Photoinduced orientation in natural rubber

Azobenzene molecules and their derivatives have been widely investigated for their potential applications in optical and electrooptical devices. We have prepared a new guest-host system from natural rubber (NR) impregnated with azobenzene derivative Sudan Red B (SRB). The effects of stretching and immersion time on photoinduced orientation were investigated by birefringence signal measurements. We have found that the molecular orientation increase when the samples are stretched and decrease with the increase of immersion time. The first behavior was explained by using the random coil model and the latter was attributed to increase of the aggregation of SRB into NR matrix. (C) 2012 Published by Elsevier B.V.

Natural rubber latex LbL films: Characterization and growth of fibroblasts

The recent biomedical applications of natural rubber (NR) latex, mostly in dry membranes, have motivated research into novel, more noble uses of this low-cost biomaterial. In this article, we provide the first report on the fabrication of layer-by-layer (LbL) films of NR alternated with the polyelectrolytes polyethylenimine (PEI) and polyallylamine hydrochloride (PAH). Stable (PAH/NR)n and (PEI/NR)n LbL films displayed similar physicochemical properties, but differed in terms of film morphology according to atomic force microscopy (AFM) and scanning electron microscopy (SEM) data. Most significantly, (PEI/NR)5 LbL films were made of smaller and flattened particles, which were not efficient for the growth and proliferation of normal human fibroblasts (NHF). In contrast, efficient NHF proliferation could be obtained with (PAH/NR)n LbL films, with the fibroblasts exhibiting the expected elongated morphology. Furthermore, cell growth did not occur for cast films of NR, thus demonstrating the suitability of the LbL method for this biologically related application. The differences between the two polyelectrolytes illustrate the importance of the film architecture and morphology, which open the way for exploiting the molecular control inherent in the LbL technique for further applications of NR-containing films. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Preparation and Structural Characterization of Vulcanized Natural Rubber Nanocomposites Containing Nickel-Zinc Ferrite Nanopowders

Single-phase polycrystalline mixed nickel-zinc ferrites belonging to Ni0.5Zn0.5Fe2O4 were prepared on a nanometric scale (mean crystallite size equal to 14.7 nm) by chemical synthesis named the modified poliol method. Ferrite nanopowder was then incorporated into a natural rubber matrix producing nanocomposites. The samples were investigated by means of infrared spectroscopy, X-ray diffraction, scanning electron microscopy and magnetic measurements. The obtained results suggest that the base concentration of nickel-zinc ferrite nanoparticles inside the polymer matrix volume greatly influences the magnetic properties of nanoconnposites. A small quantity of nanoparticles, less than 10 phr, in the nanocomposite is sufficient to produce a small alteration in the semi-crystallinity of nanocomposites observed by X-ray diffraction analysis and it produces a flexible magnetic composite material with a saturation magnetization, a coercivity field and an initial magnetic permeability equal to 3.08 emu/g, 99.22 Oe and 9.42 X 10(-5) respectively.

Yield and chemical properties of rubber of Hevea clones according to phenological stages

The objective of this work was to evaluate the yield performance and macronutrient content of rubber extracted from four Hevea brasiliensis clones, under different tapping systems and plant phenological stages. The experiment was carried out in the 2010 and 2011 crop seasons, in a split-plot randomized complete block design, with four replicates. The main treatments - GT 1, PB 235, IAN 873, and RRIM 600 clones - were allocated in the plots, and the secondary treatments, which were the tapping systems 1/2S d/2, 1/2S d/4 ET 2.5%, and 1/2S d/7 ET 2.5%, were allocated in the subplots. The analyzed variables were natural rubber yield and macronutrient contents. Samples of natural rubber were obtained in the leaf development, mature leaf, and leaf senescence phenological stages. Rubber yield and its macronutrient contents are more influenced by tapping practice than by genetic material in the restrictive phenological stages of foliage.

Attenuation of foot pressure during running on four different surfaces: asphalt, concrete, rubber, and natural grass

The practice of running has consistently increased worldwide, and with it, related lower limb injuries. The type of running surface has been associated with running injury etiology, in addition other factors, such as the relationship between the amount and intensity of training. There is still controversy in the literature regarding the biomechanical effects of different types of running surfaces on foot-floor interaction. The aim of this study was to investigate the influence of running on asphalt, concrete, natural grass, and rubber on in-shoe pressure patterns in adult recreational runners. Forty-seven adult recreational runners ran twice for 40 m on all four different surfaces at 12 +/- 5% km . h(-1). Peak pressure, pressure-time integral, and contact time were recorded by Pedar X insoles. Asphalt and concrete were similar for all plantar variables and pressure zones. Running on grass produced peak pressures 9.3% to 16.6% lower (P < 0.001) than the other surfaces in the rearfoot and 4.7% to 12.3% (P < 0.05) lower in the forefoot. The contact time on rubber was greater than on concrete for the rearfoot and midfoot. The behaviour of rubber was similar to that obtained for the rigid surfaces - concrete and asphalt - possibly because of its time of usage (five years). Running on natural grass attenuates in-shoe plantar pressures in recreational runners. If a runner controls the amount and intensity of practice, running on grass may reduce the total stress on the musculoskeletal system compared with the total musculoskeletal stress when running on more rigid surfaces, such as asphalt and concrete.

Fracture and resistance-curve behavior in hybrid natural fiber and polypropylene fiber reinforced composites

This article presents the results of a combined experimental and theoretical study of fracture and resistance-curve behavior of hybrid natural fiber- and synthetic polymer fiber-reinforced composites that are being developed for potential applications in affordable housing. Fracture and resistance-curve behavior are studied using single-edge notched bend specimens. The sisal fibers used were examined using atomic force microscopy for fiber bundle structures. The underlying crack/microstructure interactions and fracture mechanisms are elucidated via in situ optical microscopy and ex-situ environmental scanning microscopy techniques. The observed crack bridging mechanisms are modeled using small and large scale bridging concepts. The implications of the results are then discussed for the design of eco-friendly building materials that are reinforced with natural and polypropylene fibers.

WOOD NATURAL RESISTANCE OF SEVEN FOREST SPECIES TO WHITE ROT CAUSED BY Pycnoporus sanguineus

This research evaluated the natural resistance of Platanus x acerifolia, Luehea divaricate, Carya illinoinensis, Peltophorum dubium, Araucaria angustifolia, Eucalyptus grandis and Hovenia dulcis, to accelerated decay of the white-rot fungus Pycnoporus sanguineus. The Specific Density at 12% was determinated. The accelerated decay test was conducted with glass bottles (capacity of 500 mL) filled with 100 g of moist soil, autoclaved, and kept at 25 degrees C. The initial establishment of fungal colonies on plates was supported by samples of Pinus elliottii sapwood. In this study, three samples of dimensions 9.0 x 25.0 x 25.0 mm were used for each species evaluated and, after 16 weeks of incubation, the percentage loss of mass was calculated. The degree of natural resistance was performed according to the percentages of mass loss. The results obtained from weight loss were compared by Tukey test at 5%. The natural resistance of woods was not influenced by specific gravity The wood of Carya illinoinensis, Eucalyptus grandis, Platanus x acerifolia, Luehea divaricata and Peltophorum dubium were classified as very resistant, Houvenia dulcis as resistant and Araucaria angustifolia as moderate resistant.

Anatomical and functional evaluation of tympanoplasty using a transitory natural latex biomembrane implant from the rubber tree Hevea brasiliensis

PURPOSE: To compare the role of transitory latex and sylastic (R) implants in tympanoplasty on the closure of tympanic perforations. METHODS: A randomized double-blind prospective study was conducted on 107 patients with chronic otitis media submitted to underlay tympanoplasty and divided at random into three groups: control with no transitory implant, latex membrane group, and sylastic (R) membrane group. RESULTS: Greater graft vascularization occurred in the latex membrane group (p<0.05). Good biocompatibility was obtained with the use of the latex and silicone implants, with no effect on the occurrence of infection, otorrhea or otorragy. CONCLUSION: The use of a transitory latex implant induced greater graft vascularization, with a biocompatible interaction with the tissue of the human tympanic membrane.

Immunological parameters in elderly women: Correlations with aerobic power, muscle strength and mood state

Purpose: Our objective was to relate immunological data for healthy but sedentary elderly women to aerobic power, strength, and mood state. Methods: We measured peak aerobic power and one-repetition maximum strength along with mood (depression and fatigue), quality of life and carbohydrate intake on 42 women aged 60-77 years. Standard immunological techniques determined natural killer cell count and cytotoxic activity (NKCA), proliferative responses to phytohemaglutinin and OKT3, various lymphocyte subpopulations (CD3(+), CD3(-)CD19(+), CD56(+), CD4(+), CD8(+), CD56(dim) and CD56(bright)), and markers of activation, maturation, down-regulation and susceptibility to apoptosis (CD25(+), CD28(+), CD45RA(+), CD45RO(+), CD69(+), CD95(+), HLA-DR+). Results: Correlations of immune parameters with aerobic power and strength were very similar for absolute and relative immunological data. In the group as a whole, the only correlation with aerobic power was -0.35 (relative CD4(+)CD69(+) count), but in subjects with values <22.6 mL kg(-1) min(-1) correlations ranged from -0.57 (relative CD4(+)CD45RO(+)) to 0.92 (absolute CD56(dim)HLA-DR+). In terms of muscle strength, univariate correlation coefficients ranged from -0.34 (relative and absolute CD3(+)CD4(+)CD8(+)) to +0.48 (absolute CD3(+)HLA-DR+.) and +0.50 (absolute CD8(+)CD45RA(+)CD45RO(+)). Neither NKCA nor lymphocyte proliferation were correlated with aerobic power or muscle strength. Although mood state and quality of life can sometimes be influenced by an individual's fitness level, our multivariate analyses suggested that depression, fatigue and quality of life were more important determinants of immune profile than our fitness measures. Conclusions: Psychological changes associated with aging may have a substantial adverse effect upon the immune system, and immunological function may be enhanced more by addressing these issues than by focusing upon aerobic or resistance training. (C) 2012 Elsevier Inc. All rights reserved.

Mapping of angular leaf spot resistance QTL in common bean (Phaseolus vulgaris L.) under different environments

Background: Common bean (Phaseolus vulgaris L.) is the most important grain legume for human diet worldwide and the angular leaf spot (ALS) is one of the most devastating diseases of this crop, leading to yield losses as high as 80%. In an attempt to breed resistant cultivars, it is important to first understand the inheritance mode of resistance and to develop tools that could be used in assisted breeding. Therefore, the aim of this study was to identify quantitative trait loci (QTL) controlling resistance to ALS under natural infection conditions in the field and under inoculated conditions in the greenhouse. Results: QTL analyses were made using phenotypic data from 346 recombinant inbreed lines from the IAC-UNA x CAL 143 cross, gathered in three experiments, two of which were conducted in the field in different seasons and one in the greenhouse. Joint composite interval mapping analysis of QTL x environment interaction was performed. In all, seven QTLs were mapped on five linkage groups. Most of them, with the exception of two, were significant in all experiments. Among these, ALS10.1(DG,UC) presented major effects (R-2 between 16% - 22%). This QTL was found linked to the GATS11b marker of linkage group B10, which was consistently amplified across a set of common bean lines and was associated with the resistance. Four new QTLs were identified. Between them the ALS5.2 showed an important effect (9.4%) under inoculated conditions in the greenhouse. ALS4.2 was another major QTL, under natural infection in the field, explaining 10.8% of the variability for resistance reaction. The other QTLs showed minor effects on resistance. Conclusions: The results indicated a quantitative inheritance pattern of ALS resistance in the common bean line CAL 143. QTL x environment interactions were observed. Moreover, the major QTL identified on linkage group B10 could be important for bean breeding, as it was stable in all the environments. Thereby, the GATS11b marker is a potential tool for marker assisted selection for ALS resistance.

THE PERCEPTION AND UNDERSTANDING OF HEALTH PROFESSIONALS AND UNDERGRADUATE STUDENTS REGARDING AGING AND THE ELDERLY

This qualitative study was developed with 117 healthcare professionals and undergraduate students who were participants of a non-verbal communication training program in gerontology, with the objective to identify the perception and understanding of healthcare undergraduates and graduates regarding aging and the elderly. The results allowed the construction of the following categories: an evolution of life that brings a variety of experiences; natural, mysterious and with accumulated experiences; a decrease in overall happiness due to an increase in isolation; a time of valuing affection and respect; an inevitable stage including distress, prejudice, and limitations worthy of attention; a natural consequence of life; and the presence of disease and the global physiological process. Regarding perceptions of the elderly, the answers were classified as positive, negative, mixed and neutral. We considered that the understanding regarding the elderly and aging was limited and pessimist, indicating a need to become aware that one's views affect the way we relate to others.

Molecular evolution of a malaria resistance gene (DARC) in primates

Genes involved in host-pathogen interactions are often strongly affected by positive natural selection. The Duffy antigen, coded by the Duffy antigen receptor for chemokines (DARC) gene, serves as a receptor for Plasmodium vivax in humans and for Plasmodium knowlesi in some nonhuman primates. In the majority of sub-Saharan Africans, a nucleic acid variant in GATA-1 of the gene promoter is responsible for the nonexpression of the Duffy antigen on red blood cells and consequently resistance to invasion by P. vivax. The Duffy antigen also acts as a receptor for chemokines and is expressed in red blood cells and many other tissues of the body. Because of this dual role, we sequenced a 3,000-bp region encompassing the entire DARC gene as well as part of its 5' and 3' flanking regions in a phylogenetic sample of primates and used statistical methods to evaluate the nature of selection pressures acting on the gene during its evolution. We analyzed both coding and regulatory regions of the DARC gene. The regulatory analysis showed accelerated rates of substitution at several sites near known motifs. Our tests of positive selection in the coding region using maximum likelihood by branch sites and maximum likelihood by codon sites did not yield statistically significant evidence for the action of positive selection. However, the maximum likelihood test in which the gene was subdivided into different structural regions showed that the known binding region for P. vivax/P. knowlesi is under very different selective pressures than the remainder of the gene. In fact, most of the gene appears to be under strong purifying selection, but this is not evident in the binding region. We suggest that the binding region is under the influence of two opposing selective pressures, positive selection possibly exerted by the parasite and purifying selection exerted by chemokines.

Wear and corrosion resistance of pack chromised carbon steel

Pack chromising treatment is an environmentally friendly alternative to hard chromium to form wear and corrosion resistant surface layers. In this work, samples of AISI 1060 steel were pack chromised for 6 and 9 h at 1000 and 1050 degrees C using different activator concentrations. Wear tests were performed in dry conditions and corrosion tests in natural sea water for the pack chromised samples and hard chromium. Pack chromising yielded the formation of layers with high chromium concentrations, high hardness and wear resistance. Increasing activator concentration causes no significant change on the morphology and thickness of the layers. The layers produced at 1050 degrees C yielded only a (Cr,Fe)(2)N1-x phase, and those obtained at 1000 degrees C are composed of a carbide mixture with (Cr,Fe)(2)N1-x. The sample treated at 1050 degrees C for 9 h resulted in an optimum condition by means of better wear resistance and corrosion properties, which were close to that exhibited by the hard chrome, indicating that pack chromising is a promising alternative.

AEROBIC OR RESISTANCE EXERCISE IMPROVES PERFORMANCE IN ACTIVITIES OF DAILY LIVING IN ELDERLY WOMEN

The purpose of this randomized non-controlled study was to determine the effect of an aerobic or resistance exercise protocol on performance of activities of daily living in elderly women. The sample was constituted of 41 apparently healthy elderly women aged 60 to 85 years (x: 65.1 +/- 7.9 years) randomly assigned in resistance exercise (n: 22) or aerobic groups (n: 19). The resistance exercise protocol consisted of three sets of eight to 12 repetitions at 60% of one repetition maximum test for the leg press 45 degrees. The aerobic exercise protocol consisted in cycling in a cycle ergometer during 40 minutes at 60% of reserve heart rate. Both protocols were performed three times per week during five weeks. Activities of daily living were estimated by velocity to stand from sitting to standing position (VSitting), velocity to move from supine to standing position (VSupine), velocity to climb stairs (VCS) and velocity to wear sneakers (VWS). Volunteers of aerobic exercise protocol improved significantly the time to perform VWS (19.1%), while the volunteers of resistance exercise protocol improved the capacity to perform VCS (4.3%) and VSupine (8.9%). These results let us conclude that aerobic as well as resistance exercise protocols induced positive effect on activities of daily living, suggesting that both protocols must be associated for an adequate exercise program to improve the functional capacity of elderly people.

Exploration of the parameter space in an agent-based model of tuberculosis spread: emergence of drug resistance in developing vs developed countries

In this work we present an agent-based model for the spread of tuberculosis where the individuals can be infected with either drug-susceptible or drug-resistant strains and can also receive a treatment. The dynamics of the model and the role of each one of the parameters are explained. The whole set of parameters is explored to check their importance in the numerical simulation results. The model captures the beneficial impact of the adequate treatment on the prevalence of tuberculosis. Nevertheless, depending on the treatment parameters range, it also captures the emergence of drug resistance. Drug resistance emergence is particularly likely to occur for parameter values corresponding to less efficacious treatment, as usually found in developing countries.