Environmental Exposure Conditions Research Articles

A review of developments in cathodic protection systems for reinforced concrete structures

Cathodic protection is a corrosion management strategy for deteriorating reinforced concrete structures or it can be used as preventative measure in situations where corrosion may be expected during the service life as a result of the environmental exposure conditions. The technology has advanced over time. There are now a number of different systems that can conveniently be considered in three categories, including impressed current cathodic protection (ICCP), hybrid cathodic protection (HCP), and galvanic cathodic protection (GCP). Asset owners need to choose which option to use possibly without understanding the different sustainability, environmental, health and safety, construction, technical, operational, and monitoring aspects. Generally, it is agreed among corrosion engineers that ICCP is the most powerful and robust solution for corrosion management in structures with widespread deterioration. HCP and GCP can also be viable options, even in the most aggressive environments with future maintenance intervention. The advantages and disadvantages of each system are discussed in detail. This paper also explains why the commonly accepted life expectancy of ICCP systems is 50 to 75 years compared to HCP and GCP, which are typically limited to 15-30 years. The details of the likely maintenance requirements, associated timescales, and whole-life costs for a 100-year design life are analysed with references to sustainability. That includes a discussion about the corrosion management system that presents the lowest embodied carbon option for different environments.

Impact of Environmental Exposure on the Service Life of Façade Claddings—A Statistical Analysis

Façade claddings, as the outer protection layer of the building’s envelope, are directly exposed to environmental degradation agents. The façades’ orientation and their distance from the sea, among other location and protection-related factors, influence their vulnerability to climate loads, in particular wind and air humidity. These loads, as well as exposure to air pollution, affect the degradation process of claddings and the durability of façades. Therefore, studying the impact of the environmental exposure conditions on the service life of different external claddings provides useful information on their performance over time, which can support (i) decision-makers in the selection of the best façade cladding solutions and (ii) further research on the impact of climate change on building components. This study covers six types of cladding: rendered façades (R), natural stone cladding (NSC), ceramic tiling system (CTS), painted surfaces (PS), external thermal insulation composite systems (ETICS), and architectural concrete façades (ACF). Three hundred façades located in Portugal are analysed according to three main groups of variables, which characterize (i) the façades, (ii) their degradation condition, and (iii) the environmental deterioration loads and context. The statistical analysis results reveal that the environmental variables affect the cladding degradation process. South-oriented façades present lower degradation conditions than façades facing north. The distance from the sea and high exposure to pollutants add to the degradation conditions, reducing the expected service life of façades. The results reveal that claddings can be organized according to two main groups: the most durable (CTS, NSC, and ACF) and the least durable (R, PS, and ETICS) systems. This study enables a comprehensive analysis of the data, useful to draw conclusions about the influence of environmental exposure conditions on the degradation and service life of façade claddings.

Transcriptomic Profile of the Cockle Cerastoderma edule Exposed to Seasonal Diarrhetic Shellfish Toxin Contamination.

Bivalves constitute an important source of proteins for human consumption, but some accumulate biotoxins such as diarrhetic shellfish toxins (DSTs), constituting a risk to human health. The cockle Cerastoderma edule is one of the most important species harvested in the Portuguese coast but also one of the most affected species due to recurrent DSTs exposure. However, little is known regarding the effects of the toxins produced by blooming dinoflagellates on C. edule. Herein, we explore the Differentially Expressed Genes (DEGs) of two tissues (gills and digestive gland) from wild cockles sampled in Portugal, through their whole transcriptomic response in two different seasons (exposed and not exposed to DSTs). The de novo transcriptome assembly returned 684,723 contigs, N50 of 1049, and 98.53% completeness. Altogether, 1098 DEGs were identified, of which 353 DEGs were exclusive for the digestive gland, 536 unique for the gills and 209 DEGs were common. Among DEGs were identified known DSTs-biomarkers including glutathione peroxidase, glutathione S-transferase, superoxide dismutase, cytochrome P450, ABC transporters, actin and tubulin-related proteins, Heat shock proteins and complement C1Q-like proteins. This study provides the first transcriptomic profile of C. edule, giving new insights about its molecular responses under different environmental conditions of DSTs exposure.

Effect of Hybrid Fibres on the Durability Characteristics of Ternary Blend Geopolymer Concrete

The need to develop sustainable concrete in the civil infrastructure industry increases day by day, resulting in new eco-friendly materials such as geopolymer concrete. Geopolymer concrete is one of the eminent alternatives to conventional concrete for sustainable development by reducing the carbon footprint. Ternary blend geopolymer concrete (TGPC) is a sustainable and environmentally friendly concrete produced with three different source materials to form a binder. The main advantage of TGPC is that it possesses densely packed particles of different shapes and sizes, which results in improved properties. This paper deals with the experimental investigations to evaluate the durability properties of plain and hybrid fibre reinforced TGPC. The durability of concrete is defined as the ability to withstand a safe level of serviceability and different environmental exposure conditions without any significant repair and rehabilitation throughout the service life. Conventional concrete is vulnerable to cracking due to its low tensile and durability properties. The TGPC considered in this work consists of fly ash, GGBS and metakaolin as source materials, selected mainly based on the material’s silica and alumina content, shape, size, and availability. The grade of concrete considered was M55. The main variables considered in this study were the proportions of crimped steel fibres (Vf), viz., 0.5% and 1% and proportions of polypropylene fibres (Vp)viz., 0.1%, 0.15%, 0.20% and 0.25%. The durability properties like water absorption, sorptivity, resistance to marine attack, acid attack, sulphate attack, and abrasion were studied in this investigation. The experimental test results were compared with the requirements provided in the standard/literature and found to be well within limits. The study also indicates that the inclusion of fibres in a hybrid form significantly improves the durability parameters of TGPC. The TGPC with 1% steel fibre and 0.15% polypropylene fibre performs better than the other combination of fibres considered in this experimental investigation.

Degradation Assessment of Natural Stone Claddings over Their Service Life: Comparison between Tehran (Iran) and Lisbon (Portugal)

Now more than ever, the construction sector is aiming to adopt more sustainable solutions. To achieve this purpose, more durable solutions must be adopted, making rational decisions at the design and maintenance stages regarding the conditions of environmental exposure and use. In this sense, knowledge regarding the service life of building components is crucial. This knowledge should not be a general concept, or a standard value, and adapting practices from one country to another is extremely challenging. In this sense, this study analyses the service life of natural stone claddings. We adopt a methodology initially proposed for Lisbon (Portugal), intending to evaluate its applicability to other geographical contexts, in order to perform a more reliable service life prediction of stone claddings located in Tehran (Iran). An estimated service life of 65 years was obtained for a sample of 162 stone claddings directly adhered to the substrate, located in Tehran, which were analysed by in situ inspections. The impact of different conditions (e.g., type of stone and environmental exposure conditions) on the service life of stone claddings in Tehran was quantified, which revealed that the exposure to environmental agents, such as wind, rain and pollutants, is the main cause of degradation of the natural stone claddings.

Relation between durability and mechanical properties on glass fiber reinforced slag-based geopolymer

This work seeks to improve the understanding of the durability of pure slag-based geopolymer composites containing glass fibers. Degradation by attack of saline mist, simulated by the salt-spray essay, was carried out for a period of 30 days. The test simulates the conditions found in the sea and nearby environments. The chamber works at relative humidity ∼97%, by nebulizing sodium chloride solutions with a concentration of 5% at 35 + 2 °C, solution pH between 6.5 and 7.2. After the cycle, the loss of mass and the compressive strength of the specimens were measured. The efflorescence formation in slag-based geopolymers is also assessed in this study to provide a better understanding of the effect of the synthesis parameters. It is noted that physical and chemical properties of geopolymers, and environmental exposure conditions can affect the rate of efflorescence formation. Besides the control set group, two different solutions to prevent efflorescence were tested, MgO and an efflorescence reduction agent from Sika®. The work aims to examine the effect of efflorescence formation on mechanical properties, through flexural and compressive strengths. A compromise between durability and mechanical properties was found for specimens enriched with 2% of efflorescence reduction agent.

Durability performance of reinforced waste-based geopolymer foam concrete under exposure to various corrosive environments

The construction of conventional concrete structures produces a significant quantity of CO2 released into the environment which can directly impact human health and contribute to global warming. Geopolymer foam concrete is a low carbon eco-friendly concrete in which CO2 releasing cement is replaced with industrial waste materials. However, the durability of geopolymer foam concrete under needs to be investigated over a range of corrosive environments to enable application as a construction material. Therefore, determining the influence of these corrosive factors on the reinforcing steel in geopolymer foam concrete is the objective of the current research. A detailed multi-variable experimental programme was conducted, and models were derived to quantifying the factors influencing the corrosion and mechanical behaviour of reinforced geopolymer foam concrete (RGFC) under exposure to varying chloride, temperature and humidity. Specimens were cast with three chloride percentages, i.e., 1%, 3% and 5% for accelerated corrosion, and exposed to temperatures of 35 and 24 Celsius, and humidity levels of 50% and 90%, respectively. Gravimetric weight loss measurements of the corroded reinforcing steel were undertaken at three designated time intervals. Following corrosion monitoring, the corroded reinforcing steel was tested under tension to observe the influence of the environmental exposure on their mechanical properties, specifically ductility and strength. Utilizing the test results, analytical expression and Multilayer Perception (MLP) neural network computations were executed to accurately quantify the influence of the various environmental exposure conditions on corrosion in RGFC. The findings of the modelling suggested temperature as the most dominant factor in inducing corrosion followed by humidity. Furthermore, the relationships for the prediction of loss of ductility and tensile strength of the reinforcing steel in RGFC as the function of chloride, temperature and humidity were derived. Finally, to conclude, the outcomes of the current research enhance the knowledge on the durability of GFC as a construction material and practically contribute to its service life determination.

Assessment of creep rupture and long-term performance of GFRP bars subjected to different environmental exposure conditions under high sustained loads

This paper presents an experimental investigation and statistical approach to assess the long-term performance and to determine a safe creep-rupture strength value for glass fiber-reinforced polymer (GFRP) bars subjected to different types of environmental exposure. The study sample consisted of 160 bars of various sizes (10 mm, 12 mm, and two types of 15 mm) subjected to different levels of environmental conditioning (unconditioned and exposed to an alkaline solution at 23 °C and 60 °C) and a range of sustained load levels (40% to 90% of the ultimate tensile strength). The test results were analyzed with Weibull statistical analysis to determine the mean and characteristic creep-rupture strengths, and consequently, a safe design value was calculated. Limitations and variations of the strength degradation model for the life-span prediction are discussed. The impact of sustained load on strength reduction was more pronounced than the combined effect of the alkaline solution and high temperature. The GFRP bars with smaller diameters were more susceptible to creep rupture than the larger ones, while the conditioning had more effect on the bars with larger diameters than the smaller ones. The creep-rupture reduction factors prescribed in current design codes are conservative for the GFRP bars in this study.

Field-scale performance of biochar-amended soil covers for landfill methane oxidation

A field validation of three biochar-amended soil covers (2%, 10%, and 100% biochar-amended soils) along with a soil control cover was conducted within the intermediate cover of an active municipal solid waste (MSW) landfill in conjunction with laboratory studies evaluating the effect of biochar in enhancing methane (CH4) oxidation in cover soils. Baseline CH4 emissions and pre-existing site conditions were characterized prior to installation of test plots simulating three cover designs evaluated in related laboratory studies. Static chamber measurements of surface CH4 fluxes and sampling of soil pore gas at different depths were conducted across the 8-month monitoring period to assess cover performance. Surface fluxes from the test plots exhibited wide spatial variability, with one location emitting fluxes > 1100 g CH4 m−2 day−1 in one survey. Potential rates of CH4 oxidation were determined in batch assays of exhumed soil core subsamples following termination of the field trial and ranged from ~1 to 350 μg CH4 g−1 day−1. The heterogeneity of the waste led to nonuniform CH4 loads in the test plots. The soil control test plot was exposed to higher CH4 loads and biochar-amended test plots were exposed to significantly lower CH4 loads. As a result, the soil control test plot showed higher CH4 oxidation rates (257–289 μg CH4 g−1 day−1) than the biochar-amended test plots. Similarly, the soil control plot also showed higher relative abundance of methanotrophs which was positively correlated with the CH4 oxidation rates. The test plot with 10% biochar-amended soil experienced CH4 loads nearly 25% of that in soil control and still showed CH4 oxidation rates (260 μg CH4 g−1 day−1) comparable to that of soil control which showed the efficacy of biochar amendment in enhancing CH4 oxidation rates. The environmental and CH4 exposure conditions affected the microbial community composition in the test plots and showed the dominance of type I methanotrophic genus such as Methylomonas and Crenothrix spp. Overall, the waste heterogeneity led to nonuniform CH4 exposure conditions at each test plot making it hard to distinctly quantify the effect of biochar amendment on CH4 oxidation rates.

Impact of Environmental Exposure Conditions on the Maintenance of Facades’ Claddings

Façades, as the most external building envelope component, are subject to different ex-ternal environmental loads, such as: Temperature, precipitation, damp, and wind. Therefore, the contribution of environmental actions to the occurrence of defects in façades claddings is an important subject of study since these actions strongly affect the degradation process and natural ageing of these components during their service life. In this study, a methodology to support decision-makers in the process of selecting a façade cladding system and the maintenance strategy to implement is presented and discussed. This methodology covers the performance of four façade claddings (ceramic tiling systems (CTS), natural stone claddings (NSC), external thermal insulation composite systems (ETICS), and architectural concrete façades (ACF)) over time, according to three environmental exposure variables (exposure to damp, distance from the sea, and orientation). The databases were established based on the diagnosis of the degradation condition of these claddings in-service conditions, in Portugal. The results reveal that the environmental exposure variables have a significant impact on maintenance requirements and costs. For all the categories of the environmental exposure condition variables, under all scenarios, ETICS is the least favorable constructive solution while CTS is the most advantageous solution. Furthermore, the results show that properly implemented maintenance activities enhance the performance level of building components, which positively affects their degradation behavior over time.

Monitoring Environmental and Climatic Exposure Conditions for Structures in Cold Regions

Abstract The durability of structures is greatly affected by their level of exposure to environmental and climatic conditions. In the case of northern structures, a major factor of deterioration is...

Comparison of the design of prestressed concrete hollow-core floor units with Eurocode 2 and ACI 318

A typical 1200 mm (48 in.) wide × 200 mm (8 in.) deep prestressed concrete hollow-core unit is analyzed and designed in order to make a comparison between Eurocode 2 and ACI 318-08. This includes calculations for serviceability limit state of stress and moment of resistance, ultimate moment of resistance, ultimate shear capacities, flexural stiffness (that is, for deflection), and cover to pretensioning tendons for conditions of environmental exposure and fire resistance. Concrete cylinder strength is 40 MPa (5.8 ksi), and concrete cube strength is 50 MPa (7.3 ksi). The hollow-core unit is pretensioned using seven-wire helical strands. Worked examples are presented in parallel formation according to Eurocode 2 and ACI 318. For uniformly distributed loads, the design criterion between the service moment to service moment of resistance (Ms/Msr for EC2 and Ms/Msn for ACI 318) and the ultimate design bending moment to ultimate moment of resistance (MEd/MRd for EC2 and Mu/φMn for ACI 318) is well balanced for this example. Usually the service moment is critical unless the amount of prestress is small. For EC2-1-1, flexurally uncracked shear capacity VRd,c is only limiting when the span-to-depth ratio in this example is less than about 35. For ACI 318, flexurally cracked shear capacity φVci is limiting when span-to-depth ratio is 42, showing that shear cracked in flexure will often be the governing criterion.

Challenges in quantification of photocatalytic NO2 abatement effectiveness under real world exposure conditions illustrated by a case study

Health risks due to NO2 exposure commonly exceed acceptable levels in modern societies. Among the measures to reduce such risks, photocatalytic materials present a promising technology. However, while the pollutant remediation of such materials has been extensively validated in laboratory studies, the performance under real world environmental exposure conditions is still subject to controversy. Indeed, a comparison of available in-situ monitoring studies manifests non-conclusive and highly scattered results regarding the photocatalytic effectiveness observed. The reasons for this behaviour must be carefully explored in order to prevent non-efficient photocatalytic applications from being put into practice on a larger scale. This paper presents a comprehensive large-scale study for assessing the photocatalytic NO2 remediation by active pavements in a street of Madrid (Spain), comprising different in-situ monitoring techniques. The discussion is enriched by relating the obtained results to those of other large-scale studies. The discrepancies between these results may be traced back to different circumstances, among them the distance between the active pavement and the pollutant concentration sampling inlet, as well as to significant site-specific and time-dependent variations of pollutant concentrations and climatic parameters. Under due consideration of these influences, for materials with relatively high initial effectiveness, it was concluded that in most such applications, the average NO2 removal effectiveness, if evaluated at a typical inlet height of Air Quality Stations (3 m), will not exceed a value of 4% (averaged over a sufficiently large number of measurement points in the area of application and a sustained amount of time, i.e. several months). When considering more realistic human exposure conditions (lower heights and daytime), it might be justified to assume somewhat higher average effectiveness.

In-Situ Raman Analysis of Precipitates Formed By Cathodic Polarization for Study of Atmospheric Corrosion in Marine Relevant Environments

Dry storage of spent nuclear fuel (SNF) in the United States exists across the country at independent fuel storage installations sites. At these sites the SNF is stored in stainless steel (SS) canisters equipped with a concrete overpack, where airflow through inlet and outlet vents allow for the passive cooling of the payload. While SS canisters are known for their enhanced corrosion resistance, when placed in a marine and near-marine environment they have shown to be suspectable to localized corrosion. In these environments, sea salt aerosols can adhere to the SS surface and, under certain temperature and relative humidity ranges, deliquescence can occur to form chloride rich brines. Under such exposure conditions, SS is known to undergo passive breakdown and pitting corrosion; thus, can be susceptible to subsequent stress corrosion cracking in the presence of residual stresses.In this study, we explore the relationship between the cathodic polarization and the surface brine present on 304-SS. Corrosion and pitting are a function of both the anodic current demand and the available cathodic current both of which have been shown to be dependent on the environmental exposure conditions. In concentrated salt solutions, certain bulk cations (Mg2+) have a strong thermodynamic driving force to form stable precipitates, such as hydroxides, driven by an increase in pH at the cathode from corrosion reactions, which can block cathodic reduction sites. Using in-situ Raman measurements during a cathodic polarization scan we attempted to identify under which conditions (e.g., potential, pH) precipitates form and what their overall composition is. In MgCl2 rich brines, we observed that the pH of precipitation and the identity of the precipitate were dependent upon the initial MgCl2 concentration, as predicted by thermodynamic modeling. The implications of these measurements demonstrate that the maximum pit size in MgCl2 brine surface environments may be limited as the cathodic reduction sites are blocked by precipitation, perhaps leading to the starvation of the pit and eventual brine dry out.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. Figure 1. In-situ Raman of SS in 0.189 M MgCl2 brine showing the formation of microcrystalline brucite. Figure 1

Hormetic dose-dependent response about typical antibiotics and their mixtures on plasmid conjugative transfer of Escherichia coli and its relationship with toxic effects on growth

Bacterial resistance caused by the abuse of antibiotics has attracted worldwide attention. However, there are few studies exploring bacterial resistance under the environmental exposure condition of antibiotics that is featured by low-dose and mixture. In this study, sulfonamides (SAs), sulfonamide potentiators (SAPs) and tetracyclines (TCs) were used to determine the effects of antibiotics on plasmid RP4 conjugative transfer of Escherichia coli (E. coli) under single or combined exposure, and the relationship between the effects of antibiotics on conjugative transfer and growth was investigated. The results show that the effects of single or binary antibiotics on plasmid RP4 conjugative transfer all exhibit a hormetic phenomenon. The linear regression reveals that the concentrations of the three antibiotics promoting conjugative transfer are correlated with the concentrations promoting growth and the physicochemical properties of the compounds. The combined effects of SAs-SAPs and SAs-TCs on plasmid conjugative transfer are mainly synergistic and antagonistic. While SAPs provide more effective concentrations for the promotion of conjugative transfer in SAs-SAPs mixtures, SAs play a more important role in promoting conjugative transfer in SAs-TCs mixtures. Mechanism explanation shows that SAs, SAPs and TCs inhibit bacterial growth by acting on their target proteins DHPS, DHFR and 30S ribosomal subunit, respectively. This study indicates that toxic stress stimulates the occurrence of conjugative transfer and promotes the development of bacterial resistance, which will provide a reference for resistance risk assessment of antibiotic exposure.

From analysis to decision: Revision of a multifactorial model for the in situ assessment of NOx abatement effectiveness of photocatalytic pavements

The analysis of NOx abatement of photocatalytic construction materials under outdoor exposure still presents important challenges. Statistical models are a necessary tool to account for the large uncertainties involved in such complex, multifactorial processes, especially if employed in the context of decision problems confronting local authorities and other stakeholders in everyday practice.On this background, the paper reports on the revision of a preliminary multiple linear regression model for the comparative study of NOx removal behavior of urban pavement materials. The model is based on in-situ measurements at pilot plant scale, performed on nine different of such materials. Important advances of the model development include the significant enhancement of its statistical robustness and application boundaries regarding environmental exposure conditions or the materials analysed. The model identifies the material substrate humidity as a key variable and reveals the importance of Ti coating quality. Microscopic characterizations lean support to the model predictions.

Characterization of Bacteriophages against Pseudomonas Syringae pv. Actinidiae with Potential Use as Natural Antimicrobials in Kiwifruit Plants

Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of a bacterial canker in kiwifruit plants and has caused economic losses worldwide. Currently, the primary strategies to control this pathogen include the use of copper-based compounds and even antibiotics. However, the emergence of isolates of Psa that are resistant to these agrochemicals has raised the need for new alternatives to control this pathogen. Bacteriophages have been proposed as an alternative to control bacterial infections in agriculture, including Psa. Here, we show the isolation and characterization of 13 phages with the potential to control Psa infections in kiwifruit plants. The phages were characterized according to their host range and restriction fragment length polymorphism (RFLP) pattern. Four phages were selected according to their lytic effect on the bacteria and their tolerance to different environmental conditions of pH (4–7), temperature (4–37 °C), and solar radiation exposure (30 and 60 min). The selected phages (CHF1, CHF7, CHF19, and CHF21) were sequenced, revealing a high identity with the podophage of Psa phiPSA2. In vitro assays with kiwifruit leaf samples demonstrated that the mixture of phages reduced the Psa bacterial load within three hours post-application and was able to reduce the damage index in 50% of cases. Similarly, assays with kiwifruit plants maintained in greenhouse conditions showed that these phages were able to reduce the Psa bacterial load in more than 50% of cases and produced a significant decrease in the damage index of treated plants after 30 days. Finally, none of the selected phages were able to infect the other bacteria present in the natural microbiota of kiwifruit plants. These results show that bacteriophages are an attractive alternative to control Psa infections in kiwifruit plants.

Developing ‘Smart’ Solutions for Light Management for Historic Collections

ABSTRACT In 2011 Historic Royal Palaces began to investigate protective measures for historic tapestries on open display at Hampton Court Palace. The environmental exposure conditions for each tapestry were analysed and mapped to evaluate risk. An innovative method to reduce illuminance and direct sunlight on the historic tapestries using ‘smart’ technologies was developed. The design, testing and implementation of the installation of Smart Tint liquid crystal films whose optical appearance can be switched electrically from opaque to transparent, are presented. Substantial reduction (>90%) in direct light transmission could be achieved when the film is opaque. It also provides additional protection from ultraviolet (99%) and infrared radiation (98%). An entirely reversible and customised installation method had to be devised using pressure-fixed lightweight aluminium frames. An automated controller was also installed to change the individual windows from clear to opaque during different times of the day depending on their orientation and the time of the year while a dedicated wireless mesh network system enabled communication between each window and the controller. The impact of this installation is described. The use of ‘smart’ technologies offered dynamic light protection for collections on open display while maintaining the presentation of the historic room. The benefits of adopting this innovative technology include its flexible and unobtrusive installation.

Mechanism of Acrolein Toxicity:The Effect on Epigenetic Changes

Acrolein, an alpha‐beta unsaturated aldehyde and a very reactive toxic compound, is released into the environment from different sources such as combustion of fossil fuel, cigarette smoke, overheating of frying oil, as well as endogenously being produced in body via lipid peroxidation. As a pervasive environmental pollutant, acrolein poses a serious environmental health threat acknowledged by investigators, health, and environmental government agencies.Epigenetics is the modifications in gene expression that do not alter the DNA sequence of a gene. This alteration could occur naturally or by factors such as age, environmental exposure, individual lifestyle, and disease condition. Phosphorylation, Methylations and acetylation are the most common epigenetic changes. N‐ Acetyl cysteine (NAC) is an antioxidant involved in the production of cellular glutathione.The aim of the study was to determine the effect of acrolein on histone phosphorylation, acetylation and methylation in vascular smooth muscle cells (VSMCs) and to establish the beneficial effect of NAC in prevention of acrolein toxicity through blockage of histones modification.VSMCs were treated with 3μg/ml acrolein for 6 hours in the presence and absence of 0.2 mM NAC. At the end of the treatment, cytotoxicity of acrolein was measured using tetrazolium‐calorimetric assay. Additionally, free radical generation was measured by fluorometric methods, histone H3 modification by ELISA kit, and protein expression by western blotting.Results indicated that six‐hour exposure of VSMC to 3μg/ml of acrolein resulted in 99% decrease in cell viability and addition of 0.2Mm of NAC provided complete protection of VSMCs from toxicity caused by acrolein. In the absence of NAC, acrolein increased level of reactive oxygen species (ROS) generation by 85%. Addition of NAC abolished high level of ROS by 75%.ELISA analysis showed acrolein‐induced modification of histones 3 (H3) at different lysine and serine residues including SER‐10P and SER‐28P, K4ME, K9ME, K27ME, K79ME, K9AC, K14AC, K18AC. Western blot analysis of two of these residues indicated 45% increase in Ser10P1, 59% increase in Ser28p1, and addition of NAC decreased these modifications by 86% and 76% respectively. Additionally, we observed a 66% increase in the expression of methylated H3K9 and 66% in acetylated H3k9 protein, which was attenuated by addition of NAC by 71% and 65% respectively.In conclusion, this study revealed that exposure of VSMCs to acrolein causes modification of H3 histones at different residues and NAC is effective in inhibiting the effects of acrolein.Support or Funding InformationNIH SC3GM103746‐04

Effect of exposure conditions on dirt pickup resistance (DPR)

Discoloration over time is a common cause for dissatisfaction of exterior architectural (decor) paints in much of the world. As such, it is an area of active research interest for producers of these paints and their raw material suppliers. The rate of discoloration of any particular paint depends on the interplay between certain physical properties of that paint and the environmental exposure conditions. Such an interplay can be established by exposing a series of paints to a variety of real-world environmental conditions. In this paper, we report the dirt pickup resistance results for 26 commercial exterior paints exposed at four different locations and the results of a subsequent study of ten commercial paints at two exposure locations. Repeatability and reproducibility of these tests were determined by exposing the same two paints, with replicates, at different exposure sites and at different dates. We believe this is the first time such information has been reported. Within-series repeatability was good, but series-to-series reproducibility was poor, stressing the need to compare performance only among paints exposed at the same time and location. In addition to testing dirt pickup, we investigated the degree to which microbial growth can contribute to discoloration and found a strong correlation between mildew infestation and decrease in L* under conditions that favor mildew growth. Finally, we investigated the extent to which panel orientation affects the decrease in film brightness over time and found that change in L* was partially dependent on orientation, and that early results at 45° south-facing were accurate predictors of long-term results for vertical orientations for the paints tested.