Natural Exposure Conditions Research Articles

Attention to food health warnings in children's advertising: a French perspective

ObjectivesThe objective of this study was to evaluate how much attention children pay to health warnings displayed on TV and print advertisements promoting drinks with added sugar, salt, or artificial sweeteners, and processed food products. Study designThe research was conducted in France among 50 children, using an eye-tracking system to record participants’ eye movements on TV and print advertisements. MethodsTo reproduce the natural exposure conditions to TV commercials, the children were asked to watch a 12-min extract of an animated comedy film with two commercial breaks sandwiched between the extract. For the print ads, all the children were exposed to eight ads. The use of an eye-tracking system gave an objective measurement of the attention paid to the food health warnings. ResultsThe results show that children exposed to these food product advertisements pay little or no attention to the warnings. Only 18% of the children made more than one eye fixation on the central message of the health warnings (the part displaying the health recommendation) for TV commercials, and almost no attention was given to warnings displayed on the print ads. ConclusionsThis study shows that the French authorities should take stronger and more decisive measures to help children adopt healthy behavior because the current health warnings appear insufficient to inform children.

Comportamiento de la rugosidad superficial del acero luego de exposición natural en exterior e interior

Knowledge of the phenomena that take place in the environment that surrounds us, ensures the preservation and proper use of resources, raising the quality of life on the planet for the present and future well-being of the men who inhabit it. One of the natural processes that we face each and every one of the beings that coexist on this planet, whether alive or not, is the deterioration due to interaction with the environment. The most natural form of deterioration in which metals return to minerals, as they are found in nature, is known as corrosion, a process that is affected by multiple environmental factors. The surface condition of a metal sample is an aspect that infl uences the magnitude and type of corrosion. In the present work we evaluated the behavior of the surface roughness in conditions of natural exposure in exteriors and interiors during a short time of 360 h. Based on the multifactorial design, the incidence of exposure conditions and the test time on surface roughness with a 95% confidence level are demonstrated. The equations of the linear model describe the relationship between surface roughness and exposure time, making possible predictions in the future for climate conditions similar to those described in the study.

Model for practical carbonation depth prediction for high volume fly ash concrete and recycled aggregate concrete

Abstract The reuse of industrial residue streams such as fly ash (FA) or waste materials such as recycled concrete aggregate (RCA) can be beneficial both from an economic and an ecological point of view. Extensive research, investigating different properties of these concrete types, has been carried out so far. However, durability remains a key property ensuring sustainable application of these materials in the construction sector that still needs more research to be fully understood. The main objective of this study was to evaluate the application of widely used models for carbonation depth prediction—defined for ordinary Portland cement concrete with natural aggregate (NAC)—to high volume FA concrete (HVFAC) and recycled aggregate concrete (RAC). The research presented in this paper was conducted in two steps. First, an experimental programme was designed to provide better understanding of the influence of different CO2 concentrations on the carbonation process kinetics in HVFAC, RAC and NAC. This was performed using accelerated carbonation tests (CO2 concentrations of 1%, 2%, 4% and 16%) and natural carbonation tests (duration 21 and 48 months). Furthermore, a database of previously published results of HVFAC and NAC carbonation depths was made in order to analyse the application of carbonation depth prediction defined by Tuutti and given in the fib Model Code 2010. It was shown that the existing models, providing the relationship between accelerated test results and natural carbonation depth, are applicable to NAC and RAC but not to HVFAC. Modifications of the above mentioned models were proposed in order to enable a more accurate and reliable prediction of the HVFAC carbonation depth under natural exposure conditions.

Influence of 6PPD Stabilizer on Climatic Stability of Rubbers Based on Butadiene-Nitrile and Epichlorohydrin Rubbers

The present paper outlines the results of full-scale tests of climatic stability and the study of resistance to the action of hydrocarbon media of rubbers based on BNKS-18-18 (butadiene-nitrile rubber) and Hydrin T6000 epichlorohydrin rubber containing one of 6PPDstabilizerwith an aromatic amine moiety widely used in synthetic rubbers. Samples are exposed in an open ground under natural conditions of exposure to climatic external factors of Yakutsk in the Republic of Sakha (Yakutia), as well as in the oil environment of Talakanskoye field and I-50A hydraulic fluid in an unheated room. Such indexes of the samples as conditional tensile strength, elongation at rupture, hardness and degree of swelling are measured to determine the resistance of rubbers to aging after the first, third, and sixth months of exposing. The results of the study reveal the contribution of 6PPD stabilizer in maintaining the stability of the physical and mechanical properties of BNKS-18: rubber containing 6PPD has less property changes both in the open air and in hydrocarbon media compared to rubber without a stabilizer. It should be noted that the oil environment is the most aggressive environment, the swelling of rubbers in oil leads to a significant reduction in strength due to a decrease in intermolecular interaction.6PPD stabilizer occurred less effective for the rubber based on Hydrin T6000: changes in properties of the samples containing the stabilizer are larger than those of the samples without the stabilizer. However, unlike BNKS-18-18-based rubber, the swelling of rubber based on Hydrin T6000 led to the greatest stability of the physical and mechanical properties in the oil environment compared to the open air and hydraulic fluids.

The effect of relative humidity change on atmospheric pitting corrosion of stainless steel 304L

Relative humidity fluctuations tend to influence atmospheric corrosion under natural exposure conditions. In this study, the effect of change in relative humidity on pitting corrosion of stainless steel under MgCl2 droplets is investigated with in situ X-ray microtomography and optical microscopy. Relative humidity fluctuations (between 33% RH and 85% RH or between 33% RH and 12% RH) tend to lead to nucleation of many small pits whereas continuous exposure at constant 33% RH leads to growth of a single pit. This indicates that natural fluctuations in relative humidity might be beneficial for preventing the growth of a large penetrating pit.

Influence of Clay Minerals Nature on the Hydromechanical and Fracture Behaviour of Stones

Elastic properties and fracture behaviour evolutions of two sedimentary stones are under study to estimate their influence on scaling effect of monumental stone heritage. Young moduli and toughness of Villarlod molasse and Thüringer sandstone are measured under moisture content variations with respect to their natural anisotropy. Several relative humidity levels are considered to investigate their effect upon humidification and drying. The stone property evolution is in close correlation with the identified clay phases of the matrix. It appears that clay minerals as smectite and glauconite influence the stone properties at very low moisture contents, whereas less swelling clays have impact only when high moisture contents are reached. This is in close correlation with the inherent deformation ability of these minerals. It is observed that nature and distribution of clay phases largely influence on the macroscopic behaviour under natural exposure conditions, as they modify the stone properties and represent the weakness planes of the stone.

Response of Asymmetric Slim Floor Beams in Parametric-Fires

State-of-the-art slim floor systems are a newest addition to the composite construction industry and several types are currently being used for building and construction purposes. Asymmetric slim floor beams are a type of slim floor systems which consist of a rolled section with a larger bottom flange. The larger bottom flange induces asymmetry and offers an efficient use of the material strength as a composite beam. It also offers a larger area to support the steel decking and pre-cast slab units during the construction of floor. Experimental and analytical investigations on response of asymmetric slim floor beams have shown that these beams offer a higher fire resistance in comparison to the conventional composite systems with down-stand steel beams. Previous investigations on these beams have been conducted in standard fire exposure conditions, hence, their response to natural fire scenarios still deems further examination. This study addresses response of asymmetric slim floor beams in natural fire exposure conditions. For this purpose, finite element models developed and verified by the authors are employed to study the thermal and structural response of slim floor beams in fast and slow parametric-fire exposures. Results obtained show that the asymmetric slim floor beams behave differently in parametric-fires in comparison to that in standard fire exposure conditions. Asymmetric slim floor beams continued to support the loads for the whole duration of parametric fires without undergoing excessive deflections and offering a better fire resistance. Unlike in case of the standard fire where the temperatures keep on increasing throughout the duration, temperatures on the slim floor beams decrease after reaching a maximum point in parametric-fires. It was found that for fast parametric-fires, the thermal gradient across the section is more severe as compared to that for the slow parametric-fires at earlier stages of fire exposure. In case of the fast parametric-fires, the rise and fall of temperatures on the slim floor beams are rapid while in case of the slow parametric-fire, these variations in temperatures are subtle. It was observed that the structural response of slim floor beams in standard and parametric fires depends on the average temperature across the steel section. Deflections predicted for the beams were found to be directly related to these average temperatures. Outcomes of this study will benefit in understanding the response of asymmetric slim floor beams in natural fire conditions and will aid to develop simple fire design methods for future use.

Improved volume stability of mortar bars exposed to magnesium sulfate in the presence of bicarbonate ions

The effect of the simultaneous occurrence of sulfate and bicarbonate ions in magnesium containing solutions was investigated for a CEM I and CEM III/B mortar under laboratory conditions. The presence of bicarbonate ions, which is common in natural waters, prevents the typical expansion and surface erosion of CEM I mortars and the surface deterioration of CEM III/B mortars. The chemical effect of the bicarbonate ions is twofold. The precipitation of CaCO3 lowers the availability of CaO for the formation of additional sulfate bearing phases like ettringite and gypsum. The second effect is the reduction of supersaturation of the pore solution with respect to ettringite. The absence of deterioration is linked to the formation of only small amounts of ettringite and to the absence of gypsum in the affected zones. Thermodynamic modeling suggests that relatively small bicarbonate concentrations suffice to prevent damage, contribute to the scarcity of damage under natural exposure conditions and to the diversity of results under laboratory exposure conditions.

Long-Term Behavior of Carbon Steel in Alkaline Nitrate Solutions Related to Radioactive Waste Storage

Radioactive wastes from the processing of nuclear materials used for weapons production have been stored in underground carbon steel tanks for the past several decades. The waste solutions are a complex mixture of a variety of anionic and cationic species, dominated by sodium nitrates, nitrites, and hydroxide. It has been well established that localized corrosion and stress corrosion cracking of carbon steel can occur in these solutions above certain critical potentials that are determined by the anionic species and temperature. Recent studies have shown that the corrosion potential increases significantly over a period of weeks to months, such that there is a concern about exceeding the critical potentials under natural conditions of exposure. This paper discusses the evolution of the corrosion potential of steel in alkaline solutions (pH >11) in comparison to the critical potentials. The impedance behavior of the steel in these solutions shows changes in the semi-conductive behavior over time as well as the density of charge carriers that may influence the evolution of corrosion potential. The effect of the changes in corrosion potential on localized corrosion and stress corrosion cracking is discussed.

Effect of mix design inputs, curing and compressive strength on the durability of Na2SO4-activated high volume fly ash concretes

This paper aims to advance research on the use in concrete of a high volume of fly ash, with a high loss on ignition value, aiding in sustainable low carbon footprint construction. To this end, the work explores the benefits that may be achieved in terms of long-term concrete performance from the incorporation of fly ash along with a chemical activator. Durability tests are performed on concrete with an activated hybrid cementitious system: Portland cement (PC) and high volume fly ash with sodium sulfate. The chloride diffusion coefficient significantly decreased over time for the activated system (50% PC - 50% fly ash with added sodium sulfate) compared to the control samples (100% PC and 80% PC - 20% fly ash) at the same water to cementitious material ratio. This behavior is particularly evident in samples cured under controlled laboratory conditions (100% RH and 23 °C). However, outdoor curing increases the permeability for all concretes. Long term carbonation is also investigated under natural exposure conditions, and samples that are cured outdoors exhibit a significant carbonation depth. The compressive strength is correlated with the durability parameters: the durability performance improves as the compressive strength increases, indicating that as is the case for Portland cement (but not always for alkali-activated binders), the microstructural factors which yield high strength are also contributing to durability properties.

Synthetic Antigens Derived from Plasmodium falciparum Sporozoite, Liver, and Blood Stages: Naturally Acquired Immune Response and Human Leukocyte Antigen Associations in Individuals Living in a Brazilian Endemic Area.

Peptide vaccine strategies using Plasmodium-derived antigens have emerged as an attractive approach against malaria. However, relatively few studies have been conducted with malaria-exposed populations from non-African countries. Herein, the seroepidemiological profile against Plasmodium falciparum of naturally exposed individuals from a Brazilian malaria-endemic area against synthetic peptides derived from vaccine candidates circumsporozoite protein (CSP), liver stage antigen-1 (LSA-1), erythrocyte binding antigen-175 (EBA-175), and merozoite surface protein-3 (MSP-3) was investigated. Moreover, human leukocyte antigen (HLA)-DRB1* and HLA-DQB1* were evaluated to characterize genetic modulation of humoral responsiveness to these antigens. The study was performed using blood samples from 187 individuals living in rural malaria-endemic villages situated near Porto Velho, Rondônia State. Specific IgG and IgM antibodies and IgG subclasses were detected by enzyme-linked immunosorbent assay, and HLA-DRB1* and HLA-DQB1* low-resolution typing was performed by PCR-SSP. All four synthetic peptides were broadly recognized by naturally acquired antibodies. Regarding the IgG subclass profile, only CSP induced IgG1 and IgG3 antibodies, which is an important fact given that the acquisition of protective immunity appears to be associated with the cytophilicity of IgG1 and IgG3 antibodies. HLA-DRB1*11 and HLA-DQB1*7 had the lowest odds of responding to EBA-175. Our results showed that CSP, LSA-1, EBA, and MSP-3 are immunogenic in natural conditions of exposure and that anti-EBA antibody responses appear to be modulated by HLA class II antigens.

Investigation into the rate of natural carbonation of concrete blocks under Irish production yard conditions

The release of CO2 from calcination during the manufacture of cement can be partially offset by the CO2 it naturally absorbs during its lifetime. This paper reports results from a preliminary investigation into the rate of carbonation in concrete blocks stacked in a production yard over a period of 6 months. The blocks were organised in a normal manner under natural exposure conditions. Carbonation progress was determined using phenolphthalein. It was found that the rate of the carbonation front progression differed depending on the exposure face and block type. Carbonation fronts on exposed front (FF) or side faces (SF) were seen to advance at rates of over 1 mm/week for the initial 6 months of exposure. Exposed top faces (TF) showed a slower rate of carbonation of just over 0.6 mm/week. The speed of the advance of the carbonation front into concrete slowed over time, however, it was noted that slower progression occurred during the second half of testing over the winter period. Rates of carbonation and estimates of carbon sequestration were calculated. The findings suggest that carbonation should be included in the manufacturing stage of life cycle assessments for open textured concrete products such as blocks.

Multivariate correlation analysis of outdoor weathering behavior of polypropylene under diverse climate scenarios

A full understanding on the relationships between weathering factors and deteriorations in the physical or mechanical properties of polymeric materials as well as their intercorrelations is critically important to forecast the durability of materials. In this work, the outdoor weathering behaviors of isotactic polypropylene (iPP) across a 1.5-year period under six typical climate scenarios in China are investigated. A wide sets of natural exposure conditions and test methods allow the establishment of the substantial correlations between chemical/physical structures and appearance/mechanical properties under simultaneous effects of multiple weathering factors (such as light, heat, oxygen etc.). The results under diverse natural environments suggest that the crystallinity and crack development depend largely on the molecular weight while the yellowing index correlates directly with the carbonyl index irrespective of the exposure conditions. The relationship between tensile strength and molecular weight is found to be in accord with an empirical linear model. Subsequently, using principal component analysis (PCA), a data reduction and visualization method, the degradation risk map of PP materials in China is established and the relative importance of relevant weathering factors is evaluated. Temperature is found to be the most dominant weathering factor on iPP aging under the climate scenarios investigated in the present work.

Statistical modelling of the influential factors on chloride penetration in concrete

It is widely acknowledged that reinforcing steel corrosion is the most common deterioration mechanism in reinforced concrete structures and that chloride penetration is one of the processes that induce such a mechanism. Although chloride ingress in concrete has been thoroughly investigated, it is still difficult to foresee, in a quantitative manner, the performance of a given concrete mix regarding chloride penetration over time. This work intends to provide simple analytical models to the prediction of concrete's performance with respect to chloride penetration, conveying it in the form of a diffusion coefficient. For that purpose, a comprehensive sample of 493 case studies were collected from 43 publications. The statistical modelling is performed using a multiple linear regression. This approach allowed identifying explanatory variables to this phenomenon and its transposition to mathematical models. This paper presents three analytical models to characterize the resistance of concrete to chloride penetration. A general model to estimate chloride diffusion coefficients is proposed, as well as two specific models, one for natural exposure conditions and the other for migration tests. The physical meaning of the variables considered in the models was discussed, allowing a comprehensible description of chloride penetration in concrete.

Circadian Rhythms: The Price of Electric Light

A new study demonstrates that modern electric lighting has caused the near-24-hour biological clock to be set to a later time and that humans physiologically respond to seasonal changes in day length under conditions of natural light exposure.

A new meta-model to calculate carbonation front depth within concrete structures

Carbonation processes cannot be ignored as regards durability and service-life of new concrete structures, and their correct understanding and quantification are essential for maintenance and repair works on existing structures. This paper initially presents a new meta-model developed to calculate carbonation front depth based on the analytic solution of Fick’s first law. The only input data required by this non numerical model are: (i) material variables (concrete mix design, maximum nominal aggregate size, cement type, and chemical composition of cement type CEM I and cement density); (ii) technological parameters (initial curing period (tc)); (iii) environmental parameters (ambient temperature (T), relative external humidity (RH) and CO2 concentration in the air ([CO2]ext)). Consequently, this model is fully suitable for the prediction of carbonation depth in the case of new reinforced concrete structures, for which these required parameters are well-known. The meta-model is validated using data from the literature on short and long-term natural carbonation exposure conditions. Most of the experimental data concern CEM I, CEM II, CEM III cement types, and CEM I additives (fly ash (FA)) with various water to cement (W/C) ratios and tc. The meta-model is also compared with two already available models: Papadakis’ model and Yang’s model. The three model predictions are compared with the corresponding values found in the literature. The results confirm that the prediction of the new meta-model proposed here for estimation of carbonation depth is the most accurate in every case.

Longevity of Genotype-Specific Immune Responses to Plasmodium falciparum Merozoite Surface Protein 1 in Kenyan Children from Regions of Different Malaria Transmission Intensity.

Naturally acquired immunity to Plasmodium falciparum presents a changing landscape as malaria control programs and vaccine initiatives are implemented. Determining which immunologic indicators remain surrogates of past infection, as opposed to mediators of protection, led us to compare stability of immune responses across regions with divergent malaria transmission intensities. A repeat cross-sectional study of Kenyan children from a malaria-holoendemic area and an epidemic-prone area was used to examine longitudinal antibody and interferon-gamma (IFN-γ) responses to the 3D7 and FVO variants of merozoite surface protein 1 (MSP1). Antibodies to MSP1 were common in both study populations and did not significantly wane over a 21-month time period. IFN-γ responses were less frequent and rapidly disappeared in children after a prolonged period of no malaria transmission. Antibody and IFN-γ responses rarely correlated with each other; however, MSP1-specific IFN-γ response correlated with lack of concurrent P. falciparum parasitemia of the same genotype, though only statistically significantly in the malaria-holoendemic region (odds ratio = 0.31, 95% confidence interval = 0.12-0.84). This study affirms that antimalarial antibodies are informative for evaluation of history of malaria exposure within individuals, whereas cell-mediated immunity, though short lived under natural exposure conditions, might provide an assessment of recent infection and protection from parasitemia.

Dirofilaria immitis exposure status in client-owned cats with or without lower airway/lung-associated signs: case-control study in a canine heartworm-endemic area.

Objectives Heartworm-associated respiratory disease (HARD) is a recently recognised pathological manifestation in cats caused by Dirofilaria immitis exposure. This study aimed to estimate the percentage of cats at risk of developing HARD in a heartworm-endemic area (Taipei, Taiwan), and to test the correlation of heartworm exposure and the presence of lower airway/lung clinical signs (LA/L signs). Methods This was a prospective case-control study. The study design called for the enrolment of at least 80 cats with LA/L signs and at least 80 cats without such clinical signs in a 1 year period. The D immitis antibody seroprevalence of the two cohorts was compared. Results From February 2014 to January 2015, 187 client-owned cats were prospectively enrolled: 83 clinical cases with LA/L signs and 104 cats without such signs. Antibody seropositivity was approximately twice as frequent in cats with LA/L signs (13.3%) than in cats without signs (7.8%) (odds ratio [OR] 1.814); nevertheless, no statistically significant difference between the two cohorts ( P = 0.22) was found. We used 41 frozen samples from free-roaming cats to examine the possibility of different exposure rates to mosquito bites between client-owned cats and stray cats, finding the seroprevalence to be 7.5% in free-roaming cats - a result not statistically different to that in client-owned cats ( P = 0.60). Outdoor access was a significant risk factor for heartworm exposure in client-owned cats (OR 3.748; P = 0.03); however, living entirely indoors did not provide complete protection from exposure/infection. Conclusions and relevance Our results did not show statistically significant differences in antibody seroprevalence between cats with and without LA/L signs. LA/L signs were not always present under conditions of natural exposure. However, exposure to D immitis is not rare among client-owned cats, suggesting that heartworm prophylactics should be a part of routine care in all cats living in areas endemic for canine heartworm.

Thermo-Mechanical Compatibility of Viscoelastic Mortars for Stone Repair.

The magnitude of the thermal stresses that originate in an acrylic-based repair material used for the reprofiling of natural sandstone is analyzed. This kind of artificial stone was developed in the late 1970s for its peculiar property of reversibility in an organic solvent. However, it displays a high thermal expansion coefficient, which can be a matter of concern for the durability either of the repair or of the underlying original stone. To evaluate this risk we propose an analytical solution that considers the viscoelasticity of the repair layer. The temperature profile used in the numerical evaluation has been measured in a church where artificial stone has been used in a recent restoration campaign. The viscoelasticity of the artificial stone has been characterized by stress relaxation experiments. The numerical analysis shows that the relaxation time of the repair mortar, originating from a low , allows relief of most of the thermal stresses. It explains the good durability of this particular repair material, as observed by the practitioners, and provides a solid scientific basis for considering that the problem of thermal expansion mismatch is not an issue for this type of stone under any possible conditions of natural exposure.

Current strategies of allergen-specific immunotherapy

The article discusses the principles of the optimal allergovaccine choice for allergen-specific immunotherapy (ASIT) for grass-pollen-allergy patients; reviewed efficacy and safety studies of the standardized mixt five-grass-pollen extract. Relatively grass sensitization is preferred use mixt grass-pollen extract is thus more suitable for specific immunotherapy, as it contains a broader repertoire of the epitopes, which approximate to the natural exposure conditions.