vulcanization of Philippine natural rubber latex

    International Nuclear Information System (INIS)

    Dela Rosa, A.M.; Abad, L.V.; Sta.Ana-Relleve, L.P.; Tranquilan-Aranilla, C.O.; Pascual, C.L.

    1996-01-01

    The response of Philippine natural rubber latex to irradiation vulcanization and the stability of the irradiated natural rubber latex (INRL) upon storage and aging were investigated. Commercially available high ammonia (HA) concentrated latices obtained from various rubber plantations in Mindanao island were treated with 5 phr of n-butyl acrylate (nBA), and gamma-irradiated at the PNRI 60 Co irradiation facility at a dose rate of 2.57 kGy/hr. Unirradiated cast latex films gave different green strengths which varied from 2-11 MPa. Cast films from INRL exhibited maximum tensile strengths were obtained from cast films with low Mg and high nitrogen contents. Thermal analysis using thermogravimetry (TG) revealed one major decomposition product at 374 o -377 o C. Its rate of decomposition decreased to a minimum at 15 kGy, then increased as radiation dose was increased. This trend correlated well with the tensile strength measurements. The stability of the INRL upon storage and aging is an essential parameter to the rubbe latex industry. For storage studies, INRL was stored for various periods of time. It was found that the pH and total solids content of the stored INRL did not change significantly after 12 months of storage; the MST values remained at above 1000 seconds, and the viscosity decreased with time. The cast films exhibited a decline in tensile strength, modulus 300% , and crosslinking density upon storage. While there were observed changes in the physical properties of the INRL during the storage period, the data indicate that these properties were within values acceptable to the latex industry. Tests on the aging properties of INRL films were undertaken. It was shown that among the chemical antioxidants presently used by the latex industry, TNPP demonstrated the highest antioxidant property, followed by Antage DAHQ and Vulcanox BKF. Our data indicate that the natural rubber latex produced and processed in the Philippines is suited for radiation vulcanization

  12. Understanding the Home Math Environment and Its Role in Predicting Parent Report of Children’s Math Skills

    Science.gov (United States)

    Ganley, Colleen M.; Purpura, David J.

    2016-01-01

    There is a growing literature concerning the role of the home math environment in children’s math development. In this study, we examined the relation between these constructs by specifically addressing three goals. The first goal was to identify the measurement structure of the home math environment through a series of confirmatory factor analyses. The second goal was to examine the role of the home math environment in predicting parent report of children’s math skills. The third goal was to test a series of potential alternative explanations for the relation between the home math environment and parent report of children’s skills, specifically the direct and indirect role of household income, parent math anxiety, and parent math ability as measured by their approximate number system performance. A final sample of 339 parents of children aged 3 through 8 drawn from Mechanical Turk answered a questionnaire online. The best fitting model of the home math environment was a bifactor model with a general factor representing the general home math environment, and three specific factors representing the direct numeracy environment, the indirect numeracy environment, and the spatial environment. When examining the association of the home math environment factors to parent report of child skills, the general home math environment factor and the spatial environment were the only significant predictors. Parents who reported doing more general math activities in the home reported having children with higher math skills, whereas parents who reported doing more spatial activities reported having children with lower math skills. PMID:28005925

  13. 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...

  14. EDITORIALS Latex allergy: 'Plight, rights and fights'

    African Journals Online (AJOL)

    anaphylaxis and life-threatening food allergies to cross-reacting fruit allergens such as kiwi, banana, tomato and chestnuts). Latex allergy is also encountered more frequently in children with spina bifida than in other hospitalised children.[7] Sensitisation is usually confirmed by commercial latex allergy skinprick testing or by ...

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  16. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    Science.gov (United States)

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

    2013-06-01

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

  17. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  18. Home Healthcare Workers: How to Prevent Latex Allergies

    Science.gov (United States)

    ... can help prevent allergic reactions for both home healthcare workers and their clients. LATEX EXPOSURE REACTIONS Three ... being used). • Inform your employer and your personal healthcare professionals that you have latex allergy. • Wear a ...

  19. The role of self-math overlap in understanding math anxiety and the relation between math anxiety and performance.

    Science.gov (United States)

    Necka, Elizabeth A; Sokolowski, H Moriah; Lyons, Ian M

    2015-01-01

    Recent work has demonstrated that math anxiety is more than just the product of poor math skills. Psychosocial factors may play a key role in understanding what it means to be math anxious, and hence may aid in attempts to sever the link between math anxiety and poor math performance. One such factor may be the extent to which individuals integrate math into their sense of self. We adapted a well-established measure of this degree of integration (i.e., self-other overlap) to assess individuals' self-math overlap. This non-verbal single-item measure showed that identifying oneself with math (having higher self-math overlap) was strongly associated with lower math anxiety (r = -0.610). We also expected that having higher self-math overlap would leave one especially susceptible to the threat of poor math performance to the self. We identified two competing hypotheses regarding how this plays out in terms of math anxiety. Those higher in self-math overlap might be more likely to worry about poor math performance, exacerbating the negative relation between math anxiety and math ability. Alternatively, those higher in self-math overlap might exhibit self-serving biases regarding their math ability, which would instead predict a decoupling of the relation between their perceived and actual math ability, and in turn the relation between their math ability and math anxiety. Results clearly favored the latter hypothesis: those higher in self-math overlap exhibited almost no relation between math anxiety and math ability, whereas those lower in self-math overlap showed a strong negative relation between math anxiety and math ability. This was partially explained by greater self-serving biases among those higher in self-math overlap. In sum, these results reveal that the degree to which one integrates math into one's self - self-math overlap - may provide insight into how the pernicious negative relation between math anxiety and math ability may be ameliorated.

  20. The role of self-math overlap in understanding math anxiety and the relation between math anxiety and performance

    Science.gov (United States)

    Necka, Elizabeth A.; Sokolowski, H. Moriah; Lyons, Ian M.

    2015-01-01

    Recent work has demonstrated that math anxiety is more than just the product of poor math skills. Psychosocial factors may play a key role in understanding what it means to be math anxious, and hence may aid in attempts to sever the link between math anxiety and poor math performance. One such factor may be the extent to which individuals integrate math into their sense of self. We adapted a well-established measure of this degree of integration (i.e., self-other overlap) to assess individuals’ self-math overlap. This non-verbal single-item measure showed that identifying oneself with math (having higher self-math overlap) was strongly associated with lower math anxiety (r = -0.610). We also expected that having higher self-math overlap would leave one especially susceptible to the threat of poor math performance to the self. We identified two competing hypotheses regarding how this plays out in terms of math anxiety. Those higher in self-math overlap might be more likely to worry about poor math performance, exacerbating the negative relation between math anxiety and math ability. Alternatively, those higher in self-math overlap might exhibit self-serving biases regarding their math ability, which would instead predict a decoupling of the relation between their perceived and actual math ability, and in turn the relation between their math ability and math anxiety. Results clearly favored the latter hypothesis: those higher in self-math overlap exhibited almost no relation between math anxiety and math ability, whereas those lower in self-math overlap showed a strong negative relation between math anxiety and math ability. This was partially explained by greater self-serving biases among those higher in self-math overlap. In sum, these results reveal that the degree to which one integrates math into one’s self – self-math overlap – may provide insight into how the pernicious negative relation between math anxiety and math ability may be ameliorated. PMID

  1. The role of self-math overlap in understanding math anxiety and the relation between math anxiety and performance

    Directory of Open Access Journals (Sweden)

    Elizabeth A Necka

    2015-10-01

    Full Text Available Recent work has demonstrated that math anxiety is more than just the product of poor math skills. Psychosocial factors may play a key role in understanding what it means to be math anxious, and hence may aid in attempts to sever the link between math anxiety and poor math performance. One such factor may be the extent to which individuals integrate math into their sense of self. We adapted a well-established measure of this degree of integration (i.e., self-other overlap to assess individuals’ self-math overlap. This nonverbal single-item measure showed that identifying oneself with math (having higher self-math overlap was strongly associated with lower math anxiety (r=-.610. We also expected that having higher self-math overlap would leave one especially susceptible to the threat of poor math performance to the self. We identified two competing hypotheses regarding how this plays out in terms of math anxiety. Those higher in self-math overlap might be more likely to worry about poor math performance, exacerbating the negative relation between math anxiety and math ability. Alternatively, those higher in self-math overlap might exhibit self-serving biases regarding their math ability, which would instead predict a decoupling of the relation between their perceived and actual math ability, and in turn the relation between their math ability and math anxiety. Results clearly favored the latter hypothesis: those higher in self-math overlap exhibited almost no relation between math anxiety and math ability, whereas those lower in self-math overlap showed a strong negative relation between math anxiety and math ability. This was partially explained by greater self-serving biases among those higher in self-math overlap. In sum, these results reveal that the degree to which one integrates math into one’s self – self-math overlap – may provide insight into how the pernicious negative relation between math anxiety and math ability may be

  2. Latex allergy: new insights to explain different sensitization profiles in different risk groups.

    Science.gov (United States)

    Peixinho, C; Tavares-Ratado, P; Tomás, M R; Taborda-Barata, L; Tomaz, C T

    2008-07-01

    Differences in latex allergen sensitization profiles have been described between children subjected to repetitive surgical interventions and health care workers (HCW). 'Major' allergens for patients with spina bifida are Hev b 1, 3 and 7, while for HCW, 'major' allergens are Hev b 2, 5, 6.01 and 13. The reason for these differential sensitization profiles is currently unknown. To investigate latex allergen profiles on internal and external surfaces of natural rubber latex gloves. Eighty-two samples of commonly used surgical gloves (41 glove brands) were used for analysis. Specific allergen levels of Hev b 1, 3, 5 and 6.02 on both surfaces of the gloves were quantified using an enzyme immunometric assay, a FITkit (FIT Biotech, Tampere, Finland). Differences in allergen levels were observed between internal and external surfaces of all glove types. Concentrations of Hev b 1 and Hev b 3 were significantly higher on external surfaces, while internal surfaces had higher allergen levels of Hev b 5 and Hev b 6.02. Analysis of surgical and examination gloves, powdered and nonpowdered gloves also showed that the content of Hev b 5 and Hev b 6.02 was significantly higher on internal surfaces while that of Hev b 1 and Hev b 3 was higher on external surfaces. Our study showed different allergen profiles on internal and external surfaces of natural rubber latex gloves. These results may suggest a relationship between latex allergen localization and sensitization routes in different risk groups.

  3. Angiogenic activity of Synadenium umbellatum Pax latex

    Directory of Open Access Journals (Sweden)

    PR. Melo-Reis

    Full Text Available Synadenium umbellatum Pax, popularly known as "cola-nota", is a medicinal plant that grows in tropical regions. Latex of this plant is used to treat various diseases such as diabetes mellitus, Hansen´s disease, tripanosomiases, leukemia and several malignant tumors. In the present study, the angiogenic activity of S. umbellatum latex was evaluated using the chick embryo chorioallantoic membrane (CAM assay. Results showed significant increase of the vascular net (p < 0.05 compared to the negative control (H2O. The histological analysis was in accordance with the results obtained. In conclusion, our data indicate that S. umbellatum latex, under the conditions of this research, presented angiogenic effect.

  4. Assay of anti-HBs antibodies using a recombinant antigen and latex particle counting: comparison with five commercial tests.

    Science.gov (United States)

    Galanti, L M; Cornu, C; Masson, P L; Robert, A R; Becheanu, D; Lamy, M E; Cambiaso, C L

    1991-05-01

    An assay of anti-HBs antibodies based on agglutination of latex particles coated with recombinant HBs-antigen was compared with Abbott radioimmunoassay (Abbott-RIA), which uses a human plasma-derived antigen. The population examined consisted of 76 Abbott-RIA anti-HBs-negative prevaccinated subjects and 1044 serum samples anti-HBs found positive by Abbott-RIA, including 283 samples of subjects vaccinated either with a human plasma-derived vaccine (group A; n = 180) or with a recombinant vaccine (group B; n = 103). Correlation coefficients between the two techniques were respectively r = 0.89 for the whole population (n = 1044), r = 0.98 in group A and r = 0.74 in group B. Anti-HBs titres were higher with latex than with RIA in group B as shown by the regression slopes: latex = 508 + 1.11 RIA in group A and latex = -1138 + 3.97 RIA in group B, suggesting that some vaccinated subjects from group B produced antibodies against epitopes proper to the recombinant antigen. In the prevaccinated population and in group A, the latex results were compared with those of radioimmunoassays (Abbott, Sorin) and enzyme immunoassays (Behring, Roche, Pasteur). Only the Roche-EIA detected anti-HBs in the prevaccinated subjects. The correlation between the various immunoassays was r greater than 0.96 only for values higher than 100 IU/l.

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

  6. More than Counting: Whole Math Activities for Preschool and Kindergarten.

    Science.gov (United States)

    Moomaw, Sally; Hieronymus, Brenda

    This book presents extensive sampling of a "whole math" curriculum for preschool and kindergarten children ages 3 and older. An introductory chapter is followed by seven curriculum chapters that discuss math manipulatives, collections, grid games, path games, graphing, math and gross-motor play, and the "math suitcase." Each chapter is divided…

  7. Triterpenoid biosynthesis in Euphorbia lathyris latex

    International Nuclear Information System (INIS)

    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 50 concentration of 3.2 μM. 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 50 of 4 μM. 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- 3 H-mevalonic acid and incubating latex with a mixture of this and 14 C-mevalonic acid. From the 3 H/ 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

  8. Studies on physico-chemical and mechanical properties of the irradiated latex modified mortar

    International Nuclear Information System (INIS)

    Yassene, A.A.M.A.

    2009-01-01

    This thesis contains three chapter; chapter(I): Introduction and literature review on:- Introduction to polymer. - Mechanism of polymer-cement co-matrix formation.-Sulphate attack. - Solidification /stabilization of heavy metal in cement mortar. chapter(II): Materials and experimental techniques that include: 1- Preparation of latex polymer films from different polymer latices of styrene butadine rubber latex (SBR), poly (styrene-acrylic ester) latex (SAE) and vinylacetate /versatic -ester copolymer latex (C2A). The effect of γ-irradiation dose on the physico - chemical and mechanical properties of different latex polymer films was studied.2- Preparation of latex polymer-modified cement mortar with different ratios of cement: latex polymer and different curing method.3- Solidification /stabilization (S/S) of electroplating heavy metal precipitate in latex polymer- modified mortar with different cement /electroplating heavy metal sludge ratio. chapter(III) results and discussion

  9. Math anxiety and math performance in children: The mediating roles of working memory and math self-concept.

    Science.gov (United States)

    Justicia-Galiano, M José; Martín-Puga, M Eva; Linares, Rocío; Pelegrina, Santiago

    2017-12-01

    Numerous studies, most of them involving adolescents and adults, have evidenced a moderate negative relationship between math anxiety and math performance. There are, however, a limited number of studies that have addressed the mechanisms underlying this relation. This study aimed to investigate the role of two possible mediational mechanisms between math anxiety and math performance. Specifically, we sought to test the simultaneous mediating role of working memory and math self-concept. A total of 167 children aged 8-12 years participated in this study. Children completed a set of questionnaires used to assess math and trait anxiety, math self-concept as well as measures of math fluency and math problem-solving. Teachers were asked to rate each student's math achievement. As measures of working memory, two backward span tasks were administered to the children. A series of multiple mediation analyses were conducted. Results indicated that both mediators (working memory and math self-concept) contributed to explaining the relationship between math anxiety and math achievement. Results suggest that working memory and self-concept could be worth considering when designing interventions aimed at helping students with math anxiety. Longitudinal designs could also be used to better understand the mediational mechanisms that may explain the relationship between math anxiety and math performance. © 2017 The British Psychological Society.

  10. 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.

  11. Synthesis and characterization of fluorinated polyacrylate latex emulsified with novel surfactants.

    Science.gov (United States)

    Zhang, Cuifeng; Xu, Tingting; Bao, Zhongbin; Chen, Lijun

    2017-01-01

    The fluorinated polyacrylate latex were successfully prepared with semi- continuous seeded emulsion polymerization of butyl acrylate (BA), methyl methacrylate (MMA) and hexafluorobutyl methacrylate (HFMA) which was initiated with potassium persulfate (KPS) initiator and emulsified with the novel mixed surfactants of sodium lauryl glutamate (SLG) and alkylphenol ethoxylates (OP-10). The structure of the resultant latex was confirmed by Fourier transform infrared spectroscopy (FTIR). The particle size of the latex was measured by Zetatrac dynamic light scattering detector. The film of latex was tested by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and contact angle (CA). The optimum conditions of preparing the novel fluorinated polyacrylate latex are optimized and the results are as follows: the amount of emulsifiers is 4.0%; mass ratio of SLG to OP-10 is 1:1, the amount of the initiator is 0.6%. The mass ratio of MMA to BA is 1:1 and the amount of HFMA is 7.0%. In this case, the conversion is high and the polymerization stability is good. In addition, the water resistance and thermal properties of the latex films were improved significantly in comparison with the film of the latex prepared without the fluorinated monomer.

  12. 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.

  13. Culture and math.

    Science.gov (United States)

    Tcheang, Lili

    2014-01-01

    Cultural differences have been shown across a number of different cognitive domains from vision, language, and music. Mathematical cognition is another domain that is an integral part of modern society and because there are a fixed number of ways in which many math operations can be performed, it is also an apposite tool for cultural comparisons. This discussion examines the literature on mathematical processing in accordance with culture, summarizing the brain regions involved across various mathematical tasks. In doing so, we provide a clear picture of the anatomical similarities and differences between cultures when performing different math tasks. This information is useful to explore the possibility of enhancement of mathematical skills, where different strategies may be applicable in accordance with culture. It also contributes to the evolutionary development of different math skills and the growing theory that anatomical and behavioral studies must account for the cultural identity of their sample.

  14. 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 previ......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...... to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m...

  15. Determination of the content of alkyl ketene dimer in its latex by an ionic-liquid assisted headspace gas chromatography.

    Science.gov (United States)

    Yan, Ning; Wan, Xiao-Fang; Chai, Xin-Sheng; Chen, Run-Quan; Chen, Chun-Xia

    2017-12-29

    This paper reports on an ionic-liquid assisted headspace gas chromatographic (HS-GC) for the determination of the content of alkyl ketene dimer (AKD) in its latex samples, in which the GC system was equipped with a thermal conductivity detector (TCD). The method was based on the AKD hydrolysis conducted in 1-butyl-3-methylimidazolium chloride (ionic-liquid) added medium at 100°C for 10min in a closed headspace sample vial, and the measured CO 2 (the resulting product of the hydrolysis) by HS-GC. The results showed that the present method has a good measurement precision (RSD <2.3%) and accuracy (recoveries from 96 - 105%), and the limit of quantitation (LOQ) is 0.9%. The present method is very suitable to be used for the routine check of AKD content in its latex sample in mill applications. The study also showed that the content of AKD in the tested commercial latex samples were in the range of 3.5-12%. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Detection of latex allergens by immunoelectron microscopy in ambient air (PM10) in Oslo, Norway (1997-2003).

    Science.gov (United States)

    Namork, Ellen; Kurup, Viswanath P; Aasvang, Gunn Marit; Johansen, Bjørn V

    2004-11-01

    The authors collected ambient air along two highways in Oslo to investigate the annual variations in particulate matter (PM10) and the presence of latex as an outdoor allergen. PMI, was monitored for a period of five years, during which time the use of studded winter tires was reduced. The presence of latex and of common aeroallergens was examined directly on the collection filters with immunoelectron microscopy visualized in a scanning electron microscope. The annual variation in PM10 was similar over the five years of sampling, with increased mass concentrations in winter. Statistical analysis indicated no major effect from the change to nonstudded tires. The most important factors influencing the PM10 concentration were meteorological parameters like wind and rain. Immnunolabeling of the filters showed latex as an outdoor allergen that adhered to carbon aggregates from vehicle emission. The results also indicated cross-reactive epitopes among the common allergens investigated, which for sensitized subjects may add to the risk of developing latex allergy.

  17. Radiation response of Philippine natural rubber latex

    International Nuclear Information System (INIS)

    Dela Rosa, A.M.; Abad, L.V.; Ana-Relleve, L.S.; Tranquilan-Aranilla, C.; Pascual, C.L.

    1998-01-01

    Our earlier work has shown that the natural rubber latex (NRL) produced and processed in the Philippines is suited for radiation vulcanization. The cast films from NRL with 50% TSC exhibited maximum tensile strengths of 25-32 MPa at 15 kGy, which is the vulcanization dose or Dv. In the manufacture of dipped NRL products, certain specifications such as %TSC, protein content and tensile properties, must be met to ensure an acceptable product. For radiation vulcanization of natural rubber latex (RVNRL) to be accepted as an alternative process, it must also meet the requirements. Thus, this paper presents additional data on the radiation response of local NRL at different total solids contents (TSC), leachable proteins from NRL films as a function of dose, and the thermal activities of irradiated natural rubber latex (INRL). Different formulations of NRL showed varying tolerances to nBA. Data showed that as %TSC increases, the maximum concentration of nBA that can be added without affecting the stability of the latex decreases. The Dv increases as the %TSC increases and the nBA content decreases. This difference in response may be attributed to a lower concentration of nBA in formulations with higher %TSC. These data indicate that the parameters in the radiation treatment will be dictated by the intended applications of INRL. The thermogravimetric data showed greater stability of INRL to thermal oxidation relative to the unirradiated NRL, which correlates directly with the tensile properties of the INRL. A radiation dose of 10 kGy increased the amount of proteins leached from cast latex films. The amount of extractable proteins did not increase significantly at higher doses. The SDS PAGE analysis of the extractable proteins from unirradiated latex film showed distinct bands. An additional band at 60 Kda appeared at 10 kGy. All these bands became diffuse at higher doses, indicating the radiolysis of the proteins

  18. Intergenerational Effects of Parents' Math Anxiety on Children's Math Achievement and Anxiety.

    Science.gov (United States)

    Maloney, Erin A; Ramirez, Gerardo; Gunderson, Elizabeth A; Levine, Susan C; Beilock, Sian L

    2015-09-01

    A large field study of children in first and second grade explored how parents' anxiety about math relates to their children's math achievement. The goal of the study was to better understand why some students perform worse in math than others. We tested whether parents' math anxiety predicts their children's math achievement across the school year. We found that when parents are more math anxious, their children learn significantly less math over the school year and have more math anxiety by the school year's end-but only if math-anxious parents report providing frequent help with math homework. Notably, when parents reported helping with math homework less often, children's math achievement and attitudes were not related to parents' math anxiety. Parents' math anxiety did not predict children's reading achievement, which suggests that the effects of parents' math anxiety are specific to children's math achievement. These findings provide evidence of a mechanism for intergenerational transmission of low math achievement and high math anxiety. © The Author(s) 2015.

  19. Radiation Vulcanization of Natural Rubber Latex (RVNRL): A Potential Material for Nuclear Power Plant Gloves

    International Nuclear Information System (INIS)

    Pairu Ibrahim; Wan Manshol Wan Zain; Keong, C.C.; Mohd Noorwadi Mat Lazim

    2011-01-01

    Radiation vulcanization of natural rubber latex has great potential for the production of nuclear power plant gloves due to its low ash and mineral content. And this is in-line with the role played by Malaysian Nuclear Agency as Technical Supporting Organization for Nuclear Power Program. This paper discussed the evaluation done to determine ash content in RVNRL and SVNRL films. Both samples were prepared using casting technique and the properties were compared. Films prepared from raw latex without any vulcanizing agent were regarded as a control. (author)

  20. Antibacterial activity of the latex of Argemone ochroleuca Sweet

    International Nuclear Information System (INIS)

    Saad A. Alamri; Mahmoud F. Moustafa

    2010-01-01

    To investigate the antibacterial effect of the crude latex of Argemone ochroleuca (A. ochroleuca) as antibacterial potential against a range of human pathogenic bacteria. This study was carried out at King Khalid University, Abha, Kingdom of Saudi Arabia from January to March 2010. Seventeen ml of fresh latex from A. ochroleuca Sweet was collected, and the antibacterial activity of crude and diluted latex were examined using one ml of standardized inoculum suspension, and using the agar diffusion method test against Bacillus subtilis, Enterobacter aerogenes, Micrococcus luteus, Escherichia coli, and Staphylococcus aureus. All inoculated plates were incubated aerobically at 290C for 48 hours. The diameter of the zones of inhibition was measured to the nearest mm. The crude latex of A. ochroleuca exhibited a potent antibacterial effect on all bacterial strains examined. The zones of inhibition against the tested bacteria were found in the range of 9.30 - 40.3 mm along with their respective minimum inhibitory concentration values 100 ul/ml. The observable inhibition on selected bacteria by latex of A. ochroleuca makes it a promising alternative as a potential source of natural antibacterial (Author).

  1. Thrombin like activity of Asclepias curassavica L. latex: action of cysteine proteases.

    Science.gov (United States)

    Shivaprasad, H V; Rajesh, R; Nanda, B L; Dharmappa, K K; Vishwanath, B S

    2009-05-04

    To validate the scientific basis of plant latex to stop bleeding on fresh cuts. Cysteine protease(s) from Asclepias curassavica (Asclepiadaceae) plant latex was assessed for pro-coagulant and thrombin like activities. A waxy material from the latex of Asclepias curassavica latex was removed by freezing and thawing. The resulted latex enzyme fraction was assayed for proteolytic activity using denatured casein as substrate. Its coagulant activity and thrombin like activity were determined using citrated plasma and pure fibrinogen, respectively. Inhibition studies were performed using specific protease inhibitors to know the type of protease. The latex enzyme fraction exhibited strong proteolytic activity when compared to trypsin and exerted pro-coagulant action by reducing plasma clotting time from 195 to 58 s whereas trypsin reduced clotting time marginally from 195 to 155 s. The pro-coagulant activity of this enzyme fraction was exerted by selectively hydrolyzing A alpha and B beta subunits of fibrinogen to form fibrin clot when pure fibrinogen was used as substrate as assessed by fibrinogen-agarose plate method and fibrinogen polymerization assay. Trypsin failed to induce any fibrin clot under similar conditions. The electrophoretic pattern of latex enzyme fraction-induced fibrin clot was very much similar to that of thrombin-induced fibrin clot and mimic thrombin like action. The proteolytic activity including thrombin like activity of Asclepias curassavica latex enzyme fraction was completely inhibited by iodoaceticacid (IAA). Cysteine proteases from Asclepias curassavica latex exhibited strong pro-coagulant action and were found to be specific in its action (Thrombin like). This could be the basis for the use of plant latex in pharmacological applications that justify their use as folk medicine.

  2. Neural correlates of math anxiety - an overview and implications.

    Science.gov (United States)

    Artemenko, Christina; Daroczy, Gabriella; Nuerk, Hans-Christoph

    2015-01-01

    Math anxiety is a common phenomenon which can have a negative impact on numerical and arithmetic performance. However, so far little is known about the underlying neurocognitive mechanisms. This mini review provides an overview of studies investigating the neural correlates of math anxiety which provide several hints regarding its influence on math performance: while behavioral studies mostly observe an influence of math anxiety on difficult math tasks, neurophysiological studies show that processing efficiency is already affected in basic number processing. Overall, the neurocognitive literature suggests that (i) math anxiety elicits emotion- and pain-related activation during and before math activities, (ii) that the negative emotional response to math anxiety impairs processing efficiency, and (iii) that math deficits triggered by math anxiety may be compensated for by modulating the cognitive control or emotional regulation network. However, activation differs strongly between studies, depending on tasks, paradigms, and samples. We conclude that neural correlates can help to understand and explore the processes underlying math anxiety, but the data are not very consistent yet.

  3. 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.

  4. 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.

  5. 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

  6. Cognitive consistency and math-gender stereotypes in Singaporean children.

    Science.gov (United States)

    Cvencek, Dario; Meltzoff, Andrew N; Kapur, Manu

    2014-01-01

    In social psychology, cognitive consistency is a powerful principle for organizing psychological concepts. There have been few tests of cognitive consistency in children and no research about cognitive consistency in children from Asian cultures, who pose an interesting developmental case. A sample of 172 Singaporean elementary school children completed implicit and explicit measures of math-gender stereotype (male=math), gender identity (me=male), and math self-concept (me=math). Results showed strong evidence for cognitive consistency; the strength of children's math-gender stereotypes, together with their gender identity, significantly predicted their math self-concepts. Cognitive consistency may be culturally universal and a key mechanism for developmental change in social cognition. We also discovered that Singaporean children's math-gender stereotypes increased as a function of age and that boys identified with math more strongly than did girls despite Singaporean girls' excelling in math. The results reveal both cultural universals and cultural variation in developing social cognition. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. 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

  8. Universals and Specifics of Math Self-Concept, Math Self-Efficacy, and Math Anxiety across 41 PISA 2003 Participating Countries

    Science.gov (United States)

    Lee, Jihyun

    2009-01-01

    The overarching goal of the present study is to investigate the factorial structure of three closely related constructs: math self-concept, math self-efficacy, and math anxiety. The factorial structure consisting of three factors, each representing math self-concept, math self-efficacy, and math anxiety, is supported in all 41 countries employed…

  9. College Math Assessment: SAT Scores vs. College Math Placement Scores

    Science.gov (United States)

    Foley-Peres, Kathleen; Poirier, Dawn

    2008-01-01

    Many colleges and university's use SAT math scores or math placement tests to place students in the appropriate math course. This study compares the use of math placement scores and SAT scores for 188 freshman students. The student's grades and faculty observations were analyzed to determine if the SAT scores and/or college math assessment scores…

  10. Taking Math Anxiety out of Math Instruction

    Science.gov (United States)

    Shields, Darla J.

    2007-01-01

    To take math anxiety out of math instruction, teachers need to first know how to easily diagnose it in their students and second, how to analyze causes. Results of a recent study revealed that while students believed that their math anxiety was largely related to a lack of mathematical understanding, they often blamed their teachers for causing…

  11. Radiation vulcanization of natural rubber latex sensitized with commercial gases

    International Nuclear Information System (INIS)

    Chirinos, H.; Lugao, A.

    2002-01-01

    The industrial activities using natural rubber latex are fully compatible with rural areas in Amazon and other places in Brazil, as well as in other tropical countries. However the classical sulfur vulcanization presents many occupational problems for the workers in rural areas. Radiation vulcanization of natural rubber latex is a much more friendly process as sulfur compounds are not needed for crosslinking, although chemicals as acrylate monomers, particularly multifunctional acrylates are still used as sensitizers for radiation processes. Two commercial gases, acetylene and butadiene, were selected as sensitizers for the radiation vulcanization of natural rubber latex instead of acrylates. These gases accelerate the crosslinking rates of the cure process and lower the radiation dose required to achieve vulcanization of natural rubber latex and improve the mechanical properties to reduce the tackiness of rubber goods. (author)

  12. Radiation vulcanization of natural rubber latex sensitized with commercial gases

    Energy Technology Data Exchange (ETDEWEB)

    Chirinos, H.; Lugao, A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    2002-07-01

    The industrial activities using natural rubber latex are fully compatible with rural areas in Amazon and other places in Brazil, as well as in other tropical countries. However the classical sulfur vulcanization presents many occupational problems for the workers in rural areas. Radiation vulcanization of natural rubber latex is a much more friendly process as sulfur compounds are not needed for crosslinking, although chemicals as acrylate monomers, particularly multifunctional acrylates are still used as sensitizers for radiation processes. Two commercial gases, acetylene and butadiene, were selected as sensitizers for the radiation vulcanization of natural rubber latex instead of acrylates. These gases accelerate the crosslinking rates of the cure process and lower the radiation dose required to achieve vulcanization of natural rubber latex and improve the mechanical properties to reduce the tackiness of rubber goods. (author)

  13. Preparation of irradiated natural rubber latex-styrene copolymer for electrical gloves

    International Nuclear Information System (INIS)

    Made Sumarti Kardha

    2010-01-01

    Research on irradiated natural rubber latex-styrene copolymer to prepare electrical glove have been done. Vulcanization of natural rubber latex (NRL) was done by mixing 2 phr (per hundred of rubber) of normal butyl acrylate (n-BA) emulsion then irradiated with ã-ray "6"0Co at the dose of 30 kGy producing irradiated natural rubber latex (INRL). Natural rubber latex-styrene copolymers (SC) were prepared by mixing NRL and styrene monomer at styrene concentrations of 50 phr, 75 phr, 100 phr, 500 phr and irradiated at the doses of 15 kGy, 30 kGy and 45 kGy, then characterized their latex and film properties to obtain optimum SC of SC50. This optimum SC, SC50 then mixed with IRNL at the weight ratio of 0/100, 30/70, 50/50, 70/30 and 100/0, to produce irradiated natural rubber latex-styrene copolymer. The properties of copolymer rubber films made by dipping process i.e., % conversion, total solid content, latex viscosity, tensile strength, modulus 300 %, elongation at break, electrical resistance and dielectric constant were then characterized. Characterization result showed that (INRL-SC50) with 50/50 ratio irradiated at the dose of 30 kGy, have % conversion of 80.93 %, electrical resistivity of 1.73 x 10"1"4 Ohm cm and dielectric constant of 2.76 which fulfill the requirement as material for electrical gloves. (author)

  14. A Study of Perceptions of Math Mindset, Math Anxiety, and View of Math by Young Adults

    Science.gov (United States)

    Hocker, Tami

    2017-01-01

    This study's purpose was to determine whether instruction in growth math mindset led to change in perceptions of 18-22-year-old at-risk students in math mindset, math anxiety, and view of math. The experimental curriculum was created by the researcher with the guidance of experts in mathematics and education and focused on the impact of brain…

  15. 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.

  16. 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.

  17. Neural correlates of math anxiety – an overview and implications

    Science.gov (United States)

    Artemenko, Christina; Daroczy, Gabriella; Nuerk, Hans-Christoph

    2015-01-01

    Math anxiety is a common phenomenon which can have a negative impact on numerical and arithmetic performance. However, so far little is known about the underlying neurocognitive mechanisms. This mini review provides an overview of studies investigating the neural correlates of math anxiety which provide several hints regarding its influence on math performance: while behavioral studies mostly observe an influence of math anxiety on difficult math tasks, neurophysiological studies show that processing efficiency is already affected in basic number processing. Overall, the neurocognitive literature suggests that (i) math anxiety elicits emotion- and pain-related activation during and before math activities, (ii) that the negative emotional response to math anxiety impairs processing efficiency, and (iii) that math deficits triggered by math anxiety may be compensated for by modulating the cognitive control or emotional regulation network. However, activation differs strongly between studies, depending on tasks, paradigms, and samples. We conclude that neural correlates can help to understand and explore the processes underlying math anxiety, but the data are not very consistent yet. PMID:26388824

  18. Neural correlates of math anxiety – An overview and implications

    Directory of Open Access Journals (Sweden)

    Christina eArtemenko

    2015-09-01

    Full Text Available Math anxiety is a common phenomenon which can have a negative impact on numerical and arithmetic performance. However, so far little is known about the underlying neurocognitive mechanisms. This mini review provides an overview of studies investigating the neural correlates of math anxiety which provide several hints regarding its influence on math performance: while behavioral studies mostly observe an influence of math anxiety on difficult math tasks, neurophysiological studies show that processing efficiency is already affected in basic number processing. Overall, the neurocognitive literature suggests that (i math anxiety elicits emotion- and pain-related activation during and before math activities, (ii that the negative emotional response to math anxiety impairs processing efficiency, and (iii that math deficits triggered by math anxiety may be compensated for by modulating the cognitive control or emotional regulation network. However, activation differs strongly between studies, depending on tasks, paradigms and samples. We conclude that neural correlates can help to understand and explore the processes underlying math anxiety, but the data are not very consistent yet.

  19. The role of self-math overlap in understanding math anxiety and the relation between math anxiety and performance

    OpenAIRE

    Necka, Elizabeth A.; Sokolowski, H. Moriah; Lyons, Ian M.

    2015-01-01

    Recent work has demonstrated that math anxiety is more than just the product of poor math skills. Psychosocial factors may play a key role in understanding what it means to be math anxious, and hence may aid in attempts to sever the link between math anxiety and poor math performance. One such factor may be the extent to which individuals integrate math into their sense of self. We adapted a well-established measure of this degree of integration (i.e., self-other overlap) to assess individual...

  20. Analyzing the Gender Gap in Math Achievement: Evidence from a Large-Scale US Sample

    Science.gov (United States)

    Cheema, Jehanzeb R.; Galluzzo, Gary

    2013-01-01

    The US portion of the Program for International Student Assessment (PISA) 2003 student questionnaire comprising of 4,733 observations was used in a multiple regression framework to predict math achievement from demographic variables, such as gender, race, and socioeconomic status, and two student-specific measures of perception, math anxiety and…

  1. The influence of experiencing success in math on math anxiety, perceived math competence, and math performance

    NARCIS (Netherlands)

    Jansen, B.R.J.; Louwerse, J.; Straatemeier, M.; van der Ven, S.H.G.; Klinkenberg, S.; van der Maas, H.L.J.

    2013-01-01

    It was investigated whether children would experience less math anxiety and feel more competent when they, independent of ability level, experienced high success rates in math. Comparable success rates were achieved by adapting problem difficulty to individuals' ability levels with a

  2. Math in Action. Hands-On, Minds-On Math.

    Science.gov (United States)

    Waite-Stupiansky, Sandra; Stupiansky, Nicholas G.

    1998-01-01

    Hands-on math must also involve students' minds in creative thinking. Math manipulatives must be used for uncovering, not just discovering. This paper presents guidelines for planning hands-on, minds-on math for elementary students. Suggestions include dialoging, questioning, integrating manipulatives and other tools, writing, and evaluating. (SM)

  3. Decontamination of latex gloves; Decontamination de gants en latex

    Energy Technology Data Exchange (ETDEWEB)

    Boutot, P; Schipfer, P; Blachere, A [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1969-07-01

    Initially the latex gloves used in controlled zones were processed after use as radioactive waste. In view of the continually increasing number used, however, the persons in charge of the SPRAR have considered the possibility of decontaminating the gloves and using them again after control. The recovery installations which have been developed were initially designed rather crudely and operated irregularly; they have been progressively improved as a result of the experience acquired; today they are more really an industrial concern, equipped with automatic machinery. In 1967 it has been possible with this set-up to recover 247000 pairs of gloves, representing nearly 70 per cent of the number treated. (author) [French] Initialement, les gants de latex utilises dans les zones controlees etaient conditionnes apres emploi comme dechets radioactifs. Mais, devant l'augmentation sans cesse croissante des quantites employees, les responsables du SPRAR ont envisage leur decontamination et leur recyclage apres controles. Les installations de recuperation mises au point, de conception artisanale et fonctionnant de maniere episodique au depart, se sont progressivement ameliorees au fur et a mesure de l'experience acquise; elles revetent aujourd'hui le caractere d'une exploitation industrielle equipee de machines automatiques. En 1967, ces nouvelles installations ont permis de recuperer 247000 paires de gants, ce qui represente pres de 70 pour cent des quantites traitees. (auteur)

  4. Math Anxiety and Math Ability in Early Primary School Years

    Science.gov (United States)

    Krinzinger, Helga; Kaufmann, Liane; Willmes, Klaus

    2010-01-01

    Mathematical learning disabilities (MLDs) are often associated with math anxiety, yet until now, very little is known about the causal relations between calculation ability and math anxiety during early primary school years. The main aim of this study was to longitudinally investigate the relationship between calculation ability, self-reported evaluation of mathematics, and math anxiety in 140 primary school children between the end of first grade and the middle of third grade. Structural equation modeling revealed a strong influence of calculation ability and math anxiety on the evaluation of mathematics but no effect of math anxiety on calculation ability or vice versa—contrasting with the frequent clinical reports of math anxiety even in very young MLD children. To summarize, our study is a first step toward a better understanding of the link between math anxiety and math performance in early primary school years performance during typical and atypical courses of development. PMID:20401159

  5. 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.

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

    NARCIS (Netherlands)

    Huijs, F; Lang, J

    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

  7. Motivation and Math Anxiety for Ability Grouped College Math Students

    Science.gov (United States)

    Helming, Luralyn

    2013-01-01

    The author studied how math anxiety, motivation, and ability group interact to affect performance in college math courses. This clarified the effects of math anxiety and ability grouping on performance. It clarified the interrelationships between math anxiety, motivation, and ability grouping by considering them in a single analysis. It introduces…

  8. Latex allergies - for hospital patients

    Science.gov (United States)

    ... ency/patientinstructions/000499.htm Latex allergies - for hospital patients To use the sharing features on this page, ... ADAM Health Solutions. About MedlinePlus Site Map FAQs Customer Support Get email updates Subscribe to RSS Follow ...

  9. Installing fonts in LaTeX a user's experience

    NARCIS (Netherlands)

    Hanssen, F.T.Y.

    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

  10. When approximate number acuity predicts math performance: The moderating role of math anxiety

    Science.gov (United States)

    Libertus, Melissa E.

    2018-01-01

    Separate lines of research suggest that people who are better at estimating numerical quantities using the approximate number system (ANS) have better math performance, and that people with high levels of math anxiety have worse math performance. Only a handful of studies have examined both ANS acuity and math anxiety in the same participants and those studies report contradictory results. To address these inconsistencies, in the current study 87 undergraduate students completed assessments of ANS acuity, math anxiety, and three different measures of math. We considered moderation models to examine the interplay of ANS acuity and math anxiety on different aspects of math performance. Math anxiety and ANS acuity were both unique significant predictors of the ability to automatically recall basic number facts. ANS acuity was also a unique significant predictor of the ability to solve applied math problems, and this relation was further qualified by a significant interaction with math anxiety: the positive association between ANS acuity and applied problem solving was only present in students with high math anxiety. Our findings suggest that ANS acuity and math anxiety are differentially related to various aspects of math and should be considered together when examining their respective influences on math ability. Our findings also raise the possibility that good ANS acuity serves as a protective factor for highly math-anxious students on certain types of math assessments. PMID:29718939

  11. When approximate number acuity predicts math performance: The moderating role of math anxiety.

    Science.gov (United States)

    Braham, Emily J; Libertus, Melissa E

    2018-01-01

    Separate lines of research suggest that people who are better at estimating numerical quantities using the approximate number system (ANS) have better math performance, and that people with high levels of math anxiety have worse math performance. Only a handful of studies have examined both ANS acuity and math anxiety in the same participants and those studies report contradictory results. To address these inconsistencies, in the current study 87 undergraduate students completed assessments of ANS acuity, math anxiety, and three different measures of math. We considered moderation models to examine the interplay of ANS acuity and math anxiety on different aspects of math performance. Math anxiety and ANS acuity were both unique significant predictors of the ability to automatically recall basic number facts. ANS acuity was also a unique significant predictor of the ability to solve applied math problems, and this relation was further qualified by a significant interaction with math anxiety: the positive association between ANS acuity and applied problem solving was only present in students with high math anxiety. Our findings suggest that ANS acuity and math anxiety are differentially related to various aspects of math and should be considered together when examining their respective influences on math ability. Our findings also raise the possibility that good ANS acuity serves as a protective factor for highly math-anxious students on certain types of math assessments.

  12. When approximate number acuity predicts math performance: The moderating role of math anxiety.

    Directory of Open Access Journals (Sweden)

    Emily J Braham

    Full Text Available Separate lines of research suggest that people who are better at estimating numerical quantities using the approximate number system (ANS have better math performance, and that people with high levels of math anxiety have worse math performance. Only a handful of studies have examined both ANS acuity and math anxiety in the same participants and those studies report contradictory results. To address these inconsistencies, in the current study 87 undergraduate students completed assessments of ANS acuity, math anxiety, and three different measures of math. We considered moderation models to examine the interplay of ANS acuity and math anxiety on different aspects of math performance. Math anxiety and ANS acuity were both unique significant predictors of the ability to automatically recall basic number facts. ANS acuity was also a unique significant predictor of the ability to solve applied math problems, and this relation was further qualified by a significant interaction with math anxiety: the positive association between ANS acuity and applied problem solving was only present in students with high math anxiety. Our findings suggest that ANS acuity and math anxiety are differentially related to various aspects of math and should be considered together when examining their respective influences on math ability. Our findings also raise the possibility that good ANS acuity serves as a protective factor for highly math-anxious students on certain types of math assessments.

  13. Radioactive iodine (125I) labeling of latex particles

    International Nuclear Information System (INIS)

    Parikh, G.C.; Ho, C.K.

    1977-01-01

    The invention disclosed in this application is directed towards developing a radioiodination method which is applicable to the labeling of 2.02 micrometer (μm) and 0.37 micrometer (μm) diameter polyvinyltoluene latex particles that have been used as an immunoadsorbent. More particularly the overall method includes using an oxidation-reduction chemical reaction for tagging latex particles. Two methods are described. One, the hydrochloric acid method; and two, the nitric acid method

  14. Rapid latex agglutination test for the serodiagnosis of human brucellosis

    NARCIS (Netherlands)

    Abdoel, Theresia H.; Smits, Henk L.

    2007-01-01

    We developed and evaluated a user-friendly latex agglutination assay for the serodiagnosis of human brucellosis. The assay was obtained by coating colored latex beads with Brucella lipopolysaccharides and drying of the activated beads onto white agglutination cards. Individual cards were sealed in a

  15. LOL2 and LOL5 loci control latex production by laticifer cells in Euphorbia lathyris.

    Science.gov (United States)

    Castelblanque, Lourdes; Balaguer, Begoña; Marti, Cristina; Orozco, Marianela; Vera, Pablo

    2018-06-07

    Laticifers are specialized plant cells capable of indefinite elongation that ramify extensively and are responsible for latex biosynthesis and accumulation. However, the mechanisms underlying laticifer cell differentiation, growth and production of latex remain largely unknown. In a search for mutants showing enhanced accumulation of latex we identified two LOT OF LATEX (LOL) loci in Euphorbia lathyris. lol2 and lol5 mutants show enhanced production of latex contained within laticifer cells. The recessive lol2 mutant carries increased biosynthesis of the plant hormone jasmonoyl-isoleucine (JA-Ile) and therefore establishes a genetic link between jasmonic acid (JA) signaling and latex production in laticifers. Instead, heightened production of latex in lol5 plants obeys to enhanced proliferation of laticifer cells. Phylogenetic analysis of laticifer-expressed genes in E. lathyris and in two other latex-bearing species, Euphorbia corallioides and Euphorbia palustris, allowed the identification of canonical JA responsive elements present in the gene promoter regions of laticifer marker genes. Moreover, we identified that the hormone JA functions not as a morphogen for laticifer differentiation but as a trigger for the fill out of laticifers with latex and the associated triterpenoids. The identification of LOL loci represents a further step towards the understanding of mechanisms controlling latex production in laticifer cells. No claim to original US Government works New Phytologist © 2018 New Phytologist Trust.

  16. Measurement of math beliefs and their associations with math behaviors in college students.

    Science.gov (United States)

    Hendy, Helen M; Schorschinsky, Nancy; Wade, Barbara

    2014-12-01

    Our purpose in the present study was to expand understanding of math beliefs in college students by developing 3 new psychometrically tested scales as guided by expectancy-value theory, self-efficacy theory, and health belief model. Additionally, we identified which math beliefs (and which theory) best explained variance in math behaviors and performance by college students and which students were most likely to have problematic math beliefs. Study participants included 368 college math students who completed questionnaires to report math behaviors (attending class, doing homework, reading textbooks, asking for help) and used a 5-point rating scale to indicate a variety of math beliefs. For a subset of 84 students, math professors provided final math grades. Factor analyses produced a 10-item Math Value Scale with 2 subscales (Class Devaluation, No Future Value), a 7-item single-dimension Math Confidence Scale, and an 11-item Math Barriers Scale with 2 subscales (Math Anxiety, Discouraging Words). Hierarchical multiple regression revealed that high levels of the newly discovered class devaluation belief (guided by expectancy-value theory) were most consistently associated with poor math behaviors in college students, with high math anxiety (guided by health belief model) and low math confidence (guided by self-efficacy theory) also found to be significant. Analyses of covariance revealed that younger and male students were at increased risk for class devaluation and older students were at increased risk for poor math confidence. (c) 2014 APA, all rights reserved.

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

    Science.gov (United States)

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

    2015-01-01

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

  18. ENHANCEMENT OF RESISTANCE TO OXIDATIVE DEGRADATION OF NATURAL RUBBER THROUGH LATEX DEGRADATION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A fully characterised natural rubber latex was subjected to mechanical degradation by stirring at intervals. The resistance to oxidative degradation of the different samples were studied by measuring the Plasticity retention indices (PRI).The results show that there is an enhancement of the PRI from 57% for the undegraded rubber to 79% for the one-hour degraded sample. Further degradation resulted in decrease of PRI as time of degradation increased. Therefore, the one-hour degraded sample is a special rubber with high oxidation resistance which is of great importance in engineering.

  19. Allergenicity of latex rubber products used in South African dental ...

    African Journals Online (AJOL)

    Fourteen latex examination gloves (powdered and non-powdered) and five dental rubber dams, representing 6 brands, from five dental academic institutions were analysed for latex allergens and total protein. Total protein content was determined using the BioRad DC protein assay kit and natural rubber allergen levels ...

  20. NMR relaxation times of natural rubber latex

    International Nuclear Information System (INIS)

    Harun, S.; Aziz, H.; Basir, Z.

    1994-01-01

    NMR relaxation times T sub 1 and T sub 2 of natural rubber latex have been measured at 25 degree C on a pulsed NMR spectrometer. The work focuses on the variation of the relaxation times with the amount of water content from 0% to 50%. The water content was adjusted by centrifuging and removing a certain amount of water from the sample. The data were analysed using a biexponential fitting procedure which yields simultaneously either T sub 1a and T sub 1b or T sub 2a and T sub 2b. The amount of solid was compared with the known amount of dry rubber content

  1. The Influence of Experiencing Success in Math on Math Anxiety, Perceived Math Competence, and Math Performance

    Science.gov (United States)

    Jansen, Brenda R. J.; Louwerse, Jolien; Straatemeier, Marthe; Van der Ven, Sanne H. G.; Klinkenberg, Sharon; Van der Maas, Han L. J.

    2013-01-01

    It was investigated whether children would experience less math anxiety and feel more competent when they, independent of ability level, experienced high success rates in math. Comparable success rates were achieved by adapting problem difficulty to individuals' ability levels with a computer-adaptive program. A total of 207 children (grades 3-6)…

  2. Comparing the level of dexterity offered by latex and nitrile SafeSkin gloves.

    Science.gov (United States)

    Sawyer, Jo; Bennett, Allan

    2006-04-01

    An increase in the occurrence of latex allergy has been concurrent with the increasing use of latex gloves by laboratory and healthcare workers. In recent years nitrile gloves have been used to replace latex gloves to prevent latex allergy. Nitrile gloves offer a comparable level of protection against chemical and biological agents and are more puncture resistant. However, if manual dexterity is compromised by nitrile gloves to a greater degree than latex then this may increase the risk of sharps injuries. The Purdue pegboard test, which measures both gross and fine finger dexterity, was used to test the dexterity levels of two glove types used at HPA CEPR; Kimberly-Clark SafeSkin nitrile and latex laboratory gloves. There was a statistically significant 8.6% increase in fine finger dexterity provided by latex compared with nitrile SafeSkin laboratory gloves but no difference in gross dexterity between the glove types. There was no significant relationship between glove dexterity and age or gender. The selection of glove size was influenced by the digit length of participants. Moreover, those with longer, thinner fingers appeared to have an advantage when using nitrile SafeSkin gloves. The level of dexterity provided by latex and nitrile SafeSkin gloves for tasks on a gross dexterity level are comparable and health workers will benefit from the non-allergenic properties of nitrile. For tasks requiring fine finger dexterity nitrile SafeSkin gloves may impede dexterity. Despite this, the degree of restriction appears to have a negligible impact on safety in this study when compared with the risk of latex sensitization and subsequent allergy. In addition to glove material, working practices must also take into account glove size, fit, grip and thickness, as these factors can all influence dexterity.

  3. Math Anxiety Is Related to Some, but Not All, Experiences with Math

    OpenAIRE

    Krystle O'Leary; Cheryll L. Fitzpatrick; Darcy Hallett

    2017-01-01

    Math anxiety has been defined as unpleasant feelings of tension and anxiety that hinder the ability to deal with numbers and math in a variety of situations. Although many studies have looked at situational and demographic factors associated with math anxiety, little research has looked at the self-reported experiences with math that are associated with math anxiety. The present study used a mixed-methods design and surveyed 131 undergraduate students about their experiences with math through...

  4. Latex glove sensitivity amongst diagnostic imaging healthcare personnel: a self-reporting investigation

    International Nuclear Information System (INIS)

    Healy, Jan; Brennan, Patrick C.; Bowden, Julie Anne

    2003-01-01

    The use of latex gloves has risen dramatically among healthcare workers resulting in an increase in the number of workers experiencing reactions to gloves. Little evidence of reactions among Irish healthcare workers is available. The current, self-reporting study investigated the prevalence to latex gloves amongst four professional groups within three Diagnostic Imaging Departments. Prevalence is similar to that demonstrated elsewhere with 18.3% of individuals expressing latex associated symptoms. Symptoms included itching and redness of hands, dry cracked skin, soreness of eyes and upper respiratory tract complaints. These results indicate that latex hypersensitivity is a real problem amongst Irish healthcare workers. This preliminary work provides the basis of a much larger controlled study currently being planned

  5. Math Anxiety, Working Memory, and Math Achievement in Early Elementary School

    Science.gov (United States)

    Ramirez, Gerardo; Gunderson, Elizabeth A.; Levine, Susan C.; Beilock, Sian L.

    2013-01-01

    Although math anxiety is associated with poor mathematical knowledge and low course grades (Ashcraft & Krause, 2007), research establishing a connection between math anxiety and math achievement has generally been conducted with young adults, ignoring the emergence of math anxiety in young children. In the current study, we explored whether…

  6. Mothers, Intrinsic Math Motivation, Arithmetic Skills, and Math Anxiety in Elementary School.

    Science.gov (United States)

    Daches Cohen, Lital; Rubinsten, Orly

    2017-01-01

    Math anxiety is influenced by environmental, cognitive, and personal factors. Yet, the concurrent relationships between these factors have not been examined. To this end, the current study investigated how the math anxiety of 30 sixth graders is affected by: (a) mother's math anxiety and maternal behaviors (environmental factors); (b) children's arithmetic skills (cognitive factors); and (c) intrinsic math motivation (personal factor). A rigorous assessment of children's math anxiety was made by using both explicit and implicit measures. The results indicated that accessible self-representations of math anxiety, as reflected by the explicit self-report questionnaire, were strongly affected by arithmetic skills. However, unconscious cognitive constructs of math anxiety, as reflected by the numerical dot-probe task, were strongly affected by environmental factors, such as maternal behaviors and mothers' attitudes toward math. Furthermore, the present study provided preliminary evidence of intergenerational transmission of math anxiety. The conclusions are that in order to better understand the etiology of math anxiety, multiple facets of parenting and children's skills should be taken into consideration. Implications for researchers, parents, and educators are discussed.

  7. Math Anxiety Is Related to Some, but Not All, Experiences with Math.

    Science.gov (United States)

    O'Leary, Krystle; Fitzpatrick, Cheryll L; Hallett, Darcy

    2017-01-01

    Math anxiety has been defined as unpleasant feelings of tension and anxiety that hinder the ability to deal with numbers and math in a variety of situations. Although many studies have looked at situational and demographic factors associated with math anxiety, little research has looked at the self-reported experiences with math that are associated with math anxiety. The present study used a mixed-methods design and surveyed 131 undergraduate students about their experiences with math through elementary school, junior high, and high school, while also assessing math anxiety, general anxiety, and test anxiety. Some reported experiences (e.g., support in high school, giving students plenty of examples) were significantly related to the level of math anxiety, even after controlling for general and test anxiety, but many other factors originally thought to be related to math anxiety did not demonstrate a relation in this study. Overall, this study addresses a gap in the literature and provides some suggestive specifics of the kinds of past experiences that are related to math anxiety and those that are not.

  8. Math Anxiety Is Related to Some, but Not All, Experiences with Math

    Directory of Open Access Journals (Sweden)

    Krystle O'Leary

    2017-12-01

    Full Text Available Math anxiety has been defined as unpleasant feelings of tension and anxiety that hinder the ability to deal with numbers and math in a variety of situations. Although many studies have looked at situational and demographic factors associated with math anxiety, little research has looked at the self-reported experiences with math that are associated with math anxiety. The present study used a mixed-methods design and surveyed 131 undergraduate students about their experiences with math through elementary school, junior high, and high school, while also assessing math anxiety, general anxiety, and test anxiety. Some reported experiences (e.g., support in high school, giving students plenty of examples were significantly related to the level of math anxiety, even after controlling for general and test anxiety, but many other factors originally thought to be related to math anxiety did not demonstrate a relation in this study. Overall, this study addresses a gap in the literature and provides some suggestive specifics of the kinds of past experiences that are related to math anxiety and those that are not.

  9. Radiation vulcanization of natural rubber latex with low energy accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Emdadul; Makuuchi, Keizo; Ikeda, Kenichi; Yoshii, Fumio; Kume Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Mitomo, Hiroshi [Gunma Univ., Faculty of Engineering, Department of Biological and Chemical Engineering, Kiryu, Gunma (Japan)

    2001-03-01

    The radiation vulcanization of natural rubber latex (RVNRL) with the recently installed electron beam (EB) pilot plant at Takasaki Radiation Chemistry Research Establishment, Takasaki, Japan has been discussed. The accelerating voltage and beam current of the plant are 250 kV and 10 mA respectively. The plant has a reaction vessel with the capacity of 18 liters latex to irradiate at a time. In order to obtain a suitable setting of experimental for RVNRL under EB of the plant the parameters such as irradiation time, defoamer concentration, volume of latex, beam current etc. are being optimized by varying the individual parameter at a constant set of the other variables. (author)

  10. Latex-modified fiber-reinforced concrete bridge deck overlay : construction/interim report.

    Science.gov (United States)

    1993-06-01

    Latex-modified concrete (LMC) is Portland cement concrete (PCC) with an admixture of latex. LMC is considered to be nearly impermeable to chlorides and is extensively used to construct bridge deck overlays. Unfortunately, some of these overlays have ...

  11. The Influence of Math Anxiety, Math Performance, Worry, and Test Anxiety on the Iowa Gambling Task and Balloon Analogue Risk Task.

    Science.gov (United States)

    Buelow, Melissa T; Barnhart, Wesley R

    2017-01-01

    Multiple studies have shown that performance on behavioral decision-making tasks, such as the Iowa Gambling Task (IGT) and Balloon Analogue Risk Task (BART), is influenced by external factors, such as mood. However, the research regarding the influence of worry is mixed, and no research has examined the effect of math or test anxiety on these tasks. The present study investigated the effects of anxiety (including math anxiety) and math performance on the IGT and BART in a sample of 137 undergraduate students. Math performance and worry were not correlated with performance on the IGT, and no variables were correlated with BART performance. Linear regressions indicated math anxiety, physiological anxiety, social concerns/stress, and test anxiety significantly predicted disadvantageous selections on the IGT during the transition from decision making under ambiguity to decision making under risk. Implications for clinical evaluation of decision making are discussed. © The Author(s) 2015.

  12. Modern maths

    CERN Multimedia

    Thom,R

    1974-01-01

    Le Prof. R. Thom expose ses vues sur l'enseignement des mathématiques modernes et des mathémathiques de toujours. Il est un grand mathématicien et était professeur à Strasbourg; maintenant il est professeur de hautes études scientifiques et était invité par le Prof. Piaget à Genève

  13. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Maths in Prison

    Directory of Open Access Journals (Sweden)

    Catherine Patricia Byrne

    2015-08-01

    Full Text Available I teach maths to all levels in an adult male remand prison in Ireland and am also studying for a PhD in maths in prison education in Dublin Institute of Technology (DIT. This paper describes recent initiatives piloted by maths teachers and school management to increase attendance, engagement and certification in maths. It assesses the effects of the initiatives and looks at future potential in this setting and in others. To set the paper in context, I begin by describing a typical day as a prison maths teacher.

  15. Mothers, Intrinsic Math Motivation, Arithmetic Skills, and Math Anxiety in Elementary School

    Science.gov (United States)

    Daches Cohen, Lital; Rubinsten, Orly

    2017-01-01

    Math anxiety is influenced by environmental, cognitive, and personal factors. Yet, the concurrent relationships between these factors have not been examined. To this end, the current study investigated how the math anxiety of 30 sixth graders is affected by: (a) mother’s math anxiety and maternal behaviors (environmental factors); (b) children’s arithmetic skills (cognitive factors); and (c) intrinsic math motivation (personal factor). A rigorous assessment of children’s math anxiety was made by using both explicit and implicit measures. The results indicated that accessible self-representations of math anxiety, as reflected by the explicit self-report questionnaire, were strongly affected by arithmetic skills. However, unconscious cognitive constructs of math anxiety, as reflected by the numerical dot-probe task, were strongly affected by environmental factors, such as maternal behaviors and mothers’ attitudes toward math. Furthermore, the present study provided preliminary evidence of intergenerational transmission of math anxiety. The conclusions are that in order to better understand the etiology of math anxiety, multiple facets of parenting and children’s skills should be taken into consideration. Implications for researchers, parents, and educators are discussed. PMID:29180973

  16. Mothers, Intrinsic Math Motivation, Arithmetic Skills, and Math Anxiety in Elementary School

    Directory of Open Access Journals (Sweden)

    Lital Daches Cohen

    2017-11-01

    Full Text Available Math anxiety is influenced by environmental, cognitive, and personal factors. Yet, the concurrent relationships between these factors have not been examined. To this end, the current study investigated how the math anxiety of 30 sixth graders is affected by: (a mother’s math anxiety and maternal behaviors (environmental factors; (b children’s arithmetic skills (cognitive factors; and (c intrinsic math motivation (personal factor. A rigorous assessment of children’s math anxiety was made by using both explicit and implicit measures. The results indicated that accessible self-representations of math anxiety, as reflected by the explicit self-report questionnaire, were strongly affected by arithmetic skills. However, unconscious cognitive constructs of math anxiety, as reflected by the numerical dot-probe task, were strongly affected by environmental factors, such as maternal behaviors and mothers’ attitudes toward math. Furthermore, the present study provided preliminary evidence of intergenerational transmission of math anxiety. The conclusions are that in order to better understand the etiology of math anxiety, multiple facets of parenting and children’s skills should be taken into consideration. Implications for researchers, parents, and educators are discussed.

  17. Antimalarial Anthrone and Chromone from the Leaf Latex of Aloe ...

    African Journals Online (AJOL)

    In Ethiopian traditional medicine, the leaf latex of Aloe debranan Chrstian is used for the treatment of several diseases including malaria. In an ongoing search for effective, safe and cheap antimalarial agents from plants, the leaf latex of A. debrana was tested for its in vivo antimalarial activity, in a 4-day suppressive assay ...

  18. Polylactide/Montmorillonite Hybrid Latex as a Barrier Coating for Paper Applications

    Directory of Open Access Journals (Sweden)

    Davide Bandera

    2016-03-01

    Full Text Available We developed a paper coating for the potential application in food packaging based on polylactide and montmorillonite. It is applied to the paper in the form of a stable, water-based latex with a solid content of 25–28 wt %. The latex is prepared from a commercially available polylactide, surfactants, montmorillonite, a plasticizer, chloroform (to be removed later and water by an emulsion/solvent evaporation procedure. This coating formulation is applied to the paper substrate by bar-coating, followed by hot-pressing at 150 °C. The coated papers achieved up to an 85% improvement in water vapor transmission rates when compared to the pristine papers. The coating latex is prepared from inexpensive materials and can be used for a solvent-free coating process. In addition, the ingredients of the latex are non-toxic; thus, the coated papers can be safely used for food packaging.

  19. Relationships between Cattell-Horn-Carroll (CHC) Cognitive Abilities and Math Achievement within a Sample of College Students with Learning Disabilities

    Science.gov (United States)

    Proctor, Briley

    2012-01-01

    This study examined the relationship between cognitive abilities and math achievement within a sample of college students with learning disabilities (LD). The cognitive abilities were seven areas identified by Stratum II of the Cattell-Horn-Carroll (CHC) theory of cognitive abilities, in addition to the eighth area of Working Memory. Math…

  20. Study of Antibacterial Activity and Bacteriology of Latex from Asclepias syriaca L

    Science.gov (United States)

    McCay, Steven; Mahlberg, Paul

    1973-01-01

    Whole and fractionated latex of Asclepias syriaca was tested for antimicrobial or growth-promoting activity with 16 genera and species of bacteria. Latex and extracted fractions (distilled water, acetic acid, sodium bicarbonate, sulfuric acid, and ethyl ether) possessed no detectable antimicrobial activity. Comparison of growth curves of selected bacteria incubated with serum and rubber fractions, as well as controls, revealed no detectable inhibition of growth, except for a slight inhibitory response to autoclaved serum. Most bacteria were capable of utilizing latex for a substrate as indicated by the increased growth rate in the exponential phase. The stationary phase was entered simultaneously by both the treated cultures and the controls. Various bacteria cultured in a litmus latex mixture yielded populations which ranged from <104 organisms/ml for Lactobacillus casei, Staphylococcus aureus and Micrococcus lysodeikticus to 1.1 × 1010 organisms/ml for Clostridium acetobutylicum. Whole latex, as well as the serum and rubber fractions, support the growth of various bacteria, but under field conditions there is no evidence for systemic infection of this type of cell by bacteria. PMID:4790590

  1. The relation between math self-concept, test and math anxiety, achievement motivation and math achievement in 12 to 14-year-old typically developing adolescents

    OpenAIRE

    Timmerman, H.L.; Toll, S.W.M.; van Luit, J.E.H.

    2017-01-01

    :This study examines the relation between math self-concept, test and math anxiety, achievement motivation, and math achievement in typically developing 12 to 14-year-old adolescents (N = 108) from a school for secondary education in the Netherlands. Data was obtained using a math speed test, achievement motivation test, and the math experience questionnaire. A significant positive correlation was found between math self-concept and math achievement in all four math domains (measurement, rela...

  2. High concentrations of natural rubber latex allergens in gloves used ...

    African Journals Online (AJOL)

    Introduction. Gloves made of natural rubber latex (NRL) are commonly used by healthcare workers because of their good qualities. However, allergic reactions to latex allergens are still commonly reported. Objective. To measure the concentrations of Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02 allergens in gloves used by a ...

  3. Application of radiation vulcanized natural rubber latex in Indonesia

    International Nuclear Information System (INIS)

    Soebianto, Y.S.; Wiwik Sofiarti; Razzak, M.T.

    1996-01-01

    The center has carried out R and D of Radiation Vulcanization Natural Rubber Latex (RVNRL) technology and introduced it to the industries since the inauguration and operation of the latex pilot plant in 1983. After years of experiences and the environmental consideration, n-butylacrylate (n-BA) has replaced CCI, as the sensitizer. Until now the introduction program shows that radiation vulcanized latex is more suitable for home industries than large industries. The obstacle of the program is the marketing of the dipped products. In spite of these problems, the introduction of this technology to the people in some undeveloped area of Java has supported the national program to improve their living standard. The problems of nitrosamine and protein allergic have turn up RVNRL to be the substitute of sulfur vulcanized latex in the future. The cooperation with a national condom manufacturer (PT Mitra Banjaran) has applied RVNRL for condom production in the large scale. Soft condoms with less probability of pinhole are obtained, but the technical problem is stickiness after pilling. Supply to a baby teat and a rubber thread manufacturer offers great advantages by not using any chemicals. In spite of the advantages, the problem of latex viscosity for dipping and the low modulus of elasticity of the threads arise. Through those input CAIR-BATAN is conducting the research and development in improving the crosslinking among the rubber particles that are supposed to be the reason of the stickiness and low modulus of elasticity. This effort is expected to be able to broaden the application of RVNRL, and it will be achieved only by the involvement of rubber chemist, rubber technologist, and radiation chemist

  4. 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.

  5. Pilot scale experiments on radiation vulcanization of NR latex

    International Nuclear Information System (INIS)

    Ridwan, M.

    1985-01-01

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

  6. Molluscicidal effect of Euphorbia umbellata (Pax Bruyns latex on Biomphalaria glabrata, Schistosoma mansoni host snail

    Directory of Open Access Journals (Sweden)

    Luciana Patrícia Lima Alves Pereira

    2017-12-01

    Full Text Available ABSTRACT Euphorbia umbellata (Pax Bruyns is an easily cultivated shrub, with occurrence in the tropical regions of the American and African continents. Chemical studies have revealed that the latex of this plant is rich in terpene compounds, which are highly toxic to snails Biomphalaria glabrata (Basommatophora: Planorbidae. The aim of this study was to evaluate the chemical composition and molluscicidal activity of the latex produced by E. umbellata, as well as the safety of its application in aquatic environments. The concentration of latex that killed 90% of the exposed snails after 24 h exposure (LC90 was 3.69 mg/L. Toxicity bioassays using Danio rerio (zebrafish revealed that these animals were less susceptible to latex than planorbids. However, it is important to perform other toxicity tests to ensure the feasibility of using latex to control populations of mollusks that contribute to schistosomiasis transmission. A phytochemical screening performed with the E. umbellata latex identified the triterpenoid and coumarin class. Further studies are warranted to isolate, identify, and test the active compounds of E. umbellata latex in B. glabrata.

  7. Study on irradiation condition in radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    Zhu Nankang; Wang Chunlei; Makuuchi, K.; Yoshii, F.

    1996-01-01

    The effect of gamma rays irradiation dose rates on RVNRL preparation was studied using Malaysian latex added with O.2 phr of KOH and 5 phr n-BA. The results showed, to ensure the tensile strength of the latex film meet the requirement, when applying vulcanisation doses, Dv of 20 kGy 20 and 15 kGy, irradiation dose rates should not be greater than 0. 49 kGy/hr and 1. 6 kGy/hr respectively. Its was found that within the storage time of 20 days there was no change in the physical properties of the latex films

  8. Respiratory and dermal symptoms in Thai nurses using latex products.

    Science.gov (United States)

    Supapvanich, C; Povey, A C; de Vocht, F

    2013-09-01

    Despite known health risks related to the use of powdered latex gloves (PLGs), they are still widely used in hospitals in developing countries due to the high cost of alternatives. To determine the prevalence of dermal and respiratory symptoms associated with latex glove use in nurses in Thailand and evaluate the influence of previously reported occupational risk factors in this population. A cross-sectional study in female nurses working in three Thai hospitals. Participants completed a questionnaire on demographics, occupational and personal history, use of latex products at work and dermal and respiratory symptoms attributed to occupational use of latex gloves. Of 899 nurses, 18% reported health effects attributed to the use of latex products. After adjustment for confounding, occupational risk factors associated with increased reporting of dermal symptoms included wearing more than 15 pairs of PLG per day (odds ratio (OR): 2.10, 95% confidence interval (CI): [1.32-3.34]), using chlorhexidine (OR: 2.07, 95% CI: [1.22-3.52]) and being an operating theatre nurse (OR: 2.46, 95% CI: [1.47-4.12]). Being a labour ward nurse (OR: 3.52, 95% CI: [1.26-9.85]) was the only factor associated with increased reporting of respiratory symptoms. Continuing use of PLGs in Thai nurses is associated with increased prevalence of dermal symptoms compared with data from developed countries. Measures to reduce such health effects are well established and should be considered. Additionally, replacement of chlorhexidine with an alternative detergent seems advisable.

  9. Aggregation and charging of sulfate and amidine latex particles in the presence of oxyanions.

    Science.gov (United States)

    Sugimoto, Takuya; Cao, Tianchi; Szilagyi, Istvan; Borkovec, Michal; Trefalt, Gregor

    2018-08-15

    Electrophoretic mobility and time resolved light scattering are used to measure the effect on charging and aggregation of amidine and sulfate latex particles of different oxyanions namely, phosphate, arsenate, sulfate, and selenate. In the case of negatively charged sulfate latex particles oxyanions represent the coions, while they represent counterions in the case of the positively charged amidine latex. Repulsive interaction between the sulfate latex surface and the coions results in weak ion specific effects on the charging and aggregation. On the other hand the interaction of oxyanions with the amidine latex surface is highly specific. The monovalent dihydrogen phosphate ion strongly adsorbs to the positively charged surface and reverses the charge of the particle. This charge reversal leads also to the restabilization of the amidine latex suspension at the intermediate phosphate concentrations. In the case of dihydrogen arsenate the adsorption to amidine latex surface is weaker and no charge reversal and restabilization occurs. Similar differences are seen between the sulfate and selenate analogues, where selenate adsorbs more strongly to the surface as compared to the sulfate ion and invokes charge reversal. The present results indicate that ion specificity is much more pronounced in the case of counterions. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Managing latex allergies at home

    Science.gov (United States)

    ... Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School, Washington, DC. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Related MedlinePlus Health Topics Latex Allergy Browse the Encyclopedia A.D.A. ...

  11. Biochemical and microstructural characteristics of meat samples ...

    African Journals Online (AJOL)

    This study was conducted to compare the efficiency of different plant proteases for changing biochemical and microstructural characteristics in muscle foods. The meat samples from chicken, giant catfish, pork and beef were treated with four types of proteolytic enzymes: Calotropis procera latex proteases, papaya latex ...

  12. Effect of heterogeneous distribution of crosslink density on physical properties of radiation vulcanized NR (Natural Rubber) latex film

    International Nuclear Information System (INIS)

    Keizo Makuuchi; Fumio Yoshii; Miura, H.; Murakami, K.

    1996-01-01

    Thus a study has been carried out to investigate the effect of particle to particle variation in crosslink density on physical properties of radiation vulcanized NR latex film. NR latex was irradiated in small bottle by γ rays without vulcanization accelerator to provide latex rubber particles having homogeneous distribution of crosslink density. The doses were 30, 50, 100, 250, 300, 400, 500 and 600 kGy. Weight swelling ratio, gel fraction, tensile strength and elongation at break of the latex film from the mixed latex were measured. The vulcanization dose of this latex was 250 kGy. Then the two different latexes were mixed in a such way to adjust the average dose of 250 kGy to prepare a latex consisting of rubber particles having heterogeneous distribution of crosslink density. Tensile strength of the latex film was depressed by mixing. The reduction increased with increasing the decrease of gel fraction by mixing. However the reduction was not serious when the dose difference of two latexes was less than 200 kGy

  13. Radiation vulcanization of natural rubber latex using irradiation n-butyl acrylate aqueous emulsion as sensitizer

    International Nuclear Information System (INIS)

    Vo Van Thien; Nguyen Quoc Hien; Keizo Makuuchi; Fumio Yoshii

    2000-01-01

    Natural rubber latex was vulcanized by gamma radiation with n-butyl acrylate aqueous emulsion irradiated at dose of 1.5 kGy as sensitizer. The total solid content of latex increases on the irradiation dose. The viscosity of latex on the standing time was investigated and became stable after one month of storage. The gel content of latex films increasing with irradiation dose and attained more than 94% at dose of 10 kGy. Tensile strength of films reached the values of 31MPa; 30 Mpa and 25 Mpa at vulcanization doses of 20 kGy, 15 kGy and 8 kGy for the concentrations of sensitizer 7 phr, 9 phr and 13 phr respectively. Elongation at break decreases as increasing dose. Tear strength of rubber films was from 30-40 N/mm. The tackiness of latex films decreases and smell of vulcanized latex is almost negligible. (author)

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

    Directory of Open Access Journals (Sweden)

    Ying Nie

    2008-03-01

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

  15. The Groove of Growth: How Early Gains in Math Ability Influence Adolescent Achievement

    Science.gov (United States)

    Watts, Tyler W.; Duncan, Greg J.; Siegler, Robert S.; Davis-Kean, Pamela E.

    2014-01-01

    A number of studies, both small scale and of nationally-representative student samples, have reported substantial associations between school entry math ability and later elementary school achievement. However, questions remain regarding the persistence of the association between early growth in math ability and later math achievement due to the…

  16. Progress in radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    Makuuchi, Keizo

    2000-01-01

    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)

  17. Extractable protein of radiation vulcanized natural rubber latex

    International Nuclear Information System (INIS)

    Soebianto, Y.S.; Ratnayake, U.M.; Makuuchi, Keizo; Yoshii, Fumio; Kume, Tamikazu

    2000-01-01

    Protein remained in the latex products are reported to cause serious allergy. 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) in three different processes. The amount of WSP was 3 phr. It was only added to RVNRL (standard), added to re-centrifuged RVNRL (pre-centrifugation), and added to RVNRL followed by centrifugation (post-centrifugation). The protein content was determined by enhanced BCA method, and identified by SDS-PAGE. Extractable protein (EP) from the rubber has been reduced up to the minimum protein detection by combining WSP addition and centrifugation. Short leaching time (20-30 min.) can be achieved after the combine treatment, and SDS-PAGE 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 efficiency of protein removal by WSP depends on its molecular weight of WSP which relates to its water solubility. (author)

  18. Improving of Water Resistance of Asphalt Concrete Wearing Course Using Latex-Bitumen Binder

    Directory of Open Access Journals (Sweden)

    Siswanto Henri

    2017-01-01

    Full Text Available It is well known that presence of water in a bituminous mix is a critical factor which can lead to premature failure of flexible pavements. This requires solutions one of which is to formulate an asphalt mix that has a high resistance to moisture and one way to do this is to mix latex with the asphalt mix. The purpose of this experimental study was to investigate the effect of water on Marshall stability of asphalt concrete wearing course (ACWC made with a latex-bitumen binder. Latex-bitumen was mixed with aggregate and four levels of latex content were investigated in this study, namely, 0%, 2%, 4% and 6% respectively by weight of asphalt. Wet procces was used in the blending of mixtures. The procedure used to obtain the optimum binder contents conformed to the Marshall procedure (SNI 06-2489-1991. Six Marshall specimens at optimum binder content were prepared for each binder mix investigated. Three of six specimens from each group were tested under Marshall standards. The remaining specimens were tested by immersion in a bath at 60°C for 24 hours. The Marshall index of retained stability was used to evaluate the effect of water on the Marshall stability of ACWC. The results indicated that the addition of up to 4% latex to ACWC mix increased the retained Marshall stability, whereas the addition of latex above 4% decreased the retained stability of the mixture. The addition of 4% CRM significantly improved the retained stability of the mixture and was the best latex – ACWC mix.

  19. 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.

  20. Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser.

    Science.gov (United States)

    Shiraz, Hana; Peake, Simon J; Davey, Tim; Cameron, Neil R; Tabor, Rico F

    2018-05-15

    Film-forming polymer latex particles of diameter acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. Results indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Synthesis of polymer hybrid latex poly(methyl methacrylate-co-butyl acrylate) with organo montmorillonite via miniemulsion polymerization method for barrier paper

    Science.gov (United States)

    Chanra, J.; Budianto, E.; Soegijono, B.

    2018-03-01

    Hybrid polymer latex based on combination of organic-inorganic materials, poly(methyl methacrylate-co-butyl acrylate) (PMMBA) and organo-montmorillonite (OMMT) were synthesized via miniemulsion polymerization technique. Modification of montmorillonite (MMT) through the incorporation of myristyltrimethylammonium bromide (MTAB) into the clay’s interlayer spaces were investigated by Small-Angle X-ray Scattering (SAXS), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). Barrier property and thermal stability of polymer latex film sample were investigated through its Water Vapor Transmission Rate (WVTR) and Thermogravimetric Analysis (TGA). The results indicated that addition of OMMT as filler in PMMBA increased the barrier property and thermal stability of the latex film. Addition of 8.0% (wt) OMMT increased the barrier property and thermal stability. Miniemusion polymerization process with higher addition (>8.0 wt%) of OMMT resulting in high latex viscosity, particle size, and high amount of coagulum. The utilization of this hybrid polymer could benefits paper and board industries to produce high quality barrier paper for food packaging.

  2. Science and technology of rubber reclamation with special attention to NR based waste latex products

    NARCIS (Netherlands)

    Rajan, V.V.; Dierkes, Wilma K.; Joseph, R.; Noordermeer, Jacobus W.M.

    2006-01-01

    A comprehensive overview of reclamation of cured rubber with special emphasis on latex reclamation is depicted in this paper. The latex industry has expanded over the years to meet the world demands for gloves, condoms, latex thread, etc. Due to the strict specifications for the products and the

  3. Evaluation of force degradation characteristics of orthodontic latex elastics in vitro and in vivo.

    Science.gov (United States)

    Wang, Tong; Zhou, Gang; Tan, Xianfeng; Dong, Yaojun

    2007-07-01

    To evaluate the characteristics of force degradation of latex elastics in clinical applications and in vitro studies. Samples of 3/16-inch latex elastics were investigated, and 12 students between the ages of 12 and 15 years were selected for the intermaxillary and intramaxillary tractions. The elastics in the control groups were set in artificial saliva and dry room conditions and were stretched 20 mm. The repeated-measure two-way analysis of variance and nonlinear regression analysis were used to identify statistical significance. Overall, there were statistically significant differences between the different methods and observation intervals. At 24- and 48-hour time intervals, the force decreased during in vivo testing and in artificial saliva (P .05). In intermaxillary traction the percentage of initial force remaining after 48 hours was 61%. In intramaxillary traction and in artificial saliva the percentage of initial force remaining was 71%, and in room conditions 86% of initial force remained. Force degradation of latex elastics was different according to their environmental conditions. There was significantly more force degradation in intermaxillary traction than in intramaxillary traction. The dry room condition caused the least force loss. There were some differences among groups in the different times to start wearing elastics in intermaxillary traction but no significant differences in intramaxillary traction.

  4. Preliminary study of semi-refined carrageenan (SRC) as secondary gelling agent in natural rubber (NR) latex foam

    Science.gov (United States)

    Norhazariah, S.; Azura, A. R.; Azahari, B.; Sivakumar, R.

    2017-12-01

    Semi-refined carrageenan (SRC) product is considerably cheaper and easier to produce as a natural polysaccharide, which was utilized in food and other product application. However, the application in latex is limited. The aim of this work is to evaluate the SRC produced from low industrial grade seaweed (LIGS) in the latex foam application. The FTIR spectra showed the SRC produced as kappa type carrageenan with lower sulfur content compared to native LIGS. NR latex foam is produced by using the Dunlop method with some modifications. The effect of SRC loading as a secondary gelling agent in NR latex foam is investigated. The density and morphology of the NR latex foam with the addition of the SRC are analyzed. NR latex foam density increased with SRC loading and peaked at 1.8 phr SRC. The addition of SRC has induced the bigger cell size compared to the cell size of the control NR latex foam, as shown in the optical micrograph. It can be concluded that SRC LIGS could be acted as secondary gelling agent in NR latex foam.

  5. Radiation vulcanization of natural rubber latex (NRL) using low energy electron beam accelerator

    International Nuclear Information System (INIS)

    Feroza Akhtar; Keizo Makuuchi; Fumio Yoshii

    1996-01-01

    The electron beam induced vulcanization of natural rubber latex has been studied using low energy Electron Beam (EB) accelerators of 300, 250 and 175 keV ne latex was irradiated in a special type stainless steel reaction reactor with a stirrer at the bottom of the reactor. From the results it was found that 300 and 250 keV accelerators could effectively vulcanize NRL. But accelerator of 175 keV is too low energy to vulcanize the latex. At the same time a drum type irradiator where thin layer of NRL was irradiated by accelerator, was used for vulcanization of NRL. This type of irradiator also showed good physical properties of vulcanized latex. The effects of beam current and stirrer speed on vulcanization were studied

  6. The physicochemical quality and meat microstructure of post laying hen with addition of Biduri (Calotropis gigantea) latex extract

    Science.gov (United States)

    Nuhriawangsa, A. M. P.; Hertanto, B. S.; Kartikasari, L. R.; Swastike, W.; Cahyadi, M.; Rasid, S.

    2018-01-01

    The objective of this study was to evaluate the effect of extract level of Biduri latex on the meat quality of laying hens. The materials of this research were Biduri latex and thigh meat from hens strain Lohman. The latex was tapped from a young tissue stem and centrifuged for its supernatant. Meats were smeared with latex, punctured and incubated for 30 minutes. Concentrations of latex were 0, 3, 6 and 9% from the weight of meat (w/w). The variables were water, dissolved protein, crude fat content, tenderness and microstructure of meat. The statistical analysis method using ANOVA and if there was a mean difference, Duncan test was used. Descriptive analysis was used for microstructures of meat by comparing its hydrolysis conditions. The study showed that fat had significant difference (P meat structure. The fat content increased with addition of 3% latex. The value of dissolved protein increased but tenderness decreased by addition extract of 6% latex. The addition of Biduri latex extract showed that hydrolysis in the microstructure of meat. The addition of 6% latex was the best meat quality.

  7. Effects of sulfur-based hemostatic agents and gingival retraction cords handled with latex gloves on the polymerization of polyvinyl siloxane impression materials

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Palhares Machado

    2011-12-01

    Full Text Available OBJECTIVES: This study investigated the possible interactions between three addition silicone materials (Express®, Aquasil Ultra® and Adsil®, three hemostatic agents (ferric sulfate, StatGel FS®; aluminum sulfate, GelCord®; and aluminum chloride, Hemostop® and gingival retraction cords previously handled with latex gloves to determine whether direct contact with medicaments or indirect contamination by latex in conditions similar to those found in clinical practice inhibit or affect the setting of the impression materials. MATERIAL AND METHODS: A portable device for the simultaneous test of several specimens was specifically developed for this study. Polymerization inhibition was analyzed by examination of the impressions and the molded surface. Ten trials were performed for each addition silicone material used in the study, at a total of 240 study samples. RESULTS: All the samples tested (N=240 were nonreactive regardless of the type of combination used. CONCLUSIONS: Aluminum sulfate, ferric sulfate and aluminum chloride hemostatic solutions did not show any inhibitory potential on the addition silicone samples under study, and there were no changes in polymerization as a result of contact between addition silicone and retraction cords handled with latex gloves.

  8. Effects of sulfur-based hemostatic agents and gingival retraction cords handled with latex gloves on the polymerization of polyvinyl siloxane impression materials.

    Science.gov (United States)

    Machado, Carlos Eduardo Palhares; Guedes, Carlos Gramani

    2011-01-01

    This study investigated the possible interactions between three addition silicone materials (Express®, Aquasil Ultra® and Adsil®), three hemostatic agents (ferric sulfate, StatGel FS®; aluminum sulfate, GelCord®; and aluminum chloride, Hemostop®) and gingival retraction cords previously handled with latex gloves to determine whether direct contact with medicaments or indirect contamination by latex in conditions similar to those found in clinical practice inhibit or affect the setting of the impression materials. A portable device for the simultaneous test of several specimens was specifically developed for this study. Polymerization inhibition was analyzed by examination of the impressions and the molded surface. Ten trials were performed for each addition silicone material used in the study, at a total of 240 study samples. All the samples tested (N=240) were nonreactive regardless of the type of combination used. Aluminum sulfate, ferric sulfate and aluminum chloride hemostatic solutions did not show any inhibitory potential on the addition silicone samples under study, and there were no changes in polymerization as a result of contact between addition silicone and retraction cords handled with latex gloves.

  9. 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.

  10. Maths in Prison

    OpenAIRE

    Catherine Patricia Byrne

    2015-01-01

    I teach maths to all levels in an adult male remand prison in Ireland and am also studying for a PhD in maths in prison education in Dublin Institute of Technology (DIT). This paper describes recent initiatives piloted by maths teachers and school management to increase attendance, engagement and certification in maths. It assesses the effects of the initiatives and looks at future potential in this setting and in others. To set the paper in context, I begin by describing a typical day as a ...

  11. Maths in Prison

    OpenAIRE

    Byrne, Catherine; Carr, Michael

    2015-01-01

    I teach maths to all levels in an adult male remand prison in Ireland and am also studying for a PhD in maths in prison education in Dublin Institute of Technology (DIT). This paper describes recent initiatives piloted by maths teachers and school management to increase attendance, engagement and certification in maths. It assesses the effects of the initiatives and looks at future potential in this setting and in others. To set the paper in context, I begin by describing a typical day as a p...

  12. A simple kit for rapid field diagnosis of potato virus Y by latex serological test

    Directory of Open Access Journals (Sweden)

    Aarne Kurppa

    1987-07-01

    Full Text Available A simple kit for rapid detection of potato virus Y by latex serological test was developed. The test is carried out on a white cardboard sheet and the results can be read by naked eye in two minutes. A test card of 10 x 6 cm holds latex sensitized antibodies, buffers and other necessary ingredients as dry blue colored formulate on the ringed areas of the card. A test card includes space for six tests and positive and negative controls. The kit also includes disposable plastic sticks for mixing the samples with test reagents and a hand press with disposable plastic tips. For testing, dried reagents are dissolved in drops of sample and mixed. After gentle rotation, samples containing virus appear clearly granulated while samples from healthy plants remain unagglutinated. The testing of undiluted extracts of evenly developed tuber sprouts resulted in over 91 % identity with the results obtained with ELISA that was used as a control method. Testing of diluted leaf extracts reached the same reliability but undiluted leaf extracts from glasshouse grown potatoes were not well suitable as test samples because of their dark green color. No such problems occurred with field grown material and a complete identity with the ELISA readings was true when the samples included secondarily infected potato plants. No reaction to other potato viruses than PVY was obtained by the test kit.

  13. Advanced Math Equals Career Readiness. Math Works

    Science.gov (United States)

    Achieve, Inc., 2013

    2013-01-01

    The equation is simple: No matter their background, students who take challenging math courses in high school get better jobs and earn more money throughout their entire lives. This paper stresses that: (1) Higher-level math opens doors for any and all postsecondary programs and keeps it open for advancement beyond entry-level jobs; and (2)…

  14. Preparation of composites of national rubber latex (NRL) - portland cement mould. Vol. 3

    International Nuclear Information System (INIS)

    Dessouki, A.M.; Taher, N.H.; El-Nahas, H.H.

    1996-01-01

    The aim of this study is to prepare some polymeric mould using national rubber latex (NRL) - portland cement composites based on a delayed- action mechanism. Factors affecting the preparation process such as concentration, mixing percentage, additives and their effect on what is regarded as a delayed action coacervant combination was studied. Composites of national latex (NRL) - portland cement would were prepared as two separate parts. The stabilized natural rubber latex (NRL) 100 parts with hydroxy ethyl cellulose (HEC) 2 parts as stabilizer and a delayed - action coacervant (sodium meta silicate as a delaying agent) 5 parts on one hand and the dry blend of cement 65 parts soluble in 65 parts of water as a paste on the other hand were mixed thoroughly on site. (HEC) was added to the rubber latex to prevent the coagulation of the rubber latex with the electrolyte (sodium meta silicate) present in the rubber mixture. Two kinds of stabilization occurred in the rubber part, namely steric stabilization and the stabilization against electrolyte. The effect of delayed - action coacervant (sodium meta silicate) on the initial setting time of rubber - cement mould showed that the molding process did not occur at sodium meta silicate concentration less than 2.66 parts per 100 parts of rubber latex (phr), and the optimum concentration used was 5% parts of rubber latex. It was observed that addition of a delaying agent (Sodium meta silicate) to the rubber part enhanced the delaying mechanism in the time needed for the molding process, while the addition of the delaying agent to the cement part did not have any effect on retardation of the molding process. Chemical coacervants function mainly by reducing the ζ potential which is associated with the electrical double layer surrounding the latex particle. This reduction may brought about in at least three distinct ways which take place in the system studied. 5 figs., 3 tabs

  15. Preparation of composites of national rubber latex (NRL) - portland cement mould. Vol. 3

    Energy Technology Data Exchange (ETDEWEB)

    Dessouki, A M; Taher, N H; El-Nahas, H H [National Center for Radiation Research and Technology, Atomic Energy Athority, Cairo (Egypt)

    1996-03-01

    The aim of this study is to prepare some polymeric mould using national rubber latex (NRL) - portland cement composites based on a delayed- action mechanism. Factors affecting the preparation process such as concentration, mixing percentage, additives and their effect on what is regarded as a delayed action coacervant combination was studied. Composites of national latex (NRL) - portland cement would were prepared as two separate parts. The stabilized natural rubber latex (NRL) 100 parts with hydroxy ethyl cellulose (HEC) 2 parts as stabilizer and a delayed - action coacervant (sodium meta silicate as a delaying agent) 5 parts on one hand and the dry blend of cement 65 parts soluble in 65 parts of water as a paste on the other hand were mixed thoroughly on site. (HEC) was added to the rubber latex to prevent the coagulation of the rubber latex with the electrolyte (sodium meta silicate) present in the rubber mixture. Two kinds of stabilization occurred in the rubber part, namely steric stabilization and the stabilization against electrolyte. The effect of delayed - action coacervant (sodium meta silicate) on the initial setting time of rubber - cement mould showed that the molding process did not occur at sodium meta silicate concentration less than 2.66 parts per 100 parts of rubber latex (phr), and the optimum concentration used was 5% parts of rubber latex. It was observed that addition of a delaying agent (Sodium meta silicate) to the rubber part enhanced the delaying mechanism in the time needed for the molding process, while the addition of the delaying agent to the cement part did not have any effect on retardation of the molding process. Chemical coacervants function mainly by reducing the {zeta} potential which is associated with the electrical double layer surrounding the latex particle. This reduction may brought about in at least three distinct ways which take place in the system studied. 5 figs., 3 tabs.

  16. Labbtex: Toolbox para generación de informes en LATEX para Matlab

    Directory of Open Access Journals (Sweden)

    José Luis Almazán Gárate

    2012-10-01

    Full Text Available En este artículo se presenta el software desarrollado por el Equipo H3lite dentro del Departamento de Ingeneniería Civil. Transportes de la Escuela de Ingenieros de Caminos, Canales y Puertos de la Universidad Politécnica de Madrid para la generación de informes enLATEX mediante el software Matlab® y la integración en sus rutinas, Labbtex.La librería Labbtex proporciona un marco flexible para mezclar texto y código Matlab® para la generación automática de documentos. Un rchivo fuente simple contiene el texto de documentación y el código Matlab, al correr la aplicación se genera un documento final LATEX que contiene el texto, gráficos y tablas indicados con el formato de un documento LATEX. El código Matlab genera un documento LATEX usando la sintaxis. Así, LATEX (para composición de texto de alta calidad y Matlab® (para cálculo matemático pueden usarse simultáneamente. Esto permite la generación de informes en tiempo real con un uso de recursos mínimo.

  17. 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.

  18. The Effectiveness of Using STAR Math to Improve PSSA Math Scores

    Science.gov (United States)

    Holub, Sherry L.

    2017-01-01

    This is a quantitative study examining whether STAR Math, a student monitoring system, can improve PSSA Math scores. The experimental school used STAR Math during the 2015-2016 school year in grouping students for remediation and intervention. The control school used traditional curriculum measures to group students for remediation and…

  19. Advanced Math Course Taking: Effects on Math Achievement and College Enrollment

    Science.gov (United States)

    Byun, Soo-yong; Irvin, Matthew J.; Bell, Bethany A.

    2015-01-01

    Using data from the Educational Longitudinal Study of 2002-2006, the authors investigated the effects of advanced math course taking on math achievement and college enrollment and how such effects varied by socioeconomic status and race/ethnicity. Results from propensity score matching and sensitivity analyses showed that advanced math course…

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

    International Nuclear Information System (INIS)

    Rottstegge, J.; Arnold, M.; Herschke, L.; Glasser, G.; Wilhelm, M.; Spiess, H.W.; Hergeth, W.D.

    2005-01-01

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

  1. 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...... properties of NRL and synthetic gloves and the role of glove powder. The review shows that NRL medical gloves, when compared with synthetic gloves, tend to be stronger, more flexible and better accepted by clinicians. The introduction of powder-free gloves has been associated with reductions in protein...

  2. 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.

  3. Affective and Motivational Factors Mediate the Relation between Math Skills and Use of Math in Everyday Life

    Science.gov (United States)

    Jansen, Brenda R. J.; Schmitz, Eva A.; van der Maas, Han L. J.

    2016-01-01

    This study focused on the use of math in everyday life (the propensity to recognize and solve quantitative issues in real life situations). Data from a Dutch nation-wide research on math among adults (N = 521) were used to investigate the question whether math anxiety and perceived math competence mediated the relationship between math skills and use of math in everyday life, taken gender differences into account. Results showed that women reported higher math anxiety, lower perceived math competence, and lower use of math in everyday life, compared to men. Women's skills were estimated at a lower level than men's. For both women and men, higher skills were associated with higher perceived math competence, which in turn was associated with more use of math in everyday life. Only for women, math anxiety also mediated the relation between math skills and use of math in everyday life. PMID:27148122

  4. Affective and motivational factors mediate the relation between math skills and use of math in everyday life

    Directory of Open Access Journals (Sweden)

    Brenda RJ Jansen

    2016-04-01

    Full Text Available This study focused on the use of math in everyday life (the propensity to recognize and solve quantitative issues in real life situations. Data from a Dutch nation-wide research on math among adults (N = 521 were used to investigate the question whether math anxiety and perceived math competence mediated the relationship between math skills and use of math in everyday life, taken gender differences into account. Results showed that women reported higher math anxiety, lower perceived math competence, and lower use of math in everyday life, compared to men. Women's skills were estimated at a lower level than men's. For both women and men, higher skills were associated with higher perceived math competence, which in turn was associated with more use of math in everyday life. Only for women, math anxiety also mediated the relation between math skills and use of math in everyday life.

  5. Math and Gender: Is Math a Route to a High-Powered Career?

    DEFF Research Database (Denmark)

    Joensen, Juanna Schrøter; Nielsen, Helena Skyt

    There is a large gender gap in advanced math coursework in high school that many believe exists because girls are discouraged from taking math courses. In this paper, we exploit an institutional change that reduced the costs of acquiring advanced high school math to determine if access is, in fact......, the mechanism - in particular for girls at the top of the math ability distribution. By estimating marginal treatment effects of acquiring advanced math qualifications, we document substantial beneficial wage effects from encouraging even more females to opt for these qualifications. Our analysis suggests...... that the beneficial effect comes from accelerating graduation and attracting females to high-paid or traditionally male-dominated career tracks and to CEO positions. Our results may be reconciled with experimental and empirical evidence suggesting there is a pool of unexploited math talent among high ability girls...

  6. 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.; Van Mele, B.; 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

  7. Proceedings of the international symposium on radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    Machi, Sueo

    1990-01-01

    The First International Symposium on Radiation Vulcanization of Natural Rubber Latex (RVNRL) was held from 26 to 28 July 1989 at Tokyo and Takasaki. In these proceedings, thirty six papers presented at the Symposium are compiled. Main topics are commercial application of RVNRL, characterization of NR latex and vulcanization, properties of radiation vulcanized NR latex, development of sensitizers, mechanism of RVNRL, RVNRL with electron beams, and new Co-60 irradiator for RVNRL. Absence of nitrosamines and low cytotoxicity of radiation vulcanized NR latex are recognized as the remarkable advantages of RVNRL. The radiation vulcanization process for the production of protective rubber gloves for radioactive contamination was presented as the first commercial success in RVNRL. It was reported that various kinds of rubber articles for medical uses have being developed in West Germany. A sensitizer system consisting of n-butyl acrylate and t-butyl hydroperoxide was found to reduce the vulcanization dose to 8 kGy. (author)

  8. 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%.

  9. Pilot scale experiments on radiation vulcanization of NR latex

    Science.gov (United States)

    Ridwan, M.

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

  10. Principals in Partnership with Math Coaches

    Science.gov (United States)

    Grant, Catherine Miles; Davenport, Linda Ruiz

    2009-01-01

    One of the most promising developments in math education is the fact that many districts are hiring math coaches--also called math resource teachers, math facilitators, math lead teachers, or math specialists--to assist elementary-level teachers with math instruction. What must not be lost, however, is that principals play an essential role in…

  11. Counseling the Math Anxious

    Science.gov (United States)

    Tobias, Sheila; Donady, Bonnie

    1977-01-01

    Describes the rationale and mode of operations for a Math Clinic at Wellesley University and Wesleyan College where counselors and math specialists work together to combat "math anxiety," particularly in female students. (HMV)

  12. Detection and toxicity assessment of nitrosamines migration from latex gloves in the Chinese market.

    Science.gov (United States)

    Feng, Di; Wang, Huiping; Cheng, Xuelian; Wang, Jiedong; Ning, Lifeng; Zhou, Qingfeng; Zhou, Yue; Yang, Quanli

    2009-09-01

    Nitrosamines are potent carcinogens and have been found in latex products. In 2007, twenty-seven natural latex gloves including sterile gloves, examination gloves and household use gloves were sampled from the Chinese market. This study monitored the migration of nitrosamines and nitrosatable substance from these gloves, and evaluated their mutagenicity using a Salmonella typhimurium mutation assay (Ames assay) with the strains TA98, TA97, TA100 and TA102 and by a micronucleus test (MN test) using ICR mice. In addition, the cytotoxicity of these compounds was determined by a MTT assay. N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA) and N-nitrosodibutylamine (NDBA) were all found in samples treated with artificial sweat for 4h at 37 degrees C, and total nitrosamines varied from 18.89 to 244.51microg/Kg. The nitrosamine mixture of NDMA, NDEA and NDBA was used in both the Ames assay and the MN test. The proportion of NDMA, NDEA and NDBA (1:10:20) was selected according to the proportion of nitrosamines migration from sample E05. In the Ames assay, the lowest dose (1.98 x 10(-3)microg per plate) produced a positive result in the TA98 strain, corresponding to nitrosamines migration from sample E05 of 0.016g (the total nitrosamines migration from glove E05 was 122.55 microg/kg). The TA100 strain responded positively at a dose of 4.96 x 10(-2)microg per plate, corresponding to nitrosamines migration from glove E05 of 0.040g. The MN test showed nitrosamine migration of 3.04 mg from 2066 pairs of sample E05 and could induce micronuclei in one mouse weighing 28g (average weight of one E05 glove was 6g). Extracts from gloves were found to be cytotoxic and there was a significant correlation between cytotoxicity (IC50) and the release level of nitrosamines. In conclusion, in view of the high content of nitrosamines in latex gloves and the potential toxicity of nitrosamines migration from these gloves, it is suggested that both an effective and feasible detection

  13. Latex imaging by environmental STEM: application to the study of the surfactant outcome in hybrid alkyd/acrylate systems.

    Science.gov (United States)

    Faucheu, Jenny; Chazeau, Laurent; Gauthier, Catherine; Cavaillé, Jean-Yves; Goikoetxea, Monika; Minari, Roque; Asua, José M

    2009-09-01

    Among other uses, latexes are a successful alternative to solvent-borne binders for coatings. Efforts are made to produce hybrid nanostructured latexes containing an acrylic phase and an alkyd phase. However, after the film-forming process, the surfactant used to stabilize these latexes remains in the film, and its location can have a drastic effect on the application properties. Among the processing parameters, the alkyd hydrophobicity can strongly influence this location. This article aims at the imaging of these surfactant molecules in two hybrid latexes with different hydrophobicity level of the alkyd resin. A first part of this paper is dedicated to the understanding of the contrast provided by the surfactant in environmental STEM imaging of latexes. Then, the influence of surfactant-polymer affinity on the surfactant location after film-forming of those hybrid alkyd/acrylate latexes is studied by this technique. It is shown that in the hybrid latex with an alkyd shell (obtained with the most hydrophilic resin), the surfactant molecules tend to remain buried in the alkyd phase. Conversely, in the hybrid latex with an acrylate shell (in the case of the most hydrophobic resin), the surfactant molecules tend to gather into islands like in pure acrylate latex films.

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

    International Nuclear Information System (INIS)

    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

  15. Radiation vulcanization of natural rubber latex with low energy accelerator-II

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Md. Emdadul; Makuuchi, Keizo; Ikeda, Kenichi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Mitomo, Hiroshi [Gunma Univ., Faculty of Engineering, Dept. of Biological and Chemical Engineering, Kiryu, Gunma (Japan)

    2002-03-01

    The natural rubber latex (NRL) was radiation vulcanized under a low energy electron accelerator. Accelerating voltage and maximum beam current of this accelerator are 250 kV and 10 mA respectively. Irradiation was carried out in a reaction vessel with constant stirring. The capacity of the vessel is 18 liters. Radiation vulcanization accelerators (RVA) were normal butyl acrylate (n-BA) and nonane-diol-diacrylate (NDDA). NDDA has no bad smell like that of n-BA. 20 minutes irradiation time is enough to vulcanize 14 liters of latex when 5 phr RVA (both types) are used. Maximum of {approx}30 MPa tensile strength was obtained with 5 phr NDD-A. However the remained NDDA is difficult to remove due to high molecular weight. Water-extractable proteins content was determined in dipped films for various leaching conditions without and with additive (polyvinyl alcohol, PVA). Water extractable proteins content is reduced to {<=} 41 by adding 5 phr PVA and leaching for 8 hours. The tackiness of the dipped films is reduced to 0.1 from 9 gf by mixing 6 phr PVA with the irradiated latex. Hand gloves (surgical and examination) were successfully produced from the irradiated latex. (author)

  16. GRE math tests

    CERN Document Server

    Kolby, Jeff

    2014-01-01

    Twenty-three GRE Math Tests! The GRE math section is not easy. There is no quick fix that will allow you to ""beat"" the section. But GRE math is very learnable. If you study hard and master the techniques in this book, your math score will improve--significantly! The GRE cannot be ""beaten."" But it can be mastered--through hard work, analytical thought, and by training yourself to think like a test writer. Many of the problems in this book are designed to prompt you to think like a test writer. For example, you will find ""Duals."" These are pairs of similar problems in which only one prop

  17. On the Leaky Math Pipeline: Comparing Implicit Math-Gender Stereotypes and Math Withdrawal in Female and Male Children and Adolescents

    Science.gov (United States)

    Steffens, Melanie C.; Jelenec, Petra; Noack, Peter

    2010-01-01

    Many models assume that habitual human behavior is guided by spontaneous, automatic, or implicit processes rather than by deliberate, rule-based, or explicit processes. Thus, math-ability self-concepts and math performance could be related to implicit math-gender stereotypes in addition to explicit stereotypes. Two studies assessed at what age…

  18. Thermodynamics of swelling of latex particles with two monomers: a sensitivity analysis

    NARCIS (Netherlands)

    Maxwell, I.A.; Noel, E.F.J.; Schoonbrood, H.A.S.; German, A.L.

    1993-01-01

    A sensitivity anal. is performed to det. at what conditions the simplified model for swelling of latex particles by two monomers or two solvents is valid. This model proposes that, inter alia, the fractions of two monomers in the latex particles and in the monomer droplets are equal. The model is a

  19. Analysis of sulfidic linkages formed in natural rubber latex medical gloves by using X-ray absorption near edge structure

    Science.gov (United States)

    Chankrachang, M.; Limphirat, W.; Yongyingsakthavorn, P.; Nontakaew, U.; Tohsan, A.

    2017-09-01

    A study of sulfidic linkages formed in natural rubber (NR) latex medical gloves by using X-ray Absorption Near Edge Structure (XANES) is presented in this paper. The NR latex compound was prepared by using prevulcanization method, that is, it was prevulcanized at room temperature for 24 hrs before utilization. After the 24 hrs of prevulcanization, the latex film samples were obtained by dipping process. The dipped films were subjected to vulcanize at 110°C for 5 to 25 min. It was observed that after the compound was prevulcanized for 24 hrs, polysulfidic linkages were mainly formed in the sample. It was however found that after curing at 110°C for 5-25 min, the polysulfidic linkages are tended to change into disulfide linkages. Especially, in the case of 25 minutes cured sample, disulfide linkages are found to be the main linkages. In term of tensile strength, it was observed that when cure time increased from 5 - 10 min, tensile strengths were also increased. But when the cure time of the film is 25 minutes, tensile strength was slightly dropped. The dropped of tensile strength when cure time is longer than 10 minutes can be ascribed to a degradation of polysulfidic and disulfidic linkages during curing. Therefore, by using XANES analysis, it was found to be very useful to understand the cure characteristic, thus it can be very helpful to optimize cure time and tensile properties of the product.

  20. Reciprocal Relations among Motivational Frameworks, Math Anxiety, and Math Achievement in Early Elementary School

    Science.gov (United States)

    Gunderson, Elizabeth A.; Park, Daeun; Maloney, Erin A.; Beilock, Sian L.; Levine, Susan C.

    2018-01-01

    School-entry math achievement is a strong predictor of math achievement through high school. We asked whether reciprocal relations among math achievement, math anxiety, and entity motivational frameworks (believing that ability is fixed and a focus on performance) can help explain these persistent individual differences. We assessed 1st and 2nd…

  1. The relation between math self-concept, test and math anxiety, achievement motivation and math achievement in 12 to 14-year-old typically developing adolescents

    NARCIS (Netherlands)

    Timmerman, H.L.; Toll, S.W.M.; van Luit, J.E.H.

    2017-01-01

    :This study examines the relation between math self-concept, test and math anxiety, achievement motivation, and math achievement in typically developing 12 to 14-year-old adolescents (N = 108) from a school for secondary education in the Netherlands. Data was obtained using a math speed test,

  2. Using an Intelligent Tutor and Math Fluency Training to Improve Math Performance

    Science.gov (United States)

    Arroyo, Ivon; Royer, James M.; Woolf, Beverly P.

    2011-01-01

    This article integrates research in intelligent tutors with psychology studies of memory and math fluency (the speed to retrieve or calculate answers to basic math operations). It describes the impact of computer software designed to improve either strategic behavior or math fluency. Both competencies are key to improved performance and both…

  3. Advanced Math: Closing the Equity Gap. Math Works

    Science.gov (United States)

    Achieve, Inc., 2013

    2013-01-01

    Minority and low-income students are less likely to have access to, enroll in and succeed in higher-level math courses in high school than their more advantaged peers. Under these circumstances, higher-level math courses function not as the intellectual and practical boost they should be, but as a filter that screens students out of the pathway to…

  4. Antioxidant and sensitizer effect on the stability of natural rubber latex vulcanized by gamma rays

    International Nuclear Information System (INIS)

    Canavel, V.

    1993-01-01

    The natural rubber latex was vulcanized by gamma rays and electrons beam, in the presence and absence of sensitizer at room temperature. The sensitizers were the following; n-butyl acrylate (n-BA) / t-butyl hydroperoxide (t-B H) / KOH, C Cl 4 / potassium laurate and n-BA / KOH. The studied antioxidants, Irganox 1520, Vulcanox SP and Vulcanox BKF, were added to the latex after irradiation. Among the studied antioxidants in function of tensile strength (TS) after the aging of rubber plates, the Irganox was the best efficient on the gamma vulcanization in the presence of n-BA/t-B H/KOH, because only 0,20 p hr is enough to obtain the greatest increase of TS, that was 34%, 12 MPa to 16 MPa. The formulating method of latex with the sensitizer constituted the 3,0 p hr of n-BA/ 0,1 p hr of t-B H and 0,2 p hr of KOH, was evaluated respecting the TS of rubber plates. The electrons beam vulcanization produces the greatest reversible perturbance in the colloidal stability of latex after irradiation caused by radiolytic species absorption that promotes the increase of particle size. The antioxidant also contributes to reversible destabilization of gamma irradiated latex, because it is also adsorbed by particles surface. The relation between the latex viscosity and the TS of respective rubber plates is reverse, showing the latex stability affects the quality of rubber goods. (author)

  5. The entry of free radicals into polystyrene latex particles

    International Nuclear Information System (INIS)

    Adams, M.E.; Trau, M.; Gilbert, R.C.; Napper, D.R.

    1988-01-01

    Mechanistic understanding of the processes governing the kinetics of emulsion polymerization has both scientific and technical interest. One component of this process that is poorly understood at present is that of free radical entry into latex particles. Measurements were made of the entry rate coefficient as a function of temperature for free radicals entering polystyrene latex particles in seeded emulsion polymerizations initiated by γ-rays. The activation energy for entry was found to be less than 24 ± 3 kJ mol -1 , consistent with entry being controlled by a physical (e.g. diffusional) rather than a chemical process. Measurement of the entry rate coefficient as a function of the γ-ray dose rate suggested that the factors that determine the entry rate when the primary free radicals are uncharged are similar to those that determine the entry rate for charged free radicals derived from chemical initiation by peroxydisulfate. This result was consistent with measurements of the entry rate coefficient of charged free radicals derived from peroxydisulfate; these data were found to be virtually independent of both the extent of the latex surface coverage by the anionic surfactant sodium dodecyl sulfate and the ionic strength of the continuous phase. The data refute several proposals given in the literature for the rate-determining step for entry, being inconsistent with control by collision of free radicals with the latex particles, surfactant desorption, and an electrostatic barrier arising from the colloidal nature of the entering free radical. The origin of the activation energy for entry remains obscure

  6. Osmotic de-swelling and swelling of latex dispersions

    International Nuclear Information System (INIS)

    Bonnet-Gonnet, Cecile

    1993-01-01

    This research thesis reports the comparison of, on the one hand, direct measurements of de-swelling resistance of latex dispersions obtained by osmotic pressure with, on the other hand, predictions made by models of electrostatic interactions. This resistance is explained in the case of sulphate-stabilised polystyrene particles (direct repulsion between charged particles), and in the case of copolymer (ps-pba) particles covered by an amphiphilic polymer (interactions between surface macromolecules and polymers). The study of de-swelling and swelling cycles highlights the existence of thresholds beyond which the concentrated dispersion has some cohesion. This irreversibility can be modelled by a Van der Waals attraction. The role of hydrophobic forces in latex destabilisation is studied [fr

  7. Anticancer activity of flavonol and flavan-3-ol rich extracts from Croton celtidifolius latex.

    Science.gov (United States)

    Biscaro, Fernanda; Parisotto, Eduardo Benedetti; Zanette, Vanilde Citadini; Günther, Tania Mara Fischer; Ferreira, Eduardo Antonio; Gris, Eliana Fortes; Correia, João Francisco Gomes; Pich, Claus Tröger; Mattivi, Fulvio; Filho, Danilo Wilhelm; Pedrosa, Rozangela Curi

    2013-06-01

    Croton celtidifolius Baill (Euphorbiaceae) is a tree found in the Atlantic Forest in Southern Brazil, where it is commonly known as "Sangue-de-Dragão". Its red latex is used traditionally for treating ulcers, diabetes and cancer. To evaluate antitumor activities of Croton celtififolius latex in vitro and in vivo. Phytochemical analyses were conducted using HPLC-DAD-MS. Cytotoxic, nuclease and pro-apoptotic properties were determined using the tetrazolium salt assay (MTT), plasmid DNA damage assay and ethidium bromide (EB)/acridine orange methods, respectively, and antitumor activity was determined in the Ehrlich ascites carcinoma (EAC) mouse model. Phytochemical studies indicated a high phenol content of flavonols (45.67 ± 0.24 and 18.01 ± 0.23 mg/mL of myricetin and quercetin, respectively) and flavan-3-ols (114.12 ± 1.84 and 1527.41 ± 16.42 mg/L of epicatechin and epigallocatechin, respectively) in latex. These compounds reduced MCF-7 and EAC cell viability in the MTT assay (IC50 = 169.0 ± 1.8 and 187.0 ± 2.2 μg/mL, respectively). Latex compounds caused significant DNA fragmentation and increased the number of apoptotic cells (negative control (NC), 12%; latex, 41%) as indicated by differential staining in the EB/acridine orange assay. The in vivo latex treatment at 3.12 mg/kg/day reduced the body weight by 7.57 ± 2.04 g and increased median survival time to 17.5 days when compared to the NC group (13.0 days). In addition, the highest latex concentration inhibited tumor growth by 56%. These results agree with ethno-pharmacological reports showing cytotoxicity and antitumor activity of C. celtidifolius latex. The mechanism of antitumor action may be related to direct DNA fragmentation that reduces survival and induces apoptosis.

  8. Math Safari.

    Science.gov (United States)

    Nelson, Vaunda; Stanko, Anne

    1992-01-01

    Describes Math Safari, a mathematical, scientific, geographic, informational adventure for fourth grade students. It integrates all curriculum areas and other skills by using information children must find in books to pose math problems about animals. It encourages cooperative learning, critical reading, analysis, and use of research skills. (SM)

  9. The effect of emulsifier on the stability of irradiated LA-TZ latex

    International Nuclear Information System (INIS)

    Made Sumarti K; Utama, Marga; Puspitasari, Tita

    1998-01-01

    The effect of six kinds of stabilizer on the stability of the concentrated LA-TZ latex which contains n-BA have been studied. The six stabilizers are: 1. Naphthalene sulfonic acid formaldehyde condensate, 2. Sodium dialkyl sulfosuccinate, 3. Triethanol amine lauryl sulfate, 4. Sodium polyoxyethylene alkyl phenol ether sulfate, 5. Dodecyl benzene sulfonic acid (Neopelex FS), and 6. Ammonium laurat. The concentrations of the stabilizers are in the range of 0,1 to 0,3% and of the n-BA is 5phr (per hundred rubber). The field natural rubber latex was stabilized by Tetramethyl tiuram disulfide - Zine oxide (TMTD-ZnO) and ammonium gas, and was concentrated by centrifuge. The obtain concentrated LA-TZ latex was added by the n-BA and was kept with various storage time i.e. o, 2, 4, 6, 18, and 24 hours. It was found that the stable latex was irradiated by 15 kGy dose and the physical properties was tested, then the maximum tensile strength of 223,3 kg/cm 2 was found on Neopelex FS concentrate at 0,1%. (authors)

  10. Attentional Bias in Math Anxiety

    Directory of Open Access Journals (Sweden)

    Orly eRubinsten

    2015-10-01

    Full Text Available Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety as well (i.e., a persistent negative reaction to math. Twenty seven participants (14 with high levels of math anxiety and 13 with low levels of math anxiety were presented with a novel computerized numerical version of the well established dot probe task. One of 6 types of prime stimuli, either math related or typically neutral, were presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks. Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in math anxiety. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words. These findings suggest that attentional bias is linked to unduly intense math anxiety symptoms.

  11. Math Performance as a Function of Math Anxiety and Arousal Performance Theory

    Science.gov (United States)

    Farnsworth, Donald M., Jr.

    2009-01-01

    While research continues to link increased math anxiety with reduced working memory, the exact nature of the relationship remains elusive. In addition, research regarding the extent of the impact math anxiety has on working memory is contradictory. This research clarifies the directional nature of math anxiety as it pertains to working memory, and…

  12. 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....

  13. 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.

  14. 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.

  15. Implicit Social Cognitions Predict Sex Differences in Math Engagement and Achievement

    Science.gov (United States)

    Nosek, Brian A.; Smyth, Frederick L.

    2011-01-01

    Gender stereotypes about math and science do not need to be endorsed, or even available to conscious introspection, to contribute to the sex gap in engagement and achievement in science, technology, engineering, and mathematics (STEM). The authors examined implicit math attitudes and stereotypes among a heterogeneous sample of 5,139 participants.…

  16. Math Stuff

    CERN Document Server

    Pappas, Theoni

    2002-01-01

    Whether it's stuff in your kitchen or garden, stuff that powers your car or your body, stuff that helps you work, communicate or play, or stuff that you've never heard of you can bet that mathematics is there. MATH STUFF brings it all in the open in the Pappas style. Not many people think of mathematics as fascinating, exciting and invaluable. Yet Pappas writes about math ideas in such a way that conveys its often overlooked fascination, excitement, and worth. MATH STUFF deals with 38 topics in an non-threatening way that piques our curiosities. Open the book at random, and learn about such to

  17. Diagnostic value of latex agglutination test in diagnosis of acute bacterial meningitis

    Directory of Open Access Journals (Sweden)

    Syeda Fasiha Mohammadi

    2013-01-01

    Full Text Available Objectives: To know the incidence of bacterial meningitis in children below five years of age. To compare conventional culture and antigen detection methods ( Latex agglutination test. Materials and Methods: 100 CSF samples of clinically suspected meningitis cases in children below 5 years of age were included. The samples were subjected to cell count, Gram stain, culture and LAT. The organisms isolated in the study were characterized according to standard procedures. Results: Of the 100 cases studied, 31 cases were diagnosed as ABM by Gram stain, culture and latex agglutination test as per WHO criteria. The hospital frequency of ABM was 1.7%. 15 (48.38 cases were culture positive. Gram stain was positive in 22(70.96 cases and LAT in 17(54.83 cases. Haemophilus influenzae was the most common causative agent of acute bacterial meningitis followed by S.pneumoniae. Case fatality rate was 45.16%.The sensitivity and specificity of LAT was 66.66% and 87.91% respectively. Conclusion : Bacterial meningitis is a medical emergency and early diagnosis and treatment is life saving and reduces chronic morbidity. LAT was more sensitive compared to conventional Gram stain and Culture technique in identifying the fastidious organisms like H.influenzae, S.pneumoniae and Group B Streptococcus. However, the combination of Gram stain, Culture and LAT proved to be more productive than any of the single tests alone.

  18. 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.

  19. Latex-mediated synthesis of ZnS nanoparticles: green synthesis approach

    Science.gov (United States)

    Hudlikar, Manish; Joglekar, Shreeram; Dhaygude, Mayur; Kodam, Kisan

    2012-05-01

    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-2) ions that are donated to Zn ions under present experimental conditions. Source of sulphide (S-2) ions is still unclear, but we speculate that cysteine or thiol residues present in enzyme curcain may be donating these sulphide (S-2) ions.

  20. Latex-mediated synthesis of ZnS nanoparticles: green synthesis approach

    International Nuclear Information System (INIS)

    Hudlikar, Manish; Joglekar, Shreeram; Dhaygude, Mayur; Kodam, Kisan

    2012-01-01

    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 −2 ) ions that are donated to Zn ions under present experimental conditions. Source of sulphide (S −2 ) ions is still unclear, but we speculate that cysteine or thiol residues present in enzyme curcain may be donating these sulphide (S −2 ) ions.

  1. The Effects of the Elevate Math Summer Program on Math Achievement and Algebra Readiness. REL 2015-096

    Science.gov (United States)

    Snipes, Jason; Huang, Chun-Wei; Jaquet, Karina; Finkelstein, Neal

    2015-01-01

    The Effects of the Elevate Math summer program on math achievement and algebra readiness: This randomized trial examined the effects of the Elevate Math summer program on math achievement and algebra readiness, as well as math interest and self-efficacy, among rising 8th grade students in California's Silicon Valley. The Elevate Math summer math…

  2. Latex glove sensitivity amongst diagnostic imaging healthcare ...

    African Journals Online (AJOL)

    kemrilib

    Sciences, Faculty of Health Sciences and Technology, University of Nigeria, Enugu Campus, Enugu. State, Nigeria. .... Occupation. No of .... latex protein residue and act as a hapten or .... at Work Act, 1989 and the safety, Health and Welfare at.

  3. Incidence of latex harvesting technologies on agronomic and ...

    African Journals Online (AJOL)

    Incidence of latex harvesting technologies on agronomic and physiological parameters and profitability of some rapid metabolic class clones of rubber tree ( Hevea brasiliensis ) in southwestern Côte d'Ivoire.

  4. 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

  5. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    International Nuclear Information System (INIS)

    Keong, C C; Zin, W M Wan; Ibrahim, P; Ibrahim, S

    2010-01-01

    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

  6. The effect of proteins on the aging properties of radiation vulcanized natural rubber latex

    International Nuclear Information System (INIS)

    Abad, L.V.

    1993-01-01

    The effect of natural rubber latex (NRL) proteins on the aging properties of NRL films was investigated. SDS-PAGE electrophoresis of the rubber proteins in NRL (Sri-Lanka) indicated a total of 18 proteins. A sharp decrease in tensile strength was observed after aging when NRL films were leached in 1% NH 4 OH. However, when these films were soaked in ethanol prior to leaching, the aging properties approximated those of the unleashed samples. Electrophoretic analysis of the proteins present in the NH 3 extracts of leached RVNRL films showed a high concentration of the protein herein. This protein was not found in the NH 3 extracts of ethanol soaked films. NRL proteins were shown to decelerate the aging process of Radiation Vulcanized Natural Rubber Latex (RVNRL) films. Among the proteins, herein exhibited good anti-aging properties. The hydrolyzates from NR proteins also enhanced considerably the aging properties of RVNRL. (auth.). 8 refs.; 40 figs.; 30 tabs

  7. The Effects of Math Anxiety

    Science.gov (United States)

    Andrews, Amanda; Brown, Jennifer

    2015-01-01

    Math anxiety is a reoccurring problem for many students, and the effects of this anxiety on college students are increasing. The purpose of this study was to examine the association between pre-enrollment math anxiety, standardized test scores, math placement scores, and academic success during freshman math coursework (i.e., pre-algebra, college…

  8. Soybean oil in water-borne coatings and latex film formation study by AC impedance

    Science.gov (United States)

    Jiratumnukul, Nantana

    Conventional coalescing agents such as butyl cellosolve, butyl carbitol, and TexanolRTM are widely use in the latex coatings industry to facilitate film formation at ambient temperature. Coalescent aids are composed of solvents with low evaporation rates. After water evaporates, coalescent aids would help soften polymer molecules and form continuous films, then gradually evaporates from the film. Coalescent aids, therefore, are considered as volatile organic compounds (VOC), which are of environmental concern. The main purpose of this research project was to prepare a fatty acid glycol ester from soybean oil and glycol (polyols). The soybean oil glycol ester can be used as a coalescent aid in latex paint formulation. The soybean oil glycol ester not only lowered the minimum film formation temperature of latex polymers and continuous film formed at ambient temperature, but also after it has facilitated film formation, does not substantially evaporate, but becomes part of the film. Soybean oil glycol esters, therefore, can reduce the VOC levels and facilitate film formation of latex paints. In the second part of this research AC-Impedance was used to investigate the efficiency of soybean oil coalescent aid in latex film formation relative to the conventional ones. The coating resistance showed that the efficiency of film formation was increased as a function of dry time. The coating resistance also exhibited the effect of soybean oil ester in latex film formation in the same fashion as a conventional coalescent aid, TexanolRTM.

  9. Math

    CERN Document Server

    Robertson, William C

    2006-01-01

    Flummoxed by formulas? Queasy about equations? Perturbed by pi? Now you can stop cursing over calculus and start cackling over Math, the newest volume in Bill Robertson's accurate but amusing Stop Faking It! best sellers. As Robertson sees it, too many people view mathematics as a set of rules to be followed, procedures to memorize, and theorems to apply. This book focuses on the reasoning behind the rules, from math basics all the way up to a brief introduction to calculus.

  10. Test trial radiation vulcanization of natural rubber latex in Jakarta Indonesia

    International Nuclear Information System (INIS)

    Devendra, R.; Kulatunge, S.S.; Chandralal, H.N.K.K.; Kalyani, N.M.V.; Seneviratne, J.; Wellage, S.

    1994-01-01

    Radiation vulcanization of natural rubber latex (RVNRL) can be used to make large quantities of specially stabilized latex. It is possible to obtain RVNRL films of tensile strength over 25 MPa. The films could be either coagulant dipped or cast. It is very important to determine the correct radiation dose which gives the maximum tensile strength. Cross linking density or prevulcanized relax modulus (PRM) at 100% is a reliable property to control the prevulcanization

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  12. Understand electrical and electronics maths

    CERN Document Server

    Bishop, Owen

    1993-01-01

    Understand Electrical and Electronics Maths covers elementary maths and the aspects of electronics. The book discusses basic maths including quotients, algebraic fractions, logarithms, types of equations and balancing of equations. The text also describes the main features and functions of graphs and the solutions to simpler types of electronics problems. The book then tackles the applications of polar coordinates in electronics, limits, differentiation and integration, and the applications of maths of rates of change in electronics. The activities of an electronic circuit; techniques of math

  13. Use of micrometric latex beads to improve the porosity of hydroxyapatite obtained by chemical coprecipitation method

    Science.gov (United States)

    Webler, G. D.; Rodrigues, W. C.; Silva, A. E. S.; Silva, A. O. S.; Fonseca, E. J. S.; Degenhardt, M. F. S.; Oliveira, C. L. P.; Otubo, L.; Barros Filho, D. A.

    2018-04-01

    Hydroxyapatite is one of the most important biomaterials whose application mainly extends to implants and drug delivery. This work will discuss the changes in the pore size distribution of hydroxyapatite when there are latex beads present during the synthesis. These changes were monitored using different techniques: small angle X-ray scattering, X-ray diffraction, thermal gravimetrical analysis, N2 adsorption, scanning and transmission electron microscopy. Latex beads and hydroxyapatite form a single nanocomposite with well-distinguished inorganic and organic phases. Latex bead removal in the temperature range of 300-600 °C did not modify the original crystalline structure of hydroxyapatite. However, the latex beads favored an increase in the adsorption capacity of mesopores at temperatures higher than their glassy transition (Tg). The main result of this research work consists on the increase of surface area and pore size distribution obtained after the removal of latex beads template. Latex beads have been used in a different approach changing the porosity of hydroxyapatite scaffolds not only introducing new routes for cell integration but also broadening the pore size distribution which can result in a more high efficiency for drug release in living cells.

  14. The Development and Validation of the Children's Anxiety in Math Scale

    Science.gov (United States)

    Jameson, Molly M.

    2013-01-01

    Math anxiety has been historically overlooked in samples of children. This may be due in part to the lack of appropriate tools to measure anxiety in young children. The current exploratory study reports on the development and examination of reliability, validity, and factor structure of a new tool to measure math anxiety in young children. The…

  15. The role of proteins on the thermal oxidative aging of radiation vulcanized natural rubber latex

    International Nuclear Information System (INIS)

    Abad, L.V.; Rosa, A. de la; Keizo Makuuchi; Fumio Yoshii

    1996-01-01

    The effect of Hevea latex proteins on the aging properties of radiation vulcanized natural rubber latex (RVNRL) was investigated. Unpurified RVNRL films exhibited better aging properties than the purified RVNRL films. A sharp decrease in tensile strength was observed after aging when RVNRL films were leached in 1% NH sub 4 OH. However, when these films were soaked in ethanol prior to leaching, the aging properties approximated those of the unleached samples. Kjeldahl and FT-IR analyses of the leached and unleached RVNRL films indicated a higher protein content for both the unleached and ethanol-soaked films than for leached films. Electrophoretic analysis of the proteins present in the NH, extracts of leached RVNRL films showed a high concentration of hevein. This protein was not found in the ATH, extracts of ethanol soaked films. Hevein was shown to improve the aging properties of RVNRL

  16. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    International Nuclear Information System (INIS)

    Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd; Boondamnoen, O.; Tai, Mun Foong

    2015-01-01

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm −1 and 700 cm −1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (M s ). • High M s of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high potential for the

  17. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd, E-mail: sharifahbee@um.edu.my; Boondamnoen, O.; Tai, Mun Foong

    2015-12-01

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm{sup −1} and 700 cm{sup −1} respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (M{sub s}). • High M{sub s} of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high

  18. Flight Software Math Library

    Science.gov (United States)

    McComas, David

    2013-01-01

    The flight software (FSW) math library is a collection of reusable math components that provides typical math utilities required by spacecraft flight software. These utilities are intended to increase flight software quality reusability and maintainability by providing a set of consistent, well-documented, and tested math utilities. This library only has dependencies on ANSI C, so it is easily ported. Prior to this library, each mission typically created its own math utilities using ideas/code from previous missions. Part of the reason for this is that math libraries can be written with different strategies in areas like error handling, parameters orders, naming conventions, etc. Changing the utilities for each mission introduces risks and costs. The obvious risks and costs are that the utilities must be coded and revalidated. The hidden risks and costs arise in miscommunication between engineers. These utilities must be understood by both the flight software engineers and other subsystem engineers (primarily guidance navigation and control). The FSW math library is part of a larger goal to produce a library of reusable Guidance Navigation and Control (GN&C) FSW components. A GN&C FSW library cannot be created unless a standardized math basis is created. This library solves the standardization problem by defining a common feature set and establishing policies for the library s design. This allows the libraries to be maintained with the same strategy used in its initial development, which supports a library of reusable GN&C FSW components. The FSW math library is written for an embedded software environment in C. This places restrictions on the language features that can be used by the library. Another advantage of the FSW math library is that it can be used in the FSW as well as other environments like the GN&C analyst s simulators. This helps communication between the teams because they can use the same utilities with the same feature set and syntax.

  19. Short-cut math

    CERN Document Server

    Kelly, Gerard W

    1984-01-01

    Clear, concise compendium of about 150 time-saving math short-cuts features faster, easier ways to add, subtract, multiply, and divide. Each problem includes an explanation of the method. No special math ability needed.

  20. Production Of Hollow Toy Product From Radiation Pre vulcanized Natural Rubber Latex (RVNRL) By Using Casting And Moulding Technique

    International Nuclear Information System (INIS)

    Mohd Noorwadi Mat Lazim; Sofian Ibrahim; Muhammad Saiful Omar

    2013-01-01

    Hollow toy products are very synonym to the child from the age of months since it able to stimulating each of their sense such as sight, hearing, taste, touch and smell. Most of hollow toy products are made from natural rubber latex by using moulding and casting technique. The moulding and casting technique is a manufacturing process by pored liquid latex into a mould, which contain cavity of the desired shape. The mould made from plaster of Paris able to absorbs water from latex meanwhile the presence of calcium ions from plaster of Paris will tend to diffuse into latex thus promote formation of deposit on surface of cavity mould. To improve the quality and safety of hollow toy product made from latex, Radiation Pre vulcanized Natural Rubber Latex (RVNRL) has been identified to be used because it can fulfill the standard requirement for latex and also due to its special abilities such as lower modulus (soft latex products), nitrosamines free, low in nitrosatables, free from chemical accelerators induced allergies and better biodegradability. This paper identify the problem appears from the process of making hollow toy products from RVNRL by using moulding and casting technique. (author)

  1. Rubber/clay nanocomposites by combined latex compounding and melt mixing: A masterbatch process

    International Nuclear Information System (INIS)

    Tan, Jinghua; Wang, Xiaoping; Luo, Yuanfang; Jia, Demin

    2012-01-01

    Highlights: → Rubber/Ca-montmorillonite nanocomposites were prepared by the masterbatch process. → Latex compounding method is efficient to improve the Ca-montmorillonite dispersion. → Exfoliated structure was obtained in the masterbatch by latex compounding method. → Intercalated and exfoliated structures were achieved in the vulcanizate. → The properties of vulcanizate are improved by the addition of Ca-montmorillonite. -- Abstract: Rubber/Ca-montmorillonite (Ca-MMT) nanocomposites with well exfoliated Ca-MMT layers were prepared by combination of latex compounding and melt mixing. Firstly, a high Ca-MMT content masterbatch was co-coagulated by natural rubber (NR) latex and modified Ca-MMT aqueous suspension through latex compounding. The masterbatch was added in the system of styrene butadiene rubber (SBR) and epoxidized natural rubber (ENR) by melt mixing subsequently. The X-ray diffraction (XRD) and transmission electronic microscopy (TEM) results showed that intercalated and exfoliated nanocomposites were obtained by the masterbatch technique. The effects of modified Ca-MMT introduction into the rubber matrix, via the masterbatch technique, on the properties of the resulting composites were studied. It was found that the vulcanization was hindered by the incorporation of modified Ca-MMT, while mechanical performances, thermal stability and aging resistance were improved. The increasingly glass transition temperature and the storage modulus with the loading of modified Ca-MMT were measured by dynamic mechanical analysis (DMA).

  2. Solving America's Math Problem

    Science.gov (United States)

    Vigdor, Jacob

    2013-01-01

    Concern about students' math achievement is nothing new, and debates about the mathematical training of the nation's youth date back a century or more. In the early 20th century, American high-school students were starkly divided, with rigorous math courses restricted to a college-bound elite. At midcentury, the "new math" movement sought,…

  3. Teaching Math Their Way.

    Science.gov (United States)

    Tankersley, Karen

    1993-01-01

    Teachers at a K-8 urban school in Phoenix, Arizona, worked to develop an effective math program that generated student interest and positive self-esteem. They eventually set aside classroom and large enclosed porch area to house math manipulative lab, where children could learn new concepts at concrete level. Results are excitement about math and…

  4. Nurses' maths: researching a practical approach.

    Science.gov (United States)

    Wilson, Ann

    To compare a new practical maths test with a written maths test. The tests were undertaken by qualified nurses training for intravenous drug administration, a skill dependent on maths accuracy. The literature showed that the higher education institutes (HEIs) that provide nurse training use traditional maths tests, a practical way of testing maths had not been described. Fifty five nurses undertook two maths tests based on intravenous drug calculations. One was a traditional written test. The second was a new type of test using a simulated clinical environment. All participants were also interviewed one week later to ascertain their thoughts and feelings about the tests. There was a significant improvement in maths test scores for those nurses who took the practical maths test first. It is suggested that this is because it improved their conceptualisation skills and thus helped them to achieve accuracy in their calculations. Written maths tests are not the best way to help and support nurses in acquiring and improving their maths skills and should be replaced by a more practical approach.

  5. Towards anti-corrosion coatings from surfactant-free latexes based on maleic anhydride containing polymers

    NARCIS (Netherlands)

    Soer, W.J.; Ming, W.; Koning, C.E.; Benthem, van R.A.T.M.

    2008-01-01

    We report on the film formation of surfactant-free, artificial latexes based on copolymers containing maleic anhydride. Different metallic substrates, such as aluminum, steel and magnesium alloys, were coated with three different latexes. A commercial polyester based coating was used as a

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

    OpenAIRE

    Amr, Sania; Bollinger, Mary E.

    2004-01-01

    The prevalence of natural rubber latex (NRL) allergy has been estimated to be 5-18% in health care workers, and latex exposure has been one of the leading causes of occupational asthma in the last several years. We present the cases of two nurses who developed sensitivity to NRL, both with dermatologic symptoms and respiratory symptoms that included asthma. They were referred to the University of Maryland for evaluation of their allergies, then for occupational and environmental consults. The...

  7. Radiation graft copolymerization of n-butyl acrylate on natural rubber latex

    International Nuclear Information System (INIS)

    Sundardi, F.; Kadariah, S.

    1986-01-01

    A method of radiation graft copolymerization of n-butyl acrylate (NBA) on natural rubber (NR) latex has been studied. The rate of conversion increases with the increase of NBA in latex. An irradiation dose of about 12 kGy is needed to obtain 90% conversion with 40 phr of NBA in latex. Tensile strength, tear strength, and elongation at break of grafted NR are found to decrease with increasing degree of grafting. The physical strength of a vulcanizate prepared from a mixture of NR and ply-NBA was found to be better than that of NBA-NR graft copolymer vulcanizate. The graft copolymerization reaction takes place in the outer layer of NR particles, and because the secondary bonds between poly-NBA molecules may be weaker than those between NR molecules, the existence of a poly-NBA layer in NR particles will decrease its physical strength

  8. 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.

  9. Math Anxiety and Math Performance in Children: The Mediating Roles of Working Memory and Math Self-Concept

    Science.gov (United States)

    Justicia-Galiano, M. José; Martín-Puga, M. Eva; Linares, Rocío; Pelegrina, Santiago

    2017-01-01

    Background: Numerous studies, most of them involving adolescents and adults, have evidenced a moderate negative relationship between math anxiety and math performance. There are, however, a limited number of studies that have addressed the mechanisms underlying this relation. Aims: This study aimed to investigate the role of two possible…

  10. On the relationship between math anxiety and math achievement in early elementary school: The role of problem solving strategies.

    Science.gov (United States)

    Ramirez, Gerardo; Chang, Hyesang; Maloney, Erin A; Levine, Susan C; Beilock, Sian L

    2016-01-01

    Even at young ages, children self-report experiencing math anxiety, which negatively relates to their math achievement. Leveraging a large dataset of first and second grade students' math achievement scores, math problem solving strategies, and math attitudes, we explored the possibility that children's math anxiety (i.e., a fear or apprehension about math) negatively relates to their use of more advanced problem solving strategies, which in turn relates to their math achievement. Our results confirm our hypothesis and, moreover, demonstrate that the relation between math anxiety and math problem solving strategies is strongest in children with the highest working memory capacity. Ironically, children who have the highest cognitive capacity avoid using advanced problem solving strategies when they are high in math anxiety and, as a result, underperform in math compared with their lower working memory peers. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Evaluation of peptides release using a natural rubber latex biomembrane as a carrier.

    Science.gov (United States)

    Miranda, M C R; Borges, F A; Barros, N R; Santos Filho, N A; Mendonça, R J; Herculano, R D; Cilli, E M

    2018-05-01

    The biomembrane natural (NRL-Natural Rubber Latex), manipulated from the latex obtained from the rubber tree Hevea brasiliensis, has shown great potential for application in biomedicine and biomaterials. Reflecting the biocompatibility and low bounce rate of this material, NRL has been used as a physical barrier to infectious agents and for the controlled release of drugs and extracts. The aim of the present study was to evaluate the incorporation and release of peptides using a latex biomembrane carrier. After incorporation, the release of material from the membrane was observed using spectrophotometry. Analyses using HPLC and mass spectroscopy did not confirm the release of the antimicrobial peptide [W 6 ]Hylin a1 after 24 h. In addition, analysis of the release solution showed new compounds, indicating the degradation of the peptide by enzymes contained in the latex. Additionally, the release of a peptide with a shorter sequence (Ac-WAAAA) was evaluated, and degradation was not observed. These results showed that the use of NRL as solid matrices as delivery systems of peptide are sequence dependent and could to be evaluated for each sequence.

  12. Math-Gender Stereotypes and Career Intentions: An Application of Expectancy-Value Theory

    Science.gov (United States)

    Song, Jingjing; Zuo, Bin; Wen, Fangfang; Yan, Lei

    2017-01-01

    Exposure to negative math-gender stereotypes undermines the intentions of female college students to engage in careers in the math field, yet the mechanisms by which such stereotypes relate to girls' career intentions remain unclear. We simultaneously tested multiple mediators in a sample of 186 female students from one high school in central…

  13. Is math anxiety in the secondary classroom limiting physics mastery? A study of math anxiety and physics performance

    Science.gov (United States)

    Mercer, Gary J.

    This quantitative study examined the relationship between secondary students with math anxiety and physics performance in an inquiry-based constructivist classroom. The Revised Math Anxiety Rating Scale was used to evaluate math anxiety levels. The results were then compared to the performance on a physics standardized final examination. A simple correlation was performed, followed by a multivariate regression analysis to examine effects based on gender and prior math background. The correlation showed statistical significance between math anxiety and physics performance. The regression analysis showed statistical significance for math anxiety, physics performance, and prior math background, but did not show statistical significance for math anxiety, physics performance, and gender.

  14. Frequent IgE sensitization to latex, cow's milk, and egg in children with short bowel syndrome.

    Science.gov (United States)

    Mazon, Angel; Solera, Eva; Alentado, Noemi; Oliver, Fernando; Pamies, Rafael; Caballero, Luis; Nieto, Antonio; Dalmau, Jaime

    2008-03-01

    Children with short bowel syndrome (SBS) undergo frequent operations, so they are at risk for sensitizing to latex. There have been isolated reports of sensitization to food in these children. In a cross-sectional study, we assessed sensitization to latex, cow's milk, and egg with skin prick tests (SPT) and serum-specific immunoglobulin E (IgE) in 14 children with SBS. Data were collected about the number of operations with latex devices, serum total IgE, and history of feeding with milk formula. Ten children were sensitized to latex (specific IgE median: 6.7 kU/l, range: 0.5-33). Compared with those non-sensitized, sensitized children had significantly (p range: 0.5-21.1 kU/l), and five to egg (specific IgE median: 0.68, range: 0.58-2.17 kU/l). Except for some isolated days with cow's milk formula, the children had been initially fed with a diet without intact cow's milk proteins. Sensitization to latex, cow's milk, and egg is very frequent in children with SBS. They should be treated in a latex-free environment since the very early stages of the disease, and should be routinely studied regarding food sensitization, as this might contribute as an added factor in the chronic diarrhea of these patients.

  15. Three brief assessments of math achievement.

    Science.gov (United States)

    Steiner, Eric T; Ashcraft, Mark H

    2012-12-01

    Because of wide disparities in college students' math knowledge-that is, their math achievement-studies of cognitive processing in math tasks also need to assess their individual level of math achievement. For many research settings, however, using existing math achievement tests is either too costly or too time consuming. To solve this dilemma, we present three brief tests of math achievement here, two drawn from the Wide Range Achievement Test and one composed of noncopyrighted items. All three correlated substantially with the full achievement test and with math anxiety, our original focus, and all show acceptable to excellent reliability. When lengthy testing is not feasible, one of these brief tests can be substituted.

  16. Math Anxiety and Math Ability in Early Primary School Years

    Science.gov (United States)

    Krinzinger, Helga; Kaufmann, Liane; Willmes, Klaus

    2009-01-01

    Mathematical learning disabilities (MLDs) are often associated with math anxiety, yet until now, very little is known about the causal relations between calculation ability and math anxiety during early primary school years. The main aim of this study was to longitudinally investigate the relationship between calculation ability, self-reported…

  17. 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 migh...... 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....

  18. Residual monomer reduction in polymer latex products by extraction with supercritical carbon dioxide

    NARCIS (Netherlands)

    Aerts, M.; Meuldijk, J.; Kemmere, M.F.; Keurentjes, J.T.F.

    2011-01-01

    Extraction of residual monomer from a latex product with supercritical carbon dioxide ((sc)CO2) in a column was studied. Operating conditions were chosen at 35¿°C and 100 bar. For reducing the residual styrene level in a polystyrene latex from 104 ppm to 100¿ppm and from 104 ppm to 10¿ppm, a

  19. Incidence of latex harvesting technologies on agronomic and ...

    African Journals Online (AJOL)

    parameters and profitability of some rapid metabolic class clones of rubber ... of hormonal stimulation had no negative influence on the vegetative growth ..... yield (2597) was obtained with the control ..... metabolic energy of latex vessels as.

  20. Dr Math at your service

    CSIR Research Space (South Africa)

    Butgereit, L

    2012-10-01

    Full Text Available In this presentation the author explains how the Dr Math service works; how tutors are recruited to act as Dr Math; and how school pupils can reach Dr Math for help with their mathematics homework....

  1. 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.

  2. Comparative evaluation of Type 1 latex hypersensitivity in patients with chronic urticaria, rubber factory workers and healthy control subjects

    NARCIS (Netherlands)

    Piskin, Gamze; Akyol, Aynur; Uzar, Hatice; Tulek, Necla; Boyvat, Ayse; Gurgey, Erbak

    2003-01-01

    Latex hypersensitivity manifests itself most commonly with contact urticaria. In this study, we investigated the frequency of latex hypersensitivity as a possible aetiological factor in patients with chronic urticaria (CU) and compared latex hypersensitivity of CU patients (n = 50) with that of

  3. Mathematics anxiety: separating the math from the anxiety.

    Science.gov (United States)

    Lyons, Ian M; Beilock, Sian L

    2012-09-01

    Anxiety about math is tied to low math grades and standardized test scores, yet not all math-anxious individuals perform equally poorly in math. We used functional magnetic resonance imaging to separate neural activity during the anticipation of doing math from activity during math performance itself. For higher (but not lower) math-anxious individuals, increased activity in frontoparietal regions when simply anticipating doing math mitigated math-specific performance deficits. This network included bilateral inferior frontal junction, a region involved in cognitive control and reappraisal of negative emotional responses. Furthermore, the relation between frontoparietal anticipatory activity and highly math-anxious individuals' math deficits was fully mediated (or accounted for) by activity in caudate, nucleus accumbens, and hippocampus during math performance. These subcortical regions are important for coordinating task demands and motivational factors during skill execution. Individual differences in how math-anxious individuals recruit cognitive control resources prior to doing math and motivational resources during math performance predict the extent of their math deficits. This work suggests that educational interventions emphasizing control of negative emotional responses to math stimuli (rather than merely additional math training) will be most effective in revealing a population of mathematically competent individuals, who might otherwise go undiscovered.

  4. Changes in Math Prerequisites and Student Performance in Business Statistics: Do Math Prerequisites Really Matter?

    OpenAIRE

    Jeffrey J. Green; Courtenay C. Stone; Abera Zegeye; Thomas A. Charles

    2007-01-01

    We use a binary probit model to assess the impact of several changes in math prerequisites on student performance in an undergraduate business statistics course. While the initial prerequisites did not necessarily provide students with the necessary math skills, our study, the first to examine the effect of math prerequisite changes, shows that these changes were deleterious to student performance. Our results helped convince the College of Business to change the math prerequisite again begin...

  5. Studied on Virgin Coconut Oil (VCO) and Olive Oil (OO) as an Alternative for Stabilizer of Radiation Vulcanized Natural Rubber Latex (RVNRL) Preparation

    International Nuclear Information System (INIS)

    Syuhada Ramli; Sofian Ibrahim; Mohd Noorwadi Mat Lazim

    2016-01-01

    This paper presents the effects of virgin coconut oil (VCO) and olive oil (OO) as an alternative stabilizer in the radiation vulcanized natural rubber latex (RVNRL). Potassium laurite (KL) as a stabilizer considered as a control of RVNRL sample were compared to mixed ratio 1:1 KL: VCO and 1:1 KL: OO stabilizer formulation. Total solid content (TSC) and tensile strength (TS) results showed no significant different between the formulations. Mechanical stability time (MST) indicates higher stability of RVNRL with addition of VCO. The fatty acid composition in VCO indicate VCO was acting well as stabilizer for latex stabilizer formulation. (author)

  6. Extractable protein of radiation vulcanized natural rubber latex

    International Nuclear Information System (INIS)

    Soebianto, Y.S.; Upul, R.M.; Makuuchi, K.; Yoshii, F.; Kume, T.

    2000-01-01

    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)

  7. 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)

  8. NR based curred latex material reclaimed with 2,2'-dibenzamidodiphenyldisulphide in truck tyre tread compound

    NARCIS (Netherlands)

    Rajan, V.V.; Dierkes, Wilma K.; Joseph, R.; Noordermeer, Jacobus W.M.

    2006-01-01

    It is observed that reclamation of natural rubber latex based rubber using 2,2'-dibenzamidodiphenyldisulphide as reclaiming agent is an optional methodology for recycling of waste latex rubber (WLR). For progressive replacement of virgin natural rubber by the reclaim, two alternatives curing system

  9. Effects of Math Anxiety and Perfectionism on Timed versus Untimed Math Testing in Mathematically Gifted Sixth Graders

    Science.gov (United States)

    Tsui, Joanne M.; Mazzocco, Michèle M. M.

    2009-01-01

    This study was designed to examine the effects of math anxiety and perfectionism on math performance, under timed testing conditions, among mathematically gifted sixth graders. We found that participants had worse math performance during timed versus untimed testing, but this difference was statistically significant only when the timed condition preceded the untimed condition. We also found that children with higher levels of either math anxiety or perfectionism had a smaller performance discrepancy during timed versus untimed testing, relative to children with lower levels of math anxiety or perfectionism. There were no statistically significant gender differences in overall test performance, nor in levels of math anxiety or perfectionism; however, the difference between performance on timed and untimed math testing was statistically significant for girls, but not for boys. Implications for educators are discussed. PMID:20084180

  10. Affective and motivational factors mediate the relation between math skills and use of math in everyday life

    NARCIS (Netherlands)

    Jansen, B.R.J.; Schmitz, E.A.; van der Maas, H.L.J.

    2016-01-01

    This study focused on the use of math in everyday life (the propensity to recognize and solve quantitative issues in real life situations). Data from a Dutch nation-wide research on math among adults (N = 521) were used to investigate the question whether math anxiety and perceived math competence

  11. Addressing Math Anxiety in the Classroom

    Science.gov (United States)

    Finlayson, Maureen

    2014-01-01

    In today's educational systems, students of all levels of education experience math anxiety. Furthermore, math anxiety is frequently linked to poor achievement in mathematics. The purpose of this study is to examine the causes of math anxiety and to explore strategies which pre-service teachers have identified to overcome math anxiety. The…

  12. Cognitive Prediction of Reading, Math, and Attention: Shared and Unique Influences.

    Science.gov (United States)

    Peterson, Robin L; Boada, Richard; McGrath, Lauren M; Willcutt, Erik G; Olson, Richard K; Pennington, Bruce F

    The current study tested a multiple-cognitive predictor model of word reading, math ability, and attention in a community-based sample of twins ages 8 to 16 years ( N = 636). The objective was to identify cognitive predictors unique to each skill domain as well as cognitive predictors shared among skills that could help explain their overlap and thus help illuminate the basis for comorbidity of related disorders (reading disability, math disability, and attention deficit hyperactivity disorder). Results indicated that processing speed contributes to the overlap between reading and attention as well as math and attention, whereas verbal comprehension contributes to the overlap between reading and math. There was no evidence that executive functioning skills help account for covariation among these skill domains. Instead, specific executive functions differentially related to certain outcomes (i.e., working memory to math and inhibition to attention). We explored whether the model varied in younger versus older children and found only minor differences. Results are interpreted within the context of the multiple deficit framework for neurodevelopmental disorders.

  13. Minimizing surgical skin incision scars with a latex surgical glove.

    Science.gov (United States)

    Han, So-Eun; Ryoo, Suk-Tae; Lim, So Young; Pyon, Jai-Kyung; Bang, Sa-Ik; Oh, Kap-Sung; Mun, Goo-Hyun

    2013-04-01

    The current trend in minimally invasive surgery is to make a small surgical incision. However, the excessive tensile stress applied by the retractors to the skin surrounding the incision often results in a long wound healing time and extensive scarring. To minimize these types of wound problems, the authors evaluated a simple and cost-effective method to minimize surgical incision scars based on the use of a latex surgical glove. The tunnel-shaped part of a powder-free latex surgical glove was applied to the incision and the dissection plane. It was fixed to the full layer of the dissection plane with sutures. The glove on the skin surface then was sealed with Ioban (3 M Health Care, St. Paul, MN, USA) to prevent movement. The operation proceeded as usual, with the retractor running through the tunnel of the latex glove. It was possible to complete the operation without any disturbance of the visual field by the surgical glove, and the glove was neither torn nor separated by the retractors. The retractors caused traction and friction during the operation, but the extent of damage to the postoperative skin incision margin was remarkably less than when the operation was performed without a glove. This simple and cost-effective method is based on the use of a latex surgical glove to protect the surgical skin incision site and improve the appearance of the postoperative scar. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  14. Gamma irradiator design concepts for radiation vulcanisation of natural rubber latex

    International Nuclear Information System (INIS)

    Aggarwal, K.S.; Muralidharan, P.; Apte, M.G.; Kalurkar, A.R.; Shah, B.M.

    1990-01-01

    Radiation vulcanisation of natural rubber latex (NRL) is a new and yet unproven technology and one which involves undefined problems of consumer acceptance and high degree of radiation risk. Therefore, the designer should take care that the initial capital cost of the plant is as low as possible to keep the unit processing cost low during the initial lean period of the product requirement by the market. Three irradiators to process natural rubber latex have been designed as per capacity requirement of the user. Their salient features are described. (author). 2 tabs., 24 figs

  15. Status RVNRL in German latex industry and its introduction to the European market

    International Nuclear Information System (INIS)

    Bez, W.

    1996-01-01

    Reasons to look for an alternative crosslinking system avoiding sulphur curing was the restrictive policy of the German Health Authorities concerning nitrosamines. It was concluded that radiation curing offers further advantages . By avoiding the accelerators, type IV allergy is excluded, cytotoxicity is minimised to a very low level, films have better clarity and when thoroughly leached higher electrical resistance. Treatment of waste give no SO sub 2 emissions by burning, no Zinc in the ashes and possibly better microbial degradation. A development was carried out to irradiate natural latex by electron beam with a Dynamitron equipment. It was found trimethylolpropanetrimethacrylate to be a suitable sensitizer. Because of to high prices this development was interrupted. For future application trials and efforts to introduce RVNRL in the market gamma ray radiated natural latex either from Batan, Indonesia or MINT, Malaysia are used. Mainly dipped goods were produce, but radiated natural latex has shown good results in other processes. During discussions with customers it has proved necessary to establish specifications for RVNRL. A serious problem using natural latex for the production of medical devices is the type I allergy. Attempts are made to dip surgical gloves, leach them thoroughly and control extractable proteins were reduced to the very low level of 6.5 μg/g. Out of 18 patients sensitive to natural latex protein wearing gloves made from RVNRL only six have shown a positive response. That means RVNRL could help to solve the protein allergy problem. Further developments on this line are scheduled

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

    OpenAIRE

    H Nabavizade; R Amin

    2007-01-01

    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 descr...

  17. Turning Negatives into Positives: The Role of an Instructional Math Course on Preservice Teachers' Math Beliefs

    Science.gov (United States)

    Looney, Lisa; Perry, David; Steck, Andy

    2017-01-01

    Teachers' beliefs about mathematics can play a role in their teaching effectiveness (Bandura, 1993). Negative attitudes toward math (e.g., math anxiety) or low self-efficacy beliefs for teaching math can act as barriers to the teaching process, impacting the achievement and math beliefs of students (Beilock, Gunderson, Ramirez, & Levine, 2010;…

  18. Helping Students Get Past Math Anxiety

    Science.gov (United States)

    Scarpello, Gary

    2007-01-01

    Math anxiety can begin as early as the fourth grade and peaks in middle school and high school. It can be caused by past classroom experiences, parental influences, and remembering poor past math performance. Math anxiety can cause students to avoid challenging math courses and may limit their career choices. It is important for teachers, parents…

  19. Group Activities for Math Enthusiasts

    Science.gov (United States)

    Holdener, J.; Milnikel, R.

    2016-01-01

    In this article we present three group activities designed for math students: a balloon-twisting workshop, a group proof of the irrationality of p, and a game of Math Bingo. These activities have been particularly successful in building enthusiasm for mathematics and camaraderie among math faculty and students at Kenyon College.

  20. CHEMICAL EXAMINATION OF JACK TREE LATEX AND

    Indian Academy of Sciences (India)

    and on Saponification yielded fatty acids, Volatile as well as non-volatile. The unsaponifiable portion on repeated crystallisation provided a crystal- line, sharp melting compound which was identified as artostenone? from a. Latex (200 c.c.). ത്ത min- pe. Coagulum (A) Aqueous alcoholic solution (B). Acetone or ethyl acetate ...

  1. The space-math link in preschool boys and girls: Importance of mental transformation, targeting accuracy, and spatial anxiety.

    Science.gov (United States)

    Wong, Wang I

    2017-06-01

    Spatial abilities are pertinent to mathematical competence, but evidence of the space-math link has largely been confined to older samples and intrinsic spatial abilities (e.g., mental transformation). The roles of gender and affective factors are also unclear. This study examined the correlations between counting ability, mental transformation, and targeting accuracy in 182 Hong Kong preschoolers, and whether these relationships were weaker at higher spatial anxiety levels. Both spatial abilities related with counting similarly for boys and girls. Targeting accuracy also mediated the male advantage in counting. Interestingly, spatial anxiety moderated the space-math links, but differently for boys and girls. For boys, spatial abilities were irrelevant to counting at high anxiety levels; for girls, the role of anxiety on the space-math link is less clear. Results extend the evidence base of the space-math link to include an extrinsic spatial ability (targeting accuracy) and have implications for intervention programmes. Statement of contribution What is already known on this subject? Much evidence of a space-math link in adolescent and adult samples and for intrinsic spatial abilities. What does this study add? Extended the space-math link to include both intrinsic and extrinsic spatial abilities in a preschool sample. Showed how spatial anxiety moderated the space-math link differently for boys and girls. © 2016 The British Psychological Society.

  2. The Impact of MOVE IT Math(TM) and Traditional Textbook Instruction on Math Achievement Scores

    Science.gov (United States)

    Bennett, Angela Stephens

    2010-01-01

    One recommendation of government, education, and business leaders is an increased emphasis on math and science instruction in public schools. The purpose of this quantitative study using a posttest, quasi-experimental design was to determine if the Math Opportunities, Valuable Experiences, and Innovative Teaching (MOVE IT Math(TM)) program…

  3. 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.

  4. All Students Need Advanced Mathematics. Math Works

    Science.gov (United States)

    Achieve, Inc., 2013

    2013-01-01

    This fact sheet explains that to thrive in today's world, all students will need to graduate with very strong math skills. That can only mean one thing: advanced math courses are now essential math courses. Highlights of this paper include: (1) Advanced math equals college success; (2) Advanced math equals career opportunity; and (3) Advanced math…

  5. Efficacy of protection by latex gloves during orthodontic therapy.

    Science.gov (United States)

    Doll, G M; Zentner, A; Balan, R; Sergl, H G

    2000-01-01

    The wearing of gloves during orthodontic or dental treatment is generally indicated for reasons of hygiene and protection against infection. This study was aimed at determining the extent and localization of perforations caused by the various orthodontic treatment techniques and interrupting the infection barrier. The impermeability was tested by means of a water retention test according to European standard EN 455, Part 1, performed on 1600 Centramed (Centramed, Koblenz), Tekmedic and SafeEx non-sterile disposable latex gloves (both by Safe Med, Switzerland) and Safe Gan latex gloves with an additional acrylate coating (also by Safe Med). The perforation rate in unused gloves was between 0.5% and 7.5%, rising on average to 11% with increasing use. 36% of the total number of lesions resulted from handling removable appliances, and 57% from handling fixed appliances, especially when replacing arch wires and elastics. Most lesions were in the thumb, index finger and palm region. Only 18% of the defects were noticed by the dentists themselves. The gloves worn by beginners in their first year of postgraduate orthodontic training had about twice as many defects as those worn by qualified orthodontists. When patients with an increased risk of infection are to be treated, additional hand disinfection measures should be taken and 2 pairs of gloves worn in view of the relatively unreliable protection offered by commercially available latex gloves.

  6. Addressing the Math-Practice Gap in Elementary School: Are Tablets a Feasible Tool for Informal Math Practice?

    Science.gov (United States)

    Stacy, Sara T; Cartwright, Macey; Arwood, Zjanya; Canfield, James P; Kloos, Heidi

    2017-01-01

    Students rarely practice math outside of school requirements, which we refer to as the "math-practice gap". This gap might be the reason why students struggle with math, making it urgent to develop means by which to address it. In the current paper, we propose that math apps offer a viable solution to the math-practice gap: Online apps can provide access to a large number of problems, tied to immediate feedback, and delivered in an engaging way. To substantiate this conversation, we looked at whether tablets are sufficiently engaging to motivate children's informal math practice. Our approach was to partner with education agencies via a community-based participatory research design. The three participating education agencies serve elementary-school students from low-SES communities, allowing us to look at tablet use by children who are unlikely to have extensive access to online math enrichment programs. At the same time, the agencies differed in several structural details, including whether our intervention took place during school time, after school, or during the summer. This allowed us to shed light on tablet feasibility under different organizational constraints. Our findings show that tablet-based math practice is engaging for young children, independent of the setting, the student's age, or the math concept that was tackled. At the same time, we found that student engagement was a function of the presence of caring adults to facilitate their online math practice.

  7. An Investigation on Elementary School Students' Level of Math Learning, Using Math E-Books (A Case Study: Pishtazan Computer Primary School, 4th Zone of Tehran

    Directory of Open Access Journals (Sweden)

    Arezoo Naseri

    2016-11-01

    Full Text Available Since the focus on technology exists in all schools and classes, teachers need to know how to apply it in their teaching practices. The use of ICT in education is an undeniable necessity. Since the use of information and communication technology can smooth the paths of teaching-learning process for students, the researchers in this study tried to apply one of the information and communication technology tools, called electronic books (E-books in teaching math. The aim of this study is to examine elementary school students' level of math learning, using math e-books with the focus on teaching multiplication (Case Study: Pishtazan computer primary school, the 4th zone of Tehran. Using a quasi-experimental study, 61 third grade students from two primary schools for girls located in the 4th education zone of Tehran were selected. Math tests were used to collect data. Using T-test for independent samples, the results showed that level of math learning was higher in the students who have been trained with the help of e-book, compared to the students who have been trained through traditional teaching method.

  8. The Single-Item Math Anxiety Scale: An Alternative Way of Measuring Mathematical Anxiety

    Science.gov (United States)

    Núñez-Peña, M. Isabel; Guilera, Georgina; Suárez-Pellicioni, Macarena

    2014-01-01

    This study examined whether the Single-Item Math Anxiety Scale (SIMA), based on the item suggested by Ashcraft, provided valid and reliable scores of mathematical anxiety. A large sample of university students (n = 279) was administered the SIMA and the 25-item Shortened Math Anxiety Rating Scale (sMARS) to evaluate the relation between the scores…

  9. Assessment of the mutagenic and antimutagenic activity of Synadenium umbellatum Pax latex by micronucleus test in mice

    Directory of Open Access Journals (Sweden)

    PR. Melo-Reis

    Full Text Available Synadenium umbellatum Pax, popularly known as "cola-nota", is a medicinal plant that grows in tropical regions. The latex of this plant is used against various diseases, such as diabetes mellitus, leprosy, tripanosomiasis, leukemia, and several malignant tumors. The mutagenic, antimutagenic, and cytotoxic effects of the latex of this plant were investigated by measuring the frequency of micronuclei in mice bone marrow cells. To evaluate mutagenicity, the animals were treated with four doses of latex (10, 30, 50, and 100 mg/kg body weight. To study the antimutagenic activity, the animals were simultaneously treated with latex and mitomycin C (4 mg/kg. The cytotoxicity was evaluated by polychromatic and normochromatic erythrocytes ratio. Our results showed a significant increase of frequency of micronucleated polychromatic erythrocytes (MNPCE compared to the negative control group (p 0.05 was detected at the doses of 50 and 100 mg/kg. Under our experimental conditions, the results obtained indicate strong mutagenic and cytotoxic activity of S. umbellatum latex except the dose of 10 mg/kg and moderate antimutagenic effect at lower doses.

  10. The role of expressive writing in math anxiety.

    Science.gov (United States)

    Park, Daeun; Ramirez, Gerardo; Beilock, Sian L

    2014-06-01

    Math anxiety is a negative affective reaction to situations involving math. Previous work demonstrates that math anxiety can negatively impact math problem solving by creating performance-related worries that disrupt the working memory needed for the task at hand. By leveraging knowledge about the mechanism underlying the math anxiety-performance relationship, we tested the effectiveness of a short expressive writing intervention that has been shown to reduce intrusive thoughts and improve working memory availability. Students (N = 80) varying in math anxiety were asked to sit quietly (control group) prior to completing difficulty-matched math and word problems or to write about their thoughts and feelings regarding the exam they were about to take (expressive writing group). For the control group, high math-anxious individuals (HMAs) performed significantly worse on the math problems than low math-anxious students (LMAs). In the expressive writing group, however, this difference in math performance across HMAs and LMAs was significantly reduced. Among HMAs, the use of words related to anxiety, cause, and insight in their writing was positively related to math performance. Expressive writing boosts the performance of anxious students in math-testing situations. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  11. Using Brief Guided Imagery to Reduce Math Anxiety and Improve Math Performance: A Pilot Study

    Science.gov (United States)

    Henslee, Amber M.; Klein, Brandi A.

    2017-01-01

    The objective of this study was to investigate whether brief guided imagery could provide a short-term reduction in math anxiety and improve math performance. Undergraduates (N = 581) were screened for math anxiety, and the highest and lowest quartiles were recruited to participate in a lab-based study. Participants were assigned to a brief guided…

  12. Effects of radio sensitizers in the vulcanization of natural rubber latex induced by gamma radiation

    International Nuclear Information System (INIS)

    Souza, A. de; Canavel, V.; Araujo, S.C. de; Guedes, S.M.L.

    1992-01-01

    The effect of C Cl 4 and n-butyl acrylate as a sensitizer for radiation vulcanization of 60% DRC natural rubber latex with gamma rays, was studied relating tensile strength of vulcanized latex. The vulcanization dose is 200 kGy for natural rubber latex and it decreases to 40 kGy and to 9 kGy in the presence of C Cl 4 / potassium laureate and n-butyl acrylate / t-butyl hydroperoxide, respectively. The H 2 O 2 as a co-sensitizer does not change the efficiency of the combination of these sensitizers. The IV spectra show the formation of C=O after the irradiation as consequence of oxidation reactions. (author)

  13. Optical response of a flat metallic surface coated with a monolayer array of latex spheres

    International Nuclear Information System (INIS)

    Shi Lei; Liu Xiaohan; Yin Haiwei; Zi Jian

    2010-01-01

    We report on the fabrication, characterization and simulation of a structure consisting of a flat metallic surface coated with a monolayer array of latex spheres. This structure shows interesting optical response: over flat metallic surfaces a series of reflection minima appear in reflection spectra. Numerical simulations revealed that the structure can support two types of surface modes: surface plasmon-polaritons bound at the metallic surface and guided modes confined to the array of latex spheres, or their hybrids. Both experimental and theoretical results indicated that these surface modes show well-defined band structures due to the introduced periodicity by the monolayer array of latex spheres.

  14. Math and Movement: Practical Ways to Incorporate Math into Physical Education

    Science.gov (United States)

    Wade, Marcia

    2016-01-01

    Each year, physical educators are asked to incorporate even more math, language arts, science and social studies into their curriculum. The challenge is how to do this without sacrificing the essential health and life skills provided by a quality physical education program. One program, Math & Movement, is a great aid for physical educators to…

  15. Engaging Math-Avoidant College Students

    Directory of Open Access Journals (Sweden)

    M. Paul Latiolais

    2009-07-01

    Full Text Available This paper is an informal, personal account of how we, as two college teachers, became interested in math anxiety, decided to explore it amongst students at our institution in order to inform our teaching, and became convinced that the massive problem is math avoidance. We tried discussion groups, but few students attended, although those that did made useful suggestions. Thus informed, we designed an innovative course, Confronting College Mathematics as a Humanities course with the possibility of credit toward the math requirement, but it was undersubscribed in its first offering and had to be canceled. How can we get college students who avoid math to break through the barrier of math avoidance? We have now begun to explore a new approach: Second Life, where students can engage math—and quantitative literacy—virtually, and anonymously.

  16. Gender Compatibility, Math-Gender Stereotypes, and Self-Concepts in Math and Physics

    Science.gov (United States)

    Koul, Ravinder; Lerdpornkulrat, Thanita; Poondej, Chanut

    2016-01-01

    Positive self-assessment of ability in the quantitative domains is considered critical for student participation in science, technology, engineering, and mathematics field studies. The present study investigated associations of gender compatibility (gender typicality and contentedness) and math-gender stereotypes with self-concepts in math and…

  17. Development assessment of natural latex membranes: a new proposal for the treatment of amblyopia

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Jaqueline Alves; Rosa, Suelia Rodrigues Fleury, E-mail: jackalvesribeiro@gmail.com [Laboratorio de Engenharia e Biomaterial (BioEngLab), Faculdade Gama, Universidade de Brasilia (UnB), DF (Brazil); Leite, Cicilia Raquel Maia; Vasconcelos, Claudio Lopes; Soares, Joao Maria [Universidade do Estado do Rio Grande do Norte (UERN), Mossoro, RN (Brazil)

    2017-05-15

    The ophthalmic dysfunction amblyopia, commonly known as lazy eye, is characterized by decreased vision in one eye due to improper development in childhood. The aim of this study was to obtain and characterize natural rubber membranes and to assess their utility as an eye film capable of altering the passage of light. The latex membranes were produced using the Van Gogh method and the deposition technique and were analyzed by physical and chemical methods to determine the properties of latex in natura and of natural rubber membranes. The materials were characterized by X-ray diffractometry, scanning electron microscopy, thermogravimetry, differential scanning calorimetry, analysis of water sorption and light crossing analysis. We report here a new approach to the treatment of patients with amblyopia using latex membranes. (author)

  18. Development assessment of natural latex membranes: a new proposal for the treatment of amblyopia

    International Nuclear Information System (INIS)

    Ribeiro, Jaqueline Alves; Rosa, Suelia Rodrigues Fleury; Leite, Cicilia Raquel Maia; Vasconcelos, Claudio Lopes; Soares, Joao Maria

    2017-01-01

    The ophthalmic dysfunction amblyopia, commonly known as lazy eye, is characterized by decreased vision in one eye due to improper development in childhood. The aim of this study was to obtain and characterize natural rubber membranes and to assess their utility as an eye film capable of altering the passage of light. The latex membranes were produced using the Van Gogh method and the deposition technique and were analyzed by physical and chemical methods to determine the properties of latex in natura and of natural rubber membranes. The materials were characterized by X-ray diffractometry, scanning electron microscopy, thermogravimetry, differential scanning calorimetry, analysis of water sorption and light crossing analysis. We report here a new approach to the treatment of patients with amblyopia using latex membranes. (author)

  19. Effect of gamma radiation dose and sensitizer on the physical properties of irradiated natural rubber latex

    International Nuclear Information System (INIS)

    Komgrit, R.; Thawat, C.; B, Tripob; Wirach, T.

    2009-07-01

    Full text: The vulcanization of natural rubber latex can be induced by gamma radiation, which enhances cross-linking within the rubber matrix. The purpose of this research is to investigate the effect of gamma radiation dose and sensitizers on the physical properties of irradiated natural rubber. Three sensitizers n-butyl acrylate (n-B A), tetrachloroethylene (C 2 Cl 4 ) and trichloromethane (CHCl 3 ) were mixed with natural rubber latex before irradiation with gamma ray dose varied from 14 to 22 kGy. Results showed that the mixture of three sensitizers with specific ratios effectively induced the cross-linking of natural rubber latex. The cross-linking ratio and improved physical properties increased with increasing gamma dose. Therefore, the mixture ratios of n-B A, C 2 Cl 4 and CHCl 3 have shown to be a critical parameter in the vulcanization of natural rubber latex by gamma radiation

  20. The Synthesis and Modification of Nanosized Clickable Latex Particles

    KAUST Repository

    Almahdali, Sarah

    2013-01-01

    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

  1. Avoiding math on a rapid timescale: Emotional responsivity and anxious attention in math anxiety.

    Science.gov (United States)

    Pizzie, Rachel G; Kraemer, David J M

    2017-11-01

    Math anxiety (MA) is characterized by negative feelings towards mathematics, resulting in avoidance of math classes and of careers that rely on mathematical skills. Focused on a long timescale, this research may miss important cognitive and affective processes that operate moment-to-moment, changing rapid reactions even when a student simply sees a math problem. Here, using fMRI with an attentional deployment paradigm, we show that MA influences rapid spontaneous emotional and attentional responses to mathematical stimuli upon brief presentation. Critically, participants viewed but did not attempt to solve the problems. Indicating increased threat reactivity to even brief presentations of math problems, increased MA was associated with increased amygdala response during math viewing trials. Functionally and anatomically defined amygdala ROIs yielded similar results, indicating robustness of the finding. Similar to the pattern of vigilance and avoidance observed in specific phobia, behavioral results of the attentional paradigm demonstrated that MA is associated with attentional disengagement for mathematical symbols. This attentional avoidance is specific to math stimuli; when viewing negatively-valenced images, MA is correlated with attentional engagement, similar to other forms of anxiety. These results indicate that even brief exposure to mathematics triggers a neural response related to threat avoidance in highly MA individuals. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. The neurodevelopmental basis of math anxiety.

    Science.gov (United States)

    Young, Christina B; Wu, Sarah S; Menon, Vinod

    2012-05-01

    Math anxiety is a negative emotional reaction to situations involving mathematical problem solving. Math anxiety has a detrimental impact on an individual's long-term professional success, but its neurodevelopmental origins are unknown. In a functional MRI study on 7- to 9-year-old children, we showed that math anxiety was associated with hyperactivity in right amygdala regions that are important for processing negative emotions. In addition, we found that math anxiety was associated with reduced activity in posterior parietal and dorsolateral prefrontal cortex regions involved in mathematical reasoning. Multivariate classification analysis revealed distinct multivoxel activity patterns, which were independent of overall activation levels in the right amygdala. Furthermore, effective connectivity between the amygdala and ventromedial prefrontal cortex regions that regulate negative emotions was elevated in children with math anxiety. These effects were specific to math anxiety and unrelated to general anxiety, intelligence, working memory, or reading ability. Our study identified the neural correlates of math anxiety for the first time, and our findings have significant implications for its early identification and treatment.

  3. Partial swelling of latex particles by two monomers

    NARCIS (Netherlands)

    Noel, E.F.J.; Maxwell, I.A.; German, A.L.

    1993-01-01

    The swelling of polymeric latex particles with solvent and monomer is of great importance for the emulsion polymn. process in regard to compn. drift and rate of polymn. For the monomer combination, Me acrylate-vinyl acetate, both satn. and partial swelling were detd. exptl. Theories for satn.

  4. String Math 2017

    CERN Document Server

    The series of String-Math conferences has developed into a central event on the interface between mathematics and physics related to string theory, quantum field theory and neighboring subjects. The conference will take place from July 24-28 in the main building of Hamburg university. The String-Math conference is organised by the University of Hamburg jointly with DESY Hamburg.

  5. Basic Maths Practice Problems For Dummies

    CERN Document Server

    Beveridge, Colin

    2012-01-01

    Fun, friendly coaching and all the practice you need to tackle maths problems with confidence and ease In his popular Basic Maths For Dummies, professional maths tutor Colin Beveridge proved that he could turn anyone - even the most maths-phobic person - into a natural-born number cruncher. In this book he supplies more of his unique brand of maths-made- easy coaching, plus 2,000 practice problems to help you master what you learn. Whether you're prepping for a numeracy test or an employability exam, thinking of returning to school, or you'd just like to be one of those know-it-alls who says

  6. Attentional bias in math anxiety.

    Science.gov (United States)

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms.

  7. Latex Imaging by Environmental STEM: Application to the Study of the Surfactant Outcome in Hybrid Alkyd/Acrylate Systems

    OpenAIRE

    Faucheu , Jenny; Chazeau , Laurent; Gauthier , Catherine; Cavaille , Jean-Yves; Goikoetxea , Monika; Minari , Roque; Asua , Jose M.

    2009-01-01

    International audience; Among other uses. latexes are a successful alternative to solvent-borne binders for coatings. Efforts are made to produce hybrid nanostructured latexes containing an acrylic phase and an alkyd phase, However, after the film-forming process, the surfactant used to stabilize these latexes remains in the film, and its location can have a drastic effect on the application properties. Among the processing parameters, the alkyd hydrophobicity can strongly influence this loca...

  8. Association between individual differences in non-symbolic number acuity and math performance: a meta-analysis.

    Science.gov (United States)

    Chen, Qixuan; Li, Jingguang

    2014-05-01

    Many recent studies have examined the association between number acuity, which is the ability to rapidly and non-symbolically estimate the quantity of items appearing in a scene, and symbolic math performance. However, various contradictory results have been reported. To comprehensively evaluate the association between number acuity and symbolic math performance, we conduct a meta-analysis to synthesize the results observed in previous studies. First, a meta-analysis of cross-sectional studies (36 samples, N = 4705) revealed a significant positive correlation between these skills (r = 0.20, 95% CI = [0.14, 0.26]); the association remained after considering other potential moderators (e.g., whether general cognitive abilities were controlled). Moreover, a meta-analysis of longitudinal studies revealed 1) that number acuity may prospectively predict later math performance (r = 0.24, 95% CI = [0.11, 0.37]; 6 samples) and 2) that number acuity is retrospectively correlated to early math performance as well (r = 0.17, 95% CI = [0.07, 0.26]; 5 samples). In summary, these pieces of evidence demonstrate a moderate but statistically significant association between number acuity and math performance. Based on the estimated effect sizes, power analyses were conducted, which suggested that many previous studies were underpowered due to small sample sizes. This may account for the disparity between findings in the literature, at least in part. Finally, the theoretical and practical implications of our meta-analytic findings are presented, and future research questions are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Classroom Learning Environment and Gender: Do They Explain Math Self-Efficacy, Math Outcome Expectations, and Math Interest during Early Adolescence?

    Science.gov (United States)

    Deacon, Mary M.

    2011-01-01

    Despite initiatives to increase and broaden participation in science, technology, engineering, and mathematics (STEM) fields, women remain underrepresented in STEM. While U.S. girls and women perform as well as, if not better, than boys and men in math, research results indicate that there are significant declines in girls' math self-efficacy,…

  10. An investigation of boys’ and girls’ emotional experience of math, their math performance, and the relation between these variables

    NARCIS (Netherlands)

    Erturan, S; Jansen, B.

    2015-01-01

    GGender differences in children’s emotional experience of math, their math performance, and the relation between these variables were investigated in two studies. In Study 1, test anxiety, math anxiety, and math performance (whole-number computation) were measured in 134 children in grades 3-8 (ages

  11. Pilot Scale Production of Irradiated Natural Rubber Latex and its Dipping Products

    Directory of Open Access Journals (Sweden)

    M. Utama

    2005-07-01

    Full Text Available One hundred and fifty kg natural rubber latex (NRL before and after concentration were added with 3 phr (part hundred ratio of rubber normal butyl acrylate, then the mixture were irradiated at 25 kGy by gamma rays of 60Co in pilot scale. The irradiated natural rubber latex (INRL were then being to use for producing rubber products such as condom, surgical gloves, and spygmomanometer in factory scale. The quality of INRL and rubber products such as : total solid content (TSC, dry rubber content (DRC, KOH, VFA and MST number, tensile strength, modulus, elongation at break, extractable protein content, and response against Type I allergy etc. were evaluated. The economic aspect for producing INRL by means of Gamma Irradiator (GI and Electron Beam Machine (EBM such as payback period (PP, net present value (NPV and internal rate return (IRR were calculated. The results showed that the latex properties of INRL such as DRC, TSC, KOH, VFA, and MST number are not only found to the requirement of the ISO 2004 standard but also the latex has low protein, lipid, and carbohydrate content. The physical and mechanical properties (tensile strength, modulus, and elongation at break of rubber dipping products such as condom, gloves, and sphygmomanometer are not only found to the requirement of ISO 4074, ISO 10282, and ANSI/AAMI SP-1994 standards, but also the allergic response tested clinical latex-sensitive protein allergen by ELISA test on gloves, and by SPT test on condom are found to be negative. It indicates that production of INRL or PVNRL or RVNRL by EBM 250 keV/10 mA, was more cheap than by using gamma γ irradiator 200 kCi, or sulfur vulcanization. The value of PBP (payback period was 2,1 years, NPV (net present value was 4,250 US $, PI (profitability index 1,06 and IRR (internal rate of returns was 25,0%.

  12. A descriptive study of high school Latino and Caucasian students' values about math, perceived math achievement and STEM career choice

    Science.gov (United States)

    Rodriguez Flecha, Samuel

    The purpose of this study was to examine high school students' math values, perceived math achievement, and STEM career choice. Participants (N=515) were rural high school students from the U.S. Northwest. Data was collected by administering the "To Do or Not to Do:" STEM pilot survey. Most participants (n=294) were Latinos, followed by Caucasians (n=142). Fifty-three percent of the students rated their math achievement as C or below. Of high math students, 57% were male. Females were 53% of low math students. Caucasians (61%) rated themselves as high in math in a greater proportion than Latinos (39%). Latinos (58%) rated themselves as low in math in a greater proportion than Caucasians (39%). Math Values play a significant role in students' perceived math achievement. Internal math values (r =.68, R2 =.46, p =.001) influenced perceived math achievement regardless of gender (males: r =.70, R2 =.49, p =.001; females: r =.65, R2 =.43, p =.001), for Latinos (r =.66, R2 =.44, p =.001), and Caucasians (r =.72, R2 =.51, p =.001). External math values (r =.53, R2 =.28, p =.001) influenced perceived math achievement regardless of gender (males: r =.54, R2 =.30, p =.001; females: r =.49, R2 =.24, p =.001), for Latinos (r =.47, R2 =.22, p =.001), and Caucasians (r =.58, R2 =.33, p =.001). Most high-math students indicated an awareness of being good at math at around 11 years old. Low-math students said that they realized that math was difficult for them at approximately 13 years of age. The influence of parents, teachers, and peers may vary at different academic stages. Approximately half of the participants said there was not a person who had significantly impacted their career choice; only a minority said their parents and teachers were influencing them to a STEM career. Parents and teachers are the most influential relationships in students' career choice. More exposure to STEM role models and in a variety of professions is needed. Possible strategies to impact students

  13. Barron's SAT math workbook

    CERN Document Server

    Leff MS, Lawrence S

    2016-01-01

    This completely revised edition reflects all of the new questions and question types that will appear on the new SAT, scheduled to be administered in Spring 2016. Includes hundreds of revised math questions and answer explanations, math strategies, test-taking tips, and much more.

  14. Extractable protein content of radiation vulcanized natural rubber latex films

    International Nuclear Information System (INIS)

    Ma'zam Md Said; Wan Manshol Wan Zin

    1996-01-01

    The effects of processing conditions on extractable protein content of coagulant dipped radiation vulcanized natural rubber latex films have been investigated. Drying of wet-gel of radiation vulcanized latex films even at a relatively low temperature of 70 degree C resulted in increases of extractable protein content of the films. The extractable protein content is dependent upon both the temperature and time of drying of wet-gel deposit. Wet-gel leaching of film alone is not adequate to reduce the extractable protein content of films to low levels. Combination of wet-gel leaching, post-leaching, a dip in corn starch slurry, followed by drying at a low temperature of 70 degree C reduces the extractable protein content of films to very low levels

  15. [Anaphylactic reaction to latex during spinal anesthesia: a case report].

    Science.gov (United States)

    Ueda, Narumi; Kitamura, Rie; Wakamori, Takeshi; Nakamura, Kumi; Konishi, Keisuke

    2008-05-01

    A 46-year-old man, with a history of atopic dermatitis and bronchial asthma, underwent surgery for an inguinal hernia. Forty-three minutes subsequent to spinal anesthesia, the patient complained suddenly of dyspnea with wheezing. Blood pressure decreased and skin eruption was observed on his chest. Postoperative laboratory tests revealed high IgE concentration, and a skin test confirmed an allergy to latex. The patient's allergic reaction was easily overlooked because of his history of bronchial asthma and the possibility that the hypotension was caused by the high spinal anesthesia. Latex allergy should be considered in any suspicious case presenting with these symptoms during surgery. After recovery, a skin test should be used to confirm the allergy to avoid repeated allergic episodes.

  16. SAT math prep course

    CERN Document Server

    Kolby, Jeff

    2011-01-01

    Comprehensive Prep for SAT Math Every year, students pay 1,000 and more to test prep companies to prepare for the math section of the new SAT. Now you can get the same preparation in a book. Features: * Comprehensive Review: Twenty-three chapters provide complete review of SAT math. * Practice: Includes 164 examples and more than 500 exercises! Arranged from easy to medium to hard to very hard. * Diagnostic Test: The diagnostic test measures your strengths and weaknesses and directs you to areas you need to study more. * Performance: If your target is a 700+ score, this is the book!

  17. Math Is Like a Scary Movie? Helping Young People Overcome Math Anxiety

    Science.gov (United States)

    Kulkin, Margaret

    2016-01-01

    Afterschool teachers who tutor students or provide homework help have a unique opportunity to help students overcome the social or emotional barriers that so often block learning. They can embrace a creative and investigative approach to math learning. Margaret Kulkin's interest in being a math attitude "myth-buster" led her to apply to…

  18. The Effect of Neurocognitive Function on Math Computation in Pediatric ADHD: Moderating Influences of Anxious Perfectionism and Gender.

    Science.gov (United States)

    Sturm, Alexandra; Rozenman, Michelle; Piacentini, John C; McGough, James J; Loo, Sandra K; McCracken, James T

    2018-03-20

    Predictors of math achievement in attention-deficit/hyperactivity disorder (ADHD) are not well-known. To address this gap in the literature, we examined individual differences in neurocognitive functioning domains on math computation in a cross-sectional sample of youth with ADHD. Gender and anxiety symptoms were explored as potential moderators. The sample consisted of 281 youth (aged 8-15 years) diagnosed with ADHD. Neurocognitive tasks assessed auditory-verbal working memory, visuospatial working memory, and processing speed. Auditory-verbal working memory speed significantly predicted math computation. A three-way interaction revealed that at low levels of anxious perfectionism, slower processing speed predicted poorer math computation for boys compared to girls. These findings indicate the uniquely predictive values of auditory-verbal working memory and processing speed on math computation, and their differential moderation. These findings provide preliminary support that gender and anxious perfectionism may influence the relationship between neurocognitive functioning and academic achievement.

  19. Math Practice and Its Influence on Math Skills and Executive Functions in Adolescents with Mild to Borderline Intellectual Disability

    Science.gov (United States)

    Jansen, Brenda R. J.; De Lange, Eva; Van der Molen, Mariet J.

    2013-01-01

    Adolescents with mild to borderline intellectual disability (MBID) often complete schooling without mastering basic math skills, even though basic math is essential for math-related challenges in everyday life. Limited attention to cognitive skills and low executive functioning (EF) may cause this delay. We aimed to improve math skills in an…

  20. Mapping Changes in Students' English and Math Self-Concepts: A Latent Growth Model Study

    Science.gov (United States)

    King, Ronnel B.; McInerney, Dennis M.

    2014-01-01

    The aims of this study were to examine changes in students' English and math self-concepts and to investigate the effects of gender and school ability level on these changes. Self-concept in English and math were measured thrice across three years among a sample of 2618 secondary school students from Hong Kong. Gender and school ability level were…

  1. Enhancing Mathematical Communication for Virtual Math Teams

    Science.gov (United States)

    Stahl, Gerry; Çakir, Murat Perit; Weimar, Stephen; Weusijana, Baba Kofi; Ou, Jimmy Xiantong

    2010-01-01

    The Math Forum is an online resource center for pre-algebra, algebra, geometry and pre-calculus. Its Virtual Math Teams (VMT) service provides an integrated web-based environment for small teams of people to discuss math and to work collaboratively on math problems or explore interesting mathematical micro-worlds together. The VMT Project studies…

  2. Math-Gender Stereotypes in Elementary School Children

    Science.gov (United States)

    Cvencek, Dario; Meltzoff, Andrew N.; Greenwald, Anthony G.

    2011-01-01

    A total of 247 American children between 6 and 10 years of age (126 girls and 121 boys) completed Implicit Association Tests and explicit self-report measures assessing the association of (a) "me" with "male" (gender identity), (b) "male" with "math" (math-gender stereotype), and (c) "me" with "math" (math self-concept). Two findings emerged.…

  3. Radiation vulcanization of natural rubber latex using 250 keV electron beam machine

    Energy Technology Data Exchange (ETDEWEB)

    Chirinos, H.; Yoshii, F.; Makuuchi, K.; Lugao, A. E-mail: ablugao@net.ipen.br

    2003-08-01

    The sensitized radiation vulcanization of natural rubber latex has been carried out with 250 keV electrons. Latex was irradiated over a range of the beam current from 5 to 20 mA in the presence of sensitizers like the n-butyl acrylate (n-BA). The vulcanization dose decreases with increasing beam current condition. The rate of vulcanization (R{sub vul}) depends on the beam current (I) as given by the equation R{sub vul}=kI{sup 0.6}.

  4. An Investigation of Boys' and Girls' Emotional Experience of Math, Their Math Performance, and the Relation between These Variables

    Science.gov (United States)

    Erturan, Selin; Jansen, Brenda

    2015-01-01

    Gender differences in children's emotional experience of math, their math performance, and the relation between these variables were investigated in two studies. In Study 1, test anxiety, math anxiety, and math performance (whole-number computation) were measured in 134 children in grades 3-8 (ages 7-15 years). In Study 2, perceived math…

  5. Effects of Math Anxiety and Perfectionism on Timed versus Untimed Math Testing in Mathematically Gifted Sixth Graders

    Science.gov (United States)

    Tsui, Joanne M.; Mazzocco, Michele M. M.

    2006-01-01

    This study was designed to examine the effects of math anxiety and perfectionism on math performance, under timed testing conditions, among mathematically gifted sixth graders. We found that participants had worse math performance during timed versus untimed testing, but this difference was statistically significant only when the timed condition…

  6. Multidimensional assessment of self-regulated learning with middle school math students.

    Science.gov (United States)

    Callan, Gregory L; Cleary, Timothy J

    2018-03-01

    This study examined the convergent and predictive validity of self-regulated learning (SRL) measures situated in mathematics. The sample included 100 eighth graders from a diverse, urban school district. Four measurement formats were examined including, 2 broad-based (i.e., self-report questionnaire and teacher ratings) and 2 task-specific measures (i.e., SRL microanalysis and behavioral traces). Convergent validity was examined across task-difficulty, and the predictive validity was examined across 3 mathematics outcomes: 2 measures of mathematical problem solving skill (i.e., practice session math problems, posttest math problems) and a global measure of mathematical skill (i.e., standardized math test). Correlation analyses were used to examine convergent validity and revealed medium correlations between measures within the same category (i.e., broad-based or task-specific). Relations between measurement classes were not statistically significant. Separate regressions examined the predictive validity of the SRL measures. While controlling all other predictors, a SRL microanalysis metacognitive-monitoring measure emerged as a significant predictor of all 3 outcomes and teacher ratings accounted for unique variance on 2 of the outcomes (i.e., posttest math problems and standardized math test). Results suggest that a multidimensional assessment approach should be considered by school psychologists interested in measuring SRL. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  7. La maison des mathématiques

    CERN Document Server

    Villani, Cédric; Moncorgé, Vincent

    2014-01-01

    Comment travaillent les mathématiciens ? C'est peut-être en se promenant dans les couloirs de la première des " maisons des mathématiques " de France, l'institut Henri Poincaré, que l'on trouvera quelques réponses. Le mathématicien Cédric Villani et le physicien Jean-Philippe Uzan nous invitent à découvrir cette discipline et ses acteurs. Au fil des pages on suit, à travers de superbes images signées du photographe Vincent Moncorgé, la façon dont se fabrique cette science qui reste souvent mystérieuse. Toutes les dimensions, scientifique, esthétique et poétique, des mathématiques sont convoquées grâce à des regards croisés : la diversité des inspirations des chercheurs, la source de leur créativité, l'imaginaire littéraire et artistique des mathématiques, la drôle de tribu des mathématiciens. Un voyage au cœur de cette " auberge espagnole " des mathématiques, campus " à la française " accueillant des centaines de chercheurs du monde entier, devenu un lieu d'émulation et d'éc...

  8. Low field NMR study of the latex derived from Brosimum parinarioides - Moraceae

    International Nuclear Information System (INIS)

    Miguez, Eduardo; Tavares, Maria Ines B.

    2009-01-01

    Brosimum parinarioides is a tree found in the Amazonia forest and its latex (Leite de Amapa) is often used like food and by the popular medicine in the treatment of tuberculosis and asthma. Being swallowed in nature, its necessary determinate the stability degree of this latex in the storage conditions in which is used in Amazonia. The analyses of T 2 data showed that the limit of stability is not longer than six month in the storage conditions used by the population of Amazonia. The Low field NMR proved to be an efficient method for this kind of study. (author)

  9. An explanatory model of maths achievement:Perceived parental involvement and academic motivation.

    Science.gov (United States)

    Rodríguez, Susana; Piñeiro, Isabel; Gómez-Taibo, Mª L; Regueiro, Bibiana; Estévez, Iris; Valle, Antonio

    2017-05-01

    Although numerous studies have tried to explain performance in maths very few have deeply explored the relationship between different variables and how they jointly explain mathematical performance. With a sample of 897 students in 5th and 6th grade in Primary Education and using structural equation modeling (SEM), this study analyzes how the perception of parents’ beliefs is related to children´s beliefs, their involvement in mathematical tasks and their performance. Perceived parental involvement contributes to the motivation of their children in mathematics. Direct supervision of students’ academic work by parents may increase students’ concerns about the image and rating of their children, but not their academic performance. In fact, maths achievement depends directly and positively on the parents’ expectations and children’s maths self-efficacy and negatively on the parents’ help in tasks and performance goal orientation. Perceived parental involvement contributes to children’s motivation in maths essentially conveying confidence in their abilities and showing interest in their progress and schoolwork.

  10. Opportunities for Learning Math in Elementary School: Implications for SES Disparities in Procedural and Conceptual Math Skills

    Science.gov (United States)

    Bachman, Heather J.; Votruba-Drzal, Elizabeth; El Nokali, Nermeen E.; Castle Heatly, Melissa

    2015-01-01

    The present study examined whether multiple opportunities to learn math were associated with smaller socioeconomic status (SES) disparities in fifth-grade math achievement using data from the NICHD Study of Early Child Care and Youth Development (SECCYD; N = 1,364). High amounts of procedural math instruction were associated with higher…

  11. Developmental Math Programs in California Community College: An Analysis of Math Boot Camp at Cosumnes River College

    Science.gov (United States)

    Powell, Torence J.

    2017-01-01

    The California Community College system, as an open access institution, is tasked with helping students who possess math skills far below college-level complete math course requirements for obtaining an associate degree or transfer to a university. Colleges have created various developmental math programs to achieve this mission; this paper…

  12. Math anxiety and exposure to statistics in messages about genetically modified foods: effects of numeracy, math self-efficacy, and form of presentation.

    Science.gov (United States)

    Silk, Kami J; Parrott, Roxanne L

    2014-01-01

    Health risks are often communicated to the lay public in statistical formats even though low math skills, or innumeracy, have been found to be prevalent among lay individuals. Although numeracy has been a topic of much research investigation, the role of math self-efficacy and math anxiety on health and risk communication processing has received scant attention from health communication researchers. To advance theoretical and applied understanding regarding health message processing, the authors consider the role of math anxiety, including the effects of math self-efficacy, numeracy, and form of presenting statistics on math anxiety, and the potential effects for comprehension, yielding, and behavioral intentions. The authors also examine math anxiety in a health risk context through an evaluation of the effects of exposure to a message about genetically modified foods on levels of math anxiety. Participants (N = 323) were randomly assigned to read a message that varied the presentation of statistical evidence about potential risks associated with genetically modified foods. Findings reveal that exposure increased levels of math anxiety, with increases in math anxiety limiting yielding. Moreover, math anxiety impaired comprehension but was mediated by perceivers' math confidence and skills. Last, math anxiety facilitated behavioral intentions. Participants who received a text-based message with percentages were more likely to yield than participants who received either a bar graph with percentages or a combined form. Implications are discussed as they relate to math competence and its role in processing health and risk messages.

  13. Isolation rubber latex binary composites consisting of cotton and poly-N, N-dimethyl-N, N-diallilammony chloride

    Directory of Open Access Journals (Sweden)

    J. Cornejo Tueros

    2012-01-01

    Full Text Available The paper discusses the application of rubber from latex binary coagulating agent consisting of cotton - textile waste and polymeric quaternary ammonium salts. The influence on the process of extracting rubber from latex flow coagulating agent temsperatury and concentration of the dispersed phase.

  14. Effect of cellulose nanocrystals from corn cob with dispersion agent polyvinyl pyrrolidone in natural rubber latex film after aging treatment

    Science.gov (United States)

    Harahap, H.; Ridha, M.; Halimatuddahliana; Taslim; Iriany

    2018-02-01

    This study about the resistance of natural rubber latex films using nanocrystals cellulose filler from corn cob waste by aging treatment. Corn cob used as organic filler composed of cellulose, hemicellulose, and lignin. Each component has a potential for reuse, such as cellulose. Cellulose from corn cob has potential application as a filler prepared by hydrolysis process using a strong acid. The producing of natural rubber latex films through coagulant dowsing process. This research started with the pre-vulcanization process of natural rubber latex at 70 °C and followed by process of vulcanization at 110 °C for 20 minutes. Natural rubber latex films that have been produced continued with the aging treatment at 70 °C for 168 hours. The mechanical properties of natural rubber latex films after aging treatment are the tensile strength, elongation at break, M100 and M300 have performed.

  15. 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.

  16. Nitrogen removal from concentrated latex wastewater by land treatment

    Directory of Open Access Journals (Sweden)

    Vikanda Thongnuekhang

    2004-05-01

    Full Text Available Most of the concentrated latex factories in the South of Thailand discharge treated wastewater that contains high level of nitrogen to a nearby river or canals leading to a water pollution problem. A study of land treatment system was conducted to treat and utilize nitrogen in treated wastewater from the concentrated latex factory. The experimental pilot-scale land treatment system was constructed at the Faculty of Engineering, Prince of Songkla University, Hat Yai Campus. It consisted of water convolvulus (Ipomea aquatica, I. Reptans, tropical carpet grass (Axonopus compresus (Swartz Beav. and control unit (no plantation. The treated wastewater from the stabilization pond system of the selected concentrated latex factoryin Songkhla was used to irrigate each experimental unit. Influent and effluent from the experimental units were analyzed for TKN, NH3-N, Org-N, NO3 --N, NO2 --N, BOD5, sulfate, pH and EC. The land treatment system resulted a high removal efficiency for nitrogen. Tropical carpet grass provided higher removal efficiency than other units for all parameters. The removal efficiency of water convolvulus and control unit were not significantly different. The average removal efficiency of TKN, NH3-N, Org-N, BOD5 and sulfate for tropical carpet grass unit were 92, 97, 61, 88 and 52%, for water convolvulus unit were 75, 80, 43, 41 and 30%, and for control unit were 74, 80, 41, 31 and 28%, respectively. Mass balance of nitrogen transformation was conducted. It revealed that plant uptake was the major mechanism for nitrogen removal in land treatment.

  17. 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

  18. Les grands problèmes mathématiques ils orientent l'avenir des maths

    CERN Document Server

    2012-01-01

    Les mathématiques ont leurs sept merveilles ! Il s’agit des sept problèmes du millénaire, mis à prix à un million de dollars chacun par l’Institut Clay de mathématiques en 2000. Mais l’intelligence des mathématiciens est aussi mise à l’épreuve par bien d’autres problèmes, tels ceux de Hilbert. Découvrez dans ce numéro comment ces énigmes orientent l’avenir de la discipline ouvrant la voie à de nouvelles connaissances fondamentales.

  19. Math starters 5- to 10-minute activities aligned with the common core math standards, grades 6-12

    CERN Document Server

    Muschla, Judith A; Muschla, Erin

    2013-01-01

    A revised edition of the bestselling activities guide for math teachers Now updated with new math activities for computers and mobile devices-and now organized by the Common Core State Standards-this book includes more than 650 ready-to-use math starter activities that get kids quickly focused and working as soon as they enter the classroom. Ideally suited for any math curriculum, these high-interest problems spark involvement in the day's lesson, help students build skills, and allow teachers to handle daily management tasks without wasting valuable instructional time. A newly updated edit

  20. Math Growth Trajectories of Students with Disabilities: Disability Category, Gender, Racial, and Socioeconomic Status Differences from Ages 7 to 17

    Science.gov (United States)

    Wei, Xin; Lenz, Keith B.; Blackorby, Jose

    2013-01-01

    This study examined math growth trajectories by disability category, gender, race, and socioeconomic status using a nationally representative sample of students ages 7 to 17. The students represented 11 federal disability categories. Compared with the national norming sample, students in all 11 disability categories had lower math achievement…

  1. Multivariate Analysis of Students' Performance in Math Courses and Specific Engineering Courses

    OpenAIRE

    H. Naccache; R. Hleiss

    2016-01-01

    The aim of this research is to study the relationship between the performance of engineering students in different math courses and their performance in specific engineering courses. The considered courses are taken mainly by engineering students during the first two years of their major. Several factors are being studied, such as gender and final grades in the math and specific engineering courses. Participants of this study comprised a sample of more than thousands of engineering students a...

  2. Tensile properties of latex paint films with TiO2 pigment

    Science.gov (United States)

    Hagan, Eric W. S.; Charalambides, Maria N.; Young, Christina T.; Learner, Thomas J. S.; Hackney, Stephen

    2009-05-01

    The tensile properties of latex paint films containing TiO2 pigment were studied with respect to temperature, strain-rate and moisture content. The purpose of performing these experiments was to assist museums in defining safe conditions for modern paintings held in collections. The glass transition temperature of latex paint binders is in close proximity to ambient temperature, resulting in high strain-rate dependence in typical exposure environments. Time dependence of modulus and failure strain is discussed in the context of time-temperature superposition, which was used to extend the experimental time scale. Nonlinear viscoelastic material models are also presented, which incorporate a Prony series with the Ogden or Neo-Hookean hyperelastic function for different TiO2 concentrations.

  3. LaTeX - Know what you are missing

    Directory of Open Access Journals (Sweden)

    Gunther Maier

    2016-11-01

    Full Text Available This article gives a brief introduction to \\LaTeX\\ and related tools. The aim is to give an overview, to demonstrate the flexibility and versatility of the software, and to assist the reader taking first steps using it. The article links to a number of valuable resources for further information.

  4. Marine bacterial prodigiosin as dye for rubber latex, polymethyl ...

    African Journals Online (AJOL)

    Prodigiosin is known for its immunomodulatory, antibacterial, antimycotic, antimalarial, algicidal and anticancer activities. Here, we reported the evaluation of prodigiosin pigment as a dyeing agent in rubber latex, paper and polymethyl methacrylate (PMMA) so that it can be considered as an alternative to synthetic pigments.

  5. Choke or thrive? The relation between salivary cortisol and math performance depends on individual differences in working memory and math-anxiety.

    Science.gov (United States)

    Mattarella-Micke, Andrew; Mateo, Jill; Kozak, Megan N; Foster, Katherine; Beilock, Sian L

    2011-08-01

    In the current study, we explored how a person's physiological arousal relates to their performance in a challenging math situation as a function of individual differences in working memory (WM) capacity and math-anxiety. Participants completed demanding math problems before and after which salivary cortisol, an index of arousal, was measured. The performance of lower WM individuals did not depend on cortisol concentration or math-anxiety. For higher WM individuals high in math-anxiety, the higher their concentration of salivary cortisol following the math task, the worse their performance. In contrast, for higher WM individuals lower in math-anxiety, the higher their salivary cortisol concentrations, the better their performance. For individuals who have the capacity to perform at a high-level (higher WMs), whether physiological arousal will lead an individual to choke or thrive depends on math-anxiety. 2011 APA, all rights reserved

  6. Assessment of adverse reactions to latex gloves use among nurses ...

    African Journals Online (AJOL)

    ... to latex is a common problem among nurses and other health care workers. ... There was significant association between family history and occurrence of ... These effects may vary in severity from skin problems to anaphylactic shock.

  7. An Annotated Math Lab Inventory.

    Science.gov (United States)

    Schussheim, Joan Yares

    1980-01-01

    A listing of mathematics laboratory material is organized as follows: learning kits, tape programs, manipulative learning materials, publications, math games, math lab library, and an alphabetized listing of publishers and/or companies offering materials. (MP)

  8. Formation of Defect-Free Latex Films on Porous Fiber Supports

    KAUST Repository

    Lively, Ryan P.; Mysona, Joshua A.; Chance, Ronald R.; Koros, William J.

    2011-01-01

    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

  9. The construction and commissioning of MINT's latex irradiator

    International Nuclear Information System (INIS)

    Razali Hamzah; Muhd Khairi Muhd Said; Muhd Ariff Hamzah; Wan Manshol Wan Zin; Taiman Kadni

    1996-01-01

    The construction and installation of MINT's automatic continuous latex irradiator is described. MINT cooperated with NUKEM to design the plant. Construction was done by local building consultants and local contractor. The installation of the plant includes local fabrication components and imported components. The plant is automatically controlled by a computer system. Features of plant is described

  10. Enhancing Mathematical Communication for Virtual Math Teams

    Directory of Open Access Journals (Sweden)

    Gerry Stahl

    2010-06-01

    Full Text Available The Math Forum is an online resource center for pre-algebra, algebra, geometry and pre-calculus. Its Virtual Math Teams (VMT service provides an integrated web-based environment for small teams of people to discuss math and to work collaboratively on math problems or explore interesting mathematical micro-worlds together. The VMT Project studies the online math discourse that takes place during sessions of virtual math teams working on open-ended problem-solving tasks. In particular, it investigates methods of group cognition that are employed by teams in this setting. The VMT environment currently integrates social networking, synchronous text chat, a shared whiteboard for drawing, web browsers and an asynchronous wiki for exchanging findings within the larger community. A simple version of MathML is supported in the whiteboard, chat and wiki for displaying mathematical expressions. The VMT Project is currently integrating the dynamic mathematics application, GeoGebra, into its collaboration environment. This will create a multi-user version of GeoGebra, which can be used in concert with the chat, web browsers, curricular topics and wiki repository.

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

    Directory of Open Access Journals (Sweden)

    Jae-Woong Han

    2015-10-01

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

  12. Study of glucoamylase immobilization in butadiene nitrile latex membrane

    International Nuclear Information System (INIS)

    Miller, E.

    1992-01-01

    Attempts have been undetaken to immobilize glucoamylaze by means of butadiene nitrile latex in the presence of a chemical initiator and 60 Co γ-radiation. The activity, stability of conjugates in the membrane and permeability of oxygen in these membranes were determined. (author) 14 refs.; 5 figs

  13. 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.

  14. Evaluation of HeartMath Training Programme for Improving ...

    African Journals Online (AJOL)

    The goal of this study was to evaluate the influence of a HeartMath training apparatus on personal resilience and physiological coherence. A within group, pre-test and post-test, outcome evaluative design was employed to assess changes in dependent variables. A small convenience sample of 6 participants, 4 women and ...

  15. Worrying Thoughts Limit Working Memory Capacity in Math Anxiety.

    Science.gov (United States)

    Shi, Zhan; Liu, Peiru

    2016-01-01

    Sixty-one high-math-anxious persons and sixty-one low-math-anxious persons completed a modified working memory capacity task, designed to measure working memory capacity under a dysfunctional math-related context and working memory capacity under a valence-neutral context. Participants were required to perform simple tasks with emotionally benign material (i.e., lists of letters) over short intervals while simultaneously reading and making judgments about sentences describing dysfunctional math-related thoughts or sentences describing emotionally-neutral facts about the world. Working memory capacity for letters under the dysfunctional math-related context, relative to working memory capacity performance under the valence-neutral context, was poorer overall in the high-math-anxious group compared with the low-math-anxious group. The findings show a particular difficulty employing working memory in math-related contexts in high-math-anxious participants. Theories that can provide reasonable interpretations for these findings and interventions that can reduce anxiety-induced worrying intrusive thoughts or improve working memory capacity for math anxiety are discussed.

  16. Cost evaluation of radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    Makuuchi, K.

    2003-01-01

    Cost of radiation vulcanized NR latex was evaluated. The plant would be built in an existing dipping factory in an industrial area in a Southeast Asian country. One thousands dry tons of NR latex are vulcanized with a low energy electron accelerator. The electron accelerator is a self-shielding low energy type. The maximum accelerating voltage is 300 kV and the output power is 10 kW. The total construction cost of the plant is $400,000 including electron accelerator and other equipments. Costs of raw materials and utilities are $1.165 and $0.023 per one kg of product, respectively. The fixed costs of the plant consist of labor costs, labor overhead, maintenance, plant overhead, depreciation, and bank interest. It is $0.190/kg of product. The company overhead for operation including company management, R and D and insurance is $0.044/kg of product. Thus, the total production cost is estimated to be $1.422/kg of product. (author)

  17. Phylogeny of the TRAF/MATH domain.

    Science.gov (United States)

    Zapata, Juan M; Martínez-García, Vanesa; Lefebvre, Sophie

    2007-01-01

    The TNF-receptor associated factor (TRAF) domain (TD), also known as the meprin and TRAF-C homology (MATH) domain is a fold of seven anti-parallel p-helices that participates in protein-protein interactions. This fold is broadly represented among eukaryotes, where it is found associated with a discrete set of protein-domains. Virtually all protein families encompassing a TRAF/MATH domain seem to be involved in the regulation of protein processing and ubiquitination, strongly suggesting a parallel evolution of the TRAF/MATH domain and certain proteolysis pathways in eukaryotes. The restricted number of living organisms for which we have information of their genetic and protein make-up limits the scope and analysis of the MATH domain in evolution. However, the available information allows us to get a glimpse on the origins, distribution and evolution of the TRAF/MATH domain, which will be overviewed in this chapter.

  18. 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)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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)

  20. Characteristic of natural rubber latex-methyl metha-crylate copolymer in mineral lubricant base oil

    International Nuclear Information System (INIS)

    Meri Suhartini; Rahmawati

    2010-01-01

    Natural rubber latex-methyl methacrylate copolymer was diluted in xylene, then diluted in four types of lubricant base oil with concentrations of 0.25%, 1%, 5%, and 10%. The mixed solutions were analyzed to obtain kinematics viscosity, viscosity index, density, ash content, metal content, flash point, shear stability and total alkali number. The viscosity index of sample, increased by adding the copolymer solution. The results showed that lubricant base oil of High Viscosity index (HVI) 60 and mixed HVI 60: HVI 650 gave optimum viscosity index. The higher concentration of polymer added into base lubricant oil, the higher viscosity index obtained. The shear stability test showed that the kinematics viscosity of sample decreased 6.5% after 60 minutes of treatment test. (author)

  1. A LaTeX graphics routine for drawing Feynman diagrams

    International Nuclear Information System (INIS)

    Levine, M.J.S.

    1990-01-01

    FEYNMAN is a LaTeX macropackage which allows the user to construct a versatile range of Feynman diagrams within the text of a document. Diagrams of publication quality may be drawn with relative ease and rapidity. (orig.)

  2. Gender stereotype endorsement differentially predicts girls' and boys' trait-state discrepancy in math anxiety.

    Science.gov (United States)

    Bieg, Madeleine; Goetz, Thomas; Wolter, Ilka; Hall, Nathan C

    2015-01-01

    Mathematics is associated with anxiety for many students; an emotion linked to lower well-being and poorer learning outcomes. While findings typically show females to report higher trait math anxiety than males, no gender differences have to date been found in state (i.e., momentary) math anxiety. The present diary study aimed to replicate previous findings in investigating whether levels of academic self-concept was related to this discrepancy in trait vs. state anxiety measures. Additionally, mathematics-related gender stereotype endorsement (mathematics is a male domain) was investigated as an additional predictor of the trait-state discrepancy. The sample included 755 German 9th and 10th graders who completed self-report measures of trait math anxiety, math self-concept, and gender stereotype endorsement, in addition to state measures of anxiety after math classes by use of a standardized diary for 2-3 weeks (N within = 6207). As expected, females reported higher trait math anxiety but no gender differences were found for state math anxiety. Also in line with our assumptions, multilevel analyses showed the discrepancy between trait and state anxiety to be negatively related to students' self-concept (i.e., a lower discrepancy for students with higher self-concepts). Furthermore, gender stereotype endorsement differentially predicted the trait-state discrepancy: When controlling for self-concept in mathematics, females who endorsed the gender stereotype of math being a male domain more strongly overestimated their trait math anxiety as compared to their state anxiety whereas this effect was not significant for males. The present findings suggest that gender stereotype endorsement plays an important role in explaining gender differences in math anxiety above and beyond academic self-concept. Implications for future research and educational practice are discussed.

  3. Gender stereotype endorsement differentially predicts girls' and boys' trait-state discrepancy in math anxiety

    Directory of Open Access Journals (Sweden)

    Madeleine eBieg

    2015-09-01

    Full Text Available Mathematics is associated with anxiety for many students; an emotion linked to lower well-being and poorer learning outcomes. While findings typically show females to report higher trait math anxiety than males, no gender differences have to date been found in state (i.e., momentary math anxiety. The present diary study aimed to replicate previous findings in investigating whether levels of academic self-concept was related to this discrepancy in trait versus state anxiety measures. Additionally, mathematics-related gender stereotype endorsement (mathematics is a male domain was investigated as an additional predictor of the trait-state discrepancy. The sample included 755 German 9th and 10th graders who completed self-report measures of trait math anxiety, math self-concept, and gender stereotype endorsement, in addition to state measures of anxiety after math classes by use of a standardized diary for 2-3 weeks (Nwithin = 6207. As expected, females reported higher trait math anxiety but no gender differences were found for state math anxiety. Also in line with our assumptions, multilevel analyses showed the discrepancy between trait and state anxiety to be negatively related to students’ self-concept (i.e., a lower discrepancy for students with higher self-concepts. Furthermore, gender stereotype endorsement differentially predicted the trait-state discrepancy: When controlling for self-concept in mathematics, females who endorsed the gender stereotype of math being a male domain more strongly overestimated their trait math anxiety as compared to their state anxiety whereas this effect was not significant for males. The present findings suggest that gender stereotype endorsement plays an important role in explaining gender differences in math anxiety above and beyond academic self-concept. Implications for future research and educational practice are discussed.

  4. Math Tracks: What Pace in Math Is Best for the Middle School Child?

    Science.gov (United States)

    Morrison, Michelle

    2011-01-01

    Mathematics is a critical part of academic preparation of the middle school child, or, as Dr. Maria Montessori would refer to them, children in the third plane of development. Montessori educators are sincere in their endeavors not only to prepare young students for further studies of math and the application of math in their world and careers,…

  5. Literacy Specialists in Math Class! Closing the Achievement Gap on State Math Assessments

    Science.gov (United States)

    DiGisi, Lori L.; Fleming, Dianne

    2005-01-01

    Sixth and eighth grade students who are English language learners must be able to read and interpret 39 math word problems in order to successfully calculate the answers on the Massachusetts state math assessment (MCAS). The first year that MCAS was administered, many ELL students read the questions, found them confusing, and left them blank,…

  6. Radiation-induced grafting polymerization of MMA onto polybutadiene rubber latex

    International Nuclear Information System (INIS)

    Peng Jing; Wang Maolin; Qiao Jinliang; Wei Genshuan

    2005-01-01

    The grafting of methyl methacrylate (MMA) onto polybutadiene rubber latex by the direct radiation method was carried out. The effects of monomer concentration, absorbed dose and dose rate of gamma rays on the grafting yield were investigated. The graft copolymers were characterized by transmission electron microscopy (TEM), FTIR spectroscopy, and differential scanning calorimetry. TEM photographs revealed that the core-shell structures of latex particles are formed at low MMA content, and with the increasing of MMA content, the semi-IPN-like structure with core-shell could be developed due to the high gel fraction of polybutadiene (PBD) seed particles. In addition, infrared analysis confirmed that MMA could be grafted onto PBD molecular chains effectively under appropriate irradiation conditions. The interfacial adhesion between PBD rubber (core) and PMMA (shell) phases could be enhanced with the increase of MMA concentration

  7. Oil-Acrylic hybrid latexes as binders for waterborne coatings

    NARCIS (Netherlands)

    Hamersveld, E.M.S.; Es, van J.J.G.S.; 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

  8. 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

  9. Latex allergy in an infant with acquired hydrocephalus | Ehiozw ...

    African Journals Online (AJOL)

    We report the case of a 3 month old male infant with acquired hydrocephalus undergoing ventriculo-peritoneal shunt insertion who developed wheals and suffered a respiratory arrest following contact with latex gloves. The need for anaesthetists to effectively diagnose and properly manage this rare clinical entity is ...

  10. Math at home adds up to achievement in school.

    Science.gov (United States)

    Berkowitz, Talia; Schaeffer, Marjorie W; Maloney, Erin A; Peterson, Lori; Gregor, Courtney; Levine, Susan C; Beilock, Sian L

    2015-10-09

    With a randomized field experiment of 587 first-graders, we tested an educational intervention designed to promote interactions between children and parents relating to math. We predicted that increasing math activities at home would increase children's math achievement at school. We tested this prediction by having children engage in math story time with their parents. The intervention, short numerical story problems delivered through an iPad app, significantly increased children's math achievement across the school year compared to a reading (control) group, especially for children whose parents are habitually anxious about math. Brief, high-quality parent-child interactions about math at home help break the intergenerational cycle of low math achievement. Copyright © 2015, American Association for the Advancement of Science.

  11. Math practice and its influence on math skills and executive functions in adolescents with mild to borderline intellectual disability

    NARCIS (Netherlands)

    Jansen, B.R.J.; Lange, E.; van der Molen, M.J.

    2013-01-01

    Adolescents with mild to borderline intellectual disability (MBID) often complete schooling without mastering basic math skills, even though basic math is essential for math-related challenges in everyday life. Limited attention to cognitive skills and low executive functioning (EF) may cause this

  12. Surfactant and counter-ion distribution in styrene-butyl acrylate-acrylic acid dry latex submonolayers

    Directory of Open Access Journals (Sweden)

    Keslarek Amauri José

    2004-01-01

    Full Text Available Styrene-butyl acrylate-acrylic acid latex submonolayers prepared using a non-reactive phosphate surfactant together with a reactive sulfonate surfactant were examined in a transmission microscope using electron energy loss spectroscopy imaging (ESI-TEM. Phosphorus is nearly absent from the particles core but it is detected in a thick shell and in unusual, strongly scattering structures with a low carbon content, and largely made out of inorganic phosphate. P is also dispersed outside the particles, while S is uniformly distributed within then. The Na and N elemental maps show that the respective monovalent ions (Na+ and NH4+ have different distributions, in the latex: Na signal within the particles is stronger than in the background, while N is accumulated at the particle borders. The distributions of surfactant and counter-ions are thus different from some current assumptions, but they support recent results on the distribution of ionic constituents in latex films, by scanning electric potential microscopy.

  13. Worrying Thoughts Limit Working Memory Capacity in Math Anxiety.

    Directory of Open Access Journals (Sweden)

    Zhan Shi

    Full Text Available Sixty-one high-math-anxious persons and sixty-one low-math-anxious persons completed a modified working memory capacity task, designed to measure working memory capacity under a dysfunctional math-related context and working memory capacity under a valence-neutral context. Participants were required to perform simple tasks with emotionally benign material (i.e., lists of letters over short intervals while simultaneously reading and making judgments about sentences describing dysfunctional math-related thoughts or sentences describing emotionally-neutral facts about the world. Working memory capacity for letters under the dysfunctional math-related context, relative to working memory capacity performance under the valence-neutral context, was poorer overall in the high-math-anxious group compared with the low-math-anxious group. The findings show a particular difficulty employing working memory in math-related contexts in high-math-anxious participants. Theories that can provide reasonable interpretations for these findings and interventions that can reduce anxiety-induced worrying intrusive thoughts or improve working memory capacity for math anxiety are discussed.

  14. Extraction and comparison of proteins from natural rubber latex by conventional and ionizing radiation methods

    International Nuclear Information System (INIS)

    Rogero, Sizue O.; Spencer, Patrick J.; Campos, Vania E.; Lusvarghi, Fabio M.; Higa, Olga Z.

    1997-01-01

    Several proteins in natural rubber latex (NRL) have been assigned to be significant allergens. It is known that proteins submitted to ionizing radiation suffer denaturation and immunochemical modification resulting in low antigenic reactivity. The aim of this study was to extract and compare water extractable proteins from NRL films vulcanized by conventional and by ionizing radiation methods. SDS-polyacrylamide gel electrophoresis (SDS--PAGE) and high pressure liquid chromatography (HPLC) showed a diffuse protein band of about 14 KDa, which we believe is rubber elongation factor (REF), in both eluates, but smaller in latex film vulcanized by ionizing radiation. REF has been suggested to be a major latex allergen. These data suggest that ionizing radiation vulcanization could be an useful method for the production of NRL goods with low antigenicity. (author). 8 refs., 2 figs., 1 tab

  15. The Sum of All Fears: The Effects of Math Anxiety on Math Achievement in Fifth Grade Students and the Implications for School Counselors

    Science.gov (United States)

    Ruff, Sarah E.; Boes, Susan R.

    2014-01-01

    Low math achievement is a recurring weakness in many students. Math anxiety is a persistent and significant theme to math avoidance and low achievement. Causes for math anxiety include social, cognitive, and academic factors. Interventions to reduce math anxiety are limited as they exclude the expert skills of professional school counselors to…

  16. The polymerization of aniline in polystyrene latex particles

    Czech Academy of Sciences Publication Activity Database

    Blinova, Natalia V.; Reynaud, S.; Roby, F.; Trchová, Miroslava; Stejskal, Jaroslav

    2010-01-01

    Roč. 160, 15/16 (2010), s. 1598-1602 ISSN 0379-6779 R&D Projects: GA AV ČR IAA400500905; GA ČR GA203/08/0686; GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * polystyrene latex * polyaniline-polystyrene composite Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.871, year: 2010

  17. 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.

  18. How preschool executive functioning predicts several aspects of math achievement in Grades 1 and 3: A longitudinal study.

    Science.gov (United States)

    Viterbori, Paola; Usai, M Carmen; Traverso, Laura; De Franchis, Valentina

    2015-12-01

    This longitudinal study analyzes whether selected components of executive function (EF) measured during the preschool period predict several indices of math achievement in primary school. Six EF measures were assessed in a sample of 5-year-old children (N = 175). The math achievement of the same children was then tested in Grades 1 and 3 using both a composite math score and three single indices of written calculation, arithmetical facts, and problem solving. Using previous results obtained from the same sample of children, a confirmatory factor analysis examining the latent EF structure in kindergarten indicated that a two-factor model provided the best fit for the data. In this model, inhibition and working memory (WM)-flexibility were separate dimensions. A full structural equation model was then used to test the hypothesis that math achievement (the composite math score and single math scores) in Grades 1 and 3 could be explained by the two EF components comprising the kindergarten model. The results indicate that the WM-flexibility component measured during the preschool period substantially predicts mathematical achievement, especially in Grade 3. The math composite scores were predicted by the WM-flexibility factor at both grade levels. In Grade 3, both problem solving and arithmetical facts were predicted by the WM-flexibility component. The results empirically support interventions that target EF as an important component of early childhood mathematics education. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Students as Math Level Designers

    DEFF Research Database (Denmark)

    Jensen, Erik Ottar; Hanghøj, Thorkild; Schoenau-Fog, Henrik

    The short paper presents preliminary findings from a pilot study on how students become motivated through design of learning games in math. The research is carried out in a Danish public school with two classes of 5th graders (N = 42 students). Over the course of two weeks, the students work...... with a design template for a runner game in the Unity 3D game design engine. The students are introduced to the concept of “flow” (Csikszentmihalyi, 1991) as a game design principle and are asked to design levels for a math runner game, which are both engaging as well as a meaningful way of learning math....... In this way, the students are positioned as “math level designers”, which means that they both have to redesign the difficulty of the runner game as well as the difficulty of the mathematical questions and possible answers....

  20. Math you can really use--every day

    CERN Document Server

    Herzog, David Alan

    2007-01-01

    Math You Can Really Use--Every Day skips mind-numbing theory and tiresome drills and gets right down to basic math that helps you do real-world stuff like figuring how much to tip, getting the best deals shopping, computing your gas mileage, and more. This is not your typical, dry math textbook. With a comfortable, easygoing approach, it: Covers math you''ll need for balancing your checkbook, choosing or managing credit cards, comparing options for mortgages, insurance, and investments, and moreIncludes the basics on fractions, decimals, percentages, measurements, and geometric mathClues you in on simple shortcutsIncludes examples plus pop quizzes with answers to help you solidify your understanding Features tear-out guides you can take with you for tipping and converting measurements Want to know how much 20% off is in dollars and cents? Want to figure out how much gas is going to cost for your road trip? This is the math book you''ll really use!

  1. Identifying Maths Anxiety in Student Nurses and Focusing Remedial Work

    Science.gov (United States)

    Bull, Heather

    2009-01-01

    Maths anxiety interferes with maths cognition and thereby increases the risk of maths errors. To initiate strategies for preventing anxiety-related errors progressing into nursing practice, this study explored the hypothesis that student nurses experience high maths anxiety in association with poor maths performance, and that high maths anxiety is…

  2. Type I allergy to natural rubber latex and type IV allergy to rubber chemicals in health care workers with glove-related skin symptoms.

    Science.gov (United States)

    Nettis, E; Assennato, G; Ferrannini, A; Tursi, A

    2002-03-01

    It has been established that there are type I and type IV allergens in latex gloves. The purpose of the study was to establish the prevalence of rubber glove-induced skin symptoms among health care workers in one Italian hospital. Health care workers (n = 1584) were evaluated using a written questionnaire and 295 respondents with glove-induced skin symptoms were tested. We performed: skin prick test with latex glove extract and commercial latex, and environmental and food allergens; glove use test; patch tests with a rubber additive series; and RASTs. Hospital employees who used or had used latex gloves at work were 1294. Three hundred and sixteen (24.4%) reported glove-induced symptoms, namely, cutaneous symptoms in all the cases and non-cutaneous symptoms in 105 subjects (8.1%). Twenty-seven of the 295 symptomatic employees tested (9.1%) were latex sensitive. Thirty-one patients (10.5%) exhibited positive patch test to rubber-related allergens. The most positive readings were obtained from the Thiuram mix and the Carba mix, with 12 and 9 positivities, respectively. The risk factors for latex skin sensitization were: a previous history of atopy and asthma; history of surgery; pre-existing hand dermatitis; work-related symptoms; and positive skin tests to common inhalant and certain foods (P skin complaints of latex gloves are related to skin irritation rather than to allergy. The immediate allergy to latex and the delayed allergy to rubber chemicals suggest that all the health care workers with glove-related dermatitis should undergo both skin prick test and glove use test to detect type I hypersensitivity to latex, and patch test to detect type IV hypersensitivity to rubber chemicals.

  3. The Effects of the Elevate Math Summer Program on Math Achievement and Algebra Readiness

    Science.gov (United States)

    Snipes, Jason; Huang, Chun-Wei; Jaquet, Karina; Finkelstein, Neal

    2016-01-01

    To raise math success rates in middle school, many schools and districts have implemented summer math programs designed to improve student preparation for algebra content in grade 8. However, little is known about the effectiveness of these programs. While students who participate typically experience learning gains, there is little rigorous…

  4. Math anxiety in Thai early adolescents: a cognitive-behavioral perspective.

    Science.gov (United States)

    Wangsiriwech, Tawatchai; Pisitsungkagarn, Kullaya; Jarukasemthawee, Somboon

    2017-08-29

    With its high prevalence and debilitating impact on students, math anxiety is well studied within the educational context. However, the problem has yet to be examined from the psychological perspective, which is necessary in order to produce a more comprehensive perspective and to pave the way for therapeutic intervention. The current study, therefore, was conducted to identify cognitive and behavioral factors relevant to the occurrence and maintenance of math anxiety. Data were collected from 300 grade 9 students (150 females and 150 males) from public and private schools in Bangkok, Thailand. Participants responded to the measures of math anxiety, negative math beliefs, negative math appraisals and math avoidance. Structural equation modeling was conducted. Model fit indices obtained consistently suggested the good fitness of the model to the data [e.g. χ2/df = 0.42, root mean square error of approximation (RMSEA) = 0.00]. Negative math beliefs, negative math appraisals and math avoidance had a significant direct effect on math anxiety. Additionally, the indirect effect of negative math appraisal was observed between negative math beliefs and math anxiety. In summary, the proposed model accounted for 84.5% of the variance in the anxiety. The findings are discussed with particular focus on implications for therapeutic intervention for math anxiety.

  5. Avoidance temperament and social-evaluative threat in college students' math performance: a mediation model of math and test anxiety.

    Science.gov (United States)

    Liew, Jeffrey; Lench, Heather C; Kao, Grace; Yeh, Yu-Chen; Kwok, Oi-man

    2014-01-01

    Standardized testing has become a common form of student evaluation with high stakes, and limited research exists on understanding the roles of students' personality traits and social-evaluative threat on their academic performance. This study examined the roles of avoidance temperament (i.e., fear and behavioral inhibition) and evaluative threat (i.e., fear of failure and being viewed as unintelligent) in standardized math test and course grades in college students. Undergraduate students (N=184) from a large public university were assessed on temperamental fear and behavioral inhibition. They were then given 15 minutes to complete a standardized math test. After the test, students provided data on evaluative threat and their math performance (scores on standardized college entrance exam and average grades in college math courses). Results indicate that avoidance temperament was linked to social-evaluative threat and low standardized math test scores. Furthermore, evaluative threat mediated the influence of avoidance temperament on both types of math performance. Results have educational and clinical implications, particularly for students at risk for test anxiety and underperformance. Interventions targeting emotion regulation and stress management skills may help individuals reduce their math and test anxieties.

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

    Science.gov (United States)

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

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

  7. Can Low-Cost Online Summer Math Programs Improve Student Preparation for College-Level Math? Evidence from Randomized Experiments at Three Universities

    Science.gov (United States)

    Chingos, Matthew M.; Griffiths, Rebecca J.; Mulhern, Christine

    2017-01-01

    Every year many students enter college without the math preparation needed to succeed in their desired programs of study. Many of these students struggle to catch up, especially those who are required to take remedial math courses before entering college-level math. Increasing the number of students who begin at the appropriate level of math has…

  8. Evaluation of the MIND Research Institute's Spatial-Temporal Math (ST Math) Program in California

    Science.gov (United States)

    Wendt, Staci; Rice, John; Nakamoto, Jonathan

    2014-01-01

    The MIND Research Institute contracted with the Evaluation Research Program at WestEd to conduct an independent assessment of mathematics outcomes in elementary school grades across California that were provided with the ST Math program. Spatial-Temporal (ST) Math is a game-based instructional software designed to boost K-5 and secondary-level…

  9. Math anxiety differentially affects WAIS-IV arithmetic performance in undergraduates.

    Science.gov (United States)

    Buelow, Melissa T; Frakey, Laura L

    2013-06-01

    Previous research has shown that math anxiety can influence the math performance level; however, to date, it is unknown whether math anxiety influences performance on working memory tasks during neuropsychological evaluation. In the present study, 172 undergraduate students completed measures of math achievement (the Math Computation subtest from the Wide Range Achievement Test-IV), math anxiety (the Math Anxiety Rating Scale-Revised), general test anxiety (from the Adult Manifest Anxiety Scale-College version), and the three Working Memory Index tasks from the Wechsler Adult Intelligence Scale-IV Edition (WAIS-IV; Digit Span [DS], Arithmetic, Letter-Number Sequencing [LNS]). Results indicated that math anxiety predicted performance on Arithmetic, but not DS or LNS, above and beyond the effects of gender, general test anxiety, and math performance level. Our findings suggest that math anxiety can negatively influence WAIS-IV working memory subtest scores. Implications for clinical practice include the utilization of LNS in individuals expressing high math anxiety.

  10. Antimicrobial activity of a 48-kDa protease (AMP48) from Artocarpus heterophyllus latex.

    Science.gov (United States)

    Siritapetawee, J; Thammasirirak, S; Samosornsuk, W

    2012-01-01

    Artocarpus heterophyllus (jackfruit) is a latex producing plant. Plant latex is produced from secretory cells and contains many intergradients. It also has been used in folk medicine. This study aimed to purify and characterize the biological activities of a protease from jackfruit latex. A protease was isolated and purified from crude latex of a jackfruit tree by acid precipitation and ion exchange chromatography. The proteolytic activities of protein were tested using gelatin- and casein-zymography. The molecular weight and isoelectric point (pl) of protein were analysed by SDS/12.5% PAGE and 2D-PAGE, respectively. Antimicrobial activity of protein was analysed by broth microdilution method. In addition, the antibacterial activity of protein against Pseudomonas aeruginosa ATCC 27853 was observed and measured using atomic force microscopy (AFM) technique. The purified protein contained protease activity by digesting gelatin- and casein-substrates. The protease was designated as antimicrobial protease-48 kDa or AMP48 due to its molecular mass on SDS-PAGE was approximately 48 kDa. The isoelectric point (pl) of AMP48 was approximately 4.2. In addition, AMP48 contained antimicrobial activities by it could inhibit the growths of Pseudomonas aeruginosa ATCC 27853 and clinical isolated Candida albicans at minimum inhibitory concentration (MIC) 2.2 mg/ml and Minimum microbicidal concentration (MMC) 8.8 mg/ml. AFM image also supported the antimicrobial activities of AMP48 by the treated bacterial morphology and size were altered from normal.

  11. Trialed production of low protein irradiated natural rubber latex in factory scale by gamma irradiation technique

    International Nuclear Information System (INIS)

    Utama, Marga; Herwinarni, S.; Halik, H.M.; Siswanto; Suharyanto; Syamsu, Y.; Handoko, B.

    2006-01-01

    Four tons fresh field natural rubber latex (FNRL) with total solid content 30% were added with 2 phr (part hundred ratio of rubber) normal butyl acrylate (nBA) then irradiated by gamma rays at 25 kGy. The irradiated FNRL was centrifuged, then the properties of irradiated centrifuged natural rubber latex (INRL) and its film were measured before and after storage for 5 months. It is found that the INRL is stable latex during storage in 5 months, with lowest protein, and free nitrosamine content. The tensile strength of INRL film was 24-27 MPa, and modulus 600% was 1,5-2,0 MPa, elongation at break was 900%, and hardness was 27-29 Shore A, while the extractable protein content less than 100 μg/g. (author)

  12. Morphologic evaluation of the use of a latex prosthesis in videolaparoscopic inguinoplasty: an experimental study in dogs Avaliação morfológica da utilização de prótese de latex na inguinoplastia videolaparoscópica: estudo experimental em cães

    Directory of Open Access Journals (Sweden)

    Luiz Henrique de Sousa

    2011-01-01

    Full Text Available PURPOSE: To evaluate the morphological aspects of the behavior of 4 types of latex biomembranes implanted in preperitoneal videolaparoscopic inguinoplasty. METHODS: Sixteen inguinoplasties were performed in 12 dogs: group 1 received an impermeable latex biomembrane in the right inguinal region and a prolene prosthesis, as control, in the contralateral inguinal region; groups 2, 3 and 4 received latex biomembranes respectively containing impermeable polyamide, 1-mm thick porous polyamide and 0.5-mm thick porous polyamide. Macro- and microscopic evaluations of the inguinal region and of the removed implants were made on the 7th, 14th, 21st and 28th days in group 1 and on the 28th postoperative day in the other groups. RESULTS: We observed absence of hematoma, seroma and infection; presence of tortuosities; induction of vascular neoformation, inflammatory reaction and collagen deposition, and full encystment of the latex biomembranes, except that with fine porous polyamide, which was partially incorporated, with the formation of microcysts. No latex biomembrane induced fibrosis as observed in the prolene control group. CONCLUSIONS: The biomembranes maintain induction of the healing process without fibrosis, are fully encysted and, except for the one with fine porous polyamide, are not incorporated into adjacent tissues. The latex biomembrane, with or without polyamide, is not recommended as a separate material for preperitoneal inguinoplasty.OBJETIVO: Avaliar aspectos morfológicos do comportamento de 4 tipos de biomembranas de latex, colocadas pré-peritonealmente em cães, por inguinoplastia videolaparoscópica. MÉTODOS: Dezesseis inguinoplastias em 12 cães: grupo 1, com biomembrana de latex impermeável inguinal direita em quatro cães e prótese de prolene, como controle, contra-lateral; grupos 2, 3 e 4, com biomembrana de latex respectivamente de poliamida impermeável, poliamida porosa com 1mm de espessura e poliamida porosa com 0,5mm de

  13. 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.

  14. Saxon Math. What Works Clearinghouse Intervention Report

    Science.gov (United States)

    What Works Clearinghouse, 2017

    2017-01-01

    "Saxon Math" is a curriculum for students in grades K-12. The amount of new math content students receive each day is limited and students practice concepts every day. New concepts are developed, reviewed, and practiced cumulatively rather than in discrete chapters or units. This review focuses on studies of "Saxon Math"'s…

  15. Investigating Validity of Math 105 as Prerequisite to Math 201 among Undergraduate Students, Nigeria

    Science.gov (United States)

    Zakariya, Yusuf F.

    2016-01-01

    In this study, the author examined the validity of MATH 105 as a prerequisite to MATH 201. The data for this study was extracted directly from the examination results logic of the university. Descriptive statistics in form of correlations and linear regressions were used to analyze the obtained data. Three research questions were formulated and…

  16. Math Education at a Crossroads

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    With an enrollment of 550 students once a year the first year course Math1 at the Technical University of Denmark is one of the largest courses at university level in Denmark. Since its re-formation 6 years ago a number of interesting valuable assets concerning undergraduate math education...

  17. From Mxit to Dr Math

    CSIR Research Space (South Africa)

    Botha, Adèle

    2013-02-01

    Full Text Available In 2007, Laurie Butgereit, a researcher at the CSIR Meraka Institute, started to use Mxit as a communication channel to tutor her son in mathematics. Her son and a number of his friends logged in, and Dr Math was born. At the inception of Dr Math...

  18. Math Branding in a Community College Library

    Science.gov (United States)

    Brantz, Malcolm; Sadowski, Edward B.

    2010-01-01

    As a strategy to promote the Arapahoe Community College Library's collections and services, the Library undertook to brand itself as a math resource center. In promoting one area of expertise, math was selected to help address the problem of a large portion of high school graduates' inability to work at college-level math. A "Math…

  19. Polybutadiene latex particle size distribution analysis utilizing a disk centrifuge

    NARCIS (Netherlands)

    Verdurmen, E.M.F.J.; Albers, J.G.; German, A.L.

    1994-01-01

    Polybutadiene (I) latexes prepd. by emulsifier-free emulsion polymn. and having particle diam. 50-300 nm for both unimodal and bimodal particles size distributions were analyzed by the line-start (LIST) method in a Brookhaven disk centrifuge photosedimentometer. A special spin fluid was designed to

  20. 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.

  1. Firefighter Math - a web-based learning tool

    Science.gov (United States)

    Dan Jimenez

    2010-01-01

    Firefighter Math is a web based interactive resource that was developed to help prepare wildland fire personnel for math based training courses. The website can also be used as a refresher for fire calculations including slope, flame length, relative humidity, flow rates, unit conversion, etc. The website is designed to start with basic math refresher skills and...

  2. Clonal stability of latex yield in eleven clones of Hevea brasiliensis Muell. Arg.

    Directory of Open Access Journals (Sweden)

    K.O. Omokhafe

    2003-01-01

    Full Text Available Eleven Hevea brasiliensis clones were evaluated for clonal stability of latex yield. A randomized complete block design was used with four replicates, two locations, seven years and three periods per year. Stability analysis was based on clone x year and clone x year x location interactions. Five stability parameters viz environmental variance, shukla's stability variance, regression of clonal latex yield on environmental index, variance due to regression and variance due to deviation from regression were applied. There was significant clone x environment effect at the two levels of interaction. Among the eleven clones, C 162 was outstanding for clonal stability and it can serve as donor parent for stability alleles. Three clones (C 76, C 150 and C 154 were also stable. The four stable clones (C 76, C 150, C 154 and C 162 are suitable for broad-spectrum recommendation for latex yield. Five clones (C 83, C 143, C 163, C 202 and RRIM 600 will require environment-specific recommendation because of their unstable phenotype. The stability feature of two clones (C 145 and C 159 was not clear and this will be investigated in subsequent studies.

  3. Safety Evaluation Test on Human for Radiation Pre vulcanised Natural Rubber Latex (RVNRL)

    International Nuclear Information System (INIS)

    Pairu Ibrahim; Wan Manshol Wan Zain; Chai, Chee Keong; Sofian Ibrahim; Saadiah Sulaiman; Sharifah Ismail

    2010-01-01

    This paper discussed about clinical test conducted to determine safety evaluations on human for latex examination gloves and latex films made from Radiation Vulcanized Natural Rubber Latex (RVNRL). Two types of test were being adopted which are i) Modified Draize-95 test and ii) Patch Test on Sensitized Individuals. Modified Draize-95 test was conducted on 200 non-sensitized human subjects and Patch Test on Sensitized Individuals was conducted on 25 individuals who are allergic to the defined major chemical sensitizer presents in natural rubber product. It was found that Modified Draize-95 test has prove that there is no clinical evidence on the presence of residual chemical additives at the level that may induce Type IV allergy in the un sensitized general user population in the RVNRL gloves. Meanwhile Patch Test on Sensitized Individuals has proved that the patch test conducted using the test article on 25 individuals who are allergic to the defined major chemical sensitizers present in natural rubber products, thiuram, carbamates or thiazoles produced a negative response, meeting the pre requirement for the claim of reduced reaction-inducing potential. (author)

  4. Immunodiagnosis of paracoccidioidomycosis due to Paracoccidioides brasiliensis using a latex test: detection of specific antibody anti-gp43 and specific antigen gp43.

    Directory of Open Access Journals (Sweden)

    Priscila Oliveira Dos Santos

    2015-02-01

    Full Text Available Paracoccidioidomycosis (PCM is a life-threatening systemic disease and is a neglected public health problem in many endemic regions of Latin America. Though several diagnostic methods are available, almost all of them present with some limitations.A latex immunoassay using sensitized latex particles (SLPs with gp43 antigen, the immunodominant antigen of Paracoccidioides brasiliensis, or the monoclonal antibody mAb17c (anti-gp43 was evaluated for antibody or antigen detection in sera, cerebrospinal fluid (CSF, and bronchoalveolar lavage (BAL from patients with PCM due to P. brasiliensis. The gp43-SLPs performed optimally to detect specific antibodies with high levels of sensitivity (98.46%, 95% CI 91.7-100.0, specificity (93.94%, 95% CI 87.3-97.7, and positive (91.4% and negative (98.9% predictive values. In addition, we propose the use of mAb17c-SLPs to detect circulating gp43, which would be particularly important in patients with immune deficiencies who fail to produce normal levels of immunoglobulins, achieving good levels of sensitivity (96.92%, 95% CI 89.3-99.6, specificity (88.89%, 95% CI 81.0-94.3, and positive (85.1% and negative (97.8% predictive values. Very good agreement between latex tests and double immune diffusion was observed for gp43-SLPs (k = 0.924 and mAb17c-SLPs (k = 0.850, which reinforces the usefulness of our tests for the rapid diagnosis of PCM in less than 10 minutes. Minor cross-reactivity occurred with sera from patients with other fungal infections. We successfully detected antigens and antibodies from CSF and BAL samples. In addition, the latex test was useful for monitoring PCM patients receiving therapy.The high diagnostic accuracy, low cost, reduced assay time, and simplicity of this new latex test offer the potential to be commercialized and makes it an attractive diagnostic assay for use not only in clinics and medical mycology laboratories, but mainly in remote locations with limited laboratory infrastructure

  5. Numbers and other math ideas come alive

    CERN Document Server

    Pappas, Theoni

    2012-01-01

    Most people don't think about numbers, or take them for granted. For the average person numbers are looked upon as cold, clinical, inanimate objects. Math ideas are viewed as something to get a job done or a problem solved. Get ready for a big surprise with Numbers and Other Math Ideas Come Alive. Pappas explores mathematical ideas by looking behind the scenes of what numbers, points, lines, and other concepts are saying and thinking. In each story, properties and characteristics of math ideas are entertainingly uncovered and explained through the dialogues and actions of its math

  6. How Math Anxiety Relates to Number–Space Associations

    Science.gov (United States)

    Georges, Carrie; Hoffmann, Danielle; Schiltz, Christine

    2016-01-01

    Given the considerable prevalence of math anxiety, it is important to identify the factors contributing to it in order to improve mathematical learning. Research on math anxiety typically focusses on the effects of more complex arithmetic skills. Recent evidence, however, suggests that deficits in basic numerical processing and spatial skills also constitute potential risk factors of math anxiety. Given these observations, we determined whether math anxiety also depends on the quality of spatial-numerical associations. Behavioral evidence for a tight link between numerical and spatial representations is given by the SNARC (spatial-numerical association of response codes) effect, characterized by faster left-/right-sided responses for small/large digits respectively in binary classification tasks. We compared the strength of the SNARC effect between high and low math anxious individuals using the classical parity judgment task in addition to evaluating their spatial skills, arithmetic performance, working memory and inhibitory control. Greater math anxiety was significantly associated with stronger spatio-numerical interactions. This finding adds to the recent evidence supporting a link between math anxiety and basic numerical abilities and strengthens the idea that certain characteristics of low-level number processing such as stronger number–space associations constitute a potential risk factor of math anxiety. PMID:27683570

  7. How math anxiety relates to number-space associations

    Directory of Open Access Journals (Sweden)

    Carrie Georges

    2016-09-01

    Full Text Available Given the considerable prevalence of math anxiety, it is important to identify the factors contributing to it in order to improve mathematical learning. Research on math anxiety typically focusses on the effects of more complex arithmetic skills. Recent evidence, however, suggests that deficits in basic numerical processing and spatial skills also constitute potential risk factors of math anxiety. Given these observations, we determined whether math anxiety also depends on the quality of spatial-numerical associations. Behavioural evidence for a tight link between numerical and spatial representations is given by the SNARC (spatial-numerical association of response codes effect, characterized by faster left-/right-sided responses for small/large digits respectively in binary classification tasks. We compared the strength of the SNARC effect between high and low math anxious individuals using the classical parity judgment task in addition to evaluating their spatial skills, arithmetic performance, working memory and inhibitory control. Greater math anxiety was significantly associated with stronger spatio-numerical interactions. This finding adds to the recent evidence supporting a link between math anxiety and basic numerical abilities and strengthens the idea that certain characteristics of low-level number processing such as stronger number-space associations constitute a potential risk factor of math anxiety.

  8. How Math Anxiety Relates to Number-Space Associations.

    Science.gov (United States)

    Georges, Carrie; Hoffmann, Danielle; Schiltz, Christine

    2016-01-01

    Given the considerable prevalence of math anxiety, it is important to identify the factors contributing to it in order to improve mathematical learning. Research on math anxiety typically focusses on the effects of more complex arithmetic skills. Recent evidence, however, suggests that deficits in basic numerical processing and spatial skills also constitute potential risk factors of math anxiety. Given these observations, we determined whether math anxiety also depends on the quality of spatial-numerical associations. Behavioral evidence for a tight link between numerical and spatial representations is given by the SNARC (spatial-numerical association of response codes) effect, characterized by faster left-/right-sided responses for small/large digits respectively in binary classification tasks. We compared the strength of the SNARC effect between high and low math anxious individuals using the classical parity judgment task in addition to evaluating their spatial skills, arithmetic performance, working memory and inhibitory control. Greater math anxiety was significantly associated with stronger spatio-numerical interactions. This finding adds to the recent evidence supporting a link between math anxiety and basic numerical abilities and strengthens the idea that certain characteristics of low-level number processing such as stronger number-space associations constitute a potential risk factor of math anxiety.

  9. 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.

  10. Latex allergy: assessment of knowledge, appropriate use of gloves and prevention practice among hospital healthcare workers.

    Science.gov (United States)

    Al-Niaimi, F; Chiang, Y Z; Chiang, Y N; Williams, J

    2013-01-01

    Healthcare workers and patients are often exposed to natural rubber latex (NRL) through contact with gloves and various healthcare products, which can potentially cause allergic reactions, with varying degrees of severity. In 2008, the Royal College of Physicians published their first evidence-based guidance on occupational health interventions for latex allergy, which emphasized the importance of healthcare workers having knowledge of latex allergy. This study aimed to survey the knowledge of healthcare workers (n = 156) about latex gloves and NRL allergy, routine prevention practice and the appropriate use of gloves in patient care. Healthcare workers in a large teaching hospital were surveyed using a standard questionnaire. We found that only 1% of healthcare workers were able to correctly match the appropriate gloves to the specifically designed procedure. More than half (n = 74.53%) were unable to recognize the presentation of type 1 allergy to NRL. Of the 156 participants, 131 (84%) considered that they would benefit from training about NRL allergy and the use of different types of gloves in clinical care. This survey indicates the importance of education regarding appropriate use of gloves and prevention of NRL allergy among healthcare workers, and dermatologists should play an important role in facilitating this. © The Author(s). CED © 2012 British Association of Dermatologists.

  11. Order of Administration of Math and Verbal Tests: An Ecological Intervention to Reduce Stereotype Threat on Girls' Math Performance

    Science.gov (United States)

    Smeding, Annique; Dumas, Florence; Loose, Florence; Régner, Isabelle

    2013-01-01

    In 2 field experiments, we relied on the very features of real testing situations--where both math and verbal tests are administered--to examine whether order of test administration can, by itself, create vs. alleviate stereotype threat (ST) effects on girls' math performance. We predicted that taking the math test before the verbal test would be…

  12. "Math Anxiety" Explored in Studies

    Science.gov (United States)

    Sparks, Sarah D.

    2011-01-01

    Math problems make more than a few students--and even teachers--sweat, but new brain research is providing insights into the earliest causes of the anxiety so often associated with mathematics. Experts argue that "math anxiety" can bring about widespread, intergenerational discomfort with the subject, which could lead to anything from fewer…

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

    Science.gov (United States)

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

    2014-01-01

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

  14. Do Growth Mindsets in Math Benefit Females? Identifying Pathways between Gender, Mindset, and Motivation.

    Science.gov (United States)

    Degol, Jessica L; Wang, Ming-Te; Zhang, Ya; Allerton, Julie

    2018-05-01

    Despite efforts to increase female representation in science, technology, engineering, and mathematics (STEM), females continue to be less motivated to pursue STEM careers than males. A short-term longitudinal study used a sample of 1449 high school students (grades 9-12; 49% females) to examine pathways from gender and mindset onto STEM outcomes via motivational beliefs (i.e., expectancy beliefs, task value, and cost). Mindset, motivational beliefs, and STEM career aspirations were assessed between the fall and winter months of the 2014-2015 school year and math grades were obtained at the conclusion of the same year. Student growth mindset beliefs predicted higher task values in math. Task values also mediated the pathway from a growth mindset to higher STEM career aspirations. Expectancy beliefs mediated the pathway between gender and math achievement. This mediated pathway was stronger for females than for males, such that females had higher math achievement than males when they endorsed a growth mindset. Findings suggest possible avenues for improving female's interest in STEM.

  15. Diagnosis of Trichomonous vaginalis by microscopy, latex agglutination, diamond's media, and PCR in symptomatic women, Khartoum, Sudan.

    Science.gov (United States)

    Saleh, Amir M; Abdalla, Hamid S; Satti, Abdelsalam B; Babiker, Suad M; Gasim, Gasim I; Adam, Ishag

    2014-03-06

    Trichomoniasis is the most common sexually transmitted disease. However, limited data are available on an effective technique for the diagnosis of Trichomonas vaginalis. A cross-sectional study was conducted to evaluate the accuracy of wet mount microscopy, latex agglutination, Diamond's media, and polymerase chain reaction (PCR) for detection of T. vaginalis among symptomatic women who attended the gynecological clinic at Khartoum, Sudan. Of the 297 women studied, 252 (84.8%) were positive for T. vaginalis by wet mount microscopy, 257 (86.5%) by latex agglutination, 253 (85.2%) by Diamond's media, and 253 (85.2%) by PCR. The sensitivity and specificity of wet mount microscopy were 99.2% and 97.7%, respectively, compared with PCR. The sensitivity and specificity of latex agglutination and Diamond's media were 99.6% and 88.6%, and 100.0% and 86.4%, respectively, compared with PCR. In this study, wet mount microscopy, latex agglutination, and Diamond's media were found to be highly sensitive and specific. However, the availability and cost effectiveness might limit the use of Diamond's media and PCR in routine practice. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7859723851211496.

  16. A Motivational Technique for Business Math

    Science.gov (United States)

    Voelker, Pamela

    1977-01-01

    The author suggests the use of simulation and role playing as a method of motivating students in business math. Examples of career-oriented business math simulation games are counting change, banking, payrolls, selling, and shopping. (MF)

  17. Preparation and Characterization of Conducting Polymer Latices by Chemical Polymerization of Aniline or Anisidine in Presence of Latex: Study of Their Electroactivity and Anti-Corrosion Properties

    Directory of Open Access Journals (Sweden)

    Bakhshali Massoumi

    2013-06-01

    Full Text Available Poly (vinylacetate-co-butylmethacrylate was prepared in presence of potassium persulphate as an oxidizing agent in aqueous solution of dodecylbenzene sulfonate sodium as an emulsifying agent. Then, aniline was polymerized by chemical oxidation method at three different concentrations of aniline monomer (0.1, 0.2 and 0.3 M in toluene in presence of poly(vinylacetate-co-butylmethacrylate in order to obtain polyaniline/poly(vinylacetate-co-butylmethacrylate. To prepare conducting-latex of polyanisidine/poly(vinylacetate-co-butylmethacrylate the same method was employed as above for aniline monomer in obtaining conducting polyaniline/poly(vinylacetate-co-butylmethacrylate latex. In addition, the purification of conducting-latex polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate was conducted and preparation of tin layer films of conducting-latex polymers was carried out by casting method on glassy lames. The electroactivity properties of the prepared latex-polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate were investigated by cyclic voltammetery (CV. The voltamogrames showed that the latex films were electroactive. Because of conductivity and electroactivity, the obtained films may find applications in anti-corrosion coatings. The anti-corrosion properties of conducting-latex polymers were studied on aluminum surface by impedance technique. The structure of the prepared conducting-latex polymers was confirmed by Fourier transform infrared (FTIR. Finally, the electrical conductivity of synthesized conducting-latex polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate was measured by four probe technique.

  18. What Math Teachers Need Most

    Science.gov (United States)

    Nelson, Barbara Scott; Sassi, Annette

    2007-01-01

    The combination of new instructional methods and new accountability pressures puts many in a quandary in evaluating math instruction. There is much for principals to learn about how and under what conditions new instructional methods work in math classrooms, how to support teachers as they develop new instructional skills, and how to integrate a…

  19. Math Fact Strategies Research Project

    Science.gov (United States)

    Boso, Annie

    2011-01-01

    An action research project was conducted in order to determine effective math fact strategies for first graders. The traditional way of teaching math facts included using timed tests and flashcards, with most students counting on their fingers or a number line. Six new research-based strategies were taught and analyzed to decide which methods…

  20. Latex content and biomass increase in Mycorrhizal guayule (Parthenium argentatum) under field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bloss, H.E.; Pfeiffer, C.M.

    1984-01-01

    Guayule seedlings were inoculated with two Glomus species in pasteurised soil and grown in the glasshouse without added fertilizer for 8 weeks prior to transplanting to the field. The survival rate of transplanted guayule seedlings was increased by inoculation with vesicular arbuscular mycorrhizal fungi compared wtih uninoculated controls. Inoculated guayule had greater concentrations of Ca, Fe, Mg and Mn at six months of age, and greater concentrations of Ca, Mg, and Zn at 12 months of age than did uninoculated plants. The latex content of both roots and shoots of guayule was greater in inoculated than in uninoculated guayule plants at 12 and 18 months of age. The resin content remained unchanged between treatments irrespective of sampling date.

  1. Developing Mathematical Resilience of Prospective Math Teachers

    Science.gov (United States)

    Ariyanto, L.; Herman, T.; Sumarmo, U.; Suryadi, D.

    2017-09-01

    Prospective math teachers need to develop positive adaptive attitudes toward mathematics that will enable them to continue learning despite having to deal with obstacles and difficulties. This research focuses on the resilience improvement of the prospective mathematic teachers after being treated using problem-based learning based on their basic knowledge on mathematic and their overall knowledge on math. This research used only one group for pre-test and post-test. The result of this research shows that there is improvement on prospective teachers’ resilience after they were given treatment using problem-based learning. One of the factors causing the resilience improvement of the prospective mathematic teachers is the instructions on students’ work sheet. In the instructions, stud ents were asked to write difficulties in solving math problems as well as write down the solution they take to overcome them. This research can be used as a reference for other researchers who want to do the same research related on students’ resiliency o n math and or math lecturers to improve the resilience of prospective teachers to be resilient teachers on math in the future.

  2. Does Geographic Setting Alter the Roles of Academically Supportive Factors? African American Adolescents' Friendships, Math Self-Concept, and Math Performance

    Science.gov (United States)

    Jones, Martin H.; Irvin, Matthew J.; Kibe, Grace W.

    2012-01-01

    The study is one of few to examine how living in rural, suburban, or urban settings may alter factors supporting African Americans adolescents' math performance. The study examines the relationship of math self-concept and perceptions of friends' academic behaviors to African American students' math performance. Participants (N = 1,049) are…

  3. How to Make the Most of Math Manipulatives.

    Science.gov (United States)

    Burns, Marilyn

    1996-01-01

    A discussion of how to use math manipulatives to teach elementary students focuses on essential program elements: what math manipulatives are and why they are used, common questions about math manipulatives, how one teacher introduced the geoboard into the classroom, and pattern block activities. (SM)

  4. Math Learning Begins at Home

    Science.gov (United States)

    Eason, Sarah H.; Levine, Susan C.

    2017-01-01

    Children demonstrate gaps in the math knowledge that they possess by the time they begin school, and these gaps have been found to predict long-term outcomes not only in math but also in reading. Consequently, it is important to identify what accounts for these early differences and how they can be addressed to ensure that all children enter…

  5. Basic math and pre-algebra practice problems for dummies

    CERN Document Server

    Zegarelli, Mark

    2013-01-01

    1001 Basic Math & Pre- Algebra Practice Problems For  Dummies   Practice makes perfect-and helps deepen your understanding of basic math and pre-algebra 1001 Basic Math & Pre-Algebra Practice Problems For Dummies, with free access to online practice problems, takes you beyond the instruction and guidance offered in Basic Math & Pre-Algebra For Dummies, giving you 1,001 opportunities to practice solving problems from the major topics in your math course. You begin with some basic arithmetic practice, move on to fractions, decimals, and per

  6. Math Academy: Are You Game? Explorations in Probability. Supplemental Math Materials for Grades 3-6

    Science.gov (United States)

    Rimbey, Kimberly

    2007-01-01

    Created by teachers for teachers, the Math Academy tools and activities included in this booklet were designed to create hands-on activities and a fun learning environment for the teaching of mathematics to the students. This booklet contains the themed program "Are You Game? Math Academy--Explorations in Probability," which teachers can use to…

  7. Radio-vulcanization of natural rubber in the latex phase. Study of an experimental 1 tonne per hour production; Radio-vulcanisation du caoutchouc naturel en phase latex. Etude d'une production experimentale de 1 tonne par heure

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, P; Puig, J R; Roudeix, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    After briefly reviewing the main research carried out on the radio-vulcanization of latex and elastomers, a description is given of 4 types of cell which have been used successively with a view to industrial irradiation. They have made it possible to acquire the information necessary for resolving the main problem arising during irradiation - the formation of coagulum. The first two cell are designed for irradiation by a horizontal beam ('Dynamitron'), the two others use a vertical beam ('Circe'). The study of the properties of the rubber obtained shows it to compare favorably with 'Revultex'. In the appendix are given some characteristics of natural latex and information about its processing. (authors) [French] Apres un rappel des principales etudes sur la radio-vulcanisation du latex et des elastomeres, on decrit les quatre types de cellules successivement essayes en vue de l'irradiation industrielle. Ils ont permis d'acquerir les informations necessaires a la resolution du probleme principal pose par l'irradiation, la formation de coagulum au cours de celle,-ci. Les deux premiers sont concus pour l'irradiation par un faisceau horizontal ('Dynamitron'), les derniers par un faisceau vertical ('Circe'). L'etude des proprietes du caoutchouc obtenu montre qu'il se compare favorablement au 'Revultex'. Un apercu est donne en annexe des caracteristiques du latex naturel et de sa mise en oeuvre. (auteurs)

  8. 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.

  9. 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.

  10. Synthesis and characterization of novel fluoroalkyl-terminated hyperbranched polyurethane latex

    Science.gov (United States)

    Xu, Wei; Zhao, Weijia; Hao, Lifen; Wang, Sha; Pei, Mengmeng; Wang, Xuechuan

    2018-04-01

    Waterborne polyurethane (PU) emulsions are widely used in various fields and the demand for them is ever-increasing over the years. However, the hydrophilic chain extender inevitably bonded into the PU backbone can affect the water tolerance of PU. Thus, it is of great importance to improve PU water resistance effectively. Herein, novel fluoroalkyl-terminated hyperbranched polyurethane (HBPUF) latex was accordingly synthesized by graft reaction of perfluorohexyl ethyl alcohol and hyperbranched polyurethane (HBPU), which was previously obtained from interaction between hydroxyl-terminated hyperbranched polymer and PU prepolymer manufactured via the acetone process, as well as using neutralization, adding water, and high-speed stirring operations. We characterized the resultants and investigated its surface properties by IR, NMR, TEM, XRD, TGA, DSC, FE-SEM, AFM, XPS, and contact angle measurements, etc. IR and NMR tests confirmed that the fluorinated fragments had been grafted onto the tail end of HBPU. TEM, XRD, DSC, and FE-SEM results all accounted for the fact that there were multi-crystals in PU, HBPU and HBPUF. TGA results showed that thermal stabilities of the PU, HBPU, and HBPUF latex films were enhanced in turn. XPS and AFM analyses demonstrated that the fluorine-containing segments from the HBPUF terminals were prone to migrate and enrich on the film-air surface of the HBPUF latex film, which made water contact angle and water absorption of the HBPUF film be as 113.9° and 11.1%, respectively, compared to those of the PU film (77.8° and 136.2%). This research indicates that water resistance of the PU film can be efficiently enhanced by fluorinated polyurethane with novel fluoroalkyl-terminated hyperbranched structure.

  11. Primary maths anyone can feed skittles to sharks

    CERN Document Server

    Tiley-Nunn, Nick

    2014-01-01

    Primary maths is stereotypically loved by a few hairy oddballs, tolerated by most sane primary practitioners; loathed by many. With the right approach, however; the right mindset and sense of the impossible being achievable, maths can be moulded into the diamond in the rough of the primary curriculum. Enter Nick Tiley-Nunn: Britain's most imaginative, most exciting primary maths specialist. Over years of practice he has generated ideas about the teaching of maths that are so distinct, so far out and so utterly brilliant that any primary teacher struggling to grasp the nettle of teaching long division will emerge from communing with his ideas not just with some clichéd sense that ‘maths can be fun', but that it can be brilliant, life-enhancing and truly hilarious. This book presents ideas for primary maths teaching so wildly creative and so full of the joy of life that any classroom of kids will be grateful you read it.

  12. Training the approximate number system improves math proficiency.

    Science.gov (United States)

    Park, Joonkoo; Brannon, Elizabeth M

    2013-10-01

    Humans and nonhuman animals share an approximate number system (ANS) that permits estimation and rough calculation of quantities without symbols. Recent studies show a correlation between the acuity of the ANS and performance in symbolic math throughout development and into adulthood, which suggests that the ANS may serve as a cognitive foundation for the uniquely human capacity for symbolic math. Such a proposition leads to the untested prediction that training aimed at improving ANS performance will transfer to improvement in symbolic-math ability. In the two experiments reported here, we showed that ANS training on approximate addition and subtraction of arrays of dots selectively improved symbolic addition and subtraction. This finding strongly supports the hypothesis that complex math skills are fundamentally linked to rudimentary preverbal quantitative abilities and provides the first direct evidence that the ANS and symbolic math may be causally related. It also raises the possibility that interventions aimed at the ANS could benefit children and adults who struggle with math.

  13. Direct detection of methicillin resistance in Staphylococcus aureus in blood culture broth by use of a penicillin binding protein 2a latex agglutination test.

    Science.gov (United States)

    Qian, Qinfang; Venkataraman, Lata; Kirby, James E; Gold, Howard S; Yamazumi, Toshiaki

    2010-04-01

    We studied the utility of performing a penicillin binding protein 2a latex agglutination (PBP-LA) assay directly on Bactec blood culture broth samples containing Staphylococcus aureus to rapidly detect methicillin resistance. The sensitivity, specificity, positive predictive value, and negative predictive value of this method were 94.1%, 97.5%, 98%, and 92.9%, respectively.

  14. Direct Detection of Methicillin Resistance in Staphylococcus aureus in Blood Culture Broth by Use of a Penicillin Binding Protein 2a Latex Agglutination Test▿

    OpenAIRE

    Qian, Qinfang; Venkataraman, Lata; Kirby, James E.; Gold, Howard S.; Yamazumi, Toshiaki

    2010-01-01

    We studied the utility of performing a penicillin binding protein 2a latex agglutination (PBP-LA) assay directly on Bactec blood culture broth samples containing Staphylococcus aureus to rapidly detect methicillin resistance. The sensitivity, specificity, positive predictive value, and negative predictive value of this method were 94.1%, 97.5%, 98%, and 92.9%, respectively.

  15. Specific Cognitive Predictors of Early Math Problem Solving

    Science.gov (United States)

    Decker, Scott L.; Roberts, Alycia M.

    2015-01-01

    Development of early math skill depends on a prerequisite level of cognitive development. Identification of specific cognitive skills that are important for math development may not only inform instructional approaches but also inform assessment approaches to identifying children with specific learning problems in math. This study investigated the…

  16. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    Science.gov (United States)

    Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd; Boondamnoen, O.; Tai, Mun Foong

    2015-12-01

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm-1 and 700 cm-1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (-14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability.

  17. The Aftermath of Remedial Math: Investigating the Low Rate of Certificate Completion among Remedial Math Students

    Science.gov (United States)

    Bahr, Peter Riley

    2013-01-01

    Nationally, a majority of community college students require remedial assistance with mathematics, but comparatively few students who begin the remedial math sequence ultimately complete it and achieve college-level math competency. The academic outcomes of students who begin the sequence but do not complete it are disproportionately unfavorable:…

  18. Study on grafting of monomer onto natural rubber latex by radiation technique

    International Nuclear Information System (INIS)

    Nguyen Tan Man; Le Hai; Tran Thi Tam; Le Huu Tu, Pham Thi Sam; Dao Minh Phuong; Ha Thuc Huy

    2004-01-01

    Radiation vulcanization of natural rubber latex has been extensively developed through programmers assisted by the IAEA and UNDP under RCA in Asia and Pacific Region. R-D has been done in most of the Member States with technical assistance from Japan's Takasaki Radiation Chemistry Establishment. Radiation vulcanized natural rubber latex (RVNRL) has many advantages over the conventional sulfur vulcanized latex, such as absence of nitrosamine and low cytotoxicity. Radiation crosslinking is a room temperature process, itself an important cost advantage, it is easily controlled and desired extend of crosslinking is easily achieved by controlling the dose (irradiation time). Disadvantages of RVNRL to be improved are poor physical properties of film such as low tensile strength and tear strength. The research groups of Japan, Thailand and Indonesia concentrated on the improvement of physical properties of RVNRL using radiation grafted PMMA as additive [2]. F. Sundardi and W. Sofiarti have reported that tensile strength and hardness increased by radiation grafting of styrene onto NR [5]. Ono et al have reported the grafting of MMA onto NR by gamma irradiation at a dose of 5 kGy for producing thermoplastic elastomers [4]. The objective of this project is to report the results of studies of radiation graft-copolymerization of methyl methacrylate (MMA) or styrene (St) onto natural rubber latex in order to improve their physico-mechanical properties and evaluation of grafted material using Small-Angle Neutron Scattering through FNCA Project. The grafting degree of MMA and St onto NR increased with the increase of irradiation dose and monomer concentration. The alteration of grafted products structure was determined by IR method. Tensile strength, Shore A hardness, 100% modulus of grafted products increased with the increase of monomer concentration and irradiation dose while elongation at break decreased. The grafted products were characterized by Transmission Electron

  19. Math word problems for dummies

    CERN Document Server

    Sterling, Mary Jane

    2008-01-01

    Covers percentages, probability, proportions, and moreGet a grip on all types of word problems by applying them to real lifeAre you mystified by math word problems? This easy-to-understand guide shows you how to conquer these tricky questions with a step-by-step plan for finding the right solution each and every time, no matter the kind or level of problem. From learning math lingo and performing operations to calculating formulas and writing equations, you''ll get all the skills you need to succeed!Discover how to: * Translate word problems into plain English* Brush up on basic math skills* Plug in the right operation or formula* Tackle algebraic and geometric problems* Check your answers to see if they work

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

    Directory of Open Access Journals (Sweden)

    El-Sayed Negim

    2014-01-01

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

  1. Composite poly(methyl methacrylate-methacrylic acid-2-hydroxyethyl methacrylate) latex for immunoassay. The case of plasminogen.

    Science.gov (United States)

    Miksa, B; Wilczynska, M; Cierniewski, C; Basinska, T; Slomkowski, S

    1995-01-01

    Poly(methyl methacrylate-methacrylic acid-2-hydroxyethyl methacrylate) latex (ACRYLAT) was synthesized by radical precipitation polymerization. The mass median diameter (MMD) and the geometrical standard deviation (GSD) of the ACRYLAT particles were 138 nm and 1.2, respectively. The concentration of the titrable carboxylic groups in the surface layer of latex particles was equal to 8.41 x 10(-6) mol m-2. Latex was able to bind up to 2.82 x 10(-7) mol of 1-aminopyrene per 1 m2 of the surface of the latex particles due to the ionic interactions between carboxylate anions and ammonium cations of protonated 1-aminopyrene. ACRYLAT was able to immobilize covalently human serum albumin in amounts up to 0.23 mg m-2. Aggregation of ACRYLAT with immobilized HSA, induced with specific antibodies (anti-HSA), was investigated turbidimetrically. The results indicated that in the model turbidimetric immunoassay, ACRYLAT coated with HSA can be used for the detection of anti-HSA in the goat anti-HSA serum diluted from 50 to 7000-fold. Immobilization of rabbit antibodies to plasminogen (anti-Plg) to ACRYLAT via the epsilon-aminocaproic acid linkers provided particles which were used for the development of the turbidimetric immunoassay for plasminogen. In this assay plasminogen could be detected in concentration ranging from 0.75 to 75 micrograms ml-1 in the blood plasma.

  2. Business math for dummies

    CERN Document Server

    Sterling, Mary Jane

    2008-01-01

    Now, it is easier than ever before to understand complex mathematical concepts and formulas and how they relate to real-world business situations. All you have to do it apply the handy information you will find in Business Math For Dummies. Featuring practical practice problems to help you expand your skills, this book covers topics like using percents to calculate increases and decreases, applying basic algebra to solve proportions, and working with basic statistics to analyze raw data. Find solutions for finance and payroll applications, including reading financial statements, calculating wages and commissions, and strategic salary planning. Navigate fractions, decimals, and percents in business and real estate transactions, and take fancy math skills to work. You'll be able to read graphs and tables and apply statistics and data analysis. You'll discover ways you can use math in finance and payroll investments, banking and payroll, goods and services, and business facilities and operations. You'll learn ho...

  3. A Correlation of Community College Math Readiness and Student Success

    Science.gov (United States)

    Brown, Jayna Nicole

    Although traditional college students are more prepared for college-level math based on college admissions tests, little data have been collected on nontraditional adult learners. The purpose of this study was to investigate relationships between math placement tests and community college students' success in math courses and persistence to degree or certificate completion. Guided by Tinto's theory of departure and student retention, the research questions addressed relationships and predictability of math Computer-adaptive Placement Assessment and Support System (COMPASS) test scores and students' performance in math courses, persistence in college, and degree completion. After conducting correlation and regression analyses, no significant relationships were identified between COMPASS Math test scores and students' performance (n = 234) in math courses, persistence in college, or degree completion. However, independent t test and chi-squared analyses of the achievements of college students who tested into Basic Math (n = 138) vs. Introduction to Algebra (n = 96) yielded statistically significant differences in persistence (p = .039), degree completion (p college students' math competencies and degree achievement.

  4. Finite Element Analysis of Simple Rectangular Microstrip Sensor for Determination Moisture Content of Hevea Rubber Latex

    Science.gov (United States)

    Yahaya, NZ; Ramli, MR; Razak, NNANA; Abbas, Z.

    2018-04-01

    The Finite Element Method, FEM has been successfully used to model a simple rectangular microstrip sensor to determine the moisture content of Hevea rubber latex. The FEM simulation of sensor and samples was implemented by using COMSOL Multiphysics software. The simulation includes the calculation of magnitude and phase of reflection coefficient and was compared to analytical method. The results show a good agreement in finding the magnitude and phase of reflection coefficient when compared with analytical results. Field distributions of both the unloaded sensor as well as the sensor loaded with different percentages of moisture content were visualized using FEM in conjunction with COMSOL software. The higher the amount of moisture content in the sample the more the electric loops were observed.

  5. Carnegie Math Pathways 2015-2016 Impact Report: A Five-Year Review. Carnegie Math Pathways Technical Report

    Science.gov (United States)

    Hoang, Hai; Huang, Melrose; Sulcer, Brian; Yesilyurt, Suleyman

    2017-01-01

    College math is a gateway course that has become a constraining gatekeeper for tens of thousands of students annually. Every year, over 500,000 students fail developmental mathematics, preventing them from achieving their college and career goals. The Carnegie Math Pathways initiative offers students an alternative. It comprises two Pathways…

  6. Inhibition Performance in Children with Math Disabilities

    OpenAIRE

    Winegar, Kathryn Lileth

    2013-01-01

    This study examined the inhibition deficit hypothesis in children with math disabilities (MD). Children with and without MD were compared on two inhibition tasks that included the random generation of numbers and letters. The results addressed three hypotheses. Weak support was found for the first hypothesis which stated difficulties related to inhibition are significantly related to math performance. I found partial support for this hypothesis in that inhibition was related to math problem s...

  7. Teachers’ ability in using math learning media

    Science.gov (United States)

    Masniladevi; Prahmana, R. C. I.; Helsa, Y.; Dalais, M.

    2017-12-01

    The studies aim to enhance teachers’ knowledge and skill in making math instructional media, develop math instructional media, train and assist the use of instructional media in learning math in the classroom. The method used in the activities adopted the pattern of preventive implementation, planning stage, program implementation, observation and evaluation and reflection. The research results show that the evaluation of teachers’ ability is still in average category. The result required more intensive training.

  8. Number-specific and general cognitive markers of preschoolers' math ability profiles.

    Science.gov (United States)

    Gray, Sarah A; Reeve, Robert A

    2016-07-01

    Different number-specific and general cognitive markers have been claimed to underlie preschoolers' math ability. It is unclear, however, whether similar/different cognitive markers, or combinations of them, are associated with different patterns of emerging math abilities (i.e., different patterns of strength and weakness). To examine this question, 103 preschoolers (40-60 months of age) completed six math tasks (count sequence, object counting, give a number, naming numbers, ordinal relations, and arithmetic), three number-specific markers of math ability (dot enumeration, magnitude comparison, and spontaneous focusing on numerosity), and four general markers (working memory, response inhibition, attention, and vocabulary). A three-step latent profile modeling procedure identified five math ability profiles that differed in their patterns of math strengths and weaknesses; specifically, the profiles were characterized by (a) excellent math ability on all math tasks, (b) good arithmetic ability, (c) good math ability but relatively poor count sequence recitation ability, (d) average ability on all math tasks, and (e) poor ability on all math tasks. After controlling for age, only dot enumeration and spontaneous focusing on numerosity were associated with the math ability profiles, whereas vocabulary was also marginally significant, and these markers were differentially associated with different profiles; that is, different cognitive markers were associated with different patterns of strengths and weaknesses in math abilities. Findings are discussed in terms of their implications for the development of math cognition. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. The Effectiveness of Verbal Self-Instruction Training on Math Problem-Solving of Intellectually Disabled Students

    Directory of Open Access Journals (Sweden)

    Masoume Pourmohamadreza-Tajrishi

    2015-12-01

    Full Text Available Objectives: The study was aimed to determine the effectiveness of verbal self-instruction training on math problem-solving of intellectually disabled boy students in Tehran Provinces. Methods: The study was a semi-experimental with pre-test and post-test design with control group. Thirty intellectually disabled boy students were selected randomly through cluster sampling method from 9th grade students. They were assigned to experimental and control group equally. Experimental group participated in 8 sessions and were trained by verbal self-instruction program but control group did not. All students answered to a teacher-made math problem-solving test before and after the training sessions. Data were analyzed by analysis of covariance. Results: Findings showed that there was a significant difference between two groups according to math problem-solving performance (P<0.002. Discussion: It can conclude that verbal self-instruction training probably leads to promote math problem-solving performance of intellectually disabled boy students.

  10. Thermal-kinetic study of natural rubber latex films vulcanized by using gamma radiation; Estudo termo-cinetico de filmes de latex de borracha natural de Hevea brasiliensis vulcanizada por radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Ana Paula Pinho Rodrigues; Barros, Glaucione Gomes de [Brasilia Univ., DF (Brazil). Inst. de Quimica; Guedes, Selma M.L. [Instituto de Pesquisa em Energia Nuclear, Sao Paulo, SP (Brazil)

    1999-07-01

    Vulcanization of natural rubber latex by ionization radiation produces the crosslink in disperse latex particles. Advantages over conventional process of vulcanization are: the absence of carcinogenic nitrosamines, low cytotoxicity and better degradation at room conditions, due to mainly to the absence of sulfur, zinc oxide and dithiocarbamates. Thermogravimetric analysis (TG) is the measurement of the weight change of a material as a function of temperature and time. TG data different heat speed provide an alternative model of the kinetics of degradation of polymeric materials. The kinetic studies of this material showed a single degradation process at least for 76,5% of mass loss. The activation energy was 49 Kcal/mol. For higher mass loss (85%) the degradation was characterized by associate mechanism. (author)

  11. Technology of Anticorrosive Protection of Steel Constructions by Coatings Based on Rapid-Hardening Bitumen-Latex Emulsion

    Directory of Open Access Journals (Sweden)

    Nykyforchyn, H.M.

    2016-01-01

    Full Text Available The recipes of rapid-hardening bitumen-latex emulsions and coatings on its base are created, in-laboratory tests of their physical, chemical and anticorrosive properties are carried out. The technology of anticorrosive protection and the installation technical documentation for making of aqueous bitumen-latex emulsion is developed, installation is mounted and a pilot lot of rapid-hardening emulsion is produced. Experimental-industrial approbation of the technology of coating formation on pipes in oil and gas industry is carried out.

  12. Isolation of natural inhibitors of papain obtained from Carica papaya latex

    Directory of Open Access Journals (Sweden)

    Rubens Monti

    2004-09-01

    Full Text Available Studies were carried out to natural papain inhibitor from papaya latex. Fresh latex from green fruits of Carica papaya was collected and immediately transported in ice bath to the lab, from which three fractions with inhibitor effect of esterase papain activity were isolated by latex dialysis, Sephadex G-25 gel filtration and ionic exchange chromatography in SP-Sephadex C-25. The isolated fractions, identified as inhibitors I and II, showed a negative reaction with ninhydrin; however, the fraction identified as P-III showed positive reaction with ninhydrin. Kinetics data showed non-competitive inhibition (inhibitor I and uncompetitive (inhibitors II and P-III.Este trabalho apresenta novos dados sobre inibidores naturais de papaína. O látex fresco de frutos verdes de Carica papaya foi coletado pela manhã em plantações da região de Araraquara, SP, Brasil e imediatamente transportado ao laboratório em banho de gelo. Três frações com efeito inibitório da atividade esterásica da papaína foram isoladas a partir do látex fresco, através de diálise, filtração em Sephadex G-25 e cromatografia em SP-Sephadex C-25. As frações isoladas identificadas como inibidores I e II, mostraram reação negativa à ninidrina; entretanto, a fração identificada como P-III mostrou reação positiva. Dados cinéticos revelaram inibição não-competitiva (inibidor I e incompetitiva (inibidores II e P-III.

  13. Simple arithmetic: not so simple for highly math anxious individuals.

    Science.gov (United States)

    Chang, Hyesang; Sprute, Lisa; Maloney, Erin A; Beilock, Sian L; Berman, Marc G

    2017-12-01

    Fluency with simple arithmetic, typically achieved in early elementary school, is thought to be one of the building blocks of mathematical competence. Behavioral studies with adults indicate that math anxiety (feelings of tension or apprehension about math) is associated with poor performance on cognitively demanding math problems. However, it remains unclear whether there are fundamental differences in how high and low math anxious individuals approach overlearned simple arithmetic problems that are less reliant on cognitive control. The current study used functional magnetic resonance imaging to examine the neural correlates of simple arithmetic performance across high and low math anxious individuals. We implemented a partial least squares analysis, a data-driven, multivariate analysis method to measure distributed patterns of whole-brain activity associated with performance. Despite overall high simple arithmetic performance across high and low math anxious individuals, performance was differentially dependent on the fronto-parietal attentional network as a function of math anxiety. Specifically, low-compared to high-math anxious individuals perform better when they activate this network less-a potential indication of more automatic problem-solving. These findings suggest that low and high math anxious individuals approach even the most fundamental math problems differently. © The Author (2017). Published by Oxford University Press.

  14. Natural membranes of Hevea brasiliensis latex as delivery system for Casearia sylvestris leaf components

    Directory of Open Access Journals (Sweden)

    Flávio A. Carvalho

    Full Text Available ABSTRACT Natural latex from Hevea brasiliensis (Wild. ex A.Juss Müll.Arg., Euphorbiaceae, showed angiogenic action and Casearia sylvestris Sw., Salicaceae, leaf derivatives presented anti-inflammatory and wound healing activities. Therefore, an association of these effects was interesting for wound healing applications. The aims of this study were the development of membranes of natural latex incorporated with C. sylvestris leaf derivatives (ethanolic extract, diterpene concentrated fraction and casearin J, their chemical and physical characterization, and the evaluation of in vitro skin permeation and retention of C. sylvestris bioactive secondary metabolites (diterpenes and phenolic compounds. The membranes were developed mixing hydroethanolic solutions of C. sylvestris derivatives with latex and drying them in a desiccator. They were characterized by infrared spectroscopy, scanning electron microscopy, water vapor permeability and mechanical resistance assays, demonstrating that all membranes were permeable, resistant and homogeneous in surfaces. The permeation and retention assays demonstrated dermal penetration of phenolic compounds for ethanolic extract membrane and of casearin-like clerodane diterpenes for all membranes, indicating that these membranes have great potential for therapeutical application as a topical system for C. sylvestris components releasing.

  15. Dragon Fruit Foliage Plant-Based Coagulant for Treatment of Concentrated Latex Effluent: Comparison of Treatment with Ferric Sulfate

    Directory of Open Access Journals (Sweden)

    Juferi Idris

    2013-01-01

    Full Text Available The effectiveness of dragon fruit foliage as a natural coagulant for treatment of concentrated latex effluent was investigated and compared with ferric sulfate, a chemical coagulant. Dragon fruit is a round and often red-colored fruit with scales-like texture and is native to south American countries which is also cultivated and heavily marketed in southeast Asian countries. Its foliage represents a part of its overall plant system. Latex effluent is one of the main byproduct from rubber processing factories in Malaysia. Three main parameters investigated were chemical oxygen demand (COD, suspended solids (SS, and turbidity of effluent. Coagulation experiments using jar test were performed with a flocculation system where the effects of latex effluent pH as well as coagulation dosage on coagulation effectiveness were examined. The highest recorded COD, SS, and turbidity removal percentages for foliage were observed for effluent pH 10 at 94.7, 88.9, and 99.7%, respectively. It is concluded that the foliage showed tremendous potential as a natural coagulant for water treatment purposes. The foliage could be used in the pretreatment stage of Malaysian latex effluent prior to secondary treatment.

  16. Banyan latex: a facile fuel for the multifunctional properties of MgO nanoparticles prepared via auto ignited combustion route

    International Nuclear Information System (INIS)

    Anil Kumar, M R; Nagaswarupa, H P; Gurushantha, K; Pratapkumar, C; Prashantha, S C; Shashishekar, T R; Anantharaju, K S; Nagabhushana, H; Sharma, S C; Vidya, Y S; Daruka Prasad, B; Vivek Babu, C S; Vishnu Mahesh, K R

    2015-01-01

    MgO nanoparticles (MNPs) were prepared by a solution combustion route using banyan tree (BT) latex and glycine as fuels. The powder x-ray diffraction results indicate the formation of a single cubic phase and the crystallite size obtained from transmission electron microscopy was found to be ∼10–15 nm. Scanning electron microscopy result reveals spherical-shaped particles obtained with BT latex. However, in a chemical route, porous and agglomerated particles were obtained. The energy band gap of MNPs obtained using BT latex and a chemical route were found to be in the range 4.85–5.0 eV. Photoluminescence peaks observed at 473, 514, and 588 nm when excited at 433 nm, which were attributed to surface defects. The enhanced photocatalytic activities of spherical MgO were due to smaller crystallite size, higher surface defects, dye sensitization, and capability to reduce the electron–hole pair recombination. Further, green-synthesized MNPs exhibit superior antifungal activity against various plant pathogens. The present studies demonstrated a green engineering route for the synthesis of multifunctional MNPs using BT latex. (paper)

  17. Characterization of papain-like isoenzymes from latex of Asclepias curassavica by molecular biology validated by proteomic approach.

    Science.gov (United States)

    Obregón, Walter D; Liggieri, Constanza S; Trejo, Sebastian A; Avilés, Francesc X; Vairo-Cavalli, Sandra E; Priolo, Nora S

    2009-01-01

    Latices from Asclepias spp are used in wound healing and the treatment of some digestive disorders. These pharmacological actions have been attributed to the presence of cysteine proteases in these milky latices. Asclepias curassavica (Asclepiadaceae), "scarlet milkweed" is a perennial subshrub native to South America. In the current paper we report a new approach directed at the selective biochemical and molecular characterization of asclepain cI (acI) and asclepain cII (acII), the enzymes responsible for the proteolytic activity of the scarlet milkweed latex. SDS-PAGE spots of both purified peptidases were digested with trypsin and Peptide Mass Fingerprints (PMFs) obtained showed no equivalent peptides. No identification was possible by MASCOT search due to the paucity of information concerning Asclepiadaceae latex cysteine proteinases available in databases. From total RNA extracted from latex samples, cDNA of both peptidases was obtained by RT-PCR using degenerate primers encoding Asclepiadaceae cysteine peptidase conserved domains. Theoretical PMFs of partial polypeptide sequences obtained by cloning (186 and 185 amino acids) were compared with empirical PMFs, confirming that the sequences of 186 and 185 amino acids correspond to acI and acII, respectively. N-terminal sequences of acI and acII, characterized by Edman sequencing, were overlapped with those coming from the cDNA to obtain the full-length sequence of both mature peptidases (212 and 211 residues respectively). Alignment and phylogenetic analysis confirmed that acI and acII belong to the subfamily C1A forming a new group of papain-like cysteine peptidases together with asclepain f from Asclepias fruticosa. We conclude that PMF could be adopted as an excellent tool to differentiate, in a fast and unequivocal way, peptidases with very similar physicochemical and functional properties, with advantages over other conventional methods (for instance enzyme kinetics) that are time consuming and afford less

  18. Preschool Math Exposure in Private Center-Based Care and Low-SES Children's Math Development

    Science.gov (United States)

    Bachman, Heather J.; Degol, Jessica L.; Elliott, Leanne; Scharphorn, Laura; El Nokali, Nermeen E.; Palmer, Kalani M.

    2018-01-01

    Research Findings: The present study examined the amount of exposure to math activities that children of low socioeconomic status (SES) encounter in private community-based preschool classrooms and whether greater time in these activities predicted higher math skills. Three cohorts of 4- to 5-year-old children were recruited from 30 private…

  19. Building a Math-Positive Culture: How to Support Great Math Teaching in Your School (ASCD Arias)

    Science.gov (United States)

    Seeley, Cathy L.

    2016-01-01

    Cathy L. Seeley, former president of the National Council of Teachers of Mathematics, turns the spotlight on administrative leaders who are seeking to improve their math programs, offering an overview of what an effective program looks like and examples of actions to take to achieve that goal. "Building a Math-Positive Culture" addresses…

  20. Neural correlates of math anxiety – an overview and implications

    OpenAIRE

    Artemenko, Christina; Daroczy, Gabriella; Nuerk, Hans-Christoph

    2015-01-01

    Math anxiety is a common phenomenon which can have a negative impact on numerical and arithmetic performance. However, so far little is known about the underlying neurocognitive mechanisms. This mini review provides an overview of studies investigating the neural correlates of math anxiety which provide several hints regarding its influence on math performance: while behavioral studies mostly observe an influence of math anxiety on difficult math tasks, neurophysiological studies show that pr...