Various Conditions Of Exposure Research Articles

Automated assessment of task-based performance of digital mammography and tomosynthesis systems using an anthropomorphic breast phantom and deep learning-based scoring.

Conventional metrics used for assessing digital mammography (DM) and digital breast tomosynthesis (DBT) image quality, including noise, spatial resolution, and detective quantum efficiency, do not necessarily predict how well the system will perform in a clinical task. A number of existing phantom-based methods have their own limitations, such as unrealistic uniform backgrounds, subjective scoring using humans, and regular signal patterns unrepresentative of common clinical findings. We attempted to address this problem with a realistic breast phantom with random hydroxyapatite microcalcifications and semi-automated deep learning-based image scoring. Our goal was to develop a methodology for objective task-based assessment of image quality for tomosynthesis and DM systems, which includes an anthropomorphic phantom, a detection task (microcalcification clusters), and automated performance evaluation using a convolutional neural network. Experimental 2D and pseudo-3D mammograms of an anthropomorphic inkjet-printed breast phantom with inserted microcalcification clusters were collected on clinical mammography systems to train a signal-present/signal-absent image classifier based on Resnet-18 architecture. In a separate validation study using simulations, this Resnet-18 classifier was shown to approach the performance of an ideal observer. Microcalcification detection performance was evaluated as a function of four dose levels using receiver operating characteristic (ROC) analysis [i.e., area under the ROC curve (AUC)]. To demonstrate the use of this evaluation approach for assessing different technologies, the method was applied to two different mammography systems, as well as to mammograms with re-binned pixels emulating a lower-resolution X-ray detector. Microcalcification detectability, as assessed by the deep learning classifier, was observed to vary with the exposure incident on the breast phantom for both DM and tomosynthesis. At full dose, experimental AUC was 0.96 (for DM) and 0.95 (for DBT), whereas at half dose, it dropped to 0.85 and 0.71, respectively. AUC performance on DM was significantly decreased with an effective larger pixel size obtained with re-binning. The task-based assessment approach also showed the superiority of a newer mammography system compared with an older system. An objective task-based methodology for assessing the image quality of mammography and tomosynthesis systems is proposed. Possible uses for this tool could be quality control, acceptance, and constancy testing, assessing the safety and effectiveness of new technology for regulatory submissions, and system optimization. The results from this study showed that the proposed evaluation method using a deep learning model observer can track differences in microcalcification signal detectability with varied exposure conditions.

Effects of water quality on palladium-induced olfactory toxicity and bioaccumulation in rainbow trout (Oncorhynchus mykiss).

Through emission processes, palladium (Pd) particulates from industrial sources are introduced into a range of ecosystems including freshwater environments. Despite this, research on Pd-induced bioaccumulation, uptake, and toxicity is limited for freshwater fishes. Unlike other metals, there are currently no regulations or protective guidelines to limit Pd release into aquatic systems, indicating a global absence of measures addressing its environmental impact. To assess the olfactory toxicity potential of Pd, the present study aimed to explore Pd accumulation in olfactory tissues, olfactory disruption, and oxidative stress in rainbow trout (Oncorhynchus mykiss) following waterborne Pd exposure. Olfactory sensitivity, measured by electro-olfactography, demonstrated that Pd inhibits multiple pathways of the olfactory system following 96 h of Pd exposure. In this study, the concentrations of Pd for inhibition of olfactory function by 20% (2.5 μg/L; IC20) and 50% (19 μg/L; IC50) were established. Rainbow trout were then exposed to IC20 and IC50 Pd concentrations in combination with varying exposure conditions, as changes in water quality alter the toxicity of metals. Independent to Pd, increased water hardness resulted in decreased olfactory perception owing to ion competition at the olfactory epithelium. No other environmental parameter in this study significantly influenced Pd-induced olfactory toxicity. Membrane-associated Pd was measured at the olfactory rosette and gill following exposure; however, this accumulation did not translate to oxidative stress as measured by the production of malondialdehyde. Our data suggest that Pd is toxic to rainbow trout via waterborne contamination near field-measured levels. This study further demonstrated Pd bioavailability and uptake at water-adjacent tissues, adding to our collective understanding of the toxicological profile of Pd. Taken together, our results provide novel insights into the olfactory toxicity in fish following Pd exposure. Integr Environ Assess Manag 2024;20:1407-1419. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Development and optimisation of in vitro sonodynamic therapy for glioblastoma

Sonodynamic therapy (SDT) is currently on critical path for glioblastoma therapeutics. SDT is a non-invasive approach utilising focused ultrasound to activate photosensitisers like 5-ALA to impede tumour growth. Unfortunately, the molecular mechanisms underlying the therapeutic functions of SDT remain enigmatic. This is primarily due to the lack of intricately optimised instrumentation capable of modulating SDT delivery to glioma cells in vitro. Consequently, very little information is available on the effects of SDT on glioma stem cells which are key drivers of gliomagenesis and recurrence. To address this, the current study has developed and validated an automated in vitro SDT system to allow the application and mapping of focused ultrasound fields under varied exposure conditions and setup configurations. The study optimizes ultrasound frequency, intensity, plate base material, thermal effect, and the integration of live cells. Indeed, in the presence of 5-ALA, focused ultrasound induces apoptotic cell death in primary patient-derived glioma cells with concurrent upregulation of intracellular reactive oxygen species. Intriguingly, primary glioma stem neurospheres also exhibit remarkably reduced 3D growth upon SDT exposure. Taken together, the study reports an in vitro system for SDT applications on tissue culture-based disease models to potentially benchmark the novel approach to the current standard-of-care.

Experimental Study Corrosion Parameters of Copper as an Eco-Friendly Heat Collector for Solar Water Heaters

The corrosion behaviour of copper as a solar collector material was adequately simulated in tests in a solar water heating system. The weight loss technique of corrosion determination was used under exposure conditions ranging from slightly acidic to alkaline. Uniform corrosion was observed and corrosion rates; calculated estimates of the life of a typical collector made of copper were evaluated and found to be below 0.0254 mmpy and the subsequent evaluation of the life of a 3mm thick pipe shows lives of over a hundred years under the varying exposure conditions. A significant fact is that uniform corrosion took place over the period of the test.

Accumulation and Speciation of Cobalt in Paracentrotus lividus.

Since the first human release of radionuclides on Earth at the end of the Second World War, impact assessments have been implemented. Radionuclides are now ubiquitous, and the impact of local accidental release on human activities, although of low probability, is of tremendous social and economic consequences. Although radionuclide inventories (at various scales) are essential as input data for impact assessment, crucial information on physicochemical speciation is lacking. Among the metallic radionuclides of interest, cobalt-60 is one of the most important activation products generated in the nuclear industry. In this work, a marine model ecosystem has been defined because seawater and more generally marine ecosystems are final receptacles of metal pollution. A multistep approach from quantitative uptake to understanding of the accumulation mechanism has been implemented with the sea urchin Paracentrotus lividus. In a well-controlled aquarium, the day-by-day uptake of cobalt and its quantification in different compartments of the sea urchin were monitored with various conditions of exposure by combining ICP-OES analysis and γ spectrometry. Cobalt is mainly distributed following the rating intestinal tract ≫ gonads > shell spines. Cobalt speciation in seawater and inside the gonads and the intestinal tract was determined using extended X-ray absorption fine structure (EXAFS). The cobalt inside the gonads and the intestinal tract is mainly complexed by the toposome, the main protein in the sea urchin P. lividus. Complexation with purified toposome was characterized and a complexation site combining EXAFS and AIMD (ab initio molecular dynamics) was proposed implying monodentate carboxylates.

Acute Adverse Effects of Metallic Nanomaterials on Cardiac and Behavioral Changes in Daphnia magna

Nanomaterials are widely believed to induce toxic effects on organisms by evoking oxidative stress. We evaluated the toxic effects of nanomaterials on the cardiac and behavioral changes in Daphnia magna under varying exposure conditions. Titanium dioxide nanoparticles (TiO2 NPs), silver nanoparticles (AgNPs), and silver nitrate (AgNO3) were selected for the acute toxicity tests. The adverse effects of the substances on the neonates including heart rate, swimming speed, and oxidative stress were measured. The heart rate level decreased as the concentration of both NPs and silver ions (Ag+) increased. The average swimming speed was measured to be approximately 15 mm/min for the control group. The swimming speed generally increased with a longer exposure to both NPs although it reached a plateau at the lowest concentration of AgNPs. A similar but less clear trend was observed for Ag+. For all substances, the overall swimming speed exhibited no correlation or weak negative correlations with the exposure concentration. The oxidative stress levels increased after exposure compared with the control group. We conclude that aquatic nanotoxicity tests should consider multilevel physicochemical, physiological, and behavioral parameters for the official guidelines to quantify more robust adverse outcomes.

Studies on the Ageing of Cement Stabilized Rammed Earth Material in Different Exposure Conditions.

This paper aims to test the deterioration of cement stabilized rammed earth and consider its characteristics during its lifespan in various exposure conditions. Both visual and mechanical properties were tested to determine the impact of long-term exposure to natural weather conditions. Cemented stabilized rammed earth is a variation of the traditional rammed earth building material which has been used since ancient history and is strengthened by the addition of stabilizers in the form of Portland cement. This article analyzes the long-term properties of wall panels made of this material, which were subjected to varying exposure conditions for five years. After this period, compression tests of specimens cut from panels stored in various environmental conditions were carried out. Based on the results and visual properties of the specimens, long-term changes in unconfined compressive strength were observed and primary durability attributes were described. Despite minimal visible wear to the external layers of the wall panels, the natural weather conditions proved to deteriorate material strength characteristics, especially on specimens with high cement content. No correlation between visual characteristics and compressive strength measures were found. The present study is vital in adequately describing cement stabilized rammed earth behavior in natural weather conditions typical of a humid continental climate.

Automated image analysis to assess hygienic behaviour of honeybees.

Focus of this study is to design an automated image processing pipeline for handling uncontrolled acquisition conditions of images acquired in the field. The pipeline has been tested on the automated identification and count of uncapped brood cells in honeybee (Apis Mellifera) comb images to reduce the workload of beekeepers during the study of the hygienic behavior of honeybee colonies. The images used to develop and test the model were acquired by beekeepers on different days and hours in summer 2020 and under uncontrolled conditions. This resulted in images differing for background noise, illumination, color, comb tilts, scaling, and comb sizes. All the available 127 images were manually cropped to approximately include the comb area. To obtain an unbiased evaluation, the cropped images were randomly split into a training image set (50 images), which was used to develop and tune the proposed model, and a test image set (77 images), which was solely used to test the model. To reduce the effects of varied illuminations or exposures, three image enhancement algorithms were tested and compared followed by the Hough Transform, which allowed identifying individual cells to be automatically counted. All the algorithm parameters were automatically chosen on the training set by grid search. When applied to the 77 test images the model obtained a correlation of 0.819 between the automated counts and the experts' counts. To provide an assessment of our model with publicly available images acquired by a different equipment and under different acquisition conditions, we randomly extracted 100 images from a comb image dataset made available by a recent literature work. Though it has been acquired under controlled exposure, the images in this new set have varied illuminations; anyhow, our pipeline obtains a correlation between automatic and manual counts equal to 0.997. In conclusion, our tests on the automatic count of uncapped honey bee comb cells acquired in the field and on images extracted from a publicly available dataset suggest that the hereby generated pipeline successfully handles varied noise artifacts, illumination, and exposure conditions, therefore allowing to generalize our method to different acquisition settings. Results further improve when the acquisition conditions are controlled.

Detection of Reactive Oxygen Species in Human Neutrophils Under Various Conditions of Exposure to Galectin.

Reactive oxygen species (ROS) have been extensively studied in biology in the past years. This class of molecules can be derived from endogenous sources (e.g., phagocytic cells as neutrophils, eosinophils, monocytes, macrophages, and organelles as mitochondria and peroxisomes) and participate in physiological and pathological conditions. The beneficial and harmful effects of ROS depend on redox regulation, which establishes the balance between their production and the activity of antioxidant systems to prevent oxidative stress in vivo. Neutrophils are the immune effectors most well depicted with an intense oxidative burst in response to tissue inflammation. Several proteins and members of the galectin family are involved in this fine modulation of ROS production by neutrophils. Interestingly, studies have indicated that Galectin-1 (Gal-1) can up- or downregulate ROS production by neutrophils even when exposed to N-formyl-Met-Leu-Phe (fMLP) or Phorbol Myristate Acetate (PMA), both of which are potent neutrophil stimulants that trigger high levels of ROS production. Similarly, Galectin-3 (Gal-3) induces ROS in neutrophils from a sterile or nonsterile inflammatory environment, possibly creating a negative loop that could control ROS production. Besides, superoxide production is also induced by Galectin-8 (Gal-8) and Galectin-9 (Gal-9) in neutrophils but in a different manner. We describe herein the luminol and lucigenin-dependent chemiluminescence technique by using a luminometer as a method of assessment to measure ROS production by human neutrophils isolated and exposed to purified human recombinant Gal-1. The protocol described herein could be applied for the investigation of the role of other galectins in the modulation of ROS production by neutrophils.

Modeling Time-varying Reliability and Resilience of Deteriorating Infrastructure

The spatial and temporal extent of disruptions to services provided by infrastructure following disruptive events is directly related to the instantaneous state of the infrastructure and their post-disruption recovery. This paper develops a novel formulation to model the effects of infrastructure deterioration on their time-varying ability to recover after disruptive events. By unifying available models for deterioration and recovery, the paper proposes a general formulation to model the physical state and functionality of deteriorating infrastructure throughout its service life. The paper further develops resilience measures to quantify the temporal and spatial variations of infrastructure's ability to recover after disruptive events. The proposed formulation has a hierarchical structure that enables exploiting readily available data at the lower level of hierarchy to improve the prediction capability of models at the infrastructure level. Incorporating the governing physical laws in the proposed formulation also enables customizing the models to emulate the reality of infrastructure deterioration and recovery. While the formulation is general, the emphasis is on modeling potable water infrastructure as a case in which the deterioration of pipelines grows mostly undetectable until extensively developed. By the time the deterioration becomes visible, a substantial portion of the infrastructure service life has already been depleted, and costly repair or replacement would be inevitable. To illustrate, the proposed formulation has been implemented to model the time-varying reliability and resilience of the potable water infrastructure of the city of Seaside in Oregon, United States. The example highlights the effects of spatially varying exposure conditions and pipelines’ age on the reliability, functionality, recovery, and resilience of the potable water infrastructure.

Diffusions of sound frequencies designed to target dehydrins induce hydric stress tolerance in Pisum sativum seedings

Among plant responses to environmentally induced stress modulating protein expression appears to be a key stage in inducible signaling. Our study was focused on an innovative strategy to stimulate plant stress resistance, namely, the use of targeted sequences of specific sound frequencies.The influence of acoustic stimulation on plant protein synthesis was investigated. In our study green peas, Pisum sativum, were cultured under hydric stress conditions with targeted acoustic stimulation. Acoustic sequences targeting dehydrins (DHN) which accumulate in plants in response to dehydration were studied. We experimented on pea seeding with two different sequences of sounds: the first one corresponded to DHN cognate protein and the second one was aimed at the DHN consensus sequence. Shoot elongation after pea seed germination was estimated by fresh weight gain studied in the presence of various conditions of exposure to both sequences of sounds. DHN expression in peas was quantified via ELISA tests and Western-blotting by using specific antibodies.A significant increase in fresh weight in peas grown under exposure to the DHN cognate sound sequence was observed, whereas the consensus sound sequence had no effect on growth. Moreover, the 37kDa DHN amount was increased in peas treated with the consensus acoustic sequence. These results suggest that the expression of DHN could be specifically modulated by a designed acoustic stimulus.

Estimating environmental exposure of cyclists in Cork using limited sensing capabilities

This paper presents a study on individual exposure of cyclists in Cork, Republic of Ireland, to air and sound pollution, along with vibration from cycling using relatively simple sensors. Cork is currently experiencing an increasing interest in cycling, and different types of cycling transects were covered in this regard with varied infrastructure and exposure conditions for air pollution, sound and vibration. Audio-visual records were maintained throughout this cycling campaign and to connect exposure observations with available infrastructure and traffic conditions. The study highlights how the variations of exposure conditions can be obtained with relatively easy instrumentation and how such observations can be related to decisions around cycling infrastructure even when the measurements are not of the highest standard and/or are sometimes missing. The method, observations and conclusions are relevant for understanding how low-cost, lower-quality sensors can still be relevant for assessing exposure conditions for cyclists.

Evaluation of carbonation depth evolution tendencies of reinforced concrete buildings located in coastal and inland areas of north cyprus

Carbonation is a critical concrete durability problem that is known to have potential adverse effects both on the concrete cover and steel reinforcing bars. This study involves detailed experimental investigations on the carbonation progress status of 149 samples from 39 existing buildings in North Cyprus that are located in coastal and inland areas. It is known that the varying exposure conditions in coastal and inland areas are likely to affect the durability performance of concrete buildings in different manners. Concrete core samples that were originally extracted from structures for compressive strength determination, were later tested by using Phenolphthalein indicator in order to determine the extent of carbonation occurred throughout their service duration. Besides studying their current carbonation states, the expected carbonation depth at the end of a 50-years of service life, as well as time needed to carbonate 30 mm-depth concrete cover were also investigated by using the Fick’s law. Results showed that 41% of the inland samples have been exhibiting satisfactory carbonation resistance performance according to Eurocodes, where this rate was as high as 71% for the samples obtained from coastal areas of North Cyprus.

ПОВЫШЕНИЕ КАЧЕСТВА ПРОПИТКИ ДРЕВЕСИНЫ БЕРЕЗЫ РАЗЛИЧНЫМИ СПОСОБАМИ

Wood is widely used for the production of sleepers in Russia. Sleepers made of natural wood have the disadvantage – short service life. It is possible to increase the service life of wooden sleepers using pressed (modified) wood for their manufacture. Wood pressing is one of the most promising areas for improving its physical and mechanical properties. Pressed wood, in its turn, has a drawback – the ability to significantly change size and shape when humidity changes, as well as low biological resistance. The solution to this problem is to impregnate wood with an antiseptic solution with a stabilizer. The durability of pressed wood products largely depends on the quality of its impregnation and the amount of absorbed solution by the surface layer. The most simple and effective method (among the known for impregnation in the manufacture of railway sleepers) is impregnation of wood in hot-cold baths. In the work, the efficiency of wood impregnation by the method of hot-cold baths has been studied taking into account various conditions of exposure to a cold solution. The first option is to quickly replace a hot solution with a cold one. The second is the impregnation of wood during the natural cooling of hot solution. It was found that the depth of wood impregnation during gradual cooling of wood in a hot solution is 2.5 times less than the depth of impregnation during cooling in a cold solution, both in the longitudinal and transverse directions. The amount of solution absorbed by wood when impregnated by the hot-cold bath method with the gradual cooling of hot impregnating solution is 16% less than when cooling in a cold impregnating solution. Hot-cold bath method with cooling in a cold solution can be recommended for the manufacture of sleepers from modified wood

MULTI-CHAMBER MODEL AS AN INSTRUMENT FOR ANALYSIS OF THE TOXICOKINETIC ROLE OF SOLUBILITY OF ELEMENT OXIDE NANOPARTICLES AND PHAGOCYTIC REACTION TO THEIR DEPOSITION IN LUNGS IN CHRONIC INHALATION EXPOSURE

The paper retraces the development of a mechanistic multi-chamber model describing particle retention in lungs in chronic inhalation exposures. This model was first developed and experimentally tested for various conditions of exposure to polydisperse dusts of SiO 2 or TiO 2 , and later successfully used as a basis for analyzing patterns in the retention of nanoparticles (NP) having different chemical compositions (Fe 2 O 3 , SiO 2 , NiO). The most significant adaptation of this model for exposure to element oxide NPs was due to the need to take into account not only the physiological mechanisms of their elimination, but also their solubility « in vivo ». It has been found that the relative contribution of the latter might be different for nanoparticles of different nature and predominant in some cases. The modeling of NiO-NPs retention also suggests that damage to the physiological pulmonary clearance mechanisms by particularly toxic nanoparticles might result in lung toxicokinetics becoming nonlinear.

Method for Attaining Dimensionally Accurate Conditions for High-Resolution Three-Dimensional Printing Ceramic Composite Structures Using MicroCLIP Process.

Continuous liquid interface production (CLIP) utilizes projection ultraviolet (UV) light and oxygen inhibition to transform the sequential layered three-dimensional (3D) manufacturing into a continuous fabrication flow with tremendous improved fabrication speed and structure integrity. Incorporating ceramic particles to the photo-curable polymers allows for additive manufacturing of ceramic parts featuring sophisticated geometries, mitigating the difficulties associated with traditional manufacturing processes. The presence of ceramic particles within the ink, however, strongly scatters the incident UV light. In the high-resolution CLIP (microCLIP) process, the scattering effect can significantly alter the process characteristics, resulting in broadening of lateral feature dimensions alongside curing depth reduction. Varying exposure conditions to accommodate scattering additionally affects the oxygen deadzone thickness (DZ), which is dependent on power of incident light. This introduces a systematic defocusing error for large deadzone thickness to further complicate process control, such as the unwanted narrowing of part features. In this work, we developed a systematic framework for process optimization by balancing those effects via experimental characterization. We showed that the reported method can provide a set of optimal process parameters (UV power and stage speed) for high-resolution 3D fabrication in accommodating the distinct characteristics of given photo-curable ceramic ink. The method to optimize process parameter was validated experimentally via fabricating a gradient index Luneburg lens comprising densely packed woodpile building-blocks with a strut width of 100 μm and a layer thickness of 60 μm using microCLIP at dimensionally accurate exposure conditions.

Time spent looking at food during a delay of gratification task is positively associated with children's consumption at ad libitum laboratory meals

Greater ability to delay gratification for an immediate food reward may protect against the development of obesity. However, it is not known if the behaviors children exhibit during a delay of gratification task are related to overeating in other contexts. The purpose of this analysis was to assess the relationship between observed child coping strategies during a delay of gratification task and laboratory intake from ad libitum test-meals. The sample consisted of 40, 7–9 year old children (40% (N = 16 with overweight/obesity). Across 5 laboratory visits, children consumed 3 identical test-meals presented after varying exposure conditions (i.e., no exposure, exposure to food commercials, exposure to toy commercials). On the first visit, children were recorded during a delay of gratification task which was coded for three behavioral themes: looking at vs. away from food, talking vs. staying silent, and fidgeting vs. sitting still. Pearson correlations and multiple regressions were run to look at the relationships between coping strategies and test-meal intake. Time spent looking away from food was negatively associated with ad libitum food consumption at the meals. Conversely, greater time spent looking at food was positively associated with ad libitum food consumption. These relationships were independent of covariates likely to influence intake (e.g., sex, age, weight status, parent income) and were more robust following food rather than toy commercial exposure. Children who spent more time looking at food and less time looking away during a delay of gratification task may be vulnerable to overeating in other contexts. Upon replication in larger samples, these behaviors could serve as modifiable targets in the development of childhood obesity prevention programs.

Consequent stages of developing a multi-compartmental mechanistic model for chronically inhaled nanoparticles pulmonary retention.

The paper retraces the development of a mechanistic multicompartmental system model describing particle retention in lungs under chronic inhalation exposures. This model was first developed and experimentally tested for various conditions of exposure to polydisperse dusts of SiO2 or TiO2. Later on it was successfully used as a basis for analyzing patterns in the retention of nanoparticles having different chemical compositions (Fe2O3, SiO2, NiO). This is the first publication presenting the outcomes of modeling lung retention of nickel oxide nano-aerosols under chronic inhalation exposure. The most significant adaptation of the above-mentioned model to the conditions of exposure to metal-oxide nanoparticles is associated with the need to describe mathematically not only the physiological mechanisms of their elimination but also their solubilization "in vivo" bearing in mind that the relative contribution of the latter may be different for nanoparticles of different nature and predominant in some cases. Using nickel oxide as an example, it is suggested as well that damage to the physiological pulmonary clearance mechanisms by particularly toxic nanoparticles may result in lung toxicokinetics becoming nonlinear.

Seismic life-cycle cost analysis of ageing highway bridges under chloride exposure conditions: modelling and recommendations

Chloride-induced corrosion of highway bridges constitutes a critical form of environmental deterioration and may result in significant escalation of seismic life-cycle costs due to increased fragility during earthquake events. Most of existing literature tends to adopt simplistic uniform area loss assumptions in lieu of potentially complex, yet realistic and more detrimental, pitting corrosion models for seismic vulnerability analysis. Since the degree of deterioration depends on the severity and duration of exposure, there exists a need to investigate the influence of uniform vs. pitting corrosion assumption on seismic life-cycle costs for varied chloride exposure conditions. A case-study example of a highway bridge in Central and Southeastern US reveals consideration of pitting corrosion as critical for extreme exposures compared to relatively minor settings. Subsequently this study provides recommendations to aid bridge engineers and stakeholders to balance between computational cost and accuracy of results to aid prompt decisions on rehabilitation of ageing bridges in different exposure conditions. A framework is also included to compute seismic life-cycle costs from generic measures of corrosion, independent of assumed exposure scenario. This framework is particularly helpful for seismic loss assessment of highway bridges in chloride exposure zones with periodic field measurements to estimate the extent of structural deterioration.

Preliminary Investigation of Carbonation Problem Progress in Concrete buildings of North Cyprus

Carbonation process is regarded as one of the most critical durability problem in concrete. As a result of carbonation process, the pH level in concrete is reduced and corrosion of reinforcements initiates, yielding significant damage both in reinforcements and concrete. This study, aimed to investigate experimentally on evaluation performance of existing reinforced-concrete structures prone to carbonation in North Cyprus. Five inland and five coastal concrete structures of ages varying between 10 and 41 years were selected as the focus of this study. The compressive strength was determined by testing concrete core samples extracted from the selected structures. Same core samples used for determination of carbonation depth, carbonation in the samples was measured by using phenolphthalein indicator test. A contribution to the related literature on carbonation resistance performance of concrete structures under varying exposure conditions of North Cyprus was made for the very first time with the results obtained from this study. Results shows that inland structures have more carbonation depths when compared with structures located in coastal areas. The result also shows that the final carbonation depths observed in the structures are highly depended on the age, initial quality of the concrete as well as the exact local exposure conditions.